Wiring in a Sterling Alternator to Battery Charger

[Poey50]

I've got myself confused about whether the leads from the A2B unit should go to the line side or load side of the switches on their respective engine or house circuits. The instructions make no mention of the switches but this simplified circuit diagram - found elsewhere - shows the unit wired in on the line side. Presumably this would leave it always on. Is that right?

 

[VicS]

The installation instructions also show fuses in the connections to the A2B unit

 

[Poey50]

The installation instructions also show fuses in the connections to the A2B unit

Yes, I'm all ready to put the fuses in - just need to work out which side of the switches to wire it in.

Instructions for the unit here ..

https://cdn.shopify.com/s/files/1/0658/7343/files/AB12130.pdf?477

 

[pvb]

I've got myself confused about whether the leads from the A2B unit should go to the line side or load side of the switches on their respective engine or house circuits. The instructions make no mention of the switches but this simplified circuit diagram - found elsewhere - shows the unit wired in on the line side. Presumably this would leave it always on. Is that right?

It's only on when the engine's on. If you wire it to the battery side of the switches, it'll still charge the batteries if someone turns the switch off! You must fuse it according to the instructions.

 

[Poey50]

It's only on when the engine's on. If you wire it to the battery side of the switches, it'll still charge the batteries if someone turns the switch off! You must fuse it according to the instructions.

Cool. Wiring to battery side of switches it is ... I won't forget the fuses. Thank you.

 

[Billows]

How would the charger be wired with the normal 1/2/off/both switch

 

[pvb]

How would the charger be wired with the normal 1/2/off/both switch

Direct to the batteries, or on the battery side of the switch.

 

[Billows]

I take it that the alternator is connected solely to the charger input that case

 

[pvb]

I take it that the alternator is connected solely to the charger input that case

What else would it be connected to? Follow the installation instructions carefully.

 

[VicS]

How would the charger be wired with the normal 1/2/off/both switch

IMO it would make sense to fully separate starting and domestic circuits replacing the 1,2,both,off switch with separate isolators and making the batteries dedicated starter and domestic batteries. That is after all the set up the Sterling AB chargers are designed to support, giving enhanced charging of the domestic battery and bog standard charging of the starter battery.

 

[Billows]

What else would it be connected to? Follow the installation instructions carefully.

Usually like this

 

[VicS]

What else would it be connected to? Follow the installation instructions carefully.

And wire it like this

 

[pvb]

View attachment 59792Usually like this

Not usually like that. The Sterling A-to-B charger has 2 separate isolated outputs; one is unboosted and is for the starter battery, one is boosted and is for the domestic bank.

 

[Billows]

View attachment 59792Usually like this

On my diagram you would remove the connection from alternator to starter, wire the alternator to input of the ab charger and connect the house output of the charger to R1 and the start output of the charger to R2 suitably fused

 

[pvb]

On my diagram you would remove the connection from alternator to starter, wire the alternator to input of the ab charger and connect the house output of the charger to R1 and the start output of the charger to R2 suitably fused

You could do that, but it would be much better to have 2 simple on/off switches.

 

[Poey50]

You could do that, but it would be much better to have 2 simple on/off switches.

Or better still a third on / off switch linking the two for 3 emergency options:
1. Combining both batteries
2. Starting engine with domestic battery
3. Running domestic circuits from engine battery

 

[neil1967]

Exactly what I have.

 

[FullCircle]

I also have my 25a Cristec battery charger going into the input side of the A2B. I also have separated battery switches

 

[VicS]

Or better still a third on / off switch linking the two for 3 emergency options:
1. Combining both batteries
2. Starting engine with domestic battery
3. Running domestic circuits from engine battery

If you fit a combining switch in combination with separate isolators fit it between the two circuits rather than between the two batteries as that gives you the option of using one battery for all purposes while leaving a dead battery isolated.

 

[Poey50]

If you fit a combining switch in combination with separate isolators fit it between the two circuits rather than between the two batteries as that gives you the option of using one battery for all purposes while leaving a dead battery isolated.

Yup .. definitely.