Charging from one 80 Ah 12 volt Pb battery at the time or two in series? - RC Groups
Jun 25, 2012, 02:45 AM
Bo Edström, Sweden
Discussion

# Charging from one 80 Ah 12 volt Pb battery at the time or two in series?

Hi,

Is it any advantage as far as getting more Ah out of source Pb 12 volt batteries if using two in series to get 24 volt and double Ah to charge from
compared to using one battery until it is drained and then next Pb battery until that is drained also?

I was thinking about the low voltage alarm that the charger announce - could it be that it is possible to squeeze more charging cycles when using two Pb in series since low voltage alarm shold not be there so early (I assume)?

I have two 80 Ah 12 volt Pb (lead) marine batteries at the field to charge with.
My charger is a Hyperion EOS 0720i Super DUO3 charger (2 x 1S-7S, 20A max, 1000W) and it can handle up to 28 volt input.
I mostly charge 6 cell 5200 mAh Lipo at the field.

So far I charge with one Pb battery, then when it is empty (charger complain about low voltage) I get the second Pb battery and continue to charge with that.

regards,
Bo
Last edited by bossee; Jun 25, 2012 at 02:50 AM.
 Jun 25, 2012, 04:26 AM Supersonic Engineering If yours is a 1000W charger, that's 83A at 12 Volt input, but only 41.6A at 24 Volt input, so two in series will last longer than the one. However, if you use 2 x 12V batteries, one after the other, then there should be little to no difference in energy available.
 Jun 25, 2012, 04:58 AM Bo Edström, Sweden GordonTarling, Thanks for answer. I think I will have to test to see if the low voltage warning from charger will let me drain the 2x12 volt Pb batteries in series little more then I use one battery and then next battery. I'm not sure how much a 12 volt Pb battery should be drained to not harm it's life but I think 30% (12 - 11.9 volt) left should be OK. 12,8 volt = 100%  12,5 volt = 75% 12,2 volt = 50%  11,9 volt = 25%  11,6 volt = 0% (all at room temperature) /Bo
 Jun 25, 2012, 10:49 AM Bart The high the current that you draw from a battery the lower the capacity you will get from your battery. So put them in serie and you will get more capacity from them. If the requested power is the same. Bart,
Jun 25, 2012, 11:31 AM
Registered User
Quote:
 Originally Posted by bossee So far I charge with one Pb battery, then when it is empty (charger complain about low voltage) I get the second Pb battery and continue to charge with that.
Depending what your low voltage warning is at you may be damaging your battery and reducing your capacity further. I would double check the data sheet for your battery to see how low it should be discharged.
 Jun 25, 2012, 03:43 PM RC Helicopter Pilot I would think from an efficiency stand point 24V (wiring the 2 in series) would be a way better way to use Pb batteries, if the chager work on 24V, which your does.
Jun 25, 2012, 06:04 PM
The 6 P principle works for me
Quote:
 Originally Posted by bossee GordonTarling, Thanks for answer. I think I will have to test to see if the low voltage warning from charger will let me drain the 2x12 volt Pb batteries in series little more then I use one battery and then next battery. I'm not sure how much a 12 volt Pb battery should be drained to not harm it's life but I think 30% (12 - 11.9 volt) left should be OK. 12,8 volt = 100%  12,5 volt = 75% 12,2 volt = 50%  11,9 volt = 25%  11,6 volt = 0% (all at room temperature) /Bo
AFAIK, if it is an AUTOMOBILE battey it is best not to use more than 25% of capacity another words, leave 75% of capacity in the battery

if it is a DEEP CYCLE(like a marine deep cycle) then you can use up to 50% of capacity.

 Jun 25, 2012, 06:48 PM Bo Edström, Sweden Hi, It is deep cycle Pb batteries I have but it is probably best to not drain them below 50% of capacity in the long run but maybe down to 30% ocassionally. /Bo Last edited by bossee; Jun 25, 2012 at 07:01 PM.
Jun 25, 2012, 10:15 PM
RC Helicopter Pilot
Quote:
 Originally Posted by bossee Hi, It is deep cycle Pb batteries I have but it is probably best to not drain them below 50% of capacity in the long run but maybe down to 30% ocassionally. /Bo
You mean down by 30% to 70%?

If you have 2, I sure would wire them together.
You will at least be able tto charge at twice the rate.
Your charger is limited with only 12V input.
 Jun 26, 2012, 03:13 AM Bo Edström, Sweden I mean so about 30% of capacity is left in the Pb source battery. Yes I know that with 24 volt as input to my charger I can charge with more amp and get the LiPo packs charged faster but I have today 7 amp set on each channel in the charger and that is fast enough for me, it let me fly more or less continous with my 3 LiPo packs 6 cell 5200 mAh when charging on the two channels at the same time. So I basically do not need to be able to use more amp when charing, just wanted to maybe squeeze out some more Ah when using the Pb batteries in series and get 24 volt as input to charger and that way avoid the low voltage warning (that perhaps is little early with just one Pb at the time). /Bo
 Jun 26, 2012, 07:18 AM Registered User Grimbeaver gave you some good advice; an easy way to ruin any Pb battery is to deep discharge it. Try to NEVER let it drop down below 11.9 volts under load. Generally, running the two 12 volt batteries in parallel will give you the most milliampere hours out when using a charger designed to use a 12 volt source and will be much easier on the 12 volt batteries.