Hi!Ok, this time - a solar charge controller upgrade...
One of the niggles with the Benivan is that the 12V system is a bit 'cheap and cheerful'. The Sargent system (EC176?) contains a single stage battery charger - basically a 13.8V power supply to be honest and although you have a solar panel installed, the controller is a basic PWM one that is only capable of charging one battery at a time. There's a changeover switch to flip between charging the vehicle and leisure battery.
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Another drawback of the Sargent system is that it doesn't seem to charge the vehicle battery, just the leisure one. I've taken to leaving the solar panel set to 'Vehicle' when the van is parked up to keep the vehicle battery topped up and then switching it to 'Leisure' when we are using the van - works OK, but a bit of a faff.
As a bit of an aside here, the Sargent display panel shows the voltages for the batteries and a state of charge - poor/fair/good etc. It will also show 'charging' against the battery when it is being charged. To begin with I thought the Sargent control unit must be monitoring whether current was flowing to or from the battery, but actually it's a lot less sophisticated. 'charging' shows up if the battery voltage is 13.3V or above, which is probably fairly accurate as a lead/acid battery doesn't sit above 13V for long unless it is on charge.
Anyway, my goal here was to replace the factory fit solar controller with one that would
- Charge both batteries at once
- Get more power from the panel using MPPT rather than PWM
- Have a charging profile that is good for keeping the batteries in good health
- Fit in the space occupied by the current charge controller and
- Is compatible with a lithium battery if we choose to upgrade in the future.
A good deal of research led to choosing the Votronic MPP 165 Duo Digital, which covers pretty much all my requirements and is from a well respected brand rather than some unknown Chinese brand. Just under £100 and quick delivery from 12V Planet - I bought a few meters of cable that I didn't end up needing to push the amount up enough to get free delivery. Note that at least one brand of dual battery MPPT charge controller (PV Logic) requires batteries with separate ground connections rather than the common ground used in almost all vans - this should be avoided as it will not work correctly in a van where the batteries have common grounds.
So, first things first... removing the old controller.
My first step was to cover the solar panel with an old folded painting sheet - actually there was still obviously enough light getting to it through the sheet to generate an output voltage, but much lower than usual and not enough to run the charger.
Next, disconnect the charging circuits from the two batteries. Turn off the mains at the consumer unit, then remove the 20A fuse next to the leisure battery and the 20A 'vehicle battery' fuse in the little box on the floor behind the drivers seat. You can then verify zero volts at the existing battery charger using a voltmeter with the rocker switch in the 'I' then 'II' positions. Now there is no electrics active, you can start dismantling.
The existing charger has a single central screw holding it to the cupbard wall - pop that out and it comes loose. Now to remove the floor of the cupboard. This is held in with two screws under sticky covers at the back.
Handy hint... Get a hairdryer, set it to maximum heat, minimum blow and aim it at the sticky screw cover for about 60 seconds. Once it's warmed up, it should peel off fairly easily and you can just pop it on a PVC plastic bag until you need it at the end when putting stuff back together.
With the cupboard floor out, you can see that there's a lot of wiring under there!
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I also tried to remove the end wall of the cupboard - again two screws under sticky covers, but even with them taken out the wall was fixed - I suspect glued and screwed. Anyway, it turned out not to be necessary.
The rocker switch just pulls free - fingernails might be enough or you might need to carefully ease it out with a flat screwdriver.
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The top wire (brown/blue) is from the leisure battery, the bottom (brown/green) from the vehicle battery and the center (brown/orange) connects to the original charge controller. I verified the wiring by connecting each battery back up in turn and checking the voltage from the wires to the battery ground on the charge controller.
Next, disconnect the wiring. The white plastic bits just pull off the back of the toggle switch, while the wires to the charge controller can be simply unscrewed. Label each wire and tape off the ends with insulating tape as you disconnect them to avoid any accidental shorts.
You can then pull the three wires that go to the toggle switch gently from below to unthread them out of the wall.
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I'm sure there is some way to dissassembly the white push on blocks that came from the back of the toggle switch, but I just decided to cut the last inch of wire off with the plastic blocks going with it - there was plenty of slack available. The orange and brown wire that went to the center pin of the toggle can be removed as it is no longer needed, and the ground wire (white/orange) can be cut short to match the length of the two wires from the batteries.
Now we get to the fun bit of connecting up the new kit - leisure battery first (orange/white to negative, brown and blue to positive) and also connect the vehicle battery to the start battery + terminal on the controller. At this point you can re-insert the 20A fuses to bring the 12V power back - the 'MPP' light should flash, which is the controller saying 'no power from the panels, ready to go when we get some'. Now connect the panel wiring - observing correct polarity, red to positive - and remove the cover from the solar panel - the controller should kick into life!
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Excellent, now just to mount the controller properly and put things back together.
I used some electrical tape to bundle the cables and then fitted about 6 inches of mesh cable wrap I had handy from another project to give a tidy look.
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Four small screws mounts the controller on the cupboard wall, nicely covering the hole left by the old changeover switch. It's best to put the cupboard floor back in place first to make sure you right the wiring to go straight up from the hole that was there for the old charge controller wiring. Make sure your screws are no more than 15-16mm to avoid going right through the end of the cupboard and possibly hitting a cable behind. You can then screw the cupboard floor back down and restore the screw cover stickers you saved earlier.
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It all looks nice and tidy, with good space around the controller for ventilation even when the cupboard is in use. Note that this model (the 165) does not have a cooling fan - higher spec models in the same case do have a fan that apparently comes on when the controller gets hot.
Everything seems to be working as expected so far - a nice little mod to make the van that bit easier to use
cheers,
Robin
You posted this awhile back, but I wanted to ask if you happen to have more photos or maybe even a video. I have zero experience with electrical & was lost almost immediately, I am buying a 2024 BV 120 next month & if the solar charge controller is the same as your van’s, I definitely want a better one - especially as I want a lithium battery & possibly more solar. Thanks in advance.
