I'm setting up an Outback GVFX3648 grid tie inverter. I don't plan on using all of it's capabilities such as battery backup. I will however need a small battery bank for it to work properly feeding the grid with my DC input.
I need a 48v battery bank, but don't need a bunch of capacity, just enough for the inverter to be happy.
What does anyone suggest for a cost/value selection?
I'd get 4 of the cheapest car batteries you can find. You can find them new for around $50. I would start with a matched set.
I'm building an electric ATV and plan on buying three "cheapski" size matching batteries just to adjust for size and the testing of everything. The trojans are going to set me back about $200 each while the beginner set will be about that much for all three.
Just to digress a bit. What is your DC source? Have you ran this concept past the utilitity? An engineer? Outback?
Casey
http://www.windsun.com/Batteries/Battery_FAQ.htm
I have been doing some research into the same thing. The above link gives lots of different scenarios and pros and cons to base a decision on. If you are not going to be drawing them down very far the 4 auto batteries is a quick and painless way of getting everything working but it is not much capacity and they wont last long if you are cycling them down deep and often. The next jump up in seriousness is to the golf car 6v deep cycle batteries but you need 8 of them. I just priced them today at a preliminary price in Canada of $188.00 each. That is about the minimum sized units used in most serious sized setups. If you want to go king of the road the Surrette 6cs25ps 1156ahr ones are $1575.00 a shot!
Sams Club in Tulsa had golf cart batteries for $69 this past Saturday. They had 3 pallets full, but were going quickly. Maybe not the best, but a decent start.
Terry
Tie your system to the phone line. The telco keeps that alive with 48 VDC with a humongous battery plant at the central office. In the lingo of the trade that is called 'talk battery'. Likely not enough current available though to do what you need.
Quote from: Tom on November 16, 2010, 05:56:55 PM
I'd get 4 of the cheapest car batteries you can find. You can find them new for around $50. I would start with a matched set.
I'd say use regular "marine" batteries. They are not true deep cycle batteries, but they are made in mass, and costs are much less than true deep cycle, and will last longer than starting batteries.
if the system design only calls for the batteries to be a buffer and the batteries will never see more than 5-10% used off the top of them, then the automotive battery can be the most effective and biggest bang for the buck,
the problem is the desire to deep cycle them will lead to rapid failure, often times in less than 50 cycles and sometimes much less.
if you can either automate the process to assure that they are never really cycled, or can discipline yourself then perhaps a car battery would be a good alternative.
car batteries last for years in very hostile conditions, hot underhood temps, often poorly charged, vibration and dirty, but they hardly ever get cycled over about the top ten percent of capacity.
that ain't much to play with, but it can be a large amount of power over a very short interval useful for starting heavy loads.
in a very shallow cycle situation, it might be that the car battery holds up better and longer than a true deep cycle that never gets an opportunity to get its electrolyte mixed well, stratifies and erodes the plates prematurely. a good car battery can last 8 or more years under average conditions, and it might be a very expensive deep cycle that is warranted for 10 doesn't make it as far.
something to consider fwiw
bob g
Quote from: rcavictim on November 16, 2010, 09:48:15 PM
Tie your system to the phone line. The telco keeps that alive with 48 VDC with a humongous battery plant at the central office. In the lingo of the trade that is called 'talk battery'. Likely not enough current available though to do what you need.
Now that is
just plain sneaky! They dont need to "tap" your phone line; they need to put a meter on it! ;D
Is there anyone here with an outback that can answer a question that I haven't seen in all of my readings......?
When does the inverter decide to feed the grid, and how much does it pull to do so?
How does it know when I'm feeding my battery bank from the sun (or other source) and know when to stop drawing power?
The manuals don't even mention it.
i don't know for sure, however my bet is they use a setpoint on the dc buss to determine when and how much to feed the grid.
for instance if they use a setpoint of 12.9 volts or so, then the grid tie will technically not draw anything from the batteries, and only draw from the dc buss when the voltage exceeds 12.9 volts.
aside from that there is likely some programming to be done, or it does it on the fly, so that it samples then loads the buss lightly, resamples and if the dc buss still exceeds the setpoint then it loads the buss more, resamples rinse wash and repeat until it samples
and finds that the setpoint has been breached at which point it would reduce the loading on the buss to get back up over the setpoint
value. this could all be done in milliseconds and there is likely some sort of algorithm they use to speed up the process.
thats how i would do it if i were them
bob g
Quote from: bschwartz on November 17, 2010, 07:15:16 AM
Is there anyone here with an outback that can answer a question that I haven't seen in all of my readings......?
When does the inverter decide to feed the grid, and how much does it pull to do so?
How does it know when I'm feeding my battery bank from the sun (or other source) and know when to stop drawing power?
The manuals don't even mention it.
I think with outback, you need a HUB and a MATE to get into the menus. XW's need a SCP (system control panel) they don't let you just access your expensive box, you need more boxes to do that. :-[
I've got a couple of those inverters and Mike is correct you'll need at least a Mate for the programming interface. I don't think you'll need a hub unless you have more than 1 outback device. Although my system is off grid I've read that the sell feature is triggered by the dc buss voltage. The Mate also gives you access to the internal metering in the inverter so you can see how much you are selling too.
Tom, do they NEED to be programmed, or will it work with basic defaults. It would really suck to need to spend another $500 just to make this thing do what it is supposed to do!!!
Hi bschwartz,
QuoteJust to digress a bit. What is your DC source? Have you ran this concept past the utilitity? An engineer? Outback?
Casey
Casey
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 (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.
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
I wonder if anyone can beat the Costco warranty? Or bang per buck?
Casey
Quote from: LowGear on November 18, 2010, 10:01:56 AM
I wonder if anyone can beat the Costco warranty? Or bang per buck?
Casey
How long is their warranty?
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.
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.
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.
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.
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.
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.....
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.
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.
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?
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!!
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.
It's worth a shot at this point. Now it is just figuring out how to best rectify the single phase 60v AC so as to not release the magic smoke from the Outback......... I just liked the power supply because I could maintain the 120/240 from the ST head without any mods, and I could always switch off loads directly from it when needed (yes, I could put in switches, relays, breakers etc. to go back and forth....) :(
In reading bob_g's suggestion on how to wire a single large rectifier it seemed quite complicated due to trying to polarize the coils. My thought, and I'm thinking of doing similar to feed a Outback MX60, is to use a separate smaller rectifiers for each of the 4 poles and buss the DC outputs together. Pretty easy to tell the polarity at that point. ;)
can the rectified dc be fed unfiltered into the mx60?
I have four evergreen 210W 12v panels (not up yet) but not a charge controller yet....... hmmm what should I get?
Tom,
it would be far easier and probably less costly to do as you say, rectify each individually then connect them in parallel
easy because it is easy to check the polarity of a rectified coil and cheaper because low power rectifiers are cheaper
than high power ones.
and if you lose a rectifier you don't lose all capability as you would if you connected all the AC coils in parallel and rectified
the product.
bob g
would 4 of these do the job?
http://cgi.ebay.com/Motorola-MDA3502-35A-200V-bridge-rectifier-/400023927439?pt=LH_DefaultDomain_0&hash=item5d2348ba8f#ht_500wt_949
Those rectifiers look like they would do the job. You will be seeing about 15a at 60v at best so those are well within spec.
As for feeding the mx60, I don't know if it would work. The closest I've seen is the output of an st5 through a transformer down to around 80v and rectified to a mx60. I believe the core of the transformer probably did provide some buffering though. Without a scope no real way to tell for sure.
It sure would be nice to have a 3 stage, temp compensated charge controller that would regulate via the field current on a modified st5 for charging 48 volt battery banks. Probably could even sell a few of them to off-gridders like my self.
OK!
I finally got to Costco. Their deep cycle marine batteries are a bout 70 and come with a standard 12 month replacement or 36 month prorated refund warranty. Costco labeled them "group 14" but they looked very "group 24" to me. They will probably be my break-in and test batteries on the converted Polaris ATV. The equivalent Trojan "pretty damn good" units are about $200.
Casey
I bought a new battery and returned dead one to Costco today. The Costco battery failed after six years of service! Can you believe it, only six years! ;) They gave me a $9.56 core rebate for it. What a great deal.
Casey
QuoteUnfortunately, 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!!!
Hey Brett, I'm a little late here: how did you figure it out? From experience w/ my VFX3648 in the past few weeks, there is an option where you can limit the amperage when it is in charging mode back to the batteries. I know you're using a 48 V power supply to charge the batteries with, and there's probably no way to limit that amperage, but there may be an option to limit how much current the VFX sends into the grid. I've thought of using power supplies for charging, but if there's no way of limiting the current all you'll get is a stalled 'roid. At one time we discussed using a Xantrex C40 charge controller. It's a PVM unit that does max 40 A @ 48 V DC -- about 2000 watts. That would be a satisfactory load for a 6/1. They aren't that expensive. $140 new at altestore.com, cheaper used. In my case, if changing the field current on the ST head doesn't work, then I may try the C40.
Quotecan the rectified dc be fed unfiltered into the mx60?
This was discussed on another thread since, but I might as well answer it here too. It won't work. About a year ago, Geno tried it with some success. It charged but after a while the screen on his MX60 got garbled. It fixed after he rebooted it. About a month or two ago I tried it unfiltered into a MX80 instead of MX60. (They're pretty much the same.) The MX80 locked onto the rectified DC, then dropped, and cycled quickly like this over and over. For anyone trying this, at least use a filter like a coil choke, or large capacitor, or both in an LC circuit to smooth the ripple.
Didn't mean to divert the thread but I saw some unanswered questions... So, Casey, what are you using the battery for?
Quote from: LowGear on December 19, 2010, 01:56:16 AM
I bought a new battery and returned dead one to Costco today. The Costco battery failed after six years of service! Can you believe it, only six years! ;) They gave me a $9.56 core rebate for it. What a great deal.
Casey
Not bad, what kind of service was the battery used in?
The battery was used in a Tacoma 4 cylinder. I'm currently going for every light to be "ON" on the dash. I've got brakes, engine and airbags covered so far. Oh, and emergency brake most of the time.
Casey