Think I have a charger problem

[kernal]

Just took readings again. Pack voltage is fluctuating at 41.6--41.7 and seems to have stabilized. Each battery is at 6.9-7.0

Charger amps dropped to ~ 16

[yurtle]

Question to JohnnyB,
Is the sensing wire used to determine pack voltage to turn off, or just to turn on?

[JohnnieB]

Originally Posted by yurtle

How would the transformer hum if it's unplugged from AC?

Read the whole sentence.

"Unplug charger from AC power while charger is charging cart."

Perhaps it would have been better to reverse the order of the two phrases.

While charger is charging cart, unplug charger from AC power.

[JohnnieB]

Originally Posted by kernal

Pack resting voltage is 38.0. Plugged in charger. Pack voltage is 41 and rising slowly. Each battery is 6.7--6.9 and rising slowly.

Originally Posted by kernal

Just took readings again. Pack voltage is fluctuating at 41.6--41.7 and seems to have stabilized. Each battery is at 6.9-7.0

Charger amps dropped to ~ 16

Sum of the battery voltages roughly equals pack voltage and none are over ~0.1V lower than the rest and the amp flow is consistent with the On-Charge voltage, so the On-Charge voltage ought to be climbing steadily with ~16A flowing through them.

In all honesty, this one almost has me stumped.
The only thing I can come up with is that not all of the 16A is actually going through the batteries.
Something like a partial short between the + and - wires someplace in the charging loop.

The cart runs normally, so pull the wires from the charge receptacle off the battery pack and measure between them with an ohmmeter. There should be infinite ohms (open circuit) between them.

Do the same check on charger. Disconnect the white wire from the ammeter going to the output cable, or you'll get a reading through the diodes and transformer.

[kernal]

Been charging for about an hour and fifteen minutes now. Pack is holding at 41.9-42.0 and individual batteries are 6.9-7.1. Amps are steading at ~ 15. Since I started with a fully charged pack this seems abnormal to me. This is essentially an equalization charge and I think the amps should be down to the 3-5 range by now.


Ok I'll do those tests shortly

[yurtle]

Originally Posted by JohnnieB

Read the whole sentence.

"Unplug charger from AC power while charger is charging cart."

Perhaps it would have been better to reverse the order of the two phrases.

While charger is charging cart, unplug charger from AC power.

I promise I'm not trying to be a smarta$$ (this time), I just want to learn and understand. It sounds like if it's malfunctioning, it's possible that the transformer will continue to hum, after it's been unplugged. Is that right? I was just wondering if the control boards somehow act like an inverter to cause it to "backfeed" the transformer.

Originally Posted by JohnnieB

2. Turning OFF: Unplug charger from AC power while charger is charging cart.
If charger's transformer stops humming, it is GO.
If it continues to hum, further troubleshooting is needed.

Unfortunately, I sold my PowerWise, so I can't go try this.

[JohnnieB]

Originally Posted by yurtle

Question to JohnnyB,
Is the sensing wire used to determine pack voltage to turn off, or just to turn on?

Both.

All the battery charging stuff (output volts and amps) is determined by the ferroresonant transformer and capacitor.

The AC power to the transformer's primary is connected through a relay that is controlled by the control board, which is powered by the battery sense circuit.

For a 36V charger, the sensed voltage has to be greater than about 28V before the control board will energize the relay.
Once the transformer is powered, its rectified output voltage becomes the sensed voltage, essentially creating a self-holding relay circuit.

When the sensed voltage climbs to a predetermined value (About 45V for a 36V charger), the self holding relay circuit is interrupted and the reply de-energizes, interrupting the off AC power to the transformer.

The control board also has a timer that de-energizes the relay is the sensed voltage does not reach the cut-off voltage in a predetermined amount of time. Typically about 16 hours.

[yurtle]

I was just wondering if the sense wire terminal might be dirty or loose, letting it think the shutoff voltage hadn't been reached, but you're right, that doesn't explain the amps.

[JohnnieB]

Originally Posted by yurtle

I promise I'm not trying to be a smarta$$ (this time), I just want to learn and understand. It sounds like if it's malfunctioning, it's possible that the transformer will continue to hum, after it's been unplugged. Is that right? I was just wondering if the control boards somehow act like an inverter to cause it to "backfeed" the transformer.

Wow! My brain has been in Outer Mongolia this morning.

The correct second test is to unplug from the cart, rather than unplugging from AC power.

I went back and corrected the statement.

Thank you for catching my error.

----------
What happens is that the charger's output voltage climbs to max the moment the current stops flowing to the battery pack, and will exceed the predetermined cut-off voltage, so the control board should de-energize the relay and shut of the charger.

[yurtle]

Did the ammeter go to zero when you were unplugging it? The movement in those meters is pretty sensitive to dust and age, and the chargers are usually in a less than ideal environment, if it gets banged or cracked.