Having spent the last couple of weeks sorting out my battery setup I'm curious if anyone has a switch similar to the one I've attached to switch mains to the inverter feed supplying power to all installed sockets in the motorhome?View attachment 945092
Battery to mains feed switch. (2 Viewers)
- Thread starter acenip
- Start date
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Excellent 
Do you power your fridge from this same feed?
We've always used gas to power our fridge as we never use sites, from our initial tests using mains appliances it looks like we could easily run the fridge this way.
Do you power your fridge from this same feed?
We've always used gas to power our fridge as we never use sites, from our initial tests using mains appliances it looks like we could easily run the fridge this way.
No I always had the fridge on gas, but now it's a compressor fridge that is always powered by the leisure battery and solar.Excellent
Do you power your fridge from this same feed?
We've always used gas to power our fridge as we never use sites, from our initial tests using mains appliances it looks like we could easily run the fridge this way.
Sorry, a bit confused. Our fridge is a 3 way model. Before we leave home we run it on plugged in mains to bring the temperature way down. Do you think it would be prudent, power wise to run it from the 200ah lithium battery once we stop on our journey?
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No, the 3 way fridges use lots of power, upwards of 120w, which is at least 10 amps on 12v and would be even more through an inverter.
Ok to use mains if you're on hook up, or 12v if the engine alternator is providing power but when parked up you're better off using gas
Not much to show but I got the switch over fitted. Works exactly as it should.
I'm probably going to need my asbestos underpants for the next part
Our fridge mains switch stays on at all times as we seldom plug the motorhome mains in at all. So while I was testing the new plug I was flicking the individual fuse trips. When I put the fridge one up the fridge switch lit up but my inverter cooling fan didn't come on, I thought this was an error or bug, so I did further checks with a thermometer gun. It's definitely cooling down, I've done half hour checks for the last 3 hours. The icebox started out at +10.9° around 9.15am and at 12noon it's at -18°
Am I missing something?
The inefficiency mentioned isn't clear to me but perhaps 3 hours isn't much of a test. I would have assumed the main grunt work here was getting the temperature to fall and that keeping it down would be easier with a full fridge and the door permanently closed.
Please be gentle
I'm probably going to need my asbestos underpants for the next part
Our fridge mains switch stays on at all times as we seldom plug the motorhome mains in at all. So while I was testing the new plug I was flicking the individual fuse trips. When I put the fridge one up the fridge switch lit up but my inverter cooling fan didn't come on, I thought this was an error or bug, so I did further checks with a thermometer gun. It's definitely cooling down, I've done half hour checks for the last 3 hours. The icebox started out at +10.9° around 9.15am and at 12noon it's at -18°
Am I missing something?
The inefficiency mentioned isn't clear to me but perhaps 3 hours isn't much of a test. I would have assumed the main grunt work here was getting the temperature to fall and that keeping it down would be easier with a full fridge and the door permanently closed.
Please be gentle
So the fridge is working off 230v provided by the inverter?
Have you looked at the battery voltage?
Have you looked at the battery voltage?
pappajohn
LIFE MEMBER
Cooling just the same as being on mains but did you also check battery voltage after 3 hours to check battery drain?
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Just posted above. Do I need to switch off the solar for a true reading.
pappajohn
LIFE MEMBER
Your inverter is powering the charger.... You are seeing charger voltage, not battery voltage. (the charger will take more from the battery via the inverter than it can ever put back into the battery)
Switch off charger then check again after 3 hours
pappajohn
LIFE MEMBER
Most vans have a mains powered built in habitation battery charger which turns on automatically when you connect to a mains supply. If you have wired your switch to supply all the circuits in your van it the charger will turn on and try to charge your battery whilst also being powered by the same battery. It's normal when using this change-over system to turn off or isolate the onboard charger.
Your fridge will use up all your 200amps of battery power over about 24 hours if you use no other appliances/lights etc. It's probably unlikely your solar will be able to replace this amount of power?
To get a true reading of the drain on your battery you need to isolate all charging sources that are replenishing the battery.
Your fridge will use up all your 200amps of battery power over about 24 hours if you use no other appliances/lights etc. It's probably unlikely your solar will be able to replace this amount of power?
To get a true reading of the drain on your battery you need to isolate all charging sources that are replenishing the battery.
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Kannon Fodda
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Any fan in the inverter for cooling will only start up when inverter temperature rises. Speed of fan also depends on temperature. So your fridge only load may not be that much compared to the max power inverter could do.
Battery voltages are best checked at rest so no charge or discharge loads for 30 minutes. During your daytime testing the solar system is on and trying to put a charge into the habitation system. To put in a charge the voltage of solar will be higher than that of yourc12v leisure system and the battery. Hence you are falsely seeing the electronics showing a volt rise from 13.0v to 13.2v. Turn off the inverter and solar you will probably see volt has dropped.
But you have lithium. The voltages don't change much until approaching complete discharge. To really see the state of the battery look at it's state of charge, SOC, from the Amphours, Ah, left. This may be shown in the battery BMS app, or alternatively fit a shunt which would have measured the current in and out.
Battery voltages are best checked at rest so no charge or discharge loads for 30 minutes. During your daytime testing the solar system is on and trying to put a charge into the habitation system. To put in a charge the voltage of solar will be higher than that of yourc12v leisure system and the battery. Hence you are falsely seeing the electronics showing a volt rise from 13.0v to 13.2v. Turn off the inverter and solar you will probably see volt has dropped.
But you have lithium. The voltages don't change much until approaching complete discharge. To really see the state of the battery look at it's state of charge, SOC, from the Amphours, Ah, left. This may be shown in the battery BMS app, or alternatively fit a shunt which would have measured the current in and out.
With 400watts of solar it all sounds OK then
the solar is keeping the battery happy. The inverter isn't draining the battery hence the 13.2vIs the sun shining?
Get a monitor for the battery, you can see exactly what's happening then 
Only about £100
Only about £100
Yes, cloudy but sun at times. It's went to Absorption, so unless the controller is confused there seems to enough solar. Fridge still on mains, I've turned it down to2 it was up full until nowWith 400watts of solar it all sounds OK then
Is the sun shining?
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I've ordered a shunt, so proper monitoring will be possible shortly.
I ran the fridge via the inverter overnight, so this morning here's what the controller app was showing around 7am.
The solar was disconnected until around 8am.
I ran the fridge via the inverter overnight, so this morning here's what the controller app was showing around 7am.
The solar was disconnected until around 8am.
"Luvshack"? 
What do you call yours?"Luvshack"?
Just "the van" sadly
Tombola
LIFE MEMBER
What lithium battery do you have,
I had 200 ah of lithium, and ran my 3way fridge off it , more often than not it would take 110ah + in 24 hours, it would pull 10-12 ah via inverter when on via the battery app, but obviously they cycle on and off..
I have 400ah now so its not much of an issue, but when I had 200 and the weather wasnt sunny or I wasnt driving to add more via b2b, then it was certainly a close call most days. Some nights Id switch it off.
I had 200 ah of lithium, and ran my 3way fridge off it , more often than not it would take 110ah + in 24 hours, it would pull 10-12 ah via inverter when on via the battery app, but obviously they cycle on and off..
I have 400ah now so its not much of an issue, but when I had 200 and the weather wasnt sunny or I wasnt driving to add more via b2b, then it was certainly a close call most days. Some nights Id switch it off.
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I've a DC HOUSE LiFePO4 12V 200AH battery.
Once I fit the shunt and hit a couple of duller days I'll probably be seeing things differently.
Tombola
LIFE MEMBER
yeah get yourself the shunt in then you can monitor it as much as you want.
It will work for now, you just have to keep a close eye on it, and as you say keep the charger disabled when not on hookup if the inverter powers that too.
You can always switch the fridge to gas when you need to.
I wired my mains charger straight from the hook up point via a fused spur, so when I changeover to inverter it doesn't receive power from the inverter.
I've been discussing my mains to inverter swich install in this forum, but at the same time I was chatting about running my fridge on mains from my lithum using only solar. Fitting a shunt was the loudest advice, this I have now installed. Along my jouurney I noted a link to a youtube about the initial settings for the shunt. I can't find this link in either chat, could somebody send me this link please?
The one I use are,
Battery in Amp
Charging voltage 14.00 volts
Discharge voltage floor 5%
Tail current 2%
Charge efficiency 98%
Charge detection 3 mins
Peukert exponent 1.05
Current threshold 0.10 amps
Time to go average 3 mins
Theses are for the Victron shunt
Battery in Amp
Charging voltage 14.00 volts
Discharge voltage floor 5%
Tail current 2%
Charge efficiency 98%
Charge detection 3 mins
Peukert exponent 1.05
Current threshold 0.10 amps
Time to go average 3 mins
Theses are for the Victron shunt
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