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cemdev asked

Victron 100/20 SmartSolar as hydro charge controller

I have a small hydro setup that I'm trying to get up and running. I've purchases a victron 100/20, awaiting for it to arrive.

My generator currently produces 62v DC after being rectified from 3 phase AC when running with no load. The generator is a motor off a segway es2 scooter - rated as a motor for 300 watts constant/700 watts peak @ 36v input.

My water source is very steady, there are no seasonal variations as I'm taking only a very small fraction of the total water source.

So, my thinking was that I had no need for an MPPT controller, and a cheap PWM controller would do nicely.

However, I'm running a 24v battery bank, so a PWM controller limits the motor RPM so it generates ~28v. This seems suboptimal.

Using an MPPT controller, it should spin at the top of the power producing curve, somewhere between 28v and 62v, and then convert the excess voltage to current, which is its primary appeal for me.


My questions are:

1. Are my assumptions correct?

2. Given my free-spinning, no-load output is 62v dc, and the victron 100/20 controller is rated to 100v input, I should have no need for a diversion/dump load, is that also correct?

3. Can I assume that the most power I should get from this motor is about 300 watts, as that's it rating when used as a motor? Or can it produce more as it certainly can produce more volts than its rated 36v.

4. Using a PWM controller, to optimise I would want to find a runner (propeller/impeller inline in tube, I'm not using turgo/pelton) that provided maximum torque at the RPMs it runs at 28v, while making sure it never drops below 28v (I can print new runner designs, so this was my planned optimisation route). Using MPPT, I have more flexibility as long as RPMs remain in a range to produce over 28v on full load, and remain under 100v with no load. Is that correct?

Apologies if the questions are basic, this is my first hydro build, it's been fun so far, but I have much to learn.

I understand the victron controllers are designed for solar, and hydro isn't supported, but I see a number of people on here who are using them as hydro controllers, so thought I might get some useful information here. Many thanks!

Hydro and Wind Power
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wkirby answered ·

I know of one member here who has run his cabin using a 500W pelton turbine feeding into a Victron MPPT. It's important to ensure that the turbine Voltage cannot exceed the MPPT input maximum. You say that the maximum you can see is 62V, so it should be OK for you. Try to to overspin your turbine though, the bearings get hammered.
Use the battery charge current limit to prevent loading the turbine too low which should server to keep the RPM and Voltage a a good power level.

See this thread if you have not seen it already:
https://community.victronenergy.com/questions/1695/wind-turbines-and-victron-charge-controllers.html

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cemdev avatar image cemdev commented ·
right, i've already fried one (very cheap) controller for putting 62v to it when it had a limit of 55v, so I'm acutely aware of the upper limits. If this happens on a victron, is it a fuse that needs to be replaced, or is the unit toast?


Moving forward, I consider 80-90v to be my upper limit for free-spinning when it comes to propeller/impeller design to stay safely under the 100v victron limit, so I'll optimise for torque rather than speed when playing with new designs to gain efficiency. Relatively easy-ish. The generator itself seems happy running at those higher speeds (they're still not really that high) when not under load.




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wkirby avatar image wkirby ♦♦ cemdev commented ·
The 100V limit is a hard limit, it is the Voltage limit of the mosfets inside. A fuse will not help you if you exceed this limit.
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