How Many Lithium Batteries for 300HP?

by greg schramm
(Merritt Island FL)

How many of what size of batteries will it take to make a pack of lifepo4 batteries equivalent to a (300 hp) electric AC engine?

Hi, Greg -
Mike Collier from Lithium Storage says:

"Well...that question is like asking how much soda should you buy for a party. I don't know how many folks to expect and whether they will come thirsty.

First, electric motors are only measured in HP to compare them to gas engines.

But the HP doesn't give me enough to go by. I need to know the AC motor's recommended voltage. That will tell me the pack voltage for the vehicle and the quantity of cells needed.

Second, size...even more subjective. Things to be considered for an answer to your question are:

  • How heavy is the EV?

  • Will it be operating in a hilly neighborhood?

  • How long is the average commute desired?

  • What's the max range needed?

  • Will the AC’s Regen be used? (it could shorten the range.)

I often recommend folks asking that sort of question go to The EV Photo Album and search for similar EVs to the one they want to build. The working range is usually posted. And if not, the page lists the contact email address for the EV builder and most folks love to talk about their experience."

- Mike

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What About a Few Guidelines?
by: Dalmazio

Okay, but would it be possible to get some information on trade-offs and how to choose different battery pack configurations? Some variables to limit for simplicity:

- assume AC50 motor and curtis controller (very popular)
- primary focus on maximum range
- mixed city and highway driving
- terrain not too hilly
- donor vehicle 3000 lbs
- maximum range: ~100 miles
- average commute: 50 miles
- AC regen: yes, if it will increase the range (wouldn’t it always?)

Which battery pack configuration is most appropriate? How do choose battery pack configurations given the above criteria? Would you be able to provide a few sample configurations? Including Ah rating, pack voltage, kwh capacity?

Any guidelines would be great.


Hi, Dalmazio -

That sounds like a new VW beetle-sized donor, right?

Configuration depends on where you have available in your particular donor vehicle to put battery boxes that will store batteries safely and out of the way.

Lithium batteries from EV suppliers come in 100/180/200/300AH choices. The lighter end (100AH) comes with an acceleration tradeoff: the bigger batteries have more amps available to draw at a time.

AC regen is a given in a car, sure. It will help you regain some charge as you brake.

You can call Mike @ Lithium Storage at (801) 466-9213 for more help.

- Lynne

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