My 12V reading is all over the place. Sometimes 15V sometimes 13V. As long as it is over 11V and under 17V, I'm happy...

 

so, you have seen 16V? has any one else seen 16V, the highst I have seen it is 15V and the only time i could see 12V is when the ignition is off.

 

No, I don't think I've seen 16V, but I wouldn't stress over it if I did.

 

Hi guys. The highest you should ever see is 15. (14.5 to 15.4 rounded) If you see 10 you probably won't get it to start up. It is completely normal to see 14 to 15 right after start up. After a few minutes with headlights off, wipers off, and air conditioning/heat blowers low, it should rampdown to 13.

The voltage while driving will varry with HVAC, headlights, and wipers.

You need more than 12.8 (13) to keep bright lights, fast wipers, and high HVAC blowers.

So a sunny day at 20C just me and the radio windows down I ramp down to 13 within 2 miles of my driveway on the way to work.

Omar: if you key to run without starting, what voltage do you usually get? Also abserve what exterior lighting and gadget settings are. Most of these loaded vehicles turn on everything at key to run.

If all the gadgets pull you down to 10, you most likely won't crank.

 

I'm still getting 12V when key without starting at factory settings (everything is on). I start to believe my issue is more related to the wrong signal the modular is getting from the faulty transmission harness. I'm sharing similar volt reading on the rest of the scenarios.

 

I re-read these posts and just wondering here if there is a misunderstanding of what you should be reading. I don't know how the 2 mode hybrid is set up vs. a standard engine/alternator/battery package but it is still somewhat similar.

With nothing powered, if you checked battery voltage at the battery it would be around 12.5volts. Now if you read that on your volts gauge in the truck, you have to turn the key to the acc position to see it but you are now powering some accessories in the truck, so you may see slightly lower but still in the 12-12.5 range. Hillbilly_Hybrid, Marty, you may have to answer this, but when the key is in the run postition but the engine has not been started, does the Drive Battery supply any charge through the regulator to the 12volt battery? If it does, even with the engine not running you may see something higher than 12.5volts. But regardless, you will see battery voltage only until it has a charge on it then you will see the charge voltage...until it drops back down in the fully charged range, then you will see the amount of charge that it takes to keep the battery topped plus the amount of voltage you are drawing. Very similar to a standard engine/battery/alternator combination which would read very similar to this as well.

Just a thought here on the original issue. If you place the key in RUN and DO NOT START the engine, the accessories will be powered and you will drain the battery below what is capable to start it. The manual says to start the engine if you sit for extended periods to prevent this.

 

Does the 12 V battery gets its power /or gets charged from 300V battery, or from Engine Alterntor?

Tanks

 

Guss,
The Hybrid has no alternator at all neither any other component attached by belts except the water bump (Like an Amtrak engine. free standing engine with no belts attached). the hybrid modular keep the charge in the 12V battery from the 300V.

 

I just got back from a trip to the dead sea. I didn't catch any fish's (wondering Why!) but the ride and the resort was awesome.

 

Thanks Omar,
I should be receiving my tahoe next week if all goes well
How is your Yukon treating you?