I have a 40 amp battery charger that has a 5 position switch to select
the battery charging voltage. Works great. Allows steps from about
13.2 to 17 volts. Prob done by a multi-tap transformer?

Trouble is - AC voltages in Mexico can be as high as 128-130 VAC and
other places can be as low as 105 VAC. The charger reacts by changing
the battery charging voltage up or down - a little but enough to vary
the DC amps that get to the batteries. I'm not going to replace the
charger.

I'm looking for a cheap variac/scr/triac something gizmo that I can
wire into the AC line to the charger and make the effective voltage
(RMS value?) go up or down by +/- 10% or so. The AC in is about max 9
amps. It could even be a big wired wound variable resistor I suppose.
Then I can set the AC line voltage to what my genset puts out and use
the charger at it's max 40 amps all the time.

Any ideas or products. Preferably cheap and never needs replacement
like the 27 years old charger.

(No I'm really not going to replace the charger.)

Are you kidding? Forget about it and forget about the voltage variation.

--
_______________________________
Joel, P.E.



"Panama" wrote in message
...
I have a 40 amp battery charger that has a 5 position switch to select
the battery charging voltage. Works great. Allows steps from about
13.2 to 17 volts. Prob done by a multi-tap transformer?

Trouble is - AC voltages in Mexico can be as high as 128-130 VAC and
other places can be as low as 105 VAC. The charger reacts by changing
the battery charging voltage up or down - a little but enough to vary
the DC amps that get to the batteries. I'm not going to replace the
charger.

I'm looking for a cheap variac/scr/triac something gizmo that I can
wire into the AC line to the charger and make the effective voltage
(RMS value?) go up or down by +/- 10% or so. The AC in is about max 9
amps. It could even be a big wired wound variable resistor I suppose.
Then I can set the AC line voltage to what my genset puts out and use
the charger at it's max 40 amps all the time.

Any ideas or products. Preferably cheap and never needs replacement
like the 27 years old charger.

(No I'm really not going to replace the charger.)

Are you kidding? Forget about it and forget about the voltage variation.

--
_______________________________
Joel, P.E.



"Panama" wrote in message
...
I have a 40 amp battery charger that has a 5 position switch to select
the battery charging voltage. Works great. Allows steps from about
13.2 to 17 volts. Prob done by a multi-tap transformer?

Trouble is - AC voltages in Mexico can be as high as 128-130 VAC and
other places can be as low as 105 VAC. The charger reacts by changing
the battery charging voltage up or down - a little but enough to vary
the DC amps that get to the batteries. I'm not going to replace the
charger.

I'm looking for a cheap variac/scr/triac something gizmo that I can
wire into the AC line to the charger and make the effective voltage
(RMS value?) go up or down by +/- 10% or so. The AC in is about max 9
amps. It could even be a big wired wound variable resistor I suppose.
Then I can set the AC line voltage to what my genset puts out and use
the charger at it's max 40 amps all the time.

Any ideas or products. Preferably cheap and never needs replacement
like the 27 years old charger.

(No I'm really not going to replace the charger.)

"Panama" wrote in message
...
I have a 40 amp battery charger that has a 5 position switch to select
the battery charging voltage. Works great. Allows steps from about
13.2 to 17 volts. Prob done by a multi-tap transformer?

Trouble is - AC voltages in Mexico can be as high as 128-130 VAC and
other places can be as low as 105 VAC. The charger reacts by changing
the battery charging voltage up or down - a little but enough to vary
the DC amps that get to the batteries. I'm not going to replace the
charger.

I'm looking for a cheap variac/scr/triac something gizmo that I can
wire into the AC line to the charger and make the effective voltage
(RMS value?) go up or down by +/- 10% or so. The AC in is about max 9
amps. It could even be a big wired wound variable resistor I suppose.
Then I can set the AC line voltage to what my genset puts out and use
the charger at it's max 40 amps all the time.

Any ideas or products. Preferably cheap and never needs replacement
like the 27 years old charger.

(No I'm really not going to replace the charger.)

In one radio station in which I worked, they had some regulating transformers
that
would give 118 vac out with 95-135 volts in. There were taps to run it off 220,
which
they did, with an input of + or - 20 volts for 230 out. There was one thing that
should
be noted is that they get very warm if running near the rated load. They also
used to
hum a bit.

Leanne

I also have used the regulating transformers at large commercial on shore
radio/computer installations. Sola was the brand we used, one on each leg of
3 phase shore power. Some critical units had small single phase
transformers mounted in the rack. They covered about 95-135 volts in for
constant output. However, they take several cycles of power change for the
change to be seen at the output. I got into trouble having a large UPS unit
feeding the transformers, as the transformer change was slower than the UPS
and we got into a voltage bucking problem. Ended up taking the transformers
out and just using the UPS. Do a web search for Sola line regulator
transformers (they are really a mag amp autotransformer device). E-bay has
them from time to time.

Doug K7ABX

"Leanne" wrote in message
...
In one radio station in which I worked, they had some regulating
transformers
that
would give 118 vac out with 95-135 volts in. There were taps to run it off
220,
which
they did, with an input of + or - 20 volts for 230 out. There was one
thing that
should
be noted is that they get very warm if running near the rated load. They
also
used to
hum a bit.

Leanne

On Tue, 25 Nov 2003 22:14:36 GMT, "Doug K7ABX"
wrote (with possible editing):

I also have used the regulating transformers at large commercial on shore
radio/computer installations. Sola was the brand we used, one on each leg of
3 phase shore power. Some critical units had small single phase
transformers mounted in the rack. They covered about 95-135 volts in for
constant output. However, they take several cycles of power change for the
change to be seen at the output. I got into trouble having a large UPS unit
feeding the transformers, as the transformer change was slower than the UPS
and we got into a voltage bucking problem. Ended up taking the transformers
out and just using the UPS. Do a web search for Sola line regulator
transformers (they are really a mag amp autotransformer device). E-bay has
them from time to time.

Doug K7ABX

I think there are two kinds. One type uses a swinging core in the
transformer and works by adjusting the output voltage. The other uses
what is known as a "ferroresonant" transformer which works by
saturating the core at resonance with a non-polarized capacitor which
keeps the output steady regardless of input voltage swings. In a
marine environment, I'd opt for the latter as there are no moving
parts.
--

Larry
Email to rapp at lmr dot com

On Wed, 26 Nov 2003 14:28:34 GMT, L. M. Rappaport
wrote:


I think there are two kinds. One type uses a swinging core in the
transformer and works by adjusting the output voltage. The other uses
what is known as a "ferroresonant" transformer which works by
saturating the core at resonance with a non-polarized capacitor which
keeps the output steady regardless of input voltage swings. In a
marine environment, I'd opt for the latter as there are no moving
parts.

However, you can have problems when using a ferroresonant tranformer
or charger on a genset or other off-grid power sources, since the
ferroresonant transformer depends on the power frequency being very
close to 60 Hz. If the frequency shifts, the transformer output
voltage will also vary.





--
Peter Bennett, VE7CEI
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

On Sat, 29 Nov 2003 12:02:41 -0800, Peter Bennett
wrote (with possible editing):

On Wed, 26 Nov 2003 14:28:34 GMT, L. M. Rappaport
wrote:


I think there are two kinds. One type uses a swinging core in the
transformer and works by adjusting the output voltage. The other uses
what is known as a "ferroresonant" transformer which works by
saturating the core at resonance with a non-polarized capacitor which
keeps the output steady regardless of input voltage swings. In a
marine environment, I'd opt for the latter as there are no moving
parts.

However, you can have problems when using a ferroresonant tranformer
or charger on a genset or other off-grid power sources, since the
ferroresonant transformer depends on the power frequency being very
close to 60 Hz. If the frequency shifts, the transformer output
voltage will also vary.

I haven't the experience, but you are probably correct. Resonance
would depend upon the "Q" of both the transformer and capacitor.
Another important consideration is that while ferroresonant
transformers might work for charging batteries, since they operate
using square waves (core saturation), they are usually not recommended
for running electronic equipment or anything sensitive to spikes.
Battery charging is ok, however, since the battery acts like a big
sink for spikes.
--

Larry
Email to rapp at lmr dot com

On Sat, 29 Nov 2003 12:02:41 -0800, Peter Bennett
wrote (with possible editing):

On Wed, 26 Nov 2003 14:28:34 GMT, L. M. Rappaport
wrote:


I think there are two kinds. One type uses a swinging core in the
transformer and works by adjusting the output voltage. The other uses
what is known as a "ferroresonant" transformer which works by
saturating the core at resonance with a non-polarized capacitor which
keeps the output steady regardless of input voltage swings. In a
marine environment, I'd opt for the latter as there are no moving
parts.

However, you can have problems when using a ferroresonant tranformer
or charger on a genset or other off-grid power sources, since the
ferroresonant transformer depends on the power frequency being very
close to 60 Hz. If the frequency shifts, the transformer output
voltage will also vary.

I haven't the experience, but you are probably correct. Resonance
would depend upon the "Q" of both the transformer and capacitor.
Another important consideration is that while ferroresonant
transformers might work for charging batteries, since they operate
using square waves (core saturation), they are usually not recommended
for running electronic equipment or anything sensitive to spikes.
Battery charging is ok, however, since the battery acts like a big
sink for spikes.
--

Larry
Email to rapp at lmr dot com