Power Tanks

[trogre]

Hi All. Just going through different parts of the forum and came across the topic on power tanks.

I use a leisure Battery occasionally for powering up a small pump. The battery shop I purchased this from told me it was essential to put it on charge when I finished using it. He said that it will continue to discharge even though it is not in use. Failure to charge straight away will shorten the life of battery considerably. Naturally I never did this!! And the battery will not hold its charge for more than a few days and less than a year old.

Not sure if this is peculiar just to leisure batteries or all batteries. It is worth checking out as a power tank may due to weather get use for say one hour then not again for a few days or a week or so, weeks if 2012 weather is anything to go by. This may of been covered somewhere in another thread but I am slowly going through as many as I can even if old subject. I also suspect and again may of been covered that the actual battery can be changed rather than buy a new unit. May save e a lot of heartache

Funny I am one of those that will strip something if it is broke and needs replacing, just to see the innards. Once had a car battery charger die on me so purchased another one. The case of the old charger was pop riveted so unless you wanted to take time to drill rivets out you just binned the charger. Once inside the charger I was amazed to find a small fuse and this had blown. Cost a few pence to replace, put case back on and it went on for a few more years. The manufactures do not want you to do this so you will spend more money on a new unit, always worth checking something out before you bin it even if you have purchased a new product.

[ronin]

The "Power tanks" are small standard lead acid batteries and the reality is they are not the right battery for the purpose they are applied to in astronomy. Does make you wonder why they are sold as such therefore.

I would check what a "Leisure battery" actually is - I have the impression they are a bit of a hybrid but are really a lead acid that is sort of "beefed up" and that is hoping to get away with doubling up as a deep cycle.

Leisure batteries are often referred to in camper van applicartions and when in one they are charged from the alternator which is unsuitable (I think) for charging a deep cycle battery.

A standard or standardish lead acid battery will discharge over time and the low charge causes problems and death of the battery.

[perfrej]

Three basic type of L/A batteries:

Standard car batteries. Electrolyte is in liquid form. This cannot battery is ruined the split second you drain it below 11.5V.

Gel batteries. Electrolyte is in gel form which sticks better to the lead plates. A good leisure battery is gel. They are more tolerant to discharge, but do keep in mind that the battery is still drained when you go below 11.5V.

AGM, or Advanced Glass Mat, batteries. The electrolyte is in a fiber glass mat. These batteries can take just about any beating in terms of discharge. I have drained a couple of AGMs down to 0.0V measured unloaded and they are fine after that. Price is almost twice of a standard car battery.

For astro work, AGM or a really high quality gel battery is the way to go.

/per

[Carina Lass]

+1 perfrej