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  #1  
Old 06-07-2012, 04:18 PM
lkcl lkcl is offline
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Default small high current battery advice sought

hi folks,

i'm building a "heavy quadricycle" (350kg) hybrid electric vehicle (on-board generator) so i need only a small battery pack - 2.5kWh would suffice - and have chosen to go with a light-weight 48v DC motor (the PMG226).

peak power is about 10kW; peak ampage about 200A, but the average operating current is going to be about 125amps. the battery pack being 2.5kWh, that's 50Ah at 48v.

the problem is this: most batteries - almost all the ones i have found so far, if they're small, they only supply small current. a 50Ah battery pack typically has an operating current of say 20 amps *not* 125 amps: you have to go up to a 200Ah battery pack which is 10x heavier (400kg), 10x more expensive and 900% of such a battery pack is completely unnecessary for a hybrid vehicle anyway.

no, ultracapacitors are *not* an option: they're 1/10th the capacity and 10x the price.

so, my question is simple: has anyone encountered, anywhere, a battery pack or any batteries that are small but also have a high operating current, of around 100 to 125 amps?

thanks in advance,

l.
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  #2  
Old 06-07-2012, 05:11 PM
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Default Re: small high current battery advice sought

No the easiest to use but A123 20Ah pouches or even Headway cells would probably do the trick.
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Old 06-07-2012, 05:34 PM
lkcl lkcl is offline
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Default Re: small high current battery advice sought

hallo rwaudio, thanks for the recommendations. just looking up e.g. 48v 20Ah headway batteries:

http://stores.headway-headquarters.c...=Battery+packs

maximum discharge current is rated at 40A which is unfortunately 1/5th of what's needed. this is quite common, when investigating these batteries, to find this!

the A123 20Ah on the other hand looks much more promising. not bad pricing, either. silly people don't however state what the maximum current is.... or maybe they do, it's hard to tell from the datasheet (www.a123systems.com/prismatic-cell-amp20.htm)

it says discharge power 1200 watt, and if the voltage is 3.3v, that's wow - 363 amps! if that's correct then bloody hell that's damn good. at about 500g per pack, 48v would be 15 packs, which would be about 7.5kg - also damn good.

yeah, i think this might be exactly what i'm looking for. super!
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Old 06-07-2012, 05:35 PM
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Default Re: small high current battery advice sought

Quote:
Originally Posted by lkcl View Post
hi folks,

i'm building a "heavy quadricycle" (350kg) hybrid electric vehicle (on-board generator) so i need only a small battery pack - 2.5kWh would suffice - and have chosen to go with a light-weight 48v DC motor (the PMG226).

peak power is about 10kW; peak ampage about 200A, but the average operating current is going to be about 125amps. the battery pack being 2.5kWh, that's 50Ah at 48v.

the problem is this: most batteries - almost all the ones i have found so far, if they're small, they only supply small current. a 50Ah battery pack typically has an operating current of say 20 amps *not* 125 amps: you have to go up to a 200Ah battery pack which is 10x heavier (400kg), 10x more expensive and 900% of such a battery pack is completely unnecessary for a hybrid vehicle anyway.

no, ultracapacitors are *not* an option: they're 1/10th the capacity and 10x the price.

so, my question is simple: has anyone encountered, anywhere, a battery pack or any batteries that are small but also have a high operating current, of around 100 to 125 amps?

thanks in advance,

l.

Why not get 60 ah calbs, thundersky or GBS batteries? They're rated 3c continuous and 10C for 10 seconds....
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Old 06-07-2012, 05:43 PM
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Default Re: small high current battery advice sought

Quote:
Originally Posted by lkcl View Post
hallo rwaudio, thanks for the recommendations. just looking up e.g. 48v 20Ah headway batteries:

http://stores.headway-headquarters.c...=Battery+packs

maximum discharge current is rated at 40A which is unfortunately 1/5th of what's needed. this is quite common, when investigating these batteries, to find this!

the A123 20Ah on the other hand looks much more promising. not bad pricing, either. silly people don't however state what the maximum current is.... or maybe they do, it's hard to tell from the datasheet (www.a123systems.com/prismatic-cell-amp20.htm)

it says discharge power 1200 watt, and if the voltage is 3.3v, that's wow - 363 amps! if that's correct then bloody hell that's damn good. at about 500g per pack, 48v would be 15 packs, which would be about 7.5kg - also damn good.

yeah, i think this might be exactly what i'm looking for. super!
The headways you linked to are current limited by the BMS (they are e-bike batteries)

If you look at the raw cells the 8Ah "power" cells can do 200A peaks
http://www.manzanitamicro.com/produc...category_id=29

I'm using the A123's and yes they can put out the current!!
Headways would be easier to connect though and with the small pack you require could actually be a simpler/cheaper option.
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Old 06-07-2012, 05:44 PM
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Default Re: small high current battery advice sought

http://www.ebay.com/itm/16-A123-20ah...item3a6a1df080

right. found something. according to some of the photos on that ebay page the A120 20Ah is a "3C" continuous which i understand to mean that it can do "3x what the Ah rating is", in this case 20Ah, meaning it can do 60amps continuously.

but.. hmmm... http://www.diyelectriccar.com/forums...i-56862p3.html shows that these cells have been discussed before, contradicting what mr ebay above is saying. argh - need to find out more...
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Old 06-07-2012, 06:12 PM
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Default Re: small high current battery advice sought

Quote:
Originally Posted by lkcl View Post
http://www.ebay.com/itm/16-A123-20ah...item3a6a1df080

right. found something. according to some of the photos on that ebay page the A120 20Ah is a "3C" continuous which i understand to mean that it can do "3x what the Ah rating is", in this case 20Ah, meaning it can do 60amps continuously.

but.. hmmm... http://www.diyelectriccar.com/forums...i-56862p3.html shows that these cells have been discussed before, contradicting what mr ebay above is saying. argh - need to find out more...
Mavizen is the only authorized reseller of these cells (that I know of), if I was going to trust someones ratings I would trust theirs.
http://www.mavizen.com/A123.html

Mavizen is insanely expensive though so it might not be your first choice to buy from. And the cells found on the grey market may or may not live up to those specs. It's a tough call, but many people have tested them (including myself) and they live up to their specs. Even capacity as Mavizen states 18.5-20Ah.
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  #8  
Old 06-07-2012, 06:50 PM
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Default Re: small high current battery advice sought

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Originally Posted by rwaudio View Post
Mavizen is the only authorized reseller of these cells (that I know of), if I was going to trust someones ratings I would trust theirs.
http://www.mavizen.com/A123.html

Mavizen is insanely expensive though so it might not be your first choice to buy from. And the cells found on the grey market may or may not live up to those specs. It's a tough call, but many people have tested them (including myself) and they live up to their specs. Even capacity as Mavizen states 18.5-20Ah.
http://www.mavizen.com/A123/Special_Notice.html - some ebayers / alibabaers / taobaoers are likely to be intercepting quality-controlled *failed* items that are for recycling and passing them off as new, potentially placing recipients at risk due to catastrophic failure. mavizen is an authorised reseller.

ok. well - if the ones people on here have got are ok, and actually deliver and don't blow up, i'm happy with that
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  #9  
Old 06-07-2012, 07:09 PM
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Default Re: small high current battery advice sought

Quote:
Originally Posted by lkcl View Post
http://www.mavizen.com/A123/Special_Notice.html - some ebayers / alibabaers / taobaoers are likely to be intercepting quality-controlled *failed* items that are for recycling and passing them off as new, potentially placing recipients at risk due to catastrophic failure. mavizen is an authorised reseller.

ok. well - if the ones people on here have got are ok, and actually deliver and don't blow up, i'm happy with that
If you were the one legit reseller of these cells but they could be had all over the place for 1/5 - 1/3 the price wouldn't you try to scare people away from buying them?
No guarantee the cells are perfect, but for the price it's worth the risk to some people.
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  #10  
Old 06-07-2012, 07:15 PM
lkcl lkcl is offline
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Default Re: small high current battery advice sought

Quote:
Originally Posted by rwaudio View Post
The headways you linked to are current limited by the BMS (they are e-bike batteries)
ahhh, i understand.

Quote:
If you look at the raw cells the 8Ah "power" cells can do 200A peaks
http://www.manzanitamicro.com/produc...category_id=29
*whistles*

Quote:
I'm using the A123's and yes they can put out the current!!
Headways would be easier to connect though and with the small pack you require could actually be a simpler/cheaper option.
ehh, i'm all for simple
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