DPI charger

[branson]

so according to Johnny B it's possible to change a 42 volt charger to a 48 volt charger by changing the board. how different is this charger from a standard charger. can I get a dpi bored and put it in my standard charger. I've been thinking about putting a light dimmer switch on the line side of the transformer (bypassing the control board of course) to limit the output voltage and then I can leave it on as a float charger. I have a power wise 36 volt.

[JohnnieB]

Originally Posted by branson

1. so according to Johnny B it's possible to change a 42 volt charger to a 48 volt charger by changing the board.
2. how different is this charger from a standard charger.
3. can I get a dpi bored and put it in my standard charger.
4. I've been thinking about putting a light dimmer switch on the line side of the transformer (bypassing the control board of course) to limit the output voltage and then I can leave it on as a float charger.
5. I have a power wise 36 volt.

1. That is my understanding based on talking to people at DPI.

2. Very different. They both both have the same AC power plug and the same DC output plug, but everything between those two plugs is different technology.

3. The secondary voltage of the step-down transformer DPI uses in their 36V charger isn't high enough to power the 42V PCB assembly they use in their 42V charger, so I doubt if the ferroresonant transformer from a 36V Powerwise charger would either. Entirely different transformer designs.

4. You might be able to create a trickle charger this way, but not a float charger. A trickle charger is essentially a battery charger with a low output current and no provisions to limit the batteries On-Charge voltage other than the fact the current is low.

A float charger limits the battery's On-Charge voltage to about 2.20 Volts per cell, so the don't gas excessively or overcharge when left on float for extended periods of time. Basically, the output current of a float charger automatically matches the battery's self-discharge rate plus the parasitic discharge rate, if one exists.

5. Attached are block diagrams for a PW charger and a DPI charger.

[branson]

thanks I figured you would know. its funny I thought the power wise charger would look as simple as the dpi charger does in a schematic and I thought the DPI would be much more complicated schematicm

[JohnnieB]

Looks are deceiving.
It is a schematic for the Powerwise and a block diagram for the DPI.

The PW is a ferroresonant transformer design and the actual battery charger consists of a special transformer and matching capacitor, plus a couple diodes. The control board simply energizes or de-energizes the relay that supplies AC power to the transformer's primary.

The charge profile for the ferroresonant transformer is based on the recommended charge curve for Trojan batteries, but not all battery manufacturers have the same charge parameters, so if you are using something other than Trojan batteries, verify that the Trojan charge curve will charge them properly. (IE: US Battery uses a higher finish voltage, so these old chargers tend to under charge them and reduce their lifespan.)

The DPI charger uses a microprocessor controlled SCR type charger that is located in its entirety on the PCB assembly. The transformer that feed the PCB is and ordinary Step-down transformer.

The DPI has four user selectable charge profiles, so it can be used with most brands of batteries.

[branson]

I did not realize the transformer in a Power wise was special. I figured it was just a step down transformer. you sure are a wealth of knowledge on these things.

[JohnnieB]

With just a transformer, a capacitor and a couple of diodes, some engineers managed to follow the attached charge curve.

Most of the old cart chargers used the same design, but tweaked it just enough to avoid patent infringements, so various value capacitors are used.

They are built like a tank and are 100% repairable. However, a replacement transformer cost as much, or more than, many more modern chargers.

[simple man]

I may be wrong, but I'm pretty sure you cannot use a light dimmer on an inductive device like a transformer. A variable frequency drive may work, but will be expensive!

[JohnnieB]

Originally Posted by simple man

I may be wrong, but I'm pretty sure you cannot use a light dimmer on an inductive device like a transformer. A variable frequency drive may work, but will be expensive!

You are doing it every time you push the pedal in you cart.

An electric motor is an inductive device and the output from the controller is PWM whose duty cycle varies as the pedal is pushed.

A light dimmer varies the duty cycle of AC, but it is still a form of PWM.

However, you are right about a light dimmer not working too well with a ferroresonant transformer, which attempts to maintain a constant secondary voltage as the input voltage to the primary varies. Of course, if the capacitor was disconnected, it would more or less be an ordinary transformer and the output voltage would vary with the input voltage.

[branson]

I was thinking about a dinner because it works on a ordinary step down transformer for low voltage lighting. dimm the transformer the lights will follow. now that I know its not a standard transformer it doesn't seem l like it will work

[simple man]

Originally Posted by JohnnieB

You are doing it every time you push the pedal in you cart.

An electric motor is an inductive device and the output from the controller is PWM whose duty cycle varies as the pedal is pushed.

A light dimmer varies the duty cycle of AC, but it is still a form of PWM.

However, you are right about a light dimmer not working too well with a ferroresonant transformer, which attempts to maintain a constant secondary voltage as the input voltage to the primary varies. Of course, if the capacitor was disconnected, it would more or less be an ordinary transformer and the output voltage would vary with the input voltage.

My capacitors should be in pretty soon, so I'll also try having no capacitor in the tests I'm going to do. I'll post these results in my "Lestronic II" thread.