Votronic MPP solar controller to cab battery charging question

[Phill D]

I have fitted a Votronic MPP solar controller including connecting up to the cab battery. all through me EBL and no problems.

I have searched the tinterweb and cant get the info i am looking for so do any of you wise people know the answer and can put me out of my dilemma..

I know that the Votronic Mpp's allow a trickle charge of 1A to the cab battery. although there is no way of monitoring this with the standard set up even though i was able to do this previously with my Schaudt PWM Solar controller.
Now i can only see the habitation battery charge.

The Dilemma question i have is;
lets say i am getting 5 amps solar charge from my panel set up, so is the 1A going to the cab battery and 4 amps going to the liesure battery
or
is the full 5 amps going to the leisure battery and the cab battery has to wait until the liesure battery reach float charge before it gets its 1A trickle.

the reason for asking is that since changing to this solar controller i have noticed the cab battery voltage ( which is new in the past month ) dropping over a 24 hour period
before returning to full voltage.

 

[Phill D]

Anyone have any idea of the above or will I just have to set up my multimeter and measure it.

 

[KUSKUS]

That appears to be how mine works although my set up is EPEVER,
can you get an App to monitor your battery voltages ?

 

[barsteward]

I am no expert but I think the leisure batteries have priority over the cab. I have the Votrinic MPPT but I wired it directly to the batteries.

 

[Richard n Ann]

Our cab battery voltage goes up straight away so I think it doesn't wait for the leisure battery to charge first. Sounds like there's something draining it if it's dropping

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[Lenny HB]

Not very clear in their instructions but give the impression the leisure battery takes priority which is what I would expect. Most dual chargers only charge the starter battery when the leisure battery is up to 80/90%.
I have a Votronic MMP but I don't use that output I fitted a CBE CS2 relay as that will charge the starter battery all the time the leisure batteries have a good state of charge.

 

[Metamorfosis]

Been a while since I have done mine but just elaborate on what ebl you have and how exactly you have wired the votronic trickle to the cab battery as some ebls do not have passthrough for solar to cab battery and have to be wired through the back of the ebl

 

[Tengyneer]

We have the Votronic and l wired up the cables to the vehicle battery and fridge. Our vehicle battery does drain slightly, 0.3 or 0.4v during the periods of no light but once the light is back up it does return to normal. Vehicle battery maintains a charge of 13.7v and has started 1st time everytime since l fitted it 2 years ago, including being stood for 2 periods of 4 -5 months over the last year. Seems as though whatever is being fed into mine is doing the job. We have 420w of solar and it's never connected to electric.

 

[Phill D]

Been a while since I have done mine but just elaborate on what ebl you have and how exactly you have wired the votronic trickle to the cab battery as some ebls do not have passthrough for solar to cab battery and have to be wired through the back of the ebl

My ebl has a pass through to the cab battery and is wired through that.
All was well with no voltage drop showing when the lr1218 was wired exactly the same way.
I have had no issues with the cab battery and have just spent 6 nights off grid, with little sunlight for at least a day and a half.
So I am getting sufficient charge.
Just don't see why I note a cab voltage drop however small when that was not the case before the change.

I might look at an alternative to charge the cab battery and may just get the meter out and see for myself when I have a bit more time later in the week.

 

[Lenny HB]

My ebl has a pass through to the cab battery and is wired through that.
All was well with no voltage drop showing when the lr1218 was wired exactly the same way.
I have had no issues with the cab battery and have just spent 6 nights off grid, with little sunlight for at least a day and a half.
So I am getting sufficient charge.
Just don't see why I note a cab voltage drop however small when that was not the case before the change.

I might look at an alternative to charge the cab battery and may just get the meter out and see for myself when I have a bit more time later in the week.

THe Votroic is 1Amp output the LR1218 is 2amp might explain it.

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[Phill D]

THe Votroic is 1Amp output the LR1218 is 2amp might explain it.

Yep got that, but I still not sure if the lr1218 charged the cab on a full time basis and if it did that may be the difference.
One being full time charge available the other after leisure battery is at a given state.
Lenny HB how did you wire the csb2.

 

[Richard n Ann]

We use the cab radio during the day and the 1 amp is enough. Just drops to 12.6 during the night

 

[Phill D]

We use the cab radio during the day and the 1 amp is enough. Just drops to 12.6 during the night

perhaps i am getting paranoid in my old age....

 

[Lenny HB]

Yep got that, but I still not sure if the lr1218 charged the cab on a full time basis and if it did that may be the difference.
One being full time charge available the other after leisure battery is at a given state.
Lenny HB how did you wire the csb2.

Input to the CBS 2 (Black Neg & Red Pos) to the main sloar output or you can connect to leisure battery, output (blue) to the starter battery connection on the solar connections on the EBL or you can connect to the starter battery.

Hate to say this today I have discovered my CBS 2 has failed, I noticed yesterday after the suspension compressor was running starter battery recovered to 12.7v but after a couple of hours it was still at 12.7v and this morning still 12.7v. At least the new battery is holding its voltage well, I think the CBS 2 must have been intermittent for a while and that's what caused my starter battery to go flat. It was 6 years old I had it in the last van.
I will replace it but appears to be a shortage at the moment only ones for sale way above normal price. For now I've just wired the 1amp output from the Votronic to the EBL after an hour voltage up to 13.2v.

 

[Phill D]

Input to the CBS 2 (Black Neg & Red Pos) to the main sloar output or you can connect to leisure battery, output (blue) to the starter battery connection on the solar connections on the EBL or you can connect to the starter battery.

Hate to say this today I have discovered my CBS 2 has failed, I noticed yesterday after the suspension compressor was running starter battery recovered to 12.7v but after a couple of hours it was still at 12.7v and this morning still 12.7v. At least the new battery is holding its voltage well, I think the CBS 2 must have been intermittent for a while and that's what caused my starter battery to go flat. It was 6 years old I had it in the last van.
I will replace it but appears to be a shortage at the moment only ones for sale way above normal price. For now I've just wired the 1amp output from the Votronic to the EBL after an hour voltage up to 13.2v.

i think i might just live with it for a while and i may become less paranoid about it...

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[Deneb]

Had the Votronic controller on my van for nearly 5 years and also have a Victron BMS. Although the BMS doesn't measure current to the vehicle battery, it does monitor its voltage. I believe the controller trickle charges the vehicle battery continuously whenever there is sufficient solar charge being generated, as I see the vehicle battery voltage rise together with the leisure battery voltage as soon as the sun comes up and the controller switches to charging mode. The reason you see a voltage drop is because the vehicle battery tends to receive a float voltage (or as near as the controller can maintain, depending on light conditions) for most of the day. As soon as the controller switches off when the sun goes down, the battery is no longer receiving an increased voltage and will gradually drop to its resting voltage throughout the night. The following morning, the sun comes up, the controller switches to charging mode and the battery voltage rises again.

I believe from memory the manual says that the vehicle battery receives a maintenance charge of up 1 amp, which suggests to me that in less than optimum conditions, the current may be less. Some of the Votronic controller supply a lower maximum charge to the vehicle battery anyway, 0.5 or 0.8 amps depending on the model AFAIR.

I also have a Votronic B2B fitted. When wired to be controlled by a D+ signal , the controller configures itself to also supply a trickle charge of up to 1 amp to the vehicle battery from the leisure batteries, whenever the leisure batteries are receiving or at a voltage of more than 13.1 volts, i.e. when receiving solar or mains charging input. Again, the manual says "up to 1 amp" and depends on the condition of the vehicle battery. I don't think either of the Votronic units will attempt to charge a fully charged vehicle battery for instance, but both will attempt to maintain a float voltage to the vehicle battery, all other conditions being met.