Explain to me how my batteries work please?

[Miss415]

I am wanting to understand how the 2 batteries work together- the one under my hood and the huge one in back. 

I have the 2013 Energi and had the battery replaced under warranty about a year ago after car kept going completely dead.  No problems until this past week.

The issues I had previously, my radio would stop turning on and 2 days later, my battery was dead even though I had been charging it every night. So fast forward.. .  no issues since battery replacement until a few days ago, my radio would not come on. Car was on charger all night. 2 days later,

I came home & needed to charge car as battery at 0%.  I couldn't plug it in it right away and ended up leaving it overnight. Next day, car was dead.  I jumped it & thought it would be fine but when I got back into my car after disconnecting the jumper cables & parking the other car I used to jump, it was off & dead again & would not start. Ugh! So is that normal?

I ended up charging it again same way and left it for 30 minutes and it started & I was able to pull into my driveway where my charger is & plug it in.  Started up fine this morning. I'm mainly just wondering if that's normal or not. A family member has the same car/ year and purchased a portable charger she keeps with her. I just purchased one for myself last night! 

Hoping was happened was my own fault! Thanks in advance!

[plus 3 golfer]

First, there is no 12 V battery under the hood.  The 12 V battery is located under the floor in the hatch area.  The big High Voltage Battery is also in the back.  Which battery did you have replaced under warranty? 

To start your car,  the 12 V battery needs to be able to power up all the control modules in the car.  The control modules then run checks to insure your car is “ready to drive” which primarily means that the HVB is properly connected to the High voltage system and the control modules are functioning.   Your car will not start if the HVB is not properly connected.

 

When your HVB is plugged in and charging from wall power, the 12 V battery is also being charged by a separate 12 V charger only used when car is plugged in and charging.   When the car in in “ready to drive” mode (HVB is connected), the 12 V battery is charged from the HVB by a DCDC converter module (there is no alternator like a conventional car). When car is off, the HVB is not connected to the HV system.

 

It sounds that you have a significant 12 V battery drain causing the 12V battery to completely discharge  in a few days.  The APIM behind the radio / display has been know to  cause battery drain.  You can try pulling fuse 79 in the fuse panel located under the glove box and leaving it out over night and see If battery drain stops.  Put it back in when you plan on driving car. 
 

Here’s a document you can read and learn a lot about the hybrid / Energi.

 

OBDSM1700_HEV.pdf

 

 

[Bill-N]

18 hours ago, Miss415 said:

I am wanting to understand how the 2 batteries work together- the one under my hood and the huge one in back. 

I have the 2013 Energi and had the battery replaced under warranty about a year ago after car kept going completely dead.  No problems until this past week.

The issues I had previously, my radio would stop turning on and 2 days later, my battery was dead even though I had been charging it every night. So fast forward.. .  no issues since battery replacement until a few days ago, my radio would not come on. Car was on charger all night. 2 days later,

 

 

Assuming it was the 12V battery that was replaced, your issue may well be caused by the battery-age-reset-procedure not having been done.  Your car needs to be told when the 12V battery is replaced in order to keep the new battery charged properly.  So if the battery age wasn't reset, you will likely need another new 12V battery (and the battery age reset at that time).

 

Search the forum for more info.

 

 

Cheers.