Battery life calculations
Optimum temperature for battery operation 25C
|Well ventilated room||33C||50%|
|Desert, elevator room, under sun, etc.||42C||10%|
Types of battery vs lifetime
If battery used for UPS (deep discharge cycles)
|Type of battery||Expected Lifetime(years)|
|AGM deep cycle||4-8|
|Industrial deep cycle||10-20+|
|Gelled deep cycle||2-5|
Discharge depth vs lifetime
For example cheap Deep Discharge 120 Ah battery cost in Lebanon now $100. With 100% usage battery can output 1.44 KwH.
- There is 2 times per day cutoff in my area, up to 3 hours each. This means for 3 year lifespan i need 2190 cycles at least. This means i should keep DoD near 30%.
Smallest house consumption, acceptable, is 5A 220V, means 1.1Kwh/hour. To handle 3 hours i need 3.3 Kwh, with DoD 30% = 11 KwH battery capacity. Total is 8 batteries, $800 per 3 year.
- If i keep DoD for 1 year only, 50%, then i need 6.6Kwh, 5 batteries, and i need for 3 year to change 15 batteries. Almost twice, $1500.
- If i keep DoD 10% only, i need 33kwh, 23 batteries, $2300, which will last 7 years, which is ~$985 for 3 year.
So the most efficient are to keep 50% DoD.
|Charge %||Charging rate %/hour|
So if you have DoD 50%, you need 1.5 hour to reach 70%, and 7.5 hours to reach 100%. This means time between cutoffs should be not less than 9 hours, otherwise you will have less capacity at next cutoff. As a solution, you can calculate system with lower DoD, e.g. for 40% DoD you need 8.5 hours, and 30% DoD you need 7.5 hours.
- NOTE! During charge, system will draw amps from your supply. E.g. 8 batteries to charge 100% in 1 hour (theory only, it can't be done) we need to supply constant 960A on 12V or 52.37A on 220V. But because we charge 14% per hour we need 7.28Amps on 220V per hour for 1.5 hour, and 2.08A for 7.5 hours.
For our "best" DoD 30%, we need only 4%/hour, 7.5 hours chatging with 2.08A taken from 220V. With 70% charger efficiency expect 3A.
- NOTE for solar power! If sunny days only 5 hours, this means we can have DoD only 20%. 6 hours - 24%.
House avg consumption 400 kWH / 3 month 5 kWH per day 2010 Feb $140 - 100Ah lead acid battery $800 - diesel generator 20Amps, 1.3 litre per hour 600$ charger (80Amps?) inverter 150$ (two, each 10A)
1)Deep cycle battery
http://www.cclcomponents.com/product.asp?ID=1390 Victron Phoenix MultiPlus 48V 3000VA Inverter, 35A Charger, 16A Transfer, 230VAC, Parallelable Our Price: £1,615.00
2.30V to 2.35V/cell
- Advantage: Max Service Life/Cool under charge/Ambient charge temperature may exceed 30°C.
- Disadvantage: Slow charge time/Capacity readings tend to be inconsistent and decline with each cycle/Sulfation may occur when no topping charge applied.
2.40V to 2.45V/cell
- Advantage: Fast charge time/Consistent readings/More sulfation resistant.
- Disadvantage: Charging at high room temperatures not recommended/Hot batteries may fail to reach voltage limits/This causes extreme overcharging/Subject to corrosion.
Best way to monitor charge status, is open drain, prefferably after 6 hours idle. Not real for telecom apps in Lebanon, sadly. So left is only monitoring voltage under load, not precise, but there is hope i can build useful way to monitor level of discharge by monitoring various parameters (voltage drop curve, environmental temperature).
UPS and EDL
- Typical lebanese household pay usually also 5A for "ishtirak", now around $100/month. This means total is $1200/year, and $3600 per 3 years.
- With UPS option, expenses:
- Charger + inverter $600 (TODO)
- Batteries $800 (8*$100, 120Ah), they can "output" (2 cutoffs, each 30% of capacity, 6.8 Kwh per day, 204 kwh per month)
- EDL monthly payment increased $0.42 per kWh? up to $85/month.
So we have to compare with "ishtirak" to pay $85 for additional EDL consumption, and $15 saved. 15*12*3 = $540 saved.
- Conclusion: Doesn't worth it...
UPS + own diesel
Fuel price now 30000LL/20L, 1500LL/liter. Isuzu 20kWa - $7499, 80 amps ROI 2 years - $312 month 180 hours per month, 2000 hr warranty, 11 month. 7 liter per hour, with 6 hr per day runtime - $1260/month 16 households for 5 amps, $78 each. $12/month for ROI, $4608 for 2 years. Not profitable.
Liquid propane vs Diesel
- Typical propane consumption is roughly 0.25 gallons of propane per hour, for every 1,000 watts the generator is producing (i.e., 1 gallon per hour when the generator is supplying a load of 4 KW).
- Typical gasoline consumption is roughly 0.2 gallons per hour, for every 1,000 watts of power produced.
- Typical diesel consumption is roughly 0.1 gallons per hour, for every 1,000 watts of power produced.
US retail prices (2012 Apr)
- $1.26 per gallon (LP)
- $3.3 per gallon (diesel)
1Kw price per hour
- $0.3150 for LP
- $0.33 for diesel
There is some other technical notes, as:
- -Diesel generator converted to propane can output 20% less power (less efficiency), it will affect generator ROI terms.
- -Efficiency at partial load with propane will be worse
- +More eco-friendly
Electricity generating ships
For now raw calculations, just curious, how it is efficient to compare with regular diesel generators. Sure many things are not counted, EDL has much higher losess IMO, due inefficent transmission lines, old counters (reactive/active energy) and etc. This calculations can be incorrect, mail me if you see any mistake.
“KARADENIZ would secure a ship that produces 180 MW and would be connected to the Zouk power plant during a period of four months at a cost of $0.0653 per kwh to transfer the power. To this the consumption of an average of 214 g/kwh needs to be added with the agreement that the government consume a minimum of 8,100 electricity hours per year. Therefore, solely renting out the equipment, without including the cost of the heavy fuel oil, over a period of five years would cost $429 million.”
Read more: http://www.dailystar.com.lb/News/Politics/2012/Mar-25/167926-mikatis-counterproposal-calls-for-construction-of-power-plants.ashx#ixzz1tOGup19k (The Daily Star :: Lebanon News :: http://www.dailystar.com.lb) Expenses:
- Rent price: 429000000/5/365/24 = $9794/hour for 180MW, $0.05441 per kw . BUT if wessel are operating 100% of time. If not, cost per kwh is higher.
- Heavy fuel oil, IFO180, $753/tonn, $0.753 per kg
- Diesel MDO, $1022/tonn, $1.022 per kg
- Transportation $0.0653 per kwh
- 214g of IFO180 (1kwh) will cost $0.161142 fuel + $0.0653 transportation + $0.05441 leasing = $0.280852 per kwh
- For regular diesel, 0.378 liter per kwh, 850 grams/liter density, 0.32kg per kwh, $0.32704 per kwh, without maintenance cost
Important part. If wessel will operate only 50% of time, this means it will produce twice less kwh, leasing cost will be double. 0.280852+0.05441=$0.335262 . More expensive than "ishtirak"! But 8100 hours per year, means at least 92% utilisation. Not clear, if it is max or minimum, since if rent price is fixed, owner of ship interested in less usage, to minimize equipment maintenance expenses and wear level. If in opposite, why? Some other indirect expenses? E.g. price of fuel is not market, and he add some % to it?