Inverter system

Paul · November 03, 2012, 08:07:57 PM

Looking to install a inverter system in our bus. (MCI 102 A3) Will be using it for electronic, RADIO, TV, VCR, DVD, BLU-RAY and MICOWAVE. (future satelite system)

Some of the equipment that I think we need.
24 volt 2000 watt true sine wave inverter
2 - 12 Volt 8D Glass Mat Battres 255 amp hr. each. (510 amp hr.total) or 4 - 12 volt group 31 125 amp hr. each. (500 amp hr. total.)
4.0 cable, battery to inverter
fuse and holder Kit for 4/0 DC cable (fuse size unknow)
4 or 6 circut Square D, QO load center and breakers.
10/3 WG MC stranded cable to feed inverter from main load center and feed new load center from inverter.
Two pole 30 amp breaker for main load center to feed inverter.

What is the best brand inverter/charger?
Help with switching?
Or any thing that i missed
Your thoughts on battery size.

Any and all help appreciate or input of any kind
Paul

PP · November 03, 2012, 08:42:25 PM

Hey Paul,
Our bus was originally set up with the microwave in the inverter circuit and even though it's a 2kw unit, the microwave proved too much draw. I rewired the microwave to take it out of the circuit and only run the satellite and electronics through the inverter (dear wife must have her TV). By only running the 'necessities' through the inverter, the batteries will last close to a week without a charge and we have a 32" flat screen in the lounge. Our house bank has been reduced to 440 AH so I could put the generator on its own battery bank. Even in a Prevost there is only so much room

HTH, Will

Ralph7 · November 03, 2012, 11:50:52 PM

First I had a 2000W. inverter/charger with a 300amp fuse, it was not a loadshare unit. It poped the fuse!!! That Xantrax was new and never fully charged the house bank!
My house bank is 6, 6V golf cart wired series/paralell, 300amp JLLN fuse,,, New Magnum 2000watt/100ampcharger 12volt and it load shares came with remote, and it works great!!!
Wired direct to pole-then to 120v pannel, 10agw.magnum does pass through auto (Xantrex did not) both units are Pure sine.
My Magnum an remote were less than $1725.00, 24v same $$.
Also have 840watts of solar and 60 amp MPPT, Morningstar controller,,,,, on the hiway the output of the solar over rides the 12volt Alt..
Personally Magnum and Outback are the only good brands!! Outback is pricey! I shopped and bought cheap, it was a $1000.00 mistake, now the new unit is great!
My used Honda 3000si is my only gen.....and it handles the smart 100amp charger. OH i think you need to look at 6Volt batts, longer,deeper cycle, much cheeeeper, but glass matts are good AND you need a good programable inverter, like a Magnum or Outback.
I will tell you who helped me Price wise.

Sam 4106 · November 04, 2012, 02:45:14 AM

Hi Paul,

I can't tell you which inverter is the best but I can tell you that your battery calculations are wrong. When you wire two 12 volt 255 amp hr batteries in series you get 24 volts but you still have 255 amp hrs. If you parallel two 12 volt 255 amp hr batteries you still have 12 volts but you have 510 amp hrs. So, you may need to take that into consideration when sizing your battery bank.

If you plan to ever camp without hookups, you may want to consider other appliances in your calculations. Like hair dryer, curling iron, toaster, coffee maker, refrigerator, furnace, lights, cell phone charger, laptop or Ipad charger, and probably some other things I am not thing about right now. These things all add to the load on the batteries. I used to hate having to start the generator for my wife to use her hair dryer, curling iron and coffee maker. Now with an inverter she can use all of those items. You will notice that there isn't much difference in cost between inverter sizes of the same brand in sine wave units. Size the inverter and battery bank to meet your needs. Either one too small and you will not be happy.

Good luck, Sam

Nick Badame Refrig/ACC · November 04, 2012, 03:31:31 AM

Hi Paul,

You can always use the Power Triangle Calculator used by many electrical engineers.

http://www.sengpielaudio.com/calculator-ohm.htm

Nick-

bevans6 · November 04, 2012, 03:57:40 AM

2000 watts at 24 volts nominal is only 83 amps. Even doubling that for surge currents is 160 amps, so you don't need 4/0 cable. Even 1/0 will do if you are within 10 feet or so of the battery. With that said, nothing wrong with bigger, just not needed - 24 volts vs 12 volts halves the current, and wire is sized for current capacity. Your setup is almost identical to mine, except I used a 3000 watt inverter. I use four 6V 235 AH batteries for a 24 volt, 235 AH bank, and my needs and usage don't even touch it. I use it for over-night stays while on a trip, basically truck-stop boondocking. I am currently shopping for a new inverter, my Samlax decided it didn't like my air conditioner. I am looking at Magnum and Outback, mostly, if there are other recommendations that would be good to explore.

Brian

Paul · November 04, 2012, 10:48:30 AM

Sam
You are right, I was bad on the Battery calculations.

Thanks to all
Paul

Oonrahnjay · November 04, 2012, 10:52:15 AM

Paul, have you thought about the benefits of a manual master cut-off switch?

bevans6 · November 04, 2012, 11:03:33 AM

Quote from: Oonrahnjay on November 04, 2012, 10:52:15 AM
Paul, have you thought about the benefits of a manual master cut-off switch?

Oh yeah - totally forgot about the cutoff switch. I used a three way switch from a marine application to allow me to cut off the house batteries from the inverter, or to tie the start batteries and the bus alternator to the house batteries and the inverter. That is the magic switch that lets me run the inverter from the alternator going down the road. Some people like to use a solenoid for the tie connection, but I just use the three way marine switch.

Brian

bobofthenorth · November 04, 2012, 11:26:06 AM

Couple of comments - background information - we have a Freedom 25 running off 3 x 8D AGM batts.

I don't think 2 x 8D batts is enough. Minimum 3, which is what we have & I don't consider that excess, most of the time we wish we had more.

If I was starting from scratch now there's no way I would wire a separate house and chassis battery system. Right now we carry 5 x 8D batteries. I would wire them as one bank and add a single Group 31 battery to start the generator. That's the way my boat is wired. When we bought the boat I thought it was stupid but I've grown to appreciate how much sense it makes. The bus carries a lot of weight and wastes a lot of space on those 2 x 8D start batteries which get used for maybe 30 seconds every day, usually a lot less. That space/weight could be much better utilized. With even a basic SOC system and a separate genset start battery I don't see any risk of being stranded. Most of the time when you have a fail to start its a dirty or loose connection anyway.

Sam 4106 · November 04, 2012, 11:48:31 AM

Hi Bob,

With your 12 volt house system, it is fine to have three batteries in parallel. Paul is building a 24 volt house bank and would need to use an even number of batteries, however many he chooses to use.

Good luck, Sam

bevans6 · November 04, 2012, 01:17:24 PM

Bob, do you ever use your Freedom 25 to run an air conditioner?

Brian

bobofthenorth · November 04, 2012, 02:06:28 PM

No we don't Brian. We have basement air - I'm not sure what it draws but I don't see any reason why the inverter would not run it because its got 2 compressors on separate 15 amp circuits. Most of the time we only run one side so we're using less than 15 amps. That panel though doesn't run through the inverter so it would require some wiring changes to make it happen. I have run my electric water heater off the inverter though. I've got a three way switch set up so that I can put the water heater on the inverter while we're travelling. I only do that if we're several days away from a power pole but when we do it the inverter handles the load just fine.

And Sam obviously Paul shouldn't have a 24 volt system with 5 batteries. My point was that 2 x 8D batteries is insufficient, no matter whether they're wired for 24 or 12 volts. He could still have a single bank system on 24 volts although I realize that is often more difficult to balance because he likely has both 12 and 24 volt loads. The main point of my post was that people need to at least consider having a single bank with a separate genset battery for redundancy. Carrying multiple batteries around just to start the main engine is pretty silly IMHO, particularly so when people think they only have room for 2 batteries in their house bank.

luvrbus · November 04, 2012, 02:18:15 PM

FWIW I saw a new Prevost conversion that used 8 volt AGM batteries I didn't count the batteries but he had a compartment full he said 6 would give you 551 amp hrs @24volts

good luck

belfert · November 05, 2012, 08:37:27 AM

Quote from: bobofthenorth on November 04, 2012, 02:06:28 PM

And Sam obviously Paul shouldn't have a 24 volt system with 5 batteries. My point was that 2 x 8D batteries is insufficient, no matter whether they're wired for 24 or 12 volts. He could still have a single bank system on 24 volts although I realize that is often more difficult to balance because he likely has both 12 and 24 volt loads. The main point of my post was that people need to at least consider having a single bank with a separate genset battery for redundancy. Carrying multiple batteries around just to start the main engine is pretty silly IMHO, particularly so when people think they only have room for 2 batteries in their house bank.

I assume if I did this I would want to install a proper three-stage regulator, correct? I need to see if my six AGM house batteries would fit into my start battery bay.