# Battery Pack Calculator (Spreadsheet)



## Ziggythewiz (May 16, 2010)

There's a dozen calculators out there, but yours does look pretty.

C would be easy to add, just have values for continuos C rate and Max C rate and have the calculator show max power for each.


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## MN Driver (Sep 29, 2009)

I agree with ziggythewiz on the continuous and max C rate calculations.
Voltage sag would be a bit tough considering that having real IR numbers that actually calculate well for sag is tough to come by. Manufacturer specs can't be trusted and I really don't trust IR tests from hobby-type charge/discharge units other than a comparison reference or sanity check. I usually like to go by real world results of 'at 80% SOC and whatever C from my 100Ah cells on a warm 70 degree summer day, my cell voltage is ... after 5 seconds of load' Also keep in mind a prismatic cell of 100Ah is going to be able to pump out a higher C rating than a 200Ah cell before it sags to the same point. Example the Buggy guy has small cells and pulls 8C to get the same sag that a 180Ah or 200Ah cell would sag to under 5C. I'm curious where Rickard's 57 cell 400Ah Escalade conversion will sag to, I'm thinking 88 cells of the 260Ah cells would outperform the 400Ah by quite a bit. ...probably wouldn't fit though but a higher voltage and smaller cells usually wins the performance game.

I tried to enter the details for some LiFePO4 cells in the top area but the fields that I expected to automatically calculate like wh/mile or kwh weren't filling themselves in. I undid the changes and left the lead acid figures someone else had in there before me.


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## Ziggythewiz (May 16, 2010)

It's pretty easy to get IR, maybe as more people get the JLDs we'll get more data.

You really just need a digital ammeter next to a DVM and you can record the readings at various values, or what I really want to do, record a video of it and correlate the values later onto a spreadsheet.


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