cheap (I mean inexpensive) batteries

[Tom Reed]

Well the good news is you can get a Mate on Ebay for $260 http://cgi.ebay.com/OutBack-Power-MATE-System-Controller-Version-4-x-NEW-/390259661604

IIRC they will invert from default settings but probably not sell power.

[BioHazard]

Sears sells a 115ah Die Hard 12v deep cycle for $120 with a 1 year free replacement and 30 month pro rated warranty. I'm thinking about getting a set of 4 for my truck for inverter use. For me it's all about the warranty, I don't care what type of fancy battery you buy, it might die tomarrow for no good reason.

http://www.sears.com/shc/s/p_10153_12605_02827582000P?sid=IDx20070921x00003a&ci_src=14110944&ci_sku=02827582000P

[LowGear]

I wonder if anyone can beat the Costco warranty?  Or bang per buck?

Casey

[BioHazard]

I wonder if anyone can beat the Costco warranty?  Or bang per buck?

Casey

How long is their warranty?

[cujet]

Corporate jet aircraft are often fit with 24v Sealed Lead Acid batteries (as an effective replacement for expensive NiCad's). We, in the industry often change the batteries every year, or year and a half.

If you are near an airport with a corporate jet maintenance facility, you may be able to get your hands on some of these batteries. I have a bunch of them. They are 40 or 44 AH 20 hour rating batteries.

However, we all know the batteries age rapidly. They will easily exceed the AH rating when new, and will meet it after 2 years of normal use, by design.

[bschwartz]

Well, as they are basically a buffer for the incoming DC from the solar panels, or listeroid, I ended up getting some el-cheapo Sam's Club 'marine' batteries.  At $62 each (I got 4), it was hard to pass up.  If I ever end up needing real storage, I'll look into something with greater capacity and better performance curves.  Now I need for the Outback mate to arrive so i can see what this thing does when connected.

Thanks for your suggestions.  Although I went for lowest cost now, I may look back on this thread in the future for your wise words.

[cujet]

I have 2 golf carts with those sams club batteries. One gets daily use at the international airport as a runabout. The other gets only occasional use, maybe once a month, but drives much farther distances.

The one with daily use gets charged when needed, or on weekends. It's batteries have lasted very well, and it still retains 100% performance.

The one with occasional, but deep cycle use is on it's 3rd set of batteries.

Not sure what conclusion you can draw for your system. However, it seems clear to me that the type and number of charge/discharge cycles play a huge role.

[bschwartz]

HUGE SUCCESS TODAY!!!!!  I connected the 4 batteries in series (48V), hooked up the 3KW 48V (from 240 AC) power supply, and connected them to the GVFX3648.  I turned on grid power to the Outback, turned on the power supply, connected the batteries, and everything worked beautifully!!!!  Sort of.....
The Outback recognized the grid, and the battery bank.  It takes 5 minutes until it will sell to the grid.  Once it decided to do that, it just started sucking all the juice it could get.  It actually worked a little too well.  The power supply would put out all the Outback would take, but the power supply was being run from the ST-5 and my 6/1.  It drew too much power and nearly stalled the engine till I disconnected it.  Now I need my Outback mate to arrive, so I can see if I can program the inverter to limit how much power it tries to sell back to the grid.  I think if I can tell it to pull 2000-2500 watts, that would be an ideal draw on the engine.

[Tom Reed]

Great news! Haven't messed with the sell features of my outbacks, but it is there. I think the way you will end up needing to go is to use the voltage limits to set how much current is drawn out of the engine.

[bschwartz]

Tom,

I've been trying to read the PDFs from outback to figure out how to program this thing...... the instructions stink!!!

Once I get the mate, I will take any advice on how to program it.

How will setting a voltage change the current?  That could be a killer for my setup, as the output of the power supply is stable under load, so a voltage drop won't occur until after it's overloaded.....

[Tom Reed]

Well I'm think of how a pv panel behaves and what the inverter has to do to deal with that. The strategy is for the inverter to first charge and maintain battery voltage from the pv source and then sell any extra to the utility company. Ok I just check my inverters and under the advanced menu page 4 is the sell menu and the only real selection here is battery voltage. Strangely mine is set ridiculously low at 47.2 volts.

Here's something to try before your mate gets here, back of on the governor setting, I'm betting that as you do so and the voltage output from your st5 drops to near the point, the inverter will back off on the sell current causing the load to decrease st5. If that works then when the mate arrives, you can start to bump up the sell voltage, within reason, and turn up the governor to achieve the running rpm on the listeroid that you want.

[bschwartz]

Tom, the problem is that I'm using a real 48V power supply.  It is a 240V AC to 48V DC unit.
It isn't affected by engine speed.

[Tom Reed]

Oh, then since the 48vdc output is fixed then when the Mate arrives try upping the sell voltage by 1/10th of a volt until the load decreases on the engine. You know the batteries will make a great buffer to smooth the inverted ST5 current. The reason I mention this is that 48vdc is a bit low for a float voltage for your battery bank. 52-56vdc would be much better, depending what the mfgr recommends. What is the actual output of your power supply? And is it adjustable?

[bschwartz]

Tom,
"the batteries will make a great buffer to smooth the inverted ST5 current."
The ST current isn't inverted to the batteries.


The setup is as follows.

6/1 engine turns ST-5
ST-5 produces 240V AC
240V AC powers kepco 48V DC power supply (adjustable up to about 59V) up to 60A
Power supply paralleled with 4 12v batteries in series (48V)
Batteries/power supply connected to DC input of Outback

What ever voltage I set the PS to, it keeps.

If I set it to 56 volts, it will hold that (even under load) very closely.

If I set the sell voltage to 56v, once everything hits that mark, it (The Outback) will start drawing from the power supply.  The power supply will keep drawing from the ST to keep up with the load.

Unfortunately, the power supply, and the draw from the Outback are greater than what the 6/1 can provide.  If there is no way to limit the current (total wattage) draw from the Outback, then this whole thing may be a HUGE BUST!!!

I am CLOSE, as the power supply will draw up to 3300 watts max, but with losses, my 6/1 ST-5 will only provide about 3000 watts.  It seems to be just over that tipping point of available power.  AARGHHHH!!

[Tom Reed]

Some times I wish my writing skills were better. I understand your setup the problem is the inverter is designed to work with PV panels which will drop voltage when overloaded. Your power supply is designed to maintain voltage so it doesn't seem to me like it would be a good way to go, besides the inefficiencies added to the system. IIRC you pulled all 4 windings out of your ST5. Since you've already done the "hard" part, they could just be wired in parallel and rectified. Now you would have a variable voltage source that will work well with the inverter.