Battery Charging

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On our Elddis CV40 the Truma dual solar controller is only connected to the leisure battery, I have fitted another matching Yuasa 95 amp AGM battery to give me a bit extra. The 100 watt solar panel is seeming to cope keeping them charged. There is another output on the controller which the manual says is Battery2 (starter battery) which isn't connected. In fact the solar charging & mains charging only charge the leisure battery, the problem I have is if I don't run the engine the engine battery will slowly discharge when not being used. I was wondering that if I fitted a cable I can disconnect from the Battery2 output to the engine battery would this be a problem, would it matter if the engine battery isn't an AGM type (the controller is set for AGM. On the controller it can be set for how the power is split between the 2 batteries so I was thinking of having 90% to the leisure batteries & 10% to the engine battery. I can easily make a cable that I could unplug when I'm using the van on a regular basis, I'm only thinking of the times where the van might be left standing for a while.
 
I take it that you are charging both of your leisure batteries together in parallel from the solar controller?
In that case you could add the van battery permanently as Battery 2 as you describe.
As your leisure batteries are identical and discharging together the charger will probably operate as expected in terms of coming to float etc.
It's really handy to keep the van battery topped up to run alarms etc when parked up for a long time.
 
Why not get one of those one way cables that run from cigarette lighter to cigarette, that'll keep the starter battery at virtually the same voltage as the leisure one.
I forget what they're called but I had one for years. It became redundant when I upgraded my van to one that charged both batteries on hookup.
 
Cigarette lighter link only an easy solution if van van socket is unswitched - and does need disconnecting to save van battery when drawing hab power.
Need to be quick on the eBay device (whatever it is) No deal Brexit will stop easy purchases from Europe!
 
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Just take the wire from unit to second starter battery with a fuse at the end,or if you want to connect all together for an emergency start then this picture with a relay will work as thats what i have.
200ah relay.png
 
Thanks for the replies, the 2 leisure batteries are connected in parallel. My only concern was the engine battery being a different type to the AGM ones. I am guessing that the 2 outputs on the dual controller are independent of each other, but the battery type can only be set for one type. Reading the manual regarding what percentage of the charge goes to which battery, if it only detects one battry it sends it the full charge. My idea of using the 2nd out with a temporary cable is for the odd times I'm not planning on using it for a while, & to compensate for the drain with things like the alarm. Most times it would be charged by the engine.
 
Yes - connect van to Batt2 and set at 10% to ensure priority to Leisure.
As you say draw will be minimal after driving and when at home both sets will be kept topped up.
I've had this charger with a different brand label for a few years and it does a great job.
 
Alternatively, fit a Battery Master between the two. That way all charge from your solar goes to the leisures, and the Battery Master transfers 1.1a of charge to the vehicle battery 24/7 - to keep it topped up.
 
When van is full 100% goes to Leisure, but if it does need charge max flow is 10% or nominal 10w which is less than 1A.
So no need to purchase any more kit - just run a decent flex from charger to van battery.
 
Interesting bit of kit.
I was thinking about mppt charger for my leisure battery but most I've seen only do one battery. So this is worth thinking about as an alternative to a separate small panel to just do the van.
 
Interesting bit of kit.
I was thinking about mppt charger for my leisure battery but most I've seen only do one battery. So this is worth thinking about as an alternative to a separate small panel to just do the van.
By the time you add up price and time to do above it is miles better just to fit the above solar regulator,it gives one amp to starter battery and the rest to less batts.
 
Agreed - I just need to decide whether I need mppt.
OP is happy with PWM on Leisure batteries so only minimal cost-effort to include top up for starter, with potential for boost if it did get really low such as leaving lights on.
 
Connected the engine battery to battery 2 output on the Truma regulator, I fitted a cigarette lighter socket to the regulator. I had already fitted a fused socket wired direct to the battery. I had a lead which was a battery analyser/charger cable which had cigarette lighter plugs on each end. When plugged in is charging both batteries. I have the regulator set for 90% to leisure battery with 10% to engine battery, I read the info on the regulator which says once one battery is charged it then directs 100% to the other battery. When I checked this afternoon the lights on the controller showed leisure batteries fully charged & the engine battery was showing 13 volts (this later dropped to 12.5 volts when not charging) so everything seems ok. I am happy just to have it like this for times I;m not using the van for a while. Thanks for all the replies.
 

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