Making sense of 240v/12v charging and rigging the van up.

[poshbuggers]

I need a bit of advice.

My old ex-ambulance has cables for 3 batteries and a split charge relay (like a Westy) hooked up into the fusebox. I'm not sure how the 2 other batteries are being charged or whether they are hooked into the main circuit.

Now what I want to do is use a 240v charger from the hookup to charge the 3 batteries when on-site. The main battery (in the engine bay diesel location) is to be the starter battery and a pair of auxiliary batteries in the cab boxes for leisure use only. I don't want the leisure systems linked to the starter circuit at all to protect the starting battery from drain. Also separating the starter battery allows me to immobilise it.

The charger is an intelligent charger that can handle 3 batteries of varying types and is made by Hi-Tec for the marine industry. Here is the booklet to go with it.

http://www2.kegel.de/tecsup/pdf/charger ... 00-use.pdf

In summary from the 240v I want to run the charger unit and 2 mains sockets only. On the 12v side I want to run a bank of LED lights, 12v TV/DVD unit and Waeco B40 hybrid fridge when not hooked up/travelling and charger sockets for the Ipad/mobiles.

I'm good with wiring but could do with some help splitting these circuits, particularly the 240v from hookup to consumer unit. Should the charger be run from the consumer unit or alongside and what rating would the fuse be for it if so? I usually run a 16A/6A setup but what do I need for the charger and sockets now?

Thanks in advance.

[CJH]

Do you know anything more about the charger's three connections? Based on what I've found out about other chargers with multiple outputs I believe the available current will be shared between them (and they'll share the same charging profile), so if yours is the 25A model then those 25 amps will be shared, rather than it being 25A per output. So 25A at 12V is just 1.25A at 240V.

Assuming you also want to run the compressor side of the fridge when on hookup, it seems to use 65W on average, so at 240V that's only a quarter of an amp.

Even allowing for less than 100% efficiency, and greater draw from the fridge at peak loads, you could quite easily run both of those from the 6A circuit breaker on a 16A/6A consumer unit I'd have thought.

[poshbuggers]

I couldn't find any reference in the linked booklet to the charge rates when multiple batteries are connected to ascertain anything but had a look inside and the three + positive connectors have individual capacitors (see the link). I'm not sure that means much.

https://www.facebook.com/photo.php?fbid ... da03f65bba

[CJH]

I couldn't see anything in the booklet either. Is there one set of charging profile switches per output, or is there one set that's common to all three outputs?

Even if your charger is capable of 25A per output, that would still only be 3.75A in total at 240V, so you'd still fit that and the fridge on a 6A circuit breaker.

[poshbuggers]

It's just a pair of dip switches for all three connections so they share the profile.

I can't see me running anything more demanding than a laptop charger to be honest which I think is input 1.6A, 65W power at 3.34A output.

I guess I could run a RCD for the charger and one for sockets just to be tidy.

[poshbuggers]

Here is my circuit so far (laugh away, I drew it quickly ).

https://www.facebook.com/photo.php?fbid ... 4670248094

The charging unit has one negative terminal for all three batteries. I assume I can earth each battery to the body and tag the unit earth to the body on it's own?

I haven't added lighting/12v power sockets and entertainment yet. I'm not sure whether to split them up into different halves of a fuseboard or how to put the two leisure batteries on a split charging relay.

[CJH]

Yep - 6A for the fridge and charger, 16A for the internal 3-pin sockets. That's (almost) what Zig recommended for the panel in my van.