Discussion in 'Off Grid' started by Two Track, Oct 25, 2012.
How far is ok to drain the battery's on a regular basis. Don't want to damage them.
DEEP CYCLE BATTERY ???
How many discharge cycles do want from your batteries ?
The smaller the depth-of-discharge then you get more cycles.
The deeper the depth-of-discharge then you get fewer cycles.
Typically, Deep Cycle batteries will die in 4 - 8 years, regardless, from age.
DOD (Depth-Of-Discharge) ...
You can get about 2,000 Cycles at 25% Depth Of Discharge (75% charge remaining)
You can get about 1,000 Cycles at 50% Depth Of Discharge (50% charge remaining)
You can get about 750 Cycles at 75% Depth Of Discharge (25% charge remaining)
Depth-Of-Discharge is accurately measured by Specific Gravity, NOT by voltage.
If you want the batteries to last 6 years (average) and you discharge batteries every night (365 days per year) then you need 2,200 discharges ( 365 days per year x 6 years ) therefore the average is only 20% DOD each night. For each night that you have a 40% DOD then you can offset with a day of 0% discharge.
NOTE: The TOTAL Watt-Hours delivered by the Battery is nearly identical over 25% - 75% DOD range.
Slightly more Total Watt-Hours are delivered for shallow discharges - higher battery voltage.
Slightly less Total Watt-Hours are delivered for deeper discharges -lower battery voltage.
Recharge the battery, ASAP.
Do not leave discharged = sulphation = bad news.
Do NOT discharge more than 80% DOD (20% remaining) very often, if at all.
At 80% DOD every night then the batteries will fail in about 20 months because you consumed the Total Watt-Hours too quickly.
A battery will fail when:
1) Total Watt-Hours have been produced
2) 6 Years (+/- 2 years)
whichever occurs FIRST !
So your job is to size the battery and the load so that your average daily DOD is about 20% which causes the acummulated Watt-Hours produced to reach the batteries limit in about 6 years.
Yes deep cycle golf cart battery's
Thanks great info
Been taking them down to 30% going to try and keep it higher then that
Properly charging the Battery is just as important as proper discharging.
Do you have a 3-Stage charger with Equalization ?
Stage #1 = Bulk Charge or Constant Current Mode
Stage #2 = Absorption Charge or Constant Voltage Mode
Stage #3 = Float Charge or Reduced Constant Voltage Mode (compensates for normal internal discharge)
Also, periodically you will need to Equalize Charge (using Over-Voltage) , too.
Eventually, one or more cells will eventually develop a lower cell voltage.
Only an Equalization Charge can fix this.
Seems to take forever to charge my battery's. they charge
Fast sometimes then other times five six days go by and the battery charge stays at same level and there is plenty of solar and the last two days have had 35 to 40 mph winds from sandy storm. And nothing. Was wondering if an equalization would fix this or if I have another problem one battery is two years old but haven't used it much other two are brand new.
Have the C 60 charge controller
you shouldn't mix batteries. Maybe the older one is sulfated and suckin the life out of the newer batteries. Or.....maybe you just don't have enough experiance yet on what is Energy.
Ok I could try and isolate that older battery
And yes I don't have a lot experience, been learning though.
These are only my opinions so please do not take anything personall but i will try to layout a direction for you. For starters you may want to look up calculations on things you want to power when it comes to batteries. It is a simple system but their can be lots of problems if not calculated. So yes, to start with you could have battery problems but also not realizing what it takes to replenish them can also lead to other problems as well. NEOH has given an outstanding explination on batteries. Great job NEOH.
IMO you need to first decide why you are using RE, and batteries vs grid tie. Second you need to understand the system you will need so it supplies a useable amount of power for your needs. Once you decide what you want to power then you should proceed to sizing the system with expansion in mind. Use only indusrty standard components. Buying junk yeilds a low non productive system. Making your own power is not cheap. That's a fact. Do not try to invert the wheel. It will cost you triple. Keep it simple but use quality devices. Try to save up and buy the right components. You will be much happier you did. Been there done that. lol
For enegy calculations what ever you take from the bank has to be replensihed in time. If your bank holds "x" amount of power depending on your (energy collectors) solar/wind "x" amount of power to be put back in will take "x" amount of time. Knowing these factors will help decide how many panels, batteries, size of CC, wiring and how the system should be producing/working as a whole. A predicted calculation will let you know within reason if your system is problamatic. If you can built it then you should be able to trouble shoot it too.
So lets say you have all the same batteries (which is required hands down) at 12v and they are all 100 AH batteries deep cycle and a total of 4 in parallel keeping the voltage the same and increasing the amp hrs. That's all pos and all neg together.
(Series would be increasing the volts and keeping the amp hrs the same.)
(Series parallel does both. Used mainly for 24v and 48v systems). 12v systems are limited IMO even though I have one too.
Lets say you have a parallel system voltage at 12v (4) 12v batteries) x 100 ah = 400 ah of power.
Minus 50% depletion (see NEOH's post above on how this effects your batteries)
That's 200 Ah available.
200ah x 12v system voltage = 2,400 watt hrs
Now lets say you have (4) 100w solar panels
That's 400 watts minus 20% efffciancy factors from wiring, CC, batteries, inverter and such.
320 watts of solar times what ever your solar sun belt rating is. Lets say a 4
In perfect sun, 4 full sun hrs times 320 watts =1,280 WH (call it 1.3kw)
It would take at least 2-3 days of full perfect sun at 320 watts to replenish the bat bank.
The numbers I used are only "about" figures. This should give you an idea/direction to shoot for. Plug in any numbers you want to use the calculation to your system and location. You can not do this with wind because wind is to unpredictable. To give you and idea for using a 1000w wind turbine at 12v/24v you would need 2-3 days of non stop 18 MPH winds to make 1.3 kw at 320 watts. If the wind is sparatic (which it is) then even more days. I am not sure what your KwH rate is but 1.3 kw for most is about 15 cents however having a battery back up is priceless when it comes to grid failure provided you have enough power stored to use for at least 10 hrs as well as having the means or realization to replenish the power taken. Remeber if the power is out and the wind or slar is going it will let you run longer. What ever your reason for RE is and many people have different reasons other then just an ROI, I am glad to see you venturing in it.
I hope this helps
Thanks for the help I was not sure what it takes to fill the battery bank, thank everyone for the help on here don't mean to pain with all my questions, get Exiceded with this and trying to learn it inside and out and trying to get everything working right I am using the search box and reading as much as possible and has been priceless info on here. This thread has helped me the most and very much appreciate it .
Hey two track, looks like leamy explained it well. Now use the Internet to read and learn. Here's a pic of a old Hydrogen Appliances pma that I'm hacking so my Whirly Gig has something to do.
How do you know that you have been draining the batteries down only 30% ?
Do you have 12 volts batteries?
Are all batteries the same Amp-Hour rating?
What is the Amp-Hour rating of your batteries?
You have three 12 Volt batteries - 1 older and 2 newer ?
All three batteries are in parallel for a 12 Volt System?
What is the rated wattage for the Solar Panels? - You have good Sun?
What is Total rated wattage for Wind Turbine? - You have good Wind?
You need to use a hydrometer to check the charge on each cell.
Look for one (or more) cell(s) that has a different reading from the other cells in the same battery.
I have a meter on it
12 volt system for now
232 amp hours
One 12 volt is older but never used till now
Two 6 volt hook together to make 12 volt all hooked together in parll
175 watts in solar
500 watt turbine
Think I the issue is it takes longer then I thought to replish bank
232 amp hrs x 12v =2,784 watt hrs total
Running it down to 50% depletion 1,392 watt hrs available
1,392 watt hrs/ 175w of solar = 8 hrs of full sun light
With efficiancy factors it should take about 3-3.5 perfect sunny days at 4 hrs per day to replenish 1,392 watt hrs or 1.4 kw
Constant 20 MPH winds for about 6-7 hrs at a constant 250 watts with efficiantcy factors.
All round about numbers of coures but they should give you a clue in.
If you really want to make some power you would need about 1kw of solar and at least 1 kw of wind with at least 10 batteries. Hey we all started somewhere. Your system is a good stepping stone for some bigger goals. Keep saving and good luck
I hope this helps
You have a "meter" on it?
The Watt Meter in the C60 Charge Controller or other?
The good news is, the C60 is a three stage charger.
So, what is the Bulk Voltage setting and the Float Voltage setting?
Do you see the battery voltage hit and HOLD the Bulk Voltage
for at least one hour before dropping to the Float Voltage?
The above action indicates the batteries are being fully charged.
If not then you have a chronic under-charging condition.
Chronic under-charging will destroy your battery bank in one year or less.
How do you have the C60 Charge Mode configured?
Is it set as a "PV Charge" controller mode or a "Diversion" controller mode?
Do really have 6 - 7 hours of 20 mphs winds?
I think that happens maybe one day per year were I live.
So, you tell us ...
How many hours of full sun do your solar panels get each day? any shading issues?
175 watts x 4 hours = 700 watt-hours per day
So, you can energize a single 100 Watt bulb for 5.6 hours (not 7 hours) at 80% efficiency.
How many hours of 20mph winds (or lower) do you really get each day?
I have no idea but I am guessing you do not have that much wind ...
100 watts x 4 hours = 400 Watt-hours
So, you can burn another 100 Watt bulb for 3.2 hours (not 4 hours) at 80% efficency.
That is not very much power!
Do have any idea if you are actually generating 1,000 Watt-Hours per day via Solar+Wind?
Electric meter like you would use on a golf cart
Yes have seen it get to full charage then go down to float
Have it set to Diversion mode
No don't get that much wind
Don't have any shade issue but over all with Michigan weather yes It could be I am not making ad much as I think but I am learning
If you are consuming 20% to 30% of the batteries capacity every night then you should see the battery reach the Bulk Voltage the next day and then hold that voltage for 1 full hour (with declining amps) before the voltage drops to Float = Full Recharge.
Did you verify via the manufacturer what the proper Bulk Voltage and Float Voltage settings are for your specific battery ?
Bulk Voltage = 14.6v - 14.8v ?
Float Voltage = 13.4v ?
Do you have a Blocking Diode between the Battery and the Solar Panel?
NEOH, your moven right along here. Looks like Two Track will be ready for some type of CLEP test soon.
I might add since I’ve ruined at least a ton or two of batteries, charging is also very important. Those sunforce style solar chargers are battery killers. Trojan batteries have a different charging voltage than my US Batteries. My 24 volt batteries like to be charged at a temperature compensated 30 volts. That’s where a hydrometer comes into play. I bought by batteries from the same lot number, so they are all the same chemically and from the same litter. They are two years old now and still all read the same equal voltages. I can see the lead plates getting thinner.
Another lesson I learned is battery sulfating. There’s none of that white stuff on my battery plates. I have a 24 volt Battery Minder just for that, but I have since learned my Tri-Star mppt charges with PWM already. This is my first set of batteries where when I look in the battery fillers, the acid is crystal clear and the top of the plates are clean. No brown mud in there.
So until you get a better solar charger that has adjustable charging voltages, then get a grid powered battery charger to stir up that acid. Don’t forget, when the battery temperature gets to 32 degrees you might think you’re undercharged, but the hydrometer will tell you otherwise. Most things in life are based on a temperature between 72 and 80 degrees. Gas mileage drops at zero degrees, my energy star refrigerator runs constantly when it’s hot in the kitchen. The 12 year old fridge I replaced hardly runs now in the cool basement.
I see the wind and solar energy losses involved in recharging those mismatched batteries hasn’t been discussed yet. It’s not good if you’re an energy Hoarder.
The Battery Charger ...
Two Track has a C-60 Charger, which is a fairly good pseudo 3-Stage Charger. If my memory serves me, there should be two dials inside to change/set the Bulk & Float voltages. Unfortunately, I do not think the fixed 1 Cummulative Hour Absorb Charge Time can be changed. So, not quite a true 3-Stage Battery battery but still very good.
The Battery Mismatch ...
Two Track may need to address this issue after we learn what the Charge Parameters are for each type of battery.
One 12 Volt battery in parallel with two 6 batteries in series is not the "best" configuration, for sure.
Proper Charging ...
Yes, I agree proper recharging is very important to long battery life. You are right, too high or too low a temperature is a very important factor, too. The care and feeding of batteries is not an easy task. What is easy -> their early death!
bulk at 14.5
Yes I have diode between battety and panel
Didn't think the 12 volt battety hooked to the two six volt was not good. I have the two 6 Hooked together to make 12 then hooked to 12 in parllel thought it would be same as two 12 I already had that battety before I found out about the 6 volts can't return it wish I could do stuck with it for now.
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