Navitron Renewable Energy and Sustainability Forum

Energy/Electricity Storage and Use/Grid Connection => Off-Grid, Batteries & Inverters => Topic started by: marc on March 03, 2008, 04:29:06 PM



Title: 2 wind turbines, 24vdc and 12vdc - how do I connect these?????
Post by: marc on March 03, 2008, 04:29:06 PM
Hello Wind Turbine Guru's,

Having a 'blond' day. Here's the equipment.
I have 2 wind turbines - one is the Navitron 300 watt portable which has a built in charge controller etc and kicks out 12 vdc. The other (no names) is a 2.2kW which gives 24vdc - no charge controller, just a bridge recitifier.
I intend to use 4 x 12vdc, 110 Ah batteries to being with.
Ideally I would like both turbines to supply the same battery bank.
However, with one turbine giving 12vdc and one giving 24vdc I guess I am going to seperate charge controllers, 2 inverters, 2 dump loads, and well............. 2 of everything (or am I missing something?)

A very basic schematic diagram would be welcome. Awaiting your response Ted, Martin, other guru's.

Thanks in advance
Marc


Title: Re: 2 wind turbines, 24vdc and 12vdc - how do I connect these?????
Post by: martin on March 03, 2008, 04:37:23 PM
I'm worried............ :-\
If in doubt, start from the other end..........what voltage do you want this combined bank to be? ::)
My immediate temptation is to say "don't even try combining them" - 2 batteries to give one 24 v bank, 2 batteries to give a 12v one ;)
The 300 watter should in theory obviate the need for further controller/dump loads on the 12v system.....but you'll need something for the 24v job (ditch the 24v turbine, and have 4 batteries @12v? ;D)


Title: Re: 2 wind turbines, 24vdc and 12vdc - how do I connect these?????
Post by: marc on March 03, 2008, 05:04:35 PM
Hi Martin,

You are spending too much time on the forum (as per another recent post, 80% etc) but thankfully to the benefit of us all!
Regards the voltage i want its kind of academic ( i think) as it will go via an inverter so ultimately  i want 230 VAC out so just need to buy the right inverter (MSW - probably - because of cost restrictions).

Cant possibly ditch the 24 vdc turbine - too expensive I'm afraid even though purchased as a 'try it' product. So, thats what we've got. May not be the best combination but thats it.



Title: Re: 2 wind turbines, 24vdc and 12vdc - how do I connect these?????
Post by: Bob on March 04, 2008, 07:19:03 AM
Hi Marc

I don't think you have anything like enough battery capacity to a 2.2kw machine.

However this one way to do it.

Connect the 12 turbine to a 12 v battery

Connect the 2.2 to the other two batteries wired in series to give 24v

Get a large DC-DC converter and a batter sensing relay.  Use this to connect the battery banks together.  Which way you do this depends on your inverter.

Purchase a second battery sensing relay and and make yourself some sort of heat dump.  Set the second relay to sense the voltage in the battery where the power is ending up and dump what you don't need.

If you think that this is insane the I'm sorry to say that I am the man who already has most of this in his shed.  The only difference is that my batteries total around 1500Ah and I don't use the final heat dump.

If you need addresses for the kit I have them.

Good luck

Bob


Title: Re: 2 wind turbines, 24vdc and 12vdc - how do I connect these?????
Post by: marc on March 04, 2008, 02:55:41 PM
Hi Bob,

Wow - that's quite a lot of work but I understand what you mean (I think).
Surely this issue must come up when people combine PV & Wind for Hybrid systems?
Re the batteries I do intend adding to them - just time and money constraints for now.

I am wondering whether it will be easier to adopt Martins suggestion and forget trying to combine them.
It may even be cheaper, easier etc to use two inverters and use 2 batteries for the 300w and 2 batts for the 2.2kW for now.
Oh well, lets see what we end up with.
Thank you Gents
Marc


Title: Re: 2 wind turbines, 24vdc and 12vdc - how do I connect these?????
Post by: jason on March 04, 2008, 03:04:46 PM
Hi Marc
is it worth using the 12v wind turbine and use those batteries for the 24v system and buy one good inverter  just a thought
Jason
 


Title: Re: 2 wind turbines, 24vdc and 12vdc - how do I connect these?????
Post by: Paulh_Boats on March 04, 2008, 03:52:41 PM
Keep it simple - I don't think mixing 12 and 24 will ever work properly.

I suggest you sell the 300W turbine and use the money to fund extra equipment for the 2.2kW turbine.

Is there a useful need for this power? If it were me I would get a grid-tie inverter for an easy life.


Title: Re: 2 wind turbines, 24vdc and 12vdc - how do I connect these?????
Post by: martin on March 04, 2008, 03:54:24 PM
one of the big problems is going to be that you're sorely short on battery capacity for the larger turbine - in a good breeze, at 24 volts it'll be whacking out around 90 or more amps :-X
If you have all 4 batteries in use at 24v, that gives you 210 amp/hrs - classically you shouldn't be charging at more than around a tenth of that - 20 amps - the big turbine will be shovelling charge in at such a rate that I wouldn't think they'll last very long (even with dump loads).
In all seriousness, for a cheap stopgap solution, use all 4 batteries for the 12v system, and connect the big turbine directly to either a suitable 24v immersion heater (s) or dump loads, and save up for a good big battery bank - then the immersions/dump loads can be used as such - in the meantime you've had the benefit of the big turbine as water or air heating, at not a vast expense! ;)


Title: Re: 2 wind turbines, 24vdc and 12vdc - how do I connect these?????
Post by: jason on March 04, 2008, 04:14:45 PM
Why not use 24v turbine into the battery bank,dump any excess into an immersion heater and add to the battery bank as you can afford it
jason


Title: Re: 2 wind turbines, 24vdc and 12vdc - how do I connect these?????
Post by: martin on March 04, 2008, 04:32:11 PM
because in getting the batteries up to dump load level they'll be being charged at a much higher rate than is good for them, and will probably trash them quite quickly - if he just "permanently dumps" the output from the big turbine until he gets the big battery bank, he's saved the cost of a BIG dump load controller, and the batteries will be very happy working as 4 together from the 300 watter! ;)
AND you should never "add to a battery bank" - batteries should always be from the same batch, age, and initial charge, or you decimate their life, owing to differing internal resistances........ this should help http://www.smartgauge.co.uk/batt_con.html (http://www.smartgauge.co.uk/batt_con.html) 8)


Title: Re: 2 wind turbines, 24vdc and 12vdc - how do I connect these?????
Post by: jason on March 04, 2008, 04:50:42 PM
my thoughts are that a 300w turbine would not supply any useable power most of the time, the 2.2kw unit would be produceing on average 500w ish most of the time as an average  and 4 45 on ebay for a 50amp volatage regulator plus a 24v immersion or a couple of navitron dump loads.
i would be willing to use this set up  as the regulator operates at 14.4 volts. 220ah @ 24v is about 5.3 kw and at 500w would take moor than10 hrs to fully charge.
jason


Title: Re: 2 wind turbines, 24vdc and 12vdc - how do I connect these?????
Post by: marc on March 04, 2008, 05:14:26 PM
Well Gents,

Lots to digest there.

I know that I will need more batteries but as I am in France unfortunately can't get from Fleabay UK (shipping etc) so lumbered with the local battery cost which is not insignificant.
For some background info, I have these 2 turbines at a very reasonable cost so just want to use them to their best. The plan is to hopefully use the output/s to power my chalet / office without reliability from the utility company (EDF).
Just don't know, grid tied, battery only for the chalet, etc etc.
Guess more thought is called for?

Footnote: really appreciate all the info received here - good, weird or otherwise. It's a learning curve for many of us.
I just want to reduce my reliance (carbon footprint) from the utility companies.

Thanks to all,

Marc


Title: Re: 2 wind turbines, 24vdc and 12vdc - how do I connect these?????
Post by: martin on March 04, 2008, 05:21:51 PM
Jason - do try it, and let me know what colour the magic smoke is (or how little time the poor batteries last) ::)
90 amps through a 50 amp controller - and charging at 4 times the recommended rate in a blow......... ::)
You have to design for the maximum it may recieve, not an "average", any system is as good as it's weakest link.......... ;D
I'm  just hoping to god you don't design boats to go to sea - "oh I'll design it to be fine in a force 4"......... ;D


Title: Re: 2 wind turbines, 24vdc and 12vdc - how do I connect these?????
Post by: Stefan (S.T.E.F.) on March 07, 2008, 07:09:38 PM
I am an absolute novice but can't you use the 300W turbine for 12V lightning in the house and the 24V turbine for the 240V stuff? That would mean 2 systems but only one inverter.
I've been thinking about something like that myself....
Stefan