2008 Tahoe Hybrid sitting for months...

[bbOOmm]

My 2008 HyHoe was running just find although I think the original 2008 hybrid battery was starting to go. I was not getting much distance running on just the battery... far shorter than usual. I parked it in the fall, I didn't disconnect the batteries expecting my wife to run the engine once a month to charge up everything. Well, she forgot..... 4 months later and after several periods of below zero weather, she went to start it.... its completely discharged. Not even the electric locks work, not even a dim dome light.

I'm not home yet - I'm still out of the country for another 2 months, still lots of winter left back at home, so I'm going to assume that the brand new $200+ AGM battery is now frozen and trashed. What about the NiMH hybrid batteries.... can they freeze and be damaged if they are discharged and then exposed to freezing temperatures? I'm assuming the hybrid battery pack will be discharged since from what I understand, the hybrid system maintains the charge on the 12v system. So if the 12V is dead, the 300V must be dead.... and frozen.

Lastly, I did a search in the forum but I didn't find an answer. Maybe I used the wrong search words.

Since the engine is started off the hybrid battery pack, is there a way to put a charge in the hybrid battery from a charger. I'm sure I could figure out something going the reverse engineering route taking the lid off the battery pack and build a 300V+ charger... but really before going that route, I'd like to see if there is a proper way, like what the dealer would do if a hybrid Tahoe came in with dead batteries. It would be a real stup!d design if the engine uses the hybrid battery pack, and the engine is the only way to charge the hybrid battery pack. There's gotta be a way of charging the hybrid pack to get the engine started.

I had plans to replace the hybrid pack.... now it looks like this spring/summer will be that job. But till I get to it, the Tahoe needs to be moved, so I need to get it started when I get home. In the mean time, I want to think about the options I have.

Any ideas on charging the 300V hybrid pack?

Thanks

 

[swathdiver]

My 2008 HyHoe was running just find although I think the original 2008 hybrid battery was starting to go. I was not getting much distance running on just the battery... far shorter than usual. I parked it in the fall, I didn't disconnect the batteries expecting my wife to run the engine once a month to charge up everything. Well, she forgot..... 4 months later and after several periods of below zero weather, she went to start it.... its completely discharged. Not even the electric locks work, not even a dim dome light.

I'm not home yet - I'm still out of the country for another 2 months, still lots of winter left back at home, so I'm going to assume that the brand new $200+ AGM battery is now frozen and trashed. What about the NiMH hybrid batteries.... can they freeze and be damaged if they are discharged and then exposed to freezing temperatures? I'm assuming the hybrid battery pack will be discharged since from what I understand, the hybrid system maintains the charge on the 12v system. So if the 12V is dead, the 300V must be dead.... and frozen.

Lastly, I did a search in the forum but I didn't find an answer. Maybe I used the wrong search words.

Since the engine is started off the hybrid battery pack, is there a way to put a charge in the hybrid battery from a charger. I'm sure I could figure out something going the reverse engineering route taking the lid off the battery pack and build a 300V+ charger... but really before going that route, I'd like to see if there is a proper way, like what the dealer would do if a hybrid Tahoe came in with dead batteries. It would be a real stup!d design if the engine uses the hybrid battery pack, and the engine is the only way to charge the hybrid battery pack. There's gotta be a way of charging the hybrid pack to get the engine started.

I had plans to replace the hybrid pack.... now it looks like this spring/summer will be that job. But till I get to it, the Tahoe needs to be moved, so I need to get it started when I get home. In the mean time, I want to think about the options I have.

Any ideas on charging the 300V hybrid pack?

Thanks

@RebelBelle

Could your wife put a charger on the under the hood battery or put it on a tender to rejuvenate it?

 

[bbOOmm]

The 12V battery under the hood is not the problematic issue - it can be easily charged and/or replaced. Its the 300V hybrid battery under the rear passenger seat that I need to charge somehow. To start the engine, one of the 300V motors in the transmission spins to crank the engine - that motor is powered by the 300V hybrid battery. On the 6.0L LFA engine on the hybrid Tahoe's, there is no typical 12V starter motor like you find on typical gassers. The 12V system is for powering the logic, controls and lighting... nothing to do with cranking the engine other than powering the ECM and other electrical stuffz like ignition coils, sensors etc.

How can I charge the 300V hybrid battery so I can get the engine started? Once the engine is started, the electric motors in the transmission switch to generator mode and charge the 300V hybrid battery.... this is where the problem lies - the engine needs to run to charge, but the battery needs to be charged to start the engine. Unless there is another way of charging the 300V hybrid battery - that is what I'm asking.

 

[wjburken]

I believe you can jump the vehicle with a 12V battery even when the 300V battery is dead. There are instructions in the manual on how to do it.

https://my.gm.com/content/dam/gmown...2008_chevrolet_tahoe_hybrid_owners.pdf#page81. I believe it’s on page 5-16.

Here is another post from electricvehicleforums.com regarding this same thing.

 

[bbOOmm]

Well, I found this using Jump-Assist as a keyword... looks like I have to get a Tech 2 Scan tool to initiate the APM to charge the 300V pack from 12V.

Now, to find a Tech 2 Scan Tool that will work.... I'm very leery of the chinese knock offs that are flooding ebay and amazon .... or are they OK?

 

[swathdiver]

Well, I found this using Jump-Assist as a keyword... looks like I have to get a Tech 2 Scan tool to initiate the APM to charge the 300V pack from 12V.

Now, to find a Tech 2 Scan Tool that will work.... I'm very leery of the chinese knock offs that are flooding ebay and amazon .... or are they OK?

Vetronix and Bosch transferred production to China over a decade ago, the original factory still makes them, while one or two people have gotten duds, the rest of us have had excellent results and even good customer service. The key is to buy from a seller with genuine reviews and lots of sales.

Is the truck in Florida, there's a couple of us around the state on here who have them.

 

[bbOOmm]

Vetronix and Bosch transferred production to China over a decade ago, the original factory still makes them, while one or two people have gotten duds, the rest of us have had excellent results and even good customer service. The key is to buy from a seller with genuine reviews and lots of sales.

Is the truck in Florida, there's a couple of us around the state on here who have them.

No the vehicle is in Wisconsin.

I'm seeing some Tech 2's for $250, some in the $350 range, some over $450.... most are shipped from China. Just wondering, what is the new price for a Tech 2 scan tool.... I know scammers with fake items like to price things really cheap.... I don't want to fall for that.

 

[swathdiver]

No the vehicle is in Wisconsin.

I'm seeing some Tech 2's for $250, some in the $350 range, some over $450.... most are shipped from China. Just wondering, what is the new price for a Tech 2 scan tool.... I know scammers with fake items like to price things really cheap.... I don't want to fall for that.

They were over $3K. GM has moved on to other types of tools. The going rate for the Chicom ones is about $300-350 last time I looked. Could be less, just make sure it comes with all the little adapters, the CANdi module and VCI module and most importantly the 33.004 version software on the PCMCIA card.

Historically, they don't take long to get here. I ordered a new CANdi module for mine from them on January 20th, should have it tomorrow.

 

[BG1988]

No the vehicle is in Wisconsin.

I'm seeing some Tech 2's for $250, some in the $350 range, some over $450.... most are shipped from China. Just wondering, what is the new price for a Tech 2 scan tool.... I know scammers with fake items like to price things really cheap.... I don't want to fall for that.

the other choice would to manually charge each battery using a regulated controller ..


remote start button is an option just tap the lock twice and the start button.. and pressing the start button again will automatically shut it off

 

[bbOOmm]

the other choice would to manually charge each battery using a regulated controller ..


remote start button is an option just tap the lock twice and the start button.. and pressing the start button again will automatically shut it off

I would have no problem making an individual cell charger or making a 300V+ charger... if I had to go that route. I'm going to try the onboard Jump-Assist first. I just need to get a Tech 2.


I'm not sure I understand your remote start button comment --- I think 2x lock then start button is to remote start procedure, not to put the system into Jump-Assist.