Low temperature cut-off for charging

joe384

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Me again!

I am concerned about my cellink B charging when it is too cold (freezing or a few deg C above freezing).
Realistically, I don't think this would happen as I probably wouldn't drive the car in cold conditions but a couple of mornings the outside temperature has been 4C.

I initially bought a cheap temperature sensor and some 12v automotive switches, with the plan to check the temperature of the battery and switch off the charging before I start the car if it's too cold.

However, it would turn out a bit messy and I may forget! So I am thinking of getting a temperature relay which some people have mentioned here.
The ones on ebay all seem the same design (W1209) and there's a ton of info about them - Would this work ok?

 
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joe384

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I bought one on ebay from a UK seller. I paid a little more (From china they are £2-3!) but i wanted to get it sooner.
It looks like the relay on these is normally open (which is what I want)
If I wire it like below the load should only receive power when the thermostat is working and the temperature is at what is set

511RaUurcWL.jpg
 

Nigel

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The relays on those are connected wrong, yes you just get two terminals that get connected when it turns on, unless you solder onto the unconnected pin on the relay in which case you can have NO/NC.

In the settings, you can switch between on when cold or on when hot, if you set it to on when hot (which is actually the "C" (cold) setting!, then you can set that to 4°C, set the hysteresis to 1°C so that it turns back on at 5°C and set the over-temperature alarm for 45°C (which turns the relay off above 45°C.

At the rate the Cellink charges, I think 5°C is the really safe limit, if you are using a slower charge rate then you can use closer to 0°C, at very low rates you can continue charging down to -20°C, but anything below 0°C is so slow it is not worth bothering.
 
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joe384

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Been very busy so haven't got around to this.

Do you think it's ok to wire it as in the diagram in the previous post? (feeding both from the same fuse tap)

I was thinking maybe I should feed the cellink and the circuit from different fuse taps, is it worth the extra hassle?

w1209.jpg
 

Nigel

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No reason to do that at all, I turned the PCB over and put some solder between the two middle screw terminals so that I only need one 12v cable, and then used the spare screw terminal to power something else since it now has power.
 

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I bought a Cellink Neo 6 and just saw this thread. I didn't see anything specific in the manual about low temperatures. The only limit that I saw was +80 C, where the battery turns off.
Are low temperatures that bad for charging these units?
 

Nigel

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I bought a Cellink Neo 6 and just saw this thread. I didn't see anything specific in the manual about low temperatures. The only limit that I saw was +80 C, where the battery turns off.
Are low temperatures that bad for charging these units?
The specifications for the Cellink Neo 6 do give the charging temperature range:
"– Charging Temperature: 0° − 45°C (32° − 113°F) "
It should actually be 5° upwards given the high charge rate being used.
I did query if there is a low temperature cut off and apparently not, it is up to you.

What happens when you charge LifePo4 batteries in the cold?
Lifepo4 cells catch fire! - Page 5 - Battery Vehicle Society

Now we haven't heard of many fires resulting from a Cellink Neo 6, but given what happens to a car when it burns it would be hard to pin the cause on the battery, so maybe there have been. Personally I don't think it is worth the risk, especially when it is known that even if the batteries don't catch fire, they do rapidly lose capacity if charged below freezing, it is definitely not good for them, which is the main reason most non-electric cars still come with big heavy lead acid batteries instead of lithium cells with everything needed to make them work below freezing - ie internal heaters for the cold and cooling for the hot.
 
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joe384

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I didn't realise there have been any fires from it.

If you have the Neo then you maybe able to check the temperature before starting the car on cold mornings (I'm not sure how the app works)
Or if you use the cigar lighter just leave it disconnected until the car is warmed up.

My Cellink B sits underneath the passenger seat and realistically I doubt it will ever get too cold to cause a problem.
It was -1 the other morning in the UK but inside the car it was probably not as cold
 

DarthMaul

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The specifications for the Cellink Neo 6 do give the charging temperature range:
"– Charging Temperature: 0° − 45°C (32° − 113°F) "
It should actually be 5° upwards given the high charge rate being used.
I did query if there is a low temperature cut off and apparently not, it is up to you.

What happens when you charge LifePo4 batteries in the cold?
Lifepo4 cells catch fire! - Page 5 - Battery Vehicle Society

Now we haven't heard of many fires resulting from a Cellink Neo 6, but given what happens to a car when it burns it would be hard to pin the cause on the battery, so maybe there have been. Personally I don't think it is worth the risk, especially when it is known that even if the batteries don't catch fire, they do rapidly lose capacity if charged below freezing, it is definitely not good for them, which is the main reason most non-electric cars still come with big heavy lead acid batteries instead of lithium cells with everything needed to make them work below freezing - ie internal heaters for the cold and cooling for the hot.
Then I will probably let the battery charge only after it gets warm in the cabin...
Thanks for the heads-up, @Nigel !
 

DarthMaul

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I didn't realise there have been any fires from it.

If you have the Neo then you maybe able to check the temperature before starting the car on cold mornings (I'm not sure how the app works)
Or if you use the cigar lighter just leave it disconnected until the car is warmed up.

My Cellink B sits underneath the passenger seat and realistically I doubt it will ever get too cold to cause a problem.
It was -1 the other morning in the UK but inside the car it was probably not as cold
Yes, the Cellink app displays the battery temperature. The battery will be connected to the fusebox, but I can simply switch the charge current to off (between low and high) until the temperature is suitable for charging. I wish EGEN would add low temp cut-off in a future firmware, if that would ever be possible.
 
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joe384

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I finally got this wired in today. The main issue was just me trying to keep the wires tidy (bit of a perfectionist)
My route to the passenger seat didn't work out (I'd have to remove the seat which I didn't want to mess around with) so the cable going to the cellink is just loose in the passenger footwell for the moment. I have another idea about that but that's for another day.

I gave up on soldering the 2 positives together, the solder on the board was bad quality and I just ended making a mess, so I'm using 2 fuse taps instead.

I was a little worried, initally after switching on the ignition the cellink was flashing green and red.
I realised the voltage may be too low since the engine was not running, so I started the engine and I got the beep and the single charging light.
I think I remember reading the cellink has a low voltage cutoff (pretty sensible now you think about it)

I do think I've gone a bit over the top with this, but hey ho it's almost done now!
 
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