Cheap beginner standalone security light panel/battery that survives freezing temperatures

Hello.

I am just experimenting a little with some old panels I got from some one and I have a hard time finding a answer.

I would like to make one panel charge a small battery bank. I was going for a few used 18650 from old lap top batteries in 3s and wanted to use a very cheap aliexpress charge controler (about 5 euro's including shipping) that supports lithium ion batteries. Even though Adam Welch says they start trickle charging when reaching 4.2 volts and thus are not suitable for lithium ion I would like to to try this set up anyway. I also found some cheap balancer boards but I cannot find any that can stops charging when tempereture drops below 0C/32f. It is my understanding that while trickle charging may reduce battery life a but but charging during freezing with instantly kill the batteries.

I saw some solutions talking about heating pads (50 watts) or even blankets? But those are for big size solar setups or car batteries they heat up just before use but they use the utility grid for that. What about all those solar solutions I see next to the road/highway. A panel on a pole with some sort of box below it. Or the panels on
buoy's in the middle of lakes and rivers. Do they all have enough solar power to keep their batteries heated I cannnot image that to be true.

My question is , what kind of simple and cheap setup is normally used for small off grid solar solutions that have to power al small light or blink a buoy or something all year round?

Regards


Hans

I think the idea with heaters is so that the batteries stay operational during cold weather. But, if you just want them off or as a safety if the blankets fail, there are temperature switches. I don't have a recommendation but I know farmers need them to turn on/off devices at freezing temperatures. You just need one for your voltage/current if no one comes back with devices they can recommend you might try googling "12 volt temperature switch" or "12 volt thermostat switch". For example, here's a 12V 10 amp temperature relay for $6 (not a recommendation, might be junk for all I know).

Hi Svets,

Thank you for your reply. I would prefer if things just kept working but I think that is out of reach for low budgets so blocking the charge would be the next best thing. With the climate changes we hardly get any freezing days anymore anyway.

Yes I have been looking at these temperature relays they are cheap! But it is it not clear to me if they can turn also of based on a minimum temp. They all seems to turn off at at a max temp. The decription of this one states: "High temperature protection: 0 ~ 110°C" nothing about low temperature protection. They other worry I have is what if the battery runs out of power? Will it remember iets settings when the power comes back?

I have these worries because I was messing arround with this budget solar charger and old lead acid start battery (65ah) . During the day it charged the battery. At night I had a 10 watt light bulp connected to load. I had the low voltage cut off at 10.7. Which it did. But the charge controller needs power for it self too and apparently it was just a little too much (I gues cloudy days) so the battery went bellow 10.7 and in the end the solar box became in a sort of crashed state from which it did not recover the next day when the sun came up. It it did not even charge the battery. I had to disconnect every thing and reconnect for it to come back alive again.
I tried it with one hour shut off after sundown and it worked fine the battery did not get drained that much so it could power the charge controller all night. Yes I know it was a very cheap device.

So I need the temperature relay that block charging when it has no power. Like when in doubt do not charge.

An example of a cool gadet is this 3 Bay 18650 Lithium Battery Charger MPPT. I doubt if it is mppt but it takes a solar panel and charges 3 18650 does balancing and over and undercharge protection so you can put it is a small box attach a led and hang it in a tree or something. I really like it but every thing seems spoiled because what happenes when it freezing?

But there must me many solar powered sheds out there that get below 0c (or 32f) every year? How are they suriving? Or is it back to lead acid for these situation?