Lithium batteries and alternator protection.

This is what we did, A 30amp DC to DC charger gives you the ability to charge the coach battery bank while running the coach engine.
This limits the engine alternator to 30 AMPs thus prevents overheating the engine alternator.
The engine alternator will operate normally while charging the engine batteries.
We have had the system in service for 2 years, with no problems.

Tom/Barb wrote:
This is what we did, A 30amp DC to DC charger gives you the ability to charge the coach battery bank while running the coach engine.
This limits the engine alternator to 30 AMPs thus prevents overheating the engine alternator.
We have had the system in service for 2 years, with no problems.

Tom/Barb
What brand and model did you use??

Thanks
Kent

N6WT wrote:

Tom/Barb wrote:
This is what we did, A 30amp DC to DC charger gives you the ability to charge the coach battery bank while running the coach engine.
This limits the engine alternator to 30 AMPs thus prevents overheating the engine alternator.
We have had the system in service for 2 years, with no problems.

Tom
What brand and model did you use??

Thanks
Kent

4 Battleborn.. and victron
Our system is....
1- 3000 watt inverter /charger (VICTRON)
4- 100 Amp Hour battleBorn batteries.
1- 30 Amp DC to DC charger (victron)
and 1 Blue tooth donggel (sp) to monitor the system on my phone.

A 30A DC DC could pull 45 amps. Output is 30

If you have time at one place I recommend measuring the charging amps and then decide if the DC-DC is needed. Depending on wire size and length along with alternator rating there may not be any issue. A DC clamp-on ammeter will tell the actual story.

Also consider the DC-DC charger will isolate the house battery such that any existing combiner to maintain the chassis battery could become non functional.

Going to really like the BB power.

BFL13 wrote:
A 30A DC DC could pull 45 amps. Output is 30

I never see that current in our system.

our coach batteries are monitored on the OEM gauge in the engine to 13.2 vdc
our house batteries are monitored on the Victron gauge at 14.2 vdc
the DC to DC charger is limited to 30 amps by two fuses on the + side of the circuit.
the house battery bank is controlled by 1-300 amp fuse in the + plus side and 500 AMP shunt and a shutoff switch in the Negative side of the buss.

time2roll wrote:
If you have time at one place I recommend measuring the charging amps and then decide if the DC-DC is needed. Depending on wire size and length along with alternator rating there may not be any issue. A DC clamp-on ammeter will tell the actual story.

Also consider the DC-DC charger will isolate the house battery such that any existing combiner to maintain the chassis battery could become non functional.

Going to really like the BB power.

the size of the DC to DC charger you need will be determined by the size of the engines alternator.
The victron DC to DC charger can be set for the system requirements by blue tooth remote.

time2roll wrote:
If you have time at one place I recommend measuring the charging amps and then decide if the DC-DC is needed. Depending on wire size and length along with alternator rating there may not be any issue. A DC clamp-on ammeter will tell the actual story.

Also consider the DC-DC charger will isolate the house battery such that any existing combiner to maintain the chassis battery could become non functional.

Going to really like the BB power.

I have read about this and normally on a truck and trailer you may not need the DC to DC charger because of the length and wire size. On a class A motorhome the alternator is much closer to the batteries and I am assuming the wire size is bigger also ( I need to check the wire size).

Yes I am looking forward to the advantages of the lithium batteries.

Thanks
Kent
N6WT

N6WT wrote:
Eventually I will be adding solar.

We didn't see a reason for solar, We spend much of the time plugged into 50 amp service, when we are traveling the engine alternator will charge the batteries. When are parked, we can go about 4 days with out charging.
for us, that is enough.

unless we run the 2 air-conditioners. then solar will not help

Tom/Barb wrote:

BFL13 wrote:
A 30A DC DC could pull 45 amps. Output is 30

I never see that current in our system.

our coach batteries are monitored on the OEM gauge in the engine to 13.2 vdc
our house batteries are monitored on the Victron gauge at 14.2 vdc
the DC to DC charger is limited to 30 amps by two fuses on the + side of the circuit.
the house battery bank is controlled by 1-300 amp fuse in the + plus side and 500 AMP shunt and a shutoff switch in the Negative side of the buss.

If the DC-DC is charging the house batts with 30 amps at 14.2v , that is 426 watts output. Input must be at least that in watts, more for charger efficiency say 90% to be generous so needs 469 watts.

If input is that 13.2v (not clear from the above info) that means input amps must be at least 469/13.2 = 35.5 amps draw on the engine side (engine batt/alternator.

If the engine batts are 13.2 (seems low) then with wiring loss voltage drop between engine batts and DC-DC charger input voltage will be less than 13.2 so the input amps would have to be higher than that 35.5

Best way to measure what is going on is with your digital multimeter right at the input and output terminals of the DC-DC charger itself for the two voltages.