Battery voltage? Blow inverter?

[dblais]

I have this generator:
2 stators
20 poles  (1" round magnet 3/8  *40)
15 coils of 67 turn
AWG 17
At 230 RPM i get more then 30 volt (no load).

First question:
Want i understood after all my reading is I can put 20,30,50 volt output into my 12 volt battery, until the battery get full charged. After it get full charged i need to load the battery (dump load) to be sure that i don't overcharge the battery . But When my generator is off, i read 12.2 volt on my battery. When the generator is on i read 21.7 volt (but my battery get like 5 amp)... So how can i know the true voltage of the battery? I can't disconnect the generator each time...


Second question:
If i put a inverter on my battery, and my generator is ON then more the 21.7 volt will go inside the inverter and it will blow?
If i use a dump load to reduce the 21.7 volt to 14.1 volt. Then it's mean that I loose electricity (inefficient) and my battery only get like .5 amp?!


Thank you!
David

[Bruce S]

need a bit more info to really help out.
What type of battery ? Flooded? SLA? NiCd? NiFe?
standing voltage? 12V, 24V? and  the Ahr rating?

what voltage is the inverter rated for 12V, 24V, ? this is important.
General answers:
bad idea to hook those voltages up to ANY 12V rated battery from a genset. Sure it will pull the gen voltage down to the battery voltage BUT will begin to quickly cook the 12V battery. AND the standing voltage of this one seems that way already.
Inverter will blow ->>> YES

Bruce S

[dblais]

Right now I'm looking for information to make my choice.

For my test i will probably use a 12 volt car system, witch is not recommended... Later i will buy Deep-cycle lead-acid.

I don't have the inverter right now. I want to know everything before. If I don't use a inverter and i use only light that work with 12v (connected to the battery), there is no (easy) way to separate the 14.4v of the battery from the 18 volt of the generator that charge the battery? Because my light can blow or flash each time the RPM change...

I think i will do this electronic board (piclog) as controller: http://www.thebackshed.com/windmill/PicLog2.asp

David

[ghurd]

The battery is too little to do any testing.
G-

[wpowokal]

To elaborate a little on super hero G's advice, a single 12V battery can not absorb the current your wind generator can deliver, that is why the terminal (battery terminal and wind turbine output) voltage rises so high.

 If the battery was large enough in amp hours it would clamp the voltage until it was fully charged, say 15V, you are not actually getting the elevated voltage into your battery because it can not absorb so much current, even if it was deep cycle it still could not absorbe that amount of current.

So how much can a battery absorb, well a good rule of thumb is 10% of rated amp hour initially, tapering off as the state of charge rises, why 10% well another factor needs to be taken into account when charging batteries and that is temperature, elevated charge currents cause heating (by the chemical reaction) and can/will damage your battery.

http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery

David you are asking the right question so just keep asking until you have a grasp of the situation.
allan
 

[dblais]

The battery is too little to do any testing.
G-

This answer does not help me a lot... Can you give more explanation? I have a small creek of 300watt and I can use wind. I don't need to have a large battery bank. I go to my cottage only 1 day each 7 day.

I'm just looking how to put this variable energy into my battery to light something or plug a small inverter... This is why i was asking my 2 question.

Question 1:
how can i know the true voltage of the battery?  Because when the generator is on or off the voltage of the battery is not 1the same.

Question 2:
If i put a inverter on my battery, and my generator is ON then more the 21.7 volt will go inside the inverter and it will blow?
Answer:
Yes it will blow. So i need to find a mechanic or electronic way to stabilize the voltage or to buy a inverter that can have a large input rangem witch is rare and $$.

Thank you!
David

[dblais]

To elaborate a little on super hero G's advice, a single 12V battery can not absorb the current your wind generator can deliver, that is why the terminal (battery terminal and wind turbine output) voltage rises so high.

 If the battery was large enough in amp hours it would clamp the voltage until it was fully charged, say 15V, you are not actually getting the elevated voltage into your battery because it can not absorb so much current, even if it was deep cycle it still could not absorbe that amount of current.

So how much can a battery absorb, well a good rule of thumb is 10% of rated amp hour initially, tapering off as the state of charge rises, why 10% well another factor needs to be taken into account when charging batteries and that is temperature, elevated charge currents cause heating (by the chemical reaction) and can/will damage your battery.

http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery

David you are asking the right question so just keep asking until you have a grasp of the situation.
allan
 

Thank you wpowokal! Now i understand why my voltage was going very high...  So if i use only one battery i dont really have the choice to charge slowly at 14.4v.  So my generator is too "powerfull" for one battery at 280 RPM...


*Sorry if i'm not always clear and i'm not fast to understand. It's because i speak french and i try write and read in english!


David

[wpowokal]

David if your power requirements are small the your 300 Watt water turbine could provide this direct, there are ways to set up a water turbine that dumps any power (to heating elements mostly) that you don't use, therefore no need for batteries or inverter. Or you could use a voltage regulated generator, which would supply up to 300 watts as much current as you need.

Ok you slipped in a reply on me, the only fact I know about French is they can not drive, I know that after one French back packer crashed one of my utes, all of which is by the by.

You can use a dump load to bleed any excess current away from your batteries so they/it see a safe voltage, actually this is quite an essential part of any system, actually super hero plus G can supply you with one, click on his link at the bottom of his post, he is actually a cleaver guy, I was also going to also say nice but........... 

Your wind turbine may or may not be too powerful, but one thing is certain if your site is unattended you will need a dump load or you will ruin your battery. For what you describe I would not be using a wind turbine as it's output would be considerably wasted. A much more eloquent way would be a small battery and solar panel/s very easy to control.

allan

[dblais]

David if your power requirements are small the your 300 Watt water turbine could provide this direct, there are ways to set up a water turbine that dumps any power (to heating elements mostly) that you don't use, therefore no need for batteries or inverter. Or you could use a voltage regulated generator, which would supply up to 300 watts as much current as you need.

Ok you slipped in a reply on me, the only fact I know about French is they can not drive, I know that after one French back packer crashed one of my utes, all of which is by the by.

You can use a dump load to bleed any excess current away from your batteries so they/it see a safe voltage, actually this is quite an essential part of any system, actually super hero plus G can supply you with one, click on his link at the bottom of his post, he is actually a cleaver guy, I was also going to also say nice but........... 

Your wind turbine may or may not be too powerful, but one thing is certain if your site is unattended you will need a dump load or you will ruin your battery. For what you describe I would not be using a wind turbine as it's output would be considerably wasted. A much more eloquent way would be a small battery and solar panel/s very easy to control.

allan

Yha solar is simpler to control but you can't DIY... So I did a axial flux generator, for fun. And i want use it...

When my battery is a 12.2 volt and i turn on the generator i get 21.7 volt, so this mean that my battery bank is too small and i need to dump the load until i get 14.4 volt ? It's like to say i wast energy because my battery bank is too small?

David

[ghurd]

I meant the battery is too little to do any testing.

Pushing 5A into a 12.2V battery that rises to 22V means the battery is Very Tiny.
Or the battery is faulty.  
Or both.  I have a feeling it is a very small faulty battery.

300W.  Is that the calculated electrical output, or power in the water before losses?
300W of electrical power in a 12V system is about 22A.  That is a lot of power per day.

I agree with Allan's battery estimate.  220AH would be Great.  That is a pair of 6V deep cycle "golf cart" batteries in series.
The battery bank (with good batteries, Not two 110AH boat batteries) would allow operation of a small microwave, a large TV, etc.

With no battery, being limited to 300W peak power would be frustrating to me.
Given the total costs involved, I would at least have a 110AH deep cycle boat battery in the system.  With a decent controller, it would spend most of the time at 14.4V, waiting to supply a surge to a larger load.

The hydro could be shut down when nobody is there.  6 days of wear and tear to heat dump resistors seems pointless.
A 10W solar panel can maintain the battery for those 6 days.

If you can get your car close to the generator test?
Start the car, turn on All the lights, and turn the heater fan on high.
Use the car battery for the test.  Connect the generator to the battery with heavy cable.
The battery will stay at about 14.2 ~ 14.4V, even when the generator is pushing 25A (>300W) amps into it.

G-

[wpowokal]

David firstly since you are only on site one day in seven then you must have automatic controls to protect your battery or shut down the wind turbine. yes you need a dump load, the power is only wasted if it can not be used, one factor for us living 24/7 off grid is load scheduling, meaning we use the renewable energy when it is coming in and conserve when it is not.

Your battery is there to supply power when there are no renewable supplies coming in, yes that point is a little bit of a guess unless you have reliable winds, so you will be "wasting" some or maybe lots of power but if you are not there to use it is it a waste? A battery bank that is larger than required is also a waste of your money (euros). How reliable are your winds? If I had a creek that was good for 300 watts 24/7 I would be doing cart wheels to said creek.

allan