Harbor Freight 2000 WATT Power Inverter????
Mar 21, 2014 15:16:16 GMT -8
kscountrygal and irish123 like this
Post by cowcharge on Mar 21, 2014 15:16:16 GMT -8
It doesn't matter, 2 6v batteries or 1 12v. Hooking two 6-volters up in series (hook the neg on one battery to the pos on the other) makes one 12v battery (just like stacking C-cells in your flashlight).
My two 230ah 6v golf cart batteries ($220 for the pair at Sam's Club) in series gives me 230ah of 12v (when hooked in series the voltage doubles and the capacity stays the same, in parallel the capacity doubles and the voltage stays the same). I can only use 115 of those amp-hours without recharging because you never want to run your batteries below 50% unless it's an emergency, it shortens their life dramatically. 115ah would allow me to run my furnace (at 2 amps DC) for 57.5 hours, assuming the furnace fan runs constantly (it doesn't, it's more like half the time, so I could actually probably get twice the 57 hours). Same numbers for one 12v light bulb, since they also draw two amps in my camper, 57.5hrs x 2amps = 115 amp-hours. I could run a 1500-watt coffee maker through my inverter for only 55 minutes (1500w/12v=125amps; 115ah/125a=.92h=55m)!
I'm parked off-grid, so I have a big solar panel to keep everything charged, I haven't had to use the generator since I installed the panel back in September (except to run power tools).
To calculate the size of the battery bank YOU need, you must do the math. If you just buy a battery and go camping, you will end up having to modify your lifestyle in order to accommodate the battery's size. For example, on day three you realize you don't have the juice for both lights and the radio, so you have to shut one of them off.
I prefer to start with your electrical needs (lifestyle) and then calculate the size of the battery bank needed to support that lifestyle, rather than shrinking your lifestyle to fit your batteries. Make your lifestyle the constant in the equation, instead of a variable. Make the battery size the variable to be determined. Assuming you have the budget.
The simplest way I know how to explain it is to start with your typical camping trip. Write down everything you will do in the camper that requires electricity, and for how long you will do each activity each day.
Do it like an itinerary, writing everything down. 20 minutes per day with the coffee maker, 6 hours per day with three light bulbs, 2 hours on the laptop, 4 hours of TV, half an hour on the water pump, etc. Then you calculate the electrical needs of each of those, in battery capacity (amp-hours). Once you have each appliance's daily requirements, you total them all up, multiply by the number of days between recharging, and size your battery bank to be twice that total (remember the 50% discharge limit!).
For example, 20 minutes per day using the 110v coffee maker. Look at the data tag on the coffee maker to see what it draws, it'll say either amps or watts. Let's say it's 1000 watts. Watts=Amps x Volts, so divide 1000 watts by 110 volts to get 9 amps AC to run it. Now you have to run it through an inverter to change DC to AC, and it takes nine amps DC from the battery to make one amp AC from the inverter. This means that the 9 amps AC will require 81 amps DC from your battery to run that coffee maker (yow!). Running it 20 minutes per day means it requires 27 amp-hours per day (81 amps x .33 hours/day = 27 amp-hours/day). Multiply that by the number of days you want to camp without recharging, and it will give you the usage requirement for the coffee maker (alone) per trip. Three days of 20 minutes' use will require that your battery bank have 81 amp-hours capacity just for the coffee maker. A Group 24 battery has a capacity of about 80 amp-hours. That means you would need two of them to power your coffee maker for three days at 20 minutes per day without discharging the battery below 50%. That's why few people run appliances with heating elements off batteries.
A 2-amp DC light bulb will burn for 20 hours before it takes that Group 24 battery down to 50% (2a x 20hr = 40amp-hours, or half of the 80ah battery capacity).
So, like the coffee maker, you take every appliance in your camper and calculate how many amp-hours each one needs per day. Add them all up to get your total daily amp-hour requirements to be a happy camper. Sit down if you're prone to fainting, then multiply by the number of days, and double that to get the battery bank capacity you need. Remain seated, and check battery prices. Then check solar prices. Then start figuring out which appliances you can do without, or can use less often.
None of this has taken into account your charging ability. Any charging amp-hours you can stuff into your batteries during the trip can be subtracted from the required total, and subsequently allow you to have a smaller battery bank. So if you run your generator for two hours per day and it puts out 10 amps DC, that's 20 amp-hours being put back into the battery every day, which can then be subtracted from your required daily total capacity.
Hope this has made sense, if there's anything I can clarify just ask!
My two 230ah 6v golf cart batteries ($220 for the pair at Sam's Club) in series gives me 230ah of 12v (when hooked in series the voltage doubles and the capacity stays the same, in parallel the capacity doubles and the voltage stays the same). I can only use 115 of those amp-hours without recharging because you never want to run your batteries below 50% unless it's an emergency, it shortens their life dramatically. 115ah would allow me to run my furnace (at 2 amps DC) for 57.5 hours, assuming the furnace fan runs constantly (it doesn't, it's more like half the time, so I could actually probably get twice the 57 hours). Same numbers for one 12v light bulb, since they also draw two amps in my camper, 57.5hrs x 2amps = 115 amp-hours. I could run a 1500-watt coffee maker through my inverter for only 55 minutes (1500w/12v=125amps; 115ah/125a=.92h=55m)!
I'm parked off-grid, so I have a big solar panel to keep everything charged, I haven't had to use the generator since I installed the panel back in September (except to run power tools).
To calculate the size of the battery bank YOU need, you must do the math. If you just buy a battery and go camping, you will end up having to modify your lifestyle in order to accommodate the battery's size. For example, on day three you realize you don't have the juice for both lights and the radio, so you have to shut one of them off.
I prefer to start with your electrical needs (lifestyle) and then calculate the size of the battery bank needed to support that lifestyle, rather than shrinking your lifestyle to fit your batteries. Make your lifestyle the constant in the equation, instead of a variable. Make the battery size the variable to be determined. Assuming you have the budget.
The simplest way I know how to explain it is to start with your typical camping trip. Write down everything you will do in the camper that requires electricity, and for how long you will do each activity each day.
Do it like an itinerary, writing everything down. 20 minutes per day with the coffee maker, 6 hours per day with three light bulbs, 2 hours on the laptop, 4 hours of TV, half an hour on the water pump, etc. Then you calculate the electrical needs of each of those, in battery capacity (amp-hours). Once you have each appliance's daily requirements, you total them all up, multiply by the number of days between recharging, and size your battery bank to be twice that total (remember the 50% discharge limit!).
For example, 20 minutes per day using the 110v coffee maker. Look at the data tag on the coffee maker to see what it draws, it'll say either amps or watts. Let's say it's 1000 watts. Watts=Amps x Volts, so divide 1000 watts by 110 volts to get 9 amps AC to run it. Now you have to run it through an inverter to change DC to AC, and it takes nine amps DC from the battery to make one amp AC from the inverter. This means that the 9 amps AC will require 81 amps DC from your battery to run that coffee maker (yow!). Running it 20 minutes per day means it requires 27 amp-hours per day (81 amps x .33 hours/day = 27 amp-hours/day). Multiply that by the number of days you want to camp without recharging, and it will give you the usage requirement for the coffee maker (alone) per trip. Three days of 20 minutes' use will require that your battery bank have 81 amp-hours capacity just for the coffee maker. A Group 24 battery has a capacity of about 80 amp-hours. That means you would need two of them to power your coffee maker for three days at 20 minutes per day without discharging the battery below 50%. That's why few people run appliances with heating elements off batteries.
A 2-amp DC light bulb will burn for 20 hours before it takes that Group 24 battery down to 50% (2a x 20hr = 40amp-hours, or half of the 80ah battery capacity).
So, like the coffee maker, you take every appliance in your camper and calculate how many amp-hours each one needs per day. Add them all up to get your total daily amp-hour requirements to be a happy camper. Sit down if you're prone to fainting, then multiply by the number of days, and double that to get the battery bank capacity you need. Remain seated, and check battery prices. Then check solar prices. Then start figuring out which appliances you can do without, or can use less often.
None of this has taken into account your charging ability. Any charging amp-hours you can stuff into your batteries during the trip can be subtracted from the required total, and subsequently allow you to have a smaller battery bank. So if you run your generator for two hours per day and it puts out 10 amps DC, that's 20 amp-hours being put back into the battery every day, which can then be subtracted from your required daily total capacity.
Hope this has made sense, if there's anything I can clarify just ask!