I'm looking for one of those little panel meters to be used for monitoring the charge / discharge rate on my garage solar lighting system please [1] (around a tenner would be fine).
Everything seems to be digital these days and whilst I could build a little monitoring panel showing current (shunt resistors etc) I think an analogue meter would be more suitable (in an analogue watch or rev counter sorta way).
Cheers, T i m
[1] The charge controller I'm using has LED's indicating battery voltage (red, amber green) and solar panel charging or not. I could put a 0-5A meter on the input side but that wouldn't also show the battery discharge rate (handy when experimenting with different types of light).
I did something similar many years ago, building a sort of poor man's UPS. I had an old 50uA movement, and the shunt was to simply connect the two terminals to the battery lead about 30cm apart. A bit of experimentation was necessary to get the calibration to match the meter scale.
I opened the meter up and changed the zero setting, so it became a 5-0-20 ammeter. You have to be very careful opening moving coil uAmmeters though -- sort of need a clean room mentality as they're very susceptable to tiny dust particles getting in and making the movement stick, especially anything magnetic.
As you say, the first examples are a bit pricey (for this project anyway) but I like the idea of the two meters. ;-)
So that would be each meter in series with a suitable diode in reverse / parallel with t'other? I'm not sure if the .6V or so I'll lose across the diodes with affect anything?
Hmm, that's quite neat .. and as I'm really not looking for actual values (I'd use my DMM for that) I can calibrate it to suite whatever charge / load combination I end up with (without having to remember that 8A actually = 5A etc). And I like the red / green bit .. very 'obvious'. ;-)
Shouldn't be a real problem as I think I still have some Eureka wire left over from my racing EV project (and I even know where it is in the workshop!). ;-)
Now that's a handy link, ta.
I was actually looking for such things on eBay this morning but didn't come up with much.
Remember the days when we bought and fitted such things in our cars ... paneling over glove boxes. What were they, Volts, charging Amps, rev counter, manifold vacuum, engine temp ... and who typically made them ... began with a 'Y' was it? (I had the set in my Moggy Minor van). ;-)
I really miss a temp gauge in Daughters Ka (especially as we know there's a small water leak (we have a new water pump waiting). :-(
I did similar with a DVM on my electric racing 'motorbike'. So many inches of the main battery feed cable gave me enough volts to feed the meter via a trimmer and to be able to calibrate it easily.
Very specialised. ;-)
I bet!
Well, I'll keep that idea in mind if I can't find anything off the shelf.
Well, they are about (it now seems) but just more expensive than I remember? This was the sort of thing I think I remember picking up from Tandy for £1.99 .. ;-)
Which I think is a little rich for this 'economy' project I'm afraid Dave. In reality anything I add in-cct isn't going to make the system more efficient so would only be there to give me a better feel of how things are performing.
Like: This morning I wired up a 15W panel to my eBay 10A charge controller [1] (pretty neat unit for £16), a fairly good ex UPS sealed
12V / 17AH battery and 8W test lamp. I stood the solar panel in a South facing window and the 'solar charging' LED didn't go off for most of the day. What I didn't know though was how *much* charge I was getting and how much difference things like a change of angle of the panel made or how much better it was not behind the double glazing etc.
A mate also picked up 3 more of those caravan / camping 8W fluro lamps for me today and I'll jury rig them and the rest of the kit in the workshop tomorrow.
Cheers, T i m
[1] If you leave the load on the controller it won't allow you to turn it back on until the battery voltage is above 12.5 and will allow it to come back on automatically once at 13.1V (if you left it on etc). Open / short cct protected, LED's for panel, battery and load, built in load on/off switch.
[2] How do they make and include the tube, electronics, rubber end caps, ciggy lighter plug, pair of crock clips, 3m of cable and a stand for £6.99.
Hmm, I had a look this morning and couldn't find much and I've looked again a found a few more this time.
There are some reproduction 12-0-12A ones (made in India) for about a tenner and although they would certainly do I don't suppose I would see much movement on the needle with my existing setup (I may expand it later so ... ).
The 8-0-8 ones aren't cheap either and for the same money I could go for a 0-10A digital and shunt (in light of the cost of some of the analogue ones may be a second option). Not as 'nice' to read but actually displaying specific (calibrated) info.
Ok, well thanks anyway and I'll put it all in the pot. ;-)
The sight in my remaining, properly working, eye does not allow me to read a digital watch with my glasses off. When lecturing, I can't see the audience with my glasses on!
Yaeger? Smiths, too. I had an Anglia (105E) with a complete fibreglass dash, that fitted over the original dash, complete with moulded areas to house meters. I'm sure there were moldings for three meters above dash level, plus three more below. Speedo and rev counter behind the steering wheel, then, top right and bottom right some combination of fuel gauge, volts, amps, manifold vacuum, water temp and oil pressure.
The fuel gauge was the standard Anglia unit, butchered to fit inside a round housing, so all the meters matched. Oh, happy days, but all fairly pointless :-)
Since I reached 50 I've needed reading glasses (ready specs) for closer work and a stronger pair for real fine stuff. Without glasses I can easily 'see' [1] the time on this 20 yr old Seiko but there's no way I can read the day / date. :-(
But hey, the days seem to pretty well follow on anyway so it's not a problem. ;-)
T i m
[1] As in you glance and get a rough idea of the position of the hands and the rest seems to happen subconsciously. It seems different when someone asks you the time and you try to give an accurate answer?
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