Battery replacement on power pack

[Alan Conroy]

I have a 250A Celestron branded power pack. It seems to be losing the ability to hold charge. How easy/safe is it to replace the batteries with those that are immune from memory effect?

[alan potts]

I changed the battery on mine after leaving it out all winter and forgetting to charge it, it basically ruined the battery. I found the hardest thing was getting all the dam screws out that hold the two plastic halves together, it was never ending. Once I had done this with care not to break any of the wires to the radio  the main battery is with just two small bolts holding the jump power cables on and charge supply. I removed the jump cables as I will never need them.

One of my fellow Mods did put a 22ampH battery back though he had to drill out the connector cables by 1mm. I found it easy to find a replacement so in the UK should be no issue.

[ronin]

I do not think it is (or can be) a straight replacement.

The internals of the battery are different but that also means the charger is different.

A "normal" one you more or less simply plug in and give it a fairly fast recharge, the deep cycle ones require a different charging process. They are more or less trickle charged at a slow rate.

As the charger in your unit will be for the "normal" variety it will charge too fast and so damage the deep cycle type.

There may be a sort of intermediate variety, normal technology, more robust to a long drainage and able to take a normal charger - but I am not aware of one specifically. I will say I am thinking of some of the gel batteries here. The descriptions tend to be a bit vague. many sort of imply something but do not openly state it.

You can replace the existing one witj another similar item, but the deep cycle variety is more of a problem.

Had better say I actually have no idea what happens with a deep cycle if you use normal charger, and the charger on a power pack may be small enough that it qualifies as a trickle charger - they are not going to put a big charger into one of them. I suppose they do not specify the charge rate ?

[Alan Conroy]

Many thanks for such prompt and helpful replies. I will go for a replacement with the same spec battery. Pity these items do not come with a meter to check available charge

[ronin]

What you want is a nice cheap cookery timer, one of the budget shops for about £1.

Wind it up to 60 minutes and when it goes off you pack up. No "Just 10 minutes more." you pack up when it goes off.

Equally what is the scope and what do you run besides the scope, if anything?

I have one of the small Tracer Lithium batteries that lasts about 3 to 4 hours and does not get "damaged".

There are Lithium ion ones rated at 12v and 6.8Ah for around £18.

They are basic but for a 12v supply for something pulling around an amp most of the time they should do.

[Alan Conroy]

It is a Celestron 9.25" SCT on a CG5 GoTo Mount but I run that from the mains so the power pack is mainly for the collector plate dew heater. I am going to need it at some point when away though.