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helmy 03-19-2015 10:29 AM

HCH1 IMA battery voltage reading & reconditioning
I'm trying to diagnose IMA issue(s) on my 2004 HCH. I've had the dreaded IMA light on for some time now along with codes 1600 and 1570. The problem is compounded by the fact that the car is overdue for emissions inspection which it won't pass with the check engine/IMA lights on. The Honda dealer wanted $4k to replace the pack and also told me that the 12v battery needed replaced.

So my first question is what voltage should I read from the orange lugged terminals coming off of the battery pack with the switch on?

After reconditioning the pack I'm only reading 76V using my digital multi-meter set on 200 DCV. It seems like that is about half of what I should be reading.

This battery pack is only 2 years old, it was replaced by the Honda dealer 2 years ago under warranty. I've read that what they give you is a reconditioned pack but I'm not sure that is actually true.

I cycled through all 20 sticks in the pack and the numbers looked pretty good. I used 3 SkyRC IMAX B6 chargers. All sticks in the pack were reading about 5300-5700 mAh discharge and about 7800-8100 mAh charge. Because of that I only did 1 discharge/charge cycle before topping off the charge of all sticks and reassembling the pack.

After re-installing the pack I cleared the codes using a scan tool and also tried battery disconnect, but immediately when starting the car the IMA battery comes on. And when driving there are no indicators for charging or assist. It is throwing codes 1600, 1445, and 1570. The red 12V battery light generally comes on below 1k RPM. I have charged the 12V battery also, but not sure if it is actually due to be replaced or is just being drawn down by the weak IMA pack (or both).

helmy 03-19-2015 12:28 PM

Re: HCH1 IMA battery voltage reading & reconditioning
I hooked up some alligator clips to the voltmeter and connected them again to the IMA battery terminals. I now see the voltage approximately as follows:

~ 85V @ idle
~ 90V cruising at 40mph @ ~ 2k RPM
~ 160V @ 2.5k RPM
~170V @ 3k RPM

Do those numbers seem normal?

S Keith 03-19-2015 03:39 PM

Re: HCH1 IMA battery voltage reading & reconditioning
Please update your profile to indicate your location.

I regret to inform you that the SkyRC IMAX B6 you used tells you absolutely nothing about the suitability of the sticks. Yes, there are resources that document success with them, but the reality is that they can't apply a discharge load sufficient to truly test the sticks. Cycling sticks also give minimal improvement. You must deep discharge them (to near 0 volts) at low current to reclaim substantial lost capacity. Reversing these robust cells does not hurt them as so many references claim.

You need to buy the 500A carbon pile battery tester from harbor freight. You need to confirm that each stick can hold 5.4V under 90A load for 10 seconds.

Then you need to discharge at 10A and confirm that they have at least 5000mAh capacity at that discharge level.

Then you should recharge the sticks, wait a week and then discharge at 10A again to confirm that their self-discharge is not more than 1000mAh.

Note how none of those criteria say trickle discharge the stick at 700-900mA. A deteriorated stick can test great under those loads.

Assuming the pack was semi-functional before removal (would give limited assist and regenerative braking), concerning the voltage readings, did you turn the master switch back on? Did you reassemble and reconnect everything properly? What is the voltage at the pack with the car ignition off (not at the large terminals, those will be zero).

helmy 03-19-2015 06:14 PM

Re: HCH1 IMA battery voltage reading & reconditioning
Thanks Keith. Yes, I turned the master switch back on. Is there an ideal place to test the voltage on the pack without removing it?

Should I be concerned about the P1445 code (Bypass contactor) code?

S Keith 03-19-2015 08:38 PM

Re: HCH1 IMA battery voltage reading & reconditioning


The behavior you are describing suggests installation or assembly error.

helmy 03-21-2015 06:17 AM

Re: HCH1 IMA battery voltage reading & reconditioning
I will try to measure shortly from those points. What should I expect the voltage to be?

helmy 03-21-2015 08:37 AM

Re: HCH1 IMA battery voltage reading & reconditioning
4 Attachment(s)
This morning I replaced the 12V battery with a new one (it needed replaced anyhow).

I have removed the battery pack from the car again and carefully checked all connections and compared to original pics that I took and other pics such as the one on this thread. I've attached pics of the junction board side of the pack.

I did make one small but stupid mistake, which was to exclude the 4 8mm bolts that attach at the corners of the orange plate on the terminal side of the battery pack. It appears that those bolts do not provide an electrical connection and I am assuming that the exclusion of those bolts will not have any impact. I'd be happy if I were wrong about that. I have installed them now and will put the pack back together and back in the car for another test.

With the pack out of the car I measured 0V at the connections specified by the photo above with the master switch in either position. Is this the expected behavior with the pack disconnected? I will measure again with the pack connected in the car and the ignition off.

I measured 0 ohm across each of the 2 fuses and 12 ohm across the ceramic resistor.

With the junction board removed but the orange plates still connected, I measured the voltage across pairs of sticks and got almost exactly 16V for every pair.

helmy 03-21-2015 09:45 AM

Re: HCH1 IMA battery voltage reading & reconditioning
Put everything back in the car, disconnected the battery for 10 min and then reconnected. I read about 48V at those terminals with the key off.

IMA light is still on, at idle (1k RPM) the red 12V battery dash light is on. Still reading codes P1600, P1445, and P1570.

S Keith 03-21-2015 11:56 AM

Re: HCH1 IMA battery voltage reading & reconditioning
1 Attachment(s)
Again, if you were getting limited assist/regen function prior to pack removal, you assembled it wrong or something was damaged in the process.

With master switch on, you should get ~160V (16V * 10) at the terminals you've marked +/-. The range could be as low as 120V if the pack is completely discharged and as high as ~177V if the pack/sticks were fresh off a charger.

See attached.

helmy 03-21-2015 04:00 PM

Re: HCH1 IMA battery voltage reading & reconditioning
Thanks very much! That gives me something to go on. I will pull it apart again tomorrow and check what you've pointed out in the picture/diagram.

I was thinking that I was seeing 1/2 of the voltage that I should be seeing. But if I'm only seeing 48V it seems that I'm seeing about 1/3 of the voltage that I should be seeing.

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