I like to boondock. I currently have 4 AGM batteries for a total of about 480 amp-hours, of course only about 200 useable. I would like to purchase some lithium batteries and put together a system of 400-500 amp-hours, about the same capacity.One thing that is holding me back is what will happen that morning when I drive away from camp with depleted batteries and all the charging load goes on my alternator. It is a Lestek dual-output rated at about 130 amps. It puts out a constant voltage around 14.1 volts. I've seen videos of fried alternators. Can my alternator handle that load, or would I need to add some kind of temperature and voltage regulated system and/or a regulated DC-DC charger?Thanks for your wisdom.

Hi,A dc to DC charging device would protect the alternator. For a quality device, look at Victron or Outback.I'm moving to SiO2 batteries myself. They can be used when there is snow on the ground, unlike most LI chemistries and are about 1/2 the price of LI.

From a U.S. hospital room...Lestek, put out a good aftermarket product. One stator 2 complete rectifiers.Enjoy it as is.

My alternator cable to the house batts has to go through a battery isolator and then two 40 amp breakers. That would seem to limit the risk.

steveh27 wrote:My alternator cable to the house batts has to go through a battery isolator and then two 40 amp breakers.Most DC-DC chargers are also isolators.

Find LOAD DUMP on GoogleNever ever put a circuit breaker between an alternator and battery.This is a universal rule observed by SAE for sixty years running.

Alternators and Lithium Batteries | Good Sam Community

pianotuna
Nomad III
Jan 31, 2021
Hi,

A dc to DC charging device would protect the alternator. For a quality device, look at Victron or Outback.

I'm moving to SiO2 batteries myself. They can be used when there is snow on the ground, unlike most LI chemistries and are about 1/2 the price of LI.
MEXICOWANDERER
Explorer
Jan 31, 2021
From a U.S. hospital room...

Lestek, put out a good aftermarket product. One stator 2 complete rectifiers.

Enjoy it as is.
steveh27
Explorer
Jan 31, 2021
My alternator cable to the house batts has to go through a battery isolator and then two 40 amp breakers. That would seem to limit the risk.
theoldwizard1
Explorer II
Jan 31, 2021
steveh27 wrote:
My alternator cable to the house batts has to go through a battery isolator and then two 40 amp breakers.

Most DC-DC chargers are also isolators.
MEXICOWANDERER
Explorer
Jan 31, 2021
Find LOAD DUMP on Google
Never ever put a circuit breaker between an alternator and battery.

This is a universal rule observed by SAE for sixty years running.
2oldman
Explorer II
Jan 31, 2021
You don't have solar?
pianotuna
Nomad III
Jan 31, 2021
Mex,

I believe the starter battery circuit will remain intact.

The OP has a circuit breaker in the house battery charging circuit. Why he would have two such breakers is a mystery.
time2roll
Nomad
Jan 31, 2021
DC-DC charger would provide two benefits. First in limiting your amps, secondly boosting the voltage to 14.5 or 14.6 to actually charge the battery to full. 14.1 is a bit low for most lithium.

Keep in mind the DC-DC charger can draw up to 50% more amps than rated output.

You could put your DC clamp-on ammeter on the charge wire or better the alternator output and see if you really get excessive amps. Test at home during the install. Then get the DC charger if needed.
Son_of_Norway
Explorer
Jan 31, 2021
Thanks to all. I have 300 watts of solar and I could always run the generator for awhile before I leave the campsite. The circuit between the alternator and the batteries stays closed. The videos I have seen indicate the problem occurs at low RPM. I can see the thing to do would be to run some tests when I install the batteries. I just wanted to have some idea of the other components that I will need in addition to the batteries and how much I will have to modify the system I have now.

Mexico, sorry to hear you are in the hospital. I hope you get well soon.
Naio
Explorer II
Jan 31, 2021
Mexxxxxxxx!!!! I'm so glad to hear from you, and so sorry that you are feeling horrible and so glad that you are getting care! I'm not around here much lately, but I heard from Mr tuna that you were MIA, and I have been anxiously awaiting word.