Bypass car lighter section on Skywatcher power lead?

[Chris Owen 66]

Hi all,

I use the normal supplied cable to power my Skywatcher 10" Dob.  Battery cables on one end.....power connector on the other. It's worked fine for years. But lately the car lighter section halfway along the cable has become very unstable. Often I have to twist one part inside the other backwards and forwards to get the LED light to illuminate. If I push it in hard, it comes on, but as soon as I let go, it goes out again. Sometimes it flickers, sometimes it's stable....but often it'll go out of it's own accord as I'm using the scope, which is obviously frustrating as it means I have to re-align, etc, as I use Synscan app to control the scope and track objects. So does anyone know if it's possible to just cut-out the lighter section, and just re-attached the loose ends (using small connectors of some kind)? I'll never use the car lighter function, so it's of no great loss! If it's a simple cut-and-paste job, at least I'll have a stable power supply again. Of course I can tell which lead is positive/negative at one end due to coloured clamps, but what about the other end? Will it damage the scope if I accidentally connect negative to positive, or will it simple not work until I connect P to P and N to N? Many thanks! 

[wulfrun]

You could snip the connector out, solder the wires together and put heat-shrink sleeving over the joins. If it were me, for safety I'd stagger the joins, double sleeve them and also wire an in-line fuse close to the positive croc clip. Again, for me I'd like polarity protection (just a heavy-duty diode will do) because yes, the polarity matters and reversing it, even momentarily, is quite likely to destroy any electronics connected. Because it's possible to connect the leads the wrong way around, it'll happen at some point!

Edit: actually, why not connect the croc clips to the (snipped) long lead? Simpler, if it leaves enough lead left.

Edited June 6, 2022 by wulfrun
added info

[teoria_del_big_bang]

You can remove the cigarette type connector, they are pretty poor anyway I hate the things for poor connection issues
BUT please put an in line fuse in its place. If there are any short circuits car batteries, or many other types of battery for that, are capable of delivering many amps for short periods.
Also make sure the polarity is correct.
Personally for the sake of £20 or so considering the cost of your equipment I would just buy a new cable altogether.

Steve

Edited June 6, 2022 by teoria_del_big_bang

[Chris Owen 66]

Many thanks for your reply and suggestion.....yes I could indeed just attach the croc clips to the leads on the other side of the car lighter. Why didn't I think of that? how can I tell which is P and which is N though? I know very little about electrics, sorry. Would I need a meter to tell?

[Chris Owen 66]

Just now, teoria_del_big_bang said:

You can remove the cigarette type connector, they are pretty poor anyway I hate the things for poor connection issues BUT lease put an in line fuse in its place. If there are any short circuits car batteries, or many other types of battery for that, are capable of delivering many amps for short periods.
Also make sure the polarity is correct.
Personally for the sake of £20 or so considering the cost of your equipment I would just buy a new cable altogether.

Steve

Thanks Steve. Where might I get a new cable...I've looked and looked online but can't seem to find one. Thank you.

[teoria_del_big_bang]

Just now, Chris Owen 66 said:

Thanks Steve. Where might I get a new cable...I've looked and looked online but can't seem to find one. Thank you.

Ah, now not sure, I can have a look but can't promise 🙂 

Do you have a better picture of the end that plugs into your Dob ?

Steve

[wulfrun]

7 minutes ago, Chris Owen 66 said:

Many thanks for your reply and suggestion.....yes I could indeed just attach the croc clips to the leads on the other side of the car lighter. Why didn't I think of that? how can I tell which is P and which is N though? I know very little about electrics, sorry. Would I need a meter to tell?

Yes, you'll need a test-meter, ideally. Don't guess, if you are not absolutely, totally, 100% sure it could well ruin the mount. And don't even think about it without a fuse and polarity protection. You may get away with it for years but it's a "when" not an "if".

If you're not confident with electronics and don't have the gear, you're risking much so  better to entrust it to someone else or find something ready-made.

[Chris Owen 66]

Hope this photo is of some use Steve. The outer diameter of the plug looks to be 5mm. This fits directly into the box on the side of the Dob's mount. Thank you for your help!

Edited June 6, 2022 by Chris Owen 66

[DaveL59]

The car ciggy plug is usually tip +ve and the side spring part -ve. Worth double-checking tho with a meter if you have one. As with other's suggestions, do put an in-line fuse on the +ve and if you can a protection diode as its easy in the dark to hook the croc clips the wrong way round.

[teoria_del_big_bang]

Yes I thought it woud be, I would be pretty sure if its for a SW Dob that it is a 5.5mm x 2.1mm connector.
Loads of cables available with this end, the problem will be if you want to get rif of the cigarette lighter plug.
THIS would be a direct replacement for your cable (dont get the ring end ones unless you want to attache a fuse yourself), so available in 2M or 5M and they are great cables.
 

But if the issue, or part of the issue is corrosion of the socket on the short bit of cable you have and not all to do with the long cable then you could still have connection issues,

Steve

[Chris Owen 66]

Thanks gents. Taking into account the polarity, the in line fuse and potential damage to my beloved Dob, I think a quick call to a local spark would be in order! He'll probably only charge half an hour anyway.

 

[Chris Owen 66]

3 minutes ago, teoria_del_big_bang said:

Yes I thought it woud be, I would be pretty sure if its for a SW Dob that it is a 5.5mm x 2.1mm connector.
Loads of cables available with this end, the problem will be if you want to get rif of the cigarette lighter plug.
THIS would be a direct replacement for your cable (dont get the ring end ones unless you want to attache a fuse yourself), so available in 2M or 5M and they are great cables.
 

But if the issue, or part of the issue is corrosion of the socket on the short bit of cable you have and not all to do with the long cable then you could still have connection issues,

Steve

Thank you for the link Steve. How does that cable connect to my battery though?

[teoria_del_big_bang]

3 minutes ago, Chris Owen 66 said:

Thank you for the link Steve. How does that cable connect to my battery though?

Thats what I meant when I said you would still have to use your existing short bit of cable with the cigarette socket and if it was that socket that was going dodgy not the plug side then you would still have an issue so still looking for an alternative solution.

Steve

[teoria_del_big_bang]

Found one HERE that would work but out of stock

What are you connecting the croc clips to, would some other type of connector fit ?

Steve

Edited June 6, 2022 by teoria_del_big_bang

[DaveL59]

it's a pity they don't sell the type of flying socket that is latch/lockable tho you can get bulkhead types for boats/motorcycles. I fitted one in the car that I run a multi-outlet 12v/USB adapter from to drive the various devices I have. Basically you insert the cig plug and turn and it stays put, maintaining a good contact.

The one I fitted was something like this but a single-outlet version

Qiilu Cigarette Socket, 12V-24V Dual Port Surface Mount Cigarette Lighter Socket for Motorbike Car Boat : Amazon.co.uk: Automotive

 

[Chris Owen 66]

15 hours ago, teoria_del_big_bang said:

Found one HERE that would work but out of stock

What are you connecting the croc clips to, would some other type of connector fit ?

Steve

The croc clips directly to the metal terminals on the battery. Thank you for the ebay link, that looks ideal.....I'll contact the seller to see when those are back in stock, and certainly cheaper than using an electrician.

[DaveL59]

What battery are you using?

Some allow you to bolt the cables to the battery terminals which means you could leave the ciggy socket permanently attached rather than relying on croc clips. Might also make other solutions feasible, such as wiring a fused short cable with 5.5/2.1 plug direct to the battery and then only needing a 5.5/2.1 plug/socket extension lead to run to the scope.

[Chris Owen 66]

4 hours ago, DaveL59 said:

What battery are you using?

Some allow you to bolt the cables to the battery terminals which means you could leave the ciggy socket permanently attached rather than relying on croc clips. Might also make other solutions feasible, such as wiring a fused short cable with 5.5/2.1 plug direct to the battery and then only needing a 5.5/2.1 plug/socket extension lead to run to the scope.

It's an Ultramax 12V, 7Mah, with flat terminals like this -  I'd prefer to get rid of the unreliable cigarette section, as it's so unstable. I feel there's 2 good options suggested by you good people......cut away and dispose of the cigarette lighter section and directly attach the croc clips to the wires that have the connector at the other end (so I'd have a cable with croc clips at one end and the connector at the other, but also with an inline fuse)  or find a cable online that fits the same bill! 

[DaveL59]

Ah ok, so with that battery you'd need a cable with push/lucar connectors to attach to the battery, IIRC they are the same size/type as the crimp-on connectors used in cars. Of course these can also be yanked off if the cable gets tugged but kinda better than a croc connector that may accidentally short across the terminals.

Not finding anything suitable on the long river place but not hard to make up something like that if you have the crimp plugs and tool, ensure you use insulated push connectors tho to prevent accudental shorting if something gets dropped across the terminals, makes a nice loud pop etc does that 😉 Inserting a fuse isn't hard either using something like this (swapping the blade fuse for a 5A one of course). 

STANDARD INLINE CAR FUSE BLADE HOLDER 30AMP 12V RED & BLACK SPLASH PROOF K265 ROBINSON : Amazon.co.uk: Automotive

A local sparky would be able to do that easily if you can't find one to buy or make one up yourself. You could either go the whole length from battery to mount or have a short lead for the battery made and then just get a simple extension lead to go between that and the mount:

Liwinting 3m/9.8ft DC Extension Cable 2.1mm / 5.5mm Male to Female Connector, DC Power Cord Extension Cable for Power Adapter, 12V CCTV Wireless IP Camera, Monitors, Led, Car - Black: Amazon.co.uk: Electronics & Photo

You'd need to order carefully to be sure it can carry the current and if the plug end is right angled etc per you requirement, or of course get one made/modified to suit - i.e., removing the ciggy plug on your cable and replace that with fuse & insulated lucar plugs.

[DaveL59]

In fact, if you have some crimp terminals then this might be an easy option

zdyCGTime 14AWG DC 5.5mmx2.1mm Male to Female Quick Disconnect Wire Harness Extension Cable,with 5A Blade Fuse Holder,for Portable Powers,LED Strip,Surveillance Camera,Security Equipment,40cm.: Amazon.co.uk: Electronics & Photo

Cut off the socket and crimp the lucar terminals in its place then you just need the M-F 5.5/2.1mm extension cable and you're there. Do check the fuse rating and swap to a 3A or 5A tho and carry some spares just in case.

[wulfrun]

25 minutes ago, DaveL59 said:

In fact, if you have some crimp terminals then this might be an easy option

zdyCGTime 14AWG DC 5.5mmx2.1mm Male to Female Quick Disconnect Wire Harness Extension Cable,with 5A Blade Fuse Holder,for Portable Powers,LED Strip,Surveillance Camera,Security Equipment,40cm.: Amazon.co.uk: Electronics & Photo

Cut off the socket and crimp the lucar terminals in its place then you just need the M-F 5.5/2.1mm extension cable and you're there. Do check the fuse rating and swap to a 3A or 5A tho and carry some spares just in case.

Also has 2 other advantages that way. (1) the extension lead means there's a pull-apart connector that should pop if the cable is tugged. (2) the lucars can be left in place permanently on the battery, removing the risk of accidentally swapping polarity.

[900SL]

First thing I did with my new Vixen mount is snip off all the clips, cigarette type sockets etc from all my 12v stuff. I then crimped Anderson Powerpole 12v plugs to everything and run it from this fused panel. 12v DC input on line 1 from a 40Ah battery

[Chris Owen 66]

16 hours ago, wulfrun said:

Also has 2 other advantages that way. (1) the extension lead means there's a pull-apart connector that should pop if the cable is tugged. (2) the lucars can be left in place permanently on the battery, removing the risk of accidentally swapping polarity.

Thank you for the link, much appreciated. Interesting. Just so I'm following this suggestion.....I cut my cable at position A (and dispose of the cigarette lighter and crocs), then add crimp terminals at the 'new' end of the cable to enable me to attach it to the battery. Then the extension lead in your link just connects to the other end (position B), thus providing an inline fuse. Sounds great! My only question would be, once I've cut at position A....how can I tell which part of the cable is P and which is N? IF I just guess, and accidentally attach the cable's P to the battery's N terminal....will it a) just not work, or b) possible cause damage to the scope's motor electrics? Thank your for your help on this.

 

[wulfrun]

39 minutes ago, Chris Owen 66 said:

Thank you for the link, much appreciated. Interesting. Just so I'm following this suggestion.....I cut my cable at position A (and dispose of the cigarette lighter and crocs), then add crimp terminals at the 'new' end of the cable to enable me to attach it to the battery. Then the extension lead in your link just connects to the other end (position B), thus providing an inline fuse. Sounds great! My only question would be, once I've cut at position A....how can I tell which part of the cable is P and which is N? IF I just guess, and accidentally attach the cable's P to the battery's N terminal....will it a) just not work, or b) possible cause damage to the scope's motor electrics? Thank your for your help on this.

You won't, easily anyway. Ideally you'll need a test-meter, so beg/borrow/buy one. It doesn’t need to be an expensive one (the likes of Aldi & Lidl often sell budget models), it just needs an ohms or continuity function which most have. Failing that, cut and strip the wires and determine which cut end makes continuity in a simple battery/bulb circuit. You'll have to use the outer of the plug since the inner isn't easily accessible but it's obviously the other wire once you know which is the outer!

Don't guess! Reverse-connecting P to N (as you described) is pretty much guaranteed to fry your mount's electronics. Check, double-check and triple-check. Again, a test-meter will easily confirm you have it right in your final lead, end-to-end.

EDIT: I think @DaveL59's suggestion above involved cutting the socket off the lead he linked to, not the one you already have.

EDIT2: I see what you have in mind, modify your existing lead and plug the fused lead in to the far end? It'll work BUT the fuse will not protect your lead, it needs to be physically close to the battery to do that. Any fraying or damage to your modified lead means the battery will happily set fire to it 😞

Edited June 8, 2022 by wulfrun
added info

[DaveL59]

As @wulfrun has said, I'd suggest that fused lead I linked earlier be modified to connect direct to the battery, which will give you a short fused spur. You'd then buy an M-F extension with the 5.5/2.1mm plug/socket to run to your mount.

You can of course modify your existing lead which would lose the option of using a Ciggy socket later should you ever need to, but I'd recommend you fit a fuse at the battery end if you do this. The fuse would protect the device and also the cable from overload/short circuits. Also you do need to be absolutely certain you have the +/- wires identified so you fit this correctly to the battery. If you get this wrong, bye-bye mount electronics, much the same as if you connect the croc clips the wrong way round. If you did this mod then you'd not need an extension as you would just use the modified wire to hook to your mount directly. In many ways, less connections/plugs between source and device is generally a good thing as it avoids losses at the connection, but for 12v xA power it isn't gonna make much difference.