I know this question has been asked time and time again so here goes we have a electric fridge,2 TV's, the normal lighting all LED's,micro wave and I am installing a 2 burner induction cook top 110v diesel fired heat and on demand hot water from the heating system.
I am redoing the system to be more manageable it's setup with 2-12volt battery bank ea with 3- 8D batteries in ea bank then they tie together for the 2- 24v stacked 4000w inverters for 8000w of AC inverter power.
I want to remove 1 inverter and drop it to 4000w which should be plenty shouldn't it ? now how much battery bank would I need for 2 days of camping without the generator.I have a Lifeline rep helping me, some things he tells me makes sense and some are just goofy. What works best or you guys ?with about the same equipment
What's your plan for the other inverter? Free bump for this thread
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Hi Cliff,
As I'm sure you already know that this is a very tough question to answer, if even possible. I get this question ALL the time when installing solar. There are some reasonably constant variables, but most are hard to predict on-going.
The fridge for example is fairly constant, depending on ambient air temp and fridge type, some are more insulated than others. Here is a link to a worksheet http://www.wholesalesolar.com/solar-information/start-here/offgrid-calculator#applianceTable (http://www.wholesalesolar.com/solar-information/start-here/offgrid-calculator#applianceTable) Its not perfect by any measure but it is a good way to visualize the loads. I would agree you could probably make due with 4kw inverter, depending on surge capacity. Inverters are kinda like generators, they are more efficient depending on load. With that said 6 Lifeline 8D @ 210Ah = 630Ah @ 24Vdc Depending on how long you want your batteries to last you choose how far to discharge them. Off-grid solar for example for longevity I would say discharge to 70% and the batteries will last many years if taken care of (up to 15 years). However, MOST people will destroy batteries much sooner as the care and feeding become tiresome. With that said, figuring that if you get 5yrs out of a set, you will be lucky as inverters are severe duty for batteries. Especially in an RV situation. I have a similar size battery bank, I plan to use 60% discharge, but will probably go to 50% as I'm realistic about what to expect for battery life. In other words don't choose 70% (30% Discharged) because the batteries probably will not last beyond 5yrs anyway, so you might as well get good use of them. OK, so back to the numbers. 630Ah/ 50% = 315Ah (7560w) to work with. That will certainly power a fridge for two days, throw in the microwave now and again along with some instant hot water... Speculating here, but I think you should be good, as long as there are not too many constant draws. Make sure to put a balancer between the two 12V banks, you will get uneven banks when discharging down to 50% and when heavy loads are used.
Jeff
Cliff,
Go with 6 or 8 of the L16s. They will last you a while. 8 of them will get you over 1200 amp hours at 12v. You can live like a king for 2 days in the desert. If you go with the lead acid they are 300$ a piece. That's about 2 bucks per amp hour.
Just drove past your house in AZ today. Waved out the window as we passed. Not sure if you saw us or not...we were moving pretty fast at 75 :)
-Sean
Shanksy, hoping to see you guys in April :) so, $300 times 8 batteries $2400 and they last 5 years? I'm thinking $2400 every 5 years....I could just run off my generator and call it a day. Forget the batts. Yikes.
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Quote from: Scott Bennett on February 10, 2016, 05:24:16 PM
Shanksy, hoping to see you guys in April :) so, $300 times 8 batteries $2400 and they last 5 years? I'm thinking $2400 every 5 years....I could just run off my generator and call it a day. Forget the batts. Yikes.
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Scott - They would last you 10 years. Think of how little you would ever cycle through them. And really if you take good care of them they could last longer than that as long as those plates don't get all eaten up.
Headed to Texas now. Be there by Sunday.
-Sean
Why no solar? Some's better than nothing, and for less than $1 a watt it's affordable. Harvesting the sun makes sense where the sun shines most of the year, i.e the Southwest.
John
QuoteScott - They would last you 10 years. Think of how little you would ever cycle through them. And really if you take good care of them they could last longer than that as long as those plates don't get all eaten up.
Below is a link to a data sheet for what I would consider top-of-the-line batteries
Note the expected life of the Gel or AGM is about 4-6yrs @ 86 degrees service temp, 2-4yrs at 104degrees, unless you live and play 2 miles from the coast or stick to the Northern states 10yrs of service is highly unlikely.
https://www.victronenergy.com/upload/documents/Datasheet-GEL-and-AGM-Batteries-EN.pdf (https://www.victronenergy.com/upload/documents/Datasheet-GEL-and-AGM-Batteries-EN.pdf)
Perhaps, some of you long time bus nuts can comment on how long your house batteries have lasted. If anyone says >10yrs please provide the recipe you used for success, including percentage of usage, and discharge limit.
Solardude.
Quote$300 times 8 batteries $2400 and they last 5 years? I'm thinking $2400 every 5 years....I could just run off my generator and call it a day. Forget the batts. Yikes.
I agree that batteries are crazy expensive currently. If I had to buy another set I would think about buying a Chevy Volt battery pack from a junk yard and splitting it up for about $2400 but the battery would be orders of magnitude more energy dense than the current AGMs.
Here is a look inside the Volt battery. https://www.youtube.com/watch?v=00tTckGUv7I (https://www.youtube.com/watch?v=00tTckGUv7I)
I would run 4 L16 (@ 400amp/hr ea) that would give you 400 amp/hrs at 24v. Have automatic start on the genset-and just make sure the generator is extremely quiet with air bags under the mounts.
I have 2-8D AGM. I simply run the genset 2hrs in the morning and 2hrs after dinner. Lots cheaper, and less weight than a giant bank of batteries. Good Luck, TomC
If you are using the inverters for your change over from gen. to shore power, what will you do for change over if you remove one of the inverters?
Jack
A typical modern fridge runs at around 400 watts or less when it is running. Guess at a 40% duty cycle and that is 160 watts per hour, or 7.5 AH at 24 volts nominal through your inverter. TV, lights, fans are almost incidental because you need to size the battery bank to suit the long load (the fridge) and the short high loads (the microwave and the induction cooktop) Microwave is around 1200 watts when running, and the induction cook top is around 1500 watts per burner when running. Presume you need to run both at once, plus the microwave as you cook your dinner and you have 4200 watts - which is why you maybe want to revisit the dual stacked inverter setup. I would personally ditch the induction cooktop or keep the second inverter, and since you already have the inverter and you know how good the cooktop will be, the decision is pretty easy.
This gives you a short term draw in the 4500 watt range, which is 200 amps near enough at 24 volts through the inverter. Over 48 hours you would be looking at say two hours of cooking, at say half that average rate, so 100 amps times two hours is 200 amp hours. The fridge is 180 amp hours over 48 hours. TV, and LED lights are maybe 50 amp hours. Total (not counting 12 volt loads and fans and pumps) is around 420 amp hours. Using the old 50% discharge rule of thumb (modern AGM and other high tech batteries can go a lot deeper) I would be looking at 800 - 1000 amp hours at 20 hour rate to be conservative.
How are you going to run your air conditioners? This looks mostly like running the kitchen with pretty power hungry devices, and the rest of the coach gets an electrical free ride, almost, but the air conditioners were not mentioned in your note. Other questions I would have are rate of discharge at 200 amps, will that rate hurt or overheat the batteries, and rate of charge. If I ran a bank down to 50% or less I would expect to take at least 24 hours minimum to recharge. an hour a day wouldn't touch it. Running the generator while you are cooking would change the situation drastically.
Brian
I don't plan on running the AC's off the inverters with 5 roof tops it wasn't going to happen any ways.I am just finishing up my dash air which is 45,000 btu they say, I should be good there.LOL ditching the induction cook top is not going to happen I lost that battle in the first round.I doubt the cooktop will be used much off the inverters we cook outside a lot
as much as we think we are the boss..... the woman folk run the world !
dave
The simplest and cheapest is lead acid batts, an inverter, and a generator. Start the genny when needed. Solar panels are nice to have, but they only work when the sun shines high in the sky, not if you are parked under a tree, or anywhere in the winter, even down South. Unless you point them at the sun, but that is too complicated on a bus.
Looking forward to see your bus Clifford. Next winter hopefully.
JC
Without doing a full electrical usage budget we're all just throwing darts blindfolded. But based on our experience with a gas range in the coach and an all electric galley on the boat I will say with absolute certainty that you can't carry enough batteries to go two days without starting the generator. And forget about solar making any significant difference.
People who live off grid either dramatically alter their electrical consumption or run their generator. I'm betting on the generator in your case.
Clifford,
Start here for comparison.
Mine have been in there over 12 years now. They are warranted for 8 years in RVs. The initial investment is a bit but
the return seems good to me.
These are in Las Vegas, so no freight for you!
Joe
http://www.ebay.com/itm/Rolls-Surrette-S-550-6V-428Ah-Deep-Cycle-Flooded-Lead-Acid-Battery-FAST-USA-SHIP-/271855690530?hash=item3f4bdca322:g:UV0AAOSwpDdVQmCF (http://www.ebay.com/itm/Rolls-Surrette-S-550-6V-428Ah-Deep-Cycle-Flooded-Lead-Acid-Battery-FAST-USA-SHIP-/271855690530?hash=item3f4bdca322:g:UV0AAOSwpDdVQmCF)
This is what Chris is telling me to do
Use 4-4D 212ah batteries wired in series and parallel for 24v in 1 string that will give me 424 AH and if I use 2 -12v strings I should use something like a Magnum ME-SBC combiner.
i asked about using the L-16 TomC and he recommend the 4-Ds says the L-16 are good batteries but the 4-D's are less costly and have more plates than is why the 4-D's weigh 20lbs more.
Solardude he agrees with you on the heat I need to add a vent and fan to my battery compartment living in a area where temps can get to 120 degrees and about 4 years is what I can expect for the life of a battery.
Then I should not try and charge the batteries in those type temperatures just disconnect the batteries they don't lose many volts over a long period of time. He makes a good point the more AH in a battery bank the longer the generator time to bring the batteries up to a 100% float charge
He is telling me a AGM battery should be recharged to 100 % after use and if not they should be equalized every so often.Now he is wanting to send me the Concorde Sun X extender batteries he says they are the same battery with 1 year free replacement same as the LifeLine
Only difference is the pro rated warranty on the LifeLine that you pay for.Their warranty no longer covers the bulging cases because he says that is caused by heat and charging even with the 5 year pro rated warranty they no longer warranty a battery damaged by heat.
So the question is this correct or is he pulling my leg.
TomC I do have automatic generator start now
Jack it has a manual switch over but I plan on changing to the automatic through the inverter
Joe I wanted to go with your set up with Rolls but I don't have the clearance
thanks for the input guys is this going to work for me or not ? I need to get this behind me and go to bigger and better things ;D
Just an aside, I went with the L-16 batteries because they have a smaller foot print than the 4-d. Not sure why the 4-d batteries cost less as most batteries are costed on the pounds of lead in them; less the warranty cost.
Cliff I highly recommend a load sharing inverter when you change. I have a 24V house and run a Xantrex 4,000W inverter, (8) AGM 8D's. The new Magnum 4024 is a good one as Xantrex is gone now. We run one roof air going down the road as we have a separate house bank alternator to charge the bats off the engine (200A). We dry camp a lot when traveling and do a one hour gen run in the morning and again at night when sitting for days. I have never let my bat bank get below 50%, usually 60%. You might be able to sit for 2 days off your inverter with an equivalant bank if you are careful and all your stuff is LED as long as no a/c and little micro or cooktop use. The fridge is the big power hog. Right now I have 10 years on my batteries and still going strong.
He sent me the info, funny a 212 amp hr 4-D vs a 8-D with 255 amp hr cost 200 bucks more for the 40 extra amp hrs
Clifford you also you have to figure in how many batteries it will take to run all of Sonja's sewing machines too? 50 8D's
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We got a portable induction cook top and like it because you can just put it in a closet or drawer when done and take it outside too. We still have the gas stove inside when needed.
Dave
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Quote from: Dave5Cs on February 11, 2016, 07:30:14 AM
Clifford you also you have to figure in how many batteries it will take to run all of Sonja's sewing machines too? 50 8D's
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Now thanks to you I have another one to deal with ???
His recommendation is probably fine, he probably knows more about batteries than most. 400 AH at 24 volts is about half what I came up with, so you will be able to do about half (either in time, or mostly in using 100% of your cooktop). Should be fine, just keep in mind the total watts from running both burners and the microwave all at the same time exceeds the capacity of one inverter.
Brian
Take a look at the IBE batteries, made in LA for the forklift industry, they are one tough battery, rugged and able to abuse. Thinking of using these when I need to replace my L16's at a off grid place we have down on the coast. Spendy but supposedly worth it. You order/buy by the 2 volt cell.
Quote from: luvrbus on February 11, 2016, 05:16:49 AM
This is what Chris is telling me to do
He is telling me a AGM battery should be recharged to 100 % after use and if not they should be equalized every so often.
How do you equalize those AGMs? Just wondering. Some folk on the NAWS forum (who know way more about such things than I ever will!) seem to think it's not a good idea: http://forum.solar-electric.com/discussion/23055/need-help-with-equalizing-agm (http://forum.solar-electric.com/discussion/23055/need-help-with-equalizing-agm)
John
Clifford that was the wife not me lol. But I did think it was funny.
Dave
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Quote from: Dave5Cs on February 11, 2016, 09:19:22 AM
Clifford that was the wife not me lol. But I did think it was funny.
Dave
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I know you did but I'll get even ;D
Quote from: Iceni John on February 11, 2016, 09:09:01 AM
How do you equalize those AGMs? Just wondering. Some folk on the NAWS forum (who know way more about such things than I ever will!) seem to think it's not a good idea: http://forum.solar-electric.com/discussion/23055/need-help-with-equalizing-agm (http://forum.solar-electric.com/discussion/23055/need-help-with-equalizing-agm)
John
He is telling me a AGM battery should be recharged to 100 % after use and if not they should be equalized every so often.Now he is wanting to send me the Concorde Sun X extender batteries he says they are the same battery with 1 year free replacement same as the LifeLine
DEKA East Penn and Xantrex both told me to never Equalize the AGM. and 14v max bulk, and 13.2 float....
I don't know Donald, the paper work he sent me says 14.4V for bulk 13.3V for float,it's in their instructions documentation when a battery shows weakness charge with a constant voltage regulated charger @ 15.5 V for 8 hrs to equalize it's not needed if you charge the bank 100% every time so he says
Right or wrong, I have never equalized my AGM 8D's in the ten years that I have been running them. Only once in the ten years have they ever been below 50% and that is when some dumb *?@# unplugged the bus at Paradise Coach and they got down to 38% before I came back Monday and noticed it.
LOL I don't know if its right or wrong either Boomer I see they say if not properly charged it voids the warranty so I will follow his instructions.I am not sure about 15.5V for 8 hrs that has to be for a dead battery you would think
Well, I can guess as to why some battery manufactures will waver on the "equalizing" of batteries.
Most all modern batteries AGM, Gel, Lithium are at an "stressed" condition when fully charged. However to get full rated Ah out of any battery, it will need to be "fully" charged. Fully charged is to say that each cell is at max voltage as designed. With that said most all high-end battery chargers made to charge modern batteries will equalize batteries depending on SOC when charging begins, then once specific conditions are met the charger will discharge to a "storage" voltage. This reduces the stress on each cell. This is important to make batteries last the rated life.
There is no harm in not equalizing a battery, you just will not get the rated Ah's out.
As for having 8kw in inverters as some will suggest, I will inject some science and math, and reference the NEC code.
If I remember correctly, even 4/0 wire would not be large enough wire to sustain much over 4kw for any extended time , especially at 12Vdc, not even at 24Vdc, maybe 36Vdc or 48Vdc. So If you are running more than 4kw, extended, (just guessing here) I would guess your wiring is undersized.
Solardude
Quote from: luvrbus on February 11, 2016, 11:34:36 AM
I don't know Donald, the paper work he sent me says 14.4V for bulk 13.3V for float,it's in their instructions documentation when a battery shows weakness charge with a constant voltage regulated charger @ 15.5 V for 8 hrs to equalize it's not needed if you charge the bank 100% every time so he says
those numbers are not that far off... i would just be hesitant to equalize mine ...unless i saw a situation where the capacity was diminishing over a quicker period of time... my current set is now 3+ yo but has also never seen 50%... i figure 5-6 years is a good life. but before i trashed them i would equalize them...just not for 5 hours. i don't think that the trace/xantrex eq parameters ever eq'd my wet batteries that long either... maybe i just don't remember it well :) seems that eq charge really could boil the pisss out of an old battery :)
Lifeline makes many of their batteries in either 6v or 2v. Think about this for a minute-the 6v L16 is 400amp/hr. The 2v is 1200amp/hr. Either way to make a 1200amp/hr battery bank you need to use 6 of either the 2v or 6v. The big difference is, if one of the 2v batteries takes a dump, your battery bank is done. If one or even 2 of the 6v batteries takes a dump, you can wire around it and still go down the road with 800amp/hr battery bank.
The Lifeline tech guy said that 2v batteries are primarily for solar standby power for a house. With mobile, stick to 6v or 12v batteries. Good Luck, TomC
Right now I am trying to figure out why people say a 24v system is better than 12v you need a lot of batteries to get AH's with a 24v system.I don't see a free lunch in any of this stuf
As the volts go up the need for amps go down and so does the wire size.
So a load of 100 amps at 12v only requires 50 amps at 24v and thus a smaller wire is needed
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!2 volts vs 24 volts.
Things use power to work, which is measured in watts. Watts are volts times amps so your 400 amp hour battery bank at 24 volts can deliver 9600 watt hours. An 800 amp hour battery bank at 12 volts produces exactly the same 9600 watt hours. So in terms of what you can do with it they have exactly the same capacity, it's just that the power is delivered at twice the voltage and half the amps. Since at these low levels wire doesn't care what voltage you put through it, but wire does care a lot about how many amps of current you put through it, the big deal about 24 volts is nothing more than it takes half the current to obtain the same amount of power as 12 volts does. This goes everywhere - the wire for sure, but also switches, connectors, solid state devices in the inverters, etc. All of these things can be smaller, and cost less.
Brian
and cost less..... to make. ???
Quote from: bevans6 on February 12, 2016, 02:51:48 AM
!2 volts vs 24 volts.
Things use power to work, which is measured in watts. Watts are volts times amps so your 400 amp hour battery bank at 24 volts can deliver 9600 watt hours. An 800 amp hour battery bank at 12 volts produces exactly the same 9600 watt hours. So in terms of what you can do with it they have exactly the same capacity, it's just that the power is delivered at twice the voltage and half the amps. Since at these low levels wire doesn't care what voltage you put through it, but wire does care a lot about how many amps of current you put through it, the big deal about 24 volts is nothing more than it takes half the current to obtain the same amount of power as 12 volts does. This goes everywhere - the wire for sure, but also switches, connectors, solid state devices in the inverters, etc. All of these things can be smaller, and cost less.
Brian
In theory but because there is a smaller 24 volt market the price goes up.
Military vehicles. European buses and trucks are all 24v. US trucks and some buses are 12v. Good Luck, TomC