Amp hours and charging October 31, 2010, 04:11:08 pm Yahoo Message Number: 117896I have several questions about "house" battery capacities, drain, and recharging.1-What would be an average amp hour drain for an overnight stay, say 12-15 hours, with a 27' Lazy Days. This assuming that you would not be plugged into power, and the reefer would be running on propane. Also assuming having several interior lights on, water pump, toilet pump, and misc.2-How long does it take to put back, say 100 amps, into the house bank. a) By running/driving off RV engine. b)By running the generator.Just curious. Trying to compare to my boat.Ernie Hutchins
Re: Amp hours and charging Reply #1 – October 31, 2010, 04:40:22 pm Yahoo Message Number: 117899Water pump is minimal, and RVs don't use a separate toilet pump or macerator. Assuming no TV, DVD, satellite, computer or other appliances you did NOT mention, lights usually draw 1-2 Amps while on, each. If on for 8 hrs, 2 lamps, that would be 24 to 60 A-hrs. Since the stock LD battery bank is about 225 A-hrs, this means a maximum discharge to about 80% of 112 A-hrs, or about 90 A-hrs - not recommended to go lower. Complete recharge times with the stock converter with generator will be long, since the charge rate is low - faster with an alternator, but will still take several hours. As it nears full charge, the battery will accept much less current, so patience is needed. Now most LD owners have various accessories and modifications that make the above pretty meaningless. Extra batteries, solar panels, improved converters or inverter/charger systems, and higher-efficiency lights and appliances will, and do, improve things dramatically.Steve
Re: Amp hours and charging Reply #2 – October 31, 2010, 05:22:37 pm Yahoo Message Number: 117901On Sun, 31 Oct 2010 20:11:06 -0000, "erniehutchins42" wrote:Quote1-What would be an average amp hour drain for an overnight stay, say 12-15 hours, with a 27' Lazy Days. This assuming that you would not be plugged into power, and the reefer would be running on propane. Also assuming having several interior lights on, water pump, toilet pump, and misc. We never have several lights on. Sometimes two at a time. We are normally asleep by 9:30. We seldom watch TV as we seldom have a signal. The furnace fan is a big amp consumer, so we try to adjust our elevation or latitude so we don't need the furnace. So within those parameters, we will use 20 to 40 amps a night. 40 is when we don't get meaningful sun until after 9am.Quote2-How long does it take to put back, say 100 amps, into the house bank. a) By running/driving off RV engine. b)By running the generator. Either way hours longer than I would want to think about. Continuous deep discharge of lead acid batteries will shorten their lives and 100 is about 50% - way too low. Suggest you get a battery monitor so you can tell what each item uses and to tell your discharge percent.Cheers, Don
Re: Amp hours and charging Reply #3 – October 31, 2010, 05:28:36 pm Yahoo Message Number: 117902"What would be an average amp hour drain for an overnight stay, say 12-15 hours?" The water pump's power usage is insignificant in this context, because it runs for such short periods. The main power consumers in your scenario will be lights and fans... plus of course any TV or radio usage. But since you didn't mention the latter two, I'll ignore them.The fluorescent lights draw 2.5 amps apiece. Standard incandescent interior lights, such as those found in the bathroom, draw 1.5 amps apiece.Halogen reading lights typically draw 1 amp apiece. A Fan-Tastic fan draws 1 amp on its low speed setting, and a bit over 2 amps on high. The furnace draws about 3A when running, but of course it only runs intermittently, so its amp-hour consumption will be less. How much less depends on how cold it is outside. The dashboard stereo (which is powered by the house batteries) typically draws 1 amp or less. You can figure out how long you're likely to be using these various devices and do your own calculations. Add about 1 amp for "background" devices such as the propane detector and refrigerator controller board. Your house batteries give you about 110 amp-hours of usable capacity, so whatever number you come up with, compare it to that.Andy Baird http://www.andybaird.com/travels/
Re: Amp hours and charging Reply #4 – October 31, 2010, 05:36:24 pm Yahoo Message Number: 117903Quote Water pump is minimal, and RVs don't use a separate toilet pump or macerator. Assuming no TV, DVD, satellite, computer or other appliances you did NOT mention, lights usually draw 1-2 Amps while on, each. If on for 8 hrs, 2 lamps, that would be 24 to 60 A-hrs. Since the stock LD battery bank is about 225 A-hrs, this means a maximum discharge to about 80% of 112 A-hrs, or about 90 A-hrs - not recommended to go lower. Complete recharge times with the stock converter with generator will be long, since the charge rate is low - faster with an alternator, but will still take several hours. As it nears full charge, the battery will accept much less current, so patience is needed. Now most LD owners have various accessories and modifications that make the above pretty meaningless. Extra batteries, solar panels, improved converters or inverter/charger systems, and higher-efficiency lights and appliances will, and do, improve things dramatically.Steve Thanks Steve-----sort of a sanity check comparing RV's to a boat. Pretty much what I expected. Not much of a difference. We run 100% LED lighting so most 1/2 amp hour. Most under 50' trawlers dont use TV, DVD, or dishes, unless they have a Genset. (we dont) Most have to run reefers off the house bank though. 70-100 amps in a 24 hour period, depending on time of year. I run six, 6 volt golf cart, deep cycle batteries, for house bank. 720 total amps, so never come close to 50%. Like you mentioned takes a long time to put back 90% after down a couple of hundred amps. We have a "smart charging" system that directs a majority of flow from engine alternator to the most needed battery bank. So cuts charging time on a couple of hundred amps from 6-7 hours of cruising to about 2-3 hours. Not to many places to plug in when your in the back and beyond.
Re: Amp hours and charging Reply #5 – October 31, 2010, 05:37:21 pm Yahoo Message Number: 117904"Suggest you get a battery monitor so you can tell what each item uses and to tell your discharge percent." I strongly second Don's recommendation. If you're doing a significant amount of boondocking, and you need to watch your power consumption, a computerized battery monitor such as a LinkPro is absolutely essential. All the numbers I gave in my last post were read directly from my XBM battery monitor. You can't get amperage, much less amp-hour information, from a voltmeter, no matter how accurate it is. Only a battery monitor can do this, because its computer keeps a running total of every milliamp that goes into or comes out of your battery bank. There's no substitute for this information when you're "off the grid." Andy Baird http://www.andybaird.com/travels/
Halogen and LED lamps Reply #6 – October 31, 2010, 05:41:53 pm Yahoo Message Number: 117905There have been many threads about swapping LED for Halogen lamps. I never went forward with this as I did not know the name of the base or what the LED light would look like. Last month I had a chance to put an LED in my rig and compare it to the light from the halogen. The lumens were about the same. It was warm white, pleasing to many, but I prefer a cooler light. Fortunately, the LED supplier offers it in a cool white.Here's the really good part. The halogen uses .8amps, while the LED uses about .1amps. That's significant!Cheers, Don
Re: Amp hours and charging Reply #7 – October 31, 2010, 05:46:49 pm Yahoo Message Number: 117906Quote "Suggest you get a battery monitor so you can tell what each item uses and to tell your discharge percent." I strongly second Don's recommendation. If you're doing a significant amount of boondocking, and you need to watch your power consumption, a computerized battery monitor such as a LinkPro is absolutely essential. All the numbers I gave in my last post were read directly from my XBM battery monitor. You can't get amperage, much less amp-hour information, from a voltmeter, no matter how accurate it is. Only a battery monitor can do this, because its computer keeps a running total of every milliamp that goes into or comes out of your battery bank. There's no substitute for this information when you're "off the grid." Andy Baird http://www.andybaird.com/travels/ Andy---Thats good! (sorry I did not mention in my first post that I am amp hour anal!) My Xantrex Link 2000 monitor, on the boat, shows the same charge rate at 98-99% of capacity. Its been years(35) since I have had any experience with a motorhome. We sure seem to be talking apples to apples comparing boats to RVs.Ernie Hutchins
Re: Amp hours and charging Reply #8 – October 31, 2010, 06:55:50 pm Yahoo Message Number: 117909TV, DVD, or dishes, unless they have a Genset. (we dont) Most have to run reefers off the house bank though. 70-100 amps in a 24 hour period, depending on time of year. I run six, 6 volt golf cart, deep cycle batteries, for house bank. 720 total amps, so never come close to 50%. The RV battery banks are smaller - weight limitations. However, fridges are always propane when dry-camped, so minimal power consumption. On land, of course, solar is not just affected by the weather, but also obstructions. In winter, recharge ability may be half that in summer, with good exposure and full sun.Steve
Re: Amp hours and charging Reply #9 – November 01, 2010, 11:51:57 am Yahoo Message Number: 117916I am going to slightly change this thread.Our last trip was spent mostly in the PNW, under gorgeous trees and cloudy skies. We had 40 hours on the genset when we left after 2.5 years of use. We were up to 110 hours when we got back after five months. I have been thinking of adding batteries and now we have the storage to do it. But, after a little more thought, I am wondering if it will really help us. If we hung out in the SW, given our amp usage, we would seldom have a need for more than two batteries. The light there is bright, tree free and usually reliable. It's all those other states that give us problems. We can handle one or two no recharge days, without much hardship. We can recover from two 20amp use days and no recharge. It's a series of no charge days that makes us turn on the genset. A 100 watt panel can produce 8.3 amps max, [100/12 - forget boosting] We have three panels so our max would be 25amps. I have seen 21 on the display for brief periods, more commonly we see 12 to 14 during prime time and to 5-8 in the mornings and afternoons if it's bright day.8 amps for five hours is 40 amps, which is our max overnight usage. Under these conditions we have no problem getting back 100% every day, usually by noon in the SW. I understand having one panel per battery is rule of thumb. Right now, we have three panels to two batteries and room to add a panel. If we increased to four batteries, we would have 80 amps to use, (400 * 20%) This would be most desirous when parked under trees or it rains, etc. However, we would still have only 40 or so amps available for recharging, so it might take two or more days to return to full charge. I am wondering if spending $1,500 is the right approach. I could swap the T105's for T145's and pick up 15 useable amps, when the time comes to replace the current batteries, [260amps - 225amps = 35amps times 2 batteries times 20%) The T145's are 3/4 inches higher, but could be fitted in the compartment with a few changes, including removing the battery tray.I am trying to fairly evaluate these options: 1) Do nothing, it's not a problem most of the time. 2) Got to four AGM batteries and another panel. 3) Use T145's when the T105's need replacing. 4) Hang out the SW.Any thoughts?Cheers, Don
Re: Amp hours and charging Reply #10 – November 01, 2010, 12:15:40 pm Yahoo Message Number: 117917Don, If you're making ends meet most of the time electrically speaking, then I'd do nothing until and unless you are boxed in one way or another and have identified what your real shortcomings and needs will be.Yonder has: 400 watts of solar that nets 25 amps (boosted) to the batteries regularly. 450 amp hours of battery bank. Prosine 2000 with programmable 100 amp 3 stage charger, so running the gen-set when necessary (not often) is an efficient way to charge batteries. Note that 100 amps is understating things, as initial rate is over 110 amps. We use TV, satellite receiver, computer, and morning electric coffee pot, so overnight consumption is 60 to 90 AH. Solar usually replenishes this by late morning. We most often have a surplus of power and capacity available. I've even run an extension cord to charge a friend's RV's batteries! I think Andy's oft stated solar to battery ratio is 1 watt solar capacity to 1 AH battery capacity.bumper
Re: Amp hours and charging Reply #11 – November 01, 2010, 12:44:24 pm Yahoo Message Number: 117918QuoteA 100 watt panel can produce 8.3 amps max, [100/12 - forget boosting] We have three panels so our max would be 25amps. I have seen 21 on the display for brief periods, more commonly we see 12 to 14 during prime time and to 5-8 in the mornings and afternoons if it's bright day. Don, actually your 100/12 DOES give current output WITH MPPT boosting. Since the maximum power voltage output of your panels is probably about 17V, this means without MPPT, maximum current would be about 100/17 = But, as the batteries charge up, they will accept less charge current, typically but 13.2V it will be 1A or less per battery, so the recharge time stretches out. However, with MPPT, you will have more current available to use for other needs, while still recharging the battery bank. Another thing to note is that your panels are rated at one 'sun' at 'room' temperature. In the real world in our northern hemisphere, expect at best 20 - 30% less maximum performance.Steve
Re: Amp hours and charging Reply #12 – November 01, 2010, 01:31:44 pm Yahoo Message Number: 117920My choice would be Do Nothing. If that doesn't work out, I would replace the current 2 batteries with 4 when they need it. Most people have trouble running their generator often enough anyway. Inventing an 80/20 rule here, I figure that if my system works for 80% of what I do, I'll stick with it. It can get expensive fast to chase a system that is exactly what you want 100% of the time.Rich '03 MB
Re: Amp hours and charging Reply #13 – November 01, 2010, 02:22:45 pm Yahoo Message Number: 117922This doesn't have to be complicated. It all comes down to two questions.1. In the locations where you usually dry-camp, do your solar panels charge your batteries to 100% every day, or nearly every day? If not, you need more panels.2. Assuming your batteries are at 100% by sunset, do they store enough power to last you through the night? If not, you need more batteries.It's really that simple.Andy Baird http://www.andybaird.com/travels/
Re: Halogen and LED lamps Reply #14 – November 01, 2010, 04:52:22 pm Yahoo Message Number: 117923Hi Don, At th risk of starting another LED thread, which lamp did you buy and into which fixture did you try it? BTW, we met at the mothership this year. Thanks for telling us about the Ladeze meeting that weekend. We did meet up with them the last day and enjoyed the company. Don't forget to wax Koko. She worked hard this trip. Nothing like a day at the spa!! Regards, Lydia and Robin 30 IB 2006 AE
Re: Amp hours and charging Reply #15 – November 01, 2010, 06:24:33 pm Yahoo Message Number: 117925The other side of the energy coin is using less rather then getting more. Much less expensive over the long haul.Here are a few little things we do to conserve our batteries.1) When I bought a new laptop recently, I got the extended life battery. Good for about six hours of use. I charge it up in the morning when the solar panels are at work then the PC battery lasts the rest of the day & night. The way I see it, if I you use the computer for more then an hour or so each day, I should just stay home anyway. 2) I don't need a light if I'm using the laptop at night. I have a small LED lamp that plugs into a USB port. Gets its power from the computer, not the house batteries. 3) My wife likes the bathroom light left on all night as a night light. Lost that debate years ago. Mike Coachman steered my to a nice LED light that is a direct replacement for the bulb. Costs $20 but that's much cheaper then replacing the wife. :-)Would be interested in hearing other energy savings ideas.EdSquinting in the dark.
Re: Amp hours and charging - T-145 Batteries Reply #16 – November 01, 2010, 08:00:50 pm Yahoo Message Number: 117926Hi Don,I went to T-145s
Re: Amp hours and charging Reply #17 – November 01, 2010, 08:12:08 pm Yahoo Message Number: 117927"My wife likes the bathroom light left on all night as a night light." So do I, which is why I mounted a Hampton Bay solar "fencepost light" under the shower skylight. Its solar panel charges all day, and its two amber LEDs shine all night, giving just the right amount of light. You can find these at Home Depot and other hardware stores for ten bucks each--a bargain. I mounted another one outside by the door, so I never have to remember to turn the entry light on or off. And there's no house-battery drain. :-)Andy Baird http://www.andybaird.com/travels/
Re: Amp hours and charging Reply #18 – November 01, 2010, 08:55:48 pm Yahoo Message Number: 117928I tried that a few years back. The majority of my camping is
Re: Amp hours and charging Reply #19 – November 02, 2010, 10:37:09 am Yahoo Message Number: 117936"The majority of my camping is in the far northern part of the country in heavily forested areas. The idea just didn't work as well as I had hoped." Good point, Ed. As you know, the majority of my camping is in the southwest, which has more sunshine than most parts of the country (which is one major reason I like it here, of course :-). Heavily wooded areas are always problematic for solar power.Andy Baird http://www.andybaird.com/travels/
Re: Halogen and LED lamps Reply #20 – November 02, 2010, 05:01:56 pm Yahoo Message Number: 117940Hi,We recall you. Hope to see you aga
Re: Amp hours and charging Reply #21 – November 02, 2010, 05:10:19 pm Yahoo Message Number: 117941On Mon, 1 Nov 2010 09:15:19 -0700, "bumper" wrote:QuoteDon, If you’re making ends meet most of the time electrically speaking, then I’d do nothing until and unless you are boxed in one way or another and have identified what your real shortcomings and needs will be.Yonder has: 400 watts of solar that nets 25 amps (boosted) to the batteries regularly. 450 amp hours of battery bank. Prosine 2000 with programmable 100 amp 3 stage charger, so running the gen-set when necessary (not often) is an efficient way to charge batteries. Note that 100 amps is understating things, as initial rate is over 110 amps.bumper Thanks for all of the input from many. I am still chewing on it. But it looks like doing nothing may be the best course as we only run low on amps when we camp under the wonderful firs of Oregon.However, another option has been revealed to me. We could swap KoKo for Yonder when we next go to Oregon. Tell you what bumper, throw in your macerator destructor toy and we will swap with you. I pledge to only use it for evil purposes.Cheers, Don
Re: Amp hours and charging Reply #22 – November 03, 2010, 01:52:13 am Yahoo Message Number: 117945I "third" this recommendation. With three years of LD/RV experience and extensive boondocking, I am grateful to this group for recommending two critical monitors: battery and See-Level II (for tanks). Also watch cab gas tank gauge to be sure there is sufficient fuel above 1/4 tank to run generator if necessary. These monitors are the boondocker's best friends. You know exactly where you stand with your most critical systems for boondocking. FYI, we were shocked to observe how much power the fluorescent lights draw. Ted
Re: Amp hours and charging Reply #23 – November 03, 2010, 11:04:54 am Yahoo Message Number: 117946"Also watch cab gas tank gauge to be sure there is sufficient fuel above 1/4 tank to run generator if necessary." Good suggestion, Ted. A related idea: my habit is to never let the gas tank get below half full, and to always top off the tank just before pulling into a campground. That way I begin each stay with plenty of gas for generator use, if necessary.Andy Baird http://www.andybaird.com/travels/
Re: Amp hours and charging Reply #24 – November 03, 2010, 04:47:54 pm Yahoo Message Number: 117953On Mon, 1 Nov 2010 09:15:19 -0700, "bumper" wrote:QuoteProsine 2000 with programmable 100 amp 3 stage charger, so running the gen-set when necessary (not often) is an efficient way to charge batteries. Note that 100 amps is understating things, as initial rate is over 110 amps. I recall reading of your Prosine back in 2007. At the time, I thought it was a 2000w sine wave inverter. Nice, but not something I really needed. I later came to understand that if you knew how to wire in a transfer switch, it could become a "whole house" inverter. Even better, but without a clue how to wire a transfer switch, I again passed. Still later, I understood it replaced the charger. OK, fine, but meanwhile I had replaced my charger with a Intelliwhizze or whatever they are called.I see the Intelliwhizze put out an initial 45amps from either the genset or the alternator, but it QUICKLY drops down to 20amps and then to 10-15amps. It takes an hour or two to stuff the first 20amps of a 30amp discharge back in. I never bother with the last 10amps, 5%, as it might run for many hours.So now I understand that with a Prosine I could have around 100 charging amps for a long period? ? ? ?Cheers, Don
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