Thread: Lithium Battery on a D300

As far as i know there 2 drawbacks with using a lifo battery for cranking 1 is that it usually means under bonnet installation and engine bay heat and 2nd is the ability of the BMS to handle the alternator output of 100a plus, but i believe the L663 has its battery has its battery under the floor or in the cargo space so heat wont be an issue so as long as the BMS can handle the higher charge rate you should be good.

Originally Posted by loanrangie

As far as i know there 2 drawbacks with using a lifo battery for cranking 1 is that it usually means under bonnet installation and engine bay heat and 2nd is the ability of the BMS to handle the alternator output of 100a plus, but i believe the L663 has its battery has its battery under the floor or in the cargo space so heat wont be an issue so as long as the BMS can handle the higher charge rate you should be good.

you are right that the battery is under the drivers seat. So now I just need to figure out the BMS challenge. Thanks for the feedback.

Hi James and there are a number of things to consider when thinking about fitting a lithium cranking battery in ANY vehicle with a SMART alternator charging system.

But first and foremost, if the vehicle has a SMART alternator then around town, you can keep a lithium cranking battery in a reasonable state of charge, particularly if you are doing lots of short drives.

BUT, with the very way you want to use your cranking battery to run a fridge, you may be very disappointed if you drive for some time before stopping for the night.

Vehicles with SMART alternator operation regularly run at voltages as low as 12.5v on long trips. But lithium batteries have a fully charged voltage of 13.3v, which they maintain for around 80% of their discharge cycle.

So on a long trip, when your vehicles charging voltages drop to around 12.5v but the lithium battery will be sitting at 13.3v and the instant your vehicles charging voltage drops below 13.3, you vehicle will now be electrically powered by your lithium cranking battery.

So you could leave home with a fully charged cranking battery, drive for 2.5 hours or more before stopping for the night and you will not have enough energy left in your cranking battery to run your fridge over night.

BTW, this is a common problem with D4s running lithium cranking and auxiliary batteries.

This is a known problem with any vehicle with a SMART alternator operation and the sellers of these lithium cranking batteries just forget to tell their customers.