# Zig DCU/3 what connections?



## 104817 (May 29, 2007)

Hi all

I have a self-build van with a ZIG CP800 control/distribution panel and a DCU/3 charger/power supply.

The CP800 does what it says on the tin: - takes 12v in from the van and leisure batteries and via a bank of switches, supplies power to lights, fridge igniter, pump etc. No problems (that I know of!) there then.

My issue is with the DCU/3. THe DCU/3 has 5 outputs on the rear:

3 earth/ground/negative connections and two other connections. 

Of the latter two connections, one is a +12v 7.5 Amp (max) supply from pin 1 of the DCU and goes to the leisure battery to charge it whilst hooked up and the other (pin 2) is to power 'accesories' 

My main question (I have a few!) is why have this separate +12v supply to the battery side of the system? Is it so that when on hook up, 12v power only comes from the DCU and not from the batteries at all? On my van it is wired in somehow and if I disconnect it (it appears to go to the 'Leisure battery in' terminal on the CP800) then the whole 12v leisure side goes off, even if pin 1 remains connected to the batteries. As long as pin 2 is connected, even if the DCU is turned off, the 12v leisure system works. I really want to rewire a single charger/power unit in place of the DCU as I think it's a little underpowered (the 7.5 Amps is max, I think 4 Amps is its continuous output) but I need to understand why the second output exists and how it's wired into my van. I can look at the wiring but the second output confuses me.

Thanks and regards

Phil


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## peedee (May 10, 2005)

Have you had a look at the >Zig web site<  a DCU/3 is not listed there but you could try contacting them? I have ZIG X-7 which has 5 outputs and the circuit diagram shows a "suggested" wiring.

1- goes to the leisure battery positive and supplies the van
2- goes to the engine battery positive
3 -goes to the engine battery negative via a fuse and relay
4 -goes to the leisure battery negative
5 - unused

2 and 3 are used to charge the leisure battery when the engine is running.

Does that help.

peedee


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## 104817 (May 29, 2007)

Hi Peedee

Thanks for your reply. I haven't contacted Zig as yet. I have the DCU manual but it doesn't really explain why they've provided this 12v/5A smoothed supply, only to say it is

'to power the accessories, thus allowing a permanent hook up situation for the duration of a holiday without worrying about the battery'

Which sounds like it completely bypasses the leisure battery system when it (the DCU 3) is turned on, even though the leisure battery part of the system has a 7.5A supply available plus a hefty battery to draw from. This accessory output of 5A isn't a huge amount of 12v DC though - a couple of decent 12v strip lights will take close to 1A each and if you have a CD player (another 1A possibly) you've probably only 40% capacity left.

As I don't wish to use the starter battery to power the habitation area I may just disconnect that and put a 10A supply in its place. These usually benefit from having a battery in circuit too however, to provide smoothing.

The joys of electrics!!!

Phil


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