VW Camper Family

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Simple relay, automatic control relay or batteries isolator, wich is the best for my batteries ?

After a couple hour of googling, i finaly get the answer..

Simple Relay : The problem is when the ignition in on, if  the main battery or the auxiliay battery is empty, the will drain the other one.  That can be a problem when you stay long time at the same place.  You could have trouble to start.

Batteries isolator : The solution is most interesting but the voltage drop from the diode inside the isolator make it less atractive.  If the alternator have a 13.5 V output, you will get 12.8 at the batteries.  They never be at full charge...

Automatic contrôl relay :   I do not find any disavantage.. With this setup, you could charge both batteries from the alternator or with another external power source.  When you drive load without power, the relay separte him automatically.   For more information : blue sea relay 7610 :

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Simple relay is fine, you never leave the ignition on long enough for it to be a problem. And it would only be a problem if you had another existing problem!

I used the hot-start kit and simply increased the fuse from 15amps to 20 amps. It can blow if the aux. batteries are to low and the alternator tries to give more juice then the relay can take.

Been working for years.

Good luck,

Bus Boy Bob


Your probably right but i see another big advantage of ACR.

If your van stay long time at the same place, it could be interesting to add a external DC power charger to keep your bateries in shape (main and auxiliary).  With ACR, they automaticly charge and maintain both bateries !


Here we have long winter, in fact, i only have to plug my van on a external outlet to keep my batteries in shape all winter long.

ARC looks good and simple with perks! I may consider it myself.

Let us know how it works out.

We are using a Yandina 100 Combiner. Yandina It is fully automatic, but has a manual overide if you wire in a two way switch. It will not combine for cranking. Works well so far.

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