I am trying to use a water turbine from China to charge a lithium ion battery. The water turbine is rated to 10 watts.

I figured that should be enough to charge the battery but I can only ever get about 0.1 watts from it.

I took it apart and it looks like it is generating 3 phase AC power and then rectifying it to DC with 6 diodes.

I am then using the LM22672MRE-5.0 switching regulator to regulate the voltage to the MCP73871 battery charge management chip.

Any tips on how to get more power out of it or are the specs just wrong?

This is the turbine I am using.

Here is a simplified schematic of the circuit I am using to rectify the 3 phase power and convert it to 5V DC. Should I be doing some kind of impedance matching to make this work better?

enter image description here

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    \$\begingroup\$ What is your water source? \$\endgroup\$ – Mattman944 May 4 at 1:33
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    \$\begingroup\$ @Mattman944 It's probably not Chinese water. ;) To the OP, it's likely the specs were produced under the best possible case and quite unusual, in practice. Solar panels, for example, are rated for equatorial insolation at noon in crystal clear air. Which, of course, is almost never the situation they are operated under. \$\endgroup\$ – jonk May 4 at 2:38
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    \$\begingroup\$ Can you measure the generator Voltage vs current without regulator using an active load? (power NPN) , until Vrms drops 50%.(V/I) (briefly) then Voc vs flow rate. NOTE the spec is charging current maximum =220mA. It says DC 0-80V but what do you get? That implies source impedance is 80V/0.22A = 360 ohm much higher than your regulator Zin yet with matched load 360 max P=8.9W \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 May 4 at 2:51
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    \$\begingroup\$ What is the head and flow rate you are supplying the turbine with - that will tell you the max possible input. \$\endgroup\$ – Solar Mike May 4 at 5:27
  • \$\begingroup\$ you're going to need some protection to prevent the generator voltage from exceeding the 42v maximum allowed by the LM22672 \$\endgroup\$ – Jasen May 4 at 5:31

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