Lead acid battery balancing

[aab1]

As I've been saying my bike battery was literally dead, it barely lasted 1 km. I was going to spend $500 US on an nimh 12 Ah and charger but for several reasons decided not to and to get 7 Ah lead batteries for $57 instead (yes, that's $57 total, of $19 each for three 12 volt, 7 ah batteries).

The price was just too good to pass, even though it's nearly half the capacity, I may keep them on the bike just temporarely and then find another use for them, at least my bike has a working battery now!

My question is do I need to balance the 3 batteries before charging them togheter? For now I just plugged them in series and the original bike's charger is charging them, but is there a risk of cell reversal and that kind of stuff like with nimh packs? Is it dangerous to charge the 3 lead acids without balancing first?

At last my e bike's main problem - a lack of working battery - is corrected! I'm finally starting to get some hope!

Thanks

 

[Baboonking]

no it's not. Interestingly though, I've heard of many people either smart chargers or 3 individual 12 volt chargers in order to extend cycle life.

 

[andrewelectricbike1]

TNC scooters does a value 36v lead acid charger. The main issue with SLA is that if you discharge to 80% regularly the cells will only last a short number of cycles. Better to (over spec you amp hours with SLA) But hey $50 is £25 and if I only got 100 recharge cycles I still would be pretty happy!
Andrew

 

[BBB]

no it's not. Interestingly though, I've heard of many people either smart chargers or 3 individual 12 volt chargers in order to extend cycle life.

Do you mean to charge all the batteries individually before they go in the casing, surely not at every charge!

 

[Baboonking]

Basically its not necessary to this, unless you for some reason suspect your 3 batteries to be unbalanced for some particular reason. The advantage of charging each 12 volt battery with an individual charger is that each battery is always charged correctly. Over time if the individual resistance of the batteries changes then charging 3 batteries in series will result in some batteries being undercharged and some overcharged. In such a situaltion one week cell would eventually destroy the whole pack.


The other option is to charge in series and use a balancer such as this PowerCheq - Battery Equalizer