toban

This car has a 48 volt lithium battery that powers a starter generator. There are no belts. The generator also runs the water pump and serves as the alternator also.

If I want to charge this battery, it is also connected to the AGM auxiliary battery. Can I place a trickle charger on the battery connectors under th hood in order to charge both batteries?

The dealer once again could not answer this question. There are 3 batteries in this car. The 48 volt lithium battery, AGM auxiliary and a small 12 volt battery that runs the start/stop feature.

Can anyone shed some light on this subject for me who owns one of these models?

Thanks again.

Toban

Wiggis

The car's system electronics operate off 12v supplied by the AGM battery, supplemented by the 12v auxiliary battery for when the engine is not running. The 48v lithium battery is charged via the integrated starter generator whenever the engine is running. The oil pump, water pump, power steering, and air conditioning compressor are all 48v and powered by the lithium battery. The 12v AGM battery is capable of being charged via the terminals under the hood / bonnet, and also through a DC to DC converter from the 48v integrated starter generator supply, but again, only when the engine is running. The 12v auxiliary battery is only charged up when the engine is running.

As far as I am aware, there is no way to charge up the 48v battery other than by running the engine - the DC/DC converter just does 48v to 12v, and not the other way around. That said, the 48v battery is quite limited in capacity, and the integrated starter generator kicks out a hell of a current when it's running - doesn't take very much running to fully charge it.

In short - the terminals under the hood / bonnet only charge up the 12v AGM battery. Everything else is charged only when the engine is running.

mikapen

Here's from Daimler: https://media.daimler.com/marsMediaS...l?oid=22934110

toban

Thanks for your reply. Another question:

what might happen to the 48 volt battery if the car sits for say 2 months in a garage? Will the battery be dead when I return? I understand there is a standby mode you can put the car in to close off all electrical draws?
Your comments are once again appreciated as the dealer really doesn’t have an answer.

Toban

Wiggis

There is a very sophisticated power management controller for the 0.9 KWh lithium battery. Lithium batteries tend to lose 1% power per day from full when doing nothing, so remaining power drops in a curve, and it will switch to a very low power preservation mode at about 11% charge level to retain that level for a very long time. I think you’d need to not use the car for at least six months for it to ever be a problem, and even longer before you’d be in a no start situation. The 12v AGM battery would be dead long before the lithium battery had a real problem.

I think the key thing is to run the vehicle for 30 minutes or more at least once every two weeks, and it will be fine. They’re just not designed to sit doing nothing for months on end, but even if you did that, I believe the lithium battery would be just about OK for six months or so.

As they say. Your mileage may vary. The thoughts above are my best guess at what would happen.

toban

Hi Wiggis, thanks for your help.

Have you any information on the engine block heater question I posted?
I live where it is cold in winter.

Toban

Brer Rabbit

Does page 584 in the owner's manual address your question?