Hi All,

I'm having some difficulty testing the voltage regulator on my '64 122, or rather, making sense out of the instructions in the Haynes manual. Does anybody know of a website that describes the process in plain English? As a second to that, anybody know where I can get a replacement for the Bosch regular that's on the car? IPD has some regulators, but they all seem to connect with a three-pronged plug, while on mine, the various leads from the generator and battery are screwed to the regulator.

Thanks a lot,
F.R.

The IPD 3 prong regulator is for an alternator. Sounds as if you want a Bosch type for a dynamo/generator. I gave up looking for one on the IPD site as you have to jump through hoops just to get to the next page. Browsing doesn't seem to be possible. Haven't been there for a while but to me it's gone backwards.
Try Mike Dudek at http://irollmot.ipower.com/oscom/product_info.php?cPath=26_30&products_id=738&osCsid=2ee0287eaf0b149c2580796715ad481f
Expensive! Put up a "Wants" request up here on BB.

Thanks Derek. That looks like the unit. Thanks for the advice on the "wants" listing.

Cheers,
F.R.

Hmm. Doing a little more testing here, with the voltmeter on the battery terminals.

With the engine off, the meter reads 12 volts. With the engine at idle, it stays at 12 volts. As I rev the engine gradually, voltage goes up to about 13.2-13.5 volts and levels off.

Since the volts level off, the voltage regulator is working, right? But what about the maximum voltage of somewhere between 13.2 and 13.5? Is that normal, or is it low? And does it suggest a weak generator?

Thanks again,
F.R.

A quick test to determine whether you're dealing with a short or other unknown drain on the battery:

With the car off, disconnect the negative battery terminal. Connect a test light between the [removed] terminal and the negative battery post.

If the light comes on, there's an electrical draw. If you have a clock, or a stereo that uses a memory wire, or any other thing you know of that's always active, disconnect it. If the light stays on, you have a drain. Remove the fuses one at a time - if the light goes out when you remove one of the fuses, you can then narrow your search to include only the circuits connected to that fuse.

This won't do anything to fix a dud battery, nor does it address whether or not your charging system is or isn't adequate. But it'll allow you to find out whether any of your symptoms are related to a constant drain on the battery.

Best,

Cameron
Rose City

Hello,

Anything over 13 volts is ok.

--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502

Thanks Eric. Hmmm. So if it's showing over 13 volts, and the battery is good (at least according to the guys at Kragen, who hooked it up to their tester), any idea why the battery would die three weeks after it was fully charged? I checked to see if I had any accessories on -- the glove shelf light, etc. -- but as far as I know, there are no such vampires.

Thanks again,
F.R.

Floyd;

I suspect (as usual, in a half century old charging system of a vintage Volvo) there are several things conspiring to give problems...so sorry for the seeming discontinuity of my thoughts here, but they typically all tie together to result in the symptoms you are experiencing...

A high power load left on would discharge the battery in a few hours, but short of the headlights, there are just not that many in a (stock) 122...and hopefully you would notice those being ON in short order... (Add-on high power stereo amps under slave control of the stereo head are NOTORIOUS for drawing high OFF/standby current...wire them with a separate power switch or a slaved Ignition relay).

...a low power load could possibly discharge Battery in three weeks, but again, you would notice the courtesy light ON too...that's why I still suspect the Battery...have a LOAD TEST of the battery performed ...older batteries can have a high self-discharge rate, and frankly, with an OE Generator, they never really get FULLY charged...read on...

To assure no parasitic loads are discharging the battery, charge it fully with a 110VAC powered charger over night, disconnect it and wait those three weeks and try starting again...that will test the long-term storage capability of a truly fully charged Battery and self-discharge rate and will eliminate the car electrical system from suspects.

If you are measuring >13 volts anywhere on the electrical system at elevated RPMs, that confirms the Generator is putting out power and VReg is working fine (and that is a practical test of the VReg...further functional tests require special equipment and techniques), but it's not quite enough...exactly WHERE you measure this voltage is important, because all voltage drops across less than perfect connections along the charging path will serve to decrease the current with which the battery is being charged...voltage measurements should be made right at the clean and snug connections of the battery...and they should be compared to voltage measurements taken at the B+ terminal of the VReg (Neg of meter stays at Bat-), and compared...more than about .5V difference means a high voltage drop along the way which results in a decreased charging of the Battery.

(And this plays into and supports why I much prefer an Ampmeter in a car to a Voltmeter...an Ampmeter connected per the standard "H" wiring diagram*, to show charging current gives exactly the information I need: Charging or Discharging (and magnitude, but that is secondary)...Voltage measurements on the other hand need to be interpreted for what they mean with respect to Battery charge...where is the voltage being sensed, what other loads are on...not to mention that from 10% to 90% charge of a battery occurs within .75V)

My first recommendation is to preventatively disconnect, abrade clean, and reconnect with a slight film of ACZP, and tighten ALL connections in the charging current path...that is: Battery, Vreg, Big Bolt at the Starter, FuseBlock, Ignition Switch and Ground Strap at engine, because in an OE Generator system, there is simply not enough output margin to accommodate loosing a few tenths of a volt at several less that perfect connections. This is where the Alternator conversion has proven itself time and again, and this is not to be meant as an advertisement (but in fact it winds up being one!), but a vintage Volvo with a 60A output Alternator has PLENTY of charging system margin that it simply doesn't care if you're loosing a couple of tenths of a volt along the line somewhere, or if you are only driving around town at low RPMs...it'll keep that less-than-new Battery well charged under virtually all conditions, and you don't need to worry or even think much about it, whereas an OE Generator equipped car has very little margin indeed and so many things working against it after 50 years, including low output at low RPMs, that the less than new Battery RARELY gets fully charged...and when you try starting with it, its own internal resistance combined with a less than full charge means that you get only a few seconds of decent cranking...if you can't manage to start the motor in that time, you're considering taking the modern car, and thinking that maybe it's time you stopped messing around with ancient vehicles...

Bottom line...if you want to keep your Generator, you better also have a new Battery, assure that all aforementioned electrical connections are as clean and tight as possible, and remember that every drive you take should include at least a 5-10 minute high RPM session...I'm done preaching now.


* Ref: http://www.sw-em.com/elecramb.htm

Hi Ron,

Thanks for the exhaustive explanation. I've already cleaned up all the connections (generator, regulator, battery, ground, etc.) and that didn't seem to make much of a difference. The battery in this case is 9 years old, but the folks at Kragen told me it was good after testing it thoroughly. I imagine they would have taken the opportunity to sell me a new one if it was in the least bit ailing. The long-term storage test is a brilliant idea...only problem is it would be tough to not use the car for 3 weeks straight. In an earlier post, Eric suggested that even though the voltmeter is showing on the order of 13.5 volts at the battery terminals with the engine revved up, there might be a shortage in the amp department. Any idea how to go about testing amperage, and where to do that?

Cheers,
Floyd

9 years old?. I have never gotten 9 years out of a battery. That's some battery
Dean

Yep. Per the date of manufacture stamped on it. Maybe it's because I drive the car regularly and did a deep cycle charge from time to time. But otherwise it was nothing special -- just a Kragen unit.

F.R.

"9 years old?. I have never gotten 9 years out of a battery. That's some battery."

That might happen more often than you realize. I replaced the original Mopar battery in my 2001 Dakota R/T just this past fall. And the battery was date-coded late 2000, which is when the truck was born... so it lasted 12 years. I've also gotten 10 years out of an original battery in a John Deere lawn tractor, which is a horrible environment for a battery - lot's of vibration, don't ya know. :)
--

Gary L - 142E ITB race car, 73 1800ES
BlueBrick Racing Website
YouTube Racing Videos

Floyd;

Confirm exact magnitude of the the charging/discharging current with an AMPmeter connected per the "H" diagram...anything else is by indirect approximating methods and could be just plain wrong if an unusual condition (like a poor connection) exists...that is why assuring connections is so important...

It's also not possible to measure that Voltage when it is connected to the battery (in this case, a load) without a charging current flowing (because that output Voltage of the charging system is a higher Voltage than the battery could ever have on its own)...the exact amount is impossible to know without measuring, but current is bound by Ohms Law! Amps flow as a resultant of the difference in Voltage at the output of the Charging System (in general terms, and without going into laborious details, set by the Voltage Regulator), and Voltage of the Battery (set by its chemistry and state of charge), so if you measure 13.5V across the battery posts, by definition the charging system is doing its job, and so if the battery does not hold a charge, the only suspect left is the battery...the guys at Kragen probably did a "Load Test" where they apply a high load and watch what the Voltage does...if it doesn't collapse in X number of seconds, they call it "OK"...they certainly didn't do a long-term charge holding test, and that is where your old battery is weak as you have stated.

13.5V across the battery, is also consistent with a high internal resistance (which sounds right for a old battery with sulfated plates).

OE batteries fitted to cars in the factory seem to be of a higher construction quality that often makes it past 5 years. Replacement batteries are engineered to the nit so that after 60 months, they are on borrowed time.

I think it's time for a new battery!

Ron,

You nailed it. It was the battery. I replaced it a month ago, and no problems since.

Thanks for everyone's input, and the electrical education.

Much appreciated,
F.R.

Ron,

Thanks again for your advice and insights. This battery is 9 years old, so maybe it's just tired like you suggest. Like you say, I would have thought that if it was showing 13.5 at the terminals when running, that the generator and regulator were doing their thing. Time for some new lead.

Thanks,
Floyd

Thanks Eric. Hmmm. So if it's showing over 13 volts, and the battery is good (at least according to the guys at Kragen, who hooked it up to their tester), any idea why the battery would die three weeks after it was fully charged? I checked to see if I had any accessories on -- the glove shelf light, etc. -- but as far as I know, there are no such vampires.

Thanks again,
F.R.

Hello,

Even though the generator is producing 13+ volts, it may not be producing enough amperage to charge the battery or if the wiring is suspect you may have problems with connections.

Unless you own or have access to some special measuring tools, you might consider taking the car or just the generator to a generator/alternator shop and have them test the amperage output.

We have a tool that measures the amperage inductively so no wires have to be removed.

If you do not have a local generator/alternator shop, I am sure you can find an independent repair shop that has the tools to help diagnose the problem.

FYI, we have an electronic voltage regulator to replace the mechanical voltage regulators used with a generator so no moving parts to fail or get stuck.

--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502