Posts: 4
Joined: Sat Aug 03, 2019 8:19 am

Info about 12V battery failure

Mon Aug 05, 2019 8:43 am

My 12V battery which runs the electronics has failed twice now, Honda replaced it both times. What I eventually found out is that this battery does not charge when the car is plugged in. It only charges when the car is driven. I have had several surgeries in the past 1.5 years and the car was always undriveable when I got home from recovery. I had it towed to the dealership twice but all it really needed was a jump start and to be driven. I bought a very small jump start battery thingy from Amazon for about $70 and keep it in the back for that possible emergency. It is so sad that this great car will likely never go into production. I would buy one in a minute.

Posts: 4
Joined: Sat Aug 03, 2019 8:19 am

Re: Info about 12V battery failure

Wed Dec 04, 2019 9:54 pm

Still no replies but I was wondering if anyone has had problems with the small battery that runs the electronics not charging. It is separate from the main large batteries and does not charge when plugged into the wall. It has been back to Hon da four times and they say nothing is wrong with it. They put a new battery in one year ago. Last weekend we drove it about 50 miles, drove it around town and drove it around the block before my doctor's appointment today and it was completely dead when we went to leave so had to borrow a neighbor's car. I love the car but this is extremely frustrating. Any ideas?

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Posts: 577
Joined: Fri May 31, 2013 12:42 pm
Location: Albany, NY

Re: Info about 12V battery failure

Tue Dec 24, 2019 2:51 pm

I think we covered it nicely for you in the Fit EV Facebook group. There is much more action there than here eh? ;)


Posts: 2
Joined: Sun May 17, 2020 8:18 am

Re: Info about 12V battery failure

Sun May 17, 2020 9:47 am

Did the $70 Amazon charger go dead as well??

Lead-acid car batteries are reliable only for 3 months or so if left uncharged. Best to bring them in the house and hooked to
a tiny 'float charger' to keep them fully charged. But you need to connect it back to the EV periodically to fire up the system and
check that the high voltage traction battery is still charged enough, like 50 - 70%. EVs are known to respond in differing ways to
having their 12 volt batteries disconnected which might cause the traction battery to discharge. To test your EV you could simply
disconnect the 12v negative for a few days then re-connect and see if the hv battery is still at the same mileage. Then try this for
longer periods until you gain confidence. EVs driven only short distances are likely under-charging their 12v battery. It
should suffice to drive for an hour each outing to fully charge the 12v battery. If you are sitting inside the car you can leave the
car ON which will continue the charging process.


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