DC Pulse Battery Charger

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DC Pulse Battery Charger

Post by guitronics » Sun Nov 21, 2004 5:19 am

I need some direction towards a DC to DC Pulse Battery charger. I need a way of pulsing
(high frequency 1 khz. or more) and current regulating (Unity to lower) 14V.D.C to 18V.D.C. to charge Deep Cycle Batteries.<p>Total current output need not be more than 1 amp or so.Output voltage will be adjustable from 14 to 15 V.D.C.<p>Any ideas? I was thinking of a 555IC for generating the frequency? Thanks.
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Re: DC Pulse Battery Charger

Post by jwax » Sun Nov 21, 2004 5:44 am

So long as a square pulse meets your needs, a 555 driving a power MOSFET will work.
Curious, but why the high frequency? Why not a conventional charger?

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Re: DC Pulse Battery Charger

Post by fsdenis » Mon Nov 22, 2004 12:38 pm

guitronics:<p>Please see the "current source" thread initiated by Rosborne.<p>There may be some things in here you can use depending on what you may be trying to do.<p>If any of my stuff looks useful, I can move it to your thread to avoid excessive clutter.

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Re: DC Pulse Battery Charger

Post by kell » Tue Nov 23, 2004 1:34 pm

Put a mosfet or igbt in series with an inductor, running the mosfet off a 555. You can run the whole circuit off ~12 volts. The 555 hard switching the mosfet will cause pulses from the inductor. You need to set the switching on time so that the inductor stays below saturation. Direct the pulses from the inductor into the battery bank through a high speed diode. Naturally the battery bank and diode are oriented for the polarity of the pulses to charge the battery bank, so the diode also acts to block the battery bank from shorting through the coil.
It shouldn't be hard to regulate. You can use the base-emitter junction of a bipolar transistor (maybe with a zener in series) and compare it to a voltage divider on the battery bank. When the battery bank voltage exceeds your setpoint the bipolar turns on and grounds pin 4 or pin 5, whichever you find works better. Just some thoughts off the top of my head, I've built circuits like this.<p>There is a circuit that is only slightly more complicated that what I just described, which will allow you to pulse a battery bank off itself.
This is a discussion board. To see circuit diagrams follow the links on the shaka.com page, a prominent link on the bulletin board.
If you use this kind of self-pulsing circuit, you can trickle charge the battery bank at the same time.

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