Re: Another battery question
Andy,
Thanks for your comments.?
I would suggest that RC battery packs without BMS are unsafe in the hands of people that don't understand the technology.? For example, there's nothing to prevent someone from overcharging them by using the wrong kind of charger.? Over-charging can cause thermal runaway and result in fire.? Even on the right charger, if someone doesn't appreciate the need to balance the cells, one or more cells may eventually become seriously over-charged.
I build multi-rotor RC helicopters for a living.? I don't know of any that disconnect the load when the battery drops below a certain voltage.? In my view, that would present another safety risk when the aircraft falls out of the sky.? In my early days of flying electric aircraft, there weren't suitable Li-Po batteries and chargers available, so we used Milwaukee V28 tool batteries.? However, we stripped out the BMS so that they couldn't shut off in-flight.? Ultimately, we removed the 7 individual V28 cells to assemble our own 3S and 4S battery packs.? Today, my flight controllers start the aircraft toward home at a certain low voltage threshold and land it if the voltage drops below the next threshold.? ? ? ?
Cheers,
Don
? ?
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Re: Commercial Linear amplifiers for UBITX6 and other QRP transceivers...
For those wanting good cheap amplifiers, join the ¡°AmateurRadioBuilders¡± groups.io group. ?They are just in the process of releasing two power cubes that are 1) flat in gain (+0/-0.3 dB) from 1-54 Mhz, use 12V Mosfets that are stockpiled, put out 10-20watts (you set it) with 1 mW of drive, and 2) a higher power 12v module 1-54 Mhz with similar flat gain and driven by 8 watts to 110 watts out. ?Small module you can build for under $30 and the big one for under $90. ?Yes drive the big one with the small one. ?Also being developed is a filter board/ swr-power/ pin diode switching for 100W. ?Part of the T41 project¡
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On Nov 22, 2022, at 9:35 PM, Dan Eggers N7DE <N7DE@...> wrote:
?
The kit for $209.00 looks all OK to me, but I would like to know how much soldering does it require for someone who has not been soldering for 57 years like I have been doing.? Other than that, it looks like a winner to me.
? ? ? ? ? 73, Dan, N7DE
That is probably due the name of it is Hardrock rather than Softrock
here is the link:?
--
John Faivre?WA9SGD
--
¡_. _._
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Re: sBitx #sBitx PA MOD Plan
#sBitx
I would add a bunch more pictures. ?I think that is the plan but here are some suggestions:
- Use a pointer or screw driver to identify various resistors and capacitors.
- Create very close pictures illustrating the technique of transistor removal.
- Create very close pictures illustrating the technique of resistor/capacitor removal.
- Show T/R board in detail with mounting location(s) and wiring dress.
- Show RTC similarity.
- Show enclosure disassembly/assembly in multiple pictures.
I think many can figure out how to do this without pictures but it is always better to over deliver.
My two cents worth¡?
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Re: software for cat and microphone control for ubitxv6
I have my own raspberry pi and also proxmox vm through which I passthrough the soundcard and usb cable for wsjt-x. However, I want something for SSB phone as well.
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SUNIL,
Twisted wires on the core are closer coupled and more uniform, helps to have that.
By closer coupled the coupling from from any one wire to the other two is? then
assured to be as possible to 1.? Having that be predictable is critical to circuit
design and uniformity.
The untwisted(yellow cores with added color) in the picture are not transformers
those are inductors of some specific value.
Hope that clears up what you are seeing.
Allison
------------------
Please use the forum, offline and private will go to bit bucket.
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Re: sBitx #sBitx PA MOD Plan
#sBitx
Scott,
As is I'm not a primary on this and certainly not a stake holder so any answer
I give is based on my best engineering opinion.
My call would be to not make more of this board revision and spin a new
one with all the alterations in place.? Not a cheap thing to do.? So the result
of any mods done have to be evaluated first to see if they largely solve the
big issues.? The expectation is they will.? How many can install said changes
may be limited.? Those are only development units.
Reading the document also makes clear there is material to be assembled
and shipped to the existing developers.? That's not a trivial task.
As is I've done a lot of alteration to get to some level of stability and much
of it mirrors the work being done by others.? ITs interesting and also an
experience.
Christmas, unlikely but sometimes, it can happen.? Here's to wishing.
Allison
------------------
Please use the forum, offline and private will go to bit bucket.
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Re: Another battery question
Some addendums to my suggesting the use of a Gooloo 2000 for portable power.
First off, the reviews all suggest it does well for the intended purpose of starting?
a vehicle that has a low battery.? And that it is reasonably safe.
I just measured mine, it weights about 1.4 lbs, not the 3 lbs they give
as the shipping weight with packaging and accessories.
The Amazon webpage for it says it's a "2000 Amp Car Battery Jump Starter",
Lettering on the device says "500A(3s) 400A(5s) 2000A Peak".
Amazon price at $69.99 is suddenly cheaper than Walmart, that changed since yesterday.
They claim 19800 milliamp hours.
I would read that as 19800 mAh worth of 3.7 Volt cells,
so divide by four and it is roughly 5 Amp-hours at 3.7*4=14.8 Volts.
This is typical of all the other auto jump start devices, they all have to play
the same game or they lose their mostly naive customers.
The Gooloo also says it is 73 Watt-hours, which checks since 73Wh/14.8V = 4.93 Amp-hours.
It does have a port on it with lettering that says "15V 10A", I haven't yet used it.
That port has a standard 5.5mm coaxial power connector with a 2.1mm pin.
Nice that it's a standard connector, but those are?typically rated for a max of 5 Amps.
If you want much more current than that, perhaps best off using the provided
jump cable and appropriate fusing.?
Output voltage will typically be between 15 and 12 VDC depending on charge state.
Not bad.
73 Watt-hours means you could run a rig drawing 10 Watts continuously
for 7.3 hours.? ?Adequate for most ham QRP outings.
Or a rig drawing 400*12=4800 Watts for 5 seconds, at which point the battery would overheat and shut down.
Or maybe start your car some dark night.
That 10 Ah Lumenier that Don pointed to has almost exactly twice the claimed capacity,
? ? 10 Ah at 14.8 Volts would be 148 Watt-hours.
The Lumenier is also double the price, and that does not include a proper charger with BMS for it.
However, the Lumenier should run a 3700 Watt rig for 2.4 minutes, which could actually be useful.
And might start a small car in a pinch, though be careful as it probably doesn't have overcurrent protection.
Jerry, KE7ER
On Wed, Nov 23, 2022 at 06:08 PM, Jerry Gaffke wrote:
Speaking of fast discharging, it is amazing how well the new breed of auto jump start
batteries work.? I have a Gooloo 2000 which I rather like.? In addition to being able to
jump start an F250 diesel, it has a 15V 10Amp port out the side to run a small transceiver.
It charges slowly through a USB-C port.? Fast discharge is not possible unless you
plug the jump start cable into the side of the pack.? Includes a flashlight and several
USB power out ports.? ?Weighs 3 lbs.? Walmart sells it for $78.? Might save your bacon
if you leave the headlights on while?working Parks-On-The-Air.? Using the battery off a
shop tool also makes good sense to me.? Why buy an extra battery for ham gear
when you can make use of a battery that is used for other purposes?? A high volume
consumer product is often cheaper than a niche product.
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Re: Another battery question
Don,
That Lumenier is a 10 Amp-hour battery, nominally 14.8 Volts.?
Rated for 25C, which means a maximum current of (10 Amp-hour) * 25C = 250 Amps,
where the 25C has the rather odd units of Amps per Amp-Hour.
So it can fully discharge that battery in (60 minutes)/25 = 2.4 minutes,
with a power of? ? 250 Amps * 14.8 Volts = 3700 Watts.
A 3700 Watt appliance would blow fuses at 120 VAC, you would need a 240 VAC outlet.
If you insist on moving that much power in and out of such a package weighing 0.845 kilo,
that is inherently dangerous.? But that's what the RC aircraft guys feel they need.?
When an aircraft is taking off it needs a burst of power, much more than when cruising along
in even flight.? The battery has to be as light as possible.? And when they land with a
depleted battery, they want?to recharge it as quickly as possible (in this case around 2.4 minutes,
assuming the max charge rate is the same as the discharge rate of 25C)
That way they can get it back up in the air again for more fun.? So they really are wanting to
move 3700 Watts in and out of that battery.? That's inherently unsafe, and why vendors also
sell a "Lipo Safe Bag" to hold the somewhat expected explosion when charging at 3700 Watts.
However, if you take that same product and charge/discharge at 10 Amps,?and have an
appropriate BMS hooked up when charging, there is very little danger of an explosion.
Just make sure you don't short out those two roughly 1 cm diameter copper cables.
Same applies to the starting battery in your car, not far from all that gasoline.
Jerry, KE7ER
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On Fri, Nov 25, 2022 at 07:11 AM, Don LeRoi wrote:
The common brick lithium battery packs are the least safe because they are very vulnerable to abuse.? That is:? over-charging, over-discharging, shorting, puncturing, and failure to balance the cells.? These are the battery packs that have a main power lead and a balancing connector:
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Re: Another battery question
Very cool, Jerry!? It sounds lime you've a good handle on things there!? I agree that commercial and most DIY BMS have wimpy shunts. I expect you already know that you likely don't need to shunt often, especially with your very conservative voltage settings.? (For yet another tangent, the Smart ev and my current Outlander PHEV both have similar 250 mA-ish shunts. It takes a couple of cycles, or a day plugged in, but the battery will eventually balance. I seldom care, tho, as that extra 1/10 of a mile range isn't usually an issue hihi). You're right that there's no point to charging cells to 100% - especially the ones like LFP that carry most of their energy at a lower voltage. It'll definitely reduce the cycle life. (From Thundersky-Winston, for example - operational voltage is 3.8, though charge/discharge tests run to 4.0 V.? I used to set shunts to 3.65 and charge to 3.6. Shunts didn't activate until a cell got weak. Ok, the wind is back - time to sail. 73 all
? Andy
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Re: Another battery question
Andy,
Sounds like you have made a career in offgrid power, something I have only dabbled with.? The earthship must have been a major project and a big learning experience, I was looking hard at that before going with strawbale infill on our post-and-beam house, has a Faswall basement and is positioned for passive solar.? Had 2.2 kW of PV till a couple years ago, now at 4.4 kW and will probably double that soon so we can get through dark NE Oregon December weeks without running a generator.? Most winter heat is currently from windfall ponderosa pine, as I get older and less inclined to swing a chainsaw we may pivot to a large well insulated hot water reservoir in the basement heated by excess PV on occasional sunny winter days to keep the hydronic floors warm in bad weather.? Wind and micro-hydro are vague possibilities here, but enough PV for cloudy weather at $0.50 per Watt is hard to beat.
When we first bought, got by with a 20 foot yurt and 45W worth of PV from Harbor Freight and a couple used golf cart batteries.? Most of that power went to a Sundanzer DCR225 fridge, cooling it off during the day and coasting through the night.? Have power lines to the property, but was quoted $15k to get power to our building site if I dug the ditch.? Was happy to hear that, as I was inclined to go offgrid anyway (we all need hobbies!).? With 4.4 kW of PV and 29 kWh of LiFePO4, we pretty much never use the generator and my partner Liz need not think about my hobby when using the 26 cuft front loading fridge/freezer, 3 chest freezers, and dishwasher with superheater.? I've given up complaining when and empty rooms are left with the very efficient LED lights left on.? Being remote, power to the area occasionally goes out, and I rather enjoy telling the neighbors "no" when they ask if our power went out too.?
The JBD 200A BMS has a rather wimpy passive balancing scheme, discharging any cells with excessive voltage at maybe 250mA.? This is proving adequate for the 2P16S pack of relatively well behaved LF280K cells from Docan, though I found it necessary to disable balancing at anything under about 3.41 Volts as the charge curve for the various cells differed enough below that value that the wrong cells were getting discharged.? I'd guess this is because any cells with tighter specs were cherry picked for use in EV's.
A minor nit of which I am sure you are aware, but seems worth pointing out to the forum:
>? "While the operational voltage per cell can vary between about 2.4 and 3.8, the family still has a max of 4.2 and a minimum of about 2V per cell."
The LiFePO4 cells should never be charged much above 3.6 Volts, they would definitely be damaged if held at at 4.2 Volts.? Pretty much all the other Lithium Ion chemisties are good to around 4.1 or 4.2 Volts as stated.?
I charge my battery to a max of 54.8 Volts (3.425 Volts per cell) and shut things down when it falls below 48.0 Volts (3.0 Volts per cell).? This is using my Magnum PT100 charger, which was designed for lead acid and so is not aware of individual cell voltages.? That range gives me something close to 99% of the available capacity and allows fast charging when only occasional sun is available, but avoids extreme highs and lows where top balancing (at the high end) and matched capacities (at the low end) become critical.? As these cells diverge with age, I may need to program those high and low voltages to something more conservative.? Ideally, I would instead figure out how to tell the PT100 to stop charging (without the possible voltage transients of letting the BMS take care of this) when any single cell exceeds 3.6 Volts.? Letting the BMS relay cut out the battery when any single cell falls below 2.5 Volts is probably just fine.
Looking forward to having an electric vehicle, especially if it can be cabled up to the house during a week of foul weather to make good use of that 70 kWh battery.? ?Will check out Endless Sphere.? When a difficult technical issue is raised on diysolar there can be ten different answers, and I might find eight of them to be misinformed.
Jerry, KE7ER
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On Thu, Nov 24, 2022 at 01:06 PM, AndyH wrote:
I appreciate your comments about your off grid battery.? While my battery business was tailored to ebikes, electric motorcycles, and the occasional plug-in Prius conversion, my personal goal was off-grid.? I'm a huge fan of the passive solar Earthship and have a complete solar and wind package (minus battery) for a future building.? While the energy demands for a passive solar building are about an order of magnitude lower than a conventional US single family house, my needs now that I'm living aboard a sailboat are down another order of magnitude.? My PV needs dropped from 3KW for the Earthship to 100W.? My current house battery is the battery I made for portable radio use - 2P4S 25 Ah LFP cells, a 100 A JBD BMS, and a 10A Genasun MPPT charge controller, all in a plastic 50 Cal ammo can.? I would have preferred to use a Stewart Pittaway DIYBMS, but didn't get it integrated in time before I put my lab into storage before the move. If one is a DIY type, it's really hard to beat the DIYBMS, especially if they use Victron balance of systems equipment.
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Re: Another battery question
Don, ? ?RC batteries aren't unsafe because they don't have an i ternal BMS. In RC use, management is split between the charger on the ground (charges, controls voltage and current, and balances). In the air, the speed controller monitors battery voltage and disconnects the load. The only weakness is cell level low voltage isn't monitored (though the low voltage disconnect is conservative for that reason). (An example, not a recommendation)
My bench battery for the past 12 or so years was a 'naked' 4S 10 Ah LiFePO4 pack made from PSI cells. I didn't worry about low voltage monitoring because I seldom discharged to 50%. I connected to an analogue BMS when charging with my bench PSU.? I use LiCo pouches the same way.? Without automation, we become the management system - the battery is as dangerous as we are.
If their bulk works for the mission, tool packs do make things easy, tho - and using them definitely reduces the need to not touch batteries until after coffee!
Best, Andy
On Fri, Nov 25, 2022 at 09:11 AM, Don LeRoi wrote:
The common brick lithium battery packs are the least safe because they are very vulnerable to abuse.? That is:? over-charging, over-discharging, shorting, puncturing, and failure to balance the cells.
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Re: Another battery question
What needs to be respected is written on the label...
Lithium tech allow a significantly greater amount of energy
to be in a far smaller and lighter package.? And if not managed
they can deliver it all in short order, such as short circuits.
25C and 50C? that means the nominal discharge current times
either as a maximum.? ?So we are talking in excess of 50A and
as high as 500A,? things melt if not adequately fused or
otherwise protected.? That can include the battery itself.
That means for a lot of uses its safe if not abused, that includes
both mechanical and electrical abuses. Specifically do not bend,
fold, spindle, mutilate, peirce, overheat, charge while too hot or
too cold.? All kidding aside how many of those abuses are
perpetrated by the average Ebiike or Hoverboard user?
That's a 148WH battery, if pushed to the limit easily delivers?
7400wh for maybe a minute.? That is a lot of energy.? For that
level of power we are talking the equivilent of a 10Hp engine!!
Its also enough power to run a 100W radio (about 240W
DC input) for maybe hours depending on TX and RX time.
While being able to supply the needed 18-20A on 100W TX.
This is why power tools and other safe batteries are max
current protected for discharge.? Most all have a matching
charge system.??For example I have a built up 18650
11AH 3S4P pack with BMB selected for a current cutoff
of 8A.? Since its only running a FT817 that is more
than needed but enough to protect the battery from a short.
If I were to attempt to charge with more than 13.1V the
board cuts off the battery and rendered it safe.? If any cell
in the pack goes under 2V or over 4.2 it also cuts off. It uses
a specific charger I made for it.?? That is basic protection.
Another pack with BMS does both that and has a charging
port that has the needed current and voltage control for
charging with uncontrolled voltage source, again for safety.
It also does charge leveling plus all the BMB safety functions.
But the BMS value is it allows for a simple wall wart charger
with enough output voltage as all the management is on
the board.
So if I were to use that pouch pack battery it would be placed
in a heavy wall plastic case with BMS added and suitable
connectors for field and other uses.??
Or I'd just buy a battery with all that is in a nice hard plastic
case with standard tab or wire connectors.
FYI most of the 7-9ah Lithium tech (usually Lipo or Lifepo4 families)
replacement for gell cell 12V batteries do all that as well.
However if you buy a quality battery with protection it will outlast most
other alkaline (NiCd, Nimh) and lead acid tech but a wide margin
making their cost actually economical.
Allison
------------------
Please use the forum, offline and private will go to bit bucket.
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Re: Another battery question
The common brick lithium battery packs are the least safe because they are very vulnerable to abuse.? That is:? over-charging, over-discharging, shorting, puncturing, and failure to balance the cells.? These are the battery packs that have a main power lead and a balancing connector:  They have no built-in protection. Cordless power tool lithium battery packs are among the safest because they are encased in hard plastic and have built-in short circuit, over charging, and over discharging protection.? Also, you can't forget to balance the cells because balancing is also internal. Cheers, Don
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Hi Thomas,
Any news on Sbitx stock availability?
Thanks,
Amol
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Re: Another battery question
Also, note that when clicking on "Battery" in the upper left of
you are presented with the following choice:
? ?Category? ??Battery
? ? ? Li-ion battery
? ? ? LiFePo4 Battery
? ? ? Ni-MH Battery
? ? ? Ni-cd battery
They wouldn't sell as many if they made it too complicated.? ;-)
Jerry, KE7ER
On Thu, Nov 24, 2022 at 05:00 PM, Jerry Gaffke wrote:
Curious, we wound up at the same vendor.
From? ?
"About Us? ??Docan?Technology (Shenzhen) Co., Limited is a famous OEM battery factory with providing battery solution for customers, located in Shenzhen, Guangdong Province of China."
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Re: Another battery question
Curious, we wound up at the same vendor. From? ?
"About Us? ??Docan?Technology (Shenzhen) Co., Limited is a famous OEM battery factory with providing battery solution for customers, located in Shenzhen, Guangdong Province of China."
Bought my first 16 LF280K cells from the warehouse in Houston, arrived via UPS within a week. Was no longer in a hurry when getting the second set of 16, so had those shipped from China,? those took about a month before being dropped off by UPS and the price was significantly less. All cells were pristine, extremely well packaged, and worked well. Both buys were made through the same Docan rep, and payment for both was made through alibaba, paypal, and my credit card company. A bit scary to buy that way, but I read enough favorable reviews of Docan to buy with confidence. Jerry, KE7ER ?
On Thu, Nov 24, 2022 at 01:06 PM, AndyH wrote:
I've not used powerwholesale.? ....? ? ?I have had good results from Docan Power and their Houston, TX warehouse.
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Re: Another battery question
Andy, I looked at your bio on QRZ.COM... Very impressive and thought inspiring and it encourages imagination. Thanks.
Bob KK5R
On Thursday, November 24, 2022 at 04:06:46 PM EST, AndyH <awhecker@...> wrote:
Lost a reply on the phone...let's try this again on the laptop...
With respect, Jerry, "common usage" depends on the group being surveyed.? For the general public, I agree that "lithium ion", "Lithium polymer", and LiCoO are used interchangeably.? It's like saying all capacitors are electrolytic.? In the marine world, lithium ion specifically means LFP/LiFePO4.? In research and transportation, lithium Ion means the family and one has to identify the chemistry being discussed.? Even within specific chemistries, there can be 'power cells' or 'energy cells', and some LFP are doped with yttrium or other elements. While the operational voltage per cell can vary between about 2.4 and 3.8, the family still has a max of 4.2 and a minimum of about 2V per cell.
I've not used powerwholesale.? I used to import 10 Ah cylindrical cells from PSI in Taiwan.? I've used A123 cylindricals; Headway, PSI, Thundersky (thundersag...), CALB, and other prismatic LFPs. I've also used plenty of LCO pouches from Hobby King, both for RC and portable radios.? NiCd and NiMH before that.? My 5KW electric scooter/motorcycle was my primary vehicle and BMS test bed when I was building batteries.? It had a 21S pack of 60 Ah Thundersky LiFeYPO4 cells.? I have had good results from Docan Power and their Houston, TX warehouse.? They stock grade A and B cells from CALB, CATL (supplies VW), and EVE. DIYSolar and DIYElectricCar both have too much bad info. I prefer the signal to noise ratio of the Endless Sphere forum - more engineers and fewer "youtube influencers".
I appreciate your comments about your off grid battery.? While my battery business was tailored to ebikes, electric motorcycles, and the occasional plug-in Prius conversion, my personal goal was off-grid.? I'm a huge fan of the passive solar Earthship and have a complete solar and wind package (minus battery) for a future building.? While the energy demands for a passive solar building are about an order of magnitude lower than a conventional US single family house, my needs now that I'm living aboard a sailboat are down another order of magnitude.? My PV needs dropped from 3KW for the Earthship to 100W.? My current house battery is the battery I made for portable radio use - 2P4S 25 Ah LFP cells, a 100 A JBD BMS, and a 10A Genasun MPPT charge controller, all in a plastic 50 Cal ammo can.? I would have preferred to use a Stewart Pittaway DIYBMS, but didn't get it integrated in time before I put my lab into storage before the move. If one is a DIY type, it's really hard to beat the DIYBMS, especially if they use Victron balance of systems equipment.
Best, Andy
KG5RKP/MM
On Thu, Nov 24, 2022 at 09:05 AM, Jerry Gaffke wrote:
Andy,?
No real argument, I agree with most of what you say.
'Common usage' is a useful thing to be aware of, as this is how most other people describe
what they are doing, and even how manufacturers describe what they are selling.
In the world of lithium ion batteries, LiFePO4 chemistry is different enough that it is
necessary to call that out.? In particular, voltage per cell is different.? Everything else
often gets lumped together under the more generic term of lithium ion.
Some 15 years ago I bought a few raw pouch cells because they were cheap.
Big mistake.? If building a small battery pack, go with cylindrical cells like 18650's.
The pouch cells rupture easily and need far more physical protection.
You definitely want appropriate electrical protection circuitry.? If figuring all that out
does not sound fun, then buy a successful battery pack of some sort and use
the charging device that comes with it.? Could be borrowed from a shop tool,
an auto jump start device with a well protected low current port, or one of the
excellent Bioenno LiFePO4 batteries.
If building a big battery pack and you are interested in an educational project,
I can recommend the prisimatic LiFePO4 bricks from?? ?
Shipped from China, so may be tough to get if they go into lockdown again.
These have likely been passed over by electric vehicle manufacturers for
having specs somewhat out-of-family, but are relatively cheap.
Lots of even cheaper vendors on alibaba, but be careful as many are selling
used or damaged cells.? ?Good info on?https://diysolarforum.com
Being offgrid, there's a bank of 32 EVE LF280K cells in the basement powering
this conversation, configured as 2P16S, 29 kWh total, along with a JBD 200A BMS.
Jerry, KE7ER
On Thu, Nov 24, 2022 at 03:32 AM, AndyH wrote:
Yes, cobalt levels in some LiCoO variants are decreasing. The relative safety standings remain, however.?
? 'Common usage' isn't a useful metric. Folks interested in selecting a product within a family benefit from understanding when a disk ceramic doesn't replace an electrolytic, or why NP0 matters, right? Have you heard that nobody makes their own radios these days? hihi
? Metal cased cells are 'safer' only if one is working with individual cells and not a properly constructed battery. Anodes and cathodes need to be held together during charging and discharging. It's part of that 'safe if not abused or mishandled' thing.
? Look at how Tesla makes their reduced cobalt LiCoO batteries. Even though they start with metal cased cylindrical cells, they still have to encase them in fire retardant adhesives. In a crash they can still burn furiously and the fire can be difficult to extinguish.? (Sandy Munroe also shows how pouch cells are packaged into a proper battery.)
? Battery management chips are cheap these days, and one can purchase small battery management modules that provide cell balancing, charge and discharge current control, and cell-level high- and low-voltage protection while reporting battery health via low-power Bluetooth. Fun times to DIY batteries.
? 73, Andy
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Re: software for cat and microphone control for ubitxv6
Hi,
Here are some resources for remote rig control.
The best package I've seen seems to be this.
Supposedly the source code is on Github, but I only found an empty repository for RigPi when I just now checked.?
Rather than the MFJ hardware and a Raspberry Pi, I have one of these little servers that I plan to use instead of a Pi, and I'll try to use a USB sound dongle. (If I can find the source code.)
Here is a very interesting video on a Arduino package that makes using the ESP32 (and some others) for audio application easy.
Tom, wb6b
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Re: Another battery question
Lost a reply on the phone...let's try this again on the laptop...
With respect, Jerry, "common usage" depends on the group being surveyed.? For the general public, I agree that "lithium ion", "Lithium polymer", and LiCoO are used interchangeably.? It's like saying all capacitors are electrolytic.? In the marine world, lithium ion specifically means LFP/LiFePO4.? In research and transportation, lithium Ion means the family and one has to identify the chemistry being discussed.? Even within specific chemistries, there can be 'power cells' or 'energy cells', and some LFP are doped with yttrium or other elements. While the operational voltage per cell can vary between about 2.4 and 3.8, the family still has a max of 4.2 and a minimum of about 2V per cell.
I've not used powerwholesale.? I used to import 10 Ah cylindrical cells from PSI in Taiwan.? I've used A123 cylindricals; Headway, PSI, Thundersky (thundersag...), CALB, and other prismatic LFPs. I've also used plenty of LCO pouches from Hobby King, both for RC and portable radios.? NiCd and NiMH before that.? My 5KW electric scooter/motorcycle was my primary vehicle and BMS test bed when I was building batteries.? It had a 21S pack of 60 Ah Thundersky LiFeYPO4 cells.? I have had good results from Docan Power and their Houston, TX warehouse.? They stock grade A and B cells from CALB, CATL (supplies VW), and EVE. DIYSolar and DIYElectricCar both have too much bad info. I prefer the signal to noise ratio of the Endless Sphere forum - more engineers and fewer "youtube influencers".
I appreciate your comments about your off grid battery.? While my battery business was tailored to ebikes, electric motorcycles, and the occasional plug-in Prius conversion, my personal goal was off-grid.? I'm a huge fan of the passive solar Earthship and have a complete solar and wind package (minus battery) for a future building.? While the energy demands for a passive solar building are about an order of magnitude lower than a conventional US single family house, my needs now that I'm living aboard a sailboat are down another order of magnitude.? My PV needs dropped from 3KW for the Earthship to 100W.? My current house battery is the battery I made for portable radio use - 2P4S 25 Ah LFP cells, a 100 A JBD BMS, and a 10A Genasun MPPT charge controller, all in a plastic 50 Cal ammo can.? I would have preferred to use a Stewart Pittaway DIYBMS, but didn't get it integrated in time before I put my lab into storage before the move. If one is a DIY type, it's really hard to beat the DIYBMS, especially if they use Victron balance of systems equipment.
Best, Andy
KG5RKP/MM
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On Thu, Nov 24, 2022 at 09:05 AM, Jerry Gaffke wrote:
Andy,?
No real argument, I agree with most of what you say.
'Common usage' is a useful thing to be aware of, as this is how most other people describe
what they are doing, and even how manufacturers describe what they are selling.
In the world of lithium ion batteries, LiFePO4 chemistry is different enough that it is
necessary to call that out.? In particular, voltage per cell is different.? Everything else
often gets lumped together under the more generic term of lithium ion.
Some 15 years ago I bought a few raw pouch cells because they were cheap.
Big mistake.? If building a small battery pack, go with cylindrical cells like 18650's.
The pouch cells rupture easily and need far more physical protection.
You definitely want appropriate electrical protection circuitry.? If figuring all that out
does not sound fun, then buy a successful battery pack of some sort and use
the charging device that comes with it.? Could be borrowed from a shop tool,
an auto jump start device with a well protected low current port, or one of the
excellent Bioenno LiFePO4 batteries.
If building a big battery pack and you are interested in an educational project,
I can recommend the prisimatic LiFePO4 bricks from?? ?
Shipped from China, so may be tough to get if they go into lockdown again.
These have likely been passed over by electric vehicle manufacturers for
having specs somewhat out-of-family, but are relatively cheap.
Lots of even cheaper vendors on alibaba, but be careful as many are selling
used or damaged cells.? ?Good info on?https://diysolarforum.com
Being offgrid, there's a bank of 32 EVE LF280K cells in the basement powering
this conversation, configured as 2P16S, 29 kWh total, along with a JBD 200A BMS.
Jerry, KE7ER
On Thu, Nov 24, 2022 at 03:32 AM, AndyH wrote:
Yes, cobalt levels in some LiCoO variants are decreasing. The relative safety standings remain, however.?
? 'Common usage' isn't a useful metric. Folks interested in selecting a product within a family benefit from understanding when a disk ceramic doesn't replace an electrolytic, or why NP0 matters, right? Have you heard that nobody makes their own radios these days? hihi
? Metal cased cells are 'safer' only if one is working with individual cells and not a properly constructed battery. Anodes and cathodes need to be held together during charging and discharging. It's part of that 'safe if not abused or mishandled' thing.
? Look at how Tesla makes their reduced cobalt LiCoO batteries. Even though they start with metal cased cylindrical cells, they still have to encase them in fire retardant adhesives. In a crash they can still burn furiously and the fire can be difficult to extinguish.? (Sandy Munroe also shows how pouch cells are packaged into a proper battery.)
? Battery management chips are cheap these days, and one can purchase small battery management modules that provide cell balancing, charge and discharge current control, and cell-level high- and low-voltage protection while reporting battery health via low-power Bluetooth. Fun times to DIY batteries.
? 73, Andy
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Re: Another battery question
The 2P16S bank of EVE LF280K LiFePO4 prisimatic cells here replaced a
6 year old bank of eight Trojan L16RE-B 370AH 6v flooded lead acid batteries.
Those L16RE-B's were quite good for lead acid, the chart in the datasheet
at? ?
shows them to be good for 4000 cycles to 20% discharge, and 1000 cycles to
80% discharge.? So really doesn't matter how deep you discharge an L16RE-B,
you get the same amount of energy storage over the life of the battery.?
I worked the L16RE-B's hard during dark winter weeks, got more life out of them
than I had reason to expect.
?
One reason to avoid deep discharge of lead acid batteries is that without a BMS
(battery management system) monitoring each cell, eventually a weaker cell will
develop that discharges completely (or even goes negative)?before the voltage of
the entire bank falls 15% down from nominal.? The over-discharge will damage
that weak cell even further, and then the entire bank fails.? So conventional wisdom
is to only discharge lead acid down to about 50%.? When charging, flooded lead
acid will self balance nicely since any cells that reach the full charge state first
will consume the extra power by breaking down water in the electrolyte.
Be sure to check occasionally if water must be added.
An automotive lead acid starter battery is designed only for high starting currents.
You might get a dozen deep discharge cycles from such a battery before it fails.
The primary thing to look out for when transitioning from lead acid to lithium
is that lithium needs some other strategy to balance the charge state of
all the cells.? Once a cell reaches a fully charged state, any additional power
will damage it.? For this reason we need a BMS that detects when any cell
exceeds it's maximum rated voltage (or minimum voltage on discharge) and
disconnects the battery from the rest of the system to prevent battery damage.
The BMS on a lithium battery also has a mechanism to weakly discharge any
cells that are reaching maximum voltage before any other cells when charging.
The lithium cells then "top balance", and should reach full charge simultaneously.
One issue to consider when transitioning from lead acid to lithium is what happens
if the BMS detects an overcharged cell and disconnects from the charging device.
This never happens with lead acid cells, they tolerate overcharging rather well.
A lithium battery disconnect when being charged may cause momentary voltage transients
depending on the design of the charging device, high enough to damage any
electronics involved.? In my case, I monitor my BMS closely to ensure it is keeping
the cells reasonably balanced, and have the charger programmed to stop charging
at a reasonably low system voltage.? A BMS shutdown due to high cell voltage?
will hopefully never occur, and with luck the transients would not be excessive.
The L16RE-B's were good, but my new LiFePO4 cells are cheaper per kWh
and should give roughly 5 times the number of full discharge cycles.
They will last for a couple decades, at which time I expect household fusion
reactors to be cheaply available.? ;-)
Jerry, KE7ER
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Don LeRoi
MadRadioModder
Bob Lunsford