Gents, newly converted to 12v gm generator on my stovebolt. Generator shop that converted and rebuilt the gen supplied an old school type regulator to go along with it. I was told by the shop that the regulator needed be trimmed or adjusted to the generator. Currently running a motorcycle battery in the roadster, generator either puts out way to much voltage or doesn’t charge. Shop showed me how to adjust the regulator by adjusting the internal spring tension after two visits back. They’re telling me the reason the adjustment is so finicky is the motorcycle battery. My intent all along was to run an Optima red top which I will install in a coupla days unless I hear on this forum that the Optima combined with the gen is a problem. Would really prefer not to use a lead acid if I can avoid it. Don’t care so much about getting right with shop if the regulator is the problem, just want the system to work. Two questions then, does anyone here have experience running an Optima with a GM generator? (I understand the Ford regulator is set up different?) Also, does the explanation I’m getting regarding the regulator kinda being on the razors edge with adjustment make any sense given the motorcycle battery?? Thanks, Al
I run a 12 volt generator with an Optima Red Top battery in my '32. Have been for years with no problems. It charges just fine. I am running a Ford generator but I am not aware of there being a difference between it and GM stuff. That being said, I do not claim to be an electrical expert by any means. And I am using an old school regulator.
Correct, generators and Optima batteries do not work together. You will either need to go alternator/Optima or generator/old school lead acid. You could go with the alternator that looks like a generator if you want the look, but it will cost you. This comes from 40 years' experience as an auto electrical rebuilder. Some I'm sure will disagree.
I'm assuming you have a 3 unit regulator. If so, it has a cut-out relay, a voltage regulator and a current regulator. If it doesn't charge at all, you need to see if the cut-out relay is closing. The generator will not charge with the cut-out relay points open. It needs to be adjusted so that the points close at about 12.0 - 12.3 volts. You can turn on the headlights with the engine running and monitor voltage, but a carbon pile is a lot nicer to use for a load to control the voltage. The purpose of the cut-out relay is to keep the generator from becoming a motor if the generator voltage output drops below battery voltage. Generator output voltage is low at idle. The voltage regulator is the relay device with a lot of turns of fine wire. You need to adjust the spring tension to get 13.5 to 14.2 volts at 1500 rpm and all accessories off. Once you get the voltage set, you need to put the cover back on and let the engine run for at least 10 minutes. The setting may change with the cover on. The current relay controls generator output current and it is there so that you don't overload the generator. It really needs to be set so that it opens when the current output is at the generator rating. It is the only part of the regulator that needs to be matched to the generator. You need to be able to apply a load to set it correctly.
uh...the Optima Red Top is a Lead Acid battery. It's AGM, rather than flooded, but the chemistry is the same.
For the record in my post, I never said that an Optima wasn't led acid I just said that if you were going to run a generator you need to run an old school lead acid battery. I'm obviously not an engineer I'm just a guy who has set up A LOT generators and regulators on the bench and on vehicle and always had problems with generators and AGM/Optima batteries, when we had problems with AMG batteries and the switch was made back to old school led acid batteries the troubles were cured. I can't argue on the level of chemical or electrical theory, so to Jim and others out there I would really like to understand why this has been the case for me and other rebuilders. Attending continuing education courses put on by rebuilding associations many stated the same thing. So, I really would like to understand this, and I am not being a smart ass or know it all, maybe some of you guys can help me out on this. AGM batteries require a special battery charger, right. Why is this and what with a generator could be causing problems in the real-world situations? Again, I really want to learn about this situation and why it has been known to cause problems.
AGM batteries have less internal resistance and can charge at x2-5 the amperage rate of a regular lead acid. Usually a regular charger will only take you up to 80% charge on a AGM.
On another note, since they have different charging requirements. I'm not that adapt on generators compared alternators. But without a maintained full charge batteries suffer from sulfation. Don't know if that's why you might be experiencing issues with it on a generator?
I’ve been running 2 cars with GM a generators and Optima batteries for years and never a problem. But, whatever. You can buy a Solid State GM style Voltage Regulator for a generator and no more messing with adjustments. https://www.qualitypowerauto.com/item_140/GM-Voltage-Regulators.htm
I find it real easy to believe that you would have trouble with AGM batteries and generators...even though the chemistry is the same, the construction of the battery is different, and the charging requirements are different. AGM batteries can take a faster charge when they're low, but can't tolerate overcharging when they're full. Kind of hard to make this work with a generator and mechanical regulator. I was just being pedantic, pointing out that an AGM battery is still a Lead Acid battery.
Jim, no offence taken or intended on my end; I really am interested in opinions on this from both sides. Also just willing to admit there are guys on this forum that are a lot smarter on the theory and engineering side of this than I am and really looking for answers. We have two members that have had no trouble at all, that goes against what I have experienced, that make the "why" even more interesting to me. Hell, I just learned a new word from you that I had to look up! So, I just "expanderdized" my vocabulary
I can also believe that a few guys have made it work. There's probably a "sweet spot" with the regulator adjustment that will give acceptable charging. It's probably not exactly how the battery is supposed to be charged, but close enough to not cause trouble. AGM batteries are showing up in new cars as original equipment, I got to replace one for a relative recently in a 5 year old car. They cost twice as much as normal batteries. But you can get them at walmart, so.....
I've got a gm Generator and a optima red top in my roadster.i adjusted the regulator to put out almost 14 volts at high charge and have had no problems in more than 10 years.
Well, I'm no expert on AGM batteries. I was talked into buying one for a motorcycle years ago with the promise of longer life which turned out to be false; it lasted about 1/2 the time of a conventional lead-acid (at about double the cost). Told that was an outlier, I tried another one with the same results, so I've steered clear of them ever since. I typically get 7-10 years service (or more) out of 'regular' lead acid batteries but I also take care to make sure they're fully activated before putting them into use. For all the touting about how great AGM batteries are, I just don't see it. My understanding of them is they need a higher current input to achieve a full charge. Generators are current-limited, constrained by their construction. Most are 30 amps, to get more power you need a physically larger unit. Those are rare, the few I've seen were for large luxury cars like late '50s/early '60s Lincolns or Caddys. If you try turning the current output up higher, brush/commutator life will suffer and you may not gain all that much anyway due to magnetic saturation of the pole windings. Turning up the voltage won't cause issues with those, but can have negative effects on other components, although that will ensure that the maximum current available goes into the battery. They also don't have as 'smooth' an output as you typically have only 24 'pulses' per armature revolution due to their single-phase design. Alternators address most of these issues. They typically have 30 'field' pole windings (which are actually where the output is made) with six poles on the rotor. This gives you 180 pulses per revolution, over seven times as many. Much, much smoother, and I suspect this is the main difference for AGM charging. Plus, because the windings are three series-wound groups of ten, each individual pole winding only needs to produce 1/10 of the total output. So where a generator has to strain to produce its 30 amp output in its single winding at a time, an alternator need only produce 10 amps per pole for a 100 amp output. This illustrates why what gauge you use to monitor charging system health matters. Generators can produce full voltage at full current or if worn brushes are limiting current output, so an ammeter is what you want. Alternators can still produce 2/3 of their current output if a diode fails, an ammeter won't show this unless you're using all of that output. But losing 1/3 of your voltage output will definitely show up on a voltmeter, so that's the choice here.
jaracer, so the only item I’ve adjusted is the voltage regulator but can’t get it to be consistent, it’s either not charging or putting out 16 to 18v with tiny adjustments. As I said in my original post the shop that rebuilt the unit is blaming this sensitivity on the motorcycle battery currently in place. I’ll get it close and next thing it’s either not charging or putting out way too much voltage and I can smell the battery cooking. I wanted the agm to eliminate the lead acid corrosion issues I’ve encountered with flooded batteries. Given all the opinions above I’m not sure whether I should reconsider the Optima yet and go with flooded? Was hoping that the shop was right and the charging system would settle down once the motorcycle batt was outta the system. Thanks the thoughts!
Steve, so I’m stuck with the gen as I’m not willing to hang an alternator on the side of my 30 roadster, Now I get to reconsider my aversion to the lead acid flooded batts! Almost no electronics on the roadster other than lighting and ignition. Al
squirrel, hav a coupla very early 2000’s BMw x5’s that we run, one as a grocery getter jalopy and the other my daughter’s driver for the past nine years. Both have large AGMs in the rear which were the type installed when new, so to your point BMW has been using them for more than 20 years. I’ve had great luck with these batteries including multiple episodes when for one reason or another the batteries were run flat, they seem to survive these episodes with no ill effects. Completely different environment I understand but that was one of the reasons I was leaning towards using one in my roadster. Hav red tops as well in two of my 60’s fords, but those both hav alternators! Thanks your thoughts, Al
I have two late models with them, we'll see how they do. When we used them in the robots, they hold up to some abuse, but usually get iffy after a few years. I usually get 5 years at least out of normal car batteries, but I change them when they get that old, just to prevent unexpected problems. It's a system that works well for me. Good luck with your decision.
I’m running mechanical regulators on the generator cars. Running solid state on a 1969 alternator car.
I am curious as to the problems you have run into. As I mentioned earlier I have been using this set-up for 10-12 years on a regular basis and it has done well for me.
Both burnt fields or armatures throwing solder. I always covered one warranty job on burn up even if I didn’t install new fields in the rebuild. I would eat one job but not two. When digging deeper found out there were more warranty jobs with AGM batteries. When and if the customer switched back to old school led acid batteries the troubles stopped. We would not let a generator rebuild go out the door without setting up the generator and regulator on the test bench. Also had other rebuild shops at trade show conferences say the same. At the end I would not warranty a generator rebuild if a AGM battery was used with it. Just my experience.
The last battery I had in my 57 T-Bird was an Optima in disguise. It was an original battery case with an Optima inside. I had this in the car for the last 7 or 8 years I owned it. The car still had the generator charging system. The Optima was starting to get a bit weak, but it was 7 or 8 years old. I think the Optima will be fine with the generator.
So thought I would follow up with the final resolution to my charging issues. As was related when I first initiated this thread to explore the issues I was having with my newly rebuilt 12v gm generator. The generator was rebuilt and converted to 12v by a local gen shop. The rebuilt generator was hanging on the stovebolt in my roadster and had been installed with a brand new voltage regulator sourced from the gen shop. The problem was that right from the first install, the system was seriously overcharging, running as high as 18v at rpm. I as well as the gen shop were unable to adjust the voltage to a reasonable range. Initially it was suggested by the shop that the problem was the fact that I was running a motorcycle battery. Replaced that battery with an Optima red top, same results. Gen shop offered another voltage regulator, installed that with the same results. I would be able to make a slight adjustment to the voltage output but as soon as I got close to a reasonable voltage the system would cease charging. Was able to drive the car just on the battery for the last month as it currently has a very minimal electrical system and would trickle charge when I got home. The mechanical voltage regulators currently on the market are constructed very simply, requiring bending the spring mounting tabs to adjust voltage and amps. Both regulators I had been supplied were stamped “made in USA”. The resolution turned out to be an old 35amp voltage regulator I found at Hershey a week ago. Googled the part number, was off late 50’s to early 60’s Buick and had been rebuilt at some point in its life as it had an old sticker declaring such on the cover. The old regulator while structurally and electrically similar to the new ones was far better constructed with more robust components and adjusting screws for all parameters. It had obviously been used since being rebuilt. Bolted that thing in the roadster and the charging system works perfectly! So it appears that there was an issue with the two new regulators. Grateful to have that issue behind me. Al
I have been running my 12-volt stock 57-vette generator for over 10 years with a red top optimum battery, and I never had an issue in charging it.
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