Ignition relay for deep cycle to alternator?

[patrickkidd]

Hello!

I got an old FWC Ranger 2 and am trying to sort out how I want to wire the fee cycle circuit it to the alternator for charging. There is no existing circuitry.

I recall in my bandaging there was a relay that connected the deep cycle to the alternator whenever the engine was running. This prevented the starter batter from ever draining. Is this the way people usually rig their tuck campers too? Or are there better options? I’ll be adding a moderate solar circuit for my usage requirements.

-Patrick

 

[Vic Harder]

Current thinking (pun intended) is to use a Blue Sea ML7622 ACR to do the switching. I used 2g welding cable to go from:
Truck Battery --> Blue Sea 100A 285 series breaker --> cables --> Anderson PowerPole connectors --> cable --> another 100A breaker --> ACR --> short cable to camper batteries.

The 2g might be overkill, 4g seems to work for others. I have seen 80A going over those wires to my camper batteries during bulk charging.

 

[klahanie]

Yep. old school. What I used on my previous truck for many years, using a starter solenoid like below. Can buy at auto parts, RV, online.

Continuous duty is better/might last longer.

Connecting pos supply from the truck battery might be easier than from the alternator.

Connect charge supply to one large side terminal. Feed aux battery from other large side terminal. Small terminal is for trigger coil, connect to ignition hot. On model shown trigger coil grounds thru body, some models have additional small ground terminal.

Some variations: use a latching solenoid, add dash mounted switch to ignition hot, source ignition hot from alternator if alternator is controlled with an ignition delay, keep jumper wire handy (clipped on nearby) for emergency engine start.

Note this method does not prioritize battery bank charging. Repeated short driving trips may not charge the truck battery sufficiently for subsequent engine starting so some form of override may be desired. YMMV

 

[ntsqd]

I've had the constant duty solenoid charging system in the past. The ACR is a much better way to go.

I wired ours a bit differently than Vic. Instead of "> another 100A breaker --> ACR --> Battery" I wired ours to be like this: "> ACR -->another 100A breaker --> Battery" though I used 80A breakers instead of 100's. The reason for the difference is subtle. Our Phoenix has no master electrical shut-off switch. So this way the breaker serves that purpose too.

 

[cwdtmmrs]

Ok, I have been running a constant duty relay triggerd off of the accessory circuit to charge my camper battery for 11 years now (same yellow top Optima) without any problems. Why is the ACR better and why should I switch?

cwd

 

[ntsqd]

I wouldn't change a thing if the system is doing exactly what you need it to do. If it isn't then consider this:

Our VSR senses when either battery is topped off and still under charge. At that point it closes and allows whatever is doing the charging to charge the other set of batteries.

1) Starting the engine. VSR doesn't close until the alternator has brought the starting batteries back up.

2) Sitting in our yard. VSR closes when the solar has brought the camper batteries up and allows it to charge the starting batteries.

Opens when the charging voltage goes away for any reason.

 

[cwdtmmrs]

Thank you. Which VSR are you using?

 

[ntsqd]

BEP Marine
http://www.bepmarine.com/en/710-140a

 

[patrickkidd]

BEP Marine
http://www.bepmarine.com/en/710-140a

That looks like a really great option, particularly with their optional switch.

 

[ntsqd]

I dislike switches like that. At some point I am guaranteed to leave it in the most detrimental setting and forget about it until it is too late.

 

[patrickkidd]

I found one of those BEP switches for 40 bucks on eBay. We’ll see how it goes.

 

[ntsqd]

Is it a single sense or a dual sense model? The older units were single sense, then they offered both, and now they only offer the dual sense.

If it is a single sense then polarity i.e. which terminal the house battery bank and which terminal the starting battery bank are attached to will matter. Hook it up wrong and the expected charging source won't be able to charge the opposite battery bank.