Ongoing 12v battery problem

Faults and Technical chat for the Honda E
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Post by londiniumperson » Sat Oct 22, 2022 10:39 am

Onthecharge wrote:
Sat Oct 22, 2022 10:20 am
Dealer has contacted me this morning, Honda UK have said the problem is that if the new 12 volt battery in not fully charge when fitted and is in a semi discharged state the E will only recharge the 12 volt battery to the semi discharged state as fitted ( if that makes sense ? ) I am not convinced this is the cause ,we shall see !
I can see logic in that, but if that is the case, then many people in the Honda requirements, development & testing dropped the ball big time on this.
It's pretty obvious that any system should be designed to be independent of external factors where possible because this makes it quicker, easier & cheaper to integrate into the end product and re-use in others. It's the 101 of corporate company manufacture engineering.
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Post by Wee Peem » Sat Oct 22, 2022 12:22 pm

The dealer was talking a load of cobblers there. Just some words to get you out the door and off his hands I reckon.

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Post by Onthecharge » Sat Oct 22, 2022 2:28 pm

Like I said I'm not convinced with the explanation of the fully charged battery scenario , you can't get to talk to a technician. Service reception just read off the job sheet and give you the keys and offer coffee, time will tell if it's a permanent fix or get you out the door fix.

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Post by Onthecharge » Sun Oct 23, 2022 9:38 am

I picked the E up yesterday Saturday 22nd It looks like a brand new battery has been fitted ( I marked the fitted 3rd one ) The main battery was fully charged and my battery monitor refitted. Finger crossed this will cure the problem but I'm not holding my breath .

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Post by milligoon » Wed Oct 26, 2022 2:17 am

The cause is simple they are to small a capacity to hold charge for a long period given the nature of these cars never really being off.
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Post by Onthecharge » Wed Oct 26, 2022 8:20 am

Yes your right there's a lot of power needed to run the screens and cameras etc. but what I can't understand is why the software will not automatically charge the 12 volt battery from the main power pack when it starts to run low if the car is parked with an almost full charge in the traction battery.

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Post by Flatagain » Wed Oct 26, 2022 8:49 am

Please keep us updated as I’m seeing the same issue!!

I have a 2020 e with 7000 miles I bought from a local dealer last month. Day one it left me stranded after being driven a decent amount and then left for 10mins. The dealer mechanic drove out and got it running and it went back for ‘checking’ but no issues apparently.

Since then it went back last week with same flat 12v even though I use the car every day so it’s not left to go flat. Now it’s flat again this morning after parking up at 7pm the night before.

I could understand if the car was left and not used but I’m using the car daily and being super careful to ensure I turn it off completely and don’t accidentally leave any lights on etc as that is what I’m being told is the issue.

Interestingly I told the dealer I would be sending it back every single time this happened until something is done and when I asked if any other owners were having issues they admitted there were others. I know all BEV’s can suffer similar issues but it just seems the Honda e issues are worse as the car will be unusable for me if this continues. Has anyone heard anything official from Honda about a fix??

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Post by EEEE » Wed Oct 26, 2022 10:58 am

How long are you driving it for each day out of interest?

It's a shame there isn't much more room in the battery tray for something bigger than 45ah.
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Post by Onthecharge » Wed Oct 26, 2022 11:06 am

No short journeys 45/ 50 miles in one go, so around 90/100 miles out and back, + parked up for anything up to 4/5 hours then on to overnight charge on Hypervolt charger at home.

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Post by Flatagain » Wed Oct 26, 2022 11:15 am

I use it on 20min run minimum. It’s usually run for at least 30mins per day.

I’m convinced there is something quirky with the 12v charging system on the car. There were a few posts mentioning that the main traction battery will not charge the 12v if it’s above 90% state of charge. It would be interesting to see if anyone had a definitive answer on this.

I’m currently taking manual readings of the 12v with a multimeter to see how quickly it’s being drained. It’s also interesting that the Honda e doesn’t appear to have the ability to display battery voltage? Surely the system should monitor this and then provide charge from the traction battery if it drops too low.

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