# 96 volt pack to a 90 volt system?



## mikelenis (Mar 22, 2009)

hey there 
this is my first post.
I found a 1991 colenta pick up, here in holland, the pack is 15 x 6volt/160Ah, 90 volt agm and it is sulfated. I need new batteries and began to think of a lithium conversion. The closest pack voltage i can find is 96 volt. Would the extra 6 volt difference fry the controller and motor?

specs : Controller - Curtis 1221 
Motor - 90 Volt AC motor
11kW / 20kW (3min.)
137A / 300A (3min.)
Torque 35Nm

Is this enough info? or am I being to vague? please help with any insight, expertise or tips.

thanks mike lenis
1991 colenta in europe


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## Tesseract (Sep 27, 2008)

The Curtis 1221 is rated for use with a 120V battery pack, so you will be perfectly fine with 96V. 

Lithium iron phosphate cells are typically charged to 3.8V, have a resting voltage of 3.65V, and are discharged to 2.5-2.7V, so you could certainly string together 32 of them in series with the 1221. I personally like to see a little more voltage margin, but the Curtis controllers have been around for awhile and don't blow up too often.


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## DIYguy (Sep 18, 2008)

mikelenis said:


> hey there
> this is my first post.
> I found a 1991 colenta pick up, here in holland, the pack is 15 x 6volt/160Ah, 90 volt agm and it is sulfated. I need new batteries and began to think of a lithium conversion. The closest pack voltage i can find is 96 volt. Would the extra 6 volt difference fry the controller and motor?
> 
> ...


Others can chime in on this controller model as I'm not sure. It's unlikely that this will have any impact. 
Remember a couple things...for one, the voltage numbers usually quoted are "nominal". A "12 volt" battery will be higher than 12 volts fully charged... pack voltages are usually quite a bit higher as a result.
Secondly, your nominal battery pack voltage can be any derivative of a single battery voltage. In other words, 28 lithium batteries each having 3.2 volts would be 89.6 volts. (of course parallel and series connections are done with Lithium to get voltage and Ah ratings)

Cheers,


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