... Time to replace the blades and get new storage

[arc]

Hi all,

I see it's been 2 years (almost to the day) that I posted last.

My PVC blades lasted about a year and a half (prior to exploding).

My goal:

To power one tiny RCA TV, my VAIO laptop and a 12V fluroecent light on a daily basis and act as backup (emergency power) to run the refrigerator if the power should go out for more than a couple of hours.

My (shoestring budget) AE system:

solar power - 37 watt panels

wind power - 115/230V split-phase conversion using (28ea) 1/2" dia. neos w/ home-made PVC blades

3 group 27 marine (so-called) deep-cycle 12V batts (in bad shape)

Small Steca (6.6A - I think) Charge Controller

2 rectifiers

DC Panel w/2 buss bars (+&-), a volt meter and auxilliary cigar lighter output

Aims 1250w inverter

AC 2 brkr Panel

Earth Ground for both panels, inverter and battery negative (8' copper clad)

Isolated house wiring from AC panel to 4 locations throughout the house.

(behind the fridge, living room, bedroom and office)

This past Winter my PVC blades got cold and broke loose during a heavy wind gust, so it's been all downhill since then.

Spring is upon us so it's time to get my tail in gear and do some repairs.

I just ordered:

(2ea) 6 Volt 200 Amp Hour AGM Batteries (8AGC2) to replace the Group 27's

(1ea) 12V Iota DLS-15 Battery Charger.

I didn't have very good luck with the group 27's that I had, so I wanted to be sure that I keep the AGM's topped off in times of little or no wind or solar activity.

Wind is on and off here (Pacific Northwest) and solar is a trickle at best during the Winter months. Even with little or no load, my current system is often not up to keeping my batteries in optimum condition (therefor the charger).

I really wanted to get some T-105's but I think the 8AGC2's should be a heck of a lot better than the group 27's.

I've never used AGM's but it's my understanding that to get good life from them I really need to keep them topped off, I hope the Iota will do a good job there.

Now for the genny repairs.

The PVC blades that I made before sure did work great, I may just make another set with a little bit more reinforcement near the hub. The last ones would start in 3-4 mph wind and start charging with 10-12 mph wind.

I made them from 10" diameter Sch 40 PVC pipe and had 4 blades (actually two crossed pieces sandwiched together with some 14GA steel, truss plates and (12ea) 1/4" bolts.)

The hub (truss plates) is still fine so I may just make 4 individual blades this time instead of crossing the two pieces. I figure that this might allow a little more flex and not shatter quite so easily. (The blades were 5 foot in diameter) Maybe I'll go for 6 foot this time.

The genny is mounted on a 20 foot tilt-down pole (2 1/2" steel pipe).

I have two 3" steel angle set in concrete at the base so the pole will tilt down using a come-along anchored to a ring set in concrete nearby. So far, the pole and base are holding up fine and make it (relatively) easy to access the genny.

The PM conversion should still be fine (I hope), I haven't checked it since the blade explosion. Worst case, I suppose I could have bent the shaft but it's pretty stout so I'm guessing it will be fine.

Guess it's time to bring 'er down and check it out.

Arc

[nothing to lose]

Did you paint your PVC blades to prevent UV damage?

If not they may have gotten a bit dry and brittle causing them to break, did you check if they were scratchy and brittle near the broken sections?

If they broke just because of cold and stiff, how cold was it??

[arc]

Hi NTL,

I did paint them with a Krylon product for plastic.
I'm not exactly sure why they broke but I suspect it's partly due to my design.
They were a bit narrow at the root. I think it was around 25F with wind gusts to around 40mph. I was actually surprised they lasted as long as they did.

I think I'll use the same hub but make 4 individual blades this time and add an extra bolt per blade.



















I'll try to find some Sch 80 PVC to see if that might work better.
Although it might be too heavy.

Wish I had the time and effort to make some wood blades, if I ever get my work bench cleared off, maybe I will do just that.

[RP]

Someone, I think maybe it was Norm (?) had a really neat way of mounting PVC blades using a hole saw to cut round slots in the edge of a wooden hub.  This would give a lot more support to the PVC and allow it to retain its natural curve and strength.

[RP]

Here's Jerry's method using a RotoZip.

http://www.fieldlines.com/story/2007/2/2/41629/53700

Notice how much of the plastic is supported in its natuaral shape and it only has one hole through the PVC so most of the original plastic is still there for strength.

[arc]

Good stuff ...
Thank for the link!

Since this is going on a PM Conversion, I would have to consider the method of attachment to the shaft, but this gives me some ideas for sure.

I like the support for the blades this way. My blades all broke off at nearly the same relative point. Whatever I can do to keep the stress uniform would surely help.

I think I need to do a little research about types and thickness of the material (PVC) too, I had some pieces of the original 10" pipe in the back yard an went to move it when it was below freezing outside. When I chucked it a few feet, it broke too. I bought it new, but it was stored outside so perhaps the UV's got to it then.

I always thought PVC was PVC but maybe there are some types a little more flexible (or forgiving) than others. Time to surf the web again ...
Is ABS any better in this regard?
Like I mentioned previously, Sch 80 might be the way to go too.

Thanks All!

Arc