4 cell Battery Assembly Question

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I have 4 brand new LC-R067R2P1 battery cells (6V,7.2 Ah) which I plan to wire together into a 12-volt glider battery (2 in series, and the series string in parallel).
All 4 cells have the identical notations on their cases. Each cell was labelled by the seller: "Top Charged 09/13".
I measured each cell (soaked for days at 72 F) and all 4 of them read 6.32 v on my Fluke DVM.
I make the assumptions that all 4 cells are in an equal state-of-charge, and I can just parallel them and then charge them as a battery and they will be balanced.

My other option would be to charge each of them fully, rest them for few days, measure them and hope that they now in equal state-of-charge.

Any comments?

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Should 1 of the 4 batteries fail by short-circuiting of even just one element (each is made of 3 elements, for 6v output), then the pair of normally working batteries would very quickly discharge through the faulty pair (which would have become a 10v battery instead of 12), overheating both.
May be a rare occurrence, but you can only prevent heat damage by fitting 2 correct size fuses.
I personally believe you can charge them all at once, when the batteries are in good health, with no problems. You may surely separate charge each of the two 12v sets, as well.

For example, DG motorgliders have exactly 4x 6v batteries, each 12v pair being connected to the other and to the main system, including a charging circuit, via a lead string fuse.

aldo cernezzi
www.voloavela.it

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If you have time and a good charger (Pb with float etc), I would charge them individually to ensure they are in the same state and then check them(should be done with a load) Easy enough to do and wont take long if they were topped back in Sept. Then assemble.

[SoaringXCellence]

Let's get our terms correct; the Battery has 3 cells in series for a total of 6V, nominal. We take two BATTERIES, in series, a total of 6 cells to make 12 volts. This is EXACTLY the same arrangement as any other Pb-acid based battery we assemble. Doesn't matter how we make the 12V, 6x2V individual cells, 3x4V batteries or 2x6V batteries. The 12V battery runs the same risk of shorted cells, unbalanced charge and total destruction. Using the same capacity AHr for each cell or battery in the assembly is critical to the whole longevity of the battery, but the assembly, up to 12V is really for the convenience of using of-the-shelf chargers.

I'll date myself here, but I remember assembling one 12V battery and one 2V cell to get 14V to put in the glider. The old radios were useless if the voltage dropped below 12 volts and just keying the mic would drop the voltage too low if you used a 12V setup. It was almost impossible to find a 2V Pb-acid charger in the late 60's.

[Dan Marotta]

I still use a 14 volt battery as the main power in my LAK-17a. It's made up
of 2 x 4v and 1 x 6v batteries in series. It came originally with my LS-6a
back in 1992 and the batteries are contained in a nicely TIG welded box
which holds them in a long line. I also got one of those big black smart
chargers that used to be advertised in Soaring Magazine (in either 12- or
14-volt ranges).

When I got the LAK, it had 2 x 12 volt batteries, a long, skinny pack in the
vertical fin and a standard 12 volt battery in the baggage compartment. It
also came with one of those big black smart chargers as above. Now the 14
volt battery is the main and the other two are for longer flights. BTW, I
need to replace the batteries in the tail pack.


"SoaringXCellence" > wrote in message
...
Let's get our terms correct; the Battery has 3 cells in series for a total
of 6V, nominal. We take two BATTERIES, in series, a total of 6 cells to
make 12 volts. This is EXACTLY the same arrangement as any other Pb-acid
based battery we assemble. Doesn't matter how we make the 12V, 6x2V
individual cells, 3x4V batteries or 2x6V batteries. The 12V battery runs the
same risk of shorted cells, unbalanced charge and total destruction. Using
the same capacity AHr for each cell or battery in the assembly is critical
to the whole longevity of the battery, but the assembly, up to 12V is really
for the convenience of using of-the-shelf chargers.

I'll date myself here, but I remember assembling one 12V battery and one 2V
cell to get 14V to put in the glider. The old radios were useless if the
voltage dropped below 12 volts and just keying the mic would drop the
voltage too low if you used a 12V setup. It was almost impossible to find a
2V Pb-acid charger in the late 60's.