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rmak
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# Posted: 23 Dec 2013 21:45 - Edited by: rmak
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We built our small (12 X 16) cabin on our property. We have 9 acres and we are surrounded by woods and fields. Our intended use for the cabin is purely recreational. Since we have two boys with disabilities we want to be able to get away but be close enough to our home in case we are needed.
Anyhow, I am planning to go solar for power. My problem is that outside of a few lights and plugs there is really no big need for electricity. We can bring coolers and cook out. We can make coffee at the fire pit in the summer and woodstove in the winter. Extra power would be nice, but not a necessity for survival.
I've been talking off and on with the guys at AltE about solar cabin kits. I always get frustrated because they always want me to do a power calculation. I always say that I'd like to have some electricity but since I've never had power in the cabin before I really don't know what I will be using. I just want a recommendation. AltE doesn't want to do this. I understand that once you buy the components it would be costly to upgrade later. That might be the reason for their reluctance to pick a kit for me.
My problem in calculation is that when I go through the list it's all speculation. Will I ever want to run a vacuum cleaner? I don't know. Maybe. If I can't run one and need one I can use generator power or get a cheap rechargeable. I go through this exercise with all the appliances on the list. It's all maybes.
I'm sure if we had excess power we could use it when we are using the cabin. On the other hand, if we don't have the power to run something we can make do.
I thought maybe if I asked here, someone would have a similar situation and be able to make a suggestion to me. I am thinking now about just buying the 280 watt kit for around $2,300. I figure that would give me plenty of lights and plugs and I will see from there. I also intend to get a small generator if we need one.
I'm also thinking about doing solar to some extent on our home. I think setting up the cabin will be a good learning experience for me.
Any suggestions or advice would be appreciated.
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MtnDon
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# Posted: 23 Dec 2013 22:27
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Quoting: rmak I've been talking off and on with the guys at AltE about solar cabin kits. I always get frustrated because they always want me to do a power calculation............... I really don't know what I will be using. I just want a recommendation. AltE doesn't want to do this.
1. I agree 100% with the vendors request for you to do a audit/estimate of what you might use. And I agree with their refusal to make a recommendation based on no real facts. I would not want to apply my guess either. If I guess low you'd be ticked off about the system "failing" to perform. If I guessed too high you've spent too much money and would likely be ticked about that too. It's a no win situation for them, IMO.
Nobody can guess for you and be sure to make you a happy camper. I took months and went through several different estimates before I was satisfied I was on the right track. A somewhat hidden danger of erring and building too large a system is not only the extra un-needed expenditure. A system that under utilizes the battery capacity can actually shorten battery life. Not as much as designing too small and constantly over discharging the batteries.
You do the first step, it is going to be your system. Estimate as accurately as possible what will be used and for how many hours a day. Some things like a water pump may be only minutes a day. As well as what and how long you need to research the amount, the watts used. I believe Alt-e has an online calculator that can help.
Going back to the beginning for a moment... How much will the property be used? How frequent and for what length of time? It may make more sense, if the use is light, to have a system as simple as a battery and a small Honda/Yamaha inverter-generator and no solar at all. Or just a battery or two that you haul back and forth and charge at home after the weekend.
Any system anyone suggests stands a 50/50 chance of being wrong if you have no input for power use estimation.
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creeky
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# Posted: 24 Dec 2013 09:03
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You're in the same boat as many folks who go off grid for the first time. welcome. 
Someone on the site recommended Solarblvd to me. They have a 240 watt solar system. pretty good quality. for 750. the 360 watt system would probably push a microwave. amazon also has some inexpensive systems.
That and two 6v lead acid batteries. for 240 amp/hrs at 12v. and you're on your way. that'll do lights etc.
This way you can do a simple system and learn more about your needs while actually making power.
A small genny will power bigger loads like a microwave or water pump if required. But a simple 12v system will allow you to have lights, a 12v water pump for showers, dishes etc.
Don't be afraid to experiment. Going off grid is fun and learning is never a bad thing. Even if it is from our mistakes sometimes...
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rmak
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# Posted: 24 Dec 2013 09:18
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Thanks MtnDon and Creeky,
I'm not sure about how much the cabin will be used, which is another question mark. My wife and I are both near retirement age. As you can imagine that opens up a whole new can of worms about what we will be doing and not doing.
I like the idea of buying a cheap entry level system and going from there. A generator is a definite.
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MJW
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# Posted: 24 Dec 2013 09:30
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rmak...if I were you and there are still things you want to work out before making a decision on the solar...I would just pick up a Honda EU2000i and go with that until I got it all figured out.
We run our entire place on one. Lights, TV, fridge, freezer, coffee maker, appliances and the occasional vacuum.
You say you are going to pick up a small generator anyway and doing this would solve your problem giving you more time to actually figure out what you will be using and how much.
Once you have it all figured out, you can buy a system that meets your needs and have your generator for those times you may need "extra."
Merry Christmas!
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rmak
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# Posted: 24 Dec 2013 09:44
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Thanks MJW.
My biggest problem with full generator power is the noise. I want to get away from noise. I was hoping to have a solar system with batteries converted to AC and use the generator to charge the batteries so it wouldn't be on all the time.
Am I thinking clearly about it?
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GomerPile
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# Posted: 24 Dec 2013 10:22 - Edited by: GomerPile
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Here is how my off grid house is powered:
*** 3 Tier Approach ***
Tier 1: Low voltage DC. Will run lights, charge phones, run a DC fridge etc
Tier 2: Medium Power AC 300-1000W. Can be used to run a small micriowave, water heater, or other small AC appliance
Tier 3: High Power AC up to 2000W.
My tier 1 is a bank of two 122 amp hour deep cycle batteries from Walmart (yes walmart). I run everything I can off this tier. My daily consumption is 8-10 amp hours. It will be 20 amp hours in spring when I add a Sundanzer fridge.
Recharging my battery bank is done with 3 PV panels (50w, 70w, 100w = 220W) connected via a PWM charge controller. In the spring I plan to add two more 100W panels and an MPPT charge controller. I'm going to remove the 50W panel and use it to power a backup battery system so I will have 370 watts in my main PV array which need to supply me 20 amp hours per day (easily done and then some).
Tier 2 is a 600W sine wave inverter connected to my battery bank. It powers my water heater and a couple other odd items (on demand...its never on unless being used).
Tier 3 is a Honda EU2000 generator that I use to run a washing machine and/or a battery charger.
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rmak
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# Posted: 24 Dec 2013 11:13
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Thanks Gomer!
Can I have the generator charge my batteries so I don't have it on all the time? Can I integrate into a small solar set up so I can capture that power too? I'd like just one set of lights/plugs run on ac so I can power a few things, radio, etc. I'm sorry I'm so ignorant of this stuff. I guess I'm a slow learner.
Do you guys keep the generator inside (when not being used)? I have such a small cabin that I'm wanting to build a small box outside to protect it to save storage space.
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toyota_mdt_tech
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# Posted: 24 Dec 2013 13:45
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Quoting: rmak Thanks MJW. My biggest problem with full generator power is the noise. I want to get away from noise
Have you listened to the Honda EU2000i yet? Its so ridiculously quiet, you will hardly even know its running.
You can buy an RV charger,
(here is a link to a nice unit)
http://www.pplmotorhomes.com/parts/rv-converters/inteli-power-9200-converter.htm
So when you are running the generator, its also charging your batteries. This can be in addition to your solar set up. So while you are trying to figure it out, you can be up and running in the mean time as with what others mentioned, you planned on a generator anyway. Once you hear (or dont hear) a Honda EU2000i run in eco mode (where mine runs all the time) you wont be able to get your wallet out fast enough to buy it.
Then when you set up your solar system, just tie it into the battery bank.
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GomerPile
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# Posted: 24 Dec 2013 14:35
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I use a plain old car battery charger and when needed attach to my battery bank.
I do laundry on weekends and need to run the generator. I often queue up all my AC stuff for that 2 hour window of generator operation. I top off my laptop, charge the house batteries if needed, etc.
If you just want "one set of plugs" you can't copy my system. I split mine up to make most efficient use of power. Think about this an inverter uses 6 watts of power when turned on. If you power an 8W LED lamp for 5 hours each night thats 10 amp hours wasted over the span of a week. My daily consumption is 10 amp hours....over a long stretch of cloudy days thats a days worth of reserve power wasted every 5 days of operation.
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rmak
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# Posted: 24 Dec 2013 16:15
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Thanks Gomer!
I've been too busy with Christmas to look at your system. My biggest problems with multi plugs is looks. I've got to run conduit inside the cabin, or maybe that nicer inside plug/wire cover stuff. I'd like to keep it to a minimum. Secondly, others will be using the cabin from time to time and I can see wrong plug problems.
Maybe lights on DC.
So you just hook up a battery charger into the generator to charge batteries? That's cool.
I'm still wondering if I could make an outside box for the generator. Is that what everyone else does?
Getting back to solar. If I bought a kit, is it easy to install myself? I got mechanical and construction know how, but outside of house and motorcycle wiring I'm not Mr. electronics.
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Truecabin
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# Posted: 24 Dec 2013 22:09
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start simple dont waste a lot of money
id get an inverter that has a big battery charger as part of it so anytime you are running the generator its charging
run the vacuum while the generator is on you wont hear a thing
solar people use there batteries only 10% which means they buy 10x as much batteries as they need
if they know that why not buy only 10% of the batteries then use that one battery 100% like everyone else? i dont understand it a big battery bank gets 6 years old just as fast as a small battery bank but it cost a lot more so where is the sense?
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MtnDon
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# Posted: 25 Dec 2013 00:33
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Quoting: Truecabin solar people use there batteries only 10% which means they buy 10x as much batteries as they need if they know that why not buy only 10% of the batteries then use that one battery 100% like everyone else? i dont understand it a big battery bank gets 6 years old just as fast as a small battery bank but it cost a lot more so where is the sense?
Battery lifespan vs. depth of discharge, From Rolls Battery Engineering....
and below is a graph from Rolls. Lifespan measured in number of discharge / recharge cycles.
rolls 5000 series DFoD vs Lifespan
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Truecabin
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# Posted: 25 Dec 2013 15:48 - Edited by: Truecabin
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solar people say to use only the top 10%
the site you posted says its most practical to use 30-40% which is 2-3x the batteries you need
that makes more sense to me
if you buy batteries to use only 10% then you have to buy about 3x as many batteries as if you are ok with 30-40%
and maybe they dont last as long but your scrapping 3x not 10x thats a big cost and a big waste too
you have to hope battery technology is better at the next time you need batteries but you can never know maybe the price of lead goes thru the roof....
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MtnDon
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# Posted: 25 Dec 2013 16:01
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If you have talked / corresponded / read onfo, from solar people and they have said only use 10%, I would make a note to never deal with or listen to them again. The couple of "experts" I know have usually picked 20 to 25% as an ideal daily rate. Going to 50% has often been touted as a "next to" ideal amount as that makes it easier for many to afford the batteries they need.
I went with an aim point of 25% and we usually do better than that.
I'm not holding my breath for cheaper batteries.
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Truecabin
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# Posted: 25 Dec 2013 16:58 - Edited by: Truecabin
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ok thx
so in the morning if you have between 12.1v = 50% and 12.4v = 80% then you have a good number of batteries
start with the fewest batteries then you can buy more if you need more but try to figure it out in the first few months how many batteries you need so you dont mixnew batteries in with old batteries
maybe a good time to start is in the winter when you might know your max usage sooner
if you add batteries you may need to add a panel or two so leave some room for more and make sure your components have capacity for more panels too
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rmak
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# Posted: 25 Dec 2013 18:21
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So, since I'm asking for "simple" advice, I should make sure the solar power system has components that can charge the batteries with a generator, and will allow for expansion in the number of batteries and panels. Is that correct?
I'm going to call the Solarblvd company recommended early in the thread. The $750 kit rated at 280W looks good to me.
I can buy that kit and a generator and not completely break the bank. Can anyone see a problem with this kind of a set up?
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GomerPile
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# Posted: 25 Dec 2013 21:40
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I would not rely on voltage measurements to determine battery capacity. Get a system monitor of some kind...I use a xantrex linklite...there are many brands.
If you can afford it look into MPPT charger. I'm thinking it's even ok to skimp on panels if you do an MPPT charger as it makes more efficient use of the power your panels produce.
In the spring I will be upgrading to a morningstar unit. Incidentally, the better MPPT chargers include a system monitor. You need to look at total system cost when you evaluate that option.
As for the battery depth of discharge issue. As you can see from the chart lower depth of discharge means longer life. Personally I want to be at no more than 10% DOD but sometimes you get a cloudy stretch. Yesterday I was 70 amp hours down on my 244 amp hour bank...it's not the end of the world. I use cheap ass batteries and have small loads YMMV.
Pick a reasonable DOD number like 25-50% and then spend money on more efficient devices. Buy a solar fridge, led lights, DC water pump, smaller microwave. Also look at lifestyle factors....can you eliminate the microwave and use the stovetop instead? Can you cook toast in the oven rather than use ann electric toaster? Do you really need a hair dryer when a hat will do? Questions you personally need to answer.
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GomerPile
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# Posted: 25 Dec 2013 21:46
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The kit you mentioned on solarblvd uses good quality components from morningstar....great getting started kit. That inverter probably the best one you can buy in that size (300w).
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spoofer
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# Posted: 26 Dec 2013 08:39
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I have a 14x24 ft cabin in northern ny. I power my cabin with 1 boat battery all weekend long. I have 3 fluorescent lights a radio and a small 19 inch led tv. The battery will last ok if I am careful about my power usage. Renogy has a 100 watt solar panel on Amazon with all the other necessary components for about $200. I figure this is all I need for constant power as long as I bridge another deep cycle battery to this set-up. That way I won't have to bring the battery home to charge. I also have a small el-cheapo generator if I need to power a tool etc. I would start small like this for a fews hundred bucks. You can always add to this system later.
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old greybeard
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# Posted: 26 Dec 2013 10:01
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For a small off grid low wattage cabin its very easy to buy and install your own components. I have two 80w panels feeding individual PVM 30a charge controllers. Each controller feeds a 4d battery.Gives me redundancy. I run a 12v system and am wired for 120v using a 700w inverter or a generator. Usually use the generator 4x a year, on those rare occasions my wife needs a hair dryer or wants to vacuum. Plenty of power for a 20" HDTV, cfl lights and radio. Even with snow on the panels I have plenty of power, usually only up every other weekend in winter.
Panels are so cheap now:
http://www.amazon.com/RENOGY-Monocrystalline-Photovoltaic-Battery-Charging/dp/B009Z6C W7O
With wood heat, propane fridge, heat and stove. With my limited electric needs I could live off this year round, but would have to clear snow off the panels in the winter. And hand wash laundry
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rmak
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# Posted: 26 Dec 2013 11:15
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Thanks Spoofer and Old Greybeard.
I am still confused about adding on to an existing solar system. If I start off with one or two batteries and the other conversion parts to a kit, can I add batteries and more panels to what I get originally or do I need to upgrade the other parts of the system as well?
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spoofer
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# Posted: 26 Dec 2013 15:31
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rmak
you would just have to upgrade the charge controller as you added more panels. or you could buy a little bit bigger charge controller when you purchase 1 panel in anticipation of adding another panel. I am thinking about buying the Renogy 100 panel for my cabin after the holidays are over. If I buy directly from the co. I can order a C.C. that would handle a 300 watt panel system system in case I upgrade.
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VTweekender
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# Posted: 26 Dec 2013 17:13 - Edited by: VTweekender
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Quoting: rmak I am still confused about adding on to an existing solar system. If I start off with one or two batteries and the other conversion parts to a kit, can I add batteries and more panels to what I get originally or do I need to upgrade the other parts of the system as well?
It all comes back to the original refusal from that company to advise you on what system......without knowing exactly what you are going to plug into it it, it is impossible to answer these type questions......As it sits, the system you are looking at will run a couple small CFL bulbs and a small TV...thats about it...which is great if thats all you want to do....the 300 inverter in that kit will not handle any more than that...the charge controller is almost maxed out with the solar panels with the kit....
If you are pretty sure you will plug more items into the solar system in the future then the only sensible thing would be to go bigger right in the beginning..
For example, if you have a 20 amp charge controller, the max input to it from your panels will be 20 amps, a 100 watt panel puts out about 5 amps, so that controller is maxed out with 300 to 400 watts of panels.....
For example for the inverter, a 300 watt inverter means it will turn DC current into 300 watts of AC current, a small microwave is 700 watts, you would have to forget a small microwave with only 300 watts put out with that inverter.....you would need a 1000 watt inverter to run a small microwave because at start up there is a surge ....
hope this helps
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MtnDon
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# Posted: 26 Dec 2013 17:43
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Quoting: VTweekender a small microwave is 700 watts
What you see on the box is the cooking power in watts. The microwave will use more watts of electrical power than that while cooking. That is sometimes hard to find, depending on the make. EG: Our big home microwave is rated at 1100 watts cook power; it draws 1550 from the electric system. The small one is rated 700 watts and draws 1000 watts.
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rmak
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# Posted: 26 Dec 2013 18:33
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Ha, ha! I love you guys. Some of you want me to start small with a car battery and add on, others want me to go bigger than a $750-280 watt kit.
I'm not trying to be rude or contrary to anyone. I do appreciate all the suggestions and advice. It just seems like solar is not a subject for simple answers.
And I realize it's probably my being spoiled by a lifetime of almost seemingly limitless power that makes evaluating real energy outlay hard.
I'm still leaning towards the 280 watt kit and a generator. As I said, it will be a learning experience for me and I'm bound to make mistakes. Hope to someday be able to talk about this stuff with a lot more knowledge.
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Dillio187
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# Posted: 26 Dec 2013 19:51 - Edited by: Dillio187
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do NOT add on batteries. Your entire battery bank should be identical batteries of the same age, so buy them all at the same time. Batteries age, and if you add new batteries to an old bank, the new batteries will age to match the old batteries.
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spoofer
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# Posted: 26 Dec 2013 20:00
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good info dillii
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Truecabin
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# Posted: 26 Dec 2013 22:47
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>>> if you add new batteries to an old bank, the new batteries will age to match the old batteries
if you buy 4 batteries now then in 8 months you have 4 batteries that are 8 months old but maybe youbwasted money on too many batteries
if you buy 2 batteries now, then 4 months later after you know your needs then buy 2 more. after 8 months you have 4 batteries that are 8 months old
in some cases its better to buy more panels you can aim one for morning and one for afternoon
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MtnDon
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# Posted: 27 Dec 2013 00:33
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Personally I do not worry about age differences of only a few months. There are differences between batteries that come out of the same batch, so an age difference of a few months is of no concern. The batteries should be the same make and model.
If the owner gives the batteries reasonable care; keeps the fluid level up, does not deeply discharge regularly and recharges them to full nearly every day they are used, golf cart batteries should easily last 5 years. maybe more if the DoD is kept to less than 40-50%. A few months difference then will hardly cause a blip.
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