My new LiFePO4 12V battery

[Munnsy]

Hearing that some people have had issues about the factory standard 12v lead acid battery going flat and not lasting very long,

I have bought and fitted a 40 Ah LiFePO4 battery.

Many of these batteries are not suitable for year round automotive use as they cannot accept a charge at temperatures under 0c degrees,

But this is a "Sub zero" type from the UK company Beyond Batteries, good for as low as minus -20°C.

SUB-ZRO 12.8V LiFePO4 40Ah 512Wh - Ultra Low Temperature Battery

SZ40 Sub-Zero LiFePO4 40Ah ultra-low temperature charging battery for solar. No loss to heaters, powers CCTV, security pods, and outside monitoring systems.

beyondbatteries.co.uk

Fitting was easy, only slight hassle is the terminals on this battery are on the wrong side, so I used some very hefty 2 AWG gauge cable (way overkill) to bridge across to the terminals. Seemed a much better solution than trying to pull the factory cables into a position they didn't want to sit and risk cable damage..

I can/will swap the original battery back in for when the car goes to the main dealer for a service.. just in case they don't like it.

Also I fitted a new battery fabric strap, the original was too slack.

Another bonus, I have saved a whopping 6.5kg compared to factory!

...Yes I know i need to find a little rubber boot to fully cover the positive terminal!

 

[Munnsy]

The battery has Bluetooth built in and you can use the Beyond Battery app to view the charge and discharge status...

Car is currently plugged in at home charging the main EV battery, and voltage on the LiFePO4 is spot on.

 

[OriginalBigAl]

Looking good , keep us informed about its longer term usage please. Have you buggered up your 50/50 weight distribution ?

 

[Munnsy]

Looking good , keep us informed about its longer term usage please. Have you buggered up your 50/50 weight distribution ?

Thanks. haha.... If I go on a diet to lose the same weight myself, it will even out lovely as drivers side is opposite the battery!

Car has now been off charge for a few hours...settled at 13.3v, a great resting voltage.

 

[Munnsy]

Brilliant. A week on and voltage is still 13.3v. car was only used once last week and it's now had about 4 days sitting idle.

 

[Chrisdriving]

What's the benefit over say a decent AGM battery that is more standard?

 

[Munnsy]

What's the benefit over say a decent AGM battery that is more standard?

Mainly for the weight saving and the lifespan...Lifepo4 should last 8-10 years.

Another slight issue for a AGM battery on a non AGM intended car... it won't fully charge. AGM require 14.6-14.8v to reach fully charge.

The MG4 charging system will only output 14.2- 14.4v maximum.

You really should stick with a quality brand standard lead acid battery rather than AGM, it isn't a upgrade if the charging system is not designed to work with it.

 

[Chrisdriving]

Fair comments, dunno how long my MG4 one will last but my Leaf one is still original battery on car from 2016.

 

[Munnsy]

Fair comments, dunno how long my MG4 one will last but my Leaf one is still original battery on car from 2016 a high quality brand used on the Leaf...I think you would be doing well for the MG4 factory battery to last longer than 3 years.

That must be a very decent quality battery on the Leaf! I don't think the factory battery on the MG4 will manage anything like that. 2-3 years more likely.

 

[m4rmite]

I'm still on my original 12v battery on my mg5 after very nearly 5 years.
I do expect it to give me grief 1 day so I am interested in a lithium 12v battery come the time.

 

[Evies Owner]

The charging system is designed to work with a 12v lead acid battery profile. Sorry, but a Lithium battery has a totally different discharge profile. As you have already observed, "A week on and voltage is still 13.3v", and it will likely stay there until it drops to 13.1v where it will sit until just near the end when it will drop rapidly.

 

[Munnsy]

The charging system is designed to work with a 12v lead acid battery profile. Sorry, but a Lithium battery has a totally different discharge profile. As you have already observed, "A week on and voltage is still 13.3v", and it will likely stay there until it drops to 13.1v where it will sit until just near the end when it will drop rapidly.

Yes. But it's still showing full on the battery app

99% . Taken just now. (Car has been parked locked since Sunday)

I've noticed the IN/OUT Amps and Watts does not display a charge or discharge if less than 0.6amp

Highest load I have seen so far sitting still in the car is about 6 amps with headlights on main beam, heater on full with the heated seats and steering also on. Forgot to turn on rear demister.

 

[EvTek23]

I like the Idea of the the different technology, the IM range uses a lithium auxiliary 12V battery.
Possible drawbacks could be the cell disconnect at 10V, so if ever it does fall down that cliff edge it will just disconnect. It would be a right struggle then to get into the car. Would you then have to disconnect the battery to be able to charge it again?
The webbing strap might also be an issue, being regarded as not properly secured.

 

[Munnsy]

I like the Idea of the the different technology, the IM range uses a lithium auxiliary 12V battery.
Possible drawbacks could be the cell disconnect at 10V, so if ever it does fall down that cliff edge it will just disconnect. It would be a right struggle then to get into the car. Would you then have to disconnect the battery to be able to charge it again?
The webbing strap might also be an issue, being regarded as not properly secured.

The battery still has the factory clamp in place so it can't slide forward. It rests against back of tray also.
The base of the battery and the tray have also been covered in this proper Velcro.