12V battery charging

[Rolfe]

It's on the same screen as the tyre pressures, although it's easy to overlook it. Middle button on the right-hand steering-wheel joystick, and scroll horizontally.

 

[Kithmo]

I rarely go lower than 50% SOC on mine which may be why I've had no problems with the 12v.

 

[Rolfe]

I'm sure I read somewhere that the car (SR at least) should be left at a high state of charge if it's not going to be driven for some time, but I can't remember where. I don't remember a reason being given, either. It would be very interesting if people who have left their cars for several days and either experienced or not experienced trouble could remember what the SoC was when the car was parked up. (Mine was on 69% and I had no trouble for over a fortnight. I didn't use the app at all.)

 

[OriginalBigAl]

You can buy lead/acid battery booster packs. I had one for my Peugeot, which had some sort of parasitic drain problem that was never identified. That finally leaked and got dumped, but I bought a new one in 2018 when my Golf was due to be parked up for ten weeks at Avonmouth docks. That's the one I had with me this week in case the MG4 ran into trouble.

Unfortunately I dropped it on the concrete garage floor when I was charging it up and cracked the casing. I have no idea whether it's still serviceable after that.

I,m thinking small maintenance free 12v motorcycle battery because its light ,small, and hopefully if someone can give advice, have enough power to boost the cars 12v to get the car to power up. It will need an occasional charge and although I have not checked, it could be fitted somewhere under the bonnet ready for use should the unfortunate occur. I do have another use for it but thats for a future post.

 

[Rolfe]

I'm not sure how the size of the lead-acid booster pack compares to a motorcycle battery (my bike had 6v electrics, so I don't know). However it's significantly lighter than a regular ICE car battery and has a convenient handle to carry it with. It also just needs an occasional charge. although I don't think you'd get it under the bonnet with the present space-profligate layout of the MG4 in there.

 

[PeteC]

In another thread someone said something about the car not topping up the 12v if the HV battery is at a relatively low state of charge. I can see the logic for this if the HV is really really low, because it will be easier to get a boost for the 12v and get going than to sort out a dead propulsion battery. But the figure mentioned was 50%. Stopping 12v top-up to spare the HV at such a high SoC seems senseless, but if this is true it might explain a few things.

You'd think 50% would have oodles to spare for the 12v battery. My car was somewhere in the 60 per cents when it died so I guess something must have drained the battery. It's behaving fine again at the moment.

I'm sure I read somewhere that the car (SR at least) should be left at a high state of charge if it's not going to be driven for some time, but I can't remember where. I don't remember a reason being given, either. It would be very interesting if people who have left their cars for several days and either experienced or not experienced trouble could remember what the SoC was when the car was parked up. (Mine was on 69% and I had no trouble for over a fortnight. I didn't use the app at all.)

I once left mine on 66% for just over 6 weeks and it was fine. Was on a similar SoC when I left it for less than 2 days and it died!

 

[Rolfe]

Anything that could have caused a parasitic drain?

 

[PeteC]

Anything that could have caused a parasitic drain?

I guess something must have but I don't know what. There was nothing left on or plugged in.

 

[Rolfe]

I had a (petrol) Peugeot 306 that did this at unpredictable intervals and the cause was never found. But it was a fairly old car when the problem developed.

 

[OriginalBigAl]

There is another option, I have a battery charger from Lidl which charges a car battery with 14v through what appears 2mm cables. Having a twin core cable 4mm around 3-4metres long with crocodile clips on all 4 ends. This would not take up much space and accessibly stored and should the worse happen appeal for help from another motorist for a quick boost. It only needs enough time/power to wake up the cars main electrics and put it into ready mode. You,ll have to work out how to get off the seat to remove the cables and shut the bonnet.?

 

[Peter Adams]

How do I connect a solar trickle charger inside the car when the cigaret lighter is not live all the time?

 

[Ian Key]

How do I connect a solar trickle charger inside the car when the cigaret lighter is not live all the time?

You might be better posting your question on the MG5 forum

MG5 EV Forum

Discussions and information about the original MG5 and the 2022 refreshed MG5 Long Range and Trophy Long Range electric estate cars

www.mgevs.com

 

[Tight Git]

For anyone wanting the Noco power banks/jump starters - they are on offer on Amazon at the moment with 29% off.

 

[siteguru]

Example:

https://www.amazon.co.uk/NOCO-GB20-UltraSafe-Lithium-Gasoline/dp/B015TKPT1A/

 

[Tight Git]

Needed one yesterday when my 12v battery failed without warning but have bought a new battery instead.

One interesting observation was the traction battery hasn't done a proper equalisation charge for a couple of weeks despite trying about 5 times - maybe this was a symptom of the 12v battery starting to fail.

 

[fnegroni]

Needed one yesterday when my 12v battery failed without warning but have bought a new battery instead.

One interesting observation was the traction battery hasn't done a proper equalisation charge for a couple of weeks despite trying about 5 times - maybe this was a symptom of the 12v battery starting to fail.

Remember to fully trickle charge a brand new 12v battery before first use.

 

[Tight Git]

Remember to fully trickle charge a brand new 12v battery before first use.

It will be going on my Accumate optimiser later today!