Is the 12v Auxiliary Battery dead?

[Am786]

My phev intermittently shows the EV Stop Message and warning lights.

If I leave it for a bit most of the time it then restarts. Today, it refused to start, fortunately I was next to my wall charger, plugged that in - charged for 5mins - then everything started up as usual.

I think the 12v battery is on it's last leg.

I took a volt reading and it was changing from 12.56 to 12.49 - admittedly I don't know if I've got it on the right setting.

questions:
1. Is it worth recharging the battery, a battery charger costs around £40 and perhaps it will then allow me a few more years on the battery?
2. If I needed to replace the battery, are there any alternatives to the Tayna battery (Yuasa HJ-S46B24L(S) Auxiliary Battery 12V 45Ah, Enduroline HJ-S46B24L(S) Mitsubishi PHEV Auxiliary Battery 12V 45Ah) as they seem to be out of stock for a while now?

Thank you in advance.

 

[davebodger]

Yes, from what you discribe it sounds like the battery needs replacing. Unless you are regularly running the battery down with accessories when the car is not in READY mode, charging it will only help for a little while. The car charges the battery for a bit at 2pm every day to stop it running down due to basic loads, like the alarm system, in case you do not use the car for extended periods.
When the car is "READY" the in-built charger should, assuming lights, heater and blower etc. are all off, charge the battery at 14 to 14.5 volts.
So at less than 13V while charging it is likely at least one of the cells is on it's way out.
The in-built charger is quite high-capacity and can easily run all 12V loads and charge the battery at the same time and is not dependant on engine speed like an ICE car as it runs directly off the traction battery. It is not an alternator, the ICE engine in the PHEV does not have one.

Regarding a replacement, I was looking at this one from Halfords Yuasa HSB053 Silver 12V Car Battery 5 Year Guarantee | Halfords UK - basically as long as the size is right and the battery terminals are in the right place then pretty much any 12v battery will do; however I did note that the one in my 2014 PHEV seems to have small diameter terminals (Japanese?).

 

[AndyInOz]

May I respectfully suggest that you may regret putting a cheap battery into the interior of a car, especially after a collision. (Getting covered in battery acid while being trapped in your seat doesn't sound like something I'd want to do.)

Make sure that any battery matches the specification of the battery that is currently in the car.

At the very least, make sure that is it an Absorbent Glass Mat (AGM) style battery designed to be mounted in the interior of a car.

 

[Am786]

Yes, from what you discribe it sounds like the battery needs replacing. Unless you are regularly running the battery down with accessories when the car is not in READY mode, charging it will only help for a little while. The car charges the battery for a bit at 2pm every day to stop it running down due to basic loads, like the alarm system, in case you do not use the car for extended periods.
When the car is "READY" the in-built charger should, assuming lights, heater and blower etc. are all off, charge the battery at 14 to 14.5 volts.
So at less than 13V while charging it is likely at least one of the cells is on it's way out.
The in-built charger is quite high-capacity and can easily run all 12V loads and charge the battery at the same time and is not dependant on engine speed like an ICE car as it runs directly off the traction battery. It is not an alternator, the ICE engine in the PHEV does not have one.

Regarding a replacement, I was looking at this one from Halfords Yuasa HSB053 Silver 12V Car Battery 5 Year Guarantee | Halfords UK - basically as long as the size is right and the battery terminals are in the right place then pretty much any 12v battery will do; however I did note that the one in my 2014 PHEV seems to have small diameter terminals (Japanese?).

Thanks for the comprehensive reply, and I think I agree - time for a new battery.

I read somewhere that there were two types of terminals - the Yuasa model ending in L had larger terminals (European) than the the Yuasa model ending in R - I'm guessing you have the R model Japanese.

 

[Am786]

May I respectfully suggest that you may regret putting a cheap battery into the interior of a car, especially after a collision. (Getting covered in battery acid while being trapped in your seat doesn't sound like something I'd want to do.)

Make sure that any battery matches the specification of the battery that is currently in the car.

At the very least, make sure that is it an Absorbent Glass Mat (AGM) style battery designed to be mounted in the interior of a car.

Understood and completely agree - will be getting the Yuasa same model and make.

 

[Am786]

Yes, from what you discribe it sounds like the battery needs replacing. Unless you are regularly running the battery down with accessories when the car is not in READY mode, charging it will only help for a little while. The car charges the battery for a bit at 2pm every day to stop it running down due to basic loads, like the alarm system, in case you do not use the car for extended periods.
When the car is "READY" the in-built charger should, assuming lights, heater and blower etc. are all off, charge the battery at 14 to 14.5 volts.
So at less than 13V while charging it is likely at least one of the cells is on it's way out.
The in-built charger is quite high-capacity and can easily run all 12V loads and charge the battery at the same time and is not dependant on engine speed like an ICE car as it runs directly off the traction battery. It is not an alternator, the ICE engine in the PHEV does not have one.

Regarding a replacement, I was looking at this one from Halfords Yuasa HSB053 Silver 12V Car Battery 5 Year Guarantee | Halfords UK - basically as long as the size is right and the battery terminals are in the right place then pretty much any 12v battery will do; however I did note that the one in my 2014 PHEV seems to have small diameter terminals (Japanese?).

The one from Halfords seems to match however their website tells me it is not suitable, perhaps it's not compatible as an AGM battery

 

[DaveL59]

Be useful to say which model and age vehicle you have I think. The base spec models do not have WiFi so don't charge the battery daily when unused.

My 2019 4HS battery shows 12.2 down to 11.8 (so 60% to 30/40% charge) at the terminal under the bonnet and runs the car just fine. After charging it for 7 hours using a smart charger it settled at 12.26v, much worse than your readings and I'm considering it to need replacement once I can obtain a new battery for it.

If you take the car for a run, the charging system will be delivering around 14.5v which will drop over time to 13.6v once it deems the battery has had enough charge. I monitored this yesterday on a 200 mile round trip since I installed a USB outlet which has a volts display. My battery still only displayed 12.2v after resting for several hours before making the return trip.

It is of course possible one of the cells in yours is very weak so the volts drop quickly once a load is applied but at 12.56 it may still be healthy as that indicates potentially 80% charge. What does the voltage read if the car has been left unused for a few hours, so the battery has had a change to settle?

Recondition charging might help tho probably not that much.

 

[SiNJiN]

https://amzn.eu/d/fGzYTyK
That's the battery I got fit my 2019 4h

 

[Am786]

Car is a 2015 gx4hs with WiFi

My brother had a smart charger, so for now I've put it on trickle charge and getting a constant 12.9v

I'll leave it for a week or two and see how it goes then probably replace it if it happens again.

Thank you all for your help

 

[DaveL59]

For an AGM battery my CTek puts out around 14.7v when charging, dropping to 13.6v float/trickle. Is that charger on the initial phase at 12.6v as I'd expect more. I assume if its smart it has either self-switched to AGM mode or you've set it to that?

 

[Stevepl11]

Here's something just for the sake throwing a bit of information at you. In the main fuse box where the jump/charge terminal is, the is a fuse labelled IOD, which turns out to be Ignition Off Draw. It is rated at 30Amps which seems to be more than necessary. I wanted to make some measurements so I replaced it with a 4 Amp (Yes Four not Forty) fuse and tried to measure any voltage drop across it to then maybe translate into current if I could determine the resistance of the fuse. Well I couldn't really measure anything so I just left it there to see what happened. The car performed completely normal for several months, maybe even a couple of years. I don't know, but long enough to forget how long it was. Then one day while listening to the radio and waiting for a food pickup and the car only in accessory mode. It just died. Nothing worked. That 4 Amp fuse had blown while the system was not running, so no charging from the DC-DC converter. Replaced the original fuse and all ok. I would not have expected the radio to run from that fuse, maybe it does so other settings done via the infotainment screen are preserved.

 

[Am786]

For an AGM battery my CTek puts out around 14.7v when charging, dropping to 13.6v float/trickle. Is that charger on the initial phase at 12.6v as I'd expect more. I assume if its smart it has either self-switched to AGM mode or you've set it to that?

Yes, I set it to the AGM mode so it started at 13.6v then settled at 12.9v after four bars were reached (four being fully charged)

 

[DaveL59]

Checked my daughter's car today after it'd been parked a few hours, 12.6-12.4v and seems to have no issues, 2018 2.4L 4H. So much better than my 2019 4HS that gives best 12.2 and more usually 12.0-11.8v tho so far it still runs the car just fine.

 

[edanto]

https://amzn.eu/d/fGzYTyK
That's the battery I got fit my 2019 4h

Thanks for including this link. Showing out of stock but I’m also looking to replace my 12V so will try find this model elsewhere.