Re: [EVDL] A123 Battery charging
I am contemplating to use the A123 cells in an application.
Does someone have a more detailed charge spec than the
datasheet on A123 website?
In particular, how much float charge is OK on these cells?
I could not find that on the website.
Cor van de Water
Systems Architect
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Second Life: www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Marty Hewes
Sent: Thursday, September 06, 2007 11:55 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] A123 Battery Feasibility
I think the capacitor bank for a shot of acceleration has merit, but would be significantly more difficult to implement because it is so different.
A cap loses voltage linearly with discharge. To use 80% of the charge in the caps, you need a controller that can still provide drive current when the caps have dropped to 20% voltage output. Either the cap voltage needs to start very high, or the controller needs to boost. I'm guessing that's a very different, and more expensive, controller.
Then the battery pack needs to recharge the caps which may need to charge to a significantly higher voltage than the batteries? I don't think that's a common or reasonably priced charger, although charging caps is probably a whole lot simpler than charging batteries. Just an inverter with current limiting?
----- Original Message -----
From: "Jack Murray" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Thursday, September 06, 2007 10:25 AM
Subject: Re: [EVDL] A123 Battery Feasibility
> Sure, but then what is the cost savings if you kill the power pack by
> charging and discharging it 100 times more than if it was a full pack?
Where does the 100 times more come from? I see two scenarios. Either the
power pack is made up of a small load of expensive batteries that can be
cycled many times, but don't carry enough charge to get sufficient range
(light but expensive solution). Or the power pack is made up of cheaper
higher capacity batteries but never discharged very deeply (cheaper but
heavy).
> Or the cost to replace the floodies from running them harder instead?
I'm guessing that since the acceleration current is primarily being supplied
by batteries designed to supply high current, the floodies shoud last longer
and not lose range due to Peukerts. I don't see how they would be run
harder?
> Or the extra weight being accelerated with a big heavy charge pack?
More weight than what? A combination of floodie and AGM should give you
more acceleration potential than an equivalent weight of all floodies, and
more range and life span than an equivalent load of AGM. I'm guessing that
since the hybrid would draw on each type to do what they were designed to
do, the result should be better than simply averaging all floodie and all
AGM numbers.
> My view is that a capacitor bank provides the biggest DIFFERENCE from
> batteries so it has a lot more potential to be exploited for some gains.
> But in any case, it is straightfoward (but still time consuming) to test
> any setup on a small scale to find out how it works, a computer model
> might be even easier.
A computer model would be great. But I don't see an inexpensive way to try
putting an advanced battery type in parallel with a floodie with a nominal
voltage maybe 10% higher. What is the cheapest deep cycle floodie
available? Maybe that and some power tool AA's? But mathematically I'd
think you could characterize charge and discharge curves of both, boost the
floodie curves 10%, and parallel them on paper so to speak.
Marty
> Jack
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I am contemplating to use the A123 cells in an application.
Does someone have a more detailed charge spec than the
datasheet on A123 website?
In particular, how much float charge is OK on these cells?
I could not find that on the website.
Cor van de Water
Systems Architect
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Second Life: www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Marty Hewes
Sent: Thursday, September 06, 2007 11:55 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] A123 Battery Feasibility
I think the capacitor bank for a shot of acceleration has merit, but would be significantly more difficult to implement because it is so different.
A cap loses voltage linearly with discharge. To use 80% of the charge in the caps, you need a controller that can still provide drive current when the caps have dropped to 20% voltage output. Either the cap voltage needs to start very high, or the controller needs to boost. I'm guessing that's a very different, and more expensive, controller.
Then the battery pack needs to recharge the caps which may need to charge to a significantly higher voltage than the batteries? I don't think that's a common or reasonably priced charger, although charging caps is probably a whole lot simpler than charging batteries. Just an inverter with current limiting?
----- Original Message -----
From: "Jack Murray" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Thursday, September 06, 2007 10:25 AM
Subject: Re: [EVDL] A123 Battery Feasibility
> Sure, but then what is the cost savings if you kill the power pack by
> charging and discharging it 100 times more than if it was a full pack?
Where does the 100 times more come from? I see two scenarios. Either the
power pack is made up of a small load of expensive batteries that can be
cycled many times, but don't carry enough charge to get sufficient range
(light but expensive solution). Or the power pack is made up of cheaper
higher capacity batteries but never discharged very deeply (cheaper but
heavy).
> Or the cost to replace the floodies from running them harder instead?
I'm guessing that since the acceleration current is primarily being supplied
by batteries designed to supply high current, the floodies shoud last longer
and not lose range due to Peukerts. I don't see how they would be run
harder?
> Or the extra weight being accelerated with a big heavy charge pack?
More weight than what? A combination of floodie and AGM should give you
more acceleration potential than an equivalent weight of all floodies, and
more range and life span than an equivalent load of AGM. I'm guessing that
since the hybrid would draw on each type to do what they were designed to
do, the result should be better than simply averaging all floodie and all
AGM numbers.
> My view is that a capacitor bank provides the biggest DIFFERENCE from
> batteries so it has a lot more potential to be exploited for some gains.
> But in any case, it is straightfoward (but still time consuming) to test
> any setup on a small scale to find out how it works, a computer model
> might be even easier.
A computer model would be great. But I don't see an inexpensive way to try
putting an advanced battery type in parallel with a floodie with a nominal
voltage maybe 10% higher. What is the cheapest deep cycle floodie
available? Maybe that and some power tool AA's? But mathematically I'd
think you could characterize charge and discharge curves of both, boost the
floodie curves 10%, and parallel them on paper so to speak.
Marty
> Jack
_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev
_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev
