Recharging via alternator

[Heinz]

<p>Quick question for you electricians out there;</p><p>We need to power our exhaust vent fan, planning on hooking up a battery directly to it, as it's the only thing we have that requires power. How would I go about wiring the battery to the alternator so that it recharges when the van is running? Could I just connect the positive lead to the positive post of the starter battery, then install a switch between where it connects and the fan battery (so it wouldn't drain the starting battery)?</p><p>Or would I have to connect it to the alternator directly? I know this the preferred method, just seeing if it's the only method.</p><p>Thanks,</p><p>-Matthew and Kassie</p>

 

[akrvbob]

Hi Mathew and Kassie, yes, that is exactly the easiest and cheapest method. Run a cable from the positive post of starting battery to positive post of house battery. To keep the starting battery from being run down put a on-off switch between the two batteries. You have to remember&nbsp; to throw the switch, so many people prefer a continuous duty solenoid. It automatically disconnects the two batteries when the key goes off. <br /><br />You must then ground the house battery to the frame. Works really well and is relatively cheap. Be aware it will not keep the house battery fully charged unless you drive a lot. So keep a volt meter on the battery so you never run it down past 12.2. Bob

 

[Heinz]

<p>After spending most of today trying to figure out how to hook up an isolator, I've decided to just go with the switch method. What kind of switch do I need? Capacity, etc?</p><p>&nbsp;</p><p>Thanks,</p><p>-Matthew and Kassie</p>

 

[LovngRVlife]

You can wire an automotive high current relay as a switch. Hook 85 to power or ACC wire, 86 to GND, 87 to + of master battery, 30 to + of your slave battery. Then Ground negative pole of your slave battery. Don't forget to put a 15A inline fuse between the 85 and your power (or ACC) wire.&nbsp; The relay cut off the circuit when the engine is off and connect the main battery to the slave battery when the engine is on. <br />A sample of 80A relay<br />http://www.amazon.com/Power-Relay-Single-Double-Throw/dp/B001PNMBE4/ref=pd_cp_e_0<br /><br />

 

[akrvbob]

This is the one I use<br />http://www.amazon.com/Perko-8501DP-...ive&amp;ie=UTF8&amp;qid=1344438876&amp;sr=1-1<br /><br />You pay extra for marine stuff, but it is usually better quality. Chances are you can go to Walmart and buy one for much less in the auto section. Bob