# Battery Pack amp draw



## ZeroGasoline (Jul 30, 2008)

To my understanding, any battery chemistry (lead, lithium, nicad) will suffer to some degree from high amp draws.

It will all depend on your battery pack. For example: many good quality lifepo4 batteries are rated for 10c bursts - so if your batteries are 100Ah, then you would be inside of proper operating range when pulling 1000w (100Ah * 10C = 1000w). Lower quality lifepo4 batteries are rated closer to a 2 or 3c burst - so pulling 1k from a 100Ah battery would significantly effect it's longevity and overall performance (100Ah * 3C = 300w).

I'm less certain with c ratings for lead batteries. However, the peukerts effect would definitely be a major player in this scenario. As you mentioned, those high amp draws significantly reduce your overall range, which is what I'd expect. Find out what the C rating is for your batteries, and multiply the C rating by the rated Ah of the battery - this will give you the max amp draw you should throw at the pack for any length of time.


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## F16bmathis (Jun 6, 2008)

Thanks for the info,

All I can find so far is a rating showing 75 amps drawn for 115 minutes. (Trojan T-105's)


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## major (Apr 4, 2008)

F16bmathis said:


> I have a Zilla and a Curtis 1231C. With the Zilla, I can pull 1000 amps, the Curtis 500 amps for a short time. I have a 144V, 225AH Trojan 6V pack. I was told that the pack should only discharge at around 2-300 amps.
> 
> I really want to go back to the Zilla, can anyone give me advice that simply states its OK to power out 1000 amps out of my battery pack without destroying it. (please feel free to lie here) By the way, powering out 1000 amps is great for showing off an electrics abilities, but wow does it reduce range.


Hey F16b,

You do know that motor amps can be greater than battery amps, right? And, I think you can set the limits for each with the Zilla. Showing off is likely done by smoking the tires or accels off the line. This requires high motor current, but not necessarily high battery amps.

As far as high current from Trojan 6V GC batteries, I wonder about that 2-300 amp tale. I used them in my eJeep and regularly pulled over 500 amps. You can't really pull that much current for very long. Well, unless you're going fast up a real long hill.

Regards,

major


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## F16bmathis (Jun 6, 2008)

I have my ampmeter through the pack to the controller, so the amps was from the pack. I guess I should have played with the Zilla's program, but was unsure of how to access it. Guess I have to get to reading the manual...

Only problem I've seen so far is the acceleration means less distance, BUT, with the Curtis, I achieved the same distance as when I was using 500 or less with the Zilla. I'll see what happens when the weather gets warmer... Or finish my battery warmer system.


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## notnull (Jul 30, 2008)

My advice is to check the voltage under load. I try not to let the voltage under load fall below 10.5V per battery and 10.0V per battery is the absolute minimum for me. I run a 120V pack and under hard acceleration of 600A, my pack falls to 105V. If I crank it up to 700A it drops below 100V, so I turned it back down to 600A.

My advice is based on numbers published from companies like Odyssey that terminate their high current test at 10.5V. 

So, do some testing and see how much curent you can get before dropping below 126V for your 144V pack.

Steve


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## F16bmathis (Jun 6, 2008)

Steve,

Thanks, didn't think of it that way. I knew that when getting below 126V for a 144V pack, it is considered dead, but I didn't think that when not empty, I should be good amp wise, till I get to 126V. I will check it tonight!


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## jaspersk (Jun 26, 2008)

I am still breaking in a new pack. I have roughly 20 cycles. This is what I have been using as my guide:

http://www.evdl.org/archive/index.html#nabble-td20994489

From Lee Hart:


> There is no current above which life suddenly falls. Instead, the
> situation is that battery life shortens as average current increases.
> 
> I'd use this for a rule of thumb for flooded or gel lead-acid batteries:
> ...


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