It's probably my cheap Outback equipment the display may say Absorb, but the shunts say it's still in Bulk and the amps haven't started to drop, so yeah there could be some difference. There is probably some saturation and equalization time as the voltage stops rising and the current starts to drop. How about a new term, Declining Current Phase is in PWM. My Re-bulk is pretty high, so maybe I never go back into bulk.
Help with batttery system
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20 amps x 12 volts = ???? Watts
25 amps x 12 volts = ???? Watts
a 20 amp MPPT controller can only convert to 20 amps at battery voltage.
Answer your own questions and you will understand a lot battery. I am giving you the tools you need.
Watts = Volts x Amps = Current x Current x Resistance
Watt Hours = Watts x Hours = Battery Voltage x Amp Hours
Voltage = Current x Resistance = Power / Current
MPPT Output Current = Panel Wattage / Battery Voltage
Put it all together and you have Ohm's Law.
MSEE, PEComment
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Me i have no control. I just speak loudly to warn people, and hopefully embarrass the offender so much they just leave in shame. But i will comply with your request. Ban me if you like, I do not care, but I take what I have contributed with me. You get stuck with Willy's as a replacement.MSEE, PEComment
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Willy T.
YOU brought up the first mention of 4/O cable
ya'all are now warned.
LKruper - with your lister gensets,
with the older diesels , you have to be cautious of "Wet Stacking" if you run less than 60% load. Newer gensets don't have that much of a problem lightly loaded.
Your ST heads, are they internally wired in parallel for 120VAC, or for 240VAC ? They are sensitive to load imbalance if wired for 240, and you only load one side, the windings really growl and groan. You may want to consider 2, 120VAC chargers, one on each leg of the generator, to keep loads balanced.
see http://www.utterpower.com/genhead.htm for the mod
http://cgg1.com/index_htm_files/ST%20Manual-42013.pdf for the manual
I run a CS-6 with a ST-5 head @ 240VAC and use it to both run loads and the integral charger in my inverter (XW-6048) which also does load balancing for me too. Because of loading limits, I limit my charging to 30A to prevent overloading my engine.
30A @ 60V =1800w plus my base loads, and I'm at 1,400' elevation.Comment
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You tell me. 300 watts / 12 volts = ????
20 amps x 12 volts = ???? Watts
25 amps x 12 volts = ???? Watts
a 20 amp MPPT controller can only convert to 20 amps at battery voltage.
Answer your own questions and you will understand a lot battery. I am giving you the tools you need.
Watts = Volts x Amps = Current x Current x Resistance
Watt Hours = Watts x Hours = Battery Voltage x Amp Hours
Voltage = Current x Resistance = Power / Current
MPPT Output Current = Panel Wattage / Battery Voltage
Put it all together and you have Ohm's Law.
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I had one good instructor in college I really liked. He said don't ask me questions, figure it out yourself. He said he was not paid to be an answer man or teacher, I am here to instruct you how to figure it out yourself. He went on to say: If you want answers and ideology, go see a professor who has never done anything, that is why they teach and preach. I never forgot that and try to live by it. Even one year I taught musheads students in Jr College. It separated the students from the slackers. You passed the test.MSEE, PEComment
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Let's get some simple math out of the way and help you understand. It is 5th grade math and super easy
Starting with Amp Hours = Amps x Hours. Told you it was hard.
From that equation then you know:
Amps = Amp Hours / Hours
Hours = Amp Hours / Amps
Using simple numbers let's say you have a 100 AH battery. You want to discharge it at 10 amps. How many hours does it take to discharge it. 100 AH / 10 A = 10 Hours.
Want to charge that battery from completely discharged with a 10 amp charger. How many hours will it take. 100 AH / 10 A = 10 Hours.
How many Amps can that same battery last with a 5 Hours discharge rate? 100 AH / 5 H = 20 Amps
Unfortunately life is not that simple. Batteries are not 100% efficient and Mr Peukert Law gets in the way. Not to worry what is above gets you the idea.
Next problem you run into is batteries have minimum and maximum charge rates. A FLA battery minimum is C/12 and maximum is C/8 generically. C = the battery AH capacity at the 20 Hour discharge rate. So those 225 AH batteries need at least a 225 AH / 12 H = 18.75 amps. Just call it 15 is close enough. The maximum is 225 AH / 8 H = 28.125 amps. Just call it 30 amps is close enough. So you now know you need something in the 15 to 30 amps. But there is a Gotcha. It you go with 15 and want to use power while charging, you are robbing the battery of charge current. If your load is 30 amps and you have a 15 amp charger, you are still discharging your battery at 15 amps. Gotcha!
On the Flip Side Batteries have a Maximum Discharge current they can provide otherwise their voltage will sag to far and cause unnecessary Low Voltage Disconnect built into all Inverters. For standard FLA battery that is about C/8 or 30 amps on a 225 AH battery. So if your limit is 30 amps limits how large of an Inverter you can run. So you want to run 24 volts x 30 amps = 720 watts. Not a good match for a 1000 watt Inverter.
Don't cuss there is a work around. Use a hybrid FLA or a more expensive AGM battery. Buy Golf Cart FLA batteries, as they are Hybrids. A Golf Cart battery can handle C/4 Discharge currents so a 225 AH battery can supply up to 225 / 4 = 56.25 amps, just call it 60 amps. At 24 volts x 60 amps can handle a 1500 watt Inverter so a 1000 watt 24 volt Inverter is no problem.
This brings us back to a battery charger issue again. You do not need a 3-Stage Battery Charger for Emergency Back Up. You do not even want one for that application. You want a FLOAT CHARGER of the appropriate Amperage Capacity. You will leave it plugged into commercial AC keeping the batteries fully charged waiting to be used. You want it to be as large as a standard 120 VAC wall socket can supply and your generator. a 120 VAC circuit in your home can supply 1500 watts continuously. So for a 24 volt battery charger you are looking at a 60 Amp 24 volt charger.
Now just go over what we just did and look at how the pieces fit together in harmony.
You are looking at needing a:
1800 watt genny. check
24 volt 60 amps FLOAT CHARGER. Check
4- 6 volt 225 AH Golf Cart Batteries wired in series. Check
1000 Watt TSW Inverter. Check
Fits like a custom tailored shirt made with Warm Fuzzy.
Is it always true that the charge rate and discharge rate are the same?Comment
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No Sir. There are just general rules. Golf Cart batteries are not what you would really call Deep Cycle Batteries. Close but slightly different different in construction and application. Great example is the Trojan T-105 and T-105RE. The 105 is a pure Golf Cart battery of 6 volts @ 225 AH in a GC2 case. The 105RE is a pure Deep Cycle 6 volt @ 225 AH in the exact same GC2 case. Side by Side you cannot tell the difference. When you go to pick up the T- 105RE you will know the difference because it is 10% heavier than the T-105. It has more lead in it. ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ The T-105 is recommended to be charged the same as the 105RE of 10 to 13% of C which is 22 to 30 amps. However the Golf Cart version has lower internal resistance, and thus can be discharged at higher rates with Less voltage loss. You can discharge them both at say C2 or 110 amps for an hour until discharged. The difference is the T-105 will deliver the 100 amps at a higher voltage of say 4 volts while the RE would be down to 3 volts. -------------------------------------------------------------------------------------------------------------------------------- You can charge any lead acid battery at any charge rate you want. On the high end as much current as the battery will accept without going above the gassing voltage of around 2.4 vpc. The higher the internal resistance of the battery, the lower current is going to be.MSEE, PEComment
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No Sir. There are just general rules. Golf Cart batteries are not what you would really call Deep Cycle Batteries. Close but slightly different different in construction and application. Great example is the Trojan T-105 and T-105RE. The 105 is a pure Golf Cart battery of 6 volts @ 225 AH in a GC2 case. The 105RE is a pure Deep Cycle 6 volt @ 225 AH in the exact same GC2 case. Side by Side you cannot tell the difference. When you go to pick up the T- 105RE you will know the difference because it is 10% heavier than the T-105. It has more lead in it. ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ The T-105 is recommended to be charged the same as the 105RE of 10 to 13% of C which is 22 to 30 amps. However the Golf Cart version has lower internal resistance, and thus can be discharged at higher rates with Less voltage loss. You can discharge them both at say C2 or 110 amps for an hour until discharged. The difference is the T-105 will deliver the 100 amps at a higher voltage of say 4 volts while the RE would be down to 3 volts. -------------------------------------------------------------------------------------------------------------------------------- You can charge any lead acid battery at any charge rate you want. On the high end as much current as the battery will accept without going above the gassing voltage of around 2.4 vpc. The higher the internal resistance of the battery, the lower current is going to be.
Here is my situation. I just had my Reliance 10-circuit transfer switch installed and am in the process of testing my Generac ix 2000 inverter generator. If it handles the surge of my Energy Star 14.5 Frigidaire and my small Suppenton 3.2 then I don't need anything else, but if it does not run all my loads plus the surge then here is plan b:
Power Normal: Grid -> Charger -> Batteries -> PSW Inverter (Off)
Power Out: Generator -> Charger -> Batteries -> PSW Inverter (On) -> Transfer Switch -> max 177 w/h load + surges
I am hoping that the batteries will handle the surge if my generator cannot, that I can also run the generator in Eco mode to save gas and also that the generator can both charge the batteries and run my loads at the same time. (I am considering 2 Golf Cart batteries, Progressive Dynamics 12v 70 Amp charger and Samlex 1000 (2000 surge) pure sine wave inverter). This system will only be used if the power goes out and we are at the cabin or when I test the system to exercise the generator and/or test the batteries. I estimate that my batteries will carry my load for about 5 hours if I do not conserve(eg turn off one fridge) and keep the TV on 16 hours per day and might last the night if I do conserve. One goal is to not have to listen to the generator at night.
One thing I am also wondering is what effect does the fact that this charger apparently does not have temperature correction have on the life of the battery? Is this less important when the batteries spend most of their time in float?Comment
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Not something to worry about while charging on generator or really any charger in Bulk and Absorb modes. Temp compensation is something used in Float Mode Stand-By service applications where the batteries could set there for years doing nothing and remain on Float Charge. Solar Off-Grid is a daily cycle operation and a rare event you will see FLOAT MODE. Even if you do is not till late in the day, so you never spend any real time in Float. Only thing where you really use temperature is when you measure Specific Gravity so you can make the Correction to read your SOC. 99% of the time, your Specific Gravity is going to be low. If you Specific Gravity is low all the time means it makes no difference what voltage you set your controllers too because you will never get fully charged up unless you use a generator.--------------------------------------------------------------------------------------------- Sounds like your system is grossly undersized. If that is a true statement, then voltage set points is a moot point for you because you can never get there. ------------------------------------------------------------------Kind of like being a parent with a 5 year old kid. You notice one day the kid jumping up and down and ask what he is doing. He answers trying to jump over the moon. You just turn away and let them jump. Eventually they will get tired and quit, and going no where fast.MSEE, PEComment
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Not something to worry about while charging on generator or really any charger in Bulk and Absorb modes. Temp compensation is something used in Float Mode Stand-By service applications where the batteries could set there for years doing nothing and remain on Float Charge. Solar Off-Grid is a daily cycle operation and a rare event you will see FLOAT MODE. Even if you do is not till late in the day, so you never spend any real time in Float. Only thing where you really use temperature is when you measure Specific Gravity so you can make the Correction to read your SOC. 99% of the time, your Specific Gravity is going to be low. If you Specific Gravity is low all the time means it makes no difference what voltage you set your controllers too because you will never get fully charged up unless you use a generator.--------------------------------------------------------------------------------------------- Sounds like your system is grossly undersized. If that is a true statement, then voltage set points is a moot point for you because you can never get there. ------------------------------------------------------------------Kind of like being a parent with a 5 year old kid. You notice one day the kid jumping up and down and ask what he is doing. He answers trying to jump over the moon. You just turn away and let them jump. Eventually they will get tired and quit, and going no where fast.
The battery system is undersized because all I want from it is to provide surge capabilities for the fridge (if I find it is necessary with my generator) and to allow for a few hours of sleep time at night without listening to the generator.
At this time I don't have any plans for solar. That would be phase III, and the only purpose would be to prepare for an emergency that lasts long enough to exhaust my gasoline supplies (1-2 weeks).Comment
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OK here is my take. You need temp compensation on whatever charger the batteries are normally charged from. In a solar system that would be the Solar Charge Controller. --------------------------------------------------------------------------------------------------------------------------------------------------------------------- However when charged from a genny, you do not need expensive 3-stage chargers with temp comp. Complete waste of money and only slows things down. When you charge on a generator, there is only a couple of good reasons to do so. 1. woul dbe you have gone a couple of days without Sun. 2. Monthly EQ maintenance. ----------------------------------------------------------------------------------------------------------------------- Either way you are looking to get to fully charged as quick as possible. Last thing you want is a long Absorb aka Float saturation charge. You want to set your charger to a high voltage to fore it into Constant Current until the cell voltage is near 2.5 to 2.6 volts per cell, then terminate the charge. This is known as Fast Charge. --------------------------------------------------------------------------------------------------------------------------------- Fast Charge is a Constant Current until you hit a target voltage, and then terminate. So when shopping for a charger to be used on a generator there are a few things you are looking for. Power Factor Correction, CC/CV mode of operation. Adjustable set voltage of 2.65 vpc or 16 volts on a 12 volt battery, and as high as a current as your batteries and genny can handle. That higher voltage and current is going to be the most effective at dissolving the soft lead sulfate crystals on the plates and minimize charge time. Remember Pb batteries live on a knife edge to fall off of. One side is Sulfation (too low of voltage), the other is Corrosion (too high of a voltage) . You want to live on the Corrosion side of town for cycle applications. For Float Service you want to do the Balance act on the knife edge using temp comp. Maintenance is always on the Corrosion side.MSEE, PEComment
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