question

afk314 avatar image
afk314 asked

Cut solar charging in cold weather

Hello,


I have a BMV-712 and a Smart Solar charger. My lithium batteries have an internal BMS which cuts them off from charging at 25F which is too low for my taste. I would like to have the solar charger cut off all charging somewhere around 5C like Victron suggests. What is the simplest way for me to do this?


One idea would be to use a temp sensor on the BMV and then network the BMV to the solar charger. Not sure what cabling I would need to do the latter, but all of this is predicated on being able to configure the solar charger to utilize this incoming temp and cut off charging. I assume this is possible with the Victron Connect app? If not, how else can I do this?


Thanks!

Adam

solartemperature
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3 Answers
mvader (Victron Energy) avatar image
mvader (Victron Energy) answered ·

Hi Adam; welcome.

pls check your solar charger settings in VictronConnect: there is a setting that does exactly this. See here for details of all solar charger settings:

https://www.victronenergy.com/live/victronconnect:mppt-solarchargers


Also; configure the bmv & solar charger together in a ve.smart network. Thenthe battery temp will be communicated wirelessly to the solar charger.

https://www.victronenergy.com/live/victronconnect:ve-smart-networking

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mvader (Victron Energy) avatar image mvader (Victron Energy) ♦♦ commented ·

Herewith a screenshot of the setting in the MPPT:


Note that that 0.1C stepsize will be changed to 1C. The measurement is not that accurate as this setting here implies.

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tinybluehouse avatar image
tinybluehouse answered ·

I've been trying to figure this out too and found that the temperature sensor that came with my BMV doesn't actually work.

So I've sorted this by using a battery protect. On mode C you can use the charge disconnect of the BMS to fire the disconnect between the MPPT and the battery. It uses extra components but the above stuff doesn't work in my experience.

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mvader (Victron Energy) avatar image mvader (Victron Energy) ♦♦ commented ·

Hi; you said the temperature sensor that came with the BMV doesn't actually work: was the battery temperature not visible on the BMV itself?


Or did that part work; but did the MPPT not react (stop charging) when when BMV measured temperature dropped below the threshold that you configured?

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tinybluehouse avatar image tinybluehouse mvader (Victron Energy) ♦♦ commented ·

The temperature was never visible in the first place which is why I went down the protect route

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mvader (Victron Energy) avatar image mvader (Victron Energy) ♦♦ tinybluehouse commented ·

On the BMV you mean? In that case; see BMV manual and instructions for choosing the AUX function (temperature, mid voltage, starter battery voltage)

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tinybluehouse avatar image tinybluehouse mvader (Victron Energy) ♦♦ commented ·

I figured it didn't work as in the app the temp was displayed as "--C"? Do I have to do that in the setup for it to display?

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wkirby avatar image wkirby ♦♦ tinybluehouse commented ·

From the menus it's menu number 69. From there you choose the function of the Aux Input (B2 input on the shunt). Your choices will be START, MID, or TEMP.
From the App, go Settings -> Misc -> Aux Input and choose Temperature

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mvader (Victron Energy) avatar image mvader (Victron Energy) ♦♦ tinybluehouse commented ·

To be honest, I dont know by heart.


What I do know is that we sell 1000s of bmv temp sensors, and there are no issues or ongoing issues. So either you have a broken component or a wiring or config issue. Perhaps a good topic for a separate question here? Otherwise follow the official routr at www.victronenergy.com/support

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tinybluehouse avatar image tinybluehouse mvader (Victron Energy) ♦♦ commented ·

I will try support.

IF that temp did work, would it publish that data via the ve.network which then the mppt could use to shut off at low temps?

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mvader (Victron Energy) avatar image mvader (Victron Energy) ♦♦ tinybluehouse commented ·

yes it will!

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Ben Johnson avatar image
Ben Johnson answered ·

I’m have a similar problem,.. I’ve been searching through the VC forum for the last couple of days and can’t figure out the problem. I just bought my BMV712 and the temp censor wires that came with it don’t seem to be working at all.


I’ve connected the cables with the temp censor on to the positive terminal and im now getting a read out of -1 degrees c. I’ve changed the misc setting to. Aux/temp and still no change. I’ve got a lifepo4 system and don’t want to change my battery with the terminal temp registering that so I got my wife’s dyson Hair-dyer our and heated the terminals where the censor is on the possible side to see if the temperature will read but no luck. I’ve changed the fuses over to 1a blade fuse, as some other people advised on this forum. Some others on here say I need to buy the smart battery sense but seems pointless when it’s part of its basic function.


Any help would be great.. cheers

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