heat sink/diodes failing on lester 11985??

[stoker]

48V 25amp output..charger has some output,but only charges brand new pack to 52V..
I discharged pack to 47V and amp meter on charger is only showing 4-5A,when I know it should be almost pegged on first startup.Its a onboard (no DC cord) setup on a 1997 taylor dunn. thoughts?thanks

[Fairtax4me]

Is that a Lestronic II? Low output on the older chargers is usually due to a failing capacitor. The size of the capacitor matters very much and has to be correct size for the design of the transformer.

You can try running through the troubleshooting procedures in the manual here: https://lesterelectrical.com/wp-cont...ing-Guide-.pdf

Most parts for these are still available through Lester.

[stoker]

Originally Posted by Fairtax4me

Is that a Lestronic II? Low output on the older chargers is usually due to a failing capacitor. The size of the capacitor matters very much and has to be correct size for the design of the transformer.

You can try running through the troubleshooting procedures in the manual here: https://lesterelectrical.com/wp-cont...ing-Guide-.pdf

Most parts for these are still available through Lester.

thank you type 48LC25-8ET.It does have the jumbo size Cap inside enclosure with transformer and heat sink/diodes.It has separate smaller encloser for the amp meter gauge and relay with electronic board integrated circuit chips (this is mounted directly under seat)

[stoker]

when I measure the 6MF 660V cap,i only get 1.30 MF

[Fairtax4me]

I'd say that probably needs to b replaced. Wouldn't hurt to test the diodes if you have the box open. You do need to disconnect the wires from those before testing. They should all read the same with a diode tester.

Typically if a diode goes bad you'll have a very high input current which will trip the breaker on the charger, or will cause the ammeter to wobble (as the diode is no longer filtering the AC wave output from the transformer). It can cause low charger output if the diode fails open, but there will usually be other symptoms as well.

[stoker]

Originally Posted by Fairtax4me

I'd say that probably needs to b replaced. Wouldn't hurt to test the diodes if you have the box open. You do need to disconnect the wires from those before testing. They should all read the same with a diode tester.

Typically if a diode goes bad you'll have a very high input current which will trip the breaker on the charger, or will cause the ammeter to wobble (as the diode is no longer filtering the AC wave output from the transformer). It can cause low charger output if the diode fails open, but there will usually be other symptoms as well.

when I test diodes with Fluke87 I get .542V and .548V and open circuit with leads switched,so I think I am good there?

[Fairtax4me]

Yeah those seem good to me.
Does that charger have the Horseshoe shaped fuse in the round globe holder? Check and make sure both legs of that are good. If either side is burned out or cracked it should be replaced. If that checks good then I think you should be fine to just replace that cap and you should be back up and running.

Something else to check though is make sure the positive and negative leads from the charger to the battery pack are in good shape at the ends. No corrosion, and the crimps are tight at the ends. And it's also always good to make sure all of the battery terminals are clean and the cable ends have no corrosion and are tight to the post.

[stoker]

Originally Posted by Fairtax4me

Yeah those seem good to me.
Does that charger have the Horseshoe shaped fuse in the round globe holder? Check and make sure both legs of that are good. If either side is burned out or cracked it should be replaced. If that checks good then I think you should be fine to just replace that cap and you should be back up and running.

Something else to check though is make sure the positive and negative leads from the charger to the battery pack are in good shape at the ends. No corrosion, and the crimps are tight at the ends. And it's also always good to make sure all of the battery terminals are clean and the cable ends have no corrosion and are tight to the post.

thanks amigo,The new cap did the trick,pulling 23 amps at startup now versus 4A before fix

[Fairtax4me]

Good deal, glad you're back up and running!