a Bunch of SLA Battery related questions!

[august23]

I am trying to get my head around what is happening to my e-riding experience when using 2 different chargers for 2 different battery packs. one is with a slow 1.2amp charger. the other is a 2.0amp charger (both 24v). Obviously the high the amps, the faster the charge. But what is really happening? I was once told that I should stick to one type of charger per set of batteries to avoid shortening the life cycles of the battery. He also said "high amps in, high amps out and short charge time equals short discharge time". Can anyone confirm and/or elaborate on this?

another question about batteries: if I have 4 12v SLAs running in series to make 48v, which batteries are drained first? the ones closer to + ? or are they equally drained?

another question: say I have a 48v sla pack. if I charge it with one 48v 1.5amp charger, would it take the same amount of time to charge them as 2 separate 24v packs w/2 24v 1.5amp chargers?

another question: when shopping around for 48v battery chargers, I found some ebay listings that specified the amphours of the battery it should goto. like "48v 20ah battery charger" but it didn't specify the amps. would this charger work on 4 12v 10ah SLA batteries? if not...why?
(http://www.ebay.com/itm/48V-20Ah-battery-Charger-Scooter-bike-For-Razor-/350544097071?pt=LH_DefaultDomain_0&hash=item519e0e6f2f#ht_1428wt_1397)

And yet another! Overcharging: I have a Cycle Analyst and a volt meter that are both reading 39v on a fully charged 36v system (3x12v 10ah). Is this typical? is it bad? please elaborate.


Thanx!
Augie

 

[Trackman417]

When you series all the batteries they discharge at ROUGHLY the same rate. It is good, however, to check the individual battery voltages after a month of two of constant charging/discharging. You will be hard pressed to find a battery with a significantly lower voltage then the batteries in series.
a 48V 1.5 amp charger would charge just as fast as two 2V 1.5 amp chargers. When charging batteries, it is the how fast (amps) the charger can charge that will dictate how fast a specific battery will charge. The only thing that differs between those two chargers is the voltage they charge at. In this case the 48 volt battery charger would make more sense. You will be plugging in on plug instead of two, minimizing accidents.
Yeah the charger might work. I think there is a general rule when charging SLA, you should look that up.
The battery's will always be higher then their specific voltage hot off the charger, that is normal. There is no constant battery voltage when discharging/ charging battery's.
Wy go with SLA when you can get lipo with just a little bit more money, and the battery's will last three times longer then SLA. Not only that they are a good three times lighter as well.
I got this charger http://epbuddy.com/index.php?main_page=product_info&cPath=17_20&products_id=170
and four of these batteries http://www.hobbyking.com/hobbyking/store/%5F%5F20837%5F%5FZIPPY%5FFlightmax%5F8000mAh%5F5S1P%5F30C%5FUSA%5FWarehouse%5F.html
and I got a charge/ discharge harness from icecube, GREAT GUY! =D

 

[amberwolf]

One potential problem with using an SLA charger rated for higher Ah batteries than you have is that it typically can output higher charging current. If you use too high a charging current for an SLA, the electrolyte will boil inside, and vent moisture that you can't put back in, leaving the battery less capable than it was before. Doing that repeatedly will assure it's early death. (I speak from experience)

Usually if the current is high enough to boil it, you can hear it sizzling inside the battery in a very quiet room.

 

[Trackman417]

One potential problem with using an SLA charger rated for higher Ah batteries than you have is that it typically can output higher charging current. If you use too high a charging current for an SLA, the electrolyte will boil inside, and vent moisture that you can't put back in, leaving the battery less capable than it was before. Doing that repeatedly will assure it's early death. (I speak from experience)

Usually if the current is high enough to boil it, you can hear it sizzling inside the battery in a very quiet room.

Ohhh that sounds interesting
Would that be why every one says to charge SLA outside to vent the potentially explosive gases that can leak out? I thought is was SEALED lead acid?

 

[Ykick]

One potential problem with using an SLA charger rated for higher Ah batteries than you have is that it typically can output higher charging current. If you use too high a charging current for an SLA, the electrolyte will boil inside, and vent moisture that you can't put back in, leaving the battery less capable than it was before. Doing that repeatedly will assure it's early death. (I speak from experience)

Usually if the current is high enough to boil it, you can hear it sizzling inside the battery in a very quiet room.

Ohhh that sounds interesting
Would that be why every one says to charge SLA outside to vent the potentially explosive gases that can leak out? I thought is was SEALED lead acid?

SEALED under normal conditions and applications. Boiling Electrolyte isn't normal and the package design allows for venting to prevent/avoid explosions.

 

[amberwolf]

Would that be why every one says to charge SLA outside to vent the potentially explosive gases that can leak out?

Yes, exactly. Same with any lead-acid battery--hydrogen gas can be evolved out of the charging process; I guess this happens more with higher charging currents.

But it's really just water vapor that is the problem with charging SLA at higher currents than they are meant to be done at, simply because you can't (easily) replace that.

 

[Njay]

Battery University on L-A bat charging:

http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery

Use the lower A charger as much as possible for longer life. And never leave your L-A batteries discharged, simply charge them as soon as possible. A few days left discharged will totally ruin them.