chefdennis
Veteran Expediter
my bad, wrong thread...
6 V versus 12 V House batteries
- Thread starter spwohl
- Start date
Life expectancy of a battery is like asking, "How much money will I make in expediting?" The life expectancy depends on the proper sizing of the battery bank, depth of discharge, type of loads, battery maintenance regime, ambient temperature, charging algorithm, and the quality and construction of the battery itself.
One axiom I live by, never skimp on tires or batteries. Another one is, you'll never be disappointed with the best. And a third one, from cooking but also applies to batteries, start with the best ingredients, and then don't [muck] it up.
The last one deals with care and feeding. You need to monitor the battery bank to know when to charge it, when it's charged, how large the amp draws are, everything about it. And you need to fully charge it when recharging. If you discharge too deeply or fail to fully charge it, the best batteries in the world will disappoint you.
The old saying is true - Batteries don't die, their owners kill them.
Battery life expectancy is measured in cycles, where one discharge and (full) recharge is one cycle. The deeper you discharge the battery the fewer cycles you will have. If you can routinely cycle down no further than 80% DoD (Depth of Discharge), meaning you've used just 20% of the capacity, then you will have the full rated life expectancy of the battery.
For most people, using only 20% of a battery bank's capacity between charges isn't practical, unless you have just a snotload of room for a lot of batteries, like an off-the-grid installation. Discharging too deeply dramatically shortens the life of the battery. So, a 50% DoD tends to be the best overall compromise between number of batteries, weight, cost, and time between recharging. That's where sizing the battery bank becomes important, where you figure out how many amp hours you'll draw between recharging, and then double that amount, at least, for the size of the bank, to ensure you do not discharge below 50% DoD.
The relation between the cycle life and the DoD is logarithmic as shown in the graph below. In other words, the number of cycles yielded by a battery goes up exponentially the shallower the DoD. This holds true for all lead acid battery chemistries.
The temperature of the batteries has an effect similar to the DoD chart above, where the lower the temperature, the more cycles the battery will yield, and the higher the temperature, the fewer cycles it will yield. Lower temperatures also mean less available amps, where high temps mean more AH. But heat kills. High battery temperature (90°F, 100°F or more) means more available amps, quicker recharging, but reduced life.
It's best to have temperature compensated charging, where the charger varies the voltage and amperage based on the temperature of the battery. If temperature compensated charging is not done, then it becomes even more important to monitor the battery with a battery monitor.
There are three basic types of lead acid batteries:
Starting batteries, which are designed to deliver quick bursts of high current and therefore has a greater lead plate count. Starting batteries do not handle deep discharges sustains amp draws, as the plates will warp and pit quickly when discharged.
Deep Cycle batteries, deliver less instant energy, but have greater long-term energy delivery. Deep cycle batteries have thicker plates and can survive a greater number of discharge cycles.
Hybrid (or Dual Purpose, or Marine, or Truck) batteries, are a compromise between starting and deep cycle batteries. They are often labeled as "deep cycle", especially for marine applications, but they are merely deeper cycle than starting batteries.
If your amp requirements are minimal (5 amp sustained draw, no microwave ovens) then cheap, Hybrid batteries can be a a good alternative to the better, and more expensive, deep cycle batteries. But in the long run, true deep cycle batteries end up being cheaper per year and per amp hour.
There are three main variations of lead acid batteries, the Wet Cell, AGM (Absorbed Glass Mat) and Gel cell. Wet cells are the traditional batteries where you add water to the batteries. AGM batteries have the electrolyte (the water and acid inside the battery) more or less trapped in a mesh of fiberglass fabric, rather than free-flowing as with Wet Cells. With Gel batteries the electrolyte is suspended in free-flowing a gel-like substance.
AGM and Gel batteries are specialty batteries that typically cost twice as much as a premium Wet Cell. They store very well and do not tend to sulfate or degrade as easily as wet cell. They can take deeper discharges routinely, and will last longer. There is little chance of a hydrogen gas explosion or corrosion when using these batteries. These are the safest lead acid batteries you can use. Both Gel Cell and AGM batteries require a special charging rate which is different from Wet Cell batteries.
Gel batteries are very good for marine applications, but are not well suited for road applications because of its especially critical charging requirements (charge at too high a voltage, even a couple of tenths of a volt too high, and you've killed them dead). AGM batteries are particularly good for road applications because they cannot spill (you can install them upside down) and will not gas while charging. But you've got the make sure you have a proper system in place to charge them, as they require considerably more voltage to charge them than do Wet Cells. Wet Cells are fine for road applications, as long as you do not install them where hydrogen gas can collect, and you are prepared to deal with battery acid sloshing and spilling down the sides of the batteries (good battery caps like Water Miser Caps and either battery boxes or battery mats under the batteries are a must).
AGM batteries will have more cycles than Wet cells, and taller batteries like Golf Cart (BCI GC2), Aerial Lift (BCI 902), Floor Scrubber L-16 (BCI 903) will have more cycles than shorter batteries. 6-volt batteries will have more cycles than 12-volt batteries. 2-volt batteries will have more cycles than 6-volt batteries.
These are some typical (minimum - maximum) typical expectations for batteries if used in deep cycle service. There are so many variables, such as depth of discharge, maintenance, temperature, how often and how deep cycled, etc., that it is almost impossible to give a fixed number.
Trojan T-105 Golf Cart - 500 cycles, 3-7 years
Trojan J-305 Aerial Lift - 650 cycles, 3-7 years
Trojan L-16 Floor Scrubber 700 cycles, 4-8 years
For deep cycle Wet Cells, Trojans are the best. For AGM, Concord Lifelines (and Concord Sun Xtender) are the best. US Battery, Dekka, Discover Energy and Odyssey also made very good batteries. Walmart, Costco, Autozone, not so much. You get what you pay for.
The most common mistakes battery owners make:
Undercharging: Continually operating the battery in a partial state of charge results in the formation of lead sulfate compounds on the plates. This condition is known as sulfation. This reduces the battery's performance and will cause premature battery failure. Undercharging will also cause stratification.
Overcharging: Continuous charging causes accelerated corrosion of the positive plates, excessive water consumption, and in some cases, damaging temperatures within a lead acid battery.
Under watering: In flooded batteries water is lost during the charging process. If the electrolyte level drops below the tops of the plates, irreparable damage may occur. Water levels should be checked and maintained routinely. (Water Miser Battery Vent Caps greatly reduce the amount of water lost during charging.)
Over-watering: Excessive watering of a battery results in additional dilution of the electrolyte, resulting in reduced battery performance. Additionally, watering the battery before charging may result in electrolyte overflow and unnecessary additional maintenance.
One axiom I live by, never skimp on tires or batteries. Another one is, you'll never be disappointed with the best. And a third one, from cooking but also applies to batteries, start with the best ingredients, and then don't [muck] it up.
The last one deals with care and feeding. You need to monitor the battery bank to know when to charge it, when it's charged, how large the amp draws are, everything about it. And you need to fully charge it when recharging. If you discharge too deeply or fail to fully charge it, the best batteries in the world will disappoint you.
The old saying is true - Batteries don't die, their owners kill them.
Battery life expectancy is measured in cycles, where one discharge and (full) recharge is one cycle. The deeper you discharge the battery the fewer cycles you will have. If you can routinely cycle down no further than 80% DoD (Depth of Discharge), meaning you've used just 20% of the capacity, then you will have the full rated life expectancy of the battery.
For most people, using only 20% of a battery bank's capacity between charges isn't practical, unless you have just a snotload of room for a lot of batteries, like an off-the-grid installation. Discharging too deeply dramatically shortens the life of the battery. So, a 50% DoD tends to be the best overall compromise between number of batteries, weight, cost, and time between recharging. That's where sizing the battery bank becomes important, where you figure out how many amp hours you'll draw between recharging, and then double that amount, at least, for the size of the bank, to ensure you do not discharge below 50% DoD.
The relation between the cycle life and the DoD is logarithmic as shown in the graph below. In other words, the number of cycles yielded by a battery goes up exponentially the shallower the DoD. This holds true for all lead acid battery chemistries.
The temperature of the batteries has an effect similar to the DoD chart above, where the lower the temperature, the more cycles the battery will yield, and the higher the temperature, the fewer cycles it will yield. Lower temperatures also mean less available amps, where high temps mean more AH. But heat kills. High battery temperature (90°F, 100°F or more) means more available amps, quicker recharging, but reduced life.
It's best to have temperature compensated charging, where the charger varies the voltage and amperage based on the temperature of the battery. If temperature compensated charging is not done, then it becomes even more important to monitor the battery with a battery monitor.
There are three basic types of lead acid batteries:
Starting batteries, which are designed to deliver quick bursts of high current and therefore has a greater lead plate count. Starting batteries do not handle deep discharges sustains amp draws, as the plates will warp and pit quickly when discharged.
Deep Cycle batteries, deliver less instant energy, but have greater long-term energy delivery. Deep cycle batteries have thicker plates and can survive a greater number of discharge cycles.
Hybrid (or Dual Purpose, or Marine, or Truck) batteries, are a compromise between starting and deep cycle batteries. They are often labeled as "deep cycle", especially for marine applications, but they are merely deeper cycle than starting batteries.
If your amp requirements are minimal (5 amp sustained draw, no microwave ovens) then cheap, Hybrid batteries can be a a good alternative to the better, and more expensive, deep cycle batteries. But in the long run, true deep cycle batteries end up being cheaper per year and per amp hour.
There are three main variations of lead acid batteries, the Wet Cell, AGM (Absorbed Glass Mat) and Gel cell. Wet cells are the traditional batteries where you add water to the batteries. AGM batteries have the electrolyte (the water and acid inside the battery) more or less trapped in a mesh of fiberglass fabric, rather than free-flowing as with Wet Cells. With Gel batteries the electrolyte is suspended in free-flowing a gel-like substance.
AGM and Gel batteries are specialty batteries that typically cost twice as much as a premium Wet Cell. They store very well and do not tend to sulfate or degrade as easily as wet cell. They can take deeper discharges routinely, and will last longer. There is little chance of a hydrogen gas explosion or corrosion when using these batteries. These are the safest lead acid batteries you can use. Both Gel Cell and AGM batteries require a special charging rate which is different from Wet Cell batteries.
Gel batteries are very good for marine applications, but are not well suited for road applications because of its especially critical charging requirements (charge at too high a voltage, even a couple of tenths of a volt too high, and you've killed them dead). AGM batteries are particularly good for road applications because they cannot spill (you can install them upside down) and will not gas while charging. But you've got the make sure you have a proper system in place to charge them, as they require considerably more voltage to charge them than do Wet Cells. Wet Cells are fine for road applications, as long as you do not install them where hydrogen gas can collect, and you are prepared to deal with battery acid sloshing and spilling down the sides of the batteries (good battery caps like Water Miser Caps and either battery boxes or battery mats under the batteries are a must).
AGM batteries will have more cycles than Wet cells, and taller batteries like Golf Cart (BCI GC2), Aerial Lift (BCI 902), Floor Scrubber L-16 (BCI 903) will have more cycles than shorter batteries. 6-volt batteries will have more cycles than 12-volt batteries. 2-volt batteries will have more cycles than 6-volt batteries.
These are some typical (minimum - maximum) typical expectations for batteries if used in deep cycle service. There are so many variables, such as depth of discharge, maintenance, temperature, how often and how deep cycled, etc., that it is almost impossible to give a fixed number.
- Starting: 3-12 months
- Hybrid (Marine): 1-3 years
- Golf cart: 3-7 years
- Gelled deep cycle: 3-6 years
- AGM deep cycle: 4-7 years
- Deep cycle (L-16 type etc): 4-8 years
- Rolls-Surrette premium deep cycle: 7-15 years
- Industrial deep cycle (Crown and Rolls 4KS series): 10-25 years
Trojan T-105 Golf Cart - 500 cycles, 3-7 years
Trojan J-305 Aerial Lift - 650 cycles, 3-7 years
Trojan L-16 Floor Scrubber 700 cycles, 4-8 years
For deep cycle Wet Cells, Trojans are the best. For AGM, Concord Lifelines (and Concord Sun Xtender) are the best. US Battery, Dekka, Discover Energy and Odyssey also made very good batteries. Walmart, Costco, Autozone, not so much. You get what you pay for.
The most common mistakes battery owners make:
Undercharging: Continually operating the battery in a partial state of charge results in the formation of lead sulfate compounds on the plates. This condition is known as sulfation. This reduces the battery's performance and will cause premature battery failure. Undercharging will also cause stratification.
Overcharging: Continuous charging causes accelerated corrosion of the positive plates, excessive water consumption, and in some cases, damaging temperatures within a lead acid battery.
Under watering: In flooded batteries water is lost during the charging process. If the electrolyte level drops below the tops of the plates, irreparable damage may occur. Water levels should be checked and maintained routinely. (Water Miser Battery Vent Caps greatly reduce the amount of water lost during charging.)
Over-watering: Excessive watering of a battery results in additional dilution of the electrolyte, resulting in reduced battery performance. Additionally, watering the battery before charging may result in electrolyte overflow and unnecessary additional maintenance.
