Testing charging capability without voltage regulation

[harrisonpatm]

Disclaimer: I am fully aware that unregulated charging a battery is a bad idea. This inquiry is for testing purposes only.

I'm playing around with some wind turbine setups, and I want to see if any of my configurations will charge my 14s Li-Ion bank. I can see that unloaded, my various small generators can easily surpass 50-60v. I would like to rectify their output (some are 3-phase, also playing with stepper motors and their 2ea 2-phase), and then connect their output to my battery to see their charge capabilities. I would monitor it and use a multimeter to measure current output. This should be okay, right? Normally what you would want to do is first connect the rectifier output to a buck converter or other voltage regulator, to make sure that the voltage output doesn't overcharge the battery; i've done this dozens of times. But for testing purposes, shouldn't my huge 10kwh battery easily act as a "load" for the tiny stepper motor and regulate its voltage for the purposes of testing its current capabilities?

Again, I know this is not standard practice. Just want to see if anybody has done this before, I want to check various turbine arrangements without having to order a 56v buck converter. Thanks!

 

[OffGridInTheCity]

I write this to provide a view / discussion since you asked - not to say you shouldn't experiment or to criticize.

This is similar to connecting solar panels directly to a non-charge-controller for charging under certain conditions but.... a charge controller is so much better and safer due to the extreme variability of solar. Wind is similar - much better to route thru a wind oriented charge controller (Midnite Classic comes to mind) to get some reasonable efficiency.

The trouble with manually bypassing the 'charge controller' function is you have to manually, sample metrics + take-action. Won't result in efficient charging or useful metrics.

I'm reminded by my 1st powerwall (7s50p) and didn't believe I needed a BMS. I decided I could measure the packs manually and all would be fine. I eventually discovered that there were voltage swings I was missing - and they were severely over discharging the cells - oops!

 

[harrisonpatm]

I write this to provide a view / discussion since you asked - not to say you shouldn't experiment or to criticize.

This is similar to connecting solar panels directly to a non-charge-controller for charging under certain conditions but.... a charge controller is so much better and safer due to the extreme variability of solar. Wind is similar - much better to route thru a wind oriented charge controller (Midnite Classic comes to mind) to get some reasonable efficiency.

The trouble with manually bypassing the 'charge controller' function is you have to manually, sample metrics + take-action. Won't result in efficient charging or useful metrics.

I'm reminded by my 1st powerwall (7s50p) and didn't believe I needed a BMS. I decided I could measure the packs manually and all would be fine. I eventually discovered that there were voltage swings I was missing - and they were severely over discharging the cells - oops!

Not planning on leaving it up, literally just want to

In any case, i realized that I could run a simple test, and as far as I could tell, nothing happened. Zero current output after my rectifiers. I tried two different small generators I wanted to use, rectified, and output attached to a line of my home battery. Nothing. Measured with multimeter and a shunt I have. Tuned by hand, and by power drill. Didn't even feel like it was loaded at all.

I don't understand enough electronics to know why this didn't work. I'll start looking for a buck converter than can hit my target voltage.

Current wind turbine goals, aren't to actually make usable power, I just like trying out different configurations as a hobby. I was just hoping to use my existing infrastructure, rather than charge a bunch of random 12v batteries around the house that I can't easily use.

 

[100kwh-hunter]

I chip in on the advice of offgridinthecity.
Use a solar charger for everything that is feeding your battery.
I use a victrin solar charger 100v/20a with a bridge rectifier for my wind gen.
The test was very satisfying btw.

Most li ion chems can have MAX 4.5v (max total 63v)even held up for a couple of hours your are heading for troubles.
why order a buck converter?
Just buy a simple solar charger, victrons are cheaper in my country than midnight, so go ahead and please order a charger.
Just 140 euro for a 100v/20a i can connect 3 1kwh gen's on it.

 

[harrisonpatm]

why order a buck converter?
Just buy a simple solar charger, victrons are cheaper in my country than midnight, so go ahead and please order a charger.
Just 140 euro for a 100v/20a i can connect 3 1kwh gen's on it.

It's valid, it's just that I'm mostly experimenting, playing around with different configurations, making them by hand. Don't know what does and doesn't work yet. So if I were to have a reliable, higher-power wind turbine, that I know produces significant current, then yes I would absolutely just take the turbine's output (after rectification) and stick it in a charge controller. But until then, it's not worth spending 140 euro.

I use a victrin solar charger 100v/20a with a bridge rectifier for my wind gen.

Do you use a dump load?

 

[100kwh-hunter]

Do you use a dump load?

1kwh wind gen-->3 wires to rectifier---->two wires to mppt--->two wires to battery.
The "maiden run" was with moderate wind speeds 50-60kmh.
The mppt is also connected to some solar.
My plan is to connect wind gen and solar to one mppt.
But i can switch between them.
When we have wind we dont have sun and vice versa.
So yes in this one its granted to you, i also dont think its worth (right now) to spend a extra 140 euro.

But i am going to change somethings, so i will have left over 3 of them.
I want to have a higher V from my arrays.
I think 90vmax is just not enough, so i want to go to triple 35v and triple 48v and double 88v.
As far for the wind gen this will work after change of my system.
I also think i have enough room to connect number two wind gen on the same mppt.

So yes i completely understand you, its a lot of money.
But on ali they sell mppt's!! for under 45 euro and pwn's!!! for 25 euro.
That is what i would do if i was going to conduct your experiment.

I am afraid that the buck converter, will not survive if there is a wind spike.
I also understand the need for breaking the wind gens if wind is speeding to much(you and i will get a ticket....sigh)
But when wind is going to be 100kmh i will let them down(flag post principle in the Netherlands, a hinge on the base)
Or put them on the fence or roof that i can easy exces

I hope you post a lot more of your endeavors, i am looking forward to them.
.

 

[harrisonpatm]

The nice thing about doing these wind experiments on inefficient and cheap buck converters is because they're inefficient. The way I see it, if I can get any sort of regular power out of a turbine using a crappy simple buck converter, then if I put the same setup on an MPPT, it should produce even more. Besides, I mostly just do it for fun.

I hope you post a lot more of your endeavors, i am looking forward to them.

My last for-fun setup was a simple garden decoration windmill, but using 3d printed turbine blades that are copies of the same airfoil used on the Ingenuity Mars helicopter (RIP). NASA posts a ton of their work to the public, so it's a simple matter to find a CAD file of their helicopter blades, convert it to an STL, design a hub, ect.

It's a really good design, and really weird. Spins crazy fast in almost no wind, which makes sense, seeing as it was designed to push an atmosphere 100x less dense than ours.