Thermistor wire for temp

[tmcblane]

So it seems like I have seen a couple times that the temp sensor shouldnt be connected to lithium batteries, I think my xantrex or Victron monitor may have been one but is there a particular reason or am I dreaming? Thanks for the input!

 

[Bud Martin]

So it seems like I have seen a couple times that the temp sensor shouldnt be connected to lithium batteries, I think my xantrex or Victron monitor may have been one but is there a particular reason or am I dreaming? Thanks for the input!

Please clarify the "shouldnt be connected to lithium batteries"? Do you mean electrically or physically?
Also the ref where this info is from?

 

[tmcblane]

Please clarify the "shouldnt be connected to lithium batteries"? Do you mean electrically or physically?
Also the ref where this info is from?

Good question Bud, seems to me it was a wire that came with the meter or charger but I think it was the meter that said not to use it. I think it is the current Victron meter I have, maybe the 712?? So pretty sure it had a lug on it to connect to the positive of battery

 

[Bud Martin]

I think we need the details of what you have and the document that comes with it. The lug is more likely for it to be able to mount the sensor on the surface of what you are trying to sense the temperature, the sensor itself has no electrical connection to the mounting lug, it is isolated, it will be a really bad design for the temp sensor to have electrical connection to the mounting lug, it should also have the spec of what the break down Voltage of the sensor isolation is.

 

[timselectric]

If you are talking about the charger temperature sensor that you used to connect to led acid batteries.
Then no, it's not used for Lithium phosphate batteries.

 

[tmcblane]

If you are talking about the charger temperature sensor that you used to connect to led acid batteries.
Then no, it's not used for Lithium phosphate batteries.

Tim, I think that is probably what it was. Thanks for info!
Would it not be used because the BMS monitors it??

 

[timselectric]

Tim, I think that is probably what it was. Thanks for info!
Would it not be used because the BMS monitors it??

Correct, Lifepo4 batteries don't heat up like led acid.
They have less internal resistance. The charging current doesn't have to be forced into them.

 

[chrisski]

My temperature sensor from my VIctron 712 is the main way to stop under temp charging on lithium batteries. The temp sensor is used to trigger the SCC to stop charging below a certain temp, and set lower than that is the BMS‘S temp sensor. BMS should not be the primary way to disconnect. Not sure how the BMS would react to 100 amps from the solar panels being stopped with the FETs for hours on end. Using the Victron 712 to stop the SCC, that current is not there.

So yes, still connect the Victron temp sensor for that.

You don’t need to worry about temp compensation like lead acid, but the VIctron 712 battery monitor networks with otherVictron Devices for many uses.

 

[tmcblane]

Correct, Lifepo4 batteries don't heat up like led acid.
They have less internal resistance. The charging current doesn't have to be forced into them.

But if you hooked it up it hurts nothing I assume? I didnt hook it up on mine but just wanted some info on why or if there is a reason it shouldnt be. Thanks in advance

 

[timselectric]

My temperature sensor from my VIctron 712 is the main way to stop under temp charging on lithium batteries. The temp sensor is used to trigger the SCC to stop charging below a certain temp, and set lower than that is the BMS‘S temp sensor. BMS should not be the primary way to disconnect. Not sure how the BMS would react to 100 amps from the solar panels being stopped with the FETs for hours on end. Using the Victron 712 to stop the SCC, that current is not there.

So yes, still connect the Victron temp sensor for that.

You don’t need to worry about temp compensation like lead acid, but the VIctron 712 battery monitor networks with otherVictron Devices for many uses.

That's a different sensor than the one used for led acid batteries. Always follow manufacturers instructions. Otherwise you could be voiding the warranty.

 

[timselectric]

But if you hooked it up it hurts nothing I assume? I didnt hook it up on mine but just wanted some info on why or if there is a reason it shouldnt be. Thanks in advance

Correct, connecting it doesn't hurt anything.
It's just not necessary.

 

[chrisski]

That's a different sensor than the one used for led acid batteries. Always follow manufacturers instructions. Otherwise you could be voiding the warranty.

That is not a different sensor. I think you’re making things up.

 

[timselectric]

lol
Good luck and be safe.

 

[chrisski]

lol
Good luck and be safe.

How do you get not to use because its unsafe on the BMV 712 temperature sensor out of:

”The cable with integrated temperature sensor has to be purchased separately (part no: ASS000100000). This temperature sensor is not interchangeable with other Victron temperature sensors, as used with Multis/Quattros or battery chargers.”

THere is no mention of not using the temp sensor with the lithium anywhere in the manual.https://www.victronenergy.com/upload/documents/Manual-BMV-700-700H-702-712-EN-NL-FR-DE-ES-SE.pdf

What do you have that makes it unsafe to attach a temp sensor to a battery as per the Victron instructions and use a Victron virtual network to shut off a Victron SCC at a given temperature to prevent charging when the batteries are too cold?

I could be missing something here and if it is unsafe, I’d like to know why. Victron’s documentation might not be the best for some of their pieces, like for example the battery protect or the Orion 70 amp 24 volt to 12 volt converter.

 

[timselectric]

I never said that it was unsafe to use. And I said that you should follow the manufacturers instructions.

 

[rmaddy]

Keep in mind that the Victron BMV-712 does not come with a temperature sensor. That sensor wire is a separate purchase. But if you do get one it is perfectly appropriate for LiFePO₄ batteries. The temperature info can be used by other Victron equipment, such as a solar charge controller, to stop charging when the temperature gets too low.

 

[tmcblane]

Ok so here is where i saw it, it is on my Renogy Rover controller

 

[rmaddy]

When charging LA batteries the charger can adjust the charging based on the temperature. That feature shouldn't be used with LiFePO₄. I've seen that referred to as temperature or voltage compensation.

That's different from using a temperature sensor with LiFePO₄ to discontinue charging if the temperature gets below a certain level.

I don't have any experience with the Renogy product but it might be possible to use it for charging disconnect and not for voltage compensation when applied to LiFePO₄.

 

[tmcblane]

When charging LA batteries the charger can adjust the charging based on the temperature. That feature shouldn't be used with LiFePO₄. I've seen that referred to as temperature or voltage compensation.

That's different from using a temperature sensor with LiFePO₄ to discontinue charging if the temperature gets below a certain level.

I don't have any experience with the Renogy product but it might be possible to use it for charging disconnect and not for voltage compensation when applied to LiFePO₄.

Thanks for the input Rmaddy! this controller can also be used for Lead Acid so you probably have it correct!

 

[timselectric]

Hmmm.......
I guess that I didn't make it up. lol