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Old 01-21-2013, 08:56 PM   #41
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Originally Posted by Cuttinchief View Post
Thanks could you email me a link to a video or send me a wiring diagram? I have heard if you had a 6 battery bank you could run an A/C but I would like to operate all my outlets and save gas. I have the best generator a Honda 6500iu and my 5 er is all 120v and my Honda has a switch that will allow me to run everything on my RV at the same time to include both A/C units. I just want something that will allow me to operate my trailer without a generator except to charge my batteries. I just can't find a good enough how to guide to do it without burning my camper down HAHA.
Not sure what you are asking.
My wiring diagram is right below my post...

When you find a "how to guide" that will allow you to do that; and it weighs less than several thousand pounds; let me know too. I want one...

Lets say you want to run 2 15K AC units at the same time in your 50 amp coach. (I have actual data on my 15K air conditioner so I won't have to guess).

First, you will need 2 inverters; one to handle each leg of your 50 amp service. The battery bank, however, will "see" the load on both inverters at the same time.

Start-up current on the ACs (since they are inductive motors) run about 26-28 amps per unit and "mellow out" at about 15 amps per unit when up to speed.

If they both kicked on at the same time your peak load will be 28 amps x2 or 56 amps at 120 volts (nominal) or 6720 watts of power for about 15 seconds from your battery bank. (Your inverters must be rated at 3000 watts running with 3500 watts peak EACH to accomplish this feat.)

To create 6720 watts using 12 volts battery power, your bank will need to momentarily supply 6720/12 = 560 amps for about 15 seconds. Spread over 6 12 volt batteries 560/6 = 93 amps PER battery.

Suppose you have six FULLY CHARGED 160AH Trojans as your bank. That would be a 50% of capacity draw for about 15 seconds. Using the example chart below that plots the battery capacity reduction as a function of percent of total capacity (since it will plot out to the extreme far right of the curve), we will say your battery capacity would decline to 30%; and recover after 15 seconds to the run state of 15 amps (per AC) at 120 volts or 3600 watts.

To create the 3600 watts (running) at 12 volts would require what is left after starting the fan and compressor to supply the 50 runtime DC amps PER BATTERY to keep both ACs running.

30% of 165 AH = 50AH per battery as the capacity remaining after both ACs started. A 50AH draw on a 50AH (remaining) capacity battery will run dead in about 45 minutes or less depending on if there is something else going on (like running lights or the radio.

Trust me, your 6500 watt generator is doing all it can to run 2 air conditioners. Trying to replace your generator with a battery bank will require several banks of 6 heavy duty Trojans to get the "per battery" draw down to 25 AH each at the peak start up current demand.

6720 watts required at 12 volts 560 amps - divided by 25 amps nominal per battery = twenty three (or more) 165 AH batteries to give you all day (8 hours or so) relief.

Charging them would also be a problem. To REPLACE the amps you sucked out of 23 or 24 165AH batteries could take weeks with a dedicated battery charger.

Obviously if you could time the start of each AC so they don't try to start at the same time; it would not be so bad...
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Old 01-21-2013, 08:59 PM   #42
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Originally Posted by Stanleyg View Post
Here is a quick drawing on how to wire your batteries direct to your inverter to get the most out of your batteries.
Don't forget to size your wires appropriately for the size inverter you have and fuse the wires to the maximum draw expected at peak wattage output.

Wire Capacity Chart
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Old 01-21-2013, 09:00 PM   #43
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We've got an extra 800KVW tractor-drawn generators that we just demobilized from Sandy..... Maybe that would help recharge those 24 batteries, Herk! The generator only burns about 6 gallons of diesel fuel per hour at 60% load......
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Old 01-21-2013, 09:44 PM   #44
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Originally Posted by Stanleyg
Here is a quick drawing on how to wire your batteries direct to your inverter to get the most out of your batteries.
Thanks Stan this is what I'm looking for. To charge batteries you would just hook up the same way as you would with the inverter but place the charger clips on the first hot and last hooked up neg. Correct? Thanks
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Old 01-21-2013, 09:52 PM   #45
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Originally Posted by Cuttinchief View Post
Thanks Stan this is what I'm looking for. To charge batteries you would just hook up the same way as you would with the inverter but place the charger clips on the first hot and last hooked up neg. Correct? Thanks
Correct.
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Old 01-21-2013, 10:08 PM   #46
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Originally Posted by Cuttinchief

Thanks Stan this is what I'm looking for. To charge batteries you would just hook up the same way as you would with the inverter but place the charger clips on the first hot and last hooked up neg. Correct? Thanks
If someone would purchase a 3000w or 5000w and stepped your trailer plug down to a 30 amp 110 plug which is made. You could operate the entire trailer for the most part off of the batteries couldnt you. Or because most inverters have multiple plugs is the power distributed to all the plugs equally or can the single plug draw all the amHrs by it self? Herk said he bought one that was two big so I don't quite understand that ?
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Old 01-21-2013, 10:14 PM   #47
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Originally Posted by herk7769

Don't forget to size your wires appropriately for the size inverter you have and fuse the wires to the maximum draw expected at peak wattage output.

Wire Capacity Chart
Herk,

You said you thought you purchased two big of an inverter but I was thinking of building a 4 battery bank and setting a 3000 to 5000w pure sine and step down my 50 amp trailer to a 30 amp 110 plug and plug it into one of the plugs in the inverter except I don't know if the inverter splits the power usage out among the outlets or they all tie together nod all the power can come off of one plug. Most 3000w will have a 30 amp fuse so sounds like a max ampHR it can handle per unit. What do you think?
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Old 01-21-2013, 10:19 PM   #48
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In order to run your whole trailer for an extended period of time, you would need a huge bank of batteries and a way to charge them. Depending on what you want to run and for how long would determine how many batteries you would need.

If you would like some really good deep cycle batteries, go to your local cable company maintenance office and ask if they have backup power supplies and how often they change the batteries. I work for one here in Nova Scotia and we change ours on a regular basis. The only reason for changing the batteries out is that they are more than 5 years old, but they are still fully charged and all other readings we take on them is fine. we sell them for under $25 each, so you can get a big bank for about the same as you would pay for 1 or 2 new batteries that may not be as good as these are.
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Old 01-21-2013, 10:27 PM   #49
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Herk,

You said you thought you purchased two big of an inverter but I was thinking of building a 4 battery bank and setting a 3000 to 5000w pure sine and step down my 50 amp trailer to a 30 amp 110 plug and plug it into one of the plugs in the inverter except I don't know if the inverter splits the power usage out among the outlets or they all tie together nod all the power can come off of one plug. Most 3000w will have a 30 amp fuse so sounds like a max ampHR it can handle per unit. What do you think?
John,

Did you read my post? I think I was pretty clear (or at least the best I can do) to explain why this will not work. You would need 24 batteries; not 4.

And two inverters; not one. Your 50 amp trailer has two 50 amp 120 volt legs in that plug. One of your air conditioners is on the second leg. If you use a 50 -> 30 amp adapter you will only get your primary circuits and not the secondary circuits (where your back air conditioner lives).

A 3000 watt inverter has no "fuses" 30 amp or otherwise. It has a low battery cut out circuit that shuts the inverter down to prevent destroying your battery bank and a high wattage monitor circuit to shut the inverter down if you try to pull more watts than the inverter is designed to handle. The inline fuse is to prevent a BATTERY fire in the event you have a short circuit in the inverter.


3000 watt output is 120 volts times 25 amps. To MAKE 3000 watts of 120 volt power; you need to suck the equivalent amperage and voltage from the battery bank. This is disregarding a 1.0 to 1.5% loss inside the inverter due to inefficiency.

So simply put 3000 watts out requires 3000 watts in. To make 3000 watts on the DC side requires 3000 divided by 12 volts or 250 AMPS.

250 amps at 25 amps per battery is TEN 100AH batteries for a useful battery life.
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Old 01-21-2013, 10:58 PM   #50
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John,

Did you read my post? I think I was pretty clear (or at least the best I can do) to explain why this will not work. You would need 24 batteries; not 4.

And two inverters; not one. Your 50 amp trailer has two 50 amp 120 volt legs in that plug. One of your air conditioners is on the second leg. If you use a 50 -> 30 amp adapter you will only get your primary circuits and not the secondary circuits (where your back air conditioner lives).

A 3000 watt inverter has no "fuses" 30 amp or otherwise. It has a low battery cut out circuit that shuts the inverter down to prevent destroying your battery bank and a high wattage monitor circuit to shut the inverter down if you try to pull more watts than the inverter is designed to handle. The inline fuse is to prevent a BATTERY fire in the event you have a short circuit in the inverter.

3000 watt output is 120 volts times 25 amps. To MAKE 3000 watts of 120 volt power; you need to suck the equivalent amperage and voltage from the battery bank. This is disregarding a 1.0 to 1.5% loss inside the inverter due to inefficiency.

So simply put 3000 watts out requires 3000 watts in. To make 3000 watts on the DC side requires 3000 divided by 12 volts or 250 AMPS.

250 amps at 25 amps per battery is TEN 100AH batteries for a useful battery life.
So running an AC may not be readable without some huge dolor powered home system. I guess a 4 battery in parallel with a 2000w inverter should run a fan and TV and a few lights for the night .then charge them up the next day and just run my 6500ui Honda to power all my needs during the day. My Honda is neat because it can operate as a split leg as you indicate or will actually handle both legs if the switch is in the 120v setting kind of a special generator but of course I paid for it also. You know the saying you get what you pay for and it's super, super quiet.
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