Using below battery volts

[nothing to lose]

 What do we do with power at 10V from a genny on a 12V system or 20V on a 24V system Etc..?

 Why waste it if you get enough to use. Every system is different but heres an idea to use it if you have low volts often enough. For big systems this may not work well or need modified, for small or medium size it should work well, and great for small hobby or experiment size.

 Maybe something like this been suggested before?

 Basically just run some small devices that work at random volts directly from the genny. Adjust as needed for your systems volt/amp outputs.

When I fly a low power wind genny or at times of low winds for long periods I will connect a 12V fan direct to the wind genny DC lines without batteries. When the wind blows the fan runs, slow at low volts and faster at higher volts.

I don't remember for sure the numbers on fans volts, amps, watts for various fans. I think some of mine start up around 2V or a bit more actaully. Don't remember on computer fans and I have various sizes and types so that could vary also which ones tested.

 I am sure the car type about 6" ones startup about 2V, those $8-$10 ones that plug into the cigarette lighter socket. I have a few of those types and often wire one or more directly to the wind gennies DC, no battieres, when I fly a low power genny or low winds for lond periods. It's neat to look at the fan and tell what the genny is doing. If fan barely turns I am getting low volts but the genny is turning. Fan revs up when wind gets the genny running good and I am getting more volts from it. As long as the genny cannot over power it and fry the fan it works good for me. I don't know what volts it would take to fry one of the auto type, I haven't yet. When the fan sounds like a jet I have put about 20V to it for short periods just fine.

I have fried computer types though. I'll be trying some auto radiator fans this year, try to get away from all the 120Vac fans I use now.

 It's like a part time fan only working when the wind is blowing, but no real losses. Actually since it runs far below battery charging volts I use allot of power I would not have got if just charging. Of course at startup volts around 2V it's not turning fast enough to really do much, about 6V is nice. I think once it gets started about 2V it still turns down to about 1V or 1.5V. For an extra fan for random use just to move more air when it works I like it. It does not use any power when wind is not blowing, it just doesn't run.

 I sometimes use a car type 12V relay with a fan like this.

 When the genny puts out enough volts the relay triggers and batteries charge plus hold the volts down to 12V so fan does not over power and fry. Using a resistor or such so that the relay triggers about 14v the fan would run full speed still from the genny power while batteries charge. Anytime there is 2V but less than 14V comming from the genny then the fan would run using what power it can get.  So basically 10V from any genny gets used even though it's below charging volts so it's not wasted. I need the fans anyway! Also the fan is not draining batteries when power is not being made to charge them, the relay cuts out the batteries when below 14V or so. Since I always have fans running  anyway this works very well having the extra ones whenever they do run. I am either moving hot air or cool air with fans all year.

 I can think of allot of uses for this. Venting a moist area like a crawl space, just move extra air in a hot house, venting a shed, reducing heat in a motorhome in summer, etc.. Stuff the fan would be good for but not required all the time.

Many items other than fans could be used same way. Maybe small lights for low heat?

For a small wind genny on a motorhome for example, durring summer use that below charging volt power to run a vent fan to get rid of excess heat anytime 2V-10V is being made, no drain on batteries when no wind. That could make a much cooler camper when you come back at night and save power later when you actaully need to cool it.

 Durring winter maybe use lights or such to heat a small tank of water anytime low volts are available, not alot of heat maybe but a few degrees warmer could save on other heating a bit. Small light under a brooder could keep baby chicks warm and prevent main heater from turning on as often, save other power?

I mostly do this with small 12V gennies, but it could be done with any setup just change to your system requirements, 24V 48V, etc..

For those projects that do not turn out just right, use that 8-10V max same way. I did that too.

 I have found I have allot of power at times to be used direct like this that is below charging volts, and that saves me battery power later.

[Ding123]

It sounds really neat! I used to do the same sort of thing but I found it was harder to get the gen up to cut-in in speed.

If you find time,maybe you could show a rough sketch of how you hooked your 12 volt relay up.Thanks.

Good Stuff!!!

[Capt Slog]

I've been thinking about this one too.  It seems a shame to be loosing the power at those times when it's turning but not upto cut-in speed. For me this is going to be LOTS of the time.

I was thinking it would be nice to charge Ni-cads at the lower revs,sure that there is some circuitry alrady out there which manages it with solid state.  I can foresee problems with the range it would have to handle though.

[asheets]

Lately, I've been playing with adjustable DC to DC converters that always hold the output at charging voltage no matter what the input.  You lose amps and efficiency when the input voltage is too low, but it is better than wasting it all.

Poster "Amanda" has talked about several circuits here.  Recently, I've also been playing with this circuit -- http://www.talkingelectronics.com/Projects/SolarCharger/SolarCharger.html .

[ghurd]

Thanks, I have been looking for that link for a couple years. Lost it somewhere along the line. Figured they went under.

Maybe for 18V drill batteries from small 12V solar, 12 and 14.4V batteries from cheap yard light PVs, etc.

Post how that circuit works out for you!

G-

[nothing to lose]

The relays I use are normally simple 12V relays found in many cars (free or cheap used), 4 legs.

 2 legs will close the contacts connect + - to those, contacts close about 12V and open about 8V, relay uses very little power itself. A resistor can be used to raise the volts required to close contacts, adjust resistor value as wanted to close at 13V-14V open at 9v-10V?

Other 2 legs are to the contacts, genny in one leg and out to battery post with other leg. Other battery post connects to genny as normal. Probably to a bridge rectifier or if a DC motor a diode and motor wire.

Put a Diode on a battery wire so power flows into battery but not back into circuit, that prevents the battery volts from holding the contacts closed or powering the fan when the genny volts drop. Without a diode you would back feed the relay and fan, only thing that would happen is the battery would run the fan and keep the relay closed when genny is not running.

Treadmill/Ametek type PM DC motors you want a diode in the battery line to prevent back feed to motor/relay/fan and tap into genny line between the diode and genny for the line to relay and low volt load. If you have an DC output from the motor your fine, if AC output you want diode on the line going to the relay and low volt load also.

It might take a little longer or a bit more wind to reach charge voltage as you said, I never noticed it really myself and alot could depend on the low volt load used. A normal lightbulb would hold it back more than a fan I think. But the main idea is to use that low volt power for something usable really when you have it but not charging volts. So if for 12hrs a day you get 10V from the winds and only 4 hours of charging volts during the day, that 10V is good to be using as made instead of loosing it.

Right now I been watching my winds and a genny for awhile. On average I get strong winds a few hours morning and night, durring the warmer sunny day when heat is building up I get very little wind. I can run small fans with that wind at low volts but not charging batteries with it. So when I need fans most I would have to use battery power or grid to run them and loose the low volts made, or I can use the low volts for a steady small breeze and save batteries for later. Right now cool enough here not to worry about it, though today is getting warm in here so it won't be long.

 I been charging 80V-100V small banks low amps, 180V open circuit with a genny in good winds, but durring the day (like right now) I am not getting enough wind to have 48V open circuit. A good small/medium 12V might be making 6-10V for a few hours or even most the day, and that would help cool the house if needed.

 I don't have a meter handy but I have a fan running direct from a small genny now just to circulate the air, and it's running at maybe 6-8V geussing by speed right now. Sometimes not running at all and never fast enough to be at 12v or above since about 7am (5-6 hours).

[Ungrounded Lightning Rod]

Lift-type blades lose efficiency drastically when their speed is held down by drag.  Devices that attempt to use power when the wind is low must be careful not to overload them.  Otherwise they could be held in stall in winds well above those that would take them to normal cutin.

When the wind is low there is very little power to be had.  If there is a significant amount - say because the cutin had been set high to keep efficiency high in typical wind speeds on a magneto/diode/stray-resistance/no-electronics rig - an appropriate solution might be rewinding or reconnecting the mill for lower cutin and using a max power point controller to, not just get the most out of the mill, but also down-convert the voltage, up-converting the current.

Such a device would have a complexity approximating that of the "salvage the below-cutin power for small loads but don't stall the mill" device, and would solve the real problem, by squeezing every watthour possible out of the turbine and into the batteries.  (It would also let you run the mill at higher voltage and thus reduce your wiring losses.)

[Bruce S]

G-

   I thought enough to purchase the "kit". don't bother IMHO.

circuit PCB doesn't have correct holes for most of the parts. Wire was not enough close to being correct length, and no emails requesting shipping or Kit problem was ever answered.

Plus it took the kit 2 weeks coming snail mail and also had to pay extra for shipping and VAT coming from Australia.

Bruce S

concept is sound, but I was so shocked at how bad their service is/was I didn't even try putting it together.

My bad for not finishing the kit on perf board, but a kit means ....

[ghurd]

I think I sent email a couple / few years ago regarding the circuit, S&H to USA, etc.

Answer was something like "its probably posted online- somewhere".  Good chance I ordered one and never got it.

The 2 weeks I could handle, crappy custom PCBs I cannot (you knew that).

A kit IS supposed to be a kit.

Maybe this outfit is a candidate for TomW's list?

[asheets]

Gosh, I hope this isn't as bad as everybody is making it out to be -- I just ordered a kit because my homebrew versions were acting kinda strange...

[s4w2099]

Why not use a boost converter to pump up the voltage and actually charge the batteries? :-|

[Bruce S]

Alan;

   You may have better luck than I did.

Check the larger wire and make sure it is the correct length and make sure the PCB has holes correctly sized to allow you to put the parts in them. Pay close attention to the blocking diode, the board I have is 1/2 the correct size needed. I have since pulled mine out and will gather up my own wire to do this. I have no where near enough length from the one they sent to get 45 turns out of it.

Let us know how it does.

I have some older small broken lawn lights that I would like to use these on too.

Cheers

Bruce S

 

[Bruce S]

Yep, this is pretty much what this is for. It takes to lower voltages and pulls them up to charging levels. It's good for using when the winds or small rescued lawn lights aren't enough to start cut in for large sized batteries , but can surely charge a small bank of AA's or AAA's .

This unit makes use of the interaction of coiled wire as a step up volatge.

Hope this helps;

Bruce S

[shmuu102]

what about gerating hydrogen (brown gas) to be used to run a generator in times of need..

i am working on a system to use a hydrogen generator cell  durring undervoltage and as a power soak in high wind.  Think of how much energy is waisted in power soaks and furrling your genny out of the wind.

[Bruce S]

shmuu102;

  This leads itself to other directions.

strickly speaking, if you use the extra or under power to store or as a dump load , then yes it makes sense to me to use it for this.

Brown's gas is something that has been in question for a long time. A lot of studies have been made and both sides claim victory. The possible problems I see with producing Brown's gas is its inherent danger and low power band.

Hydrogen is dangerous enough, Brown's gas is even more so due to it's very nature of not being pure H2.

Storing the under power in let's say old car batteries to use for electrolsys is a good why to keep the old car batteries from wasteing away somewhere where's there's no recycling program.

H2 & Brown's takes a bunch to power gens. You could also use this extra stored power to run small heaters to distill Alky to run in petrol powered gennies, or to keep methane producers warm. Much less dangerous.

The main though for this post was to make use of those less-then optimum solar days or when Murphy comes to visit when putting up a 'mill.

However, no to discourge you from trying as with the proper safety precautions this is possible. The danger in these gasses are for more than just your surroundings H2 will reach out and touch others if not careful

Becarefull!! and have fun

Bruce S

 

[craig110]

Perhaps others who are more knowledgable on this will chime in (I'm a solar panel person), but my understanding of furling is to keep the generator from producing so many amps that it cooks itself and it doesn't matter what is using the power.

[RP]

Also to reduce the effective frontal area to the wind to prevent catastrophic unplanned disassembly of the tower.