PowerWise PCB schematic available?

[yorlik]

I have searched for hours and not found a schematic for the powerwise 36v charger PCB. My wife dropped it off shelf on floor and now it will not auto shut off when done charging. I can repair it if I have the schematic.

thank you.

PCB ??

do you mean QE ?

[mattadata]

I suspect he means Printed Circuit Board (PCB).

Originally Posted by mattadata

I suspect he means Printed Circuit Board (PCB).

oh ... the timer relay

[yorlik]

Yes, that pcb (Printed Circuit Board).

Anyone have a schematic of it please?

thank you.

i have never seen one i just get the replacement one
are you sure it is the timer bad ?

[yorlik]

no, timer is not bad, pcb is tho....

pcb has many functions, among them:

1) turns on charger when senses plugged into cart - ok
2) turns off if 16 hours is exceeded - not ok
3) SMART circuit that lets charger be called "smart" that turns off when actual charge done -NOT OK

#3 is critical: with it not working, EVERY charge becomes an overcharge or "equalize" charge. It charges to 7.6v or higher rather than shutting down at 7.4v full charge level. pegs voltmeter on cart.

guess i will have to reverse engineer it and make schematic myself... all these years being out there I figured it hard to believe no one has done this yet.

cause it's cheep to replace ... if you do, post it i would like to see it

[JohnnieB]

Electronic technicians and other repairmen have been subliminally preconditioning people to non-repairable throwaway PCBs for decades.

It started with the transition from discreet solid-state components to ICs, making troubleshooting more complex, and progressed greatly when multilayer printed circuit board were introduced, making component replacement exceedingly difficult.

Fortunately, the control boards for Ferroresonant Transformer type chargers tend to be hybrids of discreet components and simplistic ICs mounted on a single layer board.

Unfortunately, there are about a dozen variants, but they all do the same thing, that being applying or removing AC line voltage to the primary of the Ferroresonant Transformer. Basically, they have absolutely nothing to do with charging the battery other than turning the charger ON and OFF.

The electronics on the board are powered by the voltage on the small red and black wires (aka battery sense wires) and when the voltage on those two wire is high enough to energize the relay on the board, AC line power is applied to the transformer.

Since the battery sense wires are directly or indirectly connected to the output from the charger, the relay will stay energized until the circuit feeding its coil is broken.

When the output from the charger (aka On-Charge voltage of the battery pack) reaches about 45V +/- 1V (for a 36V charger), which is 7.3V to 7.7V per 6V battery, the relay coil circuit is broken, de-energizing the relay and removing AC line power from the transformer.

In later versions, a backup timer was included in the board circuitry to break the relay coil circuit if the ON-Charge voltage failed to climb into the 44V to 46V range in the allotted time. (Varies from 12 to 16 hours) Earlier versions didn't have an on-board timer and an external mechanical timer was used.

FWIW: If the charger is disconnected from the cart before the charger shuts off automatically, the output voltage instantly attempts to climb to its maximum, shutting off the charger in the process.

To make things more interesting, some of the control board manufactures had a nasty habit of wiping the tops of the ICs they used so they cannot be identified.

Sadly, an reverse engineered schematic of one board won't apply to the other variants of the board.


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BTW: The max recommended On_charge voltage for Trojan batteries is 2.79VPC (Volts per Cell), with is 8.37V for a 6V battery and 50.2V for a 36V pack. (Trojan charge curve attached)

[yorlik]

Thanks for replies guys.

I spent some time on the pcb today and made the schematic for most of the analog portion of it. There is an adjustment pot to adjust the shut off voltage but on mine it does not work properly due the microcontroller that I have no program for....

A couple comments for FWIW....

Obviously JonnhyB you know the only 'control' is that AC power input relay to turn on or off the ferro transformer. It is good for folks trying to diagnose issues to know that the capacitor can change values and change the output constant voltage; I had that once on my GE Electrak charger and it only output 37v max, thus never fully charging the batts.

"Unfortunately, there are about a dozen variants"

I doubt there are a dozen variations of PCBs from the OEM for the powerwise charger; yes, the aftermarket folks have lots of variations; so a schematic of the OEM powerwise will be pretty accurate for the majority of the people who care.

"When the output from the charger (aka On-Charge voltage of the battery pack) reaches about 45V +/- 1V (for a 36V charger), which is 7.3V to 7.7V per 6V battery, the relay coil circuit is broken, de-energizing the relay and removing AC line power from the transformer."

For anyone who cares about long life for their batteries, the actual output voltage to the batts is critical: to have a charger that outputs from 7.3 to 7.7v range would be useless.

"FWIW: If the charger is disconnected from the cart before the charger shuts off automatically, the output voltage instantly attempts to climb to its maximum, shutting off the charger in the process. "

Some may, but not the powerwise by EzGo: it has a sense line that sees if the connector is plugged in or not. It a 3rd wire in the charger output cable. You can see the pin in the connector if you look closely. Nothing to do with actual voltage of the output: this little sense line connects (shorts) to the - side when you plug it into the EzGo receptacle: THAT sends the start/stop signal to the powerwise charger to turn on or off. Nothing to do with actual voltage.

As an aside, if one has an older model cart without the new style connector with the 3rd pin, they can add a simple switch as I did to the powerwise front panel that shorts the two pins for you: then the 'smart' powerwise will turn on and charge the older golf carts too as I do.

"To make things more interesting, some of the control board manufactures had a nasty habit of wiping the tops of the ICs they used so they cannot be identified. "

For reference, EzGo did NOT wipe the IC part nos, at least from the powerwise I have. There are 2 chips inside: 1pc LM324 quad op amp, and 1pc COP8 8bit with 1k on board memory microcontroller with 16 bit built in timer. It is programmed in simple machine language. Without a copy of the program, there is no way to know exactly what they are doing.

But one thing is clear: the analog pot adjusted voltage to shut off level ends in one of the LM324 op amps arranged as a comparator: it sends a 5v on/off sig to one of the microcontroller inputs to tell it time to disconnect on full charge - if before the 16hour timer timeout.

Unfortunately for me, the micro computer seems to have a 1/2 second clock that constantly adds 5v sig to the analog actual battery voltage sense, I believe as a way to not falsely shut off when a certain voltage 42, 43, 44 volt etc) is reached. Averages it out over time.... THEN it turns off the actual AC relay with a simple 2N2555 TO-3 transistor. Mine does not work and will not shut off on voltage sense.

It DOES shut off when the cable is unplugged from the cart of course sinse that is a simple contact input to shut off.

I wish my Trojan batteries would follow the curve shown above: but in my case, if I allow 50.2v into mine overnight, I will be buying 6 new ones the following day: Last buy was nearly $700 and I am not ready to do this again so soon. I have T-105 batts and the Trojan site clearly states for mine to charge to 7.4v (44.4v) or equilize (boil) once every couple months at 7.8v (46.8 v) for a couple hours MAX. So to charge to over 50v would be suicide for them. http://www.trojanbattery.com/tech-su...y-maintenance/ My ferro outputs about 48v no load so I need a voltage sense shut off.

Since I cannot get to the microcontroller program to further diagnose my issue, I will have to buy one of those 15 or so variation PCBs being sold on ebay: DOES ANYONE HAVE A RECOMMENDATION ON THE BEST ONE? I certainly do not want to buy one that has 45v+/-1v output or that will go to 50+volts!

Thank you.