Lithium's and protecting the alternator

[Kevin D Pem]

When a solar controller is set for lithium it becomes a constant current device.
The controller is designed to protect the batteries, not the power source.
You need a device that is designed to protect both.

 

[Richpatty]

I like the idea of a diode to do this, but I am not just that knowledgeable of them and the many variables that happen between the alternator and lithium's.

Next time I go to Freightliner, I may ask them if they see many alternator failures with lithium's, but will have to wait until December.

 

[Kevin D Pem]

What you need to know!
Diodes drop voltage.0.5 volts. Basically a resistor in this application. 10 awg wire also a resistor, but resistance varies depending on heat buildup. .
The hotter the wire the greater the chance the insulation can melt. Although the wire will supply the resistance required for voltage drop needed for the 12vdc circuit I would use an automatic reset breaker at both ends of the wire.

Like I said, I have a unit that I use for my poor boy generator that offers me 12v or 24v battery charging that could easily be modified to protect the alternator. It would need a factory computer tweak maybe.

 

[Richpatty]

Thanks Kevin. I guess I am looking for something that would do something like a DC to DC charger and provide a consistent 30-60amp flow. I am not sure how many diodes I would need as I am not sure how much amperage is coming across....

It would also stop the charging of the chassis batteries on shore power and the function of the booster switch.

Wondering if the battery switch is the way to go....

 

[Kevin D Pem]

Thanks Kevin. I guess I am looking for something that would do something like a DC to DC charger and provide a consistent 30-60amp flow. I am not sure how many diodes I would need as I am not sure how much amperage is coming across....

It would also stop the charging of the chassis batteries on shore power and the function of the booster switch.

Wondering if the battery switch is the way to go....

The real problem is with dry campers and long weeks without charging. I would guess that really isn't what you do, so the switch would likely work for you.

 

[Joe Hogan]

We had 640+ amp of LiFePo and solar installed in our Canyon Star. Never had an issue with the alternator charging the batteries. The stock Bird failed once but other than that no issues. For whatever that is worth.

here is a good source of information

Careful - Alternator Charging Lithium - Victron Energy

Charging lithium batteries from an alternator, be that in a boat or vehicle, presents some challenges when compared to the straightforward nature of charging lead based batteries. The video in this blog highlights these lithium challenges and shows you what can happen when things go wrong –...

www.victronenergy.com

 

[Rich W.]

Solar makes all the difference - the batteries are almost never discharged very much when you hit the road. But even without it, I’d just make sure I’m charged up pretty well before driving to prevent an excessive load on the chassis charging system.

 

[Ventana]

Does a DC to DC charger address these issues?

 

[Richpatty]

Does a DC to DC charger address these issues?

Yes, but how do you put it in place without disruption the charging of your chassis batteries from shore power and the aux boost function? You would need to remove the BIM which handles those functions.

 

[Neal]

Are there any reports of an alternator failing? Would an alternator "fail" just because the demand for amps is higher than its output? I hear they are quite robust. I think I'd just let things go and if it fails then correct for next time around but my guess is it is not going to fail. Maybe over-engineering the situation? Maybe also someone that sells LifePO4 batteries for RVers can shed some light on this topic?