The early ECU expects a 20-30 Ohm resistance on the PTC line. The patched ECU expect an infinite resistance on the PTC line.

An older battery with the PTC strips has a circuit resistance of about 20-30 Ohms. If you pair it with a patched ECU, you get 20-30 Ohms on a line where the ECU expects infinite resistance (open circuit) - IMA code thrown. The TSB involves removing the battery junction board and cutting out an inch of the wire that carries the PTC circuit - infinite resistance provided to ECU, no code.

A newer battery without the PTC provides infinite resistance on the line where the unpatched ECU expects 20-30 Ohms - IMA code thrown. The AFTERMARKET work-around is to "spoof" the PTC signal with a resistor. The DEALER solution is to charge the customer to patch the ECU. In both cases, 20-30 Ohms is seen on the PTC line, no code.

The fact that you were able to drive for a period indicates that the original combination of battery/ECU was correct. However, due to your test drive, after a sufficient period of time, battery deterioration was detected, and an IMA code was thrown.

A faulted PTC circuit disables IMA. The unpatched ECU is basically, "OMG! THE BATTERY PACK IS ON FIRE! DANGER WILL ROBINSON! DISABLE IMA! DISABLE IMA NOW!" Since IMA is disabled, the ECU can't assess if the pack is deteriorated.

This is all predicated on my belief the battery is bad as that's what's wrong 99% of the time. I don't recall you posting the codes from the IMA light on the way home.

I recommend you demand your money back and put this behind you.

 

I'll second that.

Unless the car was almost free, so that spending another ~$2300 (price + shipping + tax) for a new battery right now is still a good deal, or you just want to play around with this technology and do not need the car to work all the time.

 

but if I get rid of it i won't be able to contribute to these forums with such hilarious and knowledgeable people!

What does PTC stand for? In a nut shell its the temp sensors?

EDIT: https://www.greenhybrid.com/forums/f...-heater-29331/
So its a battery heater?

I took it right back before even getting codes read because I figured the less I drove it, and less time I had it before they got it back for them to see it had coded, the less they could claim it was something I did.

The effed up part is the whole reason I started shopping for a new car was because my trust 98 civic has developed a short that kills the batt over the weekend... if not for that I would have just kept that car.... but after being embarrassed by having to disconnect the battery all the time (its not good for it to drain at .6-1.0amps for 8-10 hours!) at work ... I decided to waste what you guys have all already said was too much $$ on this thing -- though I will say the blue books have these cars severely over valued compared to you all. (I'm inclined to think the books are wrong ...)

I was going to demand that the price be reduced to effectively 2500, and run until the IMA 100% stops... then evaluate at that time if it was worth another 2300, or my time and effort in finding/replacing individual sticks. But now you guys do have me thinking.... the IMA CTL module is now probably a cheap aftermarket part... strike against it....

It looks like the dealer is trying to jump title it so maybe I have a negotiation chip in that. Not the dealers name on title, its the original owner from WA state!! (Though they did give me another sheet which has them and 2 other dealers whose hands the car appears to have passed through so... I don't get it...

 

PTC = Positive Temperature Coefficient

There are 3-4 temperature sensors strapped to various cells to measure temperature distribution in the pack. It's impractical to monitor 120 cells, so they attached PTC strips running along each stick. If ANY cell gets abnormally hot, the 20-30 Ohm resistance will raise very quickly triggering a PTC circuit fault indicating a potential overheat.

They deleted it because it was just paranoia and cost. Nothing failed catastrophically.

The books are SO wrong. They don't factor in a $2000-3000 set of tires that WILL be replaced at some point as batteries are consumable wear items.

 

now the question is will the IMA and CEL trigger (for the bad batt, I've asked many people, local hybrid shop, bumblebee batteries, they all agree with you) before they try to hand it back to me.

 

Have them show you it's DTC ready with their scanner. That insures all drive cycle tests have been completed, and it's ready for emissions testing. That typically requires that you have driven the car 30+ miles.

If drive cycles are not complete and it's not indicating DTC ready, don't accept it.

Or... as I would vigorously encourage you to do...

Get your money back. You bought a problem, not a car.

 

You meant "IMA battery" and not "set of tires", right?

$2000-$3000 is really steep for Civic tires!

 

Yeah I looked them up after that!!

he meant 200-300 per tire I think, though I did find many for 150 (Delivered and installed)

Hell, I might put low rolling resistance tires on my regular car. 5% better gas milage for not that huge of an upfront cost increase.

 

The word everyone is looking for is "analogy"


KBB pricing kinda factors in traditional consumables like tires by stating that they must be in good condition or some similar requirement. Tread remaining is a good indicator of tire life, so that can get away with simply making a statement.


KBB doesn't factor in non-traditional consumables like hybrid batteries as there is no obvious way to predict their life.


IMHO, pricing SHOULD be done in a fashion similar to this:


1) Average miles of HV battery failure: for the sake of argument, let's say 150K.
2) Battery warranty, 100K in this example.


A car with up to 100K miles would not be influenced by the condition of the hybrid battery.


A car with 125K miles would have its value reduced by 1/2 the cost of the hybrid battery.


A car with 150K miles would have its value reduced by 100% of the cost of the hybrid battery.

 

Well.
Brought it home today. Beat on both the go and stop pedals as much as safety allowed.

The mechanic had replaced the IMA MOTOR unit. Showed me the old one sitting on the floor, old motor picked up what looked like brake dust (clutch?)

SOC acted properly as did ima. I thought it was supposed to charge while sitting at idle?

Never got it to charge all the way up, but also didn't try to drain them.

So new motor, and firmware with a resistor. The shop they took it to seemed pretty legit, he said he refurbished the ima battery too, had spare sticks from those lying around too.

Drove it 40 miles, going to do 20 more later tonight. It seems odd because the motor torque output seems to be more sometimes than others even while SOC is in top quarter and assist gauge is at full.

But no lights, auto stop seems to be working fine (though sometimes I think it thinks I'm in stop and go traffic and doesnt always shut down.

Hopefully its good! 1ill let you guys know.

Thanks so much for all your help thus far!