I think my Powertank as died.

[M4lcs67]

Was all geared up last night for my first sesh with my scope in a very long while. Set it up in the daylight and had it balanced nicely with all associated accessories attached, dew heatertape, dewsheild etc.

Switched it on, put all info into the hand controller and set it off to slew and nothing happened. On closer inspection the meter on the powertank then was showing zero.

Now I know how to treat powertanks and keep mine charged religiously even when I am not using it. My powertank is 2-3 years old and if it has lost all it's power then I know it will be knackered and I will have to replace it. Bit of a downer if that has happened. I was really looking forward to last night. I ended up manually slewing the scope to a few objects, but was thoroughly brassed off, so I brought it all back in.

To anyone who has a large SCT on a goto mount and who also uses a heatertape, how long an observing session should you expect to get out of a fully charged powertank? (I have a splitter so that I can run two things from one tank)

After last nights fiasco, I put the tank onto charge and have left it on charge. Later I will set up the mount in the house and give it another try just to check it one last time. I am pretty sure that it is gone though.

[Mark at Beaufort]

Malc I can understand your frustration. Over the years I have bought a number of Powertanks and they never last more than 2/3 years even when they are regularly charged. I think that a number of members, especially when you need to run the scope, dewtaps etc buy a separate battery and purchase individual leads as per the attached link - http://www.astronomiser.co.uk/pwrhbx.htm

Hope you get sorted soon.

Mark

[M4lcs67]

Hey Mark,

Thanks for the info. I bought a cigar lighter splitter (2 into1) as I thought that would be enough, but from what you are saying I would be well advised to get a powertank for the goto and another for the heatertape?

[skir]

Mmm, that is irritating. If it is dead then perhaps replace it with a leisure type battery. I've just bought a 33ah job for £41 delivered which works out as more juice for a lot less dosh than a power tank. http://www.ebay.co.u...984.m1497.l2649

[Space Dragon]

Two batteries is the way to go, another thing to lug around, I know, but i had a splitter on one battery to begin with and it always showed low charge after a few hours.

I think these batteries don't like being discharged to nearly empty, they're never the same after.

[Grotemobile]

The dew strip, really eats the juice.

I have put mine on a mains transformer.

You get through a couple of hours &

find the scope mists up because the

battery is flat.My whole set up is from

the mains now.End of problems.

Steve.

[ollypenrice]

I don't like powertanks and a friend in the car trade stopped selling them because of the high rate of returns and the number of annoyed customers he was getting. I'd always go for a deep discharge, AKA caravan/boat/leisure battery. These are designed for the long slow discharge you make in astronomy.

Olly

[starnut]

leisure battery +1

[M4lcs67]

Cheers guys.

I suppose many people choose the powertank route is for convenience, but I hadn't thought of these leisure batteries before. How easy are they to look after in comparison to the powertanks? Do you need to buy additional stuff to charge them with from a domestic wall socket? Something with crocodile clips?

I also have an outside 240v mains power socket in my garden which is about 20 feet from where I set up. Maybe getting some sort of mains transformer for the goto and dew heatertape could be an option if one exists? They would obviously have to convert to a cigar lighter type socket, but then I would have unlimited power then?

Also is it safe running mains power when there is so much dew around? My house is pretty new and has a mains breaker for all the power points in the house including the garden.....

[langman78]

Buy a jumper pack. They pack loads of charge, are normally a LOT cheaper than power tanks. And you can always jump start your car if it goes flat

[Grotemobile]

This is my mains set up & no

batterys in site.

Steve

[James]

I suppose many people choose the powertank route is for convenience, but I hadn't thought of these leisure batteries before. How easy are they to look after in comparison to the powertanks?

The bigger leisure batteries/deep cycle batteries are designed to cope with heavier draining - if you recharge after every use etc then a good capacity lesiure battery should last for many years. Powertanks are very convenient (I have a five year old one that's going strong) but they are a little like car batteries - they aren't designed to be heavily drained. The number of recharge cycles you'll get is related to the amount you discharge the battery. Even with a good recharger if you drain 80% of the Powertanks capacity each time you use it you will get a lot less recharges... if you drain only say 40% you'll get more recharge cycles. The one I have has probably never been discharged more than 30-40% at a time hence it's longevity.

With a PowerTank using a goto scope and a dew strip will be a fair whack on the battery - it'll cope fine for a few hours (assuming you're talking about the 'standard' 17AH varieties... but if you drain it below 50% a lot (easy to do with a dew strip!) then it's lifespan will be shorter.

Ken (merlin66) on here has always advised using a couple of 20AH Gel-cell batteries with a good recharger - that's good advice, his setup has lasted years and gel-cells are more forgiving of being drained more.

I use 2x 86AH deep cycle/marine/batteries with a good charger and they do me fine - even with real effort I don't drain them more than about 25-30% each session.

If you'd rather go the PowerTank route for the convenience/cost, be it Skywatcher/Maplin/etc then consider getting two and putting the goto on one and dew strip on the other and invest in a good charger By default the load on each will be less than before and they should have a longer lifespan.

James

[skir]

Buy a jumper pack. They pack loads of charge, are normally a LOT cheaper than power tanks. And you can always jump start your car if it goes flat

The problem with these is they are designed to provide a lot of charge quickly to get the car started, not for being used continually and being discharged to almost flat. That will kill them in short order. A leisure battery is a better bet for what we do.

[M4lcs67]

Hey James,

Brilliant advice, thanks. Can you overcharge these deep cycle batteries or once they have taken as much charge as they can from the wall socket do they stop taking anymore? I have never heard of these G-cel batteries before. I thought it was just lead-acid and that kind of thing.

[skir]

Cheers guys.

I suppose many people choose the powertank route is for convenience, but I hadn't thought of these leisure batteries before. How easy are they to look after in comparison to the powertanks? Do you need to buy additional stuff to charge them with from a domestic wall socket? Something with crocodile clips?

I also have an outside 240v mains power socket in my garden which is about 20 feet from where I set up. Maybe getting some sort of mains transformer for the goto and dew heatertape could be an option if one exists? They would obviously have to convert to a cigar lighter type socket, but then I would have unlimited power then?

Also is it safe running mains power when there is so much dew around? My house is pretty new and has a mains breaker for all the power points in the house including the garden.....

if you've got one of those conditioning chargers that you've been using on the power tank then it should work ok on a leisure battery. But obviously check its instructions first to make sure it is suitable. Most chargers have credible type clips so you should be ok there?

flo do a mains transformer so that is a possible, depends really on where you plan to mainly use the scope I suppose.

[skir]

Hey James,

Brilliant advice, thanks. Can you overcharge these deep cycle batteries or once they have taken as much charge as they can from the wall socket do they stop taking anymore? I have never heard of these G-cel batteries before. I thought it was just lead-acid and that kind of thing.

if you use the correct type of charger it is intelligent enough to see when the battery is full charged and not charge any further, it will then spot when more charge is required and do that. It'll keep the battery in good condition. The old style chargers did not have that ability so would just keep applying charge which would eventually kill some battery types.

[M4lcs67]

Yeah skir,

I think you are right. It is slow, steady consumption that we are after.

Grotemobile,

What kind of powersupply do you use? Luckily I have several options open to me. The leisure batteries or as I have the mains powersupply close to where I set up, I could get a transformer and run that instead. Of course price of each option over reliability, ease of set up etc isn't really an issue. Ultimately having invested alot of money in some nice kit for it to be let down by a £25 powertank is a little silly.

Basically I want power that is going to be consistent, reliable and easy to set up. So far, all of my observing has been done in my back garden, so having the mains power just a few feet away could sway things in that direction. However I may look to take the scope with me at some point and that is where having the batteries would have the edge.

[M4lcs67]

Hey Skir,

I bought my Maplin powertank a few years ago now and I would suggest that the thing isn't going to be that spectacular for £25. And the charger will be the bare minimum they could get away with.

[M4lcs67]

Hey James,

Can you recommend the deep cycle batteries and charger that you use for your set-up? Is there a link to where I can take a look?

[skir]

Hey Skir,

I bought my Maplin powertank a few years ago now and I would suggest that the thing isn't going to be that spectacular for £25. And the charger will be the bare minimum they could get away with.

I guess the charging element is part of the maplin unit then? If buying a charger for the agm type leisure battery ctek do some good chargers typically around £35 for a base model. I will get one to charge my leisure battery (linked above) and it will come in handy if needed for the car battery too.

[BargeGazer]

Leisure battery and a good charger (Ctek) is the way to go. Battery from any good battery supplier - several do free next day delivery - just Google for it. Amazon do the Ctek chargers.

[ollypenrice]

If you have mains power 20 feet from the scope then I wouldn't entertain a battery for ten seconds. Just use mains. That's what we do here. You can put a circuit breaker on the line you're using for the scope and that should stop the house from getting cut in the event of a short. But the best thing is to avoid shorts. It just needs a bit of thought to keep both ends of your cable dry. A plastic box with lid at the scope end with a notch high up to let the cables in and out will do the trick. I do have a Celestron transformer marketed (but clearly not made) for observatories. However, you can just as well use proprietory stabilized mains-to12 volt power supplies from the high street. Go for the 2.5 amp ones and they'll handle most things. I use a mixture of both. We often have six or seven setups running from the mains here and while it's drier than the UK the morngings can be very damp. Each setup might have three or four separate power suppliers. You only need to keep the business ends dry and that really isn't difficult. I had an outside power supply when I observed in the UK, too.

Olly

PS I now have a set of external sockets which are independent of the house on their own circuit breaker but this is really to stop a short in the house from bringing doom and despondency to the imagers!

[M4lcs67]

Thanks for the advice, Olly. More good info.

I do have built-in mains breakers on my outside sockets, so there will be no problem there. The sockets also have little covers on them, so that should keep the dew at bay. With regards to 12v power supplies I have seen this from Maplin

http://www.maplin.co.uk/13.8v-regulated-mains-power-units-231.

Although it runs at 7amp. Not the 2.5 that you suggested. Would that be ok? Also I would need to get some adaptors for my cigar lighter sockets so that I could attach the cables to the power supply via the ring tongues.

[P_Monty]

The current is fine - that rating is just the maximum it can supply. Your setup will just take as much as it needs...

[M4lcs67]

Here are some pics of my rig set-up with some new acquisitions added. Baader Hyperion 17mm ep, Skysurfer V red dot finder, ADM saddle and Astrozap heatertape. Always a good idea to set up in daylight, but when you find out your powertank is knackered after you have gone to all the trouble of setting up. Doesn't do much for your mood. Well that 'aint going to happen again. Just ordered a 12v mains power supply which should be here soon. At least i'll have unlimited power then.