Battery test

[CI_Guy]

I work for one of the big box retailers. A co-worker over in electrical, who is an avid bass fisherman, was fasinatated by all of the battery storage theories he read on the BFHP boats and motor message board. He was amused by the deap south bassers who had moved a few states north and were worried about thier batteries surviving a week or so of sub 32*F weather. He had puchased a new set of Interstate series 27 batteries for his 24 volt trolling motor last March. He decided to use them in a test of 2 diferent storage methods. In late Oct. he charged both batteries with his guest onboard charger. He then added a small amount of needed water to each battery. 2 days later he topped them off with another charging. He tested them with some sort of meter that showed both batteries were charged to a little over 95% capacity. He disconected the wires from them and left one in the boat, that was in unheated storage, the other battery he stored on a piece of wood in his utility room. On April 15 he got his boat out of storage to prep it for the Mn. walleye opener. He tested both batteries with the meter before hooking them up. Neither battery had been charged over the winter. The battery from the boat tested at a little under 80% of capacity. The battery that had been stored in his house tested at a little over 60%. He assumes that becase cold slows down most chemical reactions, the cold stored battery did not discharge as fast. The only thing that suprised him was that the battery stored inside was a little lower on water than when he put it away last fall. It was probably evaporation through the vents in the battery due to low humidity in the house. He hooked the batteries up and charged them with the onboard charger. They both charged up to over 95% again. He went crappie fishing for a few hours on Tues. After the trip the 2 batteried tested within a couple of ticks of each other on his meter. He plans on continueing this storage test for the life of the batteries to see which one fails first. The results of this 1st winter looks like both methods have the same result. Sorry for the long post, but after all the battery talk on WC last fall I thought you may find this interesting. Pat K

[Mr T]

It is interesting and a very good post. I for one, would like to be updated as to what you guys find as the month's go on.Winter battery storage is always an issue with us Walleye guys who run 3 to 5 batteries in our boats.

[Mike]

A car battery drains faster when it's cold Why wouldn't a deep cycle battery do the same?

[Hawgeye]

A car battery seems to drain faster when cold but actually it is due to higher amperage draw from the equipment it is trying to run. Starters on cars draw much higher current in the winter because the oil in the engine is stiff and thick, the grease on all parts is stiff and thick and everything like belts and things are much stiffer. According to the Interstate battery representative, store batteries in a cool place. Batteries deteriorate faster in warmer temperatures than cooler temps. Of course when we get to below zero, that theory no longer holds true. I think interstate batteries may have a website that may describe this. I will post later if I find more information on this...

[REW]

Actually this is smoke and mirrors as far as the drain is concerned.

The original post is right on. Batteries are electro chemical devices. They generate electricity with a chemical process. The colder the battery and chemicals, the slower the process occurs.

This is also part of the answer to the post about the batteries in the cold.

Because of this same chemical action, the battery at -20 will be capable of sourcing less energy, than if the battery is at +80. i.e. slower chemical process, less electricity.

The other reason that then battery drains faster, is that as the previous post suggests, all of the loads in the winter cold are greater than in the heat of the summer. So a starter that normally spins your engine in the summer might use 100 amps of starting current. However, if the temp is -20, the starter might be drawing 250 amps of current to try to spin the same starter, and this is with a battery that is only capable of supplying about 70-80% as much energy as in the summer. This is the reason that the cold drains the batteries more quickly, based on starter spin time.

Take care

REW

[mlc]

Good experiment. I predict that the battery stored inside will last the least amount of time. The reason for this is that it discharges faster(impurities in the battery cause an actual current flow within the battery even when not hoooked up. This is called "internal action")due to warmer temperatures. Batteries should be stored for extended periods with as close to full charge as possible. A process called sulfation occurs when a battery is stored for long periods of time at less than full charge.

A suggestion for the next set of batteries he uses would be to store using the method derived above, but charge the batteries once per month during the storage period. This will really add to the life of the batteries.

Please keep us posted on the results.

mlc