Adding starter battery to existing solar setup? Wiring spec question

PaulC70

PaulC70

Joined
May 8, 2021
Posts
1,778
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3,588
Location
Bedford, UK
Funster No
81,023
MH
Bailey Autograph792F
Exp
Since June 2021
Sorry all, I do hate electrics.
OK, so only had the motorhome (Bailey alliance se) for a few months and it's already got the 100w solar panel fitted and charging the leisure battery. However, I want to wire in the starter battery too just to keep it topped up.

Now, while I've been told that 1mm2 (1mm square) rated at 16.5amp is more than adequate, damn its thin! I mean the twin core is as thin as the existing wires going into the controller :unsure:

So, given that (after routing) the length of wire needed will be between 3 and 5 metres, and having googled and read about voltage loss on the chart here https://www.leadingedgepower.com/support/help-with-solar-panels/solar-cable-charts.html Im assuming I actually need 3mm2 wire and not the 1mm2 ? Can anyone shed any light on this before I go ahead?
 
Just add a battery master,they are easy to fit and cheap ,around £20. They allow a charge to the starter battery once your leisure batts are up to a particular charge level.allows a trickle charge to starter batter .
 
Two on Tour said:
First off, does your solar charge controller have a provision for charging a second battery ?
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Yes
Jimbohorlicks said:
Just add a battery master,they are easy to fit and cheap ,around £20. They allow a charge to the starter battery once your leisure batts are up to a particular charge level.allows a trickle charge to starter batter .
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Where have you found them at £20 as I can only see them at 60 plus?
 
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I think your biggest problem will be feeding the red and black cable to the starter battery but worth the effort.
I would recommend 2.5 mm minimum flex cables (20 amp) from the solar controller
 
Stealaway said:
I think your biggest problem will be feeding the red and black cable to the starter battery but worth the effort.
I would recommend 2.5 mm minimum flex cables (20 amp) from the solar controller
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yeah, to be honest now it's just being a pain trying to route it all, think im going to go with a battery master device instead, should be a lot less invasive fitting.
 
Two on Tour said:
I fitted a Battery Master a few years back and it works faultlessly, a great bit of fit and forget kit. (y)
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I echo that.
Be aware that a true Vanbitz Battery Master works differently from the cheaper ones off eBay. The cheaper ones only charge the van battery once the leisure battery is fully charged - typically 13.5+ volts. However you can't guarantee that the leisure battery will actually reach that value. The Vanbitz version will maintain the van battery at approx 0.8 volt less than the hab batteries at all times and will keep charging the van battery, even if the hab voltage drops below 13.5 volts.

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Revolvor said:
I echo that.
Be aware that a true Vanbitz Battery Master works differently from the cheaper ones off eBay. The cheaper ones only charge the van battery once the leisure battery is fully charged - typically 13.5+ volts. However you can't guarantee that the leisure battery will actually reach that value. The Vanbitz version will maintain the van battery at approx 0.8 volt less than the hab batteries at all times and will keep charging the van battery, even if the hab voltage drops below 13.5 volts.
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I did wonder about that I have to admit and possibly why the vanbitz one is over twice as expensive.

Is the one in the Fun shop linked above an actual vanbitz one though?
 
PaulC70 said:
I did wonder about that I have to admit and possibly why the vanbitz one is over twice as expensive.

Is the one in the Fun shop linked above an actual vanbitz one though?
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No, but it is much better for Funsters to buy one from the Motorhome Fun shop as it's cheaper, and we don't offer the 10% MHF discount when you order online from our shop. We are not a mail order business the Battery Master is the only thing that we bother to sell online and if we have a "Club Discount Code" all the Riff Raff like the Caravan Club and the Oiks all phone up and want to negotiate a membership discount for the "Panda Owners Club" and frankly I can't be arsed! There will only EVER be a members discount for FUN as I am a member and I love the forum!

As for more expensive, its is 100% waterproof, 100% vibration proof, if fitted correctly doesn't need fuses, and works faultlessly and isn't worried about the donor battery voltage unlike many others that will only work when the donor battery reaches XYZ voltage which often never happens in the Winter when you need it most!
 
eddievanbitz said:
No, but it is much better for Funsters to buy one from the Motorhome Fun shop as it's cheaper, and we don't offer the 10% MHF discount when you order online from our shop. We are not a mail order business the Battery Master is the only thing that we bother to sell online and if we have a "Club Discount Code" all the Riff Raff like the Caravan Club and the Oiks all phone up and want to negotiate a membership discount for the "Panda Owners Club" and frankly I can't be arsed! There will only EVER be a members discount for FUN as I am a member and I love the forum!

As for more expensive, its is 100% waterproof, 100% vibration proof, if fitted correctly doesn't need fuses, and works faultlessly and isn't worried about the donor battery voltage unlike many others that will only work when the donor battery reaches XYZ voltage which often never happens in the Winter when you need it most!
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Can I ask eddievanbitz are you open in December at all, as the more I think about it the more I want to get a strikeback and Growler fitted to my Bailey Alliance SE?

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PaulC70 said:
Now, while I've been told that 1mm2 (1mm square) rated at 16.5amp is more than adequate, damn its thin! I mean the twin core is as thin as the existing wires going into the controller :unsure:

So, given that (after routing) the length of wire needed will be between 3 and 5 metres, and having googled and read about voltage loss on the chart here https://www.leadingedgepower.com/support/help-with-solar-panels/solar-cable-charts.html Im assuming I actually need 3mm2 wire and not the 1mm2 ? Can anyone shed any light on this before I go ahead?
Click to expand...
My take on the original question - the chart says 3mm2 wire for 100W panel and 5m length. I would imagine you will be setting the starter battery charge to be much smaller than the leisure battery charge. Usually 90%/10% split. You would be sending 10% of the amps to the starter battery, so you will need only 10% of the cross-sectional area, ie 0.3mm. However there is a case for saying that no wire should be less than 1.5mm2, because it is not physically strong enough in a vibration-prone environment.

The other point about routing a wire all the way to the starter battery - it's not usually necessary, because there is likely to be a substantial starter battery wire located conveniently on the split charge relay, or the 12V distribution box. So you could connect to that. The solar controller will have all the appropriate diodes to ensure there is no unwanted back-flow of current.
 
eddievanbitz just emailed you re dates but stupidly forgot to say its a Peugeot cab, Bailey 76-2 2021 model. :banghead:

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I've tagged him so he will see it and in the original email have given all other details etc etc, by tagging him Eddie will be more than capable of putting 2 and 2 together, he's a sensible chap. As for a public forum, not sure I've given away any secrets that Im aware of :rolleyes:
 
PaulC70 said:
I've tagged him so he will see it and in the original email have given all other details etc etc, by tagging him Eddie will be more than capable of putting 2 and 2 together, he's a sensible chap. As for a public forum, not sure I've given away any secrets that Im aware of :rolleyes:
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It was more the fact that as he's a busy man, he may not see the post! :giggle:

Don't worry, your secrets are safe with us! :ROFLMAO:
 

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