Battery monitor suggestions?

_OS_

I am considering exchanging my Trimetric battery monitor with one that compensate for battery temperature and wonder if anyone have any recommendations?

I have searched the net and the Xantrex LinkPRO seems like a very good choice. Does anybody have any experience on this one?

Thanks!

Ole

icarus

Re: Battery monitor suggestions?

Ole,

Since the Tri-metric is only a monitor, does it really make any sense to change it out for the few days a year you are there in the cold? Since the Trimetric only reports data, and doesn't control any thing, you are free to interpret the data, taking into account the expected effect on battery temperature.

The reality is if you spend time there in the winter, the batteries will warm up as the house warms up, plus they will warm up due to charge/discharge self generating heat.

My batteries can (and do) get very cold if I leave the house for a couple of days, and it takes days for them to warm up, but the Trimetric just plugs away

I think this is a solution in search of a problem.


Tony

boisblancboy

Re: Battery monitor suggestions?

If I remember right his batteries are stored out in the shed, not in the house. Not being an expert I wouldnt have any idea how much they would warm up from just the use while being in the cold.

icarus

Re: Battery monitor suggestions?

You may be right,, I have a vauge memory on another thread that the batteries are in a shed. Batteries in an insulated box will pick up several degrees F from self generated heat. One set of my batteries in a closed shed in an styrofoam insulated box. They can be easily be 10 degrees warmer than outside.

Tony

boisblancboy

Re: Battery monitor suggestions?

I would think that if you were going to leave your batteries outside in the cold would the batteries have a longer life if they were in something insulated?

Also, here is his previous thread, might jog your memory some more:

http://forum.solar-electric.com/showthread.php?t=3154

icarus

Re: Battery monitor suggestions?

Battery CAPACITY goes down with temperature while longevity goes up.

Batteries are generally rated at ~77F, For every 15F above that temp battery life is diminished ~50% if memory serves.

http://www.batteryfaq.org/

"Even though battery capacity at high temperatures is higher, battery life is shortened. Battery capacity is reduced by 50% at -22 degrees F - but battery LIFE increases by about 60%. Battery life is reduced at higher temperatures - for every 15 degrees F over 77, battery life is cut in half. This holds true for ANY type of Lead-Acid battery, whether sealed, gelled, AGM, industrial or whatever. This is actually not as bad as it seems, as the battery will tend to average out the good and bad times. Click on the small graph to see a full size chart of temperature vs capacity." from:http://www.windsun.com/Batteries/Battery_FAQ.htm#Lifespan%20of%20Batteries

Tony

boisblancboy

Re: Battery monitor suggestions?

So couple questions come to mind:

With colder temps and longer life, does that life mean more cycles? Could you go deeper, 10-20% more with each cycle since you would have less capacity with the colder temps?

Any problems charging at a battery at very cold temps?

BB.

Re: Battery monitor suggestions?

Gets even more complicated... The specific gravity of the acid/electrolyte drops (to 1.0) and the batteries will freeze near 32F / 0C.

You shall never charge a frozen battery. AGM's are better when freezing. A flooded cell battery will crack the case.

-Bill

boisblancboy

Re: Battery monitor suggestions?

Yeah I know that lead acids when their charge drops will freeze, I have seen that many times.

Anyone know of any graghs showing the different types of batteries and COLD temps?

icarus

Re: Battery monitor suggestions?

Point in fact, a well charged battery won't freeze until way past -40
A 100% charged battery won't freeze until ~minus77f! 75% soc -35, 50% -10f.

http://www.batteryfaq.org/

I really don't want to be out an about at -77. I have seen -58F, and often see -40F.

Tony

BB.

Re: Battery monitor suggestions?

Because, as I understand, AGM batteries use a glass mat to hold the electrolyte next to the plates--instead of a liquid column of electrolyte--there is room for the ice crystals to form/expand without cracking the cases.

However, you still cannot charge them while frozen.

-Bill "I see hard freezes about once every 15 years" B.