Cigarette Lighter connections

Folks - I'm a complete dunce when it comes to anything electrical. SO I'm hoping those experts here can help me out.

Thanks to John Murphy, I'm now the proud owner of three 17amp/hr SLA batteries and a charger.

What I would like to do is connect the three batteries up and use them to power the AP mount and a soon to be purchased dew heater (Kendrick premium).

The AP mount has a cigarette lighter power connector. I have a dual female cigarette lighter module which will accept two male cigarette lighter connectors.

I was wondering how I connect these items up without getting the polarities the wrong way round and probably causing damage. If anyone has any guidance I'd appreciate it.

Also, and perhap John can answer this, would
1. it be OK to keep the charger connected at all times (trickle charging)
2. the charger only need to be kept attached to one battery and would that charge all three - if they were interconnected.

Thanks in advance

Dave

Dave,

Connecting all three batteries together wont be a problem. You need to connect them in parallel. That is connect all three positive terminals together then connect all three negatives together. DO NOT connect them serially (serially would be like (+ -)(- +)(+ -), you'll end up with over 36v on the output if you connect them like that). Cigar plugs are almost always centre positive which means you can connect the tip to the positve leads. Connected like this the batteries behave like one big battery. It should say on the mount what polarity is expected. A symbol like;

(-)----C----(+) (with the + sign pointed to the centre)

Leaving them on charge all the time is not a problem, in fact with SLA's its probably best you do. Just disconnect the charger when in use. Its not a good idea to have them connected to the charger while they are being drained.

There might be a problem though charging them all at the same time. John will have to answer this bit. Chargers are often rated to charge a particular capacity battery. So charging three together might not work so well as it would be over the rating of the charger

Hope some of this is of help.

Thanks for that Dave.

I'll check with AP what the polarity of the connector is. Out of curiosity, what damage could ensue if the polarity was wrong? Or should I even ask that question ... :shock:

If I can't charge at the same time, would disconnecting them from each other then charging them individually be a reasonable plan?

Cheers
Dave

Dave,

Sorry, should probably have gone over this in more dept when you picked up the batteries.
1. if you haven't already got one go and buy a DVM (digital volt meter) from Maplins (cheapo €20 is adequate). Fully charged the batteries should read over 13V.
2. The charger I gave you is just a cheapo car battery charger, so it should be OK to charge 3 x 17Ah SLAs, but dont leave it plugged in / switched on when running the scope, as I think it's output alternates between 12 and 14.5 volts. Switch it off before powering up the mount.
3. As Dave Grennan said, connect them in parallel - i.e red to red and black to black.
4. The centre pin on the cigarette lighter adapter should be connected to the positive (red). This is the norm and I doubt that any manufacturer breaks this code.
5. If you do connect the wrong way round then I would suspect that most manufacturers will compensate for this by installing a diode on the input which will stop any input which is misaligned. (however I cant swear by this without seeing a circuit diagram of your mounts electronics.)

If you want give me a bell and I'll drop out and help you configure them, (as long as you don't mind four kids in tow). - No worries it's really quite easy, I'll bring along a soldering Iron and make the connections permanent.
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Just one more thing, never connect a partially dead battery to a fully charged battery, the charged battery can be damaged by this.

As for the kendrick, it does have reverse polarity protection, all the same, I wouldn't test it.

Like John said above, have nothing attached to the battery when charged except the charger.

John - thanks for the offer! I'm keen not to abuse your goodwill though

I'll give it a lash over the next week or so and see how I get on. I also need to double check the AP connector specification before I go any further.

But really, thanks for the info - spot on!

If I get stuck I'll give you a shout.

Cheers

Dave