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I travel 1 1/2 hrs daily to work. Thought I could put a bank of deep cycle batteries in the trunk to charge off my alternator, and then run a small refrigerator and 12V lights in my small home in the eveings. Will this work? Anything I have to consider? Thanks.
How big is the battery and how big is the alternator? It probably will work but if you totally discharge the battery ever night will the alternator recharge it in the available time.
Second thing to consider is whether the charge current demanded by the discharged battery exceeds the capacity of the alternator. You may simply end up burning out the stator windings. Are you driving a small Honda civic with a 30 amp alternator or a big Detroit car with a 90 Amp heavy duty alternator?
There are too many variables for a clear answer, but elnav has given some good info. It’s nice to use the “free electricity” created by your car. One thing that would help would be a low voltage disconnect. That way you can be sure the car will start in the morning and you are not late to work!
I use old fashion kerosene lamps for light and a propane fridge from a camper. I can always count on them to work.
get a split charging relay installed in your car this will resolve your issue see link for a good overview any good auto electrician can ins0-727-23, DURITE 12V, 70A-20A SPLIT CHARGE RELAY
yes its possible here is what i did and yes i have used this setup
a lot over the years
BUT
too many batteries WILL put an excesive load on your alternator
if you run them flat basically you will fry the regulator and maybee even the
rectifiers in the alternator.
from expierience i would recomend not going beyond about 100 AH extra storage
with a normal car/small pickup alternator.
depending on how you set things up your alternator will only trickle charge
your extra batteries so 1.5 hours of driving will not add a lot to your xtra batteries.
there are ways to change the charge rate of your alternator and save your batteries and alternator etc but it takes too much technical knowledge
to set up for most people.I dont know if there is a easy comercial setup
to do this? honestly i have never used the rectifier based isolators and dont know if they will make the most of the charging capacity of a alternator?
but the fact still remains that working the alternator too hard (beyond designe specs) will cause problems.designe specs for most small vehical alternators are bringing a 50 to 100 amp hour battery up to correct charge rate very quickly.(when they try to do this to a large bank they are overloaded)
in short the alternator can put out huge amounts of energy but the regulator
and rectifiers are probably not up to the task right out of the box.
and then in the quest for power from an alternator you will run up against
belt friction/slippage and finally physical bearing strength.
in even shorter short LOL add another 10 amps to you standard alternator
work load and you will probably be ok 10 amps for 1.5 hours is 15 AH which
is not enough (nowhere near) to be running a fridge on a daily basis.
