hi, after some schematics to charge 6 volt and 12 volt sla ( sealed lead acid ) batteries.... basically dont need to charge them flat out , cause they dont get used much, something i can leave on trickle charge for a week or so , would be good....
any body have any or know of any links ?
Go to 'jaycar' spend $59.95 and buy one of these.
No point in messing around getting the parts and building one. Probably cost more.
Just check the rating you need before you buy.
"Martin"
Jaycar have this charger for SLA batteries:
However, WES have 1 amp SLA chargers in 6 and 12 volt for less than half the Jaycar price.
.... Phil
hi, thanks, but i really want to make one not buy one, i reckon i`ve seen one using a lm317 , but cant find the schematic , and it would have cost only 4 or 5 $ !!!
i`ve got a heap of electronic conponents , so i`d rather use them , than keep buying ready made stuff.....
mark k
Just make the usual LM317 circuit, but 100 or 120 Ohm resistor for the output to adj terminal to soak up the quiescent current, and put a series diode from LM317 output to battery to stop the battery powering up the charger when the mains is off. Appropriate R and trimpot from Adj to ground for desired output, add a switch for 6 and 12V operation -- no magic there.
Set output voltage for say 13.5V float on 12V, half that for 6V battery, only need small heatsink on the LM317.
The schematic is basically from datasheet with the extra diode and lower Adj resistor. If you want reverse battery protection, add another diode from battery minus to the series diode's cathode, and put in a polyswitch or normal fuse to the battery.
Grant.
-- http://bugs.id.au/
8
No doubt you have a reason to state the above. But I just contacted 'jaycar' and they informed me that the above was fine on SLA's on a the trickle setting. But then you never know I suppose. Don't think I'll bother next time.
Those suggestions are nice, and cheaper than the DIY method, are a lot easier, probably a lot better, but they don't help the original poster with his school project.
His suggestion of using an LM317 adjustable regulator is probably the more expensive option other than a fixed regulator which is cheaper, and that you can regulate anyway.
It smells like a school project, and non-compliance with component requirement would result in a fail.
Remember, his quoted prices of $4-$5 is component value only (and I think is still overestimated) and of course does not include heatsink, power supply, wiring, clamps, connectors, case etc, because the school is only interested in the design.
Unless of course Mark can show he *can* build it for $4-$5 complete, instead of the commercial ~$30 or so. In single quantities of course. In bulk orders, China can build them for less than his quote anyway.
He's probably right on this one. (odd, I'm on Phil's side for once..).
Be careful what you state about Jaycar gear unless you test and evaluate it properly.
The term "trickle" when it comes to lead-acid batteries can mean MANY things. Usually it means a less-than-full charge rate that is selected when the full rate charge is over. In other words, if you leave it long enough, you will fry your battery anyway.
What you want, is a float charge. If they *meant* a float charge, they would have SAID float charge. And in fact, they DO say float on some of their other chargers.
The SLA battery may not "explode", but at the end of the day, there's little difference between "explode" and "molten mass of toxic, corrosive goop all over the desk".
But hey, it's your money.
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I don't know about him but for SLa I'd aim at C/20, so they would be fine for 160AmpsHr SLA (and at that size you could buy twice the capacity of simple Deep Discharge Lead Acid batteries(at a decent battery seller and not chains).
What was the current of the trickle current? That is the catch 22. IME, most SLAs are small stuff and the Jaycar plugpack SLA (@375ma?) can stuff those if left on continuously.
What level and what subject would they do this?
"Martin"
But unless the SLA is a VERY large example, that 8 amp charger will certainly damage it on either setting.
** Despite appearances, battery chargers that work well, are safe for the battery and the user under all conditions are NOT trivial designs.The AC transformers used in mains powered types have to be sized just right for the intended battery type and also must meet class 2 insulation and safety requirements - they are "prescribed items" under the electrical safety laws for that reason.
You are NOT likely to find anything suitable in your junk box !!!
Lead acid car battery chargers are NOT safe with SLA batteries, or any other type AFAIK.
It is very much a game of horses for courses.
.... Phil
Subject? Er, when I was in school they called it "Electronics". Who would have thought? And that was starting in year 8 or 9 I think.
As far as level goes, this would require complicated mathematics involving multiplication AND division, also with addition and subtraction. So that would be around year 10 or so?
As long as you can teach the principal of voltage offsets, past that, the above maths apply.
But half the time they never bothered to properly explain theory of operation either. Shut up, here's a project, make the board and put it together.
A pass if yours flashes the lights in the correct order, and an automatic fail if you ask stupid questions like "what does it do?".
They don't teach you, (and you don't have to know) the detailed workings of the inndards of the component you're working with, basic theory of operation is enough to get you by for now.
They taught us all about resistors and capacitors, but I didn't really get to know all the implications of each type till well into my career. And even then, the importance of some types over others in specific applications. Especially the more common applications where you might know *why* it's there, but not that you should be using a particular grade of component there regardless of the fact that "everyone else" appears to use garden variety.
My point being, perhaps not with "school" but with private tutoring, you can get on your way with apparently complex components in albeit non-critical applications very early.
mmmmm * found * a circuit, using a lm317, 3 resisters, 2 capacitors , which i think comes in well under 5$
i wasnt talking about the transformer , only the circuit,,,,
its not a school project , and so what if it was ????
I'm not doing your homework for you.
The answers you seek are available on the net, which you clearly have access to since you're posting on newsgroups.
On Wed, 9 Jun 2010 13:14:58 +0930, "mark krawczuk" wrote as :
Try take a look at the C200 data sheet, you can make a charger from schematics on there with settable max charge rate AND settable max V with this chip - total cost of charger probably around £10. If C200 are still available! Much cheaper if you use a C200 ic plus bits out of your scrap boxes! Charlie+
On Thu, 10 Jun 2010 08:04:06 +0100, Charlie+ wrote as :
Sorry in above post - for C200 Read L200 and here is any ole website from search, with schematic ....
As John said. It is basically my undestanding of the level at which this might be YOUR project. In which case, you should be able to do something as basic as search the internet and find a circuit that could be used and/ or modified.
The point about school work is that you should do the work and learn from it and this is actually a good project for that. You do not learn much, if anything if it is dished up to you.
Well, that has been given to you anyway. Now your job is to build it.
Good luck.
Wow, something useful,,,, or not. I thought it was mostly mickey mouse subects now.
Circuit analysis, 2nd year uni for me.
Yes.
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