Battery Charging by Wind Turbine

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Bricolo07
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Battery Charging by Wind Turbine




by Bricolo07 » 07/09/17, 22:39

Hello,

I have already created on this forum subjects on the self-construction of my wind turbine but there I want to stay more theoretical / academic, I have a lot of questions in particular on batteries and storage of electricity.

I have a 3m diameter wind turbine mounted 7m high, 2 DC electric motors of 100w are driven by chain report x6. The two motors have an anti-return diode so cannot be powered, at the bottom I have a DC / DC converter 24v-> 13.8V, connect to a lead gel battery

- Why should the battery be charged at once? There is a lot of gusty wind so for a few seconds the load cuts off, is that a problem?
- In light winds, the voltage only goes up to 13v but amperes enter the battery, does it damage it?
- The two motors that generate the current are the same, but does the fact that there are 2 hinder the converter or the battery?
- What happens if two identical batteries are connected in parallel but one of which has been used more than the other?

Thank you for your answers
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Re: Battery Charging by Wind Turbine




by izentrop » 07/09/17, 23:51

Hello,
No, it is not necessary to charge a lead battery in one go.
It does not support deep discharges or overloads.
For overloads
  • Do not exceed 1/10 of the current capacity, to ensure good longevity. For 200 W of maximum power, provide a 166 Ah battery (200/12 X 10) or provide a regulator.
  • Switch off the charge as soon as the battery has reached 13,8 V (depends on the type of battery)
And to avoid deep discharge, use should be cut to 11,5V for example.

Is the DC / DC converter really useful? because it may be unnecessary losses. What are the characteristics of generators (not motors)?
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Bricolo07
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Re: Battery Charging by Wind Turbine




by Bricolo07 » 08/09/17, 20:47

thank you for your comeback
Yes I think the dc / dc is useful because it accepts 20 to 30 v input and regulates the output at 13.8v, on the manual it is marked may be suitable for battery charging. Even full the battery can not exceed 13.8v and I put a 30v relay which directs the generator output to a resistor to prevent the wind turbine from racing when the battery is full.
- Normally when the battery is full and we maintain 13.8v at its terminals, the amps no longer come in? does it become floating?
- My concern is that if the charge stops every 3 min and starts again after a burst, does it hinder the battery?
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Re: Battery Charging by Wind Turbine




by chatelot16 » 09/09/17, 20:58

it does not bother the battery to be charged intermittently, it is only the total that counts ... provided not to exceed neither the maximum current nor the maximum voltage

the problem is that charging up to 13.8v does not really charge the battery to its maximum energy: for electric vehicles we prefer a charge cycle which goes up to a higher voltage, a well-determined time to charge well background ... with a fully variable charge depending on the wind or the sun we do not know how to make a very precise charge cycle so we are content with this limitation at 13.8v and we do not take advantage of the full capacity of the battery. but we don't overload it and give it a long lifespan

there must certainly exist intelligent charger capable of letting the tension rise a little higher than 13.8 when it is useful ... but I let you search ... I don't know any
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Re: Battery Charging by Wind Turbine




by izentrop » 10/09/17, 09:11

It is a small system, not exceeding the maximum current is easy.

With 200 W it must be around C / 10 from a 166 Ah battery, so no need for a current regulator, only a system which cuts the connection with the battery taking into account the end of charge threshold and possibly a switching on a brake resistor.
The threshold at the end of charging is effectively to be adjusted according to whether a maximum load or a maximum longevity is desired.

There is also no need for a DC / DC converter since even if the generator voltage reaches 30 V when empty, the battery will absorb all the current and its voltage will only rise according to its state of charge.

This kind of circuit does it all

Uhh! almost, it misses the cut of use to avoid deep discharge.
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Bricolo07
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Re: Battery Charging by Wind Turbine




by Bricolo07 » 10/09/17, 09:40

Hello,
Very very good remark from izentrop, in my tests I found that if we put a load (bulb or motor) on the wind output, it absorbs all the intensity without limit and the voltage does not manage to rise. On the other hand if we put a (capacitive) battery there it is different, before 11v the wind turbine will be coasting because no power will be absorbed (perfect this will allow it to take momentum). It will continue to absorb while regulating the voltage which will gradually rise, on the other hand the concern it happened at 14v, the battery is almost full and less ampere returns so the voltage can climb suddenly, it is at this time that the DC / DC (or another regulator) is essential.
Doesn't it consume more charge cycle?

I am reformulating my question of intermittent charging, is charging with a variable voltage not exceeding 13.8v a problem?
All the systems that I know (charger, alternator ....) maintain the voltage at 13.8v, no more no less.

Are you telling me that charging at 13.8v limits capacity but keeps life?
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Re: Battery Charging by Wind Turbine




by Bricolo07 » 10/09/17, 09:43

At the DC / DC range, I could put a splitter coupler with another empty battery, we charge the first and once it is full we charge the second to prevent the wind turbine from racing.
As there is no empty battery, the voltage regulates itself.
Does a DC / DC limit the performance?
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Re: Battery Charging by Wind Turbine




by chatelot16 » 10/09/17, 11:17

it all depends on what type of regulator at 13.8v

we think of the standard regulator, which reduces the current not to exceed 13.8v and lets the voltage rise in the wind turbine

there are also parallel regulators: when the voltage of 13.8v is reached it does not reduce the current in the wind turbine: on the contrary it wastes the current somewhere, and leaves less for the battery ... until you waste everything when the battery does not want any more current at all

this principle of parallel regulator is very good for wind turbines because it does not let it get carried away!

this regulator principle is not often used because it produces a waste of energy ... but for a wind turbine the inconvenience becomes an advantage

another advantage of the parallel regulator: there is no regulating element in series with the charging current: no loss of energy due to a voltage drop when the battery needs to be charged ... there is loss only when the battery is full

the circuit which wastes the current should not be directly in parallel on the battery, because it could discharge the battery even if there is no current produced by the wind turbine: we could think of a non-return diode, but that does a trick in series and an additional loss, while the wind turbine already contains a rectifier which does the anti return function

solution: put 2 rectifier: one for the battery and another for the regulator: it is thus on that the regulator can only waste the current of the wind turbine and never drain the battery

another interesting tip for high power: supplying the waster with an alternative: thyristors or triacs are cheaper than transistors
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Bricolo07
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Re: Battery Charging by Wind Turbine




by Bricolo07 » 10/09/17, 12:23

Thank you for these tips but what do you think of my last idea?
The optional DC / DC to see and put a separator coupler at the terminal of battery 1, when it is full it switches to battery 2.
The waste of which you spoke will be used to charge another battery, on the other hand to be careful when this one is full there will be problem.

I am using a 6-cylinder gel battery and I would not shoot it with an unstable charge, for the moment I am only in the test phase and I saw that it was advisable to charge it properly with a real charger all 10 wind loads to give him a bite of his abilities
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Re: Battery Charging by Wind Turbine




by izentrop » 10/09/17, 22:52

This model includes a brake, better that to tinker and put the second battery in // http://wellsee.cc/goods-220-WELLSEE+win ... 5+15A.html

Personally, I would do all the automation with an arduino and 2 power mosfets: one to switch the battery, the other for the brake resistance.

for another occasion, I had fun doing a demo to order a water valve to charge a battery via a pelton pico-turbine
https://www.youtube.com/watch?v=k7D69VpXGi8
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