| Author | Message | ||
| Steven Foster (57_gmc)
Registered Member Username: 57_gmc Post Number: 43 Registered: 12-2010 Posted From: 72.156.216.251  Rating: N/A |
I have been reading other threads on electric power. I was looking to put in like a WF8955 which I think will put out 55 amps for the house batteries and can handle the 110 volts from the gen. or shore power... I was wanted to put in a power inverter just for one AC on top and run it off the house batteries. Will 4500 to 5000 watts run a AC unit off the house batteries??? If so about how long will the house batteries will run it before they get weak??? This is without any input to them... Just trying to get from running the gen at night.. Need any ideas on this..... Thanks Steve | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1214 Registered: 8-2006 Posted From: 99.146.10.201 Rating: N/A |
Steve, Here are the electrical formulas you will need to know so you can figure out how many batteries you will need to run a roof air for several hours without a generator. AMPS are the electrical unit of QUANTITY. VOLTS are the electrical unit of PRESSURE. WATTS are the electrical unit of WORK, and are derived by multiplying AMPS times VOLTS. So, 10 Amps at 120 Volts (which it actually is) would require 100 Amps at 12 Volts into an inverter, if the inverter were 100% efficient. In reality, you should figure 85% efficiency, so it will take 110 to 115 Amps of 12 Volt DC to make 10 Amps of 120 Volt AC. EER, (Energy Efficiency Ratio)expressed as BTUs/Watt, tells how much cooling an air conditioner puts out in relation to the amount of power it consumes. So, a 10 EER 13,500 BTU roof air will consume 1,350 Watts. A 12 EER unit will consume 1,125 Watts. 1,350 Watts will require 11.25 Amps of 120 VAC, or about 125 Amps of 12 VDC. A 12 EER rooftop will only draw 9.375 Amps of 120 VAC, or about 100 Amps of 12 VDC. Deep cycle batteries are rated in Ampere-Hours, (how many Amps the battery will put out for how many hours,)and most of us won't discharge our batteries more than 50%, to get some life out of them. So, now all you have to do is figure out how long you want to run your roof air, and buy batteries accordingly. I would strongly advise you to buy a pure sine wave inverter, instead of the much cheaper modified sine wave types. There is a WHOLE lot on this in the archives... HTH, G | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 1491 Registered: 10-2006 Posted From: 69.19.14.40  Rating: |
Will 4500 to 5000 watts run a AC unit off the house batteries??? If so about how long will the house batteries will run it before they get weak??? Maybe 10 min . and perhaps a half hour if you have 1000lbs of batts . Good Luck. FF | ||
| Jim Wilke (Jim Bob) (Pd41044039)
Registered Member Username: Pd41044039 Post Number: 623 Registered: 2-2001 Posted From: 184.0.13.120  Rating: N/A |
It's not practical to run AC while parked from the inverter. But... if you had a 50DN, 300 amp alternator on the main engine, you could run at least two roof A/C units while going down the road, using the battery bank to keep it all going while you are at traffic lights. That would keep you from having to run your generator while driving. We run the genset, which can't be heard while driving, to run the air cond from that. Now that we tossed the propane fridge for an AC one (that actually keeps food cold in the summer), we need 120V for that too. We have an inverter for the occasional coffee pot or 120v lamp, etc while at a rest stop but in practice we don't use it. And you would definitely feel the big alternator on the 6-71. That would be about 7 HP to run that big dog which is not that much on a 300-470 hp bus but a lot on a 6-71. Another reason we run the genset while rolling. | ||
| Teresa (Happycamperbrat)
Registered Member Username: Happycamperbrat Post Number: 113 Registered: 5-2009 Posted From: 72.67.16.123 Rating: N/A |
Would swamp cooling be okay for where you travel? They have some that run on solar for big trucks and some motorhomes have been using them.... Also I hear a lot of good things about the minisplits and scraping by without a generator.... There is also a chest type refer that runs off a 75watt solar panel. | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 1247 Registered: 1-2003 Posted From: 67.142.130.40  Rating: N/A |
Hmm. I guess that depends on your definition of "practical," then. We regularly run an air conditioner from the inverter and batteries while parked, particularly if we need one overnight, when we'd rather not listen to the genny (or waste that much fuel). -Sean http://OurOdyssey.BlogSpot.com | ||
| Mark Renner (Boomer)
Registered Member Username: Boomer Post Number: 234 Registered: 11-2006 Posted From: 75.196.58.192  Rating: N/A |
I have nearly the same house electrical system as Sean's, ie. SW4024 inverter and (8) AGM 8D's. For our purposes, we normally don't ever have to fire up the gen if we are driving daily, or at least every other day, as we have 200 amps coming off the engine to charge the house bats. IIRC, we can run one AC off the inverter for about 8 hrs on low. Going down the road, 2 AC's while the engine is running. I believe Sean pulls off his 50DN engine alternator for house charging, while we have twin 140 amp house charging alts (derated to 100 amp each). This has enabled us to use the coach and rarely have to start the thirsty generator at 1.+ gallons per hour fuel burn unless we are stationary for 2 days or more. | ||
| Jim Wilke (Jim Bob) (Pd41044039)
Registered Member Username: Pd41044039 Post Number: 624 Registered: 2-2001 Posted From: 184.0.13.120 Rating: |
Sean & Mark, Yes, with enough battery and a big alternator & daily driving, it can be done. But how much hp do you guys have? I mentioned that a 4104 doesn't have any extra HP. The original bus AC was run off an aux engine 'cause the 6-71 was only 170hp as originally designed. Even if built to 4 valve specs, it's still 240hp. Steve has a 4104. And the extra weight of 8 8-D batteries is not needed when climbing steep grades with a 4104. I might point out that with the 10 mpg of a 4104, we can afford the 1/2 gal/hour for the genset. We also run two A/C units if we run any at all. One won't keep us cool except at night. And as for the noise of the genset: my bedroom A/C is louder than the genset way in the front bay. Heck, I really do have to look at the indicator light to see if it's running when we're sitting right above it driving down the road. | ||
| jerry garrido (Uemjg)
Registered Member Username: Uemjg Post Number: 38 Registered: 10-2010 Posted From: 70.248.168.139  Rating: N/A |
Sean/Mark, Could you guys provide a block diagram of your electrical system(s) that show your altenator and connections to your batteries, a.c., breaker box, etc.? please email to me if you can...thx. | ||
| Len Silva (Lsilva)
Registered Member Username: Lsilva Post Number: 462 Registered: 12-2000 Posted From: 72.187.35.208  Rating: |
I would also point out that the 4104 is 12 volts, not 24. That 300 amp alternator is only capable of 3600 watts. | ||
| Mel La Plante (Mel_4104)
Registered Member Username: Mel_4104 Post Number: 158 Registered: 7-2006 Posted From: 173.180.124.202 Rating: |
My 4104 has been a MH for 31 years and i have had it 17years , the PO said he ran the AC 3 times but i never have in fact, i am going to take off and put in a fantastic fan in its place. this is one of the joys of living in BC Canada on Vancouver Island--- no bad snakes, swamp critters,thorns,high humidity,flying bugs that bite, and a high summer temp of 95. and how do i live without AC , well my 4104 is on wheels and i head for the shade. | ||
| Jim Wilke (Jim Bob) (Pd41044039)
Registered Member Username: Pd41044039 Post Number: 625 Registered: 2-2001 Posted From: 184.0.13.120 Rating: N/A |
Well, Mel.... Our stompin grounds have been FL, GA, MS winter and summer. Winter is batter. We DO have all you mentioned plus hurricanes. (I prefer mine in a tall glass in New Orleans though.) Day & nite AC is a reality for those tied close to jobs & home. If I were using the big alternator to power the roof A/Cs, I would indeed find a 24 volt unit and dedicate it to charging the house batteries. The rest of the 4104 only needs a car alternator for running lights & fans. That can be belt driven off the front of the engine. | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 1250 Registered: 1-2003 Posted From: 67.142.130.19 Rating: N/A |
That's only relevant when talking about powering, say, an AC while on the road, or trying to load up on charge while driving so that you can run well into the night without running the genny. My statement about running the AC on batteries applies irrespective of how those batteries get charged. IOTW, we do this even when we've been parked for a while, not just while driving or immediately afterward. On days when we need to run a single AC all day long, we'll just let the AC run and leave the genny on auto. The inverter will run the AC 4-6 hours, then start the genny, which will run for 1-2 hours (during which time the other ACs will come on, if needed, just for good measure), then shut it down, and the cycle will repeat. We can run a single AC this way 24/7 with only perhaps four or five hours of genny run time a day, which is a significant savings. All that being said, even if you have no spare horsepower to run a big alternator to charge batteries, you can still get a significant amount of charge for free, with no horsepower required. You just need a setup to pass charge to the house batteries only while decelerating. There are automatic ways of doing this, or you can even put a pedal under your left foot. We practice a version of this on heavy grades. I will turn off the battery intertie when we begin our climb, to save the ~10hp the alternator is costing us. Then when we summit I will turn it back on, and we'll get free power the whole way down, plus we'll save just a tiny bit on the retarder as well.
True, but 3,600 watts is plenty to run a single AC, which would be under 1,800 watts even counting inverter losses. That still leaves you half your alternator to run all the chassis loads as well as charge batteries.
Try this one: http://odyssey.smugmug.com/Architecture/Drawings/63883_XJHit#2228272_zqboe-O-LB or this: http://odyssey.smugmug.com/Architecture/Drawings/63883_XJHit#2294762_RdM4K-O-LB You can also hunt around in that gallery for other drawings. -Sean http://OurOdyssey.BlogSpot.com | ||
| jerry garrido (Uemjg)
Registered Member Username: Uemjg Post Number: 39 Registered: 10-2010 Posted From: 69.155.131.10 Rating: N/A |
thanks sean...I'll be studying those. | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 1479 Registered: 7-2006 Posted From: 97.227.173.128  Rating: N/A |
Sean....U R amazing...thanx !  RCB |
