I've got a little spare time here at work today so I ran a simulation to us e welder as interface between 120v line and 12v car battery. It looks like I can probably put welder on 120v line with a single phase diode bridge on it and use current knob on welder to control current to charge 12v battery .
Am I totally nuts or Mcguyver?
What does the current knob on that welder actually do? Change transformer taps?
Probably sliding magnetic shunt. So OCV drops and LL skyrockets when it's down.
I would use 200V diodes absolute minimum, and put an MOV on the DC output in case it ever goes open circuit under load.
If you put enough diodes together in parallel, you can also do DC welding!
Tim
yes. The most important part of any battery charger is charge termination.
use welder as interface between 120v line and 12v car battery. It looks l ike I can probably put welder on 120v line with a single phase diode bridge on it and use current knob on welder to control current to charge 12v batt ery.
I have no idea.. I have a buzz box out in the barn. I think I've got an AC /DC switch as well. The first time I plugged it in it just made this growl ing noise. The previous owner mis-wired the power plug. Scary.
George H.
use welder as interface between 120v line and 12v car battery. It looks l ike I can probably put welder on 120v line with a single phase diode bridge on it and use current knob on welder to control current to charge 12v batt ery.
Well, if it's a Lincoln, the knob is coupled to a piece of core it moves in and out of an air gap.
mike > The most important part of any battery charger is charge termination. I've learned a lot in this usenet group about intelligent charging systems, from JT and some others. Clearly the way to go. But I've seen nothing about dumb trickle charging. Is dumb trickle charging bad for NIMH batteries? Is there a low level where trickle charging is OK for NIMH batteries without ceasing the charge? Whereas the old lead-acid car batteries could be "maintained" with a transformer a diode and a resister, do the newer battery chemistries react badly to that?
It's very, very low, around the level of self-discharge.
There's plenty of information in the battery maker's manuals- that's really what you want to read carefully when you're designing a battery charger.
Best regards, Spehro Pefhany
I'd use 0-deltaV termination with normal charge current. Then put the charger on a timer to replenish the charge lost due to Self Discharge. If you've got LSD cells, just put it on your calendar to do it manually every year or so.
'cos those cells so trippy ;-)
Usually the term "dumb charging" means charging at C/10. That's fine for NiMh - until the cells reach full charge. After that, C/10 can cause damage over time. If you reduce the rate appreciably - say down to around 10 mA - or terminate when fully charged, the damage is avoided, but I suppose that no longer qualifies as "dumb charging".
Ed
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