Sending output to a pump, and excess to battery

Just stumbled on a web site that reviews 12V solar air pump/compressors!
(http://www.thepondreport.com/solar-battery-pond-air-pumps.shtml)

They say that "WHITE-H20™" diaphragm compressors and air pumps are pretty good (they are the DC-8, DC-15, DC-20 and Dc-40 mentionned in an earlier post), but not to expect more than a few months of use from them:

quote:

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Buy "The Pond Report" Highest Rated Solar Air Pumps
Over the years we have tested and evaluated the staying power and effectiveness of many DC 12V and 24 Volt pumps and one thing weve constantly noticed is that no matter what type of pump you buy, these 12V pumps are not going to give you years of service so buy a good cheap one! When I say cheap I dont mean some ebay special deal on a pump made in some far away country without care for product consistancy I mean buy a good qality pond pump that doesnt cost too much because you will be buying replacements every 3 to 9 months of continuos usage.

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They have also reviewed "pur-water" compressors, which are the ones being sold by Kelln Solar that I mentionned in my previous post :

quote:

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Pur Water
Simple DC air pumps look like a decent copy of a Thomas type blower built in to the dugout solar aerator developed by Kelln Solar:
Specifications Capacity: Aerates a 2 million gallon dugout @15ft Output: 2.9CFM Power Source: Solar Direct Compressor: Pur-Water Diaphragm continuous-duty cycle - dual Bleeder Valve System Voltage: 12V Mounting: In dugout Warranty: System - 1 year, Panels - 20 years Suitable for medium vegetation Items included with each system Pur-Water Compressor 12" Diffuser c/w Check Valve 4-50 Watt Solar Panel Panel Stand 8A Linear Current Booster Enclosure - weatherproof Spare diaphragm kit 50ft weighted hose, 50ft ¾” poly-hose

Available at Kelln Solar
www.kellnsolar.com

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Im not sure being a copy of a thomas pump is so good though:

quote:

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Thomas 907 and 2907 Series Air Compressors - These are good quality but high priced and again the inconsistancy of the units makes us a bit nervous but the fact they can deliver 3.2 CFM and 14 PSI make this little grinders seem like a good deal if you can buy a few when they fry.

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later!

Found this *english* link from Agriculture Canada about solar aeration of dugouts (hey, I just learned a new word!).

http://www4.agr.gc.ca/AAFC-AAC/display-afficher.do?id=1187620075153&lang=eng

The numbers are the same than in the french paper, which is a bit weird.

I noticed in your link there was only $10 difference between the DC8 and the DC15
Instead of buying 2 DC8s, why not buy the DC15 and run it at half power (through a pwm controller) say when the batteries are between 13V > 14V and at full power if the battery voltage exceeds 14V.
Also the compressor will last longer than one that runs flat out all the time.

I know nothing about PWM controllers and DC motors, but this sure sounds interesting :)

Anyone?

PWM on DC motors is sort of like efficiently running the pump at 8V. Or 10.2364V.

I believe it would take some testing on specific DC diaphragm pumps.
I tried something similar a long time ago, and the reeds didnt seem to work quite right(or something?). It used power and pumped some air, but the CFM/W went way down.
Simple enough to try.
G-

Thanks again Ghurd, for this and the couple emails.

Just a quick note to say Im still alive. Ive put everything aeration-related on the ice for now, as Im currently concentrating on building my small wind turbine.

I received my motor yester day and "horror and damnation!" Its got a left-hand thread on it!

Just ordered a couple left-hand nuts from fastenal (I didnt know about them and theyre just 5 minutes from my place.. sweet!). Im also about to pick up a couple used circular saw blades I from a guy on freecycle :)

Slowly getting there...

Later!