micro hydro load controller

[andy baxter]

Hello,

I'm volunteering at a place out in the country who are living off the
grid. They already have a couple of windmills, which have been installed
professionally. They are also working on a micro hydro system. This has
been designed and partly built by a professional engineer during his spare
time, but he has been unable to do any more work on it for some time (at
least a year) due to other commitments. The turbine and alternator are
finished, but none of the rest of the electrics, including the charge
controller for the batteries (it's going to be a DC system with an
inverter).

They have just got hold of a battery backup system of the kind which is
used to supply emergency power to alarm systems, emergency lighting etc.
(I think it used to run the emergency lighting for a nursing home). This
is designed to charge some 12V batteries from the 240V mains, and there is
also a separate inverter which supplies mains power from the batteries.

I was talking to one of the people there, and he was talking about using
the battery backup system as a charge controller for the water turbine. I
was advising him to be cautious, for the following reasons:

- you need to have some way of shunting power to a dump load when the
batteries are fully charged and no current is being drawn, otherwise the
alternator may burn out.

- The charger is as far as can tell (I may be wrong here though)
a standard linear regulator, which I am not sure is suitable for this kind
of application where the input voltage may be variable. I would have
thought that a switch mode regulator would be more suitable, as these can
deal with a wider range of input voltages. I think this is not so much an
issue as with wind power, since the speed of the turbine and hence the
output voltage is probably fairly constant, so should be tunable to
whatever voltage is required.

Do either of these things matter as much as I thought, or am I being too
cautious?

Any advice appreciated, particularly from anyone who has any practical
experience with micro hydro or windpower electrics.

 

[jasen]

professionally. They are also working on a micro hydro system. This has
been designed and partly built by a professional engineer during his spare
time, but he has been unable to do any more work on it for some time (at
least a year) due to other commitments. The turbine and alternator are
finished, but none of the rest of the electrics, including the charge
controller for the batteries (it's going to be a DC system with an
inverter).

this altenator is it permanent magnet (like recyclesd smart-drive motor)
or electromagnet (like automotice altenator) based?

They have just got hold of a battery backup system of the kind which is
used to supply emergency power to alarm systems, emergency lighting etc.
(I think it used to run the emergency lighting for a nursing home). This
is designed to charge some 12V batteries from the 240V mains, and there is
also a separate inverter which supplies mains power from the batteries.

I was talking to one of the people there, and he was talking about using
the battery backup system as a charge controller for the water turbine. I
was advising him to be cautious, for the following reasons:

seems kind of ass-backwards to me unless he's planning on modifying the
charge controller.

- you need to have some way of shunting power to a dump load when the
batteries are fully charged and no current is being drawn, otherwise the
alternator may burn out.

ideally you'd want to turn the water off.

otherwise if you disconnect the altenator's output from no current will flow
and it won't heat up.

- The charger is as far as can tell (I may be wrong here though)
a standard linear regulator, which I am not sure is suitable for this kind
of application where the input voltage may be variable. I would have
thought that a switch mode regulator would be more suitable, as these can
deal with a wider range of input voltages. I think this is not so much an
issue as with wind power, since the speed of the turbine and hence the
output voltage is probably fairly constant, so should be tunable to
whatever voltage is required.

it really depends on the altenator they have.

 

[kell]

Hello,

I'm volunteering at a place out in the country who are living off the
grid. They already have a couple of windmills, which have been installed
professionally. They are also working on a micro hydro system. This has
been designed and partly built by a professional engineer during his spare
time, but he has been unable to do any more work on it for some time (at
least a year) due to other commitments. The turbine and alternator are
finished, but none of the rest of the electrics, including the charge
controller for the batteries (it's going to be a DC system with an
inverter).

They have just got hold of a battery backup system of the kind which is
used to supply emergency power to alarm systems, emergency lighting etc.
(I think it used to run the emergency lighting for a nursing home). This
is designed to charge some 12V batteries from the 240V mains, and there is
also a separate inverter which supplies mains power from the batteries.

I was talking to one of the people there, and he was talking about using
the battery backup system as a charge controller for the water turbine. I
was advising him to be cautious, for the following reasons:

- you need to have some way of shunting power to a dump load when the
batteries are fully charged and no current is being drawn, otherwise the
alternator may burn out.

- The charger is as far as can tell (I may be wrong here though)
a standard linear regulator, which I am not sure is suitable for this kind
of application where the input voltage may be variable. I would have
thought that a switch mode regulator would be more suitable, as these can
deal with a wider range of input voltages. I think this is not so much an
issue as with wind power, since the speed of the turbine and hence the
output voltage is probably fairly constant, so should be tunable to
whatever voltage is required.

Do either of these things matter as much as I thought, or am I being too
cautious?

Any advice appreciated, particularly from anyone who has any practical
experience with micro hydro or windpower electrics.

Best place for advice on this stuff:
www.fieldlines.com
My thought: hydro might not need a dump load because you don't have to
worry about the hydro overspinning and destroying itself the way a
windmill would. But take the foregoing with a grain of salt and get
some advice from the more experienced.

 

[Skipp says hello]

: - you need to have some way of shunting power to a dump load when the
: batteries are fully charged and no current is being drawn, otherwise the
: alternator may burn out.

Most often the alternator field potential is reduced in better systems.
Otherwise after battery equalizing (in better built systems) a shunt
type load diverter is used. Often you can use the extra power to move
vent air and heat or cool a building.

: - The charger is as far as can tell (I may be wrong here though)
: a standard linear regulator, which I am not sure is suitable for this kind
: of application where the input voltage may be variable. I would have
: thought that a switch mode regulator would be more suitable, as these can
: deal with a wider range of input voltages. I think this is not so much an
: issue as with wind power, since the speed of the turbine and hence the
: output voltage is probably fairly constant, so should be tunable to
: whatever voltage is required.

All depends on the potentials you're working with. If you're using lower
dc voltages to the battery bank... simply use one of the modern solar
charge controllers like something built by Trace (now Xantrex or something
like the Xantrex name).

: Do either of these things matter as much as I thought, or am I being too
: cautious?

Yes, if you want the system to work properly and last more than a few
months.

: Any advice appreciated, particularly from anyone who has any practical
: experience with micro hydro or windpower electrics.

I do both all the time but don't often get on this group anymore. You can
contact me direct through the below web page email contact icon and I'll
try to provide help as time allows.

cheers,
skipp

www.radiowrench.com/sonic

 

[andy baxter]

Best place for advice on this stuff:
www.fieldlines.com

Thanks - I've reposted this there.

My thought: hydro might not need a dump load because you don't have to
worry about the hydro overspinning and destroying itself the way a
windmill would. But take the foregoing with a grain of salt and get
some advice from the more experienced.

I'm also not sure why people say you need a dump load. What I'm thinking
is if you have an alternator which generates its own power for the field
coils, then if it overspins the voltage on these coils could rise too
high, increasing the current to the point where they burn out. Is that the
problem or is it something else (mechanical failure?)

 

[Homer J Simpson]

I'm also not sure why people say you need a dump load. What I'm thinking
is if you have an alternator which generates its own power for the field
coils, then if it overspins the voltage on these coils could rise too
high, increasing the current to the point where they burn out. Is that the
problem or is it something else (mechanical failure?)

That makes no sense unless the alternator can be overspun by the turbine -
very unlikely. If it's an auto alternator it's designed for a wide range of
speeds.