Backyard Aquaponics
A place to discuss aquaponics

You could take a gamble on this little guy:

http://www.ebay.com.au/itm/Redarc-BCDC-1206-3-STAGE-12V-DC-DC-battery-charger-/160782753733?pt=AU_Car_Parts_Accessories&hash=item256f661fc5#ht_603wt_1398

Wont do a high enough current though.

Very few solar chargers, particularly cheaper ones, boost upwards to the battery voltage.

Fair enough. Hope they dont just burn the power off :S

Just make one BW You know how to use PWM on yer picaxe

Nope, its just sits there at less than battery voltage, with no current flowing at all.

Sorry, I meant the 22v panel

At less than battery voltage I suppose that the panel sees an open circuit. Such a waste...

havnt read this whole thread yet so maybe its already been answered.....but i have built and installed high end mega expensive car audio stuff....... (audio systems $20+ a pop) 12v batteries like up to 14.4V input. and that is the "peak" ideal charging voltage.

lead acid arent like nicad or other rechargeable batteries. led acid will only accept as many amps as they need. so you can have a system that can put out 200 amps at 14.4V but if the battery dosnt need that many amps it just wont accept it. one of the first upgrades in mega audio setups is to upgrade the alternator to one that can pump out double the amps that the car was designed to need.

many car regulators are set slightly lower than 14.4v, down into the 13's, caus above 14.4 you blow fuses and bulbs and all sorts of things and usually regs in cars arent super accurate. so a reg set to 13.8v may actually send through far more than 14v

Sure.

Want to buy a used fish feeder?

Hmmmm tempting...

is it metric?

No, but it has over-unity, quantum-harmonic tech, and I offer a 99 year money back guarantee that you will see no decline in performance from the first day you install it.

I can give you performance stats from the Californian Institute Of Scientitians if you don't believe me. It's extremely well documented tech. (almost 60% of all new patent applications have been employing it since the internet went domestic)

lol @ BW

[quote="Privatteer"]That charger rsevs3 linked to I am pretty sure won't work.
Its auto switch between 12 and 24v. You have a 24v panel and so far a 12v battery.
Most likely its going to try and charge your battery to 26v!

Normally you would use a panel with a Vmax of about 19v for a 12v system. You are going to have to look for a charger that can handle an input up to 37v but charge a 12v battery.
I'm not aware of any that do this.

Edit:
OK perhaps not a charger, but this will probably do you.
Most regulators like that put out 13.8v even tho its listed as 12v. So if it does it will float charge your battery without issues.[/quote

What you want is called a DC/DC buck controller. It is a small circuit board (about $6 on ebay). This will regulate your 37V down to 14.4v before sending it to your solar charge controller. They have a small set screw on the IC that allows you to regulate the output to what you require. just hook up you panel to it, attach a multimeter to the output and dial the screw in or out till you get your 14.4 v output.

Similarly there are also buck/boost controllers that dial your supply up or down to what you want, but if your are converting upward the current will not boost as well. Ie. if you have 6v at 0.5a boosting to 12v you still only get 0.5amps. Or at least that's how it was explained to me by an electronics guru I know. I use a buck controller for my vertical wind turbine so I could do basically the same thing your looking to do as it was putting out up to 27V at times. I then wired the dump load from the charger controller with a diode to prevent backflow of energy to my generator to slow or stop it when the batteries are fully charged. I had help from my friend to get this set up but its worked like a charm now for 6 months and I run 700w's off of my batteries for hours on end through a 1kw mod. sine wave inverter to power my PC Mind you we are near the ocean and almost always have enough of a breeze (5mph is all I need) to trickle charge my 500AH (10x 12v 50ah) battery bank.

This may be your best bet, i have one, use it to charge 12v batteries from a 24v panel. It also works up to 65v
http://jaycar.com.au/productView.asp?ID=MP3735
Also search eBay for MPPT and you will find some similar.

That sounds like just the thing I want.

I've found a few [MPPT] chargers on ebay, but I'm never sure if I can select 12 or 24 volts, or if it detects 24 volts from the solar panel and presumes a 24 volt battery. Domr of them say they are auto switching. I have no idea what that means. I've asked a few dealers on ebay and they dont seem interested in replying. Perhaps there is a language issue.

And is there by any chance room for a second input? Given I still have the mast from my little boat from when it was a racing cat, I was thinking of making a small wind turbine just to make sure I have enough power to keep the trolling motor running flat out (walking pace)

If it's up to 65 volts, I can probably just tie the solar panel and wind turbine together.

Will it matter if the input voltage swings wildly all over the shop?