Dead Honda e

[5thcivic]

I misunderstood it never moved, that must be weak then, maybe a cell has gone?
My charging typically takes about 3 hours (5A) with one and 4/5 hours (4A) with the other to full, the chargers also have slightly different current/pulse graphs.

[ZeroEmissionRequiem]

I misunderstood it never moved, that must be weak then, maybe a cell has gone?
My charging typically takes about 3 hours (5A) with one and 4/5 hours (4A) with the other to full, the chargers also have slightly different current/pulse graphs.

Well that's what I expected, yet as I wrote, it passed the dealerships battery test with flying colours. Something has to be off; battery dies and is at 3 volts, revival attempts with the Defa SmartCharge fail yet it achieves 12.62 V and "475 A" on the test despite being labelled a "400 A" (CCA?) battery. I guess I'll get another battery test done, elsewhere...

[MaXPainT]

All this talk has scared me into buying a lithium jump starter despite never having an issue with my battery so far. Better safe than sorry A youtube channel Project farm has recently convinced me that Noco GX45 is a good starter. Probably, an overkill for the E, but one never knows where one might find themselves. Winter is coming.

Out of curiosity, has anyone experienced a dead 12v battery with the car being plugged in?

[ZeroEmissionRequiem]

Out of curiosity, has anyone experienced a dead 12v battery with the car being plugged in?

Yes. The HV battery was at 100% when the car was revived with a starter.

Now that I look at my data, I can see a fairly obvious pattern here; during this month there was only one day on which I didn't drive the car at all, and on the next day I found it dead:

I'll have to let it sit unused some day and see if the problem reappears.

[EEEE]

The 12v battery is not always charged whilst plugged in.

My observations (and that of others) are that the battery is applied with 13.3v ONLY whilst AC charging takes place. If you charge from 80% to 100% of the HV overnight, even if its plugged in and AC powered for 12hours, it will only take an hour to charge the HV batt, so the 12v batt is only charged for that same 1 hour also. The remaining 11hours you left it plugged in do nothing.

If you leave it plugged in for 3 days continuously powered, it will only charge for that single 1hour period in the whole 3 days.

13.3v is not enough to really charge it especially only for a short period.

My observations also show that actually, whilst the mains power is applied, if the HV battery doesn't need charging because its at 100%, because various systems must power up, coolant pumps run etc, the voltage dips a little and the 12v battery is actually depleted a little bit.

Hopefully my battery capacity discharge tester turns up today, and I can compare the Panasonic OEM battery against the similarly sized Yuasa new one and see if the few occasions it went flat have actually reduced its capacity much.

[ZeroEmissionRequiem]

Yeah, I'm aware it apparently only charges some of the time.

Had a 3rd party battery test done now; 12.86V & 394 A, voltage with the car powered up was 14.64 V. As such, the battery does seem fine now. Perhaps the 3 V reading the road service guy got when it was dead was false, though I saw it with my own eyes as well...

[EEEE]

Was the test performed with the battery still connected to the vehicle?

Perhaps the batteries that have depleted are a little more resilient than we had expected...

[MaXPainT]

Does it matter how fast the AC charging is or any AC charging applies the 13.3v? There are charges with variable amperage, so, technically, it is possible to greatly slow down the charging process and it would take way longer than an hour for the HV to get from 80% to 100%. Maybe, with such a charger, it would be possible to trigger some sort of preservation mode where the HV is charged slowly keeping the 12v topped up? I don't think that it would be necessary to constantly reduce the amperage, but doing it like once in a couple of weeks to boost the 12v should do it. Or am I missing something here?

[EEEE]

I suspect if you charged up with the granny charger, the 13.3v 'charge' would be held for longer. Technically, 13.3v is not a real charge, more of a float to be held after the battery is bulk charged. I haven't found much documentation about what happens if you hold a semi-flat battery at float voltage without first having been fully bulk charged.

It may well be that holding a semi-charged battery at 13.3v is actually what is slowly killing them off...

I will test this this weekend, I will set my hypervolt 7kw charger to its lowest setting (I think just over 1kw) and leave it on charge and check the following day.

[ZeroEmissionRequiem]

Was the test performed with the battery still connected to the vehicle?

Perhaps the batteries that have depleted are a little more resilient than we had expected...

Yeah, both tests were with the battery connected. Should I have questioned this?

Well well...I found my old multimeter, and decided to check the battery voltage myself. I connected it to the battery terminals and ran the cables to the charge port so that I could close the bonnet and thus lock the car properly.

When I unlocked the car and opened the driver's door, headlights turned on, and the voltage semi-slowly dropped down to 12.07 V.

When I powered it on, to ready to drive state, voltage stayed at 14.74 V.

I then shut the car down and locked it, took the key a suitable distance away to keep the car from reacting to it, and the voltage dropped to around 12.50 V or so. It started climbing, however, and 10 minutes later it was at 12.72 V and appeared to stay there.

I then went to the key, started preconditioning, and walked back to the car (still keyless). Voltage was now at 13.62 V, indicating that the 12 V battery is being charged during preconditioning.

After stopping preconditioning, I connected my Defa SmartCharge charger to the 12 V battery, and observed the multimeter. The charger started at 1/5 bars with another bar blinking, as it did before, at around 12.50 V. However, over a few hours the voltage kept steadily climbing along with more bars becoming lit, all the way up to 14.80 V at 4/5 bars with the 5th blinking. By morning, the charger indicated 5/5 and voltage held at 14.08 V. I turned off the charger, and the voltage dropped to 13.24 V. About 7 hours later it was still 13.12 V! Sure doesn't seem like a battery that's on its death throes.

Even more weirdly, something good appears to have happened to the battery/car during my visit to the dealership, even though they said they only checked the fault codes and ran a battery test (with their Honda-branded Midtronic EXP-1030). Thing is, as I've written, after the battery death the Defa charger couldn't charge the battery even overnight, still indicating 1/5 bars. Also, the only problem I noticed with the car after said incident was with the steering wheel heater; it would warm up as normal, but cool down soon after until it was cool to touch, despite the light staying on. However, after the dealership visit, the battery is accepting charge from the Defa charger, and the steering wheel heater is back to normal as well. Hell, it seems the ambient temperature sensor misbehavior has stopped, too! I'm also now getting a "it's cold, charger connection recommended" message upon parking, which I don't think I've seen before.

EDIT: Ambient temperature sensor is still being weird.