Renewable Energy Questions/Discussion > Automation, Controls, Inverters, MPPT, etc

24v battery bank charger q's

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birdhouse:
hello-
i've got a 24v battery bank as part of my renewable energy set-up at my ranch.  the bank is about 450Ah @ 24v.  there are times in the winter when the solar and wind just don't keep up with the use. 

i also use a honda eu-1000 to power up a 32' airstream trailer.  that will slowly be put on the RE system, as bulbs get changed out ect. 

so i was looking on ebay at 24v chargers, and anything ove 3-4 amps starts getting really expensive.  so, then i found these chargers designed for Mac laptops.  at $9.65 for 2.6 amps, they're the cheapest "dollar per amp".   idea being, buy maybe 6 of these chargers and wire them up all in parallel.  so 6 would give a 15+ amp charger that could be plugged into the eu-1000. 

would this work?  any ideas?

is it easy to make a "dumb" 24v charger?  i've got a ts-60 in dump mode, so it could be the "smarts" for the dumb charger. 

thanks!
adam

specs for laptop charger:
Features:
1.Input: 100--240V, 50-60Hz
2.Output: 24V 2.65A
3.Power: 65 Watt
4.Smart device surge protection for over voltage, temperature and short-circuit protection
5.7.5*2.5mm

Specifications
Package include:1*APPLE G4 PowerBook 15" 17"  AC adapter

Compatible with
G3/G4 all Snow/White Apple iBook 500 mhz+ Apple iBook 12-inch Dual USB
Apple iBook Late 2001 Model
Apple iBook G4 14.1-inch M9165B/A
Apple iBook G4 14.1-inch M9165CH/A
Apple iBook G4 14.1-inch M9165J/A 

97fishmt:
Hey birdhouse,

It's time to build a lawnmower generator out of your Fanuc motor.

You can use the C-60 for regulation but you still have to keep an eye
on it.

You'll be happier with a better motor for the turbine when you find
it anyway. 

Or find a 24 volt alternator,  I use a 48 volt  G.E. out of a dozer, got
it for $50. 

The servo's for 24 volt charging are getting harder to get a deal on
or I'd make a trip down to see ya.  :)

Mike

birdhouse:
mike-
yea, that'll be a long term solution.  i "think" i've got a free 3.5hp briggs to play with.  i think semi alternators are all 24v...

at this point though, a possible $60 for a 15 amp charger sounds like the go for me!


adam

oztules:
The cheapest most useful devices I have found for the money are these things.

http://www.ebay.com.au/itm/New-24V-15A-360W-Switch-Power-200-240V-Supply-Driver-LED-Strip-light-Display-/120799021110?pt=AU_B_I_Electrical_Test_Equipment&hash=item1c202ec836

http://www.ebay.com.au/itm/350W-24V-14-6A-Regulated-Switching-Power-Supply-/170607332827?pt=LH_DefaultDomain_0&hash=item27b8fd4ddb

They are nominally 24v with adjustable voltage control on the output.... if you change the series resistor going to the trimmer pot, you can push it up a few more volts without danger. These ones go up to 26.4 or thereabouts, it's no problem extending this a bit.

There are 27volt versions, but more rare/dearer. (26-31v)

They are switch mode power supplies. You can dial up your voltage... but most importantly, for battery charging you will have terrible power factor... and these things have internal power factor correction, and so leave your alternator with much better control (less current in the windings for the same actual power output)

or

Grab an old microwave oven transformer, haul out the secondary, pull out the shunts (metal plates between the primary and the secondary) and rewind the secondary with heavy wire.
 I did one a long time ago here:




good for about 20A or more@42v.. or 40A@22v

This transformer is wound for saturation, so best run with a decent AC capacitor in series to stop it from heating up, and keep the low batt voltage surge to reasonable levels..



..............oztules

birdhouse:
thanks oz!

i saw those LED power units while hunting.  i was concerned on weather they'd go higher than 24-25 volts, but sounds like they're a go, especially if you mod them. 

i hope you don't mind if i PM ya once i get it, cause i'm really kinda lost on replacing a resistor with a different value.  i mean, i understand what your saying but would have no idea what value to use, or where to find this particular resistor within the unit. 

adam

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