Good day to all! I have had our HCH for a few months, and we bought it with an IMA light on. So the other day I was bored and removed the rear seat and battery cover and tied some wiring to the terminals on the IMA battery so I could hook up my DVOM and monitor voltages, more for kicks and grins than anything. On the 200 VDC setting, I am reading 140-170 with the key on. When I shut the key off the voltage drops off steadily to 0. But the wierd thing...when I have the car running, it is in the 160-ish range, until it starts charging, and then it reads over limit, and still out of limit on the (I believe) 700 volt setting. Is this normal behavior? I am still learning about this crazy creature, but that seems odd to me. I tied my leads to the main power terminals on the battery, so I can't figure out why the voltage is bleeding off with the ignition off. I thought the power relays and such were outside of the battery itself. Any guidance would be greatly appreciated!

Rob

 

Rob,

With your IMA light on, the behavior at the terminals is unreliable.

There is a relay on the junction board of the pack. When 12V is cut, it opens, and you have zero V at the pack terminals.

What are you trying to accomplish? Are you just putzing around with it, or are you trying to fix it? I vigorously urge you to not subject yourself to unnecessary risk without a useful goal in mind.

What is your location?

What codes are being reported?

Is your 12V light on?

Status of master switch?

I recommend you avoid the back seat until you have read codes and have some idea of that the problem could be. Your probing has no diagnostic value whatsoever. The procedures to diagnose and correct an IMA fault are completely dependent on the codes reported and other secondary information gathered as dictated by the codes.

If you MUST continue to putz about with it, at a minimum, gather some useful data by measuring the tap voltages from the back of the connector that goes from the battery to the BCM (orange cable). You don't need to unplug it, just probe it from the back:

IGNITION OFF, MASTER SWITCH OFF



You want:
14-6
6-13
13-5
5-4
1-7
7-2
2-8
8-3
3-9
9-10

They should all be high 15-16V. They should all be as close as possible. Preferably less than 0.2V difference between highest and lowest.

 

I bought the car from a friend who had the light diagnosed as a pack. Not sure on the code though. It constantly recals while driving. I did figure out to tie my positive lead onto the terminal at the kill switch to get a reading with the key off. I made a discharger and discharged the battery tonight. That may have been a mistake. It won't show any charge or charging on guage, but the voltage has climbed to 51.

 

So i measure voltage between the pins listed? I suppose i jumped the gun on the discharge since I have not built a grid charger yet, but that wont be a hard project if I have to tackle it on a moved up time table.

 

Big mistake. Car expects tap voltages within a certain range. They are miles from where they need to be now.

Yes, but a waste of time now. It's helpful to know the operating conditions, but you've obliterated those.

You need to build a grid charger.

Code reading is always a must.

Good luck,

Steve

 

So a grid charge is the only solution to regaining any semblance of IMA operation? It is doing enough charging to keep the 12 volt up while driving, so i can still use the car. What would be required voltage wise to charge the sticks individually? And can that be done without physically removing the cells from the pack?

Rob

 

You killed your pack as far as the BCM is concerned.

You can install in "bypass" mode (link in my sig).

You need a NiMH specific charger or a constant current charger under 0.65A you can reliably control.

You might be able to hit each stick pair with a 12V charger up to 14.7V. 15 minutes or so on each pair (10 pairs) might be enough to bring them back into an operational range where the car can do something with them.