I am purchasing an 08 Tahoe Hybrid. The battery is under warranty and part of the deal is that they will replace the battery, but to do that the service center has to find that the battery needs to be replaced, which I believe it does. I believe that it is not holding a full charge. I don't believe they are putting any work into this. I tailed the vehicle this morning and they took it for a test drive and parked it. Does anyone have access to the service manual or know how to test the battery (either me or the service shop) so I can go to them with info and tell them exactly how to demonstrate the batteries diminished capacity?

Thanks

JT

 

These NiMh batteries aree very robust. I doubt there is an issue. Yes most dealres have no idea of how to test one.

Without a scan tool it is very difficult to "test" the battery. What clues if any does the vehicle give you to suspect the battery?

 

Thank you very much for the quick reply! I finally found the a service guy that knows almost everything about these vehicles. You are right, there was nothing wrong with it. I was concerned because the vehicle had been sitting on the lot, and it didn't go very far on battery power. The tech went through almost everything with me, hooking up the scan tool 2 and monitoring the battery, both running and not. Then he took me for a ride with the scan tool and monitored the different values. Then he took me for another ride showing me how the vehicle should and was performing. He was excellent. The only thing he didn't know is how to deep cycle the battery. Don't these vehicles deep cycle every 10,000 miles or so? Can't you tell it to deep cycle with the scan tool 2? I just didn't know the exact button pushes to tell him. Otherwise I am completely satisfied with his diagnosis.

 

If you now have a good relationship with the tech - see if you can get some of the CAN codes from him, so that we can plug them into our scangauges and monitor some of these parameters ourselves!

 

Unfortunately the tech most likely won't have access to the CAN codes. He just has the interface tool.

Winchester: you do not need to deep cycle the battery. In fact the manufacturer of the battery, Panasonic, prefers to keep the battery about 50% State Of Charge SOC plus or minus about 5%. Their reason is lenght of life. Odds are that your battery will out-live the engine and both should go over 200k miles.

 

Any replacement this early would most likely be warranty. Also, if you can find a remanufacturer of the GM packs, please let me know.

I have "other" uses in mind for the durable NiMh that the Prius and GM batteries use.

From what I've seen these batteries in general will outlast the engines. So much for the nay sayers. Take a look at the Toyotas over 10 years old on original batteries. The NiMh of late is even better.

 

I have a 2 year old dewalt NiMh that when fully charged lasts about 3 minutes. Very robust because it's got 600 volts. that's assuming 2 volts per cell would give you 300 individual batteries wired in parellel so if one or two go out you would never know. My plan is to take a voltage reading at the disconnect and try to figure out how many are toast.

 

Lost me there. 600V in a power hand tool? I have got to get me one of them! Don't drop it on the bath tub.

 

I'm thinking the gentleman was talking about 600 watts, as opposed to volts.

 

I was comparing an 18 volt NiMh power tool battery to a 600 volt NiMh hybrid battery
An 18 volt power tool battery has 9 cells at 2 volts each. 9x2＝18 volts
A hybrid battery has 600 volts. Assuming 2 volts per cell 600 divided by 2 ＝ 300 cells inside the battery. let's just say you have 10 bad cells inside the battery. 10x2＝20volts. Which would make a voltage reading of 580 volts at the battery confirming a 10 cell loss.

think of it as a modern string of Christmas lights. Not the kind that if you pull out 1 bulb they all go out but a string in which if a bulb burns out the rest stay working. Not the string of lights has 600 bulbs all clear glass. And 200 of the bulbs burn out. You would still have a working string of 400 bulbs. But would they be as bright? NO they wouldn't be. that's why a dealer can say we have never had a battery fail. What is their standard for failure. My Dewalt battery lasts 3 minutes and I consider that a failure. But someone else might say its still good for 3 minutes. With no standard to compair to we just don't know. I hope you understand what I am trying to say now!!