# 36V Curtis Controller with 48V Li-ion pack?



## xevion (Dec 26, 2020)

Pretty much the title. I just got these two motor controllers for free and have a 48V Li-ion pack. I'm fairly confident the controllers could handle the nominal 48V, but when fully charged the pack is going to be in the 60s. Anyone have any idea? I'm expecting to be pushing ~250-300A.























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## rmay635703 (Oct 23, 2008)

I do not know the absolute maximum rating of a 36v controller like that, the 48v version of the same controller will handle a 60v lead acid pack with an absolute maximum of 75v

I’m guessing your wanting to use a 45v nominal lithium pack like you would find in a Chevy Volt?

Considering those controllers are only worth about $99 used I would get a lightbulb and bench test the controller at various voltages to see if it shuts down.

Most Curtis controllers will shut down in over voltage situations and a minor over volt normally won’t damage only cause shutdown

YMMV, it is also possible you will just let out magic smoke, tread carefully if you can’t afford to loose it.









Curtis controller voltage upgrade


I have 1204x-4408 which is rated at 24-36v and 400 amps. I am looking for info on replacing the Mosfets with higher voltage units for instance IRF640's like those in the Curtis 1221 which is rated at 120v and 400 amps. I'm not sure what else would need to be upgraded. Cheers, Norm




www.diyelectriccar.com





It appears 60v is the absolute maximum so if it improves battery life don’t charge past that level


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## xevion (Dec 26, 2020)

rmay635703 said:


> I’m guessing your wanting to use a 45v nominal lithium pack like you would find in a Chevy Volt?


Yup, I'm powering it with two 7S3P modules from a 2019 nissan leaf.

I think I'll probably look to trade the two controllers I have for one that suits my needs (48V, 250A)


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## brian_ (Feb 7, 2017)

rmay635703 said:


> I’m guessing your wanting to use a 45v nominal lithium pack like you would find in a Chevy Volt?





xevion said:


> Yup, I'm powering it with two 7S3P modules from a 2019 nissan leaf.


But the nominally 45 volt modules of a Volt are 12S , and the pair of 7S3P Leaf modules are 14S, so the nominal voltage of the pair of Leaf modules is about 17% higher (plus or minus variations in cell chemistry between these unrelated cells).


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## rmay635703 (Oct 23, 2008)

brian_ said:


> But the nominally 45 volt modules of a Volt are 12S , and the pair of 7S3P Leaf modules are 14S, so the nominal voltage of the pair of Leaf modules is about 17% higher (plus or minus variations in cell chemistry between these unrelated cells).


Yeah that goes into the not recommended place the usable charge below 60v of charge would need to be identified and a nominal above 48v will put more stress on a controller of that type.

the 48v 1204has much more real world headroom and would be a better fit here


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## cricketo (Oct 4, 2018)

Maybe it's possible to pop the thing open and check voltage ratings on capacitors and mosfets.


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