sboxer

My Feedback: (1)

I have a 19.2 volt nicad home-made battery pack that I use for my engine starter (i'm starting a ryobi 33cc so I need the extra umph). I got the idea of using a 19.2 volt battery charger for power tools as it's !QUOT!charging base station!QUOT!. I purchased a used sears charger on e-bay and am now wondering if this is possible. The bottom of the case says that the charger puts out 22 volts, but my multi-meter indicates that it is sending out 33 volts. I know that batteries this unit charges are nicads. So these are the questions:

1)Am I on the right track? In other words, am I going to explode a battery pack by doing this.
2)Anyone know how to trick the unit into starting the charging cycle when the correct battery is not inserted. There is a 3rd clip in the charging bay that seems to put out a few volts. Maybe that is the key.
3)Whats the story with the difference in volts. Is it an issue of just not having a load on the charger?

Thanks!

JimTrainor

The output current is most likely regulated (it's a fast charger, right?). If so, then you defineltly need to load it in order to draw any conclusions.

sboxer

My Feedback: (1)

It is a fast charger. I guess I should put a load on it and test what kind of power is flowing out during a charge.

sboxer

My Feedback: (1)

Well-I think I am stuck. Regardless of how much of a charge is on the starter batteries, the sears charger always indicates fully charged. I think that places it in a trickle mode-which would be good, but I'd like to know how to kick in the fast charger cycle. I don't see any mechanical levers that tell the charger that a batter has been inserted. My guess is the 3rd contact that when shorted with the + or - contact kicks out 8 or 9 volts. Any thoughts battery gurus?

SB

KB9STD

My Feedback: (1)

OK, I am not an "Expert", And I'm not familiar with your particular charger! But I have a similar "Ryobi" charger,That I have used to charge several different batteries. The third connection (at least on my charger) is used for a thermal switch whithin the battery pack. It connects to either the + or - (I don't remember which right now) through the switch,and stops the fast charge if the battery is hot.Try connecting the third leg to the Plus,and then connecting the battery.If that doesn't work,connect it to the minus and then connect the battery.
Do this ONLY if you are willing to risk damaging the charger. As I stated "I don't really know what I'm talking about"! Please be ready to unplug everything in a hurry,if something goes unexpectedly,and DON"T leave it unattended for at least the first few charges.
I hope this helps! Good Luck!!

sboxer

My Feedback: (1)

Thanks for the help. I bet it is close enough to the same unit. Are you suggesting that I use the 3rd post to the + on my battery or on the charger (it probably does not matter).
It seems to work fine as a slow charger (which is worth the $ I paid for it).
SB

KB9STD

My Feedback: (1)

sboxer , sorry to take so long to get bak.I have been working LONG hours and just saw your rely. I use small "test Leads" with ligator clips myself.I use one for the positive lead,another for the negative, and a third from the 3rd terminal to the + terminal on the charger. I expect the battery will go into a fast charge,Peak and then continue in trickle mode.Sure hope this helps. Please let us know how things work out.