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TomChum
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# Posted: 10 Feb 2012 12:31pm - Edited by: TomChum
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My first version of this was a little steel dolly that allowed me to roll 2 T105 batteries (66 lbs each) in/out from under the cabin. It didn't work well due to the soft soil. And then I added 2 more batteries for a total of 4 (=264 lbs of batteries). At 172sf, my cabin does not allow a lot of storage, and I don't like stuff laying around the cabin (.....have too much junk laying around at home !)
I finished the basic parts of this project over the last few days. It's a sliding drawer that hides the batteries and inverter under my little cabin, but slides out on heavy-duty sliding door rails for maintenance, to add water, etc. The rails are 6 feet long each, and hang on four 4-wheel trolleys that are lagged upward into the floor joists with 1/2" lag bolts. The drawer is heavy itself, made of rough-cut 2X6 doug fir, and glides about an inch over the ground. Inside size is 24"x24", which leaves room for 2 more batteries. When it's out all the way it rests upon the ground, carrying 264 lbs of batteries. I'm pretty sure it's going to require a permanent "rest", at the extended position, which I'll figure out later.
Next step is to build proper cabling. I have some large flexible welding cables that I will route into the box. Also I will cover all metal with wood so it blends into my decor, and offer some theft protection too. But then I started reading up on battery boxes (....doing the research AFTER starting the project) and found several things to change and I'm sure there will be more to come.
For example:
- Move all electronics away from the batteries
- A (corners folded) shower liner to contain acid spillage
- Insulation?
Well anyway .... here are some pictures of where the project was yesterday.
Original battery dolly for two T105 batteries
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Sketch of battery drawer plan (built it 24x24)
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Battery Drawer slid under cabin
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Battery Drawer slid out
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razmichael
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# Posted: 10 Feb 2012 01:16pm
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Hi TomChum
I will be doing something similar next year (mounting my batteries under the cabin) so thanks for the ideas. Those T105s are heavy! Don't forget to add "venting" to your list of things to note (although your system will not be sealed so should not be an issue). Also, depending on how you plan to wire up four batteries (12 volts, 24 volts?) take a look at this site for some interesting information on how to best wire up multiple batteries to balance them SmartGauge. This is the first time I have seen this information with some actual testing and figures to back it up. The batteries are not cheap so a few extra dollars in cables may be worth it. My system is wired with 2/0 gauge so the cabling is not cheap either!
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TomChum
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# Posted: 10 Feb 2012 02:53pm
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Balancing batteries - thanks very much for that timely and well explained information. I will be making my cables next, and it's a good thing you shared this before I started on cables. I've saved (save as...) the page contents on my hard drive in my "cabin electrical" folder so I can read it at the cabin, also if the website goes away I still have it.
Thanks again!
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MtnDon
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# Posted: 10 Feb 2012 08:18pm - Edited by: MtnDon
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I like your slide out.
For connecting give some thought to buss bars and straps made from solid copper bars stock. It makes it very easy to remove a battery or a series string from a parallel setup. No disturbing the other batteries.
The buss bars could be on the sliding tray and connect to the balance of the system with flexible welding cables.
Google Storm Copper for pricing on all sorts of copper. They ship fast.
That is my battery bank.
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TomChum
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# Posted: 10 Feb 2012 08:39pm - Edited by: TomChum
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Hi Don, Thx for the pic. That would be a clean setup on my drawer......but it would be a lonely bus bar!
With only 4 batteries I make 2 jumpers and I'm done.
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Martian
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# Posted: 10 Feb 2012 08:51pm
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Have you given any thought to the risk of fire? Batteries do catch on fire.
Tom
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TomChum
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# Posted: 10 Feb 2012 09:05pm - Edited by: TomChum
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I've heard that but never seen any real 'evidence'? There are a lot of batteries in a lot of cars, enough that I think I would have heard of a 'genuine event' over time.
Conversely almost every history book I pick up tells of a cabin or a hotel or lodge burning due to oil lamps.
I guess if there was some failure of my cables they could burn their insulation and perhaps ignite wood. maybe I should put a sheet metal ceiling to cover the floor joists.
I wonder how long a battery burns, and what actually burns? Thanks for the note though, there sure is lots to consider!
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Martian
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# Posted: 10 Feb 2012 11:37pm
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I have seen them melt and deform from overcharging due to a faulty charger, but I've never seen one actually catch fire, either. The case is plastic and will burn. Like you, I'd be more worried about some critter chewing the wires and shorting them out, but if you have a master fuse on each battery as recommended, then the wiring should be protected. If you don't have maintenance free batteries, they will gas while charging. The gas promotes wood rot and is explosive if contained. I like the idea of putting some heavy guage sheet metal above the batteries.
Tom
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TomChum
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# Posted: 12 Feb 2012 02:30pm - Edited by: TomChum
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Quoting: Martian worried about some critter chewing the wires and shorting them out
Good point. Route cables as if they were bare, such that insulation adds safety but is not a necessity, and as short as possible.
Here's a diagram of 2 (4 x 6v) systems. (Pair1 =2 years old, pair2 = 1y.o.)
-->Left pic is wired for 12v, but unbalanced, (back battery is 'uphill')
-->Right pic is balanced (with shorter cables too), a simple and easy fix for 4 6v batteries @12v. I intend to maintain the 'pairs'.
I have my system in 'unbalanced' configuration currently. The 'front' battery pair uses significantly more water than the 'rear' pair - which suggests that the front pair is doing all the 'work'.
Four 6v batteries, 12v system, Balanced
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MtnDon
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# Posted: 12 Feb 2012 04:00pm
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You should notice a difference unless the batteries that are using more water also have some internal problem. Our 3 parallel strings of 4 in series, connected to the bus bars, show no differences in water use or sp gr readings.
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TomChum
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# Posted: 12 Feb 2012 06:11pm
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.... interesting! My "2nd pair" was connected for most of their life (the last year) with 8-foot automotive jumper cables. I suspect that when the generator was running not much made it out to the 2nd battery.
My system may not be 'steady-state' enough to draw such conclusions. I'll pay attention to the water consumption with all proper cabling.
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Martian
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# Posted: 12 Feb 2012 06:46pm
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On the boats, we charged thru battery isolators to help avoid one battery bank pulling all the charge.
One of the responsibilities of the repair yard manager, me, was to write a maintenance article for the local sailing rag each month. My closing tag was, "Remember to check the water in your batteries." Many boaters would comment on how nice it was to be reminded each month. It saved many a battery from premature death.
Tom
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fred
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# Posted: 14 Feb 2012 02:26am
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I really like the drawer idea. Thanks the links Gentlemen. Great info and the link to pics of your megabank MtnDon. I'd think about mounting my batteries out or under the cabin but I'd lose quite a bit with the cold temps here in Colorado at 8000'. I plan on setting my 4 in an insulated and vented box in a utility/ bathroom. Hopefully they'll stay above 60 degrees even when it's below zero.
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TomChum
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# Posted: 14 Feb 2012 03:21am - Edited by: TomChum
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With cold you lose capacity, but the cold actually preserves a (charged) battery. I read somewhere that at zero degreesF you have about 80% capacity, so in the cold your battery bank is effectively smaller.
It sees to me that if you're not cycling the battery (for example not using the cabin) then you might as well be 'preserving' the batteries, extending their life, by storing them in the cold. Fully charged, of course!
correct/wrong?
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TomChum
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# Posted: 13 Mar 2012 01:57am - Edited by: TomChum
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Well well, I just stumbled onto a large amount of 4/0 copper wire. For my battery box I have a 30 foot section of super-fine stranded cable (from a buzzbox welder). I made my own terminal ends from 1/2" copper pipe (the thick-wall, outdoor pipe, "blue-stripe") because I couldn't find any 4/0 terminal ends with small 5/16 eyeholes. 4/0 is a big wire. Plus the terminals cost $5 each, (x12= $60 in terminals alone)!
I found an old tool in a junkpile and welded dies (1/2" iron pipe, split in half) on to tightly hold the 1/2" thickwall (outdoor) copper pipe. 4/0 wire fits just right in the copper pipe, and I'll smash it flat to make the terminal ends. A rounded pin on a spring/hinge (bent flatbar) will make the crimp.
I clamp the visegrip hard on the pipe, then pound the tool with a hammer to drive the rounded crimp pin in.
Here a test-terminal pounded once.
Here is a finished terminal. The copper pipe length is 2 1/4" I move the crimper up and down the terminal and make a wide crimp. I've filled the crimp cavity with 'goop' so when I wrap it with self-fusing rubber tape it will be well sealed.
Here it is, wrapped with self-fusing rubber tape.
Well, off to the cabin to install my cables. We are supposed to get 12"+ snow this week!!!
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Mtnviewer
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# Posted: 13 Mar 2012 05:19pm
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I don't know if the temperature relationship is that simple. The battery may have 80% capacity at ambient freezing, but since you should not draw your batteries below 50% capacity, how much capacity do you really have left to draw from? Not much & no where near 80%. Plus charging cold batteries is at a lower voltage. Plus without a temperature compensated charge controller at the same temp as the batteries, then charging is further compromised. I keep my system inside where it's room temperature in a sealed box which is fan vented to the outside with a low watt Zephyr fan set to exhaust at 26.5 volts (24 volt system). A friend had his batteries in a cold basement for several years while I kept encouraging him to move them inside. He finally did & was shocked at the real world performance & capacity difference. He wasted A LOT of diesel fuel trying to charge constantly cold batteries.
http://www.windsun.com/Batteries/Battery_FAQ.htm
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Stophel
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# Posted: 14 Mar 2012 01:00pm
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I had a car battery blow up in my face! Jump starting. No fire, just black and bubbles. Oh, and burning the cornea of my right eye.... Fortunately, the spot didn't last too terribly long, a few weeks. SEVERE pain though the first couple of days.
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TomChum
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# Posted: 14 Mar 2012 01:13pm - Edited by: TomChum
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Yes that I've heard of. Glad your eye was OK.
Lots of hydrogen coming out of the vents; then "SPARK" of attaching the jumper. If a battery has been charging I always stand back with an arm outstretched and spark the terminals first..... My dad showed me that (and told me when to to it), and it made good sense. If it's been on the charger awhile you should remove the caps so the hydrogen is not in an enclosed chamber. If you're in a hurry I'd blow into the hole to dilute the gas.
My dad had lots of old heavy-equipment and was always milking batteries to the end, consequently as a child I was in the vicinity of many last-leg batteries so this was something I saw often. He didn't like buying new batteries, and also old batteries were easier to keep on the equipment - less likely to get stolen. In those days thieves didn't care much for 'old' batteries (and his batteries always looked 'old').
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TomChum
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# Posted: 14 Mar 2012 01:58pm - Edited by: TomChum
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Quoting: Mtnviewer He wasted A LOT of diesel fuel trying to charge constantly cold batteries.
I need to look into this. Very useful link on windsun.com, I saved it as an archive on my harddrive in my cabin systems folder. I'm pretty sure MtnDon has sent me there awhile ago.
I don't have a warm place for the batteries though. It seems like when NOT being used, that they will preserve longer if kept charged, and cold when un-used. This does not apply to a lived-in house (right?)
Anyway I've been wondering why my charger (inverter/charger) sometimes refuses to charge, maybe because:
1) Generator is too small (honda EX1000)
2) Too cold (~30degF)
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TomChum
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# Posted: 14 Mar 2012 11:36pm - Edited by: TomChum
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Well, Onward with my outdoor battery storage project. Since this is a vacation cabin, and there is no possibility to store the batteries inside for the few days it's heated, the batteries will have to live outside. Most of the year the temp here is between 40 and 70 degrees outside.
But not today, as you can see! Today it's 28 degrees and snowing lightly. Forecast is 3-7 inches but I got one inch.
I decided to take the drawer apart and redo some of it, to hide the steel track better. And to make it "look old".
Also added a brace in the backside because it sagged a little.
My new 4/0 cables installed. I have a little more wiring to clean up. The trained eye will notice a 300A Class T fuse on the positive terminal. Also that this extensive system of "four" batteries is 'balanced' which probably means nothing when such large cables are used.
Here's the Battery drawer a few weeks ago:
The 'new'. ( does it look 'old'? )
Closed up. 66x4 = 264lbs of batteries glides out from under the cabin; 1/2" over the ground. This works great. I'll replace that plastic pull handle with something that looks better, someday when I find whatever it is....
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MtnDon
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# Posted: 16 Mar 2012 07:54pm
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Quoting: TomChum Anyway I've been wondering why my charger (inverter/charger) sometimes refuses to charge, maybe because: 1) Generator is too small (honda EX1000) 2) Too cold (~30degF)
The tray is looking good! Good show on the fuse  !!
By refusing to charge, does that mean simply slow or not at all?
Cold does affect how much can be withdrawn from the battery bank. My experience has been that the cold weather does not seem to affect recharging the battery bank. But it definitely does affect how much power we can withdraw.
That is based on using a temperature corrected hydrometer to confirm the state of charge of the batteries after the charger went into float. It also involved a couple of tests, one in summer and one in winter. One part of the test involved metering the AC power used over a 24 hour period in Kwh. The other part was using the log info from the Outback Flexmax charge controller, specifically the power in Kwh, sent from the charge controller into the batteries, until the charge controller switched to float mode. The in & out numbers do not match and should not be expected to match, as there are losseswhen batteries are charged and there are losses when the batteries give up power and losses in the change from DC to AC in the inverter. What was important to me was to see that there was very little difference in the ratio between power out and power in. It's not a very scientific test as the use was only metered three days in July and three days in February.
The total amount of power used in the summer and the winter segments was close to being the same. The hydrometer reading in the AM, before recharging commenced showed a noticeably lower reading. Sorry I forget the numbers; I did this two years ago. But the state of charge reading after discharge in the cold wather corresponded with the information on Wind_Sun and another source or two I have used.
So yeah, wer have more batteries than we might need if the batteries were kept warmer through the winter, but our batteries should also last longer, everything else being equal.
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TomChum
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# Posted: 16 Mar 2012 10:19pm
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I meant "not at all". The Magnum Energy was not charging the batteries at all (according to the display). It would charge for a moment (just enough to flash the display, then stop. I determined that it was because my (temporary) wires were too small. They had enough resistance that the charger didn't like what it was measuring. So I had to use my car-battery charger instead.
Now with my new HUGE cables, my Magnum Energy inverter/charger showed 57 Amps during bulk charge stage (with the little Honda EX1000). 57x14.4=820watts
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MtnDon
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# Posted: 16 Mar 2012 11:33pm
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stoverr2
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# Posted: 21 Mar 2012 09:28am
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MtnDon,
I've looked through several posts for your Bus Bars, both here and on another forum and can't determine the dimensions of the copper you're using. The thickness really.
Thanks!!
Allen
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MtnDon
Member
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# Posted: 21 Mar 2012 10:19am
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3/16 x 3/4 solid copper
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TomChum
Member
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# Posted: 29 May 2012 03:03pm
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Dug a trench and buried my 2/0 cables in 1 1/2 conduit. I chose 1 1/2 because of the tighter bend of the 'elbow'. It would have been MUCH better to use 2" conduit, and then 'size down' to still use 1 1/2" elbows. It was a tough job getting the conduit under four big tree roots!
I ran a 12 ga romex out to the panel too. Not sure what I might use it for, maybe for the generator (93 feet) from the cabin. I was tempted to put a Cat5 cable in there too, but ran out of time to get the cable before leaving for the cabin.
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sparky1
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# Posted: 2 Jun 2012 12:51pm
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Just wondering:?
I have a 8D battery in the basement under the porch for my 12 volt lights-I laid a piece Plywood on top-keep battery cleaner,dust etc;
wow the Gassing / acid splash is eating the plywood. you might want to watch what Happens to the floor of your cabin where the battery's are.Maybe rack it out Tack some plastic over the battery's
sparky1 in s.Va.
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TomChum
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# Posted: 25 Jan 2013 10:10am
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I plan to put steel above the batteries so gassing can't get to my wood. One problem I have is; snow piled up, then turned to ice, and I can't slide the drawer out far enough to water, or observe the batteries at the back of the drawer.
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MtnDon
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# Posted: 25 Jan 2013 12:34pm
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Try to get something plastic, fiberglass, lexan, other than steel as it corrodes. So will aluminum.
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