Charge controller needed for mini hydro

39 Posts
Jan 4, 2010 08:17 pm
Charge controller needed for mini hydro

Hi, I'm trying out a new Ampair UW100 submersible hydro (12V, up to 8.3A), and not impressed with the manufacturer's charge controller since the set points are not customizable and when batteries are full I'm just wasting power since it's just a shunt-type charge controller.  Does anyone have advice on a different charge controller I could use, preferably one which doesn't have the problems mentioned above (ideally one which can regulate charging AND divert power to a dump load such as a hot water heater element when the batteries are full)?  The controller must be able to handle up to 47VDC input, since that's the max no-load voltage produced by this hydro.  Normal voltage with load is 18-20VDC, up to 8.3A.  Thanks for input,
« Last Edit: Jan 4, 2010 08:19 pm by Matthew Edelen »
351 Posts
Jan 5, 2010 01:10 am
Re: Charge controller needed for mini hydro

Diversion control is the way to go with small hydro (or wind) turbines. If you try putting a PV type charge controller on it, you will burn something up.

If you don't like the high low choice of the ampair, you could use a Xantrex C series controller instead. (as a diverion controller, not a charge controller.)
39 Posts
Jan 5, 2010 10:40 pm
Re: Charge controller needed for mini hydro

Thanks for the reply.  I was thinking of using the Xantrex C series as a diversion controller, but the manufacturer of the hydro warns that the voltage produced by the hydro is too high for unregulated direct connection to batteries and may cause battery damage.  (Also wondering if my inverter will shut down due to high voltage input, being also connected to that battery bank on the same terminals.)  Others have said they direct-connect these hydros without any problems.  What do you think?
351 Posts
Jan 6, 2010 02:21 am
Re: Charge controller needed for mini hydro

It really depends on your battery bank size and your usage pattern.

A lot of the manual is written for marine applications where the battery banks are smaller than RE battery banks. In the marine application, there may not be a daily draw on the battery. So, there may be long periods of full battery banks and high voltage.

In a RE application with daily usage, the full battery period will be fairly brief, or may not even exist. Usually, a diversion controller is all you will need.

Don't be surprised if your actual generation is less than you are figuring. The "Jack Rabbit" is known for it's optimistic performance curves, particularly for an in-stream application.

39 Posts
Jan 11, 2010 06:33 pm
Re: Charge controller needed for mini hydro

Thanks, Ken.  That fits with what the distributor for the mini hydro says.  I'm curious, has anyone else tried a different setup, or found a different charge controller capable of handling this kind of load?  This system is for a jungle outpost which may be vacant for weeks or months at times, so I'm still interested in the possibilities for a charge controller and not just a diversion load controller. It seems like there are so many choices out there for PV controllers, but when it comes to wind & water turbines, each unit just has its own proprietary controller.  If you don't like it, what other choice do you have?
« Last Edit: Jan 11, 2010 06:35 pm by Matthew Edelen »
351 Posts
Jan 12, 2010 02:19 am
Re: Charge controller needed for mini hydro

PV is an exotic form of generation.  The controller is trying to coax more power out of the panels for better efficiency. It then turns around and simultaneously looks at protecting the battery. That is why you have solar charge controllers.

With your hydro set up, the generator is going to produce a certain power level based on the current flow and the excitation logarithm. That power will come charging out like the bulls of Pamplona.  It is active generation, not the passive generation of PV.

Until you are in a hydro unit large enough to justify the expense of flow control and excitation control to back the production down, you just have to take the full amount and do something with the excess.

You seem to be thinking that because solar works better with complex control, the same complex control is needed on hydro.

With diversion control, all it needs to worry about is protecting the battery. When the battery voltage hits the preset level, it starts diverting enough wattage to maintain the appropriate voltage.  When the battery is full, all the wattage will be diverted.

Something you said gives me the feeling that you think dumping power is bad.  Question for you.  What is the difference between dumping excess power off of a hydro, and not producing the same amount of power with a PV panel because the controller choked it off?

To me, they are both equally wasteful.  The difference is that if you choose the right diversion load (e.g. preheating hot water or pumping water to storage) you can have more efficient use of your generation. (Higher capacity factor)  You may also be saving some other form of energy.
« Last Edit: Jan 12, 2010 02:22 am by ken hall »
39 Posts
Jan 12, 2010 06:16 pm
Re: Charge controller needed for mini hydro

Thanks Ken.  Actually I totally agree with you about the energy wastage.  I'd definitely prefer going with the diversion controller setup, in order to NOT waste all that extra energy (and also to have hot water in the jungle for those cool rainy days). That's one reason why I haven't bought the manufacturer's shunt-type charge controller for the hydro.  Using the diversion controller setup, I'm just nervous about whether the unregulated hydro power input will fry my batteries...or shorten their life--you know, the "bulls of Pamplona" Smiley.
« Last Edit: Jan 12, 2010 06:20 pm by Matthew Edelen »

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