battery packs

[planet searcher]

hi, i need to get a new battery pack for the sky prodigy 130, as the wire which you plug in to the scope got trapped in the scope its self. and has split  the black wire exposing the inside cable. does any one have a link as to where i can buy a new one. many thanks 

[alanjgreen]

Celestron cable

https://www.firstlightoptics.com/astronomy-cables-leads-accessories/celestron-car-battery-adaptor-for-all-nexstars.html

better quality cable

https://www.firstlightoptics.com/power-accessories/lynx-astro-mount-power-cable-for-celestron-mounts.html

 

[Daz69]

If it's only exposed the copper wire inside the black sheath, just wrap "proper" electricians tape around it, not sellotape or parcel tape. If it's exposed the copper wires inside of several wires, disconnect it from the power source, separate each set of copper wires, and tape up individually. Can you post a photo?

If all you have done is torn the sheath, a £1 roll of electricians tape might be cheaper than buying a whole new lead. Once done, you need to establish a way of not allowing it to happen again. 

Better still would be to cut the wire, re-solder and cover with heath shrink tube. It's always worth learning how to solder. A whole set up of a cheap 30 watt soldering iron, flux, solder and a selection pack of heat shrink tube would be circa £20.

[Geoff Lister]

As well as following the above advice from Daz69, consider hanging the battery pack from the rotating part of the mount. I have had a Skywatcher Skymax 127 for a few years and, earlier this month bought a Skyprodigy 70. These two probably come from the same factory in China, so have similar mechanics and external plastic covers. On both, I have glued a plastic coat-hook high up on the sloping front face of the mount, and the battery pack satchel hangs from the hook, and rests on the mount, without catching on anything as the mount slews. The Skymax pack uses AA cells, so is smaller than that of the Skyprodigy (D cells). Before gluing the hook, it's important to check that the bottom of the pack misses the tops of the tripod legs, but the pack handle can be shortened by wrapping round the hook.

I also use a plug-style 12V 2A mains adaptor with a long 12V lead, and have glued a small clip adjacent to, and slightly above, the mount's power inlet socket. This keeps the lead clear of the tripod and makes it more difficult to accidently pull out the lead during slewing, or if you catch your foot in it in the dark.

Geoff

[jambouk]

Get an old car battery rather than spend money on a "dedicated" astronomy battery. If you are just powering the mount and dew bands and not running laptops for hours and hours, an old car battery will be perfect. Go to your garage and ask if they've got any old car batteries they are waiting for the scrap man to pick up. If you have a multimeter take it with you, else they'll have one. Stick it on the old batteries and pick the one which suits you in terms of physical size and weight, AND which has the highest resting voltage. Most of these batteries won't have been attached to a car for a couple of months so the resting voltage will have fallen; if the resting voltage is over 12.2v or so it's a good battery. Even the really filthy ones scrub up well and often end up looking brand new so don't be put off by oil and grease. Garages are often given a £5 per battery by the scrap man so give them a fiver or buy then bacon butties. Get a trickle charger like this one (http://www.argos.co.uk/product/7405392) and then either something like this (https://www.amazon.co.uk/Accessory-Socket-Battery-Clamps-Crocodile/dp/B01KPNBSY8/ref=sr_1_1?ie=UTF8&qid=1487499125&sr=8-1&keywords=12v+battery+terminal+clips) or if you want a more reliable connection, get this (https://www.amazon.co.uk/d/DIY-Tools/Am-tech-J0250-Heavy-Duty-Battery-Clamps-2-Piece/B003H6HPWK/ref=sr_1_1?ie=UTF8&qid=1487499142&sr=8-1&keywords=12v+battery+terminals) and this (https://www.amazon.co.uk/VORCOOL-Waterproof-Motorcycle-Cigarette-Lighter/dp/B00VJS6PBA/ref=sr_1_4?ie=UTF8&qid=1487499154&sr=8-4&keywords=12v+socket). 

You'll end up with a nice reliable and stable power source which will likely have 40-70 amp hours of juice depending on the size of battery you get in the first place. Clean it up, leave it on trickle charge for a week, add your connections (make sure you get the polarity correct else you'll blow up the mount), and job's a good un. You can put it in a battery box if you want (https://www.amazon.co.uk/Caravan-Plastic-Leisure-Battery-divider/dp/B004N6UQLK/ref=sr_1_4?ie=UTF8&qid=1487499596&sr=8-4&keywords=12v+battery+box) and put terminals on the outside if you like DIY stuff.

People go on about "car batteries are not good for astro because they are not deep cycle batteries" but if you are drawing 10 amps in a night and it's a 70 amp hour battery then you are only drawing a seventh of the juice and you'll charge it up at the end of the night anyway. I suspect you won't even draw anywhere near 10amps. 

If you are running lots of energy hungry kit then you need to consider a big capacity, deep cycle battery, but for running your mount, an old car battery will do the trick nicely for many years and cost you under £30.

James

 

[Grotemobile]

I had to get a new battery for the car. Kept the old one, & got my self a charger. Glued a couple of 12v lighter

sockets on top & bought a battery carry handle. It is a small  battery off my 1.0 Toyota . 35amp hrs. Use it

with a compressor , to pump up my bike & car tyres . Good portable power supply for the scope as well.  

[Skipper Billy]

I know car batteries and leisure batteries look similar but that's where any similarity ends.

A car battery is designed to put huge power out very briefly then be immediately recharged.

A leisure battery is designed to put low power out for a long time and not necessarily be charged again immediately.

Whilst a car battery will do the job for a while you will get MUCH better performance out of a leisure battery.

Right tool for the job etc etc ......

[Geoff Lister]

An old car battery would probably do the job, but will eventually "sulphate up" on repeated deep discharge. True deep discharge lead-acid batteries have different plate design to avoid this. However it will not solve the problem of cord-wrap as the mount turns.

NiMH rechargeable AA cells will give you about 2500 mAh (higher with "D" cells, but have a terminal voltage dropping to about 1.1V. The holders supplied with the Skymax & Skyprodigy mounts are designed for 8-off alkaline cells, so if you replace these with NiMH, the pack voltage drops too low before the cells are discharged. I got round the problem by buying a couple of 10-cell holders on eBay (other retail sources are available), and adding a short lead with a 2.1mm ID power jack on the end. This still slipped into the satchel, but the flap stayed open. This still works with alkaline cells, provided that you fit 8 good cells + 2 dead cells wrapped in aluminium foil.

One of my "daytime" hobbies is sailing radio-controlled model yachts. The receiver/servo systems tend to have similar power requirements to a modest telescope mount, but running at 6V instead of 12. I have found that a shrink-wrap battery pack, (around £7 on eBay) containing 5 AA 2500 mAh cells with flying lead (and connector to mate with the receiver), will give me a decent day's sailing. I made a "Y" lead by butchering 2 servo extension cables, to link 2 battery packs in series, and adding a power jack at the base of the "Y". Once again, this assembly slips inside the Skymax's satchel (even more space in the Skyprodigy's).

I had made some current measurements on the Skymax mount, with its 127mm MCT optical tube, and found that it took about 90 mA at start-up (no motor movement), 220 mA whilst tracking (rate 1), and about 350 mA with both axes slewing at max rate 9. A few days ago, I made similar measurements on the Skyprodigy, with the lighter 70mm refractor optical tube. The current at start-up was now 350mA (the Star Sense camera and interface seems to consume about 260 mA extra), 400 mA whilst tracking and 550 mA max rate slewing. I would expect a slightly higher consumption with the 130's reflector.

I have not done any endurance tests, but I would expect upwards of 4 hours "Align and view" Skyprodigy operation from a battery of 10-off 2500 mAh cells.

Geoff

 

[jambouk]

19 hours ago, Skipper Billy said:

I know car batteries and leisure batteries look similar but that's where any similarity ends.

A car battery is designed to put huge power out very briefly then be immediately recharged.

A leisure battery is designed to put low power out for a long time and not necessarily be charged again immediately.

Whilst a car battery will do the job for a while you will get MUCH better performance out of a leisure battery.

Right tool for the job etc etc ......

 

It's all relative. If you are running lots of equipment and deeply discharging a battery and doing this often then you need a deep cycle high capacity battery. If you are running just a mount for a few hours a week and can charge it up afterwards a reasonable capacity old car battery will be perfect and for a fraction of the cost. Yes, if you have plenty of money then go for a brand new deep cycle battery in the first instance. I'm just trying to offer a cheap alternative which for the low energy consuming user will last many years if looked after properly.

We've been running a 24" scope at our astronomical society observatory for ten years on the same four car batteries which get deeply discharged and only now are two shot, and with a bit of TLC I've revived the other two. The two revived ones will be used to now run the LED lighting and we've got some deep cycle batteries to run the scope. I've also got hold of two additional old car batteries (just last week) which I'm going to leave up there in case the deep cycle batteries are off site being charged.

James

 

[kilix]

19 hours ago, Skipper Billy said:

I know car batteries and leisure batteries look similar but that's where any similarity ends.

A car battery is designed to put huge power out very briefly then be immediately recharged.

A leisure battery is designed to put low power out for a long time and not necessarily be charged again immediately.

Whilst a car battery will do the job for a while you will get MUCH better performance out of a leisure battery.

Right tool for the job etc etc ......

yeah but you can get a car battery for a few quid as @jambouk stated above. Why spend 70$ on a celestron 7Ah battery pack, if it is nothing more than a deep cycle lead-acid battery? Buy 7Ah battery intended for UPSes for 20$ and off you go.
What annoys me, is the fact, that once you stamp "for astronomy use" sticker on a battery, you can suddenly charge people for 400% of it's price and they will still gladly pay.

(I use a 10€ 3.2Ah UPS battery with SkyMax mount with no issues)

[jambouk]

2 minutes ago, kilix said:

yeah but you can get a car battery for a few quid as @jambouk stated above. Why spend 70$ on a celestron 7Ah battery pack, if it is nothing more than a deep cycle lead-acid battery? Buy 7Ah battery intended for UPSes for 20$ and off you go.
What annoys me, is the fact, that once you stamp "for astronomy use" sticker on a battery, you can suddenly charge people for 400% of it's price and they will still gladly pay.

 

If you are going to use an old car battery, I'd go for one that is at least 40 amp hours so you don't actually deeply discharge it. If you get a small capacity battery which isn't keen on deep discharge then you'll shorten the life considerably.