Limiting current to Aux battery?
I have a campervan with a 90A OEM alternator. I am using a standard deep cycle lead acid flooded marine battery under the hood as my aux battery. I use a 100A relay to parallel the starting and aux ba...
Forum Discussion
Battery science says if you hit a depleted wet cell deep cycle battery with 14.4VDC it will only demand 17-20AMPS of DC charge current and it will bring this up to its 90% charge state in a three hour period. It will bring it up to its 100% charge state in about 12 hours of total charging... If you want to charge faster then you have to increase the charge DC Voltage and of course it will demand more DC current doing this. It will also start boiling out your battery fluids and the case will get hot and it may explode on you...
If you have a shorted cell in a battery your inline fuse between the battery and the charge source would open the circuit if the batteries is demanding very high DC current...
The bottom line here is the batteries demand how much current you are using. i.e. you could have 300AMPs available to us and it will only demand 17-20AMPS per battery that is being charged together with 14.4VDC charging Dc Voltage. If you have two batteries to be charged it will demand 34AMPS to 40AMPs DC current when using 14.4VDC charging DC Voltage. If you don't have that much DC current available it will still charge your batteries but will take much longer to do it...
If you install one of the BLUE SEA SI-ACR smart relays for charging batteries it will only connect your aux battery when the alternator is producing 14.4VDC charging voltage. I think the relay trip is set to 14.2VDC. This is the only time the two batteries (Truck Start Battery and AUX Battery) will be demanding current together from the 90A Alternator setup...
It would be alot better of course if you had a bigger ALternator.
I know what I would in your situation and that is to monitor the status of the AUX battery and when it got down to its 50% charge state I would fire up my 2kHonda Generator and recharge it back up to it 90% charge state in three hours using a smart mode battery charger or perhaps a PD9200 series converter/charger that runs off of 120VAC...
Always choices
I am one of those to never do anything to the truck start system setup. This is the only way you get back home on haha...
Just some of my thoughts here...
Roy Ken
If you have a shorted cell in a battery your inline fuse between the battery and the charge source would open the circuit if the batteries is demanding very high DC current...
The bottom line here is the batteries demand how much current you are using. i.e. you could have 300AMPs available to us and it will only demand 17-20AMPS per battery that is being charged together with 14.4VDC charging Dc Voltage. If you have two batteries to be charged it will demand 34AMPS to 40AMPs DC current when using 14.4VDC charging DC Voltage. If you don't have that much DC current available it will still charge your batteries but will take much longer to do it...
If you install one of the BLUE SEA SI-ACR smart relays for charging batteries it will only connect your aux battery when the alternator is producing 14.4VDC charging voltage. I think the relay trip is set to 14.2VDC. This is the only time the two batteries (Truck Start Battery and AUX Battery) will be demanding current together from the 90A Alternator setup...
It would be alot better of course if you had a bigger ALternator.
I know what I would in your situation and that is to monitor the status of the AUX battery and when it got down to its 50% charge state I would fire up my 2kHonda Generator and recharge it back up to it 90% charge state in three hours using a smart mode battery charger or perhaps a PD9200 series converter/charger that runs off of 120VAC...
Always choices
I am one of those to never do anything to the truck start system setup. This is the only way you get back home on haha...
Just some of my thoughts here...
Roy Ken
