Ongoing 12v battery problem

Faults and Technical chat for the Honda E
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EEEE
Posts: 569
Joined: Mon Aug 16, 2021 10:33 am

Post by EEEE »

I think the 12v charging system is witchcraft, works when it wants to, and not terribly well when it does. As said, the battery is so small, it can go flat so easily and never recover properly after the fact.

Strangely, i've had mine since August last year , and previously been in use all the time since April 2021 and ive never had a single 12v problem at all. It has some short journeys, but mainly 30min commute twice a day, 5 days a week.

I never sit in the car with just the ignition on so as to drain the 12v battery, if i am sitting in the car, I just put it in park/handbrake and leave the whole thing on. the 45ah battery can throw the low power warning in a matter of minutes otherwise.

I had contemplated a lithium 12v battery replacement, but they don't seem a huge capacity boost for the size, and who knows how well the built in 12v charging system would handle it.

I Still keep a lithium 12v power jumper in the glovebox just incase however.
'21 e Advance - Charge Yellow - E1702RR alloys
'17 Civic Sport CVT
'00 Prelude 2.2VTi

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keithr
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Joined: Fri Feb 07, 2020 1:30 pm
Location: Dorset, UK

Post by keithr »

Just to share my expeience, I've had my car for just over two years (since September 2020) and the 12v battery is still okay (so far!). As I've retired I don't have a daily commute, and I've only covered just over 4,000 miles in those two years. Typically I would use the car a minimum of 4 times a week and most of those trips are only about 2 miles out, then 1 - 2 hours later 2 miles back (I do more trips, and longer trips, in the summer months). So as preventative maintenance I've always put the 12V battery on charge once a week. I use a 5 amp CTEK smart charger, and it typically can take around 5 hours to bring the 12V battery back to full charge (it didn't take that long when the car/battery was new - it would charge in less than an hour then), so I guess the 12V battery is probably only around 50% charged after a week of (not much) use. Perhaps I should charge it more than once a week, but I'll continue with just once a week and see how long the battery lasts.
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FDAD
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Post by FDAD »

keithr wrote: Wed Oct 26, 2022 2:04 pm Just to share my expeience, I've had my car for just over two years (since September 2020) and the 12v battery is still okay (so far!). As I've retired I don't have a daily commute, and I've only covered just over 4,000 miles in those two years. Typically I would use the car a minimum of 4 times a week and most of those trips are only about 2 miles out, then 1 - 2 hours later 2 miles back (I do more trips, and longer trips, in the summer months). So as preventative maintenance I've always put the 12V battery on charge once a week. I use a 5 amp CTEK smart charger, and it typically can take around 5 hours to bring the 12V battery back to full charge (it didn't take that long when the car/battery was new - it would charge in less than an hour then), so I guess the 12V battery is probably only around 50% charged after a week of (not much) use. Perhaps I should charge it more than once a week, but I'll continue with just once a week and see how long the battery lasts.
I've never had a single problem with the 12v battery since I got the car august 2020 still with the original battery.
Honda E advance [Modern Steel Metallic] 8-) [DELIVERED JULY 2020] - 85 000Kms + ✌️🎂
mattchr
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Joined: Mon Apr 17, 2023 1:33 pm

Post by mattchr »

After owning our Honda E for 18 months, the 12v battery was completely goosed and beyond recovery. Needed a jump start, as soon as the off button pressed all 12v systems died including central locking! This was with using a 12v battery maintenance charger, trying to leave HV plugged in etc etc. typically dying in less than a week while on holiday.

Honda released a Battery Control Module (?) software update, which the dealer installed and should alleviate some of the charge and discharge behaviours. We’ve also received a replacement 12v under warranty.
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keithr
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Location: Dorset, UK

Post by keithr »

mattchr wrote: Mon Apr 17, 2023 1:41 pm This was with using a 12v battery maintenance charger, trying to leave HV plugged in etc etc. typically dying in less than a week while on holiday.
If the charge cable is left plugged in then it will only trickle charge the 12V battery (at 13.3V, or 13.6V if the A/C preconditioning is on) if the car is charging or the battery heater is on. So if it's not so cold that the battery heater is on, and once the HV battery has reached its target SOC, then it will then not charge the 12V battery at all. Therefore leaving the cable plugged in will probably not help much.

The car will charge the 12V battery at 14.6V while the car is turned on and the SOC of the HV battery is less than 90%.
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londiniumperson
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Joined: Fri Oct 11, 2019 2:37 pm

Post by londiniumperson »

mattchr wrote: Mon Apr 17, 2023 1:41 pm After owning our Honda E for 18 months, the 12v battery was completely goosed and beyond recovery. Needed a jump start, as soon as the off button pressed all 12v systems died including central locking! This was with using a 12v battery maintenance charger, trying to leave HV plugged in etc etc. typically dying in less than a week while on holiday.

Honda released a Battery Control Module (?) software update, which the dealer installed and should alleviate some of the charge and discharge behaviours. We’ve also received a replacement 12v under warranty.
It hasn’t fixed anything as far as I’ve noticed because I left the doors open on my car whilst I cleaned it this weekend and didn’t turn the car fully on or completely off.
Guess what? The 12V battery was completely dead. An a hour or so of being on charge was enough to enable me to power on the car.
2020 Advance in Crystal Black Pearl on 17's - 08/2020-Current
2015 VW Tiguan (Pure White) - 04/2018-Current
1991 Honda Beat PP1 (Festival Red) - 11/2022-Current
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EEEE
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Joined: Mon Aug 16, 2021 10:33 am

Post by EEEE »

I've given up trying to work out how this car works. A new scenario occurred yesterday for example that hadn't happened before.

Arrive at a rapid charging station. Plug in and start charging. Wife turned off the car. We sat in the car, car auto locked. Because it was turned off (I think), the car locked itself and set the alarm despite not pressing the lock button on the fob. As soon as I reached into a bag for some Jaffa cakes, the movement set the bloody alarm went off with us in the car. I must have eaten a thousand Jaffa cakes or equivalent whilst charging and never had the car arm itself with me in it. Not sure what was different about that time to countless others. Happened twice in short succession until I turned the car on fully to stop it happening again.

Likewise, left the car parked up for 2 weeks at the in laws, in a garage, 12v battery didn't go flat despite a fairly low state of charge in the HV battery. Was fully expecting it to go flat like before (so much so, I left the bonnet popped open to allow easy jumpstarting.
'21 e Advance - Charge Yellow - E1702RR alloys
'17 Civic Sport CVT
'00 Prelude 2.2VTi
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Reuben80
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Location: Malta

Post by Reuben80 »

EEEE wrote: Mon Apr 17, 2023 3:52 pm I've given up trying to work out how this car works. A new scenario occurred yesterday for example that hadn't happened before.

Arrive at a rapid charging station. Plug in and start charging. Wife turned off the car. We sat in the car, car auto locked. Because it was turned off (I think), the car locked itself and set the alarm despite not pressing the lock button on the fob. As soon as I reached into a bag for some Jaffa cakes, the movement set the bloody alarm went off with us in the car. I must have eaten a thousand Jaffa cakes or equivalent whilst charging and never had the car arm itself with me in it. Not sure what was different about that time to countless others. Happened twice in short succession until I turned the car on fully to stop it happening again.

Likewise, left the car parked up for 2 weeks at the in laws, in a garage, 12v battery didn't go flat despite a fairly low state of charge in the HV battery. Was fully expecting it to go flat like before (so much so, I left the bonnet popped open to allow easy jumpstarting.
When you say the car auto locked I think you mean the handles went back in but the car did not actually lock.
We need to see when the alarm arms itself, if after full lock or not.
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