When the 12Vdc battery dies...

[NKemp]

I just wanted to post should others experience the same.

I drove 30+miles into town, and moved the truck a short distance a couple times. I was parked outside an apartment and as such, I put the 4-way flashers on. Nothing unusual. When I went to leave, the truck was almost TOTALLY DEAD. DIC worked but no clicks, moans ar anything. Even the windows were hesitant at best. Had to manually lock the doors. The only clue I had was that DIC said the 12Vdc battery was at 9Vdc.

I called for a tow truck and he tried jumping with the portable pack and then via the truck jump batteries (2x12Vdc). Nothing.

The dealer just called and said it was the 12Vdc battery. A bad cell. Evidently, when the 12Vdc battery drops low enough, the truck will not start. The strange part is that the jump did not give it enough to start. This may be somewhat unique to the hybrid.

Moral of the story is if the battery is low and it won't start, a battery replacement may do the job even if a jump will not.

 

[NKemp]

I talked with a mechanic at the dealer and his thought was that the truck would have started had the battery been disconnected and the jumpers connected directly to positive and negative vehicle points. But we didn't discuss what would happen after the jump. What would happen if the battery was reconnected? Can you drive without the 12Vdc?

If you rely on this vehicle then it may be advisable to keep a 2nd 12Vdc battery onboard. Could be set up as isolated batteries. Maybe the 2nd need be no more than a motorcycle battery. Then you'd need tools to disconnect the failed battery.

I mention all this because of how stranded I was due to a failed 12Vdc cell. I've had other vehicles with bad batteries that a jump would get going. The jump to this vehicle produced no change... it was still not going to start.

 

[ccapehartusarmyINF.(ret)]

since most diesel trucks are a 24 volt system especially a tow truck if you disconnected your battery and tried to jump yer car off that tow trucks 24 volt system wow that would have been bad

 

[NKemp]

They were 2 12Vdc batteries in parallel, not series so it delivered 12VDC with lots of amp capacity. He was a professional towing service and new my battery was 12Vdc. So the discussion was around applying a 12Vdc jump not a 24Vdc jump. But your point is well taken...24Vdc into a 12Vdc system would not turn the starter twice as fast... at least not for long

 

[ccapehartusarmyINF.(ret)]

you dont need to use "vdc" you can just say 12v or 12 volts the DC is for direct current and everything on a vehicle is direct current
yeah i actually just read about jumpstart system that companys are putting on there tow trucks and other service vehicles that either puts out 24 or 12 volt
batteries wired in parallel the voltage remains constant but the amp/h increases

 

[NKemp]

you dont need to use "vdc" you can just say 12v or 12 volts

Yes .. that is a habit of mine. I write about a variety of voltages in dc and ac. For example
- 24V when used in the automotive/aviation world is dc and in residential and commercial HVAC it is ac.
- 300V to us may imply the dc traction batteries but if you heard that mentioned by an electrician, he may be talking about 277Vac commercial circuits (usually lighting) depending on how well the power company is holding to spec voltage.
- If a laptop power port takes 12V to charge, it is likely 12Vac and using the car's 12Vdc could be problematic. But this is a case where checking the label is important.

When I had tech writers, we always capitalized the "V" since it was a name (named after the Italian physicist Alessandro Volta). But I digress.

So to be clear I use the full qualifier such as 24Vac out of habit and I'd argue that clarity is always worthwhile, especially around voltages.

Clarity can be very important. The following two statements have substantially different meanings
- Let's eat, grandma
- Let's eat grandma