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Unread 05-23-2009, 03:17 PM   #21
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Default Re: How does 48V 2001 Club Cart OBC function?

I have an old one I will send him, if he ask nice.
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Unread 05-24-2009, 03:50 AM   #22
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Default Re: How does 48V 2001 Club Cart OBC function?

Quote:
Originally Posted by Fishing Dude View Post
I have an old one I will send him, if he ask nice.
Hey there Fishing Dude:

I would love to get it and will be happy to reimburse you for the cost of postage. I sent you a PM with the details.
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Unread 05-24-2009, 04:55 AM   #23
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Default Re: How does 48V 2001 Club Cart OBC function?

For those who have asked about what is motivating my interest in the OBC, it is simply curiosity. I have always been keen on understanding how things work and this dang black box at the heart of the Club Car's electrical system is intriguing. After reading hundreds of threads that touched on the CC OBC, I realized that while there was a lot of conjuncture about what it did, no where could I find the hard information from someone who would truly know (probably a CC employee) or could quote a published source that does know - e.g. a CC manual, tech support note, troubleshooting guide, etc.

So I figured I would kind of make it my mission to make that contribution to these forums - because I really believe people with that specific knowledge exists on these forums and have just not fond this thread or contributed to it.

Let me hasten to add, that I hope that those that have responded to this thread so far will not take offense as none is intended. On the contrary, I am very grateful and you have certainly helped bring together a lot of the information that does exist into one place.

Think about if we knew as little about the functions of an automobile engine as we do about the functions of the OBC. That would certainly make it much more difficult to diagnose what was wrong with a car.

As part of this investigation, I have recorded the charging current and pack voltage as often as once per second for over a dozen charge cycles on my cart and for up to 16 hours long. I have seen some interesting "short term (2 to 240 second) events" during the charging. These events were almost certainly orchestrated by the OBC.

In order to interpret the graphs (and events) correctly, it it is almost essential to know what the OBC is trying to do. Otherwise, we could make some guesses - which I believe would only add to the body of information about the OBC that ranges from very likely true to probably half-truths to likely erroneous.

I will post the more interesting of this charging cycle data when I figure out how to either get a high quality .jpg file in the thread (about 150 KB in size). Otherwise, I could probably find a place to host the pictures (mostly of plots) and link to them if that is allowed.

Cheers...
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Unread 05-26-2009, 12:57 PM   #24
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Default Re: How does 48V 2001 Club Cart OBC function?

OK. Some progress.

Fishing Dude has graciously sent me his old OBC and I intend to disassemble it this weekend.

This will be a destructive disassembly just to see what is inside, not to repair it.

Does anyone have any experience on possible ways to accomplish this?

Thanks.
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Unread 07-05-2009, 11:57 AM   #25
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Default Re: How does 48V 2001 Club Cart OBC function?

I have a bit more information, from the service manuals and other reading.

/*
1. The OBC is only used to control the charging of the batteries.
*/

It is essentially a battery (charger) control computer. It controls the charger, does the lockout function so you can't drive the vehicle with a charger connected, and keeps track of energy use and battery cycles.

/*
2. The #6 gauge wire from the Battery pack's negative post (B-) passes THROUGH the OBC to the Controller B- post without making electrical contact. Perhaps there is a heavy duty current sensor in the OBC that it passes through - like a "Clamp-on" DC amp meter?
*/

It's exactly a DC Current clamp-on ammeter (without, of course, the clamp-on function), that keeps track of amp-hours drawn from the battery when operating, and (usually) shuts the charger off after 110%(?) of that energy has been returned to the batteries.

/*
3. If #2 above is true, this implies that the OBC is measuring (but not necessarily controlling) some hefty operating current, not just the charging current.
*/

Right, all current in and out of the batteries flows through the negative battery wire, which is measured by the computer.

/*
4. The OBC controls the operation of the Yellow Warning Light (brown wire)
*/

Yes, when something goes wrong with the batteries or their charge regimen, the yellow warning light will come on. Also note that the YWL has an infrared emitter in it to communicate OBC findings to the Club Car Communications Display Module (see below).

/*
5. The OBC monitors the Battery Pack voltage (red & black wires)
*/

It needs to know the battery voltage, as a secondary battery health indicator.

/*
6. The OBC controls the operation of the Forward-Reverse Solenoid (yellow wire). This looks like a operation vs a charging function to me.
*/

This appears to be the "Operation" solenoid, forward/reverse is by the big switch behind/beside the operator's knees. At least on my 2001 vehicles... This is where it performs the lockout function.

/*
8. The OBC apparently controls whether the charger feeds charging power to the cart by controlling the voltage on the third pin (grey wire) of the charging receptacle. This does not vary the charging current or voltage - it is a "on or off" control.
*/

That's correct, it enables or disables the charger. Note that while this _does_ allow the marketing department to call the charger a "Computer Controlled Charger", it's the computer in the cart that's controlling the charger. The OBC will also wake up every 2 weeks and charge the batteries during long-term storage.

/*
9. The OBC is made my Lester for Club cart as a proprietary part. I could not find any information on it at the Lester site. There are several part numbers for the Club Car OBC, but I suspect they will all be very similar.
*/

There seem to be a number of different part numbers (101909901, 101909902, 101909903, etc), they seem to be specific to various models of carts, and may have programming (or even wire harness length) differences between the different models. I'm not sure I'd swap models around without a good understanding of what the differences are... Note that the {Firmware? Hardware?} Version number may also be significant.

Some more info and additional thoughts:

The CDM gets the following information from the OBC:

Battery Voltage
Energy Units(*) removed since last charge cycle
Total Energy Units removed since vehicle was new
Last Charge Termination Type

(*)EU appears to be "KillowattHours", as near as I can tell.

Total Energy Units tells you about the lifetime of the batteries. Since Trojan batteries are warrantied in EU, you can determine warranty status by use of this number.

Last Charge Termination Type is one of:

1=Incomplete (you unplugged the charger or the power failed before charge was complete).
2=DVDT termination. Voltage rise can be used as an indication that charge is complete, but this should only happen with new batteries or controller is reset.
4=Normal charge cycle
8=Timeout. Charger ran for 16 hours, and computer shut down charger.

[Looks like the CDM is only $120-ish, might be worth having to determine what yours carts are doing...]

Did you open up the OBC that FishingDude sent you?

I've got a cart that doesn't seem to want to stop charging, so I'm probably in the market for a new computer...
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Unread 07-09-2009, 02:44 AM   #26
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Default Re: How does 48V 2001 Club Cart OBC function?

Wow! Thanks for the great post wpns.

Although I have not posted to this thread for 6 weeks - it was starting to look like a monologue - that does not mean I stopped doing my research. Like you, I eventually located the service manuals and everything you stated is correct. In fact, I have accumulated so much information and data on my own 2001 DS (non-IQ), that it has filled a 1" notebook plus 500 files and 1.6GB of data on my computer. My problem is how to disclose it, since a lot is in photographs and detailed plots of pack voltage and current over time, in both the charging and discharge (running) mode.

Yes - I did take apart the OBC that Fishing Dude so kindly donated to the project (a big THANKS FD!) The computer he sent me was from a 1999 Club Car, with a Lester Part #18300 ver 1.33. My 2001 OBC now has a Club Car part number on it, 101909901 in addition to a Lester P/N 21065-01 ver 1.35. I believe there are very few functional differences in them from the description of what they do in the service manuals.

One difference in OBCs is that before 2001, the diagnostic infrared (IR) LED was mounted on the OBC, so was difficult to access. In 2001, they changed the dash panel lamp from red to amber and moved the IR LED to the right side of the amber battery warning lamp assembly. That made it a lot easier to use the CDM to get the readings wpns described. The color change probably was to let the IR pass through the front face better and differentiate that it was a lamp + IR assembly.

Disassembly Procedure:

After drilling out the plastic posts that were holding the potted section to the metal backing and removing the nut that turned out to be holding and heat sinking a Silicon Controlled Rectifier (SCR) (the 2001 OBC does not have this nut but does have a SCR), I pried the potted section from the metal for further work.

First I tried to dissolve the potting material with alcohol, turpentine, acetone and lacquer thinner. No luck at all.

The potted section was easily separated from a plastic containment shell which covered the part of the potting that did not face the metal plate. Then I mounted the potted core in a vise and used a 500/1000 watt heat gun and screwdriver to reasonably carefully chip away the potting material. After about 4 hours of work, I had the printed circuit board (PCB) and most of the parts exposed. The chipping was not difficult other than to try to preserve as much of the circuit as possible, so I could try to determine what it did.

Let me say that if you intend to disassemble it this way with the intent of repair - forget it. You will damage most of the resistors, diodes and other small parts doing so.

What I found was 4" x 5.5" printed circuit board with a true microcomputer powered by a 8-bit Zilog microprocessor, which conveniently has on-board memory for programming and computational purposes. There is also a chip for semi-permanent storage of the energy data collected each time the car is run or charged. In addition there are many other circuits for measuring and recording the charging and running current and voltages vs time, etc. That is the way they get the energy used and replenished as

Energy = Amps x Volts x time

Since amps x volts = watts, if we measure time in hours we get watt-hours. Divide my 1000 and we have kilowatt hours (KWH), a more convenient unit.

I mentioned the SCR earlier. A SCR is a device to control the flow of current (amps). That is the device in used in a lamp dimmer. I am quite certain this is used in the OBC primarily to Control how much current (as a function of time) is allowed to flow from the charger when recharging the batteries. This is why there are 3 phases in the battery charge cycle: An initial high charge phase (~15 to ~10 amps), a taper off phase (~10 to a few amps) and very often (on my cart) a conditioning phase, which is almost perfectly maintained at about 2.5 amps by the SCR. I will show you a plot in a later message and also post a few pictures to show you the disassembly process.

For those that read this far, you get a "hang in there" reward - the BIG News, is that Club Car as essentially disclosed a great deal on how their OBC very likely works in patents filed by their employees and those of Lester Electrical. Probably the most descriptive is U.S. Patent 6,087,805 at

http://www.google.com/patents?vid=USPAT6087805

It is no guarantee that everything in the patent is in the 2001 OBC and the OBC may contain things not in the patent - but from what I can determine so far, it is a very close match. Be sure to click on "Read this patent" or "Download PDF" to get the full story.

TBC...
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Unread 07-09-2009, 03:58 AM   #27
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Default Re: How does 48V 2001 Club Cart OBC function?

Here are a few pictures to go with my last post.

1. Separating the OBC parts

2. Using a heat gun to warm the potting material to make it much easier to chip from the circuit board

3. Near the end of removing the potting material

4. The heart of the OBC is a Zilog microprocessor

5. A typical plot of charging current (amps) vs time (hours). This plot may require a bit of explanation.

The charging current was measured indirectly by inserting a "meter shunt" in series with the negative lead to the battery pack, so all current (amps) to the pack had to pass through this shunt. This shunt has a very small resistance (0.000187 ohm) so was negligible to the operation or charging of the cart, e.g. it is much less than the resistance of even a single battery cable. It was designed when 214 Amps of current flowed through it, it there would be a voltage drop of 40 mV (millivolts or thousandths of a volt) recorded. This is easily measured by a good voltmeter which fed the data to a laptop computer each second. The laptop program made the plot.

The vertical axis of the plot is measuring the number of mV across the shunt and runs from 0 to 2.8 mV which corresponds to 0 to 15 amps (in red pen).

The horizontal axis is actual time (printed) or hours into the charge in red, 0 to 4 hours.

This battery recharge was made after driving an average of about 18 mph for 8.6 miles, so the pack was probably only 25% or so discharged, hence the recharge time was relatively short.

Phase 1 is a relatively high charging rata starting at 15 amps and going to 11 amps after 2.1 hours into the charge cycle.

Phase 2 starts at 2.1 hours and lasts to 3.2 hours when the current has dropped to 3 amps.

Phase 3 is the conditioning phase where the current was maintained constant at 3 amps until 3.9 hours, when the charger automatically cut off, probably having replaced 110% of the energy it measured on the way out.

The battery pack voltage was 59.9 volts at this point - which is NOT high for the end of a charge, but that is another story...

In addition to a 2 second break about 10 seconds into the charge (not shown on this plot which started right after that), there are 2 points at 1 and 2 hours into the charge (almost exactly) where the OBC shuts off the charger for a couple of seconds, so the amps naturally dropped to zero. This would not be noticed if you did not have your eye on the charger at that precise time or were recording it each second. These extremely regular breaks are certainly controlled by the OBC and were the first thing that made me suspect that the OBC was a "digital computer" and not a collection of analog parts. So I just had to take one apart...

I believe that Phase 1 is the natural fall off in charging current as the pack voltage increases, so the difference between that and what the charger would put out decreases - so less charging current (amps). Notice it is a bit "bumpy".

I think Phase 2, which is quite smooth, is controlled by the SCR in the OBC as it continues to record the amount of energy put back into the batteries, shooting for 110% of what was removed since the last charge while tapering off the current to keep the battery cooler.

In Phase 3, I believe the OBC's SCR is holding the current low and constant while it "conditions" the batteries. The conditioning causes the batteries to bubble so that the battery acid will be redistributed uniformly from top to bottom in each cell. According so some non-Club documentation, this should not be necessary to do every cycle, but it has occurred on each of the 40 or so cycles I have measured on my cart.

During Phase 3, the battery pack voltage can go quite high, e.g. to 63 volts or slightly more. The OBC may have a sensor that stops the battery charge when the voltage gets too high.

TBC...
Attached Images
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File Type: jpg IMG_1505 (Medium).jpg (77.9 KB, 103 views)
File Type: jpg 12I Bob's CC after new Solenoid & OBC. 8.6 Mi Semi-Aggressive Run to Walmart (Large).jpg (38.7 KB, 77 views)
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Unread 07-09-2009, 07:16 AM   #28
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Default Re: How does 48V 2001 Club Cart OBC function?



That is a tremendous amount of information. Thank you, I somehow have a better understanding of what the OBC does.
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Unread 07-09-2009, 07:43 AM   #29
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Default Re: How does 48V 2001 Club Cart OBC function?

Ty for all the info Dr Bob.
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Unread 07-09-2009, 08:00 AM   #30
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Default Re: How does 48V 2001 Club Cart OBC function?

Looks like your dead OBC futhered the scientific cause FD
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