Victron argo battery isolator for 3 batteries100a

[sigard]

Hi I’m just in the process of converting a welfare van to a camper, and not really up on the electrics, it has a /victron battery isolator 100a fitted with a bank of two batteries, what does this box do? When we finally get let loose! If we stay on site using the leisure batteries, will this unit stop the starter battery draining down?
The other thing is, one of the leisure batteries was no good, so when I replaced it I disconnected the starter battery, changed the bad battery and when connecting the starter battery inadvertently connected it to the Earth terminal and not the positive, now the little light on the isolator doesn’t come on, could I of damaged the isolator? Any help will be appreciated.

 

[Tombola]

the battery isolator allows 1 input from our altermatr and allows to charge 2 batteries independently. So in effect the 2 batteries can be 2 batteries and not combined to 1 "bank"

In general you want your batteries to be in 1 bank so you probably dont have any need for the isolator. The welfare van may have had 2 circuits operating independently or evan each seperate for redundancy protection.

Possibly not damaged the isolator but you may not be using it anyway and coud remove.
I cant say much else and better experts will be along about the short out , but there are other questions like do you have solar, are you going to be on hook up most time, to answer the "will the starter battery drain down" question.

 

[autorouter]

it has a /victron battery isolator 100a fitted with a bank of two batteries, what does this box do? When we finally get let loose! If we stay on site using the leisure batteries, will this unit stop the starter battery draining down?

Yes, that's what it's meant to do. It contains diodes, which are electrical one-way valves. Charge can go from the alternator to starter battery and leisure battery (and also to a third battery bank, but that probably is not used). However the charge can not back-flow from one battery to another. If the the leisure battery goes flat it won't drain the starter battery.

In reality it's not quite as simple as that. If the batteries are totally isolated from the alternator, the alternator control circuit will think there is no battery connected, so will not energise the alternator. There is a clever circuit and a couple of extra wires to get round this problem.

This is unusual in motorhomes, it's more common on boats I think. The more usual arrangement is to use a relay, which is an electrically operated switch. The starter battery is permanently connected to the alternator, so no start-up complications.

There is a low-power output called D+, from the alternator when it is running. This is used to trigger the relay, connecting the leisure battery to the starter battery while the alternator is running. When the engine stops, the alternator stops charging, the D+ goes back to zero, and the relay switches off. This disconnects the leisure battery from the starter battery when the engine stops. This relay is called a 'split charge relay'.

A big advantage of the split charge relay method is that the original vehicle alternator and starter battery wiring is not disturbed. The relay and leisure battery are add-ons.

 

[sigard]

Ok thanks, my main concern was flattening the starter battery, but by the sound of it,that can’t happen. I want to look into a split charger, I’m in Milton Keynes does anyone know of anyone that could fit it for me?

 

[autorouter]

There's a couple of other gadgets you should be aware of, although many motorhomes don't have them.

A battery-to-battery (B2B) charger charges the leisure battery from the alternator when the engine is running. It is a proper multistage charger, and can be used if the leisure batteries are a different type to the starter battery. It takes power from the alternator when the engine is running, and is often used just to boost the charging power to big leisure batteries. They are necessary in the latest motorhomes with smart alternators, which otherwise would only half-charge the leisure batteries.

A battery maintainer is the opposite, it trickle-charges the starter battery from the leisure battery. There are different types.

One type has a voltage threshold, and won't charge the starter battery unless the leisure battery is being actively charged (mains charger, solar etc). Example: CSB2

Another type senses the voltage difference, and only charges the starter battery when its voltage drops a fixed voltage below the leisure battery. Example: BatteryMaster

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[BasherBaz]

I take it the van had a wheelchair lift of similar on the back hence the need for the auxiliary batteries and isolator.
Try Youngs conversions for the battery charger circuit. I believe they are still in Milton Keynes.