How do you join two batteries together?

[Fay]

At last deep sky camp, Ian told me that the transformer, I was using, also takes power from the battery. I am thinking that I had not fully charged them as I ran out of power. He mentioned joining the two together, & it must involve eliminating the transformer.  Can anyone please tell me how to do this?

Thanks a lot

[JohnP]

Fay - I don't understand what you are trying to do...? Can you take a photo of current setup or explain in more detail? What transformer are you on about?

John

[Fay]

I think it is a transformer. I will tell you when I go up the garden.

[Mac]

Er., Transformers dont work on DC, sure you dont mean an inverter?

unless you meant one of these,

[Mike]

Unless you want to increase teh voltage from 12v to 24v you will need to wire them up in parallel fashion.

Like this :-

[Mike]

No, seriously, like this...

[Fay]

Yes I meant invertor. I was using one battery for laptop & SX & the other for mount, but was told that it may be better to join the 2 batteries & use then in one lump, as the laptop+ camera one, was runniung out before the other one. Although I will use the Atik now, which does not use a plug.

Mike very funny picture above especially all those batteries!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[Mike]

I would love to know what he was using those batteries for. They are wired in series which would give you around 420V !!!   

[Mac]

he might have been trying to do this, but wired them wrong.

http://video.aol.com/video-detail/submarine-battery-bank-shortedinitially-called-ball-lightning-now-leidenfrost/3491664736

[Ian]

I reckon welder...

Fay, you would need to wire them in parallel. That is connect all of the + terminals together and all the - terminals together. If you go + to - then you'll either end up with 24V, 36V, 48V or some other multiple of 12V or a fire...

Just bear in mind though, once they go flat, they're all flat and you're then stuck

[Rick]

Welding's certainly a possibility with that lot!

Generally, if you're going to connect batteries in parallel, it's a good idea to use identical batteries and charge them as close to exactly the same as possible...

[Ian]

while that's best, I would think for our use you'd get away with different batteries together as long as you charge them all up separately. If you charge them together in parallel then you stand a chance of frying the weaker batteries before the strong ones charge fully.

[Fay]

I am thinking that I will stay as I am. Knowing my history I could have a mother of a fire at Tuesnoad!

[JohnP]

Fay probably a wise decision....

The mount probablys draws something like 1-1.5Amps (depending on scope loading) You Atik camera is something like 0.75Amps & the laptop is probably about 3-4 Amps.. .

I would probably keep the mount on a separate battery (just to guard against power clitches etc.) - The camera & laptop should be no more than 5A so on something like a 80Ahr car battery assuming 75% usage you should still have something like (80X.75)/5 = 12hrs from a full charge which I would have thought would be OK for an average 2nights of DSC iamging.... You could always run your mount off battery A the first night & the laptop & Camera off B & then put camera & laptop on A the 2nd night & mount onto B....

John.

PS - I am assuming you have 80A/hr car batteries & aren't using AAA's.....

[Mike]

I always use one battery to power the mount and another to run the laptop and camera.