Flat battery on a new car with Yuasa battery

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MrM83
Posts: 62
Joined: Fri Dec 08, 2023 10:19 am

Post by MrM83 »

Battery issues widely lamented on here.

I’ve had my car for about 3 months. Installed a Yuasa battery as soon as I got it. Came out today to find it completely dead which I must admit surprised me.

Scratching my head as to why. Last time I drove it was a week ago. My wife opened it yesterday to take a child’s seat out and seemingly no issue then. Wondering if she didn’t lock it and that caused some kind of problem. Either way I’m a little disappointed as I thought the Yuasa 053 battery would solve my problems on this front but evidently not.

Any ideas at all? Pretty sure I’ve left my car for a week without driving before so it doesn’t seem like I’ve left it for too long. No update pending, no update recently installed. I do have front and rear dashcams connected to a Garmin Constant Power OBD supply and set to record for 24hrs post ignition turn off, but it wouldn’t have been on for 6 days…

green1
Posts: 67
Joined: Tue Mar 26, 2024 1:18 am

Post by green1 »

Doubt it’s the battery, doubt it’s the Garmin, even if it was on for the whole week. So could be almost anything else causing parasitic drain. What was the HV battery % left at that week? Do either of you turn the car off with the start/stop button if you know the car is not going to be driven for a while - I don’t actually know if that makes a difference 😄 but it’s what I do. The car should auto lock anyway and unless the car was turned on by the fob to take out the seat that shouldn’t have used any power.

Maybe put a Bluetooth monitor on the battery after you charge it back up and keep an eye on it to see if drain aligns with any particular events next time you’re leaving it for a while.
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EEEE
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Post by EEEE »

Did you install the BM2? It's the only way to know when something started happening.

Don't discount the garmin, 45ah doesn't get you very far if something has been on for 24hr.

When the car was last opened/closed , was the car moved at all, or the drivers door left open perhaps? If you wake the car up (get in, but don't drive) and leave the drivers door open, the car will flatten itself quite quickly. Not sure about other doors.

The Yuasa battery doesn't fix the issue, it just replaces a crap battery with a decent one, but of the same capacity. I went larger because I was shocked just how easy it is to get the car to flatten itself. I fully expect it to be flat again sometime in the future (until we can work out what is happening).

My wife is borrowing the car on Friday, I await the phone call (again).
'21 e Advance - Charge Yellow - E1702RR alloys
'17 Civic Sport CVT
'00 Prelude 2.2VTi
green1
Posts: 67
Joined: Tue Mar 26, 2024 1:18 am

Post by green1 »

I also misread, both dashcams are actually on for 24 hours instead of park/sentry mode, not sure about the power draw from that but not immaterial. I definitely think turning the car off with the button is a good idea, it'll prevent the fob from waking the car if you're opening the doors to put stuff in or out, and the door open/sudden death type of failure does seem to be them most common on here.
MrM83
Posts: 62
Joined: Fri Dec 08, 2023 10:19 am

Post by MrM83 »

I’ve turned off as many auto things as I can. I turn the car on and off with the button. Unlock it with the fob. Car had 50% HV battery charge when last used when I came back from Heathrow. I haven’t been in the car. My wife opened it to take a child seat out to put in another car and locked it. That was yesterday. Flat today. The only other thing is I have a usb stick plugged into the right hand side, with audiobooks on. I’m aware you can do updates via usb, on off chance the car is trying to do something there.

I don’t have a BM2. I’ve seen reference to them but I’d be lying if I knew what one was. I’ll take a look at that, thanks.
MrM83
Posts: 62
Joined: Fri Dec 08, 2023 10:19 am

Post by MrM83 »

BM2 purchased. In fact I bought two, one for the e and one for my XC90.

Today I parked my car at the train station and came back to it 12 hours later having left the Garmin Constant OBD dongle on 24hr recording mode for the dash cam. Interestingly but perhaps unsurprisingly the battery voltage dropped steadily all day from near 100% state of charge to 19% and reading 12.20v. I’m guessing this is where my prior problem came from.

I will keep monitoring it, but onwards and upwards!

A couple of other observations; the battery recharges very quickly when driving around. Within 20 mins or so it was showing fully charged. It also got charged when I charged the HV battery.
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EEEE
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Post by EEEE »

Beware that the 'SOC' readouts from such monitors are poor indicators of state of charge. With lithium ion batteries, the charging is very efficient and the resultant voltage is immediately a very good indicator of SOC. The BM2 will only measure voltage.

With a 12v lead acid battery, the voltage is not immediately after charging a direct indication of SOC. In order to charge a lead acid battery from a 'bit flat' to 'full' , various voltages are applied at various stages (Managed smart charging, CC/CV), and only at the end of all these stages is the battery considered full (And even then, only measurable as such after 8-12hours of rest period and with temperature correction factors). Full also means different things. Just because the battery reached the target voltage and behaved normally, it may still be 'smaller' than its rated capacity. I know you have a new one but it is worth keeping in mind.

All you can really use the BM2 for is to see:

1) When the vehicles is properly charging the battery (14+ volts, done when the car is powered up and drivers door closed I believe)
2) When the vehicle is floating the battery (13.3v , this is during home based 240v HV charging, this is assuming the 12v is 100% charged, but the car doesn't really check this or have any way to know)
3) When the voltage is going down (either slowly in the 12 hours proceeding the charge, or when some external component is flattening the battery).
4) Pinpoint at what times the above happens.

Every battery is different so it will take a while to work out what is normal and what is abnormal.

You can see my recent postings about my BM2 results on a Yuasa 55ah battery (larger than OE):
viewtopic.php?f=11&t=1603

I only ever view voltage.
'21 e Advance - Charge Yellow - E1702RR alloys
'17 Civic Sport CVT
'00 Prelude 2.2VTi
5thcivic
Posts: 154
Joined: Wed Jun 16, 2021 6:50 pm

Post by 5thcivic »

Can you get a seperate lithium battrey to run the dashcams when parked, that only draws recharging from the 12V when the car is on, from usb or lighter socket?
MrM83
Posts: 62
Joined: Fri Dec 08, 2023 10:19 am

Post by MrM83 »

I was wondering that too. I started to look into it but the ones I found were for specific cameras. I’ll take another look.
MrM83
Posts: 62
Joined: Fri Dec 08, 2023 10:19 am

Post by MrM83 »

Here is an interesting observation.

Car is not plugged into charge the HV battery and is locked, but I fastened the driver seatbelt. BM2 is showing the battery hit 12.39v and then is now showing status “charging” with the voltage being 14.53v for the last hour.

Is this expected?
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