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Forum Index : Other Stuff : Battery Rescue?
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| dwyer Guru  Joined: 19/09/2005 Location: AustraliaPosts: 574 |
hi Can anybody clarify if we can make our own supercaps as I believe they are all rapped in aluminum foil and glad wrap and rolled up and put in a plastic tube it sounds like it easy to way so i was wondering if they would work after looking You Tube few years back 
Cheers Dwyer |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Ian Good question. To get the high capacitance, you need a large plate surface area, and a small gap between the plates. Modern super caps have a gap thats only a few atoms thick. I suspect if you made a 1 farad capacitor with aluminium foil and glad wrap, it would be the size of a house. Will see if I can find the formula to work it out. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Found some basic forumla, just for fun. http://www.sentex.ca/~mec1995/circ/hv/hvcap/hvcap.html A capacitor made from two sheets of aluminium 1 meter square, with a 0.1mm sheet of polystyrene between them, will have a capacitance of approx 22nF. To make a 1 farad cap, your sheets of aluminium would need to be 17857142m2, or about 17km square 
Commercial electrolytic caps increase the surface area of the plates with porous/pitted surfaces, and an electrolyte. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Glenn A very good article and well worth the read for anyone in the forum. Many years ago I made roll up caps as described here using alm foil kitchen variety and microwave proof plastic film, I found it better than the normal glad wrap, using big rolls designed for catering use, not a lot of capacity but when charged to 500 volts they really packed a punch. All the best Bob Foolin Around |
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yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Hi Bob, My thoughts are that the best quality NiFe and LFP cells are very close to the same value for dollar and they are both 35%-40% better value than the best gel batteries. I have been collating battery stats on a spreadsheet for quite a while now, using using cents per Kwh as a measure. I work on two figures, one when a battery is run hard and a second conservative cycling number and that gives me a spread. I originally started doing it because I was told that SLA's cost the same per Kwh no matter how deeply they are cycled and I didn't believe it was true. I see that ironcore have a medium and short discharge battery in the works, that would go some way to fixing the voltage slump problem. I'm confused, no wait... maybe I'm not... |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi All Chemical rescue and a few further links for those who would like to try ALUM conversion https://www.youtube.com/watch?v=Supe1a3LW2U This guy seems to have a bit of luck with this method, but remember that it would rely on the battery being mechanically sound to start with. All the best Bob Foolin Around |
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isaiah Guru Joined: 25/12/2009 Location: United StatesPosts: 303 |
Bob Yes we have watched many video's on that and tried it on several battery's we were trying to reclaim with out much luck. The voltage per cell is less also with Alum in it. The alum battery's may be OK to run some led lights or some other lo draw item but probably wont start the car. At this time we are trying just to keep the good battery's in good shape. I have to get one ready for the winter plow truck that the plow lift is electric and the motor lights and yes the heater all draw and a electric fuel pump and it runs at slow speeds so it is rough on the battery. I may put a smaller pulley on the alternator if I have the time and weather. We do have pretty much got Bub's solar array up now he needs to finish the wiring Isaiah URL=http://www.motherearthnews.com/Renewable-Energy/1973-11- 01/The-Plowboy-Interview.aspx>The Plowboy Interview[/URL> |
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| gww1 Regular Member  Joined: 14/06/2013 Location: United StatesPosts: 63 |
yahoo What do you think now. gww |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
gww, I dont have a lot of good data on sealed lead acid batteries yet. there is a couple of reasons 1. most people have no clue how much power they are using 2. quite a few of the batteries that had stopped working were dry inside when I cut them open, so I am guessing that they had been venting while charging for some reason. I have also discarded stats from what I call underused batteries, " little ol lady driven to church " kinda thing. those batteries tend to die of old age, not use. At this stage 250-540 cycles is looking like 20%-60% more expensive to run than 800-1200+ cycles for SLA. It also looks like 20% more expensive per Kw from deeper cycling is as good as it gets for any battery chemistry I haven't found any that stay at the same cost, most are more like 30%. I'm confused, no wait... maybe I'm not... |
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| gww1 Regular Member Joined: 14/06/2013 Location: United StatesPosts: 63 |
So, unless I can't read english (which is possible) it does cost a bit more per kwh if deep cycling. Up to 30%. Thanks gww |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi GWW1 Deep cycling is usually defined as taking more than 60 percent out of the total AH rating of the battery over a 10 hour period. A battery that is taken to 80 percent or more of its AH rating on a regular basis has its life shortened by a large margin depending on design and construction from something like 1800 cycles to 300 cycles, so in effect the FLA battery has only one third of its rated AH capacity if you want to have long life from the battery. This dramatic reduction in life cycles reflects in high operating costs, because it could mean a reduction in battery life span from a potential of 15 year back to 3 years assuming a good quality battery to start with, automotive batteries are much more fragile than deep cycle batteries and could have their lifespan reduced to less than 12 months. To get a long life out of your FLA or other types of Lead based batteries it is better to limit discharge on a regular basis to 25 percent. On the other hand NIFE cells and LIPO cells will still have a good life span to 80+ percent discharge, so a smaller battery bank will do the same job as a larger FLA set. The NIFE cells have a demonstrated life of 30 + years and the LIPO cells have not been time tested yet, but in my experience tend to be less reliable than the NIFE cells with a possible life span of 12 to 15 years on a solar installation. Each type of cell has advantages and disadvantages irrespective of the cost factor, but the main thing is management in all cases, so the real issue is buy the best battery you can afford and it will be cheaper in the longer run. I know people who use two cheap batteries 12 volt 9 plate automotive type cost $130 and have an anderson plug to their car battery for extra capacity using 4 80 watt solar panels and that runs their house lights, water pump engel fridge and radio and TV CB radio and laptop. No inverter all 12 volt application devices. With a desulphator fitted to the batteries they are over 3 years old and still going, so with careful management of power draw it is possible to have a cheap installation perform a useful task. All the best Bob Foolin Around |
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| gww1 Regular Member Joined: 14/06/2013 Location: United StatesPosts: 63 |
bob Thanks for taking the time to reply. I have a 48 volt 800 ah at the 20 hour discharge rate. forktruck battery. I Don't know my loads as of yet but have been running for a little over a year. I would say that I go down to 50% charge quite often. This is my first battery and I am still working on getting and keeping the sgs up. I have read a lot and am always interested. I have heard proponants of 25% discharge and 50% discharge having a differance in life time of battery. Then there is use of the battery and that yes taking 50% kills them quicker but that use (kwh) is the same. I like peoples veiws on this subject. By the way, I don't draw down to 50% cause I like or dislike it, I do it cause I have a self installed system that I put together for the componants to match each other and not to be built around loads. I didn't think I could cover my loads anyway and I will always want more turbines and solar then I have. I do wish I would have bought a bigger battery. I have been watching a good thread on lipo 4 on a different forum but most of it is over my head and pocket book. What hurts in keeping up though. If it comes up a hundred times I might even have a bit of learning sink in. Thanks gww |
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| gww1 Regular Member Joined: 14/06/2013 Location: United StatesPosts: 63 |
PS My wife might just kill me if I only get three years out of my battery. Cheers gww |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi GWW1 I would kill you to if you kill that battery in 3 years, seriously though you have a very good start as a forklift battery is designed for deep cycle and the construction of the battery is very robust. The main thing is to be sure and equalize charge the battery to 64 volts and hold at that for an hour or so a couple of times a week also to fit desulphators one across each 12 volt section of the battery pack, and check each cell voltage with a DMM to be sure there is no lazy cells, good idea to make a log of the voltages in your notebook every month, if you find a lazy cell move it to the positive end of the battery pack. All the best Bob Foolin Around |
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| gww1 Regular Member Joined: 14/06/2013 Location: United StatesPosts: 63 |
Bob I absorb at 61.2 volts and equalize monthly at 63.2. volt. I usually have chargeing or discharging going on so I spot check my laziest cell's sg to keep track of what the state of charge is. No moving around of cells as they have souldered or brazed lead bars connecting them. I didn't mean to steal the thread but like reading this stuff and trying to put it to my own situation. I bought the battery new. and have been working towards raising a couple of cells sg since. Figuring batteries out is a little harder then one would think. I live in fear that I am overcharging and undercharging all at the same time. Either way I found the kilowatt/battery life discussion very interesting. Thanks for your thoughts gww |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi GWW1 It looks like you have your system sorted out well, starting with a new battery like that, you should get 10 - 15 years out of a forklift battery with good management, I would still recommend a set of four desulphators as a safety measure just in case you need to go beyond the 50 - 60 percent level of discharge on occasion. It is permissible to add a balancing amount of acid to a slightly lower SG cell, consult the manufacturer maintenance manual for cell volume and do it slowly after the equalization charge. All the best with your project. Bob Foolin Around |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Isaiah Back to snow plow already that's a worry, smaller pulley may help if the alternator is going below its rated output now. The solar of Bub's is a worry with winter coming on you may be a bit down on sunlight, maybe a bigger wind turbine might help as Your location is windy from memory, last time I was there I nearly got blown away and frozen at the same time. The Alum battery thing is ticking in my head and I have the two batteries from the original battery rescue to play with as they have not responded to my last efforts one has a shorted cell I believe from conductive sludge in the bottom and the other one works but has a fast self discharge rate indicating a sludge buildup on the bottom of the cells making a partial short and hence a faster than usual self discharge. Next week I will empty out the acid and flush and neutralize and try the ALUM trick, don't expect much as such a weak electrolyte will have a lower current per cell area but it may be OK to run the led lights, and it should be longer lasting than acid due to lower corrosives of the electrolyte, anyway it will be an interesting experiment. All the best Bob Foolin Around |
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| isaiah Guru Joined: 25/12/2009 Location: United StatesPosts: 303 |
Bob The last one we tried the bottom was full and I gave it two sessions with water and baking soda then rinsed it with the garden hose til the water started to come out clear. We then did the Alum thing I mixed all I could get dissolved in the water and put it in and started charging. The battery started to come and then went backwards. WE are wondering if there wasn't some soda water trapped somewhere and nutralised the alum. Its still setting there at 4 volts if any one has any idea? Isaiah URL=http://www.motherearthnews.com/Renewable-Energy/1973-11- 01/The-Plowboy-Interview.aspx>The Plowboy Interview[/URL> |
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| gww1 Regular Member Joined: 14/06/2013 Location: United StatesPosts: 63 |
When you guys are emtying the batteries and refilling, does the bare plates being exposed to the air cause more damage? gww |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Hi gww, if the manufacturer says absorp is 61.2 for that model of battery then you are good. Forklift batteries have a tendency to layer the acid if you are too soft on them, they need a bit of gassing to stir the fluid up. Likewise it is good to suck and squirt 3 or 4 hydrometers of acid before you draw one to measure the SG just to stir the top layer up a bit so you dont get a falsely low number. Like Bob says if you have had your batteries from new, so you know the history, and a couple cells have always been a problem it may be possible that the acid concentration has been slightly low right from the start. I have only had to do it a couple of times, adding acid when i re-watered the other cells. It took about 4 fills (9 months)to sneak up on the right SG. some rough calculations that may interest you. a good traction battery should do 1500+ cycles @ 80 discharge. so 49.4 volts X 770 Ah = 38Kw 38 X 0.8 X 1500 = 45,645 Kwh over the forklifts life. add 30% for the gentler discharge of solar use, say 60,000kwh. then pick a number for your nightly use? 15kw perhaps. 60,000/15kw = 4000cycles = 11 years minimum life. like I say, very rough but it should be in the ballpark as a starting point. I'm confused, no wait... maybe I'm not... |
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