Portable 12 Volt Power

[Stardrifter_WA]

I am looking for a replacement portable power pack for my Celestron 250A PowerTank, which I use with my Celestron 8' SCT.

I have had two Celestron 250A Power Tanks and they have both failed. In both cases, the charging circuit failed. Unfortunately, in both cases, they worked fine until they were left stored for an extended period, so were out of warranty. At first, I had thought it was the battery but they were fine and it is definitely the charging curcuit.

I called the dealer where I bought them from and he advised that they had had about 15 of them fail that they have previously replaced, so I am not going to replace with the Celestron Power Tank again, as they are just not reliable enough.

I asked if Celestron would be able to provide a replacement charger board. I was advised that it was unlikely and that I would have to contact Sheldon & Hammond as they are the Celestron distributor. Unfortunately, I know from previous experience that that would be a waste of time.

So, can anyone recommend a reliable replacement please?

Cheers Peter

[mill]

To make it easy, just take the charger board out of the powertank and fit a grey or red Anderson plug (75A) with some wire and feed it out of the powertank.
Get a cheap external charger and fit the same type anderson plug instead of the connectors coming with the charger and Bob is your uncle.
It is a bit extra work now but dirt cheap.

[rally]

Peter,

Sounds like you just need a good quality 12v charger and connect it directly to the battery internally.

Why not get yourself one of the microprocessor controlled types of sufficient wattage to allow for future expansion.
I am guessing that the battery in that unit isnt particularly large and probably with a laptop, camera system dew heaters etc would get over discharged each night anyway.

The charger will cost as much as the Celestron however - I see Amazon has those for $65 !

CTEK have a good range but I am sure there are Chinese equivalent smart chargers - get something with at least 3 stages, preferably 4 or even 5
For a large 100AH battery you would want 10A charging capacity or better.

Oops Martin beat me to it while I was helping the kids !

[MrB]

The advice from Martin would be the best idea, cheapest too if the batteries are still healthy.
However the smaller Sermos/Andersons (http://www.jaycar.com.au/productView.asp?ID=PT4405&form=CAT2&SUBCATID=990#1) plugs are perfectly fine for use with the low currents from a charger.

[Stardrifter_WA]

Thanks Rally and Martin.

I like the Power Tank and I will use your suggestion Martin to bypass the charger circuit, as this appears to be a common problem and your solution will solve the problem nicely, thank you.

Rally, the Power Tank serves the purpose nicely as I am only a visual observer and am not yet into "digital" astrophotography, however, I do appreciate your input, as you make quite a good point. Although I have previously done astrophotography, it was back in the film days.

I use to be interested in photography many years ago, but lost interest until recently. I have only just bought my first Digital SLR (Canon 60D) and am in the process of bringing myself up-to-date.

Cheers Peter