Regulator for 12 volt dc windgen to lifepo4

[OldBawley]

Here is the thing. I have been living on my sailboat for over 30 years now, always at anchor, no marina or town quay with power. Had two 85 w solar panels, an Aerogen 4 wind generator on the yawl mast and in winter and autumn I mount a self made two bladed (1,75 m diameter) windgen on the starboard bow railing. The windgenerators had no regulation, I used them only for bulk charging the lead acid batteries. Solar was regulated by MPPT and took over the last charging.
I now decided our 40+ year old diesel was no longer wanted. Repairs without end. So I opted for electric propulsion. Bought a Lifepo4 battery and did some tests with a simple trolling motor.
Now the question. The lifepo4 battery has a much higher voltage as lead acid batteries. I measure 13, 4 volts at rest, and are charging over the old MPPT solar charger and a BMS.
Then we had a week of Meltemi, that is hard wind and I had the last day of those hard winds the Aerogen running. No regulation. In gusts the tension can go very short up to 15 volts.
Now, in the old days, my lead acid battery's had no problem absorbing that, the BMS protected the lifepo4 but the tension of the boat circuit run high. Just seconds.
Result : a varistor in my depth sounder burned out and the Dell car-air charger (12v to 19 volt) stopt working.
So I need a regulator for 12 volt Dc (I am using an Ametec motor) regulator with a dump load.
I tried a solar regulator on the Aerogen and that is no good. The regulator swishes the gen on /of in a very fast way so that the generator starts loud humming (no good no doit)
Any ideas ?

[mab]

Hi, as you've found out, most MPPT solar controller simply disconnect the power source to regulate the battery voltage. For a wind turbine you normally use a 'diversion' or 'dump load' controller along with a dump load (big resistor with a resistance value low enough and power rating high enough to dissipate the power the windturbine can produce).

I think there are a few available off the shelf, but if you have electronics knowhow you can make your own - basically it's a voltage sensing switch that turns on the dump load if the battery reaches a defined threshold (i.e.below the voltage that the BMS disconnects the battery), then turns off again when the voltage falls to a lower threshold. For a lead battery you might choose 14.4v on and 12.7v off, but I'm not sure what's sensible for liion - i think you would want the setpoints closer together than for lead.

[OldBawley]

To old to have anny knowledge of electronics, making something myself… no. Now, at around 16 h I hear the humming sound that tells me the solar regulator starts shutting down the wind gen.
At around 16h the sea breeze is the strongest, when I hear the humming sound I simply pull the fuse, effectively letting the gen freewheel without making any power. Half automatic system.
As I understand it (correct me if I am wrong) lead battery's are good at absorbing peak voltage spikes, Lifepo4 is not.
Will have to look for an off the shelf regulator with dump.
Some other thing. Since Lifepo4 has a higher voltage than lead, my self made windgen starts loading a lot later (rev) so I now try to make the windgen more performant. Have ordered a smaller (15 teeth) chain wheel for the Ametek, not received anything yet. Also ordered an “ideaal diode module) (see pic) to replace the Skottky diode who has a loss of 0,65 volts. The “ideaal” is a mosfet who acts as a diode, supposedly with less voltage loss.

[Adriaan Kragten]

On my website: www.kdwindturbines.nl you find a free manual of a 27.6 V, 200 W battery charge controller at the bottom of the list with KD-reports. This battery charge controller contains a voltage controller and a dump load with one Darlington power transistor and two 100 W resistors. The battery charge controller is meant for a 24 V lead accid battery but can also be used for a 12 V lead accid battery if resistors with another resistance are used on the dump load. The correct value for a 12 V battery is given in the end of the manual. The maximum power which can be dissipated can be increased by connecting several 200 W modules in series. The voltage controller is strong enough to supply the base current for several dump load transistors. The voltage controller contains a potentiometer with which the maximum charging voltage can be adjusted in between about 12 V and 30 V. So the given voltage controller can be used for both battery voltages.

The manual contains the theory of the dissipation of the heat in the transistor and the resistors, a wire diagram of the voltage controller, a wire diagram of the whole system and a technical drawing of the dump load. The system has been tested for several years.

[OldBawley]

Hello Adriaan, I will answer in English although I am Dutch.
I had seen your manual, also seen the video of You in Holland. Unfortunately I am not capable of making electronics myself. I have made the windgen (see  : https://www.fieldlines.com/index.php/topic,147282.msg1016517.html#msg1016517

and that is about all i can do. I am a mechanic, not an electrician. Thanks for the reply, here is a forum thread of an Dutch sailing forum where I ask about the problem with Lifepo4 battery's.

https://zeilersforum.nl/index.php/forum-hoofdmenu-37/73-stroom-elektrische-apparatuur-aan-boord/598777-onverwacht-gevolg-lipo-4-accu-s

[Adriaan Kragten]

I think that there is no way to solve your problems. A normal 12 V lead acid battery has an open voltage in between about 12.2 V and 12.6 V depending on the charging state. To charge the battery, you need a certain voltage difference which depends on the current and on the battery capacity. If you have a very big battery and a small wind turbine, the charging voltage may be below 14 V even if the battery is almost full. But for a full battery the voltage will become higher than 14 V if there is no voltage controller with dump load. A voltage of 14 V is the maximum voltage which 12 V equipment can have without blowing up. Voltage controllers normally limit the charging voltage up to 13.8 V for a 12 V battery (2.3 V per cell) because a lead acid battery can have this voltage for a long time without strong separation of water into oxygen and hydrogen.

Your new battery has a higher open voltage than your old 12 V lead acid battery. This means that you also need a higher loaded voltage to charge this battery. If you would use this battery in combination with a battery charge controler which limits the maximum voltage up to 13.8 V, almost no power will be absorbed by the battery and almost all power will be absorbed by the dump load. So to get a sufficient current into this new battery you need a higher charging voltage and a voltage controller which is adjusted to a higher voltage of about 15 V. But with 15 V, you will blow up your normal 12 V equipment.

A wind turbine which is designed for a 12 V lead acid battery and which is used in combination with a 13.8 V voltage controller plus dump load, supplies a loaded voltage of 13.8 V at high wind speeds. A loaded voltage of 15 V requires a little higher rotational speed as the Pmech-n curve shifts to the right if the voltage is increased (see my public report KD 78 for generator measurements for different voltages). If the matching in between rotor and generator is good for 13.8 V it will be a little less good for 15 V but it will certainly not be very bad and so I think that for the windturbine, a slightly higher voltage should not be a problem. The biggest problem is that the wind turbine has no safety system and that the maximum charging current is therefore not limited at very high wind speeds.

Blowing up your normal 12 V equipment for a higher battery voltage can be prevented if you place a 24V/12V DC-DC converter in between the battery and the 12 V equipment. Such converters supply a DC voltage of about 13.8 V at the outlet. But I am not sure if this converter works for a battery voltage in between 14 V and 15 V and you will also loose some power in this converter.

[OldBawley]

What my plan is at the moment :
I continue to charge my 12 volt lead acid bank (2 x 140 Ah ) with solar (over MPPT) and two unregulated wind generators.
I have ordered a Victron Orion battery to battery charger 12 to 24 Volt.
When that arrives in Greece  I can load the Lifepo4 24 Volt battery from the “house” 12 Volt bank.
The lead acid battery survived my unregulated windgenerators for decades. They can handle the short peaks that wind can give.
Last month I regulated the Aerogen 4 windgen over a solar regulator. It did not work. When the max  tension was there, the regulator started shutting down the windgen by very fast on / off pulses. That resulted in a mechanical vibration of the gen. That noise (I live on board) made me pull the fuse so the windgen started freewheeling. A sort of half automatic regulation.
After 2 weeks the regulator gave a sharp “Pang” and that was it. Burned.
The “Ideal diode” is on its way to Greece, I will test it as soon as it arrives. It should theoretically make my big wind generator (Ametek, geared diameter 1,72m ) more efficient. I now have a Schottky diode and lose 0,6 Volt which is a lot if the wing and gearing is optimised for 12 volt charging.
The whole experiment with the electric outboards to drive my 8 ton liveaboard sailing boat in case of no wind is going good. I was given a 1160 watt trolling motor (215 €) and have that one mounted on the stern, the tiller with the regulating thingy is mounted inside the boat. Works on the 24 volt lifepo battery. It moves the boat a lot better than me rowing with my 4 meter long oar or towing the boat with my 50 year old 2 hp old Seagull outboard engine.
I also repaired a given Torqeedo travel 801 electric outboard, works remarkedley well.
The old 450 kg heavy Perkins diesel is still in the boat, I refuse to use it.