Kent and Steve,

Thanks to both of you for your input.? It helped a lot.? Here is what I am going to try as a variant from your attached video, Kent.

I am going to feed my 18 volt no load 15 watt solar panels to LM2596S bucking modules to provide 5 volts DC.? Then I am going to do as shown in the video feed the 5 volts to TP-4056 Lithium ion charge modules.? These will then be hooked to individual 18650 battery holders.? Consequently I'll then be able to charge each cell individually and not worry about balance nor over charging the cells.

Reading some of the feedback from some of the purchasers of these cheap modules, you can find some bad ones.? I have ordered more of them then I need so if there are a few bad ones I'll have spares to fill in as needed.

It appears my only draw back to all this is I'll have to remove the cells from the user battery pack when I want to charge the cells.? (If I wear out the individual battery holders I'll replace them with new 30 cent holders!)

Again, thanks a million to you two guys for your advice.? (You both are smarter then you look!)

Lee

w0vt, w5drc

I am going to make up battery packs using four 18650 batteries for my qrp rigs.? How many diodes I will place in series with the pack's output will be determined by the rig used.? I have decided to have the option of charging these packs using solar power besides from house mains.? That presents a problem on how to solar charge them. I have decided to try the following using cheap Chinese models found on Ebay.

I am going to feed my 18 volt no load 15 watt solar panels to four LM2596S bucking modules to provide 5 volts DC to each charging module.? Then I am going to feed the 5 volts to four TP-4056 Lithium ion charge modules.? These will then be hooked to individual 18650 battery holders.? Consequently I'll then be able to charge each cell individually and not worry about balance nor over charging the cells. (These modules are cheap.)

Reading some of the feedback from some of the purchasers of these cheap modules, you can find some bad ones.? I have ordered more of them then I need so if there are a few bad ones I'll have spares to fill in as needed.

It appears my only draw back to all this is I'll have to remove the cells from the user battery pack when I want to charge the cells. (If I wear out the individual battery holders I'll replace them with new 30 cent holders!)
Lee
w0vt. w5drc

18650s are a good option and there are many sources new and used...

The key to charging a pack of series cells in the BMB or BMS.?

The BMB is Battery Managemant Board and the general function is to keep from?
charging to too high a total voltage, monitor individual cells for overvoltage,
undervoltage,?and also monitor over current for shorts.? The undervotlage
keeps from over discharging the cells and damaging them.? Over discharge
and over charge are fatal to the batter as it shortend life and can even cause fire.

The BMS or battery management system is all of the above but add two features.
One being it will equalize any high cells and also provides the charging circuit.
The latter allows for a voltage above a certain value and it regulates it for charging.

Generally its best to use the right charger for the battery lacking that any
constant voltage constant current (CV/CC) source properly set will work well.
The voltage is set to the max full charge voltages specified for the combined
cells (battery) for example for LiPo typically a four series cells its 16.8 or?
just slightly under (16.7).? Unlike NiCd or NiMH Lithium cells are not damaged
by less than full charging.? The current setting is battery dependent and I use
typically .3 to .5C (some are allowed more) so a 2800mah cell/battery charge
rate of 1.4A is reasonable.? Lithium cells do not like trickly charging, when
charged discontinue charging (most high end chargers do that).

I have many packs I'e made up for various radios and such.? An example is
a 11AH for my FT817.? It is 12 cells connected 4x parallel by 3x serial 4P3S
using LG 2800 mah cells for 11AH and 12.6V at full charge and exhausted at 9V)
and will run that radio for a very long time.

To charge with solar power you use the same basic charging system save for
the panel is the DC source.? Ive found the low cost CV/CC switch mode power
converters to be useful as they can accept the open circuit voltage of a
12V(nominal) panel that approaches 22V and will regulate it for both current
and voltage.? The panel?determines the max charge rate as often the pack an
accept more then the panel can produce.? For example most 20W panel that
is about 1A? but my 115W panel that closer to 6.8A.? The regulator can run
then in constant current mode for the battery in use.? One thing to note?
the best charge current is one that allows the panel to run at its best
power point which for most is 17-18V.? AS I said I use the switching
power converters so the do a power in to voltage and current out?and
the best charge rate wil vary for the size of the panel and the amount
of sun it receives.

There are charge controllers for lithium batteries, they must be matched
to the chemistry in use. (LION, Lipo, LIfePO4, A123... others.)
Do not use a charge controller designed for lead acid or gel cells.

Allison

Hi Juan,

have not heard any signal unfortunately. Tried to call as well. Maybe too early and band is pretty calm now.

Thanksfor trying

73
Martin

Hi Juan,

the band seems to be pretty dead now. What time would you suggest. Maybe around 18:00 UTC ? 14,060?

73
Martin

Hi,

the contest just ended and I captured very little QRP activities. Fortunately the Marconi Contest was on as well and the QCX on a GP abt 10 m up did very well on 20 m.?
88 QSO's and 26 countries including W, Ja, PY and VK. Nothing to complain about that I believe. My CW ist still a bit rusty and the decoder was a great help for these super QRQ guys. Its funny, the decoder seems to read preferrably QRQ.?

73?
Martin?
DK3UW