What Batteries Do I need For 300W Turbine

[ENIGMA]

So Mark,why don't you get a few batteries from a scrap yard,like I suggested,just to experiment with and if you" mess them up" you haven't lost much.

[Ireland-or-bust]

hi,

looks like thats what i will have to do.

at least until i can get a definitive answer on what batteries i actually need.
Ideally from someone who does'nt want to sell me batteries :-)

Mark

[Ireland-or-bust]

I managed to find some good used car batteries today.
4 x 55ah each.

I'll give them a go and see how long they last.

I suspect the plates will wear thin but i only paid 30 euro for the lot so not bad all round.

[John Headstrong]

nice one, good price

I have 2 car batteries that I run experiments on for my system. I will lash out some money soon for a small bank of batteries.

people will say "oh, they are no good" but I once lived totally off grid with old car batteries and a very basic system. I bought a thing called a "optimate" it is a slow charger (from the mains) but it did bring batteries back from the dead, out of 6 that where dumped inside an old car outside a squat I got 3 back to life. it paid for itself in the first week when I sold one of the revived batteries (I even gave 2 months warranty!!)

[Ireland-or-bust]

Hi John,

Was it one of these you got....

http://www.vertar.com/battery-chargers- ... optimiser/


If so did you use it to revive batteries that the wind turbine killed?
Or just batteries you found.
I'm not so sure on the physics of reviving batteries, i thought once the plates were gone, they were gone!

Mark

[John Headstrong]

Hi John,

Was it one of these you got....

http://www.vertar.com/battery-chargers- ... optimiser/


If so did you use it to revive batteries that the wind turbine killed?
Or just batteries you found.
I'm not so sure on the physics of reviving batteries, i thought once the plates were gone, they were gone!

Mark

it was a older version optimate 2, I used it to revive batteries that I found/acquired (the area I lived in had loads of dumped cars at the time)

I was totally sure on the physics of reviving batteries once upon a time, but then I got the optimate and forgot all the 'pulse charging' 'float charging' and other associated jargon and what it meant.

[bar]

Hi John

car batteries are not really suitable for your proposed use as they are built for high initial load and will not be built sustain constant draw. you need heavyduty batteries used in boats forklifts standby power systems etc. most of these flooded lead cell.

when i was searching for batteries i found the best battery source for cheap second hand batts was ex MOD - submarine batts are brilliant; and national grid (and BT). all of these change their batts - for standby power - out regularly and sell them off. they are typically 2 volt cells in glass bodies and can be refurbed.

sizing is not easy. points to take note of are

- discharge level of battery - higher discharge less life to the battery - best not lower than 50%
- when sizing a batt bank look at C20 rating - which in the amphour available with discharge over 20 hours. this varies because the faster you discharge the batt the less you get from it.
- therefore you need to double amphour capacity of bank
- turbine will have cut-in wind speed - where it starts to produce current - and minimum optimum wind speed where it delivers design output. this is quite high and should figure in analysis of your location and site.
- losses in the system
- batt bank needs equalising occasionally to keep all batts working the same. this is mostly done by a generator.

i bit the bullet and bought new (and nice) in the end. not cheap but i should get 15 to 20 years from them.

[JayBee]

John,

If you read up on general deep cycle battery use, in RE applications, then you might read of people talking about a 20% rule. Regardless of what is stated by the manufacturer, you don't want to use more than 20% of the full charge so as to protect the battery.

You want to be recharging your batteries afore they hit 12.4V Ideally you want to recharge the battery from wind or Sun the moment it is taken off the battery.

To size your system you need to work out how much power you are going to use.

You say you have over 200W of lights but you are not going to have them all on (you better not!) at once, and you will have other items.

First, work out your typical power usage per day. Get yourself a power meter to plug into the wall, between socket and gadget plug. Determine the power for each device in the house. Multiply by the typical number of hours of use per day. Add up for all devices in the house.

You will now have your daily power use. That will also tell you what 20% of your battery bank should be because using any more will hasten the death of your batteries.

For example, if you use 1kW per day then that is your 20% maximum down draw from the battery bank hence you need 5 times that amount (ie 5 kW) in total battery storage.

If you have a 24V system then 5000W / 24V = 208A of current. Also note that batteries don't give all that is displayed on the label so say for the above system you are looking at 2 x 12V 220Ah batteries.

You are indeed wasting your time with car batteries, they just don't like to be cycled like deep cycle batteries. As soon as you start your car the alternator is recharging the battery. Your wind turbine just won't do that all the time, even if the wind is blowing.

Personally, I would not have bought a wind turbine. You will need to rethink your system after making the necessary calculations.

Do get back to us when you are ready. For a Kilkenny man to be helping out the poor yellow bellies of Wexford is always a pleasure.