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You are right about the polarity. As I said in my reply to Display Name Taken, below, I luckily managed to open the bugger, and the symbol on the PCB under the LED confirms centre is +. It also has a another diode though, I presume for some protection against reversed polarity.
No object is so beautiful that, under certain conditions, it will not look ugly. - Oscar Wilde
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In that case you may have no option but to use a variable voltage/current bench type PSU then. If its a lead-acid style battery that's been left at a low state of charge for a long period then the battery may well no longer take a charge.
What voltage is the bulb, that may help you with setting the PSU voltage?
You should be OK to start with charging it at a maximum voltage equal to the bulb voltage rating and 50-100ma current limit.
Supervised charging would be a good idea too at least for the first charge.
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Oi. The bulb is an array of 18 LEDs.
No object is so beautiful that, under certain conditions, it will not look ugly. - Oscar Wilde
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Overjoyed, I discovered some small screws I didn't see the other night, under dimmer electric light. It is in fact two sealed lead acid batteries, that have been at a low state of charge their life with me. They do give a "constant voltage" (maybe DC translated from Chinese?) charge of 4.8V - 5V, and standby of 4.5V - 4.5V but are connected in parallel. I doubt a low current (850mA) 9V charge would blow them up, but now I know what to aim for.
No object is so beautiful that, under certain conditions, it will not look ugly. - Oscar Wilde
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They are probably 2 cell batteries, you need around a 4.8v supply that should be current limited. When the batteries are charged (terminal voltage reaches 4.8V or so) the current will reduce to zero. Your 9v supply may well boil the electrolyte, depending on the current it supplies.
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They two look like two cells each. I don't understand what you mean though. Will my 9v supply boil the electrolyte before current reduces to zero, with a lower current limit keeping the electrolyte safe until "the current will reduce to zero"? Current is pulled, not pushed, so if it reduces to zero at 4.8V, my supply can't "push" more current in.
No object is so beautiful that, under certain conditions, it will not look ugly. - Oscar Wilde
modified 13-Mar-15 12:12pm.
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Yes you are correct the battery will keep pulling current beyond its charged state from your 9V PSU, its terminal voltage will keep rising and it will effectively be overcharged, or the PSU will burn out first as it will be supplying at least its rated current during the charge.
IMHO you need to either find the correct PSU or use a voltage/current controlled PSU. I would imagine that the battery may be useless anyway from being left at 0v for a long period Lead-acid batteries don't survive this condition very well.
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Yep, they've been at least about two years since I bought it, and I really only switched it on then, to see how effective it was. At least they look low cost and easy to replace.
No object is so beautiful that, under certain conditions, it will not look ugly. - Oscar Wilde
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Brady Kelly wrote: soldering iron duct tape Just forget about the engineering degree, if you keep making uber-gaffes like that!
I wanna be a eunuchs developer! Pass me a bread knife!
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You got any duct tape small enough to apply said tape down a 5mm hole? A good old spot weld with a hot iron always does the trick.
No object is so beautiful that, under certain conditions, it will not look ugly. - Oscar Wilde
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*sigh*
You've got so much to learn.
I wanna be a eunuchs developer! Pass me a bread knife!
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Hey, it has crossed my mind to use a roll or two of duct tape to dampen any really sudden expansion of the 4V batteries, from too much gassing when charged at 12V.
No object is so beautiful that, under certain conditions, it will not look ugly. - Oscar Wilde
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Ah, so that you can have a controlled release of the internal ether. Very good. You're learning.
I wanna be a eunuchs developer! Pass me a bread knife!
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I had my first controlled hydrogen "explosion" before high school. I generated hydrogen by reacting zinc from 9V zinc-carbon batteries with pool acid, and collected it in a balloon or something, then threw something burning at it as it hovered around.
No object is so beautiful that, under certain conditions, it will not look ugly. - Oscar Wilde
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My favourite memory of batteries is from when I was in the sixth form, doing A-level Physics.
Our new (although he was as old as the hills) Physics teacher, who was completely useless at teaching (the three of) us, had just got the school to splash out on hugely expensive, transparent energy cells (or "pretty batteries", if you prefer un-hyped speech).
So he got us to connect some circuit up (I'm pretty sure it was a Wheatstone Bridge, but we did so much circuit-connecting, back then, that I may be confusing events) in the lab, and we left it to soak, going off to the be-desked room next door to go through the Maths of it.
As we left the lab, I switched a couple of cables.
On returning to the lab, we found that the beautiful, new, hugely expensive power cells had turned into beautiful, new, hugely expensive molten slag on the inert, near-indestructible bench-top.
I often think back to that day. It brings me great happiness.
I wanna be a eunuchs developer! Pass me a bread knife!
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Sounds like us replacing fuses with nails on the wiring boards in the Electrician Work shop in school, contributing I don't know how much insulation smoke to the atmosphere.
No object is so beautiful that, under certain conditions, it will not look ugly. - Oscar Wilde
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Not so. Cheap chargers do not include voltage regulators, and require the correct charging voltage. Arbitrarily plugging any old charger block into the thing is very likely to let the smoke out of the battery.
Will Rogers never met me.
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Especially with finding the batteries only being rated at 4V, way too far below what I'd feel safe with on 12 car charger, which is what I'd starting thinking of.
No object is so beautiful that, under certain conditions, it will not look ugly. - Oscar Wilde
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I want to update one of our projects from .Net 4 to 4.5 to use some of the new features, but a lot of the clients using the program still run on XP Embedded, which can't install .Net 4.5
And if if I could make the change, it would require all clients to install .Net 4.5, something that might not sit well with some users.
This also raises the question of sticking with what works vs keeping up with the latest trends (an almost impossible feat).
I have at least switched from VS 2010 to 2013 CE.
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I think that if you are running VS 2013 you can't even target .net 4.0 on XP, please correct me if I'm wrong but I swear I read that somewhere.
.net 4.0 isn't that old though, at least you're not stuck on 2.0 or something! The main thing in 4.5 is async/await, and you can use it in 4.0 with the Async Targeting pack from Microsoft.
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I'll have to test that, but using .Net 4 compiled w 2010 works fine on XP.
Yes, at least it's not that old
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Maybe it's C++ I'm thinking off
But when targeting 4.0 on a machine with 2012+ installed, I think there's some gotcha about bugs though because 4.5+ replaces the 4.0 compiler and bugs present in 4.0 but fixed in 4.5+ won't be apparent when debugging on your own machine, but things can crash and burn on the target machine. Something to keep in mind!
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Thanks, I'll definitely have to test before deploying.
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Yes, the only really big deal I've seen with 4.5 over 4.0, in my recent baptism of fire, is async/await . But as @JMK-NI notes, you can still pull the same tricks with a small workaround. And they are pretty cool tricks.
No object is so beautiful that, under certain conditions, it will not look ugly. - Oscar Wilde
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The async / wait is exactly why I want to upgrade. At least our server side has a min requirement of Server 2008, so I can update that to .Net 4.5
We are also doing a major update from v1 of our SW to v2 which requires a reinstall because we changed the update mechanism and a whole bunch of other stuff. This would have been an ideal opportunity for the .Net upgrade as well.
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