Date: Sun, 13 Jun 2010 10:44:52 -0400
Reply-To: Frank Grunthaner <FrankGRUN@AOL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Frank Grunthaner <FrankGRUN@AOL.COM>
Subject: Re: How to modify Bosch regulator for remote sensing.
In-Reply-To: <A5ED0905-9664-453B-94A4-843B89A60BF6@shaw.ca>
Content-Type: text/plain; charset=us-ascii; format=flowed; delsp=yes
Missed the rest of this topic, but I've been running the adj regulator
for more than 20 years without any problem. Beaucoup coulombs
transferred!
Frank Grunthaner
Sent from my iPhone
On Jun 12, 2010, at 9:05 PM, Alistair Bell <albell@SHAW.CA> wrote:
> A few years ago I tried an aftermarket adjustable volt. reg. Looked
> just like stock but for the addition of a tiny pot. that you adjusted
> to get output you wanted. It worked fine for a while but then
> something went wrong with it and it stopped outputting.
>
> I had it adjusted to 14.2 or so, when alt warm but not hot. Output
> did go down a bit after alt. got hotter.
>
> I think the concept is good, I just may have got a bad one. I'd like
> to try it again, it was only around $39.
>
> I bet my post is in the archives, I'll have a look.
>
> alistair
>
>
> On 12-Jun-10, at 1:41 PM, David Beierl wrote:
>
> At 03:57 PM 6/12/2010, mark drillock wrote:
>> One question I have is how high can the regulator be fooled into
>> driving the output voltage of the alternator at the alternator? If
>> during charging the wiring connection between the regulator sense
>> point and the alternator output leg is somehow lost, what happens?
>> In gas Vanagons the loss of the connection to the battery is a very
>> real possibility and the ECU could still be on the alternator output
>> side, so if the regulator could force the output voltage very high
>> without knowing it I wonder if something bad might happen. In the
>> stock configuration the regulator sees the charging voltage at a
>> point internal to the alternator so a loss of the connection to
>> battery does not mean a loss of the sense connection as well. Any
>> data on this?
>
> Excellent point. Something bad could definitely happen. On this
> unit and I presume all of them, if you float the input the alternator
> will go to full output which with a small load might be a very high
> voltage. The sense input draws 8-9 ma at 14.5v, so to failsafe it
> would need a suitable resistor across where the internal bus was
> cut. I'll figure out what suitable is, but it shouldn't be critical.
>
> Now if the sense lead is *grounded* that will definitely drive the
> thing to full output.
>
> I haven't addressed the situation yet of the alternator output no
> longer driving the battery, but the sense input still connected there
> -- effectively it's the same as floating the input, since it will be
> immediately carried down to the loaded battery voltage. Looks like
> the systematic solution to that would be to get the 30 terminals of
> the ECU/Fuel relays off the direct alternator wire and feed them from
> up forward somewhere, either the fuse/relay panel 30 terminal or
> direct from the battery.
>
> Another solution would be to use a diode to bridge the cut instead of
> a resistor. That way the internal regulator voltage should never go
> more than a diode drop above the regulator set point. Not ideal,
> would want a warning probably; but not instant disaster either. And
> put a quarter-amp fuse in the sense lead, so it would blow if the
> lead was grounded.
>
> Have I missed anything?
>
> Yours,
> David
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