Victron smart solar load off but still powering
- Thread starter Freshtrax
- Start date
Turning the load off is just related to the load output on the mppt controller. That is actually a switched connection that takes its power from the battery, but is a seperate set of terminals on the mppt unit itself. I use that to power my pop top lights so I can turn the controller off and stop parasitic drain. It’s nothing to do with stopping the mppt from outputting via the output to battery. As long as you’ve got sunlight then you’ve got an output to the battery.
And as @ginkster says you should not have solar going into the Victron mppt without a battery connected, as per the instructions.
You can disable/enable the mppt charger in the settings on the app, but it pops up a warning to say that it is for maintenance purposes only. I would guess that prolonged use of this method will not be good for the unit.
And as @ginkster says you should not have solar going into the Victron mppt without a battery connected, as per the instructions.
You can disable/enable the mppt charger in the settings on the app, but it pops up a warning to say that it is for maintenance purposes only. I would guess that prolonged use of this method will not be good for the unit.
That’s exactly what’s happening - the MPPT output is connected to the lights at the battery. The system is working as expected given the way it’s connected.
Did the lights go out when it was dark and/or you disconnected the MC4? Without knowing this there’s little more we can do to help.
It's not the starter battery finding its way through via the same route, thinking here where I've got the Renogy DCC50S MPPT/B2B in the one unit?
I didn’t leave it connected until it went dark so can’t answer that.
Sounds like it’s normal behaviour and I need to:
1. Add an isolator to the mc4 cables from the panel.
2. Add my light switches (was going to anyway obviously)
What does everyone else do then? Surely your setups are similar with both the fuse board and mppt connected to the battery?
Have I just accidentally revealed this because I’ve not yet added light switches? When I add switches, will this all be ok? What do I do if I don’t want the solar constantly topping up the battery?
Sounds like it’s normal behaviour and I need to:
1. Add an isolator to the mc4 cables from the panel.
2. Add my light switches (was going to anyway obviously)
What does everyone else do then? Surely your setups are similar with both the fuse board and mppt connected to the battery?
Have I just accidentally revealed this because I’ve not yet added light switches? When I add switches, will this all be ok? What do I do if I don’t want the solar constantly topping up the battery?
I turn off my solar panels with a 30A double pole switch when I don't want them to do any more charging.
Usually by the time we've driven home from camping then the leisure battery is at 100% so getting rid of the power is more a thing.
Usually by the time we've driven home from camping then the leisure battery is at 100% so getting rid of the power is more a thing.
For the cost of a domestic double pole switch and box which is what I've used it means I can isolate the solar produced electric and not inadvertantly blow myself to smithereens as I'm farting around under the drivers seat pretending to fix stuff.
It's not really any different to isolating the leisure battery output or starter battery input.
It's not really any different to isolating the leisure battery output or starter battery input.
I have no need for an isolator for the solar, in the unlikely event of needing to isolate my panel, I would just remove the solar connection to the mppt, more connections isn't a good thing!
My solar comes into the rear hinge end of the pop top and my MPPT/B2B is under the drivers seat.
The panel leads reach into the wardrobe to the isolator and swap to a 6.00mm2 pair running to the drivers seat base, from an ex sparkys mindset it makes sense to be able to isolate cables running internally the length of the van.
The panel leads reach into the wardrobe to the isolator and swap to a 6.00mm2 pair running to the drivers seat base, from an ex sparkys mindset it makes sense to be able to isolate cables running internally the length of the van.
They’re only not switched yet because I haven’t installed the C-line switch panel. They’re were just wired to the fuse board to test them.
I’ve put an isolator between the panel and the MPPT. My logic is so I can disconnect the panel easily for maintenance or to control when solar charges the battery or not. Yes, I can do that via the app but flicking a switch is much quicker, easier and foolproof. Lithium batteries are not meant to be kept fully topped up so if you are not using the leisure system regularly I think it’s best to turn off the charging until you need it. Works for my usage anyhow. I do the same with the DC-DC so it doesn’t charge the battery every time I start the van.
Yes, you’ve just revealed how the system works if your lights don’t have switches, you disconnect the battery and have solar providing power. Having your lights switched (and all other loads) will prevent that. Also, do not switch off or isolate the battery with solar still connected as it doesn’t do the MPPT any good. One reason for the isolator. Personally I also avoid using the soft charging/discharging toggles in the Fogstar app as I’ve seen lots of people having issues on the Fogstar Facebook page. There should be no need with a properly set up system.
Do you have a diagram of your planned system? If so pop it on here and you’ll get some useful feedback. If not I’d suggest drawing one and fully planning your system before wiring stuff up. That will prevent expensive and potentially dangerous errors. There are a lot of amps (the dangerous bit) flying around in a seemingly innocent 12 volt system.
Thank you ginkster, I really do appreciate your help. 
Thanks so much for all the replies, what a great forum!!
I’ll be hopefully putting my switches in tomorrow and think I’ll do an isolator too on the panel to mppt positive.
As you say, Fogstar recommend storing at 30% charge for long periods and we will definitely be casual users so don’t want it full all the time.
I’ll keep in mind what you said about the soft toggles too. I’ve only been using them to test the lights and fridge work whilst I finish all the switches and seat base stuff.
Thanks again and I’ll keep updating as I go.
Thanks so much for all the replies, what a great forum!!
I’ll be hopefully putting my switches in tomorrow and think I’ll do an isolator too on the panel to mppt positive.
As you say, Fogstar recommend storing at 30% charge for long periods and we will definitely be casual users so don’t want it full all the time.
I’ll keep in mind what you said about the soft toggles too. I’ve only been using them to test the lights and fridge work whilst I finish all the switches and seat base stuff.
Thanks again and I’ll keep updating as I go.
No problem. The forum is an amazing place for help and info. And banter!Thank you ginkster, I really do appreciate your help.
Thanks so much for all the replies, what a great forum!!
I’ll be hopefully putting my switches in tomorrow and think I’ll do an isolator too on the panel to mppt positive.
As you say, Fogstar recommend storing at 30% charge for long periods and we will definitely be casual users so don’t want it full all the time.
I’ll keep in mind what you said about the soft toggles too. I’ve only been using them to test the lights and fridge work whilst I finish all the switches and seat base stuff.
Thanks again and I’ll keep updating as I go.
For the isolator you need to switch both pos and neg simultaneously so need a two pole switch that is suitably DC rated. You shouldn’t just switch the pos. I used this switch from Amazon for my 200w Renogy flexi panel:
Housed in this case from Screwfix:
Total cost about £12.
Don’t worry about being at 30% for the battery, just don’t leave it near empty or full (or constantly topped up). Anything between 20-90% is fine for weeks or a few months. If it’s going to be unused for 6 months plus then 50% is good. Ultimately it will just make it last longer just like managing the battery in a phone, laptop or EV. It’ll still last years without managing it like that.
