HTN9013A Rapid Charger, Questions

[kb0nly]

First off... I know its been ages since i have been on here, just too much going on to ever get screen time, but i might be able to float around on here some more again!

Ok so here is the deal, i got a few of these HTN9013A rapid chargers, quick chargers, whatever you want to call them. They are for the SP50 series HT's. They have a red button on them that says push button for quick charge. But i'm not sure they are working correctly.

Drop in a battery or a radio and the led comes on and its Orange, tap the button and the led changes to Red but only when your holding the button down. The charge cycle never seems to complete and go to Green, at least thats what i assume they are supposed to do since it says Charging in Yellow, Complete in Green and Quick Charge in Red.

From the little info i could find online they should quick charge in three hours, after 9 hours the battery i dropped in to test it still shows Orange. And its a known good battery. So can someone explain the led and button better on these, i cant find any info online about them.

[WV8VFD]

Two of our chargers at work for our old SP50s that have been collecting dust do this. My good SP50 charger at home does fine though. I dont know why, wish I could help, but I am wondering myself.

[Al]

The schematic for the HTN9013A charger is contained in the service manual for the GP68. IIRC, the red button simply starts a 3 hour timer and switches the charger to high rate. When the timer expires the charger switches back to trickle rate. Since I can't put my hands on my copy of the manual right now, I'd suggest that opening the charger up and checking the value of any capacitors that appear to be part of any timing circuit would likely solve your problem.

[kb0nly]

Hmm ok, must be why these were set aside i guess. I will open one up and investigate. They do charge the batteries as a normal slow rate charger. Just would be nice to have the faster charge rate. I use these SP50's for family coms on MURS so i want the kids to be able to drop in and push the button and walk away.

[kb0nly]

Took it apart, no electrolytics in these, all surface mount. I had a quick thought though and instead of using the wall adapter i plugged in a test lead to my bench supply and dropped a battery in, went orange, tapped the button it went red and STAYED red. Sooooo... I am going to let it run its course and see if i get a complete charge cycle off it this time. Might have been a bad wall adapter causing the issue. I only got two adapters with these three chargers, maybe they already tossed one, the two adapters i got are rated 12v at 900mA and the charger won't go into quick charge when powered by them, but the part number on the wall adapter matches what i have found in the SP50 accessories list from a pdf brochure on the motorola website. So it is the correct adapter for these chargers.

Might just be a case of bad wall adapters i will see what happens now.

[Al]

Sounds like dried up electrolytics in the wallwart causing excessive ripple on the output. If you're able to load the output to 900 ma. with a resistor while measuring the AC ripple with a meter or scope that should show ripple to be excessive. A quick check would be to measure the DC output of an unloaded wallwart(not plugged into the charger), then unplug and watch the DC decay. If it goes to near zero in less than 30 seconds or so then likely the filtering inside the wallwart is insufficient.

[Will]

One of the tests for those chargers is measuring the DC current input. I use a current limited bench power supply.
They run off 12 volts.

What are your charger's current draw?

[kb0nly]

Not sure on the current draw, i didn't measure anything. Just plugged into the bench DC supply, my workbench has a 55a supply and battery backup to make sure i don't get a power glitch when programming radios or doing service work, etc. The charger went into quick charge with the 13.8v supply, after about 3 hours or so, i didnt really time it just happened to look over, the light went green. Charges just fine now.

I grabbed a 12v 2a power adapter from the junk box and tried it on all three chargers, worked on all of them just fine and the cycle completed as it should. So its definitely a case of bad supplies.