Can someone clarify info about Powertanks for me

[marineBLU28]

Hi

I have a couple of questions with regards to the Powertanks/batteries we use for our telescopes, I'm not very knowledgeable about these so please forgive me.

I have two the skywatcher tank and a halfords one I bought a few months ago as a backup but from reading all the posts about them Im a bit confused :-)

The Halfords one I did the full charge on when I got it and it has just been siting in the kitchen cupboard I haven't used it yet the skywatcher however has been outside in my SkyShed for the last few months my questions are.

Have I ruined the Skywatcher one I like many others didn't realise you are supposed to charge them every time after you've used it for a session I thought if the green light said fully charged then it was fine, also how long do you charge them for after a viewing session?

With regards to the Halfords one in the Kitchen cupboard will that be ok as I,ve never used it or do I need to charge that one as well before use and if so how long for.

Should I invest in one of the more expensive chargers to charge these batteries as opposed to the charger plug they supply with them if so which one would you recommend sorry for all the questions but I'm a bit confused about it all! and with a few days of potential stargazing coming up courtesy of the 'indian Summer' weather forecast i don't want to screw up

Cheers

[Merlin66]

I'm sorry to say, IMHO powerpacks are over-rated. They may look sexy-with the lamps and bells and whistles but they just don't last!!

I've been using 20Ah gel cell batteries for the last five years (they last forever!!) with a good triple stage electronic charger - this makes sure they are well looked after - you can't overcharge them and cook them.

Seriously, the investment in good batteries and a charger is well worth it. You can live without the bells and whistles.....

[Nathan_Pembs]

I've been using 20Ah gel cell batteries for the last five years (they last forever!!) with a good triple stage electronic charger - this makes sure they are well looked after - you can't overcharge them and cook them.

How do you go about powering a Synscan mount with a gel battery? The only lead I have for mine has a cigarette plug on the end

[Merlin66]

Easy...

You can buy or make a 12V cigar socket extension (look in B&Q or Halfords) and just either add a clamp ring or wrap on the terminal screws...

Astronomiser can supply ready made battery connection cables...

Astronomiser - Automated Astronomy and AstroImaging Solutions

HTH

[johninderby]

You can get the cigarette socket from somewhere like Maplins and attach this to the battery. Just get some connectors at the same time for the two wires on the socket that will plug onto the battery terminals. Simple job to make up and then you can use anything with a cigarette plug on the end.

I never use a powertank as the charging part of them is useless. Get a gel cell battery (or two) and a good charger. I've found a properly charged battery also lasts longer than a powertank as the battery will have been charged properly.

John

[Stu]

I would echo most of that. I use a leisure battery, 110Ah which I picked up online for a decent price. I also bought quite an expensive charger but it does allow it to be left charging all the time to maintain the battery in good condition, just trickle charging.

I did actually use this to recover one of my power packs by charging into the cigarette socket. Took a while but eventually it showed fully charged again.

Lastly, replacement batteries for the halfords packs aren't too expensive, I replaced a pp200 internal for about £14

Cheers

Stu

Sent from my GT-I9000 using Tapatalk

[Odd Thomas]

I use the cheapest motorcycle battery I could find (£6) and charge it when it needs it, never let me down and none of the fuss associated with powertanks.

[Merlin66]

Back to the original question.....recharging the powerpack...

I'd definately charge them all. probably at least 24hr for each...and hope they return to a reasonable charge and voltage.

[johninderby]

The key is a good charger. The one I use is temperature and current compensated and adjusts the charging rate as the battery is charged and then switches to a trickle charge. Makes sure the battery is charged to it's maximum capacity without being overcharged. Cost me about £100.00 15 years ago, but it was a good investment.

A fully charged gel cell can be stored away for a year without any need for topping up just so long as it is stored someplace warm. However they can be ruined in just a few weeks if they are put away fully discharged after use, so do charge them after every use. They don't have any "memory" so there is no benefit in first discharging them before putting them on charge. So top them up after every use and put them somewhere warm and they will last for many years.

They worst thing you can do is to let one go flat and then leave it in a cold unheated shed or garage.

John

[fizzer]

I too had a skywatcher powertank die on me, wouldn't charge from the supplied charger, i could leave on charge for 24 hours and not even the small lamp would light when swithced on, i went and brought a optimate 4 charger (~£50) this revived the battery and all is as good as new now. So i would have to agree that the charger is as important as the battery.

Rich.

[marineBLU28]

Hi

Thanks for all the replies obviously I went the power tank route for myself as I have no experience of batteries and what would be required to make them suitable for use with the telescope and thus potentially damaging my EQ6 as a result of my inexperience.

I'm assuming that you folks also use a certain kind of charger to charge your batteries as opposed to the ones that come with the power tanks etc? I would appreciate a link to what you would recommend for the Halfords/skywatcher ones I have.

So if I understand you correctly as well I should charge them both for 24hours before using? Just to say again that the Halfords one was charged for the time stated on the instructions but I have never used it so does it still need charging for 24 hours I'm just a bit nervous as on the instructions for these things I believe it says to watch you don't overcharge them or there is a potential fire risk so I'm bait nervous about just plugging it in in my kitchen overnight and overcharging :-)

Cheers

Carolyn

[Merlin66]

The powerpacks, for better or worse, have their own chargers "built in" so powering them from a "real" charger won't do anything...

If you don't feel comfortable re-charging them...that's OK - use them first then re-charge - see how you go.

[Stu]

Hi Merlin66. You can actually charge them via the cigarette socket which by passes the internal charging. I would only do this with a decent charger to avoid overheating etc but have managed to recover one than wasn't charging properly by doing this, then reverting to normal charging afterwards

Stu

Sent from my GT-I9000 using Tapatalk

[michael.h.f.wilkinson]

One reason I went for a powertank was that it had a 9V outlet too. I need this for my GP mount. This draw so little power I rarely need to recharge. Once I start running the laptop of it when necessary that will change. Good tip about bypassing the built in charger, Stu, thanks for that.

[Merlin66]

I use a DC-DC convertor (Maplin) with my 12V battery to power the USB hub at 6V. These convertors can be set to any voltage - so come in very handy.

[michael.h.f.wilkinson]

I use a DC-DC convertor (Maplin) with my 12V battery to power the USB hub at 6V. These convertors can be set to any voltage - so come in very handy.

True, and I could build a continuously variable DC source using an LM317 chip. I played with the idea of building my own, but the result was less compact, and not much cheaper. If you have a permanent set up you can put things together in any way you want to. I wanted a compact, all in one set up useful for travel. When taking it with me on holidays it also meant I could ditch the jump start cables and raise fewer eyebrows with the missus.

[Merlin66]

Know what you mean.

I have a "semi-permanent" set up and just gaffa tape all the "loose" bits together to form a "pack".....

[todd8137]

hi there i have the skywatcher power tank and mine is mega ,i can use it for about 3 hours a night for about 8/9 days ,soon as the charge light comes on ,charge about 8/10 hours jobs a good un never had no probs with mine and whilst use in it i always use the built in radio

cheers

[AndyG63]

Component Shop (a UK company) do very good prices on sealed lead-acids & chargers, and their delivery service is quick, too.

Not connected with this company - just a satisfied user!

The basic rule of thumb(s) are:

* Store the battery in a charged state.

* Do not short the battery (do not connect the terminals together without a load).

* Top it up when required.

* Don't let the battery freeze or over-heat.

* Battery capacity is measured in Ah = amp-hours. A 7Ah battery, for example, can nominally provide 1amp for 7 hours, or 2 amps for 3.5 hours.

* Charge using a current (usually measured in mA = milliamps = thousandths of an amp) which is no more than 1/4 of the Ah capacity of the battery. (Our 7Ah example shouldn't use a charger capable of more than 1500mA output. Lower is best.)

* To calculate charge time, divide the Ah of the battery by the A of the charger. (Our 7Ah example will fully charge in about 14 hours using a 500mA charger.)

* You can overcharge a sealed lead acid battery, but they're fairly resilient and moderately forgiving. Put a timer on the charger - better still, unplug it once it's full.

* If you're really not sure of the state of the battery, buy a cheap digital meter. Fully charged is usually around 13.2V across the terminals. Fully discharged is around 10.5-11.8V.

Andy

[Stu]

I got a 110ah leisure battery online for about £85. Very heavy but copes very well with running dew heaters plus the mount for a long time. Mount slewing is definitely better with it.

Sits on trickle charge in a cupboard, ready to go which avoids cycling through discharging

Stu

Sent from my GT-I9000 using Tapatalk

[West End Wendy]

Component Shop (a UK company) do very good prices on sealed lead-acids & chargers, and their delivery service is quick, too.

Not connected with this company - just a satisfied user!

The basic rule of thumb(s) are:

* Store the battery in a charged state.

* Do not short the battery (do not connect the terminals together without a load).

* Top it up when required.

* Don't let the battery freeze or over-heat.

* Battery capacity is measured in Ah = amp-hours. A 7Ah battery, for example, can nominally provide 1amp for 7 hours, or 2 amps for 3.5 hours.

* Charge using a current (usually measured in mA = milliamps = thousandths of an amp) which is no more than 1/4 of the Ah capacity of the battery. (Our 7Ah example shouldn't use a charger capable of more than 1500mA output. Lower is best.)

* To calculate charge time, divide the Ah of the battery by the A of the charger. (Our 7Ah example will fully charge in about 14 hours using a 500mA charger.)

* You can overcharge a sealed lead acid battery, but they're fairly resilient and moderately forgiving. Put a timer on the charger - better still, unplug it once it's full.

* If you're really not sure of the state of the battery, buy a cheap digital meter. Fully charged is usually around 13.2V across the terminals. Fully discharged is around 10.5-11.8V.

Andy

Thanks. Been looking for specific info like that for ages.

Tim

[Skylook123]

You can charge the power tanks or jump starter kits with a quality multi-mode/multi-state charger by using the jumper cables. Just connect the charger output to the cables. If the cables are always "hot", as with power tanks, leave the charging switch to off on the tank and just let the charger fill the battery. If there is an enabling switch for the jumper cables, turn it on so it will take the charge.

Think of the battery as a reservoir you are trying to fill, and the pipe is the jumper cables. As long as the voltage of the charger is higher than the voltage of the battery, the juice flows in. Most chargers start around 15V, and multimode units vary the current with need, becoming a trickle charger as the battery becomes topped off.

There is another good thread on the topic with the title about why is the red light blinking on the mount. Good information in there, as well.

[brantuk]

I have a powertank and a maplins "5 in 1" - both 17ah. Both still running well using the supplied chargers after 2-3yrs. I allways recharge for 8-12 hrs after 4-6hrs use in the field, and the same every 10wks when not in use (eg this past "summer"). They've never let me down so far though I would say I only get out once a week on average.