dual battery solar controller question.

wildebus said:
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.,.....,...,..,.
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Thanks for adding that qualifier David, and of course you are absolutely correct.

My setup is a Lead Acid battery, as are the vast majority of motorhomers, as we do not need Lithium.

I'm of an age when our first unit had a Porta potty for a loo and a gas mantle for lighting. Somehow, I miss the simplicity of those days.
 
Well I felt ignorant before but this has totally floored me. Suggestions that I need solar after reading this will send me running to the hills
 
Personally I would say stick to a decent Mppt controller for the Aux batteries and make a diy charger for the chassis battery all it needs is a diode a fuse and a pic device to limit max current e,g a light bulb all wired in series.

Diode and fuse should be rated above the current the bulb could draw e.g a 55w halogen bulb would be circa 5A although in practice unless the target battery was virtually a dead short full current would never be drawn.

In typical use target battery will trickle charge up until it is around 0.7v lower than the source at which point zero current will be flowing.


Votronic sell one that pretty much works as above.
Google:

Votronic 3065 Stand By-Charger 12V - Battery Master​

 
There are no dual MPPT solar controllers on the market, but there are a few that charge the hab battery using MPPT and trickle-charge the engine battery in an unregulated way.

Any solar controller under £30, dual or not, is not going to be an MPPT one, though you can buy PWM ones with MPPT written on them.
If you're not sure whether MPPT is worth paying for, the answer is that it is.

What is far less clear is why you need to charge your engine battery from the solar panel. Motorhomes have solar panels to replace power used by the habitation systems. The engine battery shouldn't be used. A motorhome engine battery has no more load on it than the base vehicle has when it's a van.

If your starter battery is running flat, that's a fault that should be fixed. A solar charger won't fix it: it'll just hide the symptoms. If the battery isn't running flat, why add a solar charger?
 
Geek said:
There are no dual MPPT solar controllers on the market, but there are a few that charge the hab battery using MPPT and trickle-charge the engine battery in an unregulated way.

Any solar controller under £30, dual or not, is not going to be an MPPT one, though you can buy PWM ones with MPPT written on them.
If you're not sure whether MPPT is worth paying for, the answer is that it is.

What is far less clear is why you need to charge your engine battery from the solar panel. Motorhomes have solar panels to replace power used by the habitation systems. The engine battery shouldn't be used. A motorhome engine battery has no more load on it than the base vehicle has when it's a van.

If your starter battery is running flat, that's a fault that should be fixed. A solar charger won't fix it: it'll just hide the symptoms. If the battery isn't running flat, why add a solar charger?
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Parasitic drain from Alarms/Multimedia Units/Central locking, natural self discharge of starter battery etc. It's a bit late when the flat battery has taken out the ECU and the fault is not repairable, as I know to my considerable cost. In my case, there was also a reverse feed from Starter Battery to Leisure Battery dating back to 2016 when the Selling Dealer cross wired the rear camera and the Pioneer, but that has been traced and corrected now

The AMT 12, with the imminent addition of an On/Off switch to control the Switch 2 Boost Charge facility via David at Wildebus, gives me piece of mind day to day, and the back up of a power boost to allow me to stay off grid for longer; I am also limited to on street parking, and the AMT 12 transfer of power to the Starter Battery avoids the potential trip hazard of extension lead cables over the public footpath. It works for me, and that is really all that matters; we each make our own choices and live with the consequences

Steve
 
andromeda said:
Well none of the technical talk is selling that concept. I'm getting simpler with age. Flick a switch me and it either works or doesn't. If it doesn't work ask someone who knows.
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I usually ask someone who thinks they know ... And then the fun begins :rolleyes: That's the point at which I discover that 'expert' is really 2 words 'ex', as in 'was'; and 'spurt' as in 'drip' ...:D And he still knows more than I do!

Steve
 
Reverse feed... As I said, a fault that should be fixed, not hidden.

The parasitic drain from the ECU is normal for a van. The engine battery is supposed to cope with that. Alarm? If not the standard vehicle maker's install, it ought to be on the hab bank.
And if the battery is defective, solar really isn't the solution.

Yes, it's up to people to choose what they want to install, but we should not promote the myth that it's necessary, or even a good idea, to routinely charge the engine battery from solar.

FWIW, my motorhome's engine battery is currently being charged from solar, but that's because there's a spare solar charge system where it is parked and the battery is almost ten years old. I don't want to replace that until the pandemic restrictions are gone.
 
Geek said:
Reverse feed... As I said, a fault that should be fixed, not hidden.

The parasitic drain from the ECU is normal for a van. The engine battery is supposed to cope with that. Alarm? If not the standard vehicle maker's install, it ought to be on the hab bank.
And if the battery is defective, solar really isn't the solution.

Yes, it's up to people to choose what they want to install, but we should not promote the myth that it's necessary, or even a good idea, to routinely charge the engine battery from solar.

FWIW, my motorhome's engine battery is currently being charged from solar, but that's because there's a spare solar charge system where it is parked and the battery is almost ten years old. I don't want to replace that until the pandemic restrictions are gone.
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The reverse feed was traced, and the starter battery was replaced with a 3rd new one in 4 weeks when the ECU was replaced. The parasitic drain is seen by Dealers and Owners as just part of the process, especially the Pioneer system, and I know a couple of M/Home owners with quite new Vans that have suffered from Starter Battery drain, and the AMT 12 has provided a simple solution

Steve
 
marchie said:
I usually ask someone who thinks they know ... And then the fun begins :rolleyes: That's the point at which I discover that 'expert' is really 2 words 'ex', as in 'was'; and 'spurt' as in 'drip' ...:D And he still knows more than I do!

Steve
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Oh yes as a female driver I have met many. Best examples were back in the 80's when we could still get a wheel off without a garage being needed or fill with water without the RAC. The amount of 'help' from people who would have happily put water in the brake fluid was frightening.
 
Geek said:
There are no dual MPPT solar controllers on the market, but there are a few that charge the hab battery using MPPT and trickle-charge the engine battery in an unregulated way.

Any solar controller under £30, dual or not, is not going to be an MPPT one, though you can buy PWM ones with MPPT written on them.
If you're not sure whether MPPT is worth paying for, the answer is that it is.

What is far less clear is why you need to charge your engine battery from the solar panel. Motorhomes have solar panels to replace power used by the habitation systems. The engine battery shouldn't be used. A motorhome engine battery has no more load on it than the base vehicle has when it's a van.

If your starter battery is running flat, that's a fault that should be fixed. A solar charger won't fix it: it'll just hide the symptoms. If the battery isn't running flat, why add a solar charger?
Click to expand...
Because batteries sitting for long times go down hill, many folk don't have a charge point where they store the van if only used a few weeks a year, apart from bringing batteries home then duel solar is the way to go, my votronic works very well.solar duel a.png
 
I use exactly that one in mine, I’m running 4 x Bosch batteries and it maintains the charge for those and additionally the engine battery even during these dark days and darker nights. It’s performed perfectly for the many years I’ve used it.

They can be very difficult to get hold of.
 
I suggested you look at photonic universe, dual controller around £35 they will advise on cable size etc wire solar installation separately from any van electrics,also have helpline if you need advice
 
trevskoda said:
It only does a small panel, if you want to add more its no good, always buy bigger so you can add more or larger panel down the line, I think 200w is as small as id go knowing what I do now.
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For anyone who expects to want to spend any time off-grid, the approach I take is:

1) Fit as much solar as you can - or at least layout panels to reserve free space for additional ones
2) Fit a controller that can cope with the maximum amount of solar that can be fitted
3) Get an MPPT Controller rather than a PWM (equivalent of fitted 30% more Panels)
 
trevskoda said:
It only does a small panel, if you want to add more its no good, always buy bigger so you can add more or larger panel down the line, I think 200w is as small as id go knowing what I do now.
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I don't need bigger to charge a few devices.
 
trevskoda said:
Because batteries sitting for long times go down hill, many folk don't have a charge point where they store the van if only used a few weeks a year, apart from bringing batteries home then duel solar is the way to go, my votronic works very well.View attachment 62013
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Not had a problem since I fitted one of these
 
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