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Re: Complex design issues
Thanks Dan. I don't have the figures with me right now and you may be right about the 30 amps @ 4 knots as well as the practicality of hull speed. The Fischer-Pandas ARE Direct Current / 48 volt, 10kw gen sets. Generally, all I need is one gen to give up to a max of about 200 amps@48 volts. The ElectricYacht? 2.0 system is two motors in tandem. Like the two gen sets, It's redundant power and energy and cruising on one generator is easy but if you're in a storm, heavy sea or serious currant, #2 gen with #1coming on will kick in the second motor, and hopefully, get you outta there. The problem, is I don't want to be a total slave to the generators. I'd like to be as efficient as possible, by charging the bat.bank(s) with enough volts and enough amps to travel 4 or 5 hours on batteries alone. Getting that configuration as efficient as possible is what I need help with. I can't put on any more than the 8 100watt PVs (it's what I have) and the one 200 watt for maintaining the house batteries. I haven't installed the inverter yet and charging by shore power is still to be worked out. Anyway, thank you for your input! Dale On Fri, Nov 29, 2024, 12:23 PM john via <oak_box=[email protected]> wrote:
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Re: When the ideal house voltage please stand up?
If I am reading you right, apologies if I am getting your point wrong, you are proposing using 120v DC from the batteries to run standard AC appliances as well as the drive motor. This can’t be done, DC and AC systems must be separate. Also, 120vdc system voltage is doable, but much less standard than 48v which is a common voltage in larger solar systems. ??
Further, it is generally accepted that 48v is the highest relatively safe voltage, above that you have to be much more rigorous about your wiring and moisture protection. The difficulties of higher voltages are not insurmountable but if you want a system that is safe and insurable, you’d be better off going with 48v as it is safer and ?more standard than 120v.? 120vdc as from a battery will not run most standard AC appliances, ?you’d have to use an inverter to make AC from the DC and that would run the AC house loads. The wiring for AC and DC follows different standards, for a 120vdc system every plug and connection would have to be esoteric and coded to disallow connection to any normal appliance. This negates any convenience gained by having the AC system and DC system the same voltage. Generators (normal ones at least) only make AC which would have to be converted and controlled to charge batteries or run a motor.?
AC motors can be speed controlled, but the electricity ?needs to be converted from AC to DC and back again, losing efficiency and adding complication.? 24kw is a lot, that’s 480 amps at 50v, you’d need big wires, but you could go with 72v, which is a common system voltage in dc drives if you really need that much power. That would take the amps down to 330, which is still big but not too bad.? Consult with the thunderstruck people, they’ll get you sorted out.? That would be a great boat to go electric with, you’ll have plenty of room for batteries and solar! anton |
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Re: Complex design issues
Ok, ball park...? How much is one of these things?? ? 200 pounds doesn't sound bad for a diesel gen.
On Friday, November 29, 2024 at 10:52:46 AM CST, Dan Pfeiffer <dan@...> wrote:
Is this a Buccaneer 32? On 2024-11-29 11:12 am, Dale Shomette via groups.io wrote:
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Re: Complex design issues
开云体育Is this a Buccaneer 32? On 2024-11-29 11:12 am, Dale Shomette via groups.io wrote:
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Complex design issues
I have a 32' Bayliner sailboat (now dismasted) that I've gutted and am turning it into an electric hybrid. It has an 8 battery (185 a/h 12 volt each) battery bank of AGM Oddysey batteries to power a (to be purchased) ElectricYacht 2.0, 48 volt motor drive system. I have 8 solar panels, 100watts each to augment the two Fischer Panda 48 volt 10kw diesel gen. sets. I've taken the 13' mainmast spar and am stepping it where the main master was, with a 500watt wind generator mounted on top. To flesh it out a bit more, I've installed a separate 4 battery bank forward as the house batteries, with a 200watt PV on the forward cabin top to keep them topped up. ? Having said all that, I'd like to configure the 800 watt set of PVs to meet the 48 (actually need 54-6) volt requirement to charge the 8 battery bank but also maximize amperage. 10-11amps/hrs isn't much to plug into a 370amp bank. The ElectricYacht will need roughly 60 amp/hr for a 3.5-4knot speed, up to 270 amps/hrs to reach a 7- 7.5 knot hll speed. The gen sets can run the motors by themselves and/or charge the batteries but I would like to get as much quiet time propulsion as possible. The gen. sets only put out 60 decibels of noise but would like to keep their use to a minimum. How would you do the overall PV / wind turbine configuration, and voltage and amperage to the battery bank? Should I utilize one 4? 185amp 48 volt bank at a time or use and charge both at the same time? Other insight would be appreciated. Thanks so much. Dale |
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Re: When the ideal house voltage please stand up?
Not sure what you are exactly thinking of, but if you are saying why not use a 120V AC motor for propulsion? The reason would be efficiency. If you are converting from DC (Batteries) through an Inverter(90% Efficiency) to an AC Motor(75-90% Efficiency), that is not as efficient as Batteries directly to a Brushless DC Motor(92% Efficiency). Also, on boats, you should not use residential wiring or connectors... you have to use marine grade everything. Typically on a sailboat, you would have a big propulsion battery bank, and have a DC to DC converter, to go from your say 74 Volt propulsion battery bank to 12 volt house power. And most likely have a small 12 volt battery bank that is charged by the DC to DC converter and Solar. Then you would have an inverter for any 110 volt house loads, like a microwave, tv, computer... ? On Thu, Nov 28, 2024 at 4:37?PM Newt via <mrkgillis=[email protected]> wrote:
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When the ideal house voltage please stand up?
Hi all,? I monitor this group a lot but rarely contribute. That's going to change. While powering over a current over a bar here in Oregon, my v drive ended with a loud bang followed by a grinding noise and no power to the prop. Well I will use this opportunity to go electric. In talking to the thunderstruck guys, they suggest 18 or even 24 kw (40 ft Valiant) . I thought why not just use their reduction drive and go with 120 for the house and the? aux? Advantages... More power to aux Standardized wiring (cheaper) Home appliances (cheap) Solar to 120, gen to 120 easy to do.? Dis Marine stuff is mostly 12 volt. So will need step down for instruments, radar etc What do you think...anybody done this? Why not? |
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Lake Ontario folks?
开云体育I was wondering if there are folks here who are located in Lake Ontario and would be willing to help me assess the system that is on my boat that the previous owner put together. I obviously need to get up to speed on this but as this board demonstrates often, there are many considerations and it would be nice to have a sense from someone else who has diagnostic tools and the like. My boat is located now in Sakets Harbor. ? ? ? |
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question about lightning
开云体育Hi Folks, This past season was the first one for me using my Pearson 10M but was a somewhat shorter one due to some health issues of my family members. I did get out several times and was able to begin using the system that the previous owner had put together which is a Thunderstruck with 4 Li Cells for 48V and 196Ah, I believe. My question is what measures any of you take during thunderstorms if you cannot be back to the marina or get off the boat. My boat has a mast that is keel stepped on a metal plate that is bolted into the metal portion of the keel. It would seem this is an adequate path for a lightning strike if it were to occur and that a reasonable approach if we have to be on the boat through a storm is to get into the forepeak and away from the mast and Li cells which are in the port quarter berth. Is there anything else that could be done aside from switching off the motor, path to cells, etc. Presumable the breakers/fuses on the mast electronics will blow to hopefully protect some of that. ? Thanks, Scott ? |
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Re: Sevcon gen 4 overload?
Hello Tim,
Are you able to count the flash on the SEVCON ? You must have between 1 and 15 flashes (see in the attached file).
It is preferable to connect to the controller via the CAN bus and IXXAT's USB-to-CAN interface and DVTC software...
This is a very interesting case: propeller jamming. The drive will send the programmed maximum torque and wait for the motor to turn. The motor and the drive may heat up, so we should have a thermal cut-out, or a control law that says “STOP, the motor hasn't been running for too long...”. |
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Sevcon gen 4 overload?
Recently I had a fail with my electric motor installation on my yacht which I couldn't immediately diagnose. Subsequently I had a diver cleaning the anti-foul and he found masses of fishing line wrapped around the propellor. It was apparently quite tight and while he managed to remove 90% of it and got the propellor to rotate, I still can't get the controller to respond. I have looked at the fault finding led on the controller casing and when the key is turned on I am getting multiple flashes far in excess of anything in the manual and then fades out. Given that I seem to have full charge, fuses intact and nothing appears during visual inspection I am at a bit of a loss on how to proceed. I am tipping that it must have got overloaded with fishing line jamb and that some sort of overload has been tripped...
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Any have any thoughts? |
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Re: Cells (modules) are dying.
开云体育The 10yr lifespan might be a bit skeptical---I’m still driving my 2011 THINK City car (85kmiles) on its 1st battery pack with date codes of 2010 --- ie. 14 years+ old cells.? I’ve never had an issue with any of the cells, BMS or modules in the 12 years I’ve driven the car (knock on wood).? But then I have been pretty lucky.? The furthest I’ve driven on a charge was about 81 miles maybe 11 years ago.? Then the other day I drove 66 miles and still had about 7 miles range left before the car would shut me down… I have also been powering my 26’ boat with 10 of the same module assemblies for about 10 years now with no issues or degradation that I’ve seen.? Early on, with the 1st module to power my boat I came out to the marina after being away for a month and found the module had dropped from near 48v to 3vDC.? My heart sank (I had paid about $1000 for it at the time).? I had forgotten to physically disconnect it from the powered-off charger, which drained the module over time.? Not panicking, I pulled it out, took it home and found it was already back at 13v.? Slowly I charged it up to the 30v minimum and then charged at a good charge rate to 48v. ?It absorbed rated capacity and all cells tracked.? I was pretty lucky. A Nasa study on lithium chemistries found that contrary to popular opinion, the cells don’t just die when you take them below, say 2.5vpc (e.g. lithium ion). ?Rather, they found no irreversible damage until the cell voltage dropped below something like minus 0.4v (guessing).? Essentially this meant that any single cell that under load can only drop to zero volts won’t get permanently damaged.? The problem comes when we string these little buggers in series.? In that typical case, even a single module of, say, 12 cells in series runs a significant risk that at least 1 of those cells will reverse voltage if a load is connected up that drains the module (or pack).? Less risk if the cells are all balanced and have nearly identical capacity. There are ways to eliminate the risk, but all add parts, volume, connections and cost. ? -MT ? From: [email protected] [mailto:[email protected]] On Behalf Of gsxbearman via groups.io ? I think that the charging to 100% is only detrimental to NMC batteries, not LFP. But you are correct that all the batteries have about a 10 year lifespan (max for NMC, min for LFP). The thing to remember about the cycles is that the cycle rating is for degradation down to 80% of original capacity. This is still a very usable battery if this happens before your 10 years ends. Most of the NMC batteries are rated around 2000 to 3000 cycles and LFP around 4000 to 8000 cycles. The 80% to 20% use/charging is to prolong the cycle life of NMC batteries because the NMC’s get most of the charging/discharging degradation in this first and last 20%. The cycle rating is so large on LFP’s that there is no need to prolong the cycle life because they will age out before they reach 4000 cycles. And they don’t seem to suffer near as bad degradation in these First and last 20% ranges. From everything I have read the main detriment to life expectancy is rate of charge/discharge, but with a huge caveat that this rate of discharge/charge is relative to the discharge/charge rating of the battery. So discharging a battery at 2C or 3C that is rated for only a 1C discharge would lead to premature degradation. But discharging that same battery at 0.5C would actually make it last longer. Float voltage is indeed different on any Lithium batteries, and there shouldn’t be constant voltage applied. My Victron solar charger disconnects the charging when the batteries are full (programmable) and then periodically checks the voltage and if it drops reconnects the charger. I can also program what voltage the charger converts from “bulk” charge (fast) to “absorption” charge (slower). I have mine set to do up to about 85% on bulk mode, then on up to 100% on absorption mode. On a boat you should always follow the “rule of 3rds”. 1/3 out, 1/3 back, 1/3 in reserve. I’m going to repeat the most important part KEEEP 1/3 IN RESERVE. So while it’s not advisable to regularly go below 33% on your boat batteries, it will not hurt your LFP’s if you do. |
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Re: Cells (modules) are dying.
? ?Anton, yes the big no-no with lithium chemistry batteries is to leave them high or leave them low. Certainly charge them to 80% and discharge to 20%. Or target a little narrower band (70%-30%) if you want your batteries to last 20 years or more. An occasionally wider band (100%-10%) is helpful with many BMSs (the edge of the performance envelope has more obvious voltage changes, and some % of BMSs only do "top-balancing"). Just don't leave them high or low. A minute is inconsequential, an hour adds up, a month would shave years off their lifespan, and a year would likely kill them. The time spent at naughty State Of Charge levels (the ballpark of over 95% or under 5%) savages battery lifespan. And certainly no trickle charge... that just leaves them high all the time. ? ?I would be very reluctant to drain lithium chemistry batteries all the way to zero. If it keeps me alive, I'd do it, but I'd have to assume it kills or cripples them within minutes or hours. ? ?And yes, you are in the ballpark with cycle count. Each manufacturer probably counts cycles different, even to the point of not counting any cycles if you stay between 60% and 40% (guessing, because the chemistry is so stable at these voltages in room temperature). |
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Re: Cells (modules) are dying.
I think that the charging to 100% is only detrimental to NMC batteries, not LFP. But you are correct that all the batteries have about a 10 year lifespan (max for NMC, min for LFP). The thing to remember about the cycles is that the cycle rating is for degradation down to 80% of original capacity. This is still a very usable battery if this happens before your 10 years ends. Most of the NMC batteries are rated around 2000 to 3000 cycles and LFP around 4000 to 8000 cycles. The 80% to 20% use/charging is to prolong the cycle life of NMC batteries because the NMC’s get most of the charging/discharging degradation in this first and last 20%. The cycle rating is so large on LFP’s that there is no need to prolong the cycle life because they will age out before they reach 4000 cycles. And they don’t seem to suffer near as bad degradation in these First and last 20% ranges. From everything I have read the main detriment to life expectancy is rate of charge/discharge, but with a huge caveat that this rate of discharge/charge is relative to the discharge/charge rating of the battery. So discharging a battery at 2C or 3C that is rated for only a 1C discharge would lead to premature degradation. But discharging that same battery at 0.5C would actually make it last longer. Float voltage is indeed different on any Lithium batteries, and there shouldn’t be constant voltage applied. My Victron solar charger disconnects the charging when the batteries are full (programmable) and then periodically checks the voltage and if it drops reconnects the charger. I can also program what voltage the charger converts from “bulk” charge (fast) to “absorption” charge (slower). I have mine set to do up to about 85% on bulk mode, then on up to 100% on absorption mode (3.6V per cell for me). On a boat you should always follow the “rule of 3rds”. 1/3 out, 1/3 back, 1/3 in reserve. I’m going to repeat the most important part KEEEP 1/3 IN RESERVE. So while it’s not advisable to regularly go below 33% on your boat batteries, it will not hurt your LFP’s if you do. |
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Re: Cells (modules) are dying.
If you read too much about lithium batteries it just makes you paranoid!
I am not a chemist, so take this with a grain bag of salt, but from what I read I understand that lifepo4 and NMC batteries have a calendar life, which is negatively affected by storage at higher states of charge and higher temperatures but also a cycle life which is negatively affected by charging to higher voltage and discharging to lower voltage. and of course number of charge cycles. What constitutes a charge cycle is hard to pin down. 100% to 0 would definitely be one, but 70-30, then 90-50, then 65-36, etc.? I imagine 100%-0% counts as 1, but does 70-30 counts as .4 of a cycle? I doubt it’s linear and likely only quantifiable by extensive testing and only valid for that battery types size etc.? The thing that makes me paranoid is that I read somewhere that if current is pushed into a lithium battery, even a tiny current, even if the voltage doesn’t go very high, if done long enough, ?it will overcharge and ruin the battery. ?That is to say there is no safe “float” voltage. Once charged, stop charging until some energy has been used. So it seems to me that traction use, where the battery is charged then disconnected and used, is a simpler situation, but solar charging must be setup carefully so as to not hold the batteries at a high state of charge.? I have decided that the best policy is to avoid holding at high voltage ever, but just use as necessary and convenient and not worry too much. Have a large enough battery that you don’t have to use 100% of its capacity every day.? With lifepo4, if not held at high voltage with solar, service life should be decades if rarely drawn down below 20%.? anton |
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Re: Cells (modules) are dying.
Nominal is a funny word. The relevant definition for batteries is, "Existing in name only; not real." For instance a "12 volt" lead acid battery is the name, but the voltage should be 12.5v or 13.7 or 14.4 when fully charged or when on life support or when charging (respectively). These voltage values change by manufacturer, by sealed or flooded, lithium or lead, by intended use case, by longevity requirements... the list really does go on and on. So point 1 is to start with the particular recommendations of the manufacturer for fully charged voltages and for storage voltages and for charging voltages. Point 2: the idea of rust, deterioration. Humans deteriorate; metals deteriorate, some faster or slower than others. For every battery chemistry, there is a slowest-deterioration temperature and voltage. That voltage is chosen for how lithium chemistry batteries are shipped and stored. If the shipping voltage was any higher or lower, the batteries would degrade internally faster. So when you fully charge the batteries, use them quickly in hours or days, not slowly in weeks or months. The same use-it-or-lose-it idea also applies to batteries below their shipping voltage. In other words, for optimal longevity, minimize time spent above or below the shipping voltage. The bigger the deviation from the shipping voltage, higher or lower, the shorter the overall lifespan of the battery. That is why many people normally only charge to 70% or 80% of full, and then only right before they are going to use that particular electric vehicle or device. After use, leave at or very near shipping charge voltage. If you need a 100% charge every once in a while for maximum range, all the better (because it helps the BMS stay calibrated). Question: while a lithium chemistry battery is being drained or charged, does it also degrade, or does it only degrade while sitting idle? I assume the active chemical reactions of charging or discharging take precedence over ambient degradation, so I'm guessing lithium batteries only degrade while sitting idle. Any chemists? |
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