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Powertank Project 2010


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I've done a new thread for this, so as things happen and it gets updated, people can instantly see what it's all about.

It might take a little longer than I hoped to get it all completed, and there could end up being a few different phases with additions from an initial 'ultra basic' spec. While such a spec could indeed be done without a voltmeter, as I consider a voltmeter to be the single most essential element for getting a worthwhile service life out of batteries (and they are not cheap - I got really lucky with a 35 amp gel one - but I will try and sort equivalents that are as near such good value as possible), and the one I sourced seems excellent value and well fabricated, it's in from the get go.

So far the voltmeter has arrived, the battery box has arrived, the battery is on the way.

I have a horrible feeling the battery box is going to be quite a bit too big for the battery that's coming. I'll take photos of it with the battery in it after it gets here. However, it is quite nicely built, has corner vents in the lid, PLUS, a flat lid area big enough to put at least one of the small solar panels on, to trickle charge the battery!

The base box itself also has small moulded in handles at each end.

I might just keep this battery box back to sort out a solar charging setup with a bigger battery more suited to its size. As even leisure batteries can die fast (a pal was on the phone earlier moaning that his year old 105 amp leisure battery in his caravan has died), a solar cell keeping them good could prove very cost effective. If say .5 to 1 amp charging can be worked out cheap enough, and would fit onto the lid space available, it might just be enough to keep up for casual astronomy use on holiday.

So as soon as funds allow, I'm going to order one of the small battery boxes I found later.

Sad to say I'm a bit brassic at the moment, having just ordered my ST120 from FLO (;)), but I'm finding some interesting stuff to incorporate, have found some very nice 2mm 17.5 amp wire (but getting 2 rolls - black and red - is going to slow things down a little too), some nice fuseboxes, nice 15 amp waterproof sockets, plus switches and LED's, etc., so I won't have forgotten about it, and am still looking around for other stuff that might be useful.

As a guide, I'm going to try and get things done and photographed for the very basic unit being up and running around mid March, and earlier if possible.

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Looking forward to seeing this develop. Do you have a parts list for the bits you've got already?

I'm after some female 12v cigarette lighter terminals so I can rig my mount up to my kendrick and just power the one device. Couldn't find any in maplins. Also interested in what yr using for fuses?

Michael

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Well, done a bit more shopping (it's sardines on toast for a few weeeks lol). Got the small battery case coming, which should suit the 34/35 amp hour mobility type batteries better.

New small Battery Box - Boat - Caravan - Fishing - 12v on eBay (end time 20-Feb-10 12:47:13 GMT)

This voltmeter:

12V Battery Voltage Meter, Voltmeter 11.0 to 14.7V on eBay (end time 09-Mar-10 15:33:18 GMT)

These sockets:

Motorcycle/Marine Waterproof 12 Volt Accessory socket on eBay (end time 23-Feb-10 23:41:52 GMT)

Fusebox is a 6 way (the link goes funny so ebay number 390152533124) and I'll try mounting that with low modulus neutral cure silicone (takes a bit longer to set, but is exterior grade and should do 30 years plus as a flexible adhesive).

Wire is going to be 2mm 17.5 amp rated, and two strands in shrink tube to the fusebox (as much as anything to toughen it up for movement when the lid opens).

Getting some self adhesive cable tie bases for 3.5mm cable ties which may be useful for always repairable hinges, etc.

Got some red led rocker switches coming to try with diffused red led lights. Some black flexi drinking straws to put them into (which will be reinforced with shrink tube). Etc.

Just noticed that the battery supplier has listed some more of the same for sale MK GEL BATTERY 12V 35AH MOBILITY SOLAR WIND CARAVAN ETC on eBay (end time 21-Feb-10 22:15:04 GMT)

By the way, communication with that battery supplier has been excellent, and it looks like continuing supplies of similar suitable batteries at a reasonable price, should be available.

I'm hoping the battery boxes will be a real nice fit with these batteries. Can't wait for them to arrive.

Edited by Ogri
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Ah nice one Merlin!

As soon as all the bits arrive, I'll know the sizes of connector to order (pre-tinned brass spade connectors).

Anyone know a reasonable priced source for them?

eta: as these are 15amp sockets, what amp blade fuses would be recommended? Would 7.5 amp be too high for the equipment to be run?

eta2: The battery arrived today (15th Feb), and very nicely made it looks too! It is a little too tall for the first battery box I got though, and the width and length leave a lot of spare room around it. Fingers crossed for the next box. Once that arrives, I'll do some initial photographs.

eta3: Power sockets arrived 16th (got 2, putting one on my motorbike), and are very nice; fuse box arrived, also nice, may be a bit big with the lid on - but don't really need the lid - and may take a hacksaw to it; shrink tubing arrived and looks suitable size wise; flexi drink straws arrived and seem up to what I want (with shrink tube for toughening); and self adhesive cable tie bases have arrived.

Edited by Ogri
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Cheers Merlin!

I must have been looking in the wrong place... I do like the look of the waterproof click fit ones though from the ebay site suggested by Ogri.

Marine Waterproof 12V Accessory socket - Chassis mount on eBay (end time 22-Feb-10 12:42:48 GMT)

I'm not sure I'd get enough Amps from a battery for heaters, cam, guider & mount. It totals at around 5Amps and that's before I try and use my car adaptor for the laptop. So I'm thinking of making a field obs utility table with one of these AC/DC converters housed inside a box with the 240v cable passing through a gland and back into the safety of the tent and obviously via a RCD.

13.8V 15A/18A Max Switched Mode PSU : Bench Power Supplies : Maplin

That way I can keep the DC cable runs down.

TBH I'll probably keep the whole thing in the tent so then I can use a lighter red screen and it'll be easier to image without disturbing others at star camps.

I'd be interested to hear what others do.

Mike

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Yeah, I'm considering that one too... I'm just thinking that I may want to run a 12v fan to remove ep dew. 2" bands don't stop people breathing on them!

I'm also looking at these: Power Supplies - Moonraker UK Limited

...but i might be being drawn by the fact that the shop is called 'Moonraker', oh and of course anything with a dial looks more impressive! ;)

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I was just a little concerned that it's fixed at 13.8v though. My mount states operable voltage between 11-15, the guider is 6-14, but my Kendrick Digifire just says 12v DC.;)

oh, and I should apologise for hijacking this thread.... ;) I'm really looking forward to seeing you're mobile solution, I'll keep you posted on my hookup version. :p

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Well the 13.8v is the 'proper' level of 'healthy' 12v, so to speak. Which is why a voltmeter is so important.

When a battery is actually down to a 12v charge level, is very much the time to power down and stop using it. From 12v, the voltage plummets precipitously fast, and it can get into a deep discharge state before you blink (when all the damage is done - even to deep discharge batteries, but they 'recover' better).

The small battery box has just arrived by the way, and what a GEM! ;)

It's an Attwood Sea Guard, made in America, and beautifully made ( Battery Box Small : Boat LED Lighting, Gas Springs, Marine Hardware, Bimini-Tops & Covers : Attwood Marine Products® ).

The 35 amp Gel battery fits in nicely with a good gap all around (so easy enough to grab the battery) and the internal height leaves plenty of room for sockets, fuse box, etc.

As soon as I have charged some batteries for the camera (er *koff* found them first rather), I'll take some piccys.

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Hi Orgi

Ive just built a power box for my auto dob 12 volt, i was very worried about overchargeing the batt or melting it so i went to maplins and got a little timer kit £7.50 ive got it set for 30 min's so even if i go out it cut's it'sself out worth putting somthing like that into your box. I'm trying to get my son to take photos and get it put onto stargazers for all to see so hopefully soon. It has cost me under £25.00 and it can be charged from a car lighter socket But the dob with it's fan motors and handset use very little power so i get a lot of use before i have to chargeit again

Robert

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That sounds good Robert! As I'll be using a Gel 35amp in mine, and they don't like over about a 5 amp charge rate anyway, so for now, all the charging is going to be done with a 'plug in and forget' trickle charger which only puts out 0.6 amps. Once the battery is fully charged, it then auto switches to battery conditioning and maintenace mode. It's one of these Oximiser Battery Charger (darn just noticed they have gone up a tenner :eek: ). Though this new arrival does look suspiciously like the same thing at the previous offer price Tech-7 Battery Charger

I don't actually have anything to use the powertank on as yet (but dad's started getting some DSO photography ideas lol!), so will likely just use it to drive some switched red LED's for the time being, and the trickle charger will be able to keep it easily topped up.

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  • 2 weeks later...

Just tripped over something on the net that looks a good deal. It uses the same battery box as the small one I got (very nice quality) and all the work is done, just about.

The only thing it lacks is the voltmeter, which is cheap enough and easy enough to install anyway.

Numax - Numax Deluxe Battery Box, Price £43.67, UK

Probably slightly cheaper than buying the bits separately and putting them together yourself. :)

eta: even cheaper here http://www.everything4walking.com/acatalog/info_MNACCUBOX.html

eta2: my Oximiser battery charger turned out to be a duff one, and it's destroyed two motorbike batteries. :(

Edited by Ogri
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Also take a look for a range called "vantec stealth" and also 'papst' who are arguably one of the best fan makers do a quiet range.

Yes very true TH - see what's best value at the time of purchase is what I do, if there's offers on anything.

On the powertank project itself, given what good value those ready made heavy duty battery boxes are, I'll do some detail snaps of mine and keep them to one side, then if prices ever get silly, I'll do a post with it all in. Just waiting to get some Low Mod Neutral Cure silicone before doing my own (dead motorbike batteries have basically messed me right up at the moment, sad to say).

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There's some dealers do REALLY good prices on papst on the bay, I know when I was doing my extreme PC projects there was a lady ran an ebay store, mostly dealt in papst and she could quote all the cubic airflows and db levels for every papst fan and tell you how many bearings and what sort of bearings were in each one AND what minimum start voltages were and what resistors to put inline to get the best out of them, she was AMAZING!

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There's some dealers do REALLY good prices on papst on the bay, I know when I was doing my extreme PC projects there was a lady ran an ebay store, mostly dealt in papst and she could quote all the cubic airflows and db levels for every papst fan and tell you how many bearings and what sort of bearings were in each one AND what minimum start voltages were and what resistors to put inline to get the best out of them, she was AMAZING!

That's what we like to hear! :headbang:

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  • 2 weeks later...

Hi Ogri,

Just wanted to say thanks again for the links and advice from those on this thread. I managed to get my power box sorted and it survived its first field test at Kielder.

Some photos attached.

Mike

post-17582-133877433444_thumb.jpg

post-17582-13387743345_thumb.jpg

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