Solar to Battery Wire Size

[Kontiki]

Finally getting round to wiring engine battery to Truma dual charge controller. What size of wire do I need, solar panel is 100 watts, controller is 10 amps, engine battery is 90 amps. Intend to have controller set at 90% leisure 10% to engine. At the moment I rigged up a temporary wire setup which I can connect to keep battery topped up if we aren't using the van for a while. Figured a route to hard wire it so need to buy some cable about 8 metres, ideally as small as possible to be able to route it through.

 

[wildebus]

so battery is a fair way from the controller?
when you say 8 Metres, to clarify... is that an 8 Metre cable run? or is it a 4M run and you are including both +ve and -ve? (would make a difference to cable gauge suggestion).
If you have the option, moving the controller to be closer to the battery and extending the Panel -Controller wiring would actually be slightly more efficient in performance.

 

[wildebus]

You should be good with this

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or

5m 2.5mm 2 CORE FLAT TWIN 12V RED BLACK ELECTRICAL CAR AUTOMOTIVE CABLE WIRE | eBay

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if it is the 4M run, this cable would work fine as well but I would try and stick with the 2.5mm if possible.

5m 1.5mm AUTOMOTIVE 12V 24V STRANDED 2 CORE FLAT TWIN THIN WALL RED/BLACK WIRE | eBay

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[Kontiki]

Roughly measuring it as I have to route it through the backs of cupboards I estimated about 6 to 8 metres. The van is 6 metres long with the controller in the top corner by the rear doors, van is a Ducato so battery under floor at front. Temporary cable is keeping battery topped up, not sure of size but doesn't look that heavy.

 

[wildebus]

ah, sorry. I was not picking up that this is for the auxilary/starter battery connection.
So ignore comment on relocating controller
I would probably go with the 1.5mm cable for that purpose if you want as slim as possible. If you have a close chassis ground you can use, you could use that to save running a cable pair and just run a single +ve instead.
Also, if you have any connection anywhere that is provided by the starter battery, you can use that - you don't have to run all the way to the battery if there is a handier place.

 

[wildebus]

PS. given the length of cable run, I would recommend you fuse it both ends (as both ends are a source of power). Just a couple of basic fuse holders would do the job.

 

[Kontiki]

Not sure I can find somewhere easily for earth connection near controller. Not sure what size the wire i had was, that is just over 5 metres but that is through the van, it will probably be about 6.5 metres but don't want to end up being a bit short. Got some blade fuse holders due to be delivered this week.

 

[wildebus]

better a metre or two too long than 10cm too short (it can be very frustrating, especially with heavy cable )

 

[Kontiki]

Ordered thanks for your help.