How long to charge a battery bank?

[Jedon]

Well I already have a 12x16 shed that houses all my batteries and inverters and generators, hate to build yet another one!
I have two 5500W inverter/chargers already.

Or rectify, charge a BIG battery bank at your house/loads, and use a honking big inverter to run it all

This is better since I already have it...

[mike90045]

So if using a small inverter and batterybank at the source, stepping it up to 480VAC, and back to 120v for battery charging, may drop your efficency down to 175W : 24hr = 4,200 Wh day. Not bad.

[Jedon]

I don't understand why I can't just generate unregulated AC at the wheel and then step down and rectify into a charge controller?
I could probably get a 240V generator head free off an old 1800rpm generator, I suppose the speeds wouldn't match up and gearing would kill efficiency?

[Jedon]

Like system #2 here: http://www.homepower.ca/ac_hydro.htm but less flow.

[mike90045]

You could generate wild AC at the turbine, but that is often 3 or 6 phase AC, needing that many wires. You need broad band (60- 400hz) power transformers, most small alternaters aren't over 24V.  All depends on your skill and comfort level.   And get greasable bearings on the alternator, it's likely to see in 1 month, a vehicle's lifetime of running.

[mbryner]

You can generate wild AC, run as high of voltage as possible to prevent line loss (especially at that distance), rectify it, and feed it to charge controller.   Again you'll probably need filtering as we discussed on other threads.   Phase depends on the alternator of course, and more phases will make for easier filtering (right?).  And make sure you have a dump load!   

This is something I've discussed a couple times with our local guy from Alternative Power and Machine, who builds these turbines and customs alternator.   He's also written multiple articles in HomePower, and is one of 3 outfits Outback approves.   It is what I'm planning on doing in our seasonal stream later on.  Should work fine.

[Geno]

I would imagine the more phases you have the less filtering you need. I think ripple decreases with each additional phase. I won't be filtering at all on my portable, 3 phase battery charger. I have a stream on my property that flows at 5-25 gps with the potential for ~75' of head. Tapping it would be logistically difficult but there are no environmental hurdles. If I do that it's way down the road. Now that I think of it I may want to build some kind of quick dam to get it grand fathered in if the rules change.

Thanks, Geno

[Jedon]

Last night when I turned off the SR2 the batteries were on float. This morning, no power. Inverters had shut down and the voltage had gone back up to 47V. Something is obviously amiss, thank you all for your suggestions, looks like I have some work to do sorting out what is wrong. Bad batteries is probably an easy diagnosis, I do have a set of golf cart batteries I think I'll try first thing.

[mike90045]

Charge those batteries up, ASAP, the longer they are below 75%, the more irreversable sulphation they incur.  then try out the spare set.

How large is the set that shut down?

[Jedon]

The generator is charging them right now and has been for an hour and a half or so at 45A@120V.
The battery bank is 16 420AH L-16H's.