Max temperature rating for a battery?

cizzi

I have an 8GU1 gel battery I wish to use for an outdoor application, it can get up to -30C here in montreal canada. Would the battery be able to perform under those conditions?

BB.

Re: Max temperature rating for a battery?

You can store the battery at 100% charge that cold--but if you start to discharge it, the acid strength (specific gravity) drops (100% discharge, electrolyte is basically water and will freeze at 0C/32F).

Keeping the battery "warm" (insulated box and/or buried in ground) will help keep the batteries from freezing, and also give you more useful energy (cold batteries do not deliver near as much power).

Lastly, if there is a chance of freezing, I believe AGM sealed batteries are the only ones that will not be damaged by freezing (however, they cannot deliver energy or be charged if frozen).

Will you be there to watch the battery temperatures (i.e., hunting/vacation cabin where you can monitor the batteries to see if the conditions are OK for use) or does this need to be automated and "bullet" proof (i.e., remote radio repeater station).

-Bill

cizzi

Re: Max temperature rating for a battery?

Well I plan to build a post about 8-12 feet tall in my backyard, to the top i will attach 2x15watt panels, then will install a light and a camera that works on 12vdc and sends the video somehow via 2.4ghz or other means (didnt decide that part yet). So somewhat independant as it will be hard to go deep in the backyard with 5 feet of snow in our worst case.

icarus

Re: Max temperature rating for a battery?

Use an Ice Chest/cooler for a battery box. Battery in the cooler, buried under the snow, will not freeze under those conditions, assuming there is some charge in the battery.

Icarus

cizzi

Re: Max temperature rating for a battery?

can i put a charge controller in the ice box as well?

icarus

Re: Max temperature rating for a battery?

Don't know why not, assuming it is dry.

Tony

cizzi

Re: Max temperature rating for a battery?

was looking at morningstar's cheapest PWM controller.. its rated for outdoors up to -40C so its perfect for my application and 2x15 amp panels.. but it says its best for 1 panel only, dont see why 2 in parallel wouldnt work since its good up to 4A or so.. its the "Morningstar SunGuard SG-4" model

crewzer

Re: Max temperature rating for a battery?

From Bill Darden's Battery FAQ's: http://jgdarden.com/batteryfaq/carfaq4.htm#freeze_points

However, expect effective capacity to be reduced by ~1%/degree C ref 25 C, or by ~50% or more at -30 C. See: http://www.lifelinebatteries.com/rvgraphs.php

HTH,
Jim / crewzer

niel

Re: Max temperature rating for a battery?

cizzi,
i'm somewhat concerned with the total load being drawn by the camera and transmitter going 24/7 if the pvs you have will supply enough of the power to prevent the battery being drained off and possibly freeze. i didn't look up the battery, but you must be sure it won't go below 50% dod either for battery life and with lessened capacity due to cold temps the load could represent far too high of a load over time and drain off your battery.
that controller would need to be with the battery in the same environment, but protected from possible shorts and possible damages resulting from battery aging, failures, acid mist (for vented lead acid batteries), etc.

mike95490

Re: Max temperature rating for a battery?

niel wrote: »

cizzi,
i'm somewhat concerned with the total load being drawn by the camera and transmitter going 24/7 if the pvs you have will supply enough of the power to prevent the battery being drained off and possibly freeze.

Ditto.
you need to find out how much power you need to supply to the cam & xmitter. You may do better to run a 500' AC power cord to the site, than to build up a "monster" solar system for $900, that a $20 cord could do. You can still use wireless to get video back, but consider a power cord?

cizzi

Re: Max temperature rating for a battery?

The whole project is to use solar only power, if current draw is an issue I will look into devices that use very low and activate on movement only to limit draw. Thanks for the heads up.

mike95490

Re: Max temperature rating for a battery?

cizzi wrote: »

The whole project is to use solar only power, if current draw is an issue I will look into devices that use very low and activate on movement only to limit draw. Thanks for the heads up.

Find the power draw of your cam/xmitter, and then we can advise Battery / PV to power it.

cizzi

Re: Max temperature rating for a battery?

I know how to calculate based on requirements, I will do my own math. Thanks. My orignal question was on the gel battery (8gu1) being outside.

niel

Re: Max temperature rating for a battery?

cizzi wrote: »

I know how to calculate based on requirements, I will do my own math. Thanks. My orignal question was on the gel battery (8gu1) being outside.

that is why i brought this forward about the drain on the battery over time because being outside and cold you have a diminished capacity and therefor a diminished 50% dod point resulting in far less usable power from the battery before the battery life suffers.

ps-pm me on where you get your cameras and what kind of luck you have with them.

mike95490

Re: Max temperature rating for a battery?

cizzi wrote: »

My orignal question was on the gel battery (8gu1) being outside.

Looking at the freeze chart http://www.jgdarden.com/batteryfaq/carfaq4.htm#freeze_points and estimate how cold your battery will be, at 6am, after running down all night. 30% discharged, 60% discharged if the previous day was cloudy ? The lower the state of charge, the warmer the freeze point is, and if it does freeze, you MUST thaw it before recharging, and your charge controller will not be able to calculate that. At least with the AGM, you won't have to worry too much about gas, or freeze damage. Since they ARE so efficient at about 95%, you won't get a lot of heating inside the ice chest from them. 600W daily into the battery gives you about 30W of actual heating, spread over the solar day. You may get a bit more heat from the actual charge controller, so the battery may get pretty chilly. Maybe include a remote battery thermometer in your camera package.

cizzi

Re: Max temperature rating for a battery?

i was thinking of building an isolated wooden box and the place a cooler within the box as well, since its a gel battery there's very little gassing and i could make a few holes for vent in case.. put the whole thing with a hinged door and lock.. should help with the temperature

cizzi

Re: Max temperature rating for a battery?

After more searching I found this on google about the battery I intend to place outside for my custom built light pole in the backyard.

"12V 31Ah (20hr) Sealed GEL
The gelled electrolyte won’t stratify, so no equalization charging is required. Less than 2% per month standby loss means low discharge during transport and storage. Gel batteries are best for cycling operations and where very cold temperatures are expected. They can operate at temperatures from -76 to 140 Fahrenheit."

The key words here is from -76F TO 140F.. now -76F is about -60C and the coldest it will ever get here in montreal is -30C. Now to make things better if I use very little power to keep my battery full (i.e 12vdc LED lighting) I think I will be fine.

mike95490

Re: Max temperature rating for a battery?

Gel battery vs AGM.

I know nothing about gel, but do know that 31 AH is very small, and you, with solar, are likely going to need a battery capacity of maybe 200AH, and solar PV for charging it (300W?)

Get your loads figured out before you purchase any gear.

AGM batteries - many claim to be "freezable", but must be thawed prior to recharge.

The claim for freezeable Gel batterys is suspect:
http://www.mkbattery.com/techref_faq.php#hmefaq5
A: MK Gel batteries can be stored in sub-freezing temperatures as low as -25°F without freezing as long as they are fully charged prior to storage. The self-discharge rate of fully-charged batteries is so low in these conditions that they will not require charging for many months; however, if your gel batteries are frozen … they will not always recover.

To attempt recovery the following is the best plan of action:

1) Bring them inside and let them sit at room temperature for two days. (They must reach 60°F).
2) Charge the batteries normally. (Follow standard safety procedures).
3) Run a capacity check either through a quality discharge tester or by operating your power wheelchair in a controlled environment.
4) If you don’t get enough run time then repeat steps 2 and 3.

cizzi

Re: Max temperature rating for a battery?

I'm not purchasing any gear, I'm making use of what I have to adapt it to my project.

niel

Re: Max temperature rating for a battery?

what is the total ah drawn over the 24hr period? does this battery fit that 24hr draw (maybe more for cloudy periods and backup days) so as to not go below 50% dod? it would depend on each camera's draw and of course the transmitters too. if going with 1 typical cheap b/w camera and transmitter this should be about 200ma and over 24hrs this is about 4.8ah and should be well within your battery's abilities at about 15.5% dod and 31% dod if for a day's backup. if there's more being drawn by it being color, higher quality, and/or with ir leds this draw could possibly triple and exceed the 50% dod point based on standard operating temps and not -30 c. personally, i don't like the led models as they draw too much power. i have a quality color camera that just about sees in the dark without leds down to .002lux with dsp. it draws about 250ma by specs and i haven't measured it yet, but i know this specs equal to or better(emphasis better) than most led models. you do pay much more money for cams like that though.