Alternative Power sources - AutoStart - Shutdown Charger/Generator

Author

AutoStart - Shutdown Charger/Generator

grumtac@sbcglobal.net

2005-08-05, 1:21 am

Greetings,
I have a single battery on a trailer that I would like to find a way to
charge when it runs down. Cutting Grass one day, I started to think
about an older Lawn mower I had with a Vertical Shaft engine and a belt
drive "starter/generator" on it.

After a little research, I find out that the Generator part on most of
those puts out 15amps, with Golf Cart units up to 25 amps. So I easily
can envision that with a simple circuit even I could wing together,
this thing could autostart when the voltage drops to a certain point.
What I do not know how to do is build a circuit that can shut the thing
down when the time is right. Easiest for me would be a timer circuit,
but that would not be as accurate as something that monitored the
battery.

With all of you fellows who are familiar with proper charging
techniques, is it possible to build some sort of monitor circuit that
could ignore the fact that there would be a full 12v in the system the
minute it starts and runs, but charges or runs long enough to charge
things correctly and then shuts itself down ?

I would think that those 15 amp starter/generators wouldn't take much
more than one horse or so to pull, and I would like to have the
smallest most compact motor possible. However, today, there is not too
much on the shelf in a 4 stroke with an automatic choke under 4hp, so
that is what I would likely end up with.

Any pointers appreciated,

Grummy

Ron Rosenfeld

2005-08-05, 7:21 am

On 4 Aug 2005 20:23:03 -0700, grumtac@sbcglobal.net wrote:

>With all of you fellows who are familiar with proper charging
>techniques, is it possible to build some sort of monitor circuit that
>could ignore the fact that there would be a full 12v in the system the
>minute it starts and runs, but charges or runs long enough to charge
>things correctly and then shuts itself down ?

Depending on your battery, it won't be fully charged at 12V.

In my RE system, the generator autostarts after it has been at some low
voltage for some length of time (e.g. 11.8V for 2 hrs), runs until the
voltage reaches a certain level (e.g. 14.7V); maintains that voltage for a
few hours (for "absorption") and then shuts down.

-- ron (off the grid in Downeast Maine)

grumtac@sbcglobal.net

2005-08-05, 10:21 am

Ron Rosenfeld wrote:

> Depending on your battery, it won't be fully charged at 12V.

I should have indicated a higher voltage. I would assume that those
units do put out more than 12V. After all, those start on demand Golf
carts routinely deliver industrial type service. I will have to throw a
meter on one and see.

> In my RE system, the generator autostarts after it has been at some low
> voltage for some length of time (e.g. 11.8V for 2 hrs),

H'mmm. I could put a simple countdown timer into place to do that, but
a countdown timer wouldn't take into account any excessive draw on the
battery, unless of course I put another stage in that start logic. I
could make it absolutely start at a lower voltage yet than where the
countdown timer starts. I wonder why it waits for so long ?

> runs until the voltage reaches a certain level (e.g. 14.7V); maintains that voltage for a
> few hours (for "absorption") and then shuts down.

I'm thinking that this "absortion" is actually read or calculated from
somewhere rather than a timer function. My thoughts were something that
checks specific gravity or something ? Is there some kind of probe out
there that can go into a battery cell and be used for anything I am
trying to do ?

Thanks,

Grummy

Ron Rosenfeld

2005-08-06, 1:21 am

On 5 Aug 2005 05:31:47 -0700, grumtac@sbcglobal.net wrote:

>
>Ron Rosenfeld wrote:
>
>
>I should have indicated a higher voltage. I would assume that those
>units do put out more than 12V. After all, those start on demand Golf
>carts routinely deliver industrial type service. I will have to throw a
>meter on one and see.
>
>
>H'mmm. I could put a simple countdown timer into place to do that, but
>a countdown timer wouldn't take into account any excessive draw on the
>battery, unless of course I put another stage in that start logic. I
>could make it absolutely start at a lower voltage yet than where the
>countdown timer starts. I wonder why it waits for so long ?

My system actually has multiple parameters for starting the generator:

Below V1 for 24 hours or
below V2 for 2 hours or
below V3 for 15 minutes or
below V4 for 30 seconds or
Load current greater than X amps for Y minutes or
Generator has not run for Z days.

In almost five years, the starting (other than for the "not run" parameter)
has been due to either the V2 or V3 parameter. Depending on your set up,
you should be able to find a voltage/time combination or two that works for
your system.

>
>
>I'm thinking that this "absortion" is actually read or calculated from
>somewhere rather than a timer function. My thoughts were something that
>checks specific gravity or something ? Is there some kind of probe out
>there that can go into a battery cell and be used for anything I am
>trying to do ?

One issue is that the rate of charging to get from 80-85% state of charge
(SOC) to 100% SOC can be quite slow. You can boost the voltage and current
to allow higher levels, but if you do, you run the risk of permanent damage
to your batteries. It is a good idea to overcharge from time to time (this
is called equalization). But you have to monitor the battery temperature
and also ensure that you replace the water that will evaporate.

In my RE system, most of the energy comes from wind or PV. However, when I
run the generator, the settings that I use are designed to only bring the
batteries to about a 75% SOC. It's too inefficient to run a propane
generator to bring them to 100% SOC, so I ensure that the wind and PV do
that.

I know there are electronic specific gravity testers, but I believe they
are quite expensive. If you don't want to use time, and you are using a
voltage controlled charger, you could look at charging current, and stop
your generator when it reaches some level for some length of time.

-- ron (off the grid in Downeast Maine)

Ulysses

2005-08-06, 11:21 pm

<grumtac@sbcglobal.net> wrote in message
news:1123212183.290825.74120@o13g2000cwo.googlegroups.com...
> Greetings,
> I have a single battery on a trailer that I would like to find a way to
> charge when it runs down. Cutting Grass one day, I started to think
> about an older Lawn mower I had with a Vertical Shaft engine and a belt
> drive "starter/generator" on it.
>
> After a little research, I find out that the Generator part on most of
> those puts out 15amps, with Golf Cart units up to 25 amps. So I easily
> can envision that with a simple circuit even I could wing together,
> this thing could autostart when the voltage drops to a certain point.
> What I do not know how to do is build a circuit that can shut the thing
> down when the time is right. Easiest for me would be a timer circuit,
> but that would not be as accurate as something that monitored the
> battery.
>
> With all of you fellows who are familiar with proper charging
> techniques, is it possible to build some sort of monitor circuit that
> could ignore the fact that there would be a full 12v in the system the
> minute it starts and runs, but charges or runs long enough to charge
> things correctly and then shuts itself down ?
>
> I would think that those 15 amp starter/generators wouldn't take much
> more than one horse or so to pull, and I would like to have the
> smallest most compact motor possible. However, today, there is not too
> much on the shelf in a 4 stroke with an automatic choke under 4hp, so
> that is what I would likely end up with.
>
> Any pointers appreciated,
>
> Grummy
>

This is outside of my life's experiences (and I ain't young). You mean to
say you have a lawnmower with a belt-drive electric start that also doubles
as a generator? Sounds like what a lot of folks have been building from
scratch to charge batteries. Got any pictures of it?

Anyway, I would think a circuit that grounds the ignition when it gets to a
specific voltage would be simple to build but as Ron Rosenfeld pointed out
you would probably be better off with something that detects the charge rate
and slows down when it gets to somewhere around half of your maximum charge
rate. My experience tells me that an older battery might be fully charged
at a lower voltage than a newer battery and the charge rate on volts can
vary with the type of charger you are using. What I did to avoid all of
this figgering and wondering was to connect an engine driving an alternator
to a battery with an inverter and then I connected my Vector Smart Charger
and use it to do all the thinking for me. Sounds kinda redundant to use a
battery and an inverter to charge another battery but it works and it's
easy. Some day I'll figure out how to take the first battery out of the
system but when I tried it the voltage went to high and exploded an
inverter.

grumtac@sbcglobal.net

2005-08-07, 1:21 am

Ulysses wrote:
> This is outside of my life's experiences (and I ain't young). You mean to
> say you have a lawnmower with a belt-drive electric start that also doubles
> as a generator? Sounds like what a lot of folks have been building from
> scratch to charge batteries. Got any pictures of it?

You can find "starter generator" pictures on Ebay. Just search for the
words starter generator.

This setup had been very common on older Garden Tractors. It is less
common today, as most now use a traditional starter, and have a built
in Generator behind the flywheel. A lot of those only put out 10 amps,
and this is only on motors maybe starting at 10hp. I bet if you take a
drive by any lawn aand garden place that has a "line up" of older
stuff, you will see one with it. Both the larger tractors with
horizontal shaft and smaller ones with vertical shaft can be found. I
prefer to use a vertical shaft as they are generally cheaper, and would
fit in my application better. I also would have both electric and pull
start just in case.

I would think one of these starter generators could charge fine with
even a 1hp motor. Lots of 6HP tractors were made in the 70's.... you
surely used at least 5HP for moving and cutting with a 30" deck. (Wish
I could find a one horse power twin!!)

> What I did to avoid all of this figgering and wondering was to connect an engine >driving an alternator to a battery with an inverter and then I connected my Vector >Smart Charger and use it to do all the thinking for me. Sounds kinda redundant to >us
e a battery and an inverter to charge another battery.......

Yep, I figure that redundant too. I would think that we live in an age
where one of these starter generators could be connected to a circuitry
to make this happen. Now we have automatic Choke motors that work
pretty well.

There are a LOT of applications where this would be slick. The
"startup" routine, even with that nice 2nd writeup described by Ron,
should be rather easy. The proper charge time or cycle is the tuff one.
I think I will throw something together and just try it with generic
timers. We'll see what we get.

Grummy

Ulysses

2005-08-08, 4:21 pm

<grumtac@sbcglobal.net> wrote in message
news:1123388057.737629.285870@g47g2000cwa.googlegroups.com...
>
> Ulysses wrote:
to[color=darkred]
doubles[color=darkred]
>
> You can find "starter generator" pictures on Ebay. Just search for the
> words starter generator.
>
> This setup had been very common on older Garden Tractors. It is less
> common today, as most now use a traditional starter, and have a built
> in Generator behind the flywheel. A lot of those only put out 10 amps,
> and this is only on motors maybe starting at 10hp. I bet if you take a
> drive by any lawn aand garden place that has a "line up" of older
> stuff, you will see one with it. Both the larger tractors with
> horizontal shaft and smaller ones with vertical shaft can be found. I
> prefer to use a vertical shaft as they are generally cheaper, and would
> fit in my application better. I also would have both electric and pull
> start just in case.
>
> I would think one of these starter generators could charge fine with
> even a 1hp motor. Lots of 6HP tractors were made in the 70's.... you
> surely used at least 5HP for moving and cutting with a 30" deck. (Wish
> I could find a one horse power twin!!)
>
an engine >driving an alternator to a battery with an inverter and then I
connected my Vector >Smart Charger and use it to do all the thinking for me.
Sounds kinda redundant to >use a battery and an inverter to charge another
battery.......[color=darkred]
>
> Yep, I figure that redundant too. I would think that we live in an age
> where one of these starter generators could be connected to a circuitry
> to make this happen. Now we have automatic Choke motors that work
> pretty well.
>
> There are a LOT of applications where this would be slick. The
> "startup" routine, even with that nice 2nd writeup described by Ron,
> should be rather easy. The proper charge time or cycle is the tuff one.
> I think I will throw something together and just try it with generic
> timers. We'll see what we get.
>
> Grummy
>

I was using my engine driven alternator to charge my trailer batteries (two
220 Ah 6 volt in series) but I was concerned because it seemed to be
charging at too high of a current rate and too low of a voltage. I suspect
charging this way occasionally would be OK but might cause too much sulfide
build-up if done regularly. By having it connected to an inverter it also
works as an 800 watt generator and since I already had the Smart Charger
this way works well for me. I have a small alternator on a boat motor that
I'm thinking about playing around with for a direct charger. It might only
take 1-2 HP to get it to charge batteries.

grumtac@sbcglobal.net

2005-08-08, 7:21 pm

Ulysses wrote:

> I was using my engine driven alternator to charge my trailer batteries (two
> 220 Ah 6 volt in series) but I was concerned because it seemed to be
> charging at too high of a current rate and too low of a voltage.

I hoped to avoid concerns about that to some extent, after all, a
Garden Tractor, or at least all that I have owned (and I have owned
many!) go thru all kinds of Various cycles.
I used some for landscaping work which was often start and stop work.
Never really had any battery failures or undue generator issues. These
use an external regulator.... I wonder if one of the older adjustable
regulators could be used on it ? H'mmm..

>I have a small alternator on a boat motor that I'm thinking about playing around with for a >direct charger. It might only take 1-2 HP to get it to charge batteries.

I never thought about a Boat motor for that.....They do have plenty of
2 cylinder unit available, tat is a plus.

Is Yours an Aircooled unit ? a 2 or 4 Stroker ?
I figure if there was a small four stroke boat motor that had at least
15 amps of output, it might be worth the time to deal with the water
cooling issues.... Slightly more weight, but less noise..... Time to
hit the books !

Thanks for giving me more to think about !

Grummy

Ulysses

2005-08-09, 1:21 am

<grumtac@sbcglobal.net> wrote in message
news:1123538425.055015.231080@o13g2000cwo.googlegroups.com...
>
> Ulysses wrote:
>
(two[color=darkred]
>
> I hoped to avoid concerns about that to some extent, after all, a
> Garden Tractor, or at least all that I have owned (and I have owned
> many!) go thru all kinds of Various cycles.
> I used some for landscaping work which was often start and stop work.
> Never really had any battery failures or undue generator issues. These
> use an external regulator.... I wonder if one of the older adjustable
> regulators could be used on it ? H'mmm..
>
around with for a >direct charger. It might only take 1-2 HP to get it to
charge batteries.[color=darkred]
>
> I never thought about a Boat motor for that.....They do have plenty of
> 2 cylinder unit available, tat is a plus.
>
> Is Yours an Aircooled unit ? a 2 or 4 Stroker ?

I was refering to a Mercury 1500 which has an alternator that can be
removed, much like a car alternator, just smaller, and running from a small
engine via a belt. I do, however, have a 7 HP outboard which I dismissed as
a useful engine for driving an alternator on the grounds that it is a 2
stroke and is both air cooled AND water cooled. It would require a constant
water supply which would really complicate things.

> I figure if there was a small four stroke boat motor that had at least
> 15 amps of output, it might be worth the time to deal with the water
> cooling issues.... Slightly more weight, but less noise..... Time to
> hit the books !
>
> Thanks for giving me more to think about !
>
> Grummy
>

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