It'd be interesting to know just when the failures happened... when the
connection was pulled off/switched, during the time it was disconnected or
when it was reconnected.

Cya,
Robert

----- Original Message -----
From: "Mark Drillock" <drillock@EARTHLINK.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Friday, November 10, 2006 10:33 AM
Subject: Re: Toggle off switch

> In the boating world they use a special external protection device added
> to the alternator terminals to prevent damage if the battery is
> disconnected. I think they are zener diodes, 16 volt. These short the
> output to ground when the threshold voltage is reached. Only good for
> very brief times, spikes in other word.
>
> http://www.emarineinc.com/products/alternators/zapstop.html
>
> This is a real concern in boats since they frequently have battery
> switches that allow for batteries to be disconnected and reconnected in
> different banks.
>
> I know of several cases of ECU failure when vehicles were driven with
> the battery disconnected. One happened at Syncro de Mayo a couple years
> ago. Someone driving to the event thought there was a problem with the
> battery and disconnected it while the engine was running. Shortly after
> the engine died and would not restart. They had it towed to the event
> where we determined the ECU was now dead and the alternator regulator as
> well. Someone else loaned them a spare ECU and I loaned them a new
> regulator/brush pack. They bought a new battery in town IIRC. I know of
> a carbed engine vehicle that lost the radio, clock, and various bulbs
> after the battery was disconnected on a trip.
>
> In both of the above it was a chicken and egg situation. Both batteries
> were disconnected because they seemed to smell funny. The alternator
> could have been the original problem.
>
> Mark
>
> John Bange wrote:
>
>>> Is that the problem John, or is it the electronic engine management?
>>
>>
>> Dunno. Could be all that stuff, really. All these new low-voltage
>> electronic things are a lot more sensitive to wild swings in voltage,
>> I guess. I know a lot of newer regulators are using smaller ICs
>> instead of the giant wads of silicon of yesteryear, so they might be
>> more touchy as well. I've never been able to get a definitive answer
>> on the whys of not disconnecting the battery beyond the citation of
>> voltage instability.
>>
>> --
>> John Bange
>> '90 Vanagon - "Geldsauger"
>>