Camper Electrician

Could anybody recommend one in Manchester/North West ?

Have a few little checks and jobs I need to sort out.

SMC in Newark are quite good, may be too far from you though.

You can always ask questions here!!

Along those same lines I would love a wiring diagram for the Cruising Cabin if that might actually exist.

Amongst other things, what I am trying to do is have a twin battery system where when mobile, the alternator will charge the primary battery until full, then automatically switch to the secondary.

I also have a CTEK MX5 intelligent charger. I want this to be powered by the EHU and behave as above when in the garage at home or plugged in on site. I have installed an additional single 240v socket in the cupboard to power this.

I'm reading a lot about relays, VSRs and SCRs and getting a bit confused. Not even sure if what I want to achieve is possible.

On top of the above I have something draining the battery which I need to get to the bottom of and a few niggly little things I have tried and failed to sort such as a failed courtesy light and the need to install a couple of 12v USB sockets.

None of these are particularly huge jobs, but auto-electrics always seems a bit of a dark art to me. I would be happier paying a pro, as long as I feel well informed enough to not get done.

I am holding off installing any more electrical accessories until I feel I have a more robust supply.

This is very informative, but poses more questions than it answers. Especially in relation to VSR's which seem the closest solution.

charging options...

Ok so first I'd advise you to buy one of these:

UNI-T UT210E Current clamp multimeter. Don't get a cheaper one, you need this one as it does DC currents and is very very good. This will immediately allow you to tell how much current is flowing in a wire so you can track down current drains and usage easily.

Does the MX5 not come with suggested wiring diagrams to pick and follow? I'd expect CTEK to, even if online.
As for charging a domestic battery - do you mean having two domestic batteries?

12V auto-electrics are only complex because we have this on/off grid backup-power thing going on

Edit: Get the UNI-T UT210E, not the A, B C or D models, it must be the E model.

GPW wrote:

Ok so first I'd advise you to buy one of these:

UNI-T UT210A Current clamp multimeter. Don't get a cheaper one, you need this one as it does DC currents and is very very good. This will immediately allow you to tell how much current is flowing in a wire so you can track down current drains and usage easily.

Does the MX5 not come with suggested wiring diagrams to pick and follow? I'd expect CTEK to, even if online.
As for charging a domestic battery - do you mean having two domestic batteries?

12V auto-electrics are only complex because we have this on/off grid backup-power thing going on

Checked out that multimeter and it seems affordable enough (about £15).

However, it's one thing having the tools and a different thing altogether knowing how to use them.

The van already has a pretty decent 240v setup however, I tend to do a fair bit of wildcamping so the only only method for charging devices is via the existing and additional USB ports. I dont fancy finding myself unable to start the van after a few days in the middle of nowhere without driving.

I installed a new cranking battery last summer, but using the CTEK have since recovered the old one. So the plan is to use that in the interim. Eventually maybe replacing with a gel.

The CTEK guidance doesn't extend beyond conventional installs.

No worries, the multimeter is easy to learn, set it to 2A or 20A, press the 'DC' button and then clamp the little clamp over the wire to read off the current going through it.

Current is in Amps, Battery size is in Ah (Essentially the number of hours at 1 amp draw), so you you detect a 1A current from a 80Ah battery, it will last 80 hours. Or 40 (half) if you want the battery to last more than a year...

I see so you have 1 battery in the van and want to add a 2nd. The 'while driving' charging of this is done simply by a split charge auto-sensing relay:
https://www.ebay.co.uk/itm/100-Amp-Split-Charge-Relay-Voltage-Sensing-Control-Unit-With-Manual-Switching/222707399391

Which IIRC comes with wiring instructions... but you do need to use 10mm2 wire and a proper fuse at each end if you don't want it all to catch fire .

Sorry I did not realise the MX5 is a simple charger, it will realistically only charge one battery at a time.

My system consists of a start battery 1 house battery 130amp hr good quality split charge relay, 240v supply panel found in caravans, and sockets with 12v charging to house battery, all with fuses in appropriate places + 130 watt solar pannel on roof with 30 amp controller. On the consumption side I have 3 way fridge water pump LED lights through out TV and sat receiver + usb sockets for phones on a panel with voltage readout, interesting to watch TV and Voltage going up and down as solar controller cuts in and out 13.5v to 14.9 nice to now the panel is keeping up with consumption. As yet with many weeks wild camping have not run out of power. Must add we have a diesel heater that is heavy on electric and has to be limited in use, as yet no problems at all, my motto is keep it simple and it will be easy.

GPW wrote:

Which IIRC comes with wiring instructions... but you do need to use 10mm2 wire and a proper fuse at each end if you don't want it all to catch fire .

Sorry I did not realise the MX5 is a simple charger, it will realistically only charge one battery at a time.

It comes with a basic wiring diagram.....




However, where is the alternator in that set up ? Is it connected to the +ve on both batteries ?

The CTEK will only charge one battery, it simply replaces the alternator when the EHU is applied when stationary. The question is can I use the same SCR set-up for both charging setups, or will I have to duplicate the components ?

That is my setup with alternator going to primary battery.

The primary battery is charged by the alternator as usual as noted, nothing needs to be touched there, don't worry about the primary battery: it's looks after itself.

The domestic or secondary battery will - with that circuit - be charged as you drive.
When on EHU simply connect your Ctek to the domestic battery only.

That's it!

GPW wrote:

Ok so first I'd advise you to buy one of these:

UNI-T UT210A Current clamp multimeter. Don't get a cheaper one, you need this one as it does DC currents and is very very good. This will immediately allow you to tell how much current is flowing in a wire so you can track down current drains and usage easily.

Just looking at these clamp multimeters again and its a minefield on eBay. Most sellers are showing multiple types for the same listing and are very sketchy with the precise specification. So you have no idea what you might receive and with a return address in the far east it's all very messy and potentially costly.

YouTube videos seem to imply that its the 210E I would need for measuring voltage,

eBay has really gone down hill.  I'd go to Amazon.  Here's one for under £20

https://www.amazon.co.uk/Digital-Current-Voltage-Capacitance-Multimeter/dp/B07L256G9K/ref=sr_1_fkmr0_1?keywords=UNI-T+UT210A&qid=1558095465&s=industrial&sr=8-1-fkmr0

Does this not imply that the "A" model wont do voltage ?

weird, that's what it's looking like. For the extra £ I'd get the 'E'

You want the one with the DC current capability on it, so the E is the one you want, just checked and mine id the E, I'll edit my post to reflect that!

GPW wrote:

You want the one with the DC current capability on it, so the E is the one you want, just checked and mine id the E, I'll edit my post to reflect that!

"E" duly ordered.

.... (well it is a Friday night )

I think I need one of those too. Gets pretty old running a lead 10 feet to check continuity.