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Victron charge controller + temp sensor vs BMS low temp cutoff?

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Smeeg

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Building my system on paper it’s going to be 400 watts with a 24v 100ah lifepo4 to start out. This is for a hunting cabin in the northeast that will be vacant in the winter time. So I need low temp cutoff protection I also want the system to be hands off so I would rather not rely on people remembering to turn off the solar panels before they leave.
I’ve narrowed it down to victron 50 amp charge controller + smart battery sense & Litime 24v 100 ah battery vs.
epever 40amp BN series charge controller with SOK 24v100 ah
I plan on building an insulated box or using a cooler to put the battery inside either way. The victron on paper comes out ahead monetarily I really don’t trust bluetoooth that much though. Did I miss an option? what would you do in my situation?

Also what would your procedure be when you left the cabin disconnect solar panels with a DC circuit breaker but leave battery connected?
 
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Smeeg said:
Building my system on paper it’s going to be 24v 400 watts with 24v 100ah lifepo4 to start out.
Click to expand...

with MPPT, there is no reason to pair 24V panels with a 24V battery, but that's fine.

Smeeg said:
This is for a hunting cabin in the northeast that will be vacant in the winter time. So I need low temp cutoff protection I also want the system to be hands off so I would rather not rely on people remembering to turn off the solar panels before they leave.
I’ve narrowed it down to victron 50 amp charge controller + smart battery sense & Litime 24v 100 ah battery vs.
epever 40amp BN series charge controller with SOK 24v100 ah
Click to expand...

Both are valid options, but I prefer Victron hands down. A 50A MPPT is limited to 28V * 50A = 1400W (-ish)

Smeeg said:
I plan on building an insulated box or using a cooler to put the battery inside either way.
Click to expand...

Good.

Smeeg said:
The victron on paper comes out ahead monetarily I really don’t trust bluetoooth that much though. Did I miss an option? what would you do in my situation?
Click to expand...

SBS has an excellent record. I have one, and I've never heard of one failing. If the battery and MPPT are located nearby, I can't imaging the BT signal would be an issue. Additionally, if the MPPT loses its signal, it will use its own "power on temp reading,", i.e., the first temperature it measures when powering up - before its own operation causes heating. If it's below the temp setting, it will not charge all day.

Smeeg said:
Also what would your procedure be when you left the cabin disconnect solar panels with a DC circuit breaker but leave battery connected?
Click to expand...

If you have absolutely nothing you need to power, disconnect battery.
 
sunshine_eggo said:
with MPPT, there is no reason to pair 24V panels with a 24V battery, but that's fine.



Both are valid options, but I prefer Victron hands down. A 50A MPPT is limited to 28V * 50A = 1400W (-ish)



Good.



SBS has an excellent record. I have one, and I've never heard of one failing. If the battery and MPPT are located nearby, I can't imaging the BT signal would be an issue. Additionally, if the MPPT loses its signal, it will use its own "power on temp reading,", i.e., the first temperature it measures when powering up - before its own operation causes heating. If it's below the temp setting, it will not charge all day.



If you have absolutely nothing you need to power, disconnect battery.
Click to expand...

I wrote the 24v thing wrong I’m going to use four HSQ 100 watt panels with a 24v battery.
My concern is if I have a switch to disconnect the battery & a dc breaker for the solar panels
If they switch off the battery first before the solar panels doesn’t that have the potential to destroy the charge controller? Im trying to make it so it’s impossible to screw up
 
My victron SmartSolar controllers have the faultless.

You can isolate the PV anytime you wish to stop charging via a temperature controlled switch.
 
A couple of other ideas…

Instead of the battery sense - think about a Smartshunt and add the battery temp sensor. Then setup the Bluetooth VE.Network to pass temp, voltage and current along.

Do you have Internet at the cabin? Doubt it… but if you do think about getting a Cerbo, plus the ve direct cables to attach the Victron mppt & Smartshunt. You can then use VRM to monitor the electrical system (and I believe even make changes) from home (or anywhere else that has internet)

I do like your idea of making sure there is never charging current when batteries are too cold. I did the same thing.

The BMS is a backup - a critical backup.
 
Smeeg said:
I wrote the 24v thing wrong I’m going to use four HSQ 100 watt panels with a 24v battery.
My concern is if I have a switch to disconnect the battery & a dc breaker for the solar panels
If they switch off the battery first before the solar panels doesn’t that have the potential to destroy the charge controller? Im trying to make it so it’s impossible to screw up
Click to expand...

Once initially set for system voltage, the MPPT can operate batteryless purely on PV. It's a feature.

Rocketman said:
Instead of the battery sense - think about a Smartshunt and add the battery temp sensor. Then setup the Bluetooth VE.Network to pass temp, voltage and current along.

Do you have Internet at the cabin? Doubt it… but if you do think about getting a Cerbo, plus the ve direct cables to attach the Victron mppt & Smartshunt. You can then use VRM to monitor the electrical system (and I believe even make changes) from home (or anywhere else that has internet)
Click to expand...

Agree with both!
 
Rocketman said:
A couple of other ideas…

Instead of the battery sense - think about a Smartshunt and add the battery temp sensor. Then setup the Bluetooth VE.Network to pass temp, voltage and current along.

Do you have Internet at the cabin? Doubt it… but if you do think about getting a Cerbo, plus the ve direct cables to attach the Victron mppt & Smartshunt. You can then use VRM to monitor the electrical system (and I believe even make changes) from home (or anywhere else that has internet)

I do like your idea of making sure there is never charging current when batteries are too cold. I did the same thing.

The BMS is a backup - a critical backup.
Click to expand...
No wifi



With these two^ I would get low temp protection without Bluetooth? Looks nice but expensive.

with your system do you turn of your solar panels & leave the battery connected or shut off both?
 
Smeeg said:
No wifi



With these two^ I would get low temp protection without Bluetooth? Looks nice but expensive.

with your system do you turn of your solar panels & leave the battery connected or shut off both?
Click to expand...

Wrong temperature sensor. You want the one for the BMV, not the quattro.

The smartshunt still relies on bluetooth. The only way to eliminate bluetooth is to get a Cerbo and connect both the shunt and the MPPT to the Cerbo with VE.Direct cables. You will not need BT for anything at that point as the Cerbo distributes information between connected components.

Rocketman said:
Do you have Internet at the cabin? Doubt it… but if you do think about getting a Cerbo, plus the ve direct cables to attach the Victron mppt & Smartshunt. You can then use VRM to monitor the electrical system (and I believe even make changes) from home (or anywhere else that has internet)
Click to expand...

Absolutely. I can make any changes I want to my Quattros, BMV, MPPT and GX remotely including firmware updates. I was scared shitless to do a remote firmware update of the Quattros as even Victron recommends a "if it ain't broke, don't fix it" attitude on inverter firmware upgrades. I had a version from 2019, and I wanted an updated version that includes low temp charge protection built into the inverter itself.

I did it "remotely' while on-site, i.e., I used VRM to do it while I was there to address any fallout. Went exactly as the instructions indicated, and it was completely painless. I don't know that I'll be able to get past the mental barrier of doing it truly remotely for the inverters, but I do the BMV, MPPT and GX remotely regularly.

1689371092466.png



Lastly, you can use VictronConnect to connect to your VRM and monitor/manage any VE.Direct connected devices as though you were local and on bluetooth.
 
What are the winter temps at your cabin?

Is the average of high and low above 35 degree’s? (For the most part?)

Are you planning on shutting the system down for the winter or keeping it up?

Have you considered adding heaters next to the batteries - inside the insulation.

If the winter highs are seldom above 35 degrees- you may be safer shut the system completely down. Then restart the first time back there.

With a good plan it is not difficult to keep batteries going over the winter - but panels need to collect more watts than you expend heating and running the batteries.
 
Rocketman said:
What are the winter temps at your cabin?

Is the average of high and low above 35 degree’s? (For the most part?)

Are you planning on shutting the system down for the winter or keeping it up?

Have you considered adding heaters next to the batteries - inside the insulation.

If the winter highs are seldom above 35 degrees- you may be safer shut the system completely down. Then restart the first time back there.

With a good plan it is not difficult to keep batteries going over the winter - but panels need to collect more watts than you expend heating and running the batteries.
Click to expand...
It’s upstate NY with zero insulation so yes I’d say average temp is below 35 degrees.
I’m leaning towards shutting it down in the winter (don’t need anything to run while I’m not there) but still not sure if that means just disconnecting the panels or also disconnecting the battery? Other people also use the cabin so would like to keep the shut down procedure as simple and fool proof as possible.
 
For the panels you will want some way to “turn the sun off”. I put a cheap (Amazon) breaker on the positive wire between the panels and the mppt.

Flip that breaker and turn off the bms and the system will be off.

If you have several people using the system- take a close look at installing the Cerbo &touch. The reason is one glance at it and you can see the battery percentage and also how much you are charging and if the battery is going up or down. Very easy for my wife to understand what is going on. (If you have an inverter- go all Victron because it will then show up on the screen too). Watch a few YouTube to get a good understanding.
 
Rocketman said:
For the panels you will want some way to “turn the sun off”. I put a cheap (Amazon) breaker on the positive wire between the panels and the mppt.

Flip that breaker and turn off the bms and the system will be off.

If you have several people using the system- take a close look at installing the Cerbo &touch. The reason is one glance at it and you can see the battery percentage and also how much you are charging and if the battery is going up or down. Very easy for my wife to understand what is going on. (If you have an inverter- go all Victron because it will then show up on the screen too). Watch a few YouTube to get a good understanding.
Click to expand...


For solar panels ^


Positive side of battery terminal/wire ^

I would need both of these? I prefer a physical switch over a program/ app ect
 
If the cabin will be vacant for months then disconnecting everything is the way to go. My RV trailer sits in the storage lot for 3 to 4 months during the winter, but I'm there at least once a month working on "projects". I installed a warming system to keep my DIY LiFePO4 batteries above 35°F so they could be charged when the sun comes up. It works well. If I wasn't at the RV so much in the winter, I would just turn the system off. I do camp when the outside temperatures are below freezing so the warming system on the batteries ensures I can always charge the batteries.
 
Epever low temp cutoff video

Discovered that the epever AN series has low temp cutoff/protection so may go Tracer4210AN 40 amp SCC + litime 24v 100ah battery. I like that the temp sensor is hard wired wish that I could edit the low temp cutoff from the screen instead of a computer & wish the max VOC was higher
 
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