Batteries for small solar system- advice needed

[BAK]

I just bought a 45 watt solar kit from Harbor Freight. Next step is to get some deep cycle batteries to store all that solar power. From my research, regular deep cycle gel batteries degrade over time unless they are constantly charged. Since these batteries will be used only for emergencies purposes, it doesn't make sense to have them charge non stop for years. What are the alternatives?

I remember JWR mentioning in his book that you can get dry batteries- meaning the battery acid or distilled water in some cases has not been added to them and I can add it when I actually need to use them. Any body has any experience with that? How complicated is that?
Any advice will be appreciated

[tech]

Dry charged batteries are an effective way to have fresh batteries on hand when needed. They are, however becoming a bit more scarce than in the past. ONLY add acid (electrolyte) of the correct percentage - adding straight distilled water to a dry charged battery is no good.

It is simple to add electrolyte - provided you use proper safety equipment. Acid-proof goggles, rubber gloves, rubber apron, acid-rated respirator, well ventilated area and good lighting...the usual suspects :) Don't use aluminum funnels or tools as the acid will quickly damage them. A pre-mixed container of baking soda and water should be nearby to neutralize any acid spills.

HTH!

[SeldomSeenSlim]

With a panel that small, you won't get much storage. Batteries consume themselves. It's the reason why if you leave a car sitting for months without starting it, the battery will be dead. The rate in which this happens depends on the size and style of the battery. The bigger the depth of the cycle a battery can handle, the more the battery consumes itself.

I use a 35 watt panel for my gate opener. It's just enough to keep the battery topped off and to recover from the use of the gate. Those small panels would be good to charge a laptop (laptops take ~80w so it would have to be off), cell phones, rechargeable batteries (AAA, AA, C, D), handheld radios, and other really small things. I have another small 90 watt panel for extended hunts. I connect it to one of the truck batteries so I can charge dog collars, radios and such off the truck without having to start the truck or worry about draining the batteries and it not starting. Those small panels are really more for "point of use" and trickle charging than anything else.

[tech]

Never heard of a battery consuming itself. Not unless you count short-circuiting the lithium battery packs that were in the old PRC-77 radios.

The reason a car won't start after leaving it sit is due to parasitic drain - the memories of the radio, the clock and the computers all take a very small amount of power to maintain. Some manufacturers claim that up to a two amp draw is acceptable. Bad diodes in the alternator or a bad/dirty battery will drain a battery quickly, too.

[trkarl]

I think what was meant by "consuming itself" is that it self discharges over time.

[SeldomSeenSlim]

I think what was meant by "consuming itself" is that it self discharges over time.

Yes, I think that's a better way to say it. The chemical reaction that allows a battery to discharge happens whether or not power is being drawn out.