dual battery solar controller question.

sydnsue

sydnsue

Full Member

Messages
260
I am considering replacing my solar controller with a dual battery type. How do I connect the vehicle battery to the controller? I am assuming the on board charger is only for the leisure batteries so there will be no vehicle battery cables in the vicinity. The vehicle battery is located under the cab floor while the existing solar controller is almost at the back of the motorhome.
Is there anything else to consider? For instance, when the engine is running, the vehicle battery is being charged by the alternator but it is also still connected to the solar via the new controller. Is that ok or am I over thinking this?
 
You need to find a 12V connection to the starter battery that is always live (so not only live when ignition on or something else switched on).
Where this is best to find varies depending on the Motorhomes original electrics, but a good place can be the input to a B2B Charger or split charge relay. Or if you have something like a Sargent unit or an EBL say, there will be a starter battery +VE coming into the unit you could tap into.
The current the solar will supply to the starter battery will be very small so chances are any cable you find will be suitable enough but you should connect to the Solar controller via a fuse (5A say) close to it to be safe.

If there is nothing close and routing a cable is awkward (routing through new cables in a factory built Motorhome is possibly one of the most awkward jobs going), then ditching the dual battery controller idea and getting a stand-alone trickle charger (such as a Battery Master or an AMT12) might be a better idea, especially as you can fit that anywhere where you can find +VE from Starter and +VE from Leisure batteries close to each other already, such as where a B2B is installed.
 
sydnsue said:
I am considering replacing my solar controller with a dual battery type. How do I connect the vehicle battery to the controller? I am assuming the on board charger is only for the leisure batteries so there will be no vehicle battery cables in the vicinity. The vehicle battery is located under the cab floor while the existing solar controller is almost at the back of the motorhome.
Is there anything else to consider? For instance, when the engine is running, the vehicle battery is being charged by the alternator but it is also still connected to the solar via the new controller. Is that ok or am I over thinking this?
Click to expand...
We had an AMT 12 Trickle Charger fitted 16 days ago, as Wildebus suggests; there is a 'manual override' function where the supplied wiring can be connected to Switch 2 on the AMT, to force the Leisure Battery ['LB'] to pulse up to 3A to the Starter Battery ['SB'] for 9 seconds, then a 1 second break, then repeat. This keeps our SB in tip top condition, especially for the morning engine starts, and allows the LB to recharge when the Solar is getting the benefit of the Winter Sun; essentially, the LB plays' catch up', having boosted the SB earlier in the day. I love it, being spared the faff of the morning multimeter check after an ECU failure in mid November

Steve
 
I think designed and manufactured in the UK, I won't be doing the full install myself, just the panel, running cables and mounting the controller, I'm really bad with written instructions, I wonder if there is an install video, I much prefer those.
Checked and there isn't one :( :(
 
There are various ways of ensuring both VB and LB remain charged.

I have a VanBitz 'Battery Master' that is a simple fit and forget solution. At £70 I felt it good value as it's tiny, tucked out of sight, and links to my solar panel.
 
All these replies (thank you everyone) have me concerned. The dual controllers I am looking at on Amazon are around £30 which is why I thought it would be worth doing. All your replies are pointing towards 3 to 5 times that cost. Am I missing something? The ones I was considering are 20A (which gives me a reserve for the future) and the ratio between the 2 batteries is adjustable which seems a good idea.
 
HurricaneSmith said:
There are various ways of ensuring both VB and LB remain charged.

I have a VanBitz 'Battery Master' that is a simple fit and forget solution. At £70 I felt it good value as it's tiny, tucked out of sight, and links to my solar panel.
Click to expand...
Remember .... the "Battery Master" is only suitable for Lead Acid Batteries. It should not be used when a Lithium Battery (or a Lead/Lithium Hybrid) is installed. The same is true for all trickle chargers on the market EXCEPT, as far as I am aware, the only Battery Trickle/Maintainer that DOES work with Lithium, which is the Ablemail AMT12-2. This unit is programmable to work with Lead, with Lithium and also for vehicles that are fitted with either Smart or Standard Alternators (you select one of 8 pre-sert programs to suit your own vehicles configuration and requirements).
More info here - https://www.wildebus.com/product/ablemail-amt-12-battery-maintainer/ (link is to my own website - an internet search will find alternative sources). And FWIW, from me the AMT12-2 AND the cables are under £70 posted ;)
 
sydnsue said:
All these replies (thank you everyone) have me concerned. The dual controllers I am looking at on Amazon are around £30 which is why I thought it would be worth doing. All your replies are pointing towards 3 to 5 times that cost. Am I missing something? The ones I was considering are 20A (which gives me a reserve for the future) and the ratio between the 2 batteries is adjustable which seems a good idea.
Click to expand...
You will be missing something ... around 30% of the harvesting. The ones people are linking to will be the MPPT controllers which are far superior to the cheap PWM controllers.
The feature you mention about adjusting the ratio is a nice concept but in reality, will you ever be changing it? unlikely.
 
I'm wondering what be the best route from the controller in the rear of the van to the starter battery on a 07 and later Ducato.
 
sydnsue said:
All these replies (thank you everyone) have me concerned. The dual controllers I am looking at on Amazon are around £30 which is why I thought it would be worth doing. All your replies are pointing towards 3 to 5 times that cost. Am I missing something? The ones I was considering are 20A (which gives me a reserve for the future) and the ratio between the 2 batteries is adjustable which seems a good idea.
Click to expand...
The VanBitz Battery Relay that was fitted when we bought the M/Home in Apr 21 was removed on 4th Jan, because it didn't cope with the Lithium Battery. If it's any use to you, it's available for £30 inc postage

Steve
 
Mine was a mppt for 60 quid I'd you need details
 
I have had one of these for two years or so now and it seems to do the job. As David said, you will probably find a point near the onboard charger where you can have easy access to +ve connections for both batteries. This how mine is fitted because I never required the ''start assist'' that can be done to get a bit of a kick from the leisure batteries if need be. Just a 20A fuse in each of the +ve connections on mine for a bit of protection.


Cheers

H
 
There are some good videos on you tube about so called chargers sold as mppt .
That are not ...
Do your research check out your chosen one..
 
You must log in or register to reply here.

Users who viewed this discussion (Total:0)

Back
Top