power wise charger blowing the 50 amp fuse

[remac]

Please don't use the cart to test the cable for a short.
An ohmmeter is cheaper and safer.

[jetfan1950]

Yep. All testing is being done with volt meter. It would be nice if they had a 50 amp breaker instead of the $8 fuse that keeps blowing.

[jetfan1950]

Checked across the connector plug and jiggled the wires everywhere and no short. Rechecked the diodes using diode position on the dvm. Infinite in one direction, 527 in the other direction. Same for both diodes. Without plugged into AC and plugged into the cart we quickly touched the black wire to the ammeter and drew big spark. It would have popped the new fuse. His model is 28115 g04. The style with only one ckt board. Mine has the two ckt boards. We opened mine to compare and all seems the same except the black wire from the cart on his goes to the ammeter while the white wire on mine goes to the ammeter. Probably doesn't matter. We are at a loss as to what to try. Took some voltage readings and the difference between his and mine is that we measure 36.4 volts across the white wire from the cart and the ammeter mounting plate. We do not get any voltage reading on mine across that mounting plate. We get the voltage reading across the ammeter stud but not the mounting plate. Perhaps the ammeter is shorted to the chassis. We are going to try removing the ammeter to see what happens. Be right back.

[jetfan1950]

Same readings with ammeter out of the ckt. Disconnected the diode plate from the support frame and now getting no voltage across the support bracket. Mike is pretty sure the old diode setup had no insulation between it and the frame. His set has 2 diodes mounted on a 3 inch strip which is bolted to the support frame. Mine has 2 individual diodes each mounted to the support frame but they are definitely insulated from the support bracket. I'll attach some pictures. My setup is the middle picture.

[jetfan1950]

For some reason today I do not have the option to edit my post. Post 41 has a typo. We are measuring 37.4 volts across the plate not 36.4.

Oddly, I have the edit option for this post but none of the previous posts. Prior to this post, I had no edit option for any of the posts.

[JohnnieB]

Originally Posted by jetfan1950

Checked across the connector plug and jiggled the wires everywhere and no short. Rechecked the diodes using diode position on the dvm. Infinite in one direction, 527 in the other direction. Same for both diodes. Without plugged into AC and plugged into the cart we quickly touched the black wire to the ammeter and drew big spark. It would have popped the new fuse. His model is 28115 g04. The style with only one ckt board. Mine has the two ckt boards. We opened mine to compare and all seems the same except the black wire from the cart on his goes to the ammeter while the white wire on mine goes to the ammeter. Probably doesn't matter. We are at a loss as to what to try. Took some voltage readings and the difference between his and mine is that we measure 36.4 volts across the white wire from the cart and the ammeter mounting plate. We do not get any voltage reading on mine across that mounting plate. We get the voltage reading across the ammeter stud but not the mounting plate. Perhaps the ammeter is shorted to the chassis. We are going to try removing the ammeter to see what happens. Be right back.

IT does matter. This might be the problem.

In DC control wiring, the Black wire is the identified conductor and it is NEGATIVE.
Technically, a wire with positive DC voltage on it is supposed to be any color other than black, but it gets a little murky with wire gauges heavier than about 8 Ga and not all manufacturers follow the color code since it is not a law.

In the charger, the center tap of the transformer is negative so that is where the black wire ought to connect.

The heatsink is positive, so that is where the non-black (white in this case) wire attaches, via the ammeter and fuse.
Please note that the wire attached to the ammeter on the schematic I posted, is white.

Originally Posted by jetfan1950

Same readings with ammeter out of the ckt. Disconnected the diode plate from the support frame and now getting no voltage across the support bracket. Mike is pretty sure the old diode setup had no insulation between it and the frame. His set has 2 diodes mounted on a 3 inch strip which is bolted to the support frame. Mine has 2 individual diodes each mounted to the support frame but they are definitely insulated from the support bracket. I'll attach some pictures. My setup is the middle picture.

I suspect what you are calling a support bracket is actually the heatsink the diodes or the diode assemble is mounted on. It is a "live" piece of metal and is isolated from the charger chassis by the nylon standoffs seen in the photos you've posted. It is the source of the positive voltage output from the charger.

The diodes whether individually bolted heatsink, or mounted on a holder that is bolted to the heatsink, are (or should be) electrically connected to the heatsink.

------------
Sounds like someone has been moving wires around inside the charger, so I'd trace the negative battery pack terminal in the cart back to the center tap of the transformer and the battery pack's positive terminal back to the heatsink in the charger.

[jetfan1950]

Sorry for the long delay. We swapped the black and white wires and no sparks. Fuse does not blow but we are not getting a charge - no movement of the ammeter. No hum when plugged into the wall. We jumped the switch/circuit board and we then hear the hum but still no reaction of the ammeter. In case the ammeter may be defective, we checked the pack voltage while the switch was jumped but the voltage did not show any increase. We then plugged in our good powerwise charger and the pack voltage began to show an immediate increase so we are pretty sure the defective charger is not putting out any current. What can we check at this point?

[radioman]

Originally Posted by jetfan1950

Sorry for the long delay. We swapped the black and white wires and no sparks. Fuse does not blow but we are not getting a charge - no movement of the ammeter. No hum when plugged into the wall. We jumped the switch/circuit board and we then hear the hum but still no reaction of the ammeter. In case the ammeter may be defective, we checked the pack voltage while the switch was jumped but the voltage did not show any increase. We then plugged in our good powerwise charger and the pack voltage began to show an immediate increase so we are pretty sure the defective charger is not putting out any current. What can we check at this point?

I would check the diodes again since they have been subjected to that reverse current surge current blowing the 50 amp fuse in the charger and make some voltage measurements while you have jumper in place.

[jetfan1950]

Diodes checked out OK. While taking measurements, I found one of the wires to the capacitor had broken off. Unit is now charging the pack with the ckt board bypassed and the ammeter not showing any reading. (Pack voltage showed 45.3 volts while charging). Disconnected the charger until I check past postings for the impact of charging with the ckt board bypassed. Don't want to burn up something else. Thanks to everyone for their help.

[radioman]

It will eventually overcharge your batteries without the circuit board to detect the full charge battery pack voltage.

When you remove the jumper from the control does the charger still not work when you plug it in to cart? If not it may have been damaged by reverse current too. The wire broken on the capacitor would keep charger from developing charging current but not turning on when plugged into cart. Charging current also has to go through the amp meter. It too was probably damaged with the reverse current if it is not indicating. JohnnieB did good finding reversed output wiring error. You got it working good enough you should be to finish fixing it.