Philes' Forum by Vic Lucariello

Hello, bimmerphiles! This month I have a couple of questions I received via the Internet, and some feedback on last month's column on battery maintainers.

Last month I mentioned that Northern Tool and Equipment offers an alternative to the J. C. Whitney battery maintainer I have had so much success with. I asked for any of you who had experience with the Northern maintainer to contact me.

Well, Joe 'E-Male' Getcy, erstwhile Chapter VP, came out of the woodwork and sent me a letter in his very own hand! 'Ol E-Male has been using a Northern 'SureCare' [TM] maintainer on his 911, and he is happy with the maintainer's performance. Joe says that the SureCare keeps the battery charged to a slightly highervoltage than does the Whitney maintainer, but he has not had to add any makeup water to his battery. Also, he says that he likes the Northern's LED indicator because it tells you if things are connected and operating correctly and that the battery is capable of accepting a charge. J. C.'s maintainer does not have this feature.

E-Male was even kind enough to include a photocopy of Northern's instructions, which indicate that their maintainer is imported by VDC Elecronics of Englewood, NJ [VDC Model # 12121D], and has a 5-year warranty. J. C.'s maintainer is also imported, but has no stated warranty. However, I did have a J. C. maintainer which failed when nearly new, and they replaced it.

Given that both maintainers are the same price [$20], it appears that the Northern item is a better value. Also, I guess the rumors of E-Male's demise are somewhat exaggerated.

[Thanks, E-Male. This doesn't get you off the hook for the you-know-what, though!! Also, you may see my response to your demand for a salary on my web page: www.byte_me.com!]

There was a recent thread on the M3 List pertaining to engine coolant. One Lister, in response to a post which suggested that a 50/50 mix of water and ethylene glycol coolant was the recommended concentration, asked, "If 50 % coolant is good, why not use 100% coolant?" Here is my response:

According to an article in the October, 1998 Motor Trend Magazine, pure [ethylene glycol-based] coolant freezes at 0 F and has [at 200 F] only about 65 % the heat capacity of pure water. The article also states that the heat capacity of a 50/50 mixture is about 90 % of pure water. [Obviously, a 0 F freeze point is too high for vehicles which are outdoors in our climate, and a heat capacity of only 65% of water will not cut it either.] From this, one may estimate the heat capacity [Technoids: specific heat] advantage of pure water over a 50/50 mix at about 10%. This means that pure water will absorb 10% more heat for the same temperature rise. 10 % can easily make the difference between a boilover or no boilover. However, the 50/50 mix boils at a higher temp than pure water, so there is a trade-off in terms of heat capacity vs. boiling point.

In my garaged M3, I run a 25/75 mix of distilled water and coolant with a shot of Redline Water Wetter [WW]. In my 2002 Club Racer, I run distilled water and WW. As I understand it, WW is supposed to effectively increase the coolant's heat capacity by increasing the heat transfer between the engine and coolant WHEN THERE ARE VAPOR BUBBLES FORMING ON THE METAL. I am not sure, but I believe the WW is supposed to allow a higher heat flux before the phenomenon of 'departure from nucleate boiling' [DNB-Sorry for another technical term, but if you read this far, you asked for it] occurs. When DNB occurs, metal temperatures soar.

There are differing opinions on the efficacy of WW. My own opinion is that the WW can make a difference on a marginal cooling system. If you have had experience with it, please let me know about it.

I received the following from Elihu Savad. Please excuse the non-BMW content. The info really applies to most modern cars:

"I had mentioned to you the problems I had experienced with my Son's '95 Saturn. The alternator had crapped out at 28K miles, and I found out that this is not an uncommon occurrence. This happens frequently to the CS alternator, used in many GM cars, when heavy electrical loads cause overheating of the diodes due to inadequate capacity and/or inadequate heat sinks, as well as rear bearing failure. The only fix seems to be to replace the alternator, and be careful about turning on all the electrical accessories at once. Anyway, my son was anxious about a repeat failure, so I got him a cheap digital voltmeter that plugs into the 12v [cigarette lighter] socket. I told him that if the voltage with the engine off was about 12.5v and 14v or so with the engine running, all was well.

"I thought I would test the unit on my E30 M3 just to see if the meter was working, and I got a surprise: the voltage with the engine off was 12.2v and running fell to 11.7! I then noticed that the battery warning light did not light up with the engine on or off. I checked the battery with a hydrometer and found it quite low, about 1.2; apparently, I had been driving around like this for a while, but I would not have been able to do so for much longer. I checked the alternator connections and found that the smaller positive lead was quite floppy in its rubber boot. A gentle tug pulled the wire right out! I replaced the terminal end and reconnected it to the alternator. Now, with the engine running, I get about 13.7v [,and the 'battery' lamp illuminates with the ignition on and extinguishes when the engine starts]. I know the alternator it putting out, but I don't know if the regulator is functioning properly. What is the spec. voltage for this alternator? My other cars measure at 14.1v to 14.3V.

It seems a lucky coincidence that I got this J.C.Whitney accessory. Inthe future, I will check dash lights more carefully to see what DOESN'T light up."

The readings on your M3 are about right. For some reason, the voltage regulator s in BMWs seem to be set a bit lower than those in domestic cars.

I would expect your Saturn to indicate about 14.7 volts with a fully charged battery, engine running, and no accessories on. Turning on all accessories should drop it to about 14.3. What you need to be careful of on many cars is turning on a lot of accessories when the battery is not fully charged. EG: Crank car on cold morning and immediately put on lights, wipers, rear def, et al. This has been known to fry the alternator. The worst case is to jump start a car with a dead battery, then drive away with the heater, defroster, and wipers running. This can damage even a Bosch alternator.

On the M3, I would expect about 13.9/13.6 v under the same conditions.

You observed what you did on the M3 because in order to illuminate, the 'battery' lamp requires a complete circuit to and through the alternator via the small wire you had the problem with. Moreover, this wire supplies the field current to get the alternator to begin producing current. When this occurs, the alternator switches to its own internal supply of field current, an equal voltage exists on both sides of the lamp and it goes out. From this point on the alternator produces its own field current. This is typical of most modern passenger car alternators I am familiar with. The term 'battery' lamp is a misnomer, since the lamp tells you nothing much about the battery. What the lamp really indicates, provided the circuit is intact, is that the alternator is not charging the battery.

Before you fixed the wire, your alternator was not receiving its start-up field current, and there was no complete circuit for the 'battery' lamp. So, you correctly deduced that you were running on battery power only [I agree for not much longer].

Here are a couple more things to check on the M3.

1. With the engine running and headlamps on, increase RPM to 2000 and measure the voltage drop between the alternator case and the engine block. Should be maybe 0.1 v.
2. Similarly, measure the voltage drop between the alternator battery terminal stud [the larger wire]and the battery + term. [requires a long test lead]. Should be maybe 0.4v.

Whew! If anyone gets the award for the most comprehensive description of a problem, it is surely Dr. [Of Autocrossing] Savad!!

Anyone wishing to contribute to Philes' Forum should contact me via the info on the masthead. I'm interested in tech tips, repair /maintenance questions and/o r tips, dealer horror stories, product evaluations, etc. Please call before 8 PM, and if you leave a message, PLEASE INCLUDE A DAYTIME PHONE NUMBER. Also, please be patient, I try to return every phone call, but it sometimes takes awhile. If you don't hear back from me within a few days, please call again. The best way to contact me is via e-mail.

Copyright 1998 - V.M. Lucariello, PE