Suitable switch for isolating solar panels

[headlight]

I have 2 x 100 watt solar panels to a Victron 75-15 MPPT.
I want to be able to stop the panels charging my LifePo4 leisure battery.
Therefore I need a switch between the panels and MPPT.
Suggestions for a suitable switch please.

 

[headlight]

Turn the off in the app

That's what I do but the Victron shunt SOC has started recording a charge whilst the battery charge is off.

 

[eddie]

That's what I do but the Victron shunt SOC has started recording a charge whilst the battery charge is off.

Ok then pull the fuse in the Victron Solar regulator

Physically can’t be them then, see what happens

 

[pwilmo]

this is well made DC isolator, the screw holes give a solid fix to wall,with a lock position

https://voltaconsolar.com/products/solar-pv-dc-switch-disconnector-din-rail-32a-1200v?currency=GBP&variant=47438491025742&utm_source=google&utm_medium=cpc&utm_campaign=Google%20Shopping&stkn=bb0a16c72bb4&gad_source=1&gclid=EAIaIQobChMI0MPX9-a0hgMVm5xQBh33fATqEAQYISABEgJC2fD_BwE

 

[headlight]

Ok then pull the fuse in the Victron Solar regulator

Physically can’t be them then, see what happens

Yes pulling the fuse would isolate the panels.
Only thing is the MPPT fuse is awkward to access due to location which is why I'm fitting a switch.

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[eddie]

Yes pulling the fuse would isolate the panels.
Only thing is the MPPT fuse is awkward to access due to location which is why I'm fitting a switch.

If by pulling the fuse the problem still exists, it’s not the panels, so you wouldn’t need to fit a switch

 

[headlight]

If by pulling the fuse the problem still exists, it’s not the panels, so you wouldn’t need to fit a switch

Yes you are correct

 

[pwilmo]

Yes, fitting the DC isolator switch is so easy, I had the same problem.
Pull out the solar live into the MPPT , route it into your in position on DC switch .
Run a cable (the correct diam/size )from the out of the switch(in the off position) into the feed of the solar MPPT ..job done

 

[eddie]

The fewer connections the better, less chance of potential problems in the future

 

[headlight]

I've just got off the phone to Fogstar.
They say it is the BMS down to the way I'm using the battery.
They said I'm not draining the battery enough as my usual daily use is around 50 amps or just over 20% then the battery is recharged to 100% SOC by either my solar or B2B.
They advised that I take the battery down to between 20 and 30% then fully charge the battery to 100% to reset the BMS.
They also said that when you turn charge off in the app you are not truly turning charging off and to truly turn charge off you also need to turn discharge off.
They said that on their new app you will only have the option to have both charge and discharge on or off not one on and one off.

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[Tombola]

have you tried turning the charge off in the victron app and not the battery app?

 

[headlight]

have you tried turning the charge off in the victron app and not the battery app?

No.
TBH I hadn't thought of that doh

 

[Camper634]

I fitted these.Been ok up to now

 

[Tombola]

for anyone who stumbles on this thread and doesnt know,,,BUT its always handy to have a switch on the panel side of the MPPT if you ever want to work on it.

 

[Vansflyer]

No.
TBH I hadn't thought of that doh

The only issue with doing this is that the battery master may not see enough voltage to trickle the cab battery whilst in storage.
I fitted the Ablemail unit as that can be configured to constantly trickle the cab battery regardless of solar input.
BTW I also have a Fogstar and Victron shunt set up and when charging "turned off" on the fogstar the SOC never ties up with the Shunt reading. I ignore the BMS and look at the cell voltage and work out the Soc from there. Hopefully the cell voltage is correct and if it isn't my calculation is screwed
After a few days travelling BMS and shunt SOC are reading the same SOC so not sure what changes as the parasite drain below 1A is still the same... answers on a postcard to:
Fogstar Confusion.US

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[eddie]

have you tried turning the charge off in the victron app and not the battery app?

That's what I meant

 

[headlight]

Fogstar say I have confused the BMS by only draining the battery by around 20% - 25% then recharging to 100% and that the confused BMS is causing the issue.
In the winter I didn't have this issue, possibly because the battery was being drained lower and solar was producing much less amps.
They said that even though I'm turning charge off that as the BMS is confused it may actually still be allowing charging.
I'll try a few things over the weekend and see if I can work out what is going on.
Thanks for all the advice so far.
The battery itself is working fine its just the odd shunt SOC readings.

 

[headlight]

Giving this some more thought what Fogstar told me can't be correct.
That is that the BMS is confused and might still be allowing charging even though charge is turned off in the app and that that is why my shunt is climbing to 100% SOC.
That can't be right as the BMS app SOC doesn't increase which if charging is happening it would climb to 100% SOC the same as the shunt does ?

 

[denisejoe]

I put an inline fuse in

As I was going to say just pull the fuse

 

[eddie]

OK so you need to establish whats what

Pull the fuse in the Victron regulator OR turn the Victron solar regulator charge OFF in the Victron App

After that if the battery is charging you have eliminated the solar panel

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[headlight]

OK so you need to establish whats what

Pull the fuse in the Victron regulator OR turn the Victron solar regulator charge OFF in the Victron App

After that if the battery is charging you have eliminated the solar panel

That is one of the things im going to try on the weekend.
As the only possible charge source is solar, as the van is parked up, then obviously the battery won't receive any charge.

 

[eddie]

Well perpetual motion hasn't been developed yet

Turn of the Victron regulator using the victron app

If it keeps doing it, you Fogstar info is wrong

 

[headlight]

So a little update.
When I went to the van last Tuesday although charge was turned off in the Fogstar app my Victron shunt had climbed from the 80% SOC it had been at when I parked it up a week earlier to 100% SOC, the Fogstar app was still showing 80% SOC.
I went to the van again on Friday and the shunt was showing 100% SOC but strangely the Fogstar app was now showing 95 % SOC.
Charge was still turned off in the Fogstar app ?
Reading a few threads on the Fogstar forum some people were reporting that although they had turned charge off in the app that if a drain was placed on the battery it would start charging even though the charge was still showing as off in the app.
Stop the drain and it would stop accepting a charge.
I'm now wondering if when the Battery Master takes amperage, I leave discharge on for the Battery Master to work, from the leisure battery it starts charging as some other owners have reported ?
Anyway as advised on here from now on I'm going to leave charge on in the Fogstar app and disable charging in the Victron solar app and see what that does as there will definitely be no charge.
As I posted earlier I have had the set up for 6 months and its only the past month its started doing this.
Nothing has been changed, altered or added.

 

[eddie]

If fitted correctly the Battery Master will be post the shunt, so anything towards the engine battery will register on the shunt

Also, the internal BMS will have a quiescent drain, again recordable on the shunt

As previously suggested turn the charge off in the Victron solar app and nothing further should happen

 

[headlight]

If fitted correctly the Battery Master will be post the shunt, so anything towards the engine battery will register on the shunt

Also, the internal BMS will have a quiescent drain, again recordable on the shunt

As previously suggested turn the charge off in the Victron solar app and nothing further should happen

Moving forward I will be disabling charge in the Victron solar app as suggested.
I'm just trying to work out how the shunt SOC rose from 80% to 100% in a few days but the app SOC remained at 80% for over a week then rose to 95% in 2 days but charge was disabled in the Fogstar app the whole time and in the previous 5 months this behavior never happened ?

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[headlight]

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The above is a link to a video posted on the Fogstar forum showing their charge turning itself on when a drain is placed on the battery and off when the drain is stopped even though they have charge turned off in the app.

 

[autorouter]

They also said that when you turn charge off in the app you are not truly turning charging off and to truly turn charge off you also need to turn discharge off.
They said that on their new app you will only have the option to have both charge and discharge on or off not one on and one off.

One reason to have the charge and discharge switched separately is for when the temperature is below zero. You want to avoid charging below zero, but you will often want to use power from the battery below zero - to power the heating controls for example. Does that mean that a Fogstar battery will be totally useless below zero C?

 

[Northernraider]

Don't remember that, I found out when doing Tam's install as he bought a couple them, warm with only 30 amps flowing through them they are supposed to take 300 amps.
Cranking the terminals up to far higher torque than you should they were much cooler but that was only at 30 amps.

They only got hot that first couple of times uncle lenny , afterwards theyvr been fine .. I check them every so often to make sure.

 

[Northernraider]

Fogstar say I have confused the BMS by only draining the battery by around 20% - 25% then recharging to 100% and that the confused BMS is causing the issue.
In the winter I didn't have this issue, possibly because the battery was being drained lower and solar was producing much less amps.
They said that even though I'm turning charge off that as the BMS is confused it may actually still be allowing charging.
I'll try a few things over the weekend and see if I can work out what is going on.
Thanks for all the advice so far.
The battery itself is working fine its just the odd shunt SOC readings.

That's interesting as I only ever use 20% of my charge too on my 105ah fogstar . Never get a chance to run it down more tbh. But might be worth me trying every so often.

 

[Lenny HB]

One reason to have the charge and discharge switched separately is for when the temperature is below zero. You want to avoid charging below zero, but you will often want to use power from the battery below zero - to power the heating controls for example. Does that mean that a Fogstar battery will be totally useless below zero C?

Fogstar has a built in heater so it won't allow charging until the battery is up to 5 °.

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[Lenny HB]

They only got hot that first couple of times uncle lenny , afterwards theyvr been fine .. I check them every so often to make sure.

But you draw naff all current through them I wouldn't want to risk then at 200 amps.