Battery type for rough weather conditions - Page 1
Forum section: electronics / projects

author: j3h4
author_rank: Newbie
timestamp: December 20, 2011, 09:47:46 am
content: Hi, I am a hobbyist and designing a solution which is going to be outside all year around in the Danish weather. So the temperature will vary between -20 degrees C (-4 degrees F) to 30 degrees C (86).What is the battery type best suited for this? I hope for some kind of rechargeable...

author: Psi
author_rank: Super Contributor
timestamp: December 20, 2011, 10:12:53 am
content: What kind of current/voltage/capacity do you need?

author: ejeffrey
author_rank: Super Contributor
timestamp: December 20, 2011, 10:25:15 am
content: I think lithium primary cells have good performance across high and low temperature. The lithium ion/polymer cells I have seen are rated down to -20 C, but I don't know how much the capacity and max discharge rate drop. Normal alkaline batteries are crap, as are rechargeable lead acid and NiMH batteries. 30 C is not high temperature so any battery should at that temperature with no problem. If you have high discharge rates the internal temperature may get much higher.

author: ipman
author_rank: Regular Contributor
timestamp: December 20, 2011, 10:25:30 am
content: On such cold weather, all kinds of batteries will have some problems anyway.The lithium-based batteries will handle better lower temperatures, but .... still, we don't have enough input data to recommend something.

author: Psi
author_rank: Super Contributor
timestamp: December 20, 2011, 10:29:09 am
content: Quote from: ipman on December 20, 2011, 10:25:30 amYeah, that's what i was wondering about the capacity he needs.Maybe one or two ultra capacitors would be more suitable.There lifespan would be way longer too. Probably forever.Downside is you need to design a SMPS to handle their change in volts as they discharge, since they don't have a nice flat area like batteries.And of course less capacity, 5 Wh/kg vs 40 Wh/kg for a lead acid.That's not always an issue though, if you only need a small amount of energy or have room for extra ultra capacitors.Large trucks in cold regions use ultracapcitors in parallel with their lead acid battery to provide starting current when the whole truck is at sub zero and the battery performance is awfulNot to mention the oil is as thick as molasses so turning over the engine isn't easy.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: December 20, 2011, 11:39:21 am
content: You should check about YUASA YTZ series, special made for snowmobile and Jet-ski, and motorcycles.But they are costly.

author: Slobodan
author_rank: Regular Contributor
timestamp: December 20, 2011, 02:59:21 pm
content: Bare in mind that, If it is in direct sunlight, although the air temperature is 30 degrees, inside the box, where the battery is, temperature can be much higher.

author: bfritz
author_rank: Regular Contributor
timestamp: December 20, 2011, 05:21:33 pm
content: Quote from: j3h4 on December 20, 2011, 09:47:46 amFirst, your high temp should not be a problem for most cells. For any cell you will want a ventilated battery box of some type, and a way to make sure the cells and battery box are not heated by the sun in warm summer months.Lithium Thionyl Chloride cells do quite well at low temperatures. There are not many manufacturers, and they will likely only be available to you, if you have safety circuitry designed by someone approved by the manufacturer. I would not recommend Lithium Thionly Chloride to a hobbyist, as you will likely have great difficulty trying to buy the cells from any manufacturer. There are a greater number of safety concerns with them than Li-Ion. I'll give some representative numbers for D size cells. Li/SOCl2cells are of a couple basic types, bobbin and spirally wound.The bobbin type have about 19Ah capacity, 720Wh/kg, 1270Wh/L. The bobbin type cells are much safer, but are rate limited to about a C/100 rate. At fully charged cells are typically 3.65V, midpoint voltage is 3.3-3.6 depending on the manufacturer, and end voltage of 3V. At -30C expect to get only about 50% of the capacity of the cell.The spirally wound type have higher drain rates, but can experience some serious problems if not treated well. You've probably seen these used, as this is the battery type used in the space suits of the American Astronauts for the shuttle missions. Capacity of 13Ah, 455Wh/kg, 860Wh/L. The discharge characteristic of these cells is incredibly flat. At the lower rates you will get the full rated capacity, and as rates go up to about C/10, you will get about 8.6Ah.Unless you are ready to spend sizeable amounts on safety circuitry, and really need the performance of Li/SOCL2I'd recommend cylindrical Li-Ion. For a hobbyist this is the practical choice.The most common size for Li-Ion cells is the 18650, so named as it is nominally 18mm in diameter, and 65mm in length. The "Energy" versions, most commonly used in portable computers and other consumer electronics, have higher capacities. The "Power" versions, most commonly used in tools, have higher current rate capability. The data on the various types is pretty available at the manufacturer web sites. For a Li-Ion at -20C, about 85%-90% of the energy is available, but will be at much lower voltages than when the cell is at 25C. For such low temperature discharge expect the midpoint voltage to be at 2.75 - 3V, rather than the 25C midpoint of 3.7V.

author: McMonster
author_rank: Frequent Contributor
timestamp: December 20, 2011, 05:32:41 pm
content: I would throw the device into a case filled with mineral oil like in this construction:https://www.adafruit.com/blog/2011/10/23/ridernet-v2-an-all-weather-arduino-managed-wifi-network-for-horses-and-ponies/

author: Neilm
author_rank: Super Contributor
timestamp: December 20, 2011, 07:53:19 pm
content: You state that the unit will be left out all year round, so I assume that it will be charged when it is outside. If you wanted to use Lithium, you will have problems charging them below freezing unless you get some quite expensive cells - I believe that the military use some that can be charged that low at restricted current.I have used YUASA lead acid in applications that work at this sort of temperature.Neil

author: Zero999
author_rank: Super Contributor
timestamp: December 22, 2011, 09:40:39 pm
content: Quote from: j3h4 on December 20, 2011, 09:47:46 amPlease provide more information: voltage, capacity, discharge/charge current etc.NiMH will be fine for discharge down to -20oC as long as the rate is <1C. All' the the datasheets I've read, apart from Duracell's give minimum temperatures of 0oC for a standard charge but I suspect a trickle charge of <0.05C will be fine.http://www.farnell.com/datasheets/1314038.pdfhttp://www.rapidonline.com/pdf/18-4037.pdfhttp://docs-europe.electrocomponents.com/webdocs/0df1/0900766b80df1956.pdf

author: Psi
author_rank: Super Contributor
timestamp: December 22, 2011, 11:48:10 pm
content: For comparison, a maxwell ultracap will work down to -40deg C and up to +65deg Chttp://www.maxwell.com/products/ultracapacitors/docs/DATASHEET_K2_SERIES_1015370.PDFAt -40 its ESR is 175% worse than normal. However its normal ESR is so ridiculously low anyway (0.8mR) that 175% at -40 is only 1.4mR.(A typical lead acid is 20-50mR at room temp)Capacity wise, at -40 deg C it's 95% of normal, so no issues there.Above about 0 deg C the capacity and ESR are pretty much normal.Lifespan is 10 years at room temp or 1500hours at +65degC (before capacity has fallen by 20%)I'm not sure about their self discharge rate. I tried to do the math on the 650F one in that datasheet and came up with 13days, but i'm sure that's wrong since my ultracaps stay charged for months. (Leakage value in that datasheet might be absolute worst and not a real world value)

author: j3h4
author_rank: Newbie
timestamp: December 26, 2011, 08:39:40 am
content: I will do some measurements. The circuit will be based on an Attiny85 running in sleep mode most of the time. Periodically it will wake up, do some measurements and transmit them with an RF circuit. The battery will be charged with solar power. The Attiny will be running at 3.3v and the RF circuit will be running at 12v