# Small amount of batteries



## evnz (Jul 24, 2010)

I take it you know the battery is lead-acid and you in a city thats not that flat you may look at upgrading the charger and batteries maybe lithium 
I have seen other types like larger versions of a " d" battery you use in a torch i only sergest lithium bateries because there is less inturnal resistance 
eg if i got a 200 amp hour lead acid battery i could only get about 100 ah out under load the lithium is not so it would be at a gess 180 ah out and more ah means more power to ferther 
hope this helped
owen


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## Farcry (Jun 26, 2012)

So I know that they are 12V batteries, SLA, but what im unsure of is the amp hour rating is, and the discharge rate. I also dont know what the DZM stands for.

but yes Thanks Owen for getting back to me, I think your right about Lithium, but the only way i could afford to use them would be to make a pack from RC helicopter battery packs - ive seen some info on it, but not enough yet.



if the nominal voltage of my pack is 48v, for SLA batteries.
what would it be for Lithium/how many cells would be too few and how many would be too many?


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## Ziggythewiz (May 16, 2010)

You can replace 48V of lead with 15-16 3.2V (LiFePO4) lithium cells which is what we prefer to use here. I think most RC cells are 3.7V so you'd need ~13 of those.

A quick google says those batts may be 12 or 26 AH. Are there a bunch of batts in that box, or can you not open it? How much does it weigh?


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## Farcry (Jun 26, 2012)

Ziggythewiz said:


> You can replace 48V of lead with 15-16 3.2V (LiFePO4) lithium cells which is what we prefer to use here. I think most RC cells are 3.7V so you'd need ~13 of those.
> 
> A quick google says those batts may be 12 or 26 AH. Are there a bunch of batts in that box, or can you not open it? How much does it weigh?



Thanks for that Ziggy,

13/14/15 cells, sounds like it would require a custom charger?
i suppose 13cells could be 5x3cells at 11.1V each charged as 11.1v each.

the box/battory is sealed, white top with threded terminals. i could say it weighs 5- 7kg perhaps? (i will find that out in a few weeks)anks


thanks


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## Ziggythewiz (May 16, 2010)

You don't necessarily need a custom charger, anything will do if you can get the cutoff to match what you need or control the cutoff externally. You'll want to charge them all with a single charger, otherwise you'll imbalance the cells as your chargers won't be identical.

Yes, get the exact weight and since it's lead we can reverse figure the size of the old batteries.


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## Farcry (Jun 26, 2012)

well, now i have to do something! i turnd the key and found a problem, all4 battories, swalen as hell, gone, usless. so the only weight ill get from them, is at the scrap dealer.

there was a sereial number running along the lid that ended 10A.....


what are your thoughts on parallal charging? im dreaming up a series/parallel relay gizmo. parallel when de energised for charging, and then using one standard charger....11.1v say?


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## Ziggythewiz (May 16, 2010)

Just weigh the box before sending to the scrapper.

Especially with lithium, series charging is better than parallel. It's much better to leave all your connections in place instead of playing musical jumpers twice a day.


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## Farcry (Jun 26, 2012)

each 12v battery weighed 7Kg, i was right on the money.
well i weighed one at the workshop before taking them to the scrap merchant....whos scales came to a total of 25KG.......mmmm - any who.

ever seen a 55.5v lithium charger?


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## Ziggythewiz (May 16, 2010)

For that weight the 26 AH makes sense, so you could replace with 15 x 20 AH lithium cells for probably a 30-40% improvement over the original range, or go 40 AH cells (a more normal size from major brands) and more than double your range.

There are probably many chargers in that range, though they would likely be labeled as 48V chargers. 55.5V is a bit on the high side, most manufacturers would recommend a finish voltage of 54.75 and many of us go a little lower than that (for LiFePO4).

Have you started looking at any cells?


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## Farcry (Jun 26, 2012)

aahhhhhHA
so a charger advertised as a 48v charger, could still be good to charge 5 cells advertised as 11.1v each, in series. sound correct to you?

No I havnt been looking very hard at them..... but my options (according to my budget) are gna be SLA, or RC car lipos (and a charger)

i have got my hands on some more SLAs that are 20ah......trying to see if they hold charge at the moment.


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## Ziggythewiz (May 16, 2010)

Probably so. It just depends on the exact finish voltage. There are many kinds of leads and lithiums out there, and each is a little different.


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## Farcry (Jun 26, 2012)

speaking of which - ive made up a lead so i can take voltage readings of the charger while charging, or alone, or the batteries, and with this i have discovered the charger goes up to 60v (so 15v per 12v battery) but finishes up at 54v (or 13.5v per 12v battery)
so thats pretty useless!!! i want 57.6v in the finish, (14.4v per 12v battery)

so il take some photos, open up the charger and see if there is any pots i can tweak.


so i would say that the cause of the Green batteries swelling was due to age, causing high internal resistance, that tricked the charger and failed to turn the charger off.


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## Ziggythewiz (May 16, 2010)

That's a typical charge for 48V of flooded lead acid. To make it work with sealed lead acid or lithium you would just need to be able to turn the charger off with a programmable voltmeter.


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## Farcry (Jun 26, 2012)

Ziggythewiz said:


> That's a typical charge for 48V of flooded lead acid. To make it work with sealed lead acid or lithium you would just need to be able to turn the charger off with a programmable voltmeter.


which is typical, 54v or 57.6v?

i think moding the charger to do lithium sounds like the fast track to a f***up. (for me anyway)


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## Ziggythewiz (May 16, 2010)

My charger goes up to 2.55 VPC during the gas cycle, which would be over 60 for your size pack. If set to AGM it would do ~ 59V.

You wouldn't mod the charger to use it with lithium, you just control it. A programmable Voltmeter could trigger a relay that cuts power to the charger.


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## eco-ants (Jun 27, 2012)

An easy and cheap option might be a PING battery pack.
It comes with BMS and free 2A charger too 

I have a 48v 10Ahr pack from PING in my DIY e-bike and it's been very very good.
Totally recommend them !

http://www.pingbattery.com/servlet/the-2/lifepo4-lithium-ion-phosphate/Detail

Cheers
Ants


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## Farcry (Jun 26, 2012)

hey thanks for that, thats really good.
and so was it difficult to get them in the end? or was it simple?
this looks like a good option, only i dont have the funds right now to do it :-(


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## Farcry (Jun 26, 2012)

oh, and is that quoted in USD? 
it seems pretty good right now thow.


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## Ziggythewiz (May 16, 2010)

What's so good about the price? $2.2/ah?


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## Farcry (Jun 26, 2012)

i was meaning exchange rate.


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## Farcry (Jun 26, 2012)

eco-ants said:


> An easy and cheap option might be a PING battery pack.
> It comes with BMS and free 2A charger too
> 
> I have a 48v 10Ahr pack from PING in my DIY e-bike and it's been very very good.
> ...


 
how much was shipping and other costs at the time Ants?


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