Ongoing 12v battery problem

Faults and Technical chat for the Honda E
Onthecharge
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Joined: Sun Aug 15, 2021 7:51 pm

Post by Onthecharge » Sat Oct 15, 2022 8:31 pm

The E is back in the dealership at 14000 miles 12 volt battery has discharged to 9 volts after leaving it parked for a couple of hours. According to the battery monitor it happens as I approach the car ? Handles don't flip out have to unlock the car with the button on key. Dealer has had it for 2 x days and its happened twice while with them, spoke to them today much head scratching going on, Have there E demo car on loan until Monday.

Onthecharge
Posts: 26
Joined: Sun Aug 15, 2021 7:51 pm

Post by Onthecharge » Mon Oct 17, 2022 6:47 pm

Dealer called me today with update to say no progress yet as to cause of problem and have contacted Honda for advice.

Onthecharge
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Post by Onthecharge » Wed Oct 19, 2022 2:23 pm

Honda have supplied a new 12 volt battery to be fitted today, this will be the 4th battery that has been fitted, I am not convinced this is the solution to the problem ! Watch this space.

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EEEE
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Post by EEEE » Wed Oct 19, 2022 3:14 pm

If the key is within range - this does tend to wake the car up. I make a habit of putting mine towards the back of the house and not going near the car.
'21 e Advance - Charge Yellow - E1702RR alloys
'17 Civic Sport CVT
'00 Prelude 2.2VTi

Onthecharge
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Post by Onthecharge » Wed Oct 19, 2022 7:40 pm

The battery will go flat after walking away from the the car and coming back 2 to 3 hours later its been an ongoing problem since owning it Honda rescue ( the AA ) have been called out about 9 or 10 times the verdict is that something has been left on But I assume when you lock the car and walk away it shuts everything down. I always check radio off lights off lock car and walk away.It has also happened when parked on the drive at home after overnight charging, no key or mobile phone within 10 mt of the car. According to the battery monitor it just drops down to 9 volts

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FDAD
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Location: Porto, Portugal

Post by FDAD » Wed Oct 19, 2022 8:03 pm

Onthecharge wrote:
Wed Oct 19, 2022 7:40 pm
The battery will go flat after walking away from the the car and coming back 2 to 3 hours later its been an ongoing problem since owning it Honda rescue ( the AA ) have been called out about 9 or 10 times the verdict is that something has been left on But I assume when you lock the car and walk away it shuts everything down. I always check radio off lights off lock car and walk away.It has also happened when parked on the drive at home after overnight charging, no key or mobile phone within 10 mt of the car. According to the battery monitor it just drops down to 9 volts
You must have a parasitic draw somewhere...
Honda E advance [Modern Steel Metallic] 8-) [DELIVERED JULY 2020] - 50 000Kms + ✌️🎂

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londiniumperson
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Post by londiniumperson » Wed Oct 19, 2022 10:18 pm

FDAD wrote:
Wed Oct 19, 2022 8:03 pm
Onthecharge wrote:
Wed Oct 19, 2022 7:40 pm
The battery will go flat after walking away from the the car and coming back 2 to 3 hours later its been an ongoing problem since owning it Honda rescue ( the AA ) have been called out about 9 or 10 times the verdict is that something has been left on But I assume when you lock the car and walk away it shuts everything down. I always check radio off lights off lock car and walk away.It has also happened when parked on the drive at home after overnight charging, no key or mobile phone within 10 mt of the car. According to the battery monitor it just drops down to 9 volts
You must have a parasitic draw somewhere...
Has the battery monitor been connected to any of the other 12v batteries?
2022 Advance in Crystal Black Pearl on 17's - 08/2022-Current
2015 VW Tiguan (Pure White) - 04/2018-Current
2001 Toyota MR2 (Liquid Silver) - 06/2022-Current
1991 Honda Beat PP1 (Festival Red) - 11/2022-Current

Onthecharge
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Post by Onthecharge » Wed Oct 19, 2022 10:39 pm

No it has just been connected to this battery , the third one, is it relevant ?

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londiniumperson
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Post by londiniumperson » Thu Oct 20, 2022 11:51 am

Onthecharge wrote:
Wed Oct 19, 2022 10:39 pm
No it has just been connected to this battery , the third one, is it relevant ?
If it had been on 3 of the 4 then I would be considering that it was the cause of the parasitic draw.
Either way I’d consider disconnecting it for at least a few weeks to be doubly sure.

Do you have a dashcam or anything else connected to the 12v, if so then look at disconnecting those as well, from my experience you can’t rely on a garage whether main dealer or independent to do anything correctly these days.

Only last year I had a cambelt changed by what was supposedly the most respected independant garage in my local town but I had to take it back 3 times because the coolant level kept dropping. I can understand that this could require a top once but my beef was with the fact that they obviously hadn’t bled the system and at the 2nd top up they said that it’s most likely to be an issue with a water heated manifold and would be expensive to repair and would not even consider that it was an error on their behalf. It’s been fine since so obviously they employ incompetent mechanics.
We’d had the var 4 years at that point and I check the levels monthly so knew it wasn’t an issue before they worked on the car, but they thought I lied when I told them this.
2022 Advance in Crystal Black Pearl on 17's - 08/2022-Current
2015 VW Tiguan (Pure White) - 04/2018-Current
2001 Toyota MR2 (Liquid Silver) - 06/2022-Current
1991 Honda Beat PP1 (Festival Red) - 11/2022-Current

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EEEE
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Post by EEEE » Thu Oct 20, 2022 3:04 pm

It's unlikely that a battery monitor would draw that much current.

If the 12v battery is definitely full, and definitely depleted in 2 or 3 hours, then we are talking about a 10 or 15amp draw continuous.

The only way to get to the bottom of these things is sadly to do it yourself. You can buy blade fuse plugin leads for multimeters, and at least narrow down which circuit/circuits are drawing current when the car is turned off. Bit of a faff to go through every fuse but you will learn a lot in the process.

I would also try a full software reset of the infotainment - it's so glitchy and bad it wouldn't surprise me if a software bug is to blame for not going to sleep when it should.
'21 e Advance - Charge Yellow - E1702RR alloys
'17 Civic Sport CVT
'00 Prelude 2.2VTi

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