Batteries and Temperature Ranges

[DigiTan]

I'm in the process of starting another theft-deterrant system and I'm at the stage where it's time to order components. The design needs to be reasonably rugged so the logic circuits are favoring industrial-grade components over the usual commercial grade. One problem that stuck out was the battery spec., which warned against operating near freezing temperatures. There is not much room for battery insulation, so basically I'm on a hunt for a rugged battery.

Basically I have three questionss:
1. What are some typical max/min temperature ranges for (non)rechargable battery types?
2. Is there a particular battery type or brand that is resiliant in sub-freezing conditions (as low as -20°C)?
3. Besides what are the electrical consequences of operating a typical battery at very low temperatures? (current loss? shorter lifespan? lower capacity?)

 

[Thunderchild]

may i ask where u intend to go with this alarm system 20 °C ?! :!: :?:

 

[Optikon]

I'm in the process of starting another theft-deterrant system and I'm at the stage where it's time to order components. The design needs to be reasonably rugged so the logic circuits are favoring industrial-grade components over the usual commercial grade. One problem that stuck out was the battery spec., which warned against operating near freezing temperatures. There is not much room for battery insulation, so basically I'm on a hunt for a rugged battery.

Basically I have three questionss:
1. What are some typical max/min temperature ranges for (non)rechargable battery types?
2. Is there a particular battery type or brand that is resiliant in sub-freezing conditions (as low as -20°C)?
3. Besides what are the electrical consequences of operating a typical battery at very low temperatures? (current loss? shorter lifespan? lower capacity?)

Is the battery your only power source for your design? If it is NOT, consider warming the battery. A low cost temperature controller can be made to warm the battery if the ambient gets too cold. This way you dont have to buy some exotic (read expensive) grade battery.

The chemical reactions slow down inside of a battery at colder temperatures. So I would imagine this pretty much degrades many of its specs. But I dont know that for sure. You ought to follow the manufacturers guidelines and temperature ranges since they know their chemistries the best.

Look at using lead acid batteries like the automotive market does. The most "rugged" battery technology you will likely find will be lead acid. I fyou can afford the power drain, let it warm itself a little bit. You may find that just 5 degrees warmer than a -20 ambient does wonders to the specs.

 

[DigiTan]

may i ask where u intend to go with this alarm system 20 °C ?!

Well, there are two variations of this system. The existing one is for indoor conditions and its counterpart is for the automotive setting. To cover all the climates in this region, it needs to tolerate -20C for hours at a time (worst case). This battery is used when external power is removed or sabotaged, so it absolutely, positively must be self-contained.

Is the battery your only power source for your design? If it is NOT, consider warming the battery. A low cost temperature controller can be made to warm the battery if the ambient gets too cold. This way you dont have to buy some exotic (read expensive) grade battery.

Okay this sounds like a good strategy. I have at least one lead acid cell that can fit the spec without major changes to the system. Perhaps I could use some kind of a thermister to activate this heater in a certain temperature range. What is a good method for this kind of low-power heating (special wire?)

 

[Thunderchild]

well then the battery can be heated by the "normal" power source and i should think that it will auto heat itself when it is used.

 

[Optikon]

may i ask where u intend to go with this alarm system 20 °C ?!

Well, there are two variations of this system. The existing one is for indoor conditions and its counterpart is for the automotive setting. To cover all the climates in this region, it needs to tolerate -20C for hours at a time (worst case). This battery is used when external power is removed or sabotaged, so it absolutely, positively must be self-contained.

Is the battery your only power source for your design? If it is NOT, consider warming the battery. A low cost temperature controller can be made to warm the battery if the ambient gets too cold. This way you dont have to buy some exotic (read expensive) grade battery.

Okay this sounds like a good strategy. I have at least one lead acid cell that can fit the spec without major changes to the system. Perhaps I could use some kind of a thermister to activate this heater in a certain temperature range. What is a good method for this kind of low-power heating (special wire?)

You want cheap? A thermistor, couple resistors, a comparator, a power transistor and a power resistor. Wire up th ethermistor and resistors for a trip point on the comparator(with hysteresis). The thermistor should be placed to sense ambient temp and not near the battery temp. Have the comparator switch the power transistor to burn power in the power resistor. Put the power resistor near the battery with good thermal conduction to warm it. If pretty crude is all you need I bet you can get it to keep the battery upto 10 degrees warmer than ambient.

Of course if this will not due, you can always go more elaborate with temp sensors & PID controllers to servo the battery temperature. That may involve a good heating method like nichrome wire or something similar.

You could make your power heating resistor a distributed one by dividing it up into many smaller ones ditributed around the battery but you'll have to work out the details.. This kind of think would work well on a smaller type battery if yours is physically huge, it might not be suitable/practical.

 

[Optikon]

may i ask where u intend to go with this alarm system 20 °C ?!

Well, there are two variations of this system. The existing one is for indoor conditions and its counterpart is for the automotive setting. To cover all the climates in this region, it needs to tolerate -20C for hours at a time (worst case). This battery is used when external power is removed or sabotaged, so it absolutely, positively must be self-contained.

Is the battery your only power source for your design? If it is NOT, consider warming the battery. A low cost temperature controller can be made to warm the battery if the ambient gets too cold. This way you dont have to buy some exotic (read expensive) grade battery.

Okay this sounds like a good strategy. I have at least one lead acid cell that can fit the spec without major changes to the system. Perhaps I could use some kind of a thermister to activate this heater in a certain temperature range. What is a good method for this kind of low-power heating (special wire?)

Its not necessarily "low power" heating.. low power heating usually means "low heating" If you've found a battery that meets the spec, consider not heating it at all. Put it in the freezer and see how its capabilities are diminished. If it works, why do anything extra?

If you need to heat then it,then you have a thermal design challenge that you'll have to work out how to achieve the desired result.

 

[Joel Rainville]

it needs to tolerate -20C for hours at a time (worst case).

You have it easy. A worst case scenario up here would be -40C for a few days! :shock:

 

[zevon8]

At work we have some AA size lithium batteries that live outdoors all year round, ( -20C and well below that temperature.) In fact, we have to heat the LCD display on the device so it works. Don't know what kind of load you need to supply, but it's an option anyways.

 

[DigiTan]

Oh, that last part brings up another question I forgot to ask. Are there any LCD dot matrix displays designed for freezing environments? -20C may be too much to ask for, but for now I'll take anything. If there aren't any, I can switch to alphanumeric LEDs.

 

[zevon8]

The heaters we use are made just for LCD displays. I believe they are ceramic. There are lots of types anyways, some are clear, others are glued to the back. They are self contained, automatic devices, just connect them to a power source.