Here’s one of those wild ideas that will probably get shot down
(probably by Larry) but some of us may learn something from the
patterns the flames make.

I’ve got a nice, temperature compensated, battery charger for running
off the AC at dockside. When running for long periods under power
however, my expensive AGM’s are being driven by the alternator which
isn’t significantly different from the ones on the Model T.
Retrofitting my larger spare with an expensive, 3 stage, temperature
compensated regulator is on my wish list.

However, why not disconnect the alternator from the battery circuit
and run it to an inverter large enough to run the dual 10 amp battery
charger? The battery charger then plugs into the AC and one charger
does it all. If I switched off the battery charger, this would also
give me some AC power when the engine was running.

I don’t use AC much and don’t care much for making it by drawing down
my batteries. I wouldn’t mind having the engine idling for the
infrequent times I would like AC away from the dock.

If I could make this work (by switching off battery charging) well
enough to heat up my small hot water heater, which would also be
getting waste exhaust heat (although not much with just 20 HP) , it
would be the nuts.

--

Roger Long

Disregarding the possible merits of the idea, the problem is going to be
matching the alternator output to the inverter. The inverter expects to
see 12 VDC (nominal) but could be designed (could have been designed) to
accept the multi-phase, higher-voltage, frequency-dependent-upon-engine
speed, alternator output.

Your job, should you agree to accept it, is to query the inverter
manufacturers to determine whether their products will accept
unprocessed alternator output. Having established that such units are
commercially available, we can then debate whether the arrangement is a
"good idea".

By way of a preview, depending on an awful lot of awful things, your
Model T-era charging may not be improved much by even the most costly
charger on the market. You might try to establish whether it is the
alternator/regulator combination that is causing your charging
irritation or the unwillingness of your expensive AGM's to accept bulk
charge at the exalted rates of which we dream.

Chuck



Roger Long wrote:
Here’s one of those wild ideas that will probably get shot down
(probably by Larry) but some of us may learn something from the
patterns the flames make.

I’ve got a nice, temperature compensated, battery charger for running
off the AC at dockside. When running for long periods under power
however, my expensive AGM’s are being driven by the alternator which
isn’t significantly different from the ones on the Model T.
Retrofitting my larger spare with an expensive, 3 stage, temperature
compensated regulator is on my wish list.

However, why not disconnect the alternator from the battery circuit
and run it to an inverter large enough to run the dual 10 amp battery
charger? The battery charger then plugs into the AC and one charger
does it all. If I switched off the battery charger, this would also
give me some AC power when the engine was running.

I don’t use AC much and don’t care much for making it by drawing down
my batteries. I wouldn’t mind having the engine idling for the
infrequent times I would like AC away from the dock.

If I could make this work (by switching off battery charging) well
enough to heat up my small hot water heater, which would also be
getting waste exhaust heat (although not much with just 20 HP) , it
would be the nuts.

There would probably have to be another voltage regulator in between
the alternator output (from it's standard regulator) and the inverter.

I bought one of those little inverters that go in a cigarette lighter
so I could charge extra cell phone batteries in my car. I have an
unswitched outlet that is on all the time and the charger works great
in that. As soon as I turn the engine on however, the light on the
charger blinks rapidly back and forth from green to red. (charging to
charged). I'm not sure if it's charging but I haven't wanted to risk
the $70 battery and $40 charger to find out.

Sounds like you are pointing me towards similar problems on a much
bigger and more expensive scale.

BTW my AGM's are working great the way I am using them, short motoring
periods and an overnight plug in about once a week to top them up.
With a 20 HP engine and very minimal hotel loads, they don't work hard
anyway. I'm just wondering how they would like being driven by the
low tech Hitachi alternator with its tiny built in regulator if I had
occasion to motor for 12 - 25 hours straight to move the boat
somewhere.

--

Roger Long

I know this is a serious question and I'm not trying to be a PIA. From
model T's to inverters in one fell swoop. Model T's were hand cranked,
used a spark coil and a magneto (I think).
There was no battery, heater or fuel pump. Basic in black. All in fun
boys

Hey!

Don't you know it is a material violation of usenet rules to post real
facts!

Actually, the T's did have dry cell batteries to aid in generating a
healthy spark while hand-cranking.

But you are dead on in saying that they had no alternators or generators.

Thanks!

Chuck

wrote:
I know this is a serious question and I'm not trying to be a PIA. From
model T's to inverters in one fell swoop. Model T's were hand cranked,
used a spark coil and a magneto (I think).
There was no battery, heater or fuel pump. Basic in black. All in fun
boys

On Sat, 11 Mar 2006 17:20:55 GMT, in message

"Roger Long" wrote:

BTW my AGM's are working great the way I am using them, short motoring
periods and an overnight plug in about once a week to top them up.
With a 20 HP engine and very minimal hotel loads, they don't work hard
anyway. I'm just wondering how they would like being driven by the
low tech Hitachi alternator with its tiny built in regulator if I had
occasion to motor for 12 - 25 hours straight to move the boat
somewhere.

If your concern is over-charging from extended motoring, how about
adding a high current draw accessory that you can turn on whenever you
don't want those amps flowing into your batteries? Just a thought...
I'm sure I can find a way to burn plenty of amps, at least in terms of
the output of a cheap little alternator.

Or read the manufacturer's specs on the AGMs to find out what their
acceptable max continuous charging voltage is and make sure your
regulator doesn't exceed that.

The "Model T" alternator I used to have on my engine (A4) was
regulated to a voltage low enough that it never really fully charged
the batteries, so I could run the engine forever... Sort of the
opposite problem to what you are imagining. I only got full charge
when I got the chance to plug in overnight. You may be in the same
situation.

I would suggest that you partially discharge the batteries, start the
engine, then go for an extended motor cruise. Monitor the voltage
across the batteries and see where it stabilizes. Then make the
assessment about whether or not extended motoring will hurt your
batteries.

Ryk

On Sat, 11 Mar 2006 13:56:14 GMT, "Roger Long"
wrote:

However, why not disconnect the alternator from the battery circuit
and run it to an inverter large enough to run the dual 10 amp battery
charger?

The alternator needs to always have a load on the output to keep the
voltage from going too high and burning out the diodes (integral to
the alternator). Normally the battery provides this constant load.
The risk is that your inverter might have a mode where it turns off in
some way, leaving the alternator unloaded, and leaving you looking for
a replacement. I'd leave the battery in the circuit, why take a
chance?

"Wayne.B" wrote

a replacement. I'd leave the battery in the circuit, why take a
chance?


Oh, I have no plans to actually do this. It's just a conceptual idea
I'm throwing out. The whole thing would have to be carefully
designed.

There is a gadget called, I think, a "Zapstopper" to protect the
alternator diodes if your wife's cousin turns the battery switch to
off when you ask him shut off the cabin lights. Something like that
might take care of the concern you raise though.

--

Roger Long

Hey Wayne,, that is what I was thinking but since I am too dumb to figure
this stuff out; I left it up to you.

Once, long ago, in another time, before ... anyway,, I had a boat with the
switch. The 3 way switch that you could set for battery 1, 2, or both.
Nobody told me and I was young and dumb so I decided to show off for my crew
by switching the knob.

"Look, now I am recharging both and now I am charging one"

Next day,, no alternator.

Live and learn..

JW

--
"Wayne.B" wrote in message
...
On Sat, 11 Mar 2006 13:56:14 GMT, "Roger Long"
wrote:

However, why not disconnect the alternator from the battery circuit
and run it to an inverter large enough to run the dual 10 amp battery
charger?

The alternator needs to always have a load on the output to keep the
voltage from going too high and burning out the diodes (integral to
the alternator). Normally the battery provides this constant load.
The risk is that your inverter might have a mode where it turns off in
some way, leaving the alternator unloaded, and leaving you looking for
a replacement. I'd leave the battery in the circuit, why take a
chance?

On Sun, 12 Mar 2006 12:23:55 GMT, "Thomas Wentworth"
wrote:

Once, long ago, in another time, before ... anyway,, I had a boat with the
switch. The 3 way switch that you could set for battery 1, 2, or both.
Nobody told me and I was young and dumb so I decided to show off for my crew
by switching the knob.

"Look, now I am recharging both and now I am charging one"

Next day,, no alternator.

Live and learn..

Oh yes. I think just about everyone with a boat has had that happen
at one time or another.

It has become my rule that the battery switch is never operated with
the engines running. Period. Doesn't matter if the switch is
"make-before-break", has a field disconnect wire, or there is a
"Zap-stopper" installed. There's always a possibility of failure and
it only takes a few microseconds to zap the diodes and ruin your next
couple of days locating and installing a replacement.