Replacement 12v battery

[ArthurUK]

Swapping the Lead Acid Auxiliary Battery for any kind of Lithium Cell(s) Battery is the issue.
The dedicated charging system for the auxiliary Battery is designed for Lead Acid.
Its unlikely Mitsubishi would approve this change, so the warranty would be void.

Whatever flavour of Lithium Battery is safer is not relevant.

 

[yardbird]

I had extended warranty till 90K and had no problem in obtaining warranty services at all. e.g. got the following warranty services as such.
1. The whole front axle was replaced by dealer for one leaking boot.
2. The front suspension system was replaced due to bad shock & broken dust boots replaced by third party paid for by the warranty service company.

Mitsubishi extended warranty never questioned the lithium battery at all. My 2018 PHEV is now over 92K miles. LiFePo4 12v battery in my PHEV has a built-in BMS chip inside to regulate any overcharging from the main battery pack. Other than the 10-12 EV miles, Happy camper!

 

[HHL]

The Outlander charging circuit will be designed for Lead acid, the charging V/I profile is very different to Lithium.
Plenty of advice on Google, this explains the difference:
https://enerdrive.com.au/2024/07/24/can-i-charge-my-lithium-battery-with-a-lead-acid-charger/?
You run the risk of it catching fire.

It seems to be simply a constant voltage charger, it is not current limited to what the specification on the original yuasa battery recommends. No fancy profile there..