electro900k,
Unless I’m looking at that pix of your Dustbuster batt pack (the part in black plastic) the wrong way - you are saying that the batt pack is only a 9.6-volt (as in 8 Ni-CD cells), but yet your wall adapter is said to be a 15-volt (AC I guess - as you still haven’t clarified that part). It would indeed appear to be AC - as by your Charge Pulse circuit schematic you had posted.
In looking at that pix of the black batt pack it somewhat appears that it might be at least a 12-volt (10 cells) or possibly even a 14.4-volt (12 cells) batt pack, but it’s hard to tell just looking at that black cased pix, as the black batt plastic case makes it look kind of deceptive. The latter 14.4-volt you can all but rule out, but the 12-volt you can’t.
Reason I say that is because I sell 12-volt AGM batt float chargers esp spec’d out at 13.5 volts for any 12-volt VRLA batt (AGM or GEL cell), as well as for all 12-volt FLA batts such as standard car batts, and Deep Cycle batts. The wall adapter part is outputted at 15VAC @ 600ma max output, and the DC charge chip brain part is limited to 500ma at a perfect 13.5 volts max.
Again - a bit more complex (sophisticated) then your simple 3-diode series pulsed DC current circuit you have there. That’s why I think the ~13 volts DC across your 9.6 volt batt pack seems a bit high! At full charge your batt pack would be at 11.2 MAX is why. Whatever the charge LED pulls through the batt pack at full charge is less then 60ma anyway. Probably it’s closer to 20-25ma if you measured it series wise IN CIRCUIT.
That’s hoping that those 2 & 12 ohm resistors are to spec!
If I had to bet money on it I’d say it’s a 12-volt DB, as that makes more sense as to the charge circuit and it’s float voltage. If it is indeed a 9.6-volt DB then I guess they figured in a faster charge rate, which also heats the batt pack a bit more as well. Shorter life span is all that way!
Have you physically taken the black batt case apart to check each batt call separately? If you haven’t you might be fooling yourself!
Is the actual batt pack voltage stated on the batt pack anywhere, or on the DB itself as to the real batt voltage of the batt pack? Somehow I can’t see the batt pack only being 9.6 volts. Not when the charge circuit is set up to float the batt at roughly 13 volts after being fully charged.
As for (dhoke) and what you added about getting somewhat ripped off on having to buy a new batt for your 15.6-volt DB when it really didn’t need one - as related to that broken 10 ohm resistor - that coming after the fact as it were! At least it is charging fine now! Too bad you didn’t catch that bad 10 ohm R sooner.
As for your Power ON LED there not working - you said that you dropped the DB at some point? Was that charging problem right after you dropped the DB as well or was the dropping part and the LED after you repaired and R&R that bad 10 ohm R??
It’s possible that you broke the LED’s current dropping R as well. That or you may have even cracked the PCB and caused a loose solder connection - as to the LED or R or both. If the LED was exposed to being above the DB’s case and somewhat stuck up and out a bit, and it was struck - when you dropped it - then it’s possible you just broke the LED itself at one of it’s 2 leads internally.
They are easy to test out - as all you do is use the DIODE test setting (roughly 1.5 volts DC) on your DVM, and then touch the probe leads properly to bias the LED, and if it lights up then the LED is good, but the current dropping R may not be.
Other then that I doubt DB puts much of anything sophisticated into their small cordless vacs. Pretty down and dirty cheap by design. I ran my older 6-volt DB model for over 15 years until the original Ni-CD batt pack died one day, and then I just rebuilt it for $4 with 4 surplus Ni-CD batts, and it lasted me another 10+ years and then the motor windings shorted from old age. For a $3 garage sale item I got my moneys worth out of it.
Now I just use my Ryobi 18-volt model C/L hand vac that I got for free. When Ryobi first came out with those multi tool kits there was such an abundance of their vacs that people were practically giving them away. I just traded for mine as that is how I got it for free. Otherwise they can be had for $15 on Craigslist. The Ni-CD batt packs are pull out type and they are 1 hour charged with their great base charger. Very well designed and built charger I might add!! They too can be had for like $10 on Craigslist as well.
Anyway - let us know if you find out what is wrong with that charge / Power ON LED there??
Best regards,
Frank