Ads
Forum Replies Created
-
AuthorPosts
-
If you are fairly electronically advanced you can make you own delta V charger for real cheap (i spent about $AU10 on parts). This can be fully customised to work with 1 to 26 cells and charging current for C/4 to 4C. I have set mine to switch off at -5mV and it works fine for these small cells. It does not get false reading from the car circuitry as it supplies the circuitry as well at the batt. Use the MAX712 or MAX713 chips. They will GIVE you 2 sample chips for NOTHING. thats right, nothing. you don’t pay shipping or anything. The chips retail for around $25ea on rs components and that excludes GST. Just an idea for the techies out there.
yes it is a voltage reg but with a feedback circuit. So I guess it is a current reg in a way. Difficult way to do things but I have a few add ins on the horizon so i am thinking ahead.
I use the pot to control the output voltage. Has bugger all current running through.
I too use a custom LM317 charger. I use a pot to control the rate of charge so I can do a standard quick charge like the controller or do a 5mA 12-16hr trickle charge. I am a tight ass so an intelli peak charger or similar was out of the question. For $1.80 for the LM317 plus a couple more bucks for the other components I have a charger that is pretty much indestructable (chip has thermal cut off). Get yourself a multimeter so you can check which positions on the pot are what rates.
With NiMH batts you should NOT fully discharge them as you should with NiCad batts. It is possible to over discharge a NiMH which does some serious damage. To stop fully discharging the NiMH batt, you need to take it out of the car or put in a switch. The NiMH batts have no major memory effects so you can half charge or fully charge with no side effects. NiCad’s on the other hand do have memory effects, ie if you do a full charge you should only fully charge it from here on, likewise if you do a partial charge you should do the same from now on. You can mix you charge rates around but the performance will change quite a bit.
With the smaller batteries, the longer more gentle (low mA) charges are better in the long run. I don’t like to do a full charge in less than an hour, but as long as the battery doesn’t get hot you can charge it faster.
If you think you batt is stuffed try putting it in the freezer for 24hrs then try it again. May fix your problem. (This works on Mobile phone batts too).
Dave,
I am in the process of making a charger with 4 independently operated bays (for different batt sizes). Will keep you posted.
Cheers
-
AuthorPosts
