Sulfur, Acid, Boiling, Rotten Eggs, etc.


New Member
Reference “Club Car” posts such as:
cc “charger won't shut-off”
cc “charger not cutting-off”
cc “charger drops down to 5amps and doesn’t cut-off”
cc “charger boiling batteries”
cc “rotten egg smell after long charge”
cc “acid smell”
cc “ sulfur smell and charger doesn’t cut off”

After reading “posts after posts” like those above and after experiencing the same or related “problems” several times, I decided to research and run some tests on my ’02, IQ, CC, Villager-4.

I share this information in hopes that it may at least provide some help to those that have, are, or will experience the same or what may just be similar problems. I am not an expert on the IQ on-board-computer (OBC) or the chargers that are made to work with them. I have, however, collected articles, notes, visited and discussed with local CC dealer (not saying dealer was an expert by any means), and I tested my theories. Don’t take all of what I am including here as the “gospel”, but rather as thought provoking information. Perhaps this will lead to posts from real experts (not the Jeremy Mayfield type) or posts including “certified” documentation from CC or from a CC IQ OBC manufacturer. Next time I do something like this I will try harder to get certified documentation. You may remember that I didn’t have the correct wiring documentation when I did my re-wiring. I had the wiring diagram for the 2002 IQ DS 48Vdc System. I didn’t find-out that the Villager-4 was wired like a 2002 Transporter-4 (MCOR) until after I went through hell having to visually and electrically trace all the wiring.

To save writing, re-writing and multiple explanations, here are some basic truths (mine anyway) to remember while reading the remainder of this post (if you choose to do so):
1. Over-charging is not always a bad thing!
2. Continually under-charging is a bad thing!
3. Shallow discharges will result in a longer battery life!
4. Discharges of 50% (or less) are recommended!
5. 80% discharge is the maximum safe discharge.
6. Do not fully discharge lead-acid type batteries (80% or more). This will damage or kill the battery.
7. Do not leave batteries deeply discharged for any length of time.
8. Lead-acid batteries do not develop a memory and need not be fully discharged before recharging.
9. Batteries should be charged after each period of use.
10. Batteries that charge up but cannot support a load are most likely bad.
11. Trojan Deep Cycle Lead-acid batteries (ex.), with NO load, discharge around 4%/week (more if left connected in cart with typical cc electrical system and more if stored above 80 degrees F).
12. Always keep lead-acid batteries at proper level by adding distilled water (when 100% charged).
13. Never add acid or other chemicals to the batteries.
14. Lead-acid batteries can freeze at 20 degrees F if at low charge.
15. Lead acid batteries will not freeze at -40 degrees F if at 75% (or greater) charge.
Here come some “eyebrow risers” (why later).
16. For cc IQ you should use charger which is designed to be used with cc IQ OBC.
17. While charging with the IQ compatible charger, the Tow-Run should be on Run position.
18. The Tow-Run switch should be in the Tow position when cart is being towed, pushed, during long term storage (unless battery charging system is left on [which really is not a good idea either]), for short times as security, or when doing any work on electrical system including, but not limited to, battery disconnect or battery connect. Avoid all possibilities of spark which could damage the OBC.
Here come a couple of important “gotchas”.
19. When changing 48Vdc wiring make sure that the black (-) lead from the # 6 battery runs through the hole in the OBC. The OBC will not operate without it which, in-turn, means the motor won’t either.
20. Note that on stock cc IQ cart, the accessories operate off a 16Vdc to 12Vdc reducer (encapsulated wire round dropping resistor) which is connected in series between the negative (-) 48Vdc terminal strip located behind the OBC (electrically located to the [-] cable after it passes through the OBC) and the accessories which then connect to the (+) positive terminal of battery #2 (+) 16Vdc. When replacing this 16Vdc series connected reducer with a 48Vdc to 12Vdc parallel connected converter which provides 15 to 25 amps (vs. perhaps 8 amps from the reducer) the (-) 48Vdc input must be connected to the negative lead terminal behind the OBC (same point replaced reducer was connected). The (+) 48Vdc converter input is then connected to the (+) terminal of battery #1. The 12Vdc output is then connected to the accessories/switches via dedicated positive and negative wires (NOT using any chassis connection).

Okay, you will see where and how all this OBC/Charger stuff is going in just a bit, but first we need to understand battery "Equalization" what is it, why it is important and in general terms, how it is accomplished (more on how it is accomplished specifically with the cc IQ later). "Equalization" is a term given to describe the process of occasionally over charging the batteries. As noted prior, over charging is not always a bad thing it just means to put in more energy than the batteries can hold. One purpose of "equalization" (from which the name is derived) is to cause all the individual cells/batteries in the series string to become equally charged. However it serves other functions as well. A second function is to do a very complete charge of all the batteries. When the battery string is charged enough for the charging system to sense that the batteries are “charged”, the battery usually is not yet 100% charged, although it is generally over 90% charged. If some of the battery reaction products remain in an uncharged state too long a period they undergo changes that make it very difficult to reconvert them back to their "charged" state, thus making the battery progressively more difficult to fully charge. This is referred to as "sulfating" of the battery, which causes eventual loss of capacity. Another purpose of equalization is to mix up the electrolyte in the battery, which happens because of the gas bubbles that are produced when overcharging. Yes, those gas bubbles smell like sulfur, acid, but best described as “rotten” eggs! Duh!

Trojan recommends 62+ volts for up to 4 hours to equalize a 48Vdc battery string. Others, more or less. In some circumstance 4 hours may not be enough time. A couple of those are when you add new batteries (all would not normally be at same level of charge). Another is when a golf cart only uses a couple of their batteries for accessories as my stock 02 cc IQ. The two batteries used for the 16Vdc to 12Vdc voltage reducer always discharge more than the other 4.

As many of you know, Club Car decided years ago that the best way to control battery charging (as well as for other reasons that will be mentioned later) was to put the “smarts” of the charging circuitry into the golf cart by adding the OBC, while other manufactures decided to use “smart” chargers leaving the cart’s charging circuitry pretty much the same as it had been. Both methods had basically the same capabilities, except that CC went a little further at the time with their OBC providing more diagnostics and having the capability of controlling functions and collecting and showing diagnostic data as well as operational data simply by plugging the IQDM hand-held diagnostic tool into the system. Except for the charging system I understand other manufactures now have similar features.(?)

Okay back to the real purpose of this post for now.
When I first experienced what I called a problem with the cart’s charger not cutting-off and scared of the overcharging due to the rotten egg smell, my mind went back to around 1973 when I experienced the same smell in my car that ended-up with a battery exploding while driving in downtown D.C. Not a pretty site. Apparently the voltage regulator wasn’t working and who knows what else. Anyway, the first time I had noticed it with the cart was when I replaced all the batteries last fall. It was only 4 or 5 charges before I removed the batteries to do my re-wiring and stereo install project and I hadn’t figured-out what I thought to be a major problem at that time. I started trying to figure-out the charging problem during the final work on the total re-wire project since I was connecting and disconnecting the batteries and other wires.

Well, “charger not cutting-off” was not really true in my case. I never gave it the chance. Once the cart was fully charged and the batteries started smelling like “rotten eggs” I cut-off the charger. A couple of times I let it smell for 3 or 4 hours but still got scared and cut it off. One night I forgot about the charger and left it on all night. The next morning the charger was off, the battery voltage indicated fully charged and all appeared okay. I’m going to skip all the details of what I tried during the investigative process for two reasons. One is that you would laugh at me for what all I did do and second it would take too long (as if this hasn’t already).

Through all the disconnecting of the batteries (which I would leave disconnected over night and sometimes for a couple of days) I realized that the OBC would “pass-out” or “go to sleep”. When that occurred the OBC would loose it’s memory and require a kick start with the charger. Then I found that even with the batteries connected but with the Tow-Run switch in the Tow position it would go to sleep. That didn’t happen before all my re-wiring! Then through a lot of research and heavy thinking I realized that I had disconnected the old voltage reducer and had connected the new voltage converter directly to the battery terminals per the instruction sheet that came with the converter. So, since it was not connected “beyond” the OBC as referenced above, I realized that there was no current at all flowing through the negative wire running through the OBC when the Tow-Run switch was set to Tow. I re-wired the converter negative input connection and “son of a gun”, no more falling asleep. I had installed a combo switch/breaker in the input line of the convertor but soon realized only to turn it off when the Tow-Run was in the Run position. (now it stays “on” unless I am removing the battery connections.

Now for the “good stuff”. The cc OBC controls the charging. It knows how long it’s been since charged and % of charged, how long since “equalization”, average charge %s, average charge time, etc., etc. and etc. As long as it does not go sound to sleep for several hours it keeps all that information + more in memory. Guess what! When the OBC goes to sleep and looses the memories, it re-boots and has no records. It then starts over and wouldn’t you know that it sees no equalizations have taken place so it calls for one that lasts quite a while. It communicates with the charger at the beginning and during the charging process. Once it completes the normal charge, it disconnects a regulator that turns the charger on a charge voltage of 62+ volts and begins “equalization”. At 62+ volts a fully charged 48Vdc string will pull about 5 amps for duration of the equalization.

Since I got the wiring straight and since I stopped the OBC from falling asleep, it charges normally for 3 or 4 weeks then it calls for a “equalization”. I no longer get scared and turn-off the charger during the equalization!

I hope all this rambling at least gave some insight into possible “problems” that may not really be problems.

Anyone have an IQDM that you would like to sell cheap?

(Possibly more on OBC features and the IQDM hand-held diagnostic tool in a future post)


New Member
Hey Low and Slow!

Very nice summary of posts and I am sure, many of your own observations and conclusions as well.

I have been doing an extensive 2 month investigation of the Club Car OBC, specifically the one used on the 2001 DS (non-IQ) model, so we are close to parallel. In the IQ model that you are specifically addressing, the OBC interfaces to the controller, so can perform some additional functions, such as maximum speed control. There is also no Run/Tow switch in my cart. Nevertheless, almost all you said was pertinent to the non-IQ OBC as well.

I think you have pretty much hit it on the head with your list of points, so will only add my 2 cents on a few things.

Point 20. You are right that the reducer in the CC is wired in an most unexpected manner. The "ground" of the reducer is about 4 volts higher than the negative terminal of the battery pack. I believe it is more than a series resistor however. If it were that, the voltage reduction would be proportional to the current through the reducer and it would be pretty useless. I have not disassembled it, but I would be surprised if it did not contain components that make it more stable than a resistor - like a zener controlled SCR. It's primary purpose seems to be to allow the use of 12 volt bulbs in the head and tail lights on the cart - which we all have in The Villages Fl, as we can drive carts 24 hours per day over our spread of about 50 square miles!

You gave a very comprehensive explanation of equalization indeed! But putting in more energy than the batteries can hold is a bit of a stretch - kinda self contradicting. I believe I agree with your point though: that some batteries may not be totally charged when others are, so the equalization process will try to complete the charge on them while not harming (or further charging) the ones already fully charged. So the pack, as a whole, winds up with a better charge. And the cells are rejuvenated a bit, so will hold a bit more energy.

Disregarding the very unusual (unless you are doing electrical maintenance) condition of the OBC "losing its memory", I believe that the OBC will try to charge the pack to 110% of the energy units (EU) that were withdrawn since the last complete charge. It does this in a very intelligent fashion, starting at about 15 amps, gradually falling to about 10 amps by which time about 2/3 of the energy is replaced. Then it appears the series Silicon Controlled Rectifier (SCR) in the OBS takes control and the charge current is uniformly reduced to a few amps. At this point, the charge may stop if all the EUs are replaced, or continue with a equalization charge. Not many more EUs are added in this phase as it is just doing the things you have described to normalize the batteries - and most of the batteries should be fully charged, save the "poor" or abused ones. "Abused" being the ones supporting additional requirements like lights or radios.

I am intrigued by the problems you had with the OBC losing it's memory from due to long term battery removal. The 1999 OBC I disassembled had a Zilog Z8 microprocessor in it. Unlike current microprocessors, these babies were designs evolved from processors used to operate controllers - so they contained a storage area for the program (which survived no power of course) and scratchpad memory for computations - which was volatile, i.e. zeroed out if the power was removed. To store the EU and charging data, I believe Club Car used a small EEPROM. In the computer I took apart, it was a 93LC46B, which holds but a tidbit by today's standards, but enough for what they needed. After all, it they were going to use the OBC to validate exceeding the EU warranty criteria, it would not work well if the user merely had to disconnect the battery to erase the EU history.

It is possible that the transient data, such as concerning the last charge(s) is held in the Z8's scratchpad, as that will be replaced/renewed after a few charges. This is an annoyance when you are working on the system and leave the battery pack disconnected for more than a few minutes or so, as that data is lost. This probably led you, as it did me, to incorrect conclusions regarding how the charging system was performing. Like you, I lack the time or inclination to explore that issue further.

Being curious, I recorded the data sent out by the OBC by to the IR lamp that the Communications Display Module (CDM) and IQDM (only needed in IQ models) reads and displays, with the intent of perhaps building a CDM. The data stream was about 170 bits long and I was unable to decipher it, even knowing some of what it was sending. A CDM list price is "only" about $120, so if I really need one, I would buy it vs build it in a heart beat.


New Member
Thanks for the response Dr.

There are a few things different in the IQ version than the non-IQ. Im' told that the charging control itself is a bit different. Hopefully I will be receiving some documentation soon and I will share.

I read all your postings on the subject this past week and looked up the patents referenced. I have a better understanding of all this after doing so. I did a quick read of the patents but plan to go back and try to get a little more out of them.

Ref your comments item 20, I am surprised (or possibly a better word would be confused). The original equipment reducer (at least on the Villager-4 which comes stock as IQ with lights, wired differently than standard DS) connects to the negative battery lead after it passes through the current sensor of the OBC. My investigation led me to the conclusion that the reducer is nothing more than a dropping resistor in series to the lights. Depending on which lights were turned on the voltage drop across the reducer (dropping resistor), if I remember correctly, was between was between 3 and 5 volts making the dropping resistor around a 0.5 ohm. The aftermarket “converter/reducer”, both 10A and 25A I’ve had were much more, as you know. (inverter/xformer/rectifier [I assume])

I do want to clarify my statements ref OBC loosing memory. I guess I was getting to reasons for IQ OBC went into equalization each charge after batteries being disconnect for a length of time. The most of what I call “hard data” is stored and non volatile, however, the data requiring real time timing like hours/days since last charge, hours/days since last equalization, etc. is lost and resets to 0.

I have not requested a price for the IQDM, but had heard somewhere that it was nearly $1,000.00. If the CDM is only around $120.00 I may ask CC Dealer for a quote for the IQDM. (I would want to see instructions/documentation before I purchase. If it is like other CC documentation don’t think I would want it!)

You have much more research than I have. I wish CC published decent documentation didn’t protect as much as they do, then we could learn quicker.

Thanks again for you response AND thanks to PD for passing info along to you.