Oh no! Another Power Tank project

[Horwig]

It's Autumn, I should be out under dark skies doing something creative, but circumstances force me to be constructive in other ways.

I have two imaging systems, a fixed obsy, which doesn't have good low South views, and a portable rig, battery powered.

We took a few spectacular lightning strikes around the field by the house last month, resulting in a lot of dead kit, including the obsy PC, and the Sitech controller on the big scope, so my obsy is dead for the time being.

This isn't me, but about 10 miles away: 

Also, three weeks ago they removed my Gall bladder, so moving heavy mounts is forbidden by shmbo!!!!!!!!!!!!!!!!!!!!!!!!!(    )

Now is therefore the perfect time to do some kit tweeking. I have been having issues with bias frames that don't cancel out on both systems for some time, and I've come to suspect crosstalk between the switching loads, ie. mount and dew heaters etc, and the camera.

My portable rig has been powered by a 22amp hour battery

It's been ok, but I'm sure I can do better, so here goes with a re-build.

The new supply will be twin battery, two 22 AH batteries, with only the negative terminal common. I want to keep the simplicity of the original, one box does all, but this time include the battery chargers in the design.

Rummaging about for a suitable enclosure, I have a camera case, used for an old video camera that seems to do the job, and a good fit for the batteries.

The chargers are Yuasa 12v 4a units, one per battery, again, a good fit in the case

A quick bit of woodwork, and this should do as the deck of the box, will need packing to keep everything secure, but at least this way, the chargers will get some airflow.

A quick bit of panel layout, It might all fit, left to right: mains in, then main battery fuses and charge/isolate/operate switch. Next will be two combined A/V meters (yet to arrive from China), with push button test switch , followed by two xlr outputs per supply.

The pwm outputs follow on the lower (dirty) supply, (that's the two phono connectors) pots and circuitry to come from the old box, one will be set at 50%, to supply the 12ac air pump on the desiccant system to stop the camera dewing up.

Missing is the 9pin d type for the focuser, the arduino will be inside, fed off the dirty supply, with an USB going to the 12v steel enclosed USB hub on the right, yet to be inserted into the panel, this to run off the clean supply together with the camera.

Batteries and chargers came from Batterymegastore.com No affiliation, but they have given excellent service, and their prices are extra keen.

I should leave everything now till the meters arrive, but if I get bored, I'll do a bit more on it.

Huw

[Horwig]

Got the woodwork done, the USB hub is sunk into the panel, the hole for the control panel is cut, and the support frame is in place to hold the batteries tight. It's wonderful the woodwork you can do on a mill...

Meters arrived from China Yesterday, I'd started on the work a couple of days ago, trusting the quoted dimensions on ebay. I reckon it looks OK.

The truth is that there's a lot still to do...

Carrying mounts is now a reality again, and the insurance company have come up with the cash, so the obsy electronics is on order, must be time for clouds again.

Huw

[astro mick]

That's very ingenious Hew,and a very neat job you,ve made of it.

Sorry about the strike,but it does look spectacular.

Mick.

[Horwig]

Well it's all done, now if that moon would only go away.

Huw

[ddtwelve12]

looks great have you got the ebay no. so I can have a look at the meters as ive got a 10 amp  12v bike battery that I want to use to power my goto scope and maybe put some dew heaters on eventually

[Horwig]

Here you go:

http://www.ebay.co.uk/itm/141197770442

It's item number 5, the twin colour meter

Huw

[Tinker1947]

I ordered 2 of the V/Amp meters they arrived ok took around 3 weeks, and there both red numbers...

[Horwig]

Beware, one of mine was out of calibration, read about 1.5 v high, so check against a known good meter.

Huw