6v 4.5ah Batteries

[dymaxhan]

Hey guys....this is my first post and I had a question about 6v batteries....
They only weigh 2lbs....what if I wired an 8s 6v battery pack?
Has anyone ever tried that because that would only weigh 16lbs and
it would be a 48v 36ah setup right? They're also dirt cheap...
Tell me what you think!! Thanks
http://www.amazon.com/Battery-Biz-Inc-Volt-4-5-battery/dp/B0000X5YE4/ref=sr_1_1?ie=UTF8&qid=1347653306&sr=8-1&keywords=6v+4.5ah+battery+battery+biz

 

[miuan]

In series, you multiply the voltage, not current/capacity. So they'd be 48V and 4.5Ah. Pretty useless. SLA batteries are well known for being by far the heaviest battery used on ebikes.

 

[shawn_1976]

You will destroy them very quickly

 

[dogman dan]

Welcome to the awful truth about batteries, good stuff costs$.

But what exactly are you needing to run? and for how far? $150 worth of lead is still a good deal for some things. Not many because of all the weight, but they can be a cheap and simple way to do shorter trips.

 

[amberwolf]

Hey guys....this is my first post and I had a question about 6v batteries....
They only weigh 2lbs....what if I wired an 8s 6v battery pack?
Has anyone ever tried that because that would only weigh 16lbs and
it would be a 48v 36ah setup right?

You would need 8s 4p for that, so 32 of those batteries. So it would weigh 4x what you estimate above. That's about 1lb per volt. But it's worse than that...


Depending on the load you put on them, you will probably only get at best half of the capacity of an SLA pack, so in reality you will need 8 sets of EIGHT parallel batteries, then wired in series, to get the capacity you want. So that's 64 of them, for about 128lbs of batteries.

One more problem is that SLA age quickly even sitting around unused, and the longer they sit discharged at all the worse the problem is. SOme times they can be desulfated, sometimes they can't, and SLA (vs FLA) are worse because you can't usually add water to refill them as it boils off in charging or overheating in high-C-rate use.

They're also dirt cheap...

For good reason.

But even individually cheap, they are not cheap to build the pack you want--even if you got full capacity from them, it would still cost you $320+ to get 48V 36Ah. Most likely it would be $640+ to do it because of probably having to get twice as many parallel as you'd think, to make up for Peukert losses.


So you have a pack that weighs more than the bike and as much as many adults do, and costs more than a similar-capability Lithium-based pack could, and probably won't last as long.

That's one reason they call SLA-powered EVs "lead-sleds".