Hi all,
I have occasional IMA lights, not persistent, but after driving it does light up.
After checking, I found that most paired sticks on my HCH2 had 16.5V, few had lower voltage of 16.0-16.1V.

Since these are just few sticks of overall seemingly good battery, I am wondering if I can just replace those sticks (local hybrid repair has few such sticks) and they will pair them just like originals, not for free of course.

Since mostly IMA batteries replaced by set of batteries, I was wondering if such partial replacement was done before and what were the results.

 

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I do it frequently based on my own testing process. Unfortunately, just checking voltage tells you almost nothing about the state of the subpacks. Resting voltage of low capacity NiMH packs vs. healthy packs is very, very close.

Check my sig for the DIY grid charger/discharge. Yes, it's only a parts list, but hooking everything up is a no-brainer. Your pack will likely benefit from a re-balance via grid charge/discharge. Since the IMA fan requires a PWM signal to drive it, you have to use my charger outside of the car.

If you want to go with a commercial product, Hybridautomotive.com sells a quality grid charger and simple discharger. Much more convenient as you don't have to remove it from the car since it has a built-in PWM controller for the fan.

Lastly, Even if you successfully replace some bad ones, your pack will still be horribly imbalanced and will suffer from reduced capacity.

Good luck,

Steve

 

Keith,
thanks a lot for great answer!!
It does clarify a lot of points and is very valuable.
I decided to give up the idea.
Buying or making a discharger is sort of difficult for me.
I also had a very bad experience of buying a replacement iMA battery online recently.
I am thinking of my last resort as buying a specialized Optima 51R battery.

 

Not sure how the Optima battery comment applies, but if you're talking about replacing the 151R battery with a 51R battery, I recommend it and have done it on both my HCH2.

 

Yes, exactly.
I had bought another battery, smaller, and it has given me a lot of IMA lights.
Don't know much about deep charge batteries, but my give it a shot