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Forum Index : Electronics : Used batteries - your experience please
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Bernie the Bolt Regular Member  Joined: 26/10/2006 Location: United KingdomPosts: 45 |
Hi All, I am starting to get together bits for my first windmill (using a 100 series 2.2 meter diameter blades) I am hoping to source secondhand batteries ( I may build a desulphator) and as I live a couple hours drive from Clermont Ferrand in France (a large industrial & manufacturing city) I was hoping to find a Firm dealing in Fork lifts from whom I could obtain used Fork lift batteries. My question is : Does anyone have experience on used Fork lift batteries ? What amperage / volts are they likely to be ? Is a battery unable to operate for an eight hour shift on the shop floor still of use to me ? What size of battery banks do you guys have ? I guess enough questions for one post. Bernie the Bolt I'd rather be sailing! |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5029 |
I would get in contact with a firm that supplies or repairs forklifts, and see if you can make a deal to take away the used batteries in exchange for beer ( or wine may be a better trading tool in France ). I think the batteries in forklifts are changed when they get a little low on power, or they are out of warrenty. You would find most of them would give you a couple years of good service. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Bernie the Bolt Regular Member Joined: 26/10/2006 Location: United KingdomPosts: 45 |
Good idea Gizmo, Can you glance over my intial calcs please? You will see I have made a lot of assumptions about wind availability etc. What would maximum power (watts) generated be ? 600w (from thebackshed forum) What then would the maximum current (I in amps) be ? (assuming system voltage 12v) So P = V x I So P = I/ V So 600 /12 = 50 amps What therefore would a suitable battery bank capacity be? Assumptions : At this site (Limousin in France)windy days are 3 out of7 Assuming 50 % output for those 3 days : 3 days x 24 hours = 72 hours 72 x 50/2 = 1800 amps for seven days or an average of 257 amps per day Usage : 6 x 17w compact FL for 6 hours per day : 2 x halogen 50w for 3 hours per day 6 x 17 x 6 = 612 w 2 x 50 x 3 = 300 w 912 w + 10% loss 91 w (due to inverter) 1003 w total Expressed as current : = 83.6 amphours er day (P/V =I) Assuming 3 days without wind 83.6 x 3 = 250.8 amp hours usable Battery capacity required. Assume battery efficiency 90 % so 250.8 /90 x 100 = 278.66 amphours If target maximum discharge is 20% of battery total capacity , battery bank needs to be 278.66/20 x 100 = 1393 amphours ! At average output the wind turbine would recharge this in one day (less amps used on that day) Or at 24v 700 amphours ( but to get a 24v bank would still need the same capacity of 12v cells – so 24v gives no saving on battery bank) Improvements to efficiency / capacity of system : 1. add a PV panel – say 50 watt say 8 hours per day for 4 days out of seven = 50x8x4 = 1600 / 7 for average per day = 228 watts so for 12v = 19 amps per day average input Bernie the Bolt I'd rather be sailing! |
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| domwild Guru  Joined: 16/12/2005 Location: AustraliaPosts: 873 |
Bernie, I have a 36V UPS and some forklifts use 36V batteries. So I went to a battery shop specializing in forklift batteries and, lo and behold, those batteries are as big as Texas and as heavy as a ...... (include hated nationality) mother in-law (bon maire). Forget hunting for one of those, use three 12V BUT there is the problem of getting three old one which are equally shot!! Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up. Winston Churchill |
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| Feral Newbie  Joined: 03/12/2006 Location: AustraliaPosts: 39 |
Bernie, You will find that most forklift batteries are made up 2 volt cells and are designed to be linked together to make up the required voltage. That is how all that I have seen in Australia are and I would expect that Europe is much the same. A past friend of mine in Cairns used to manufacture batteries of the automotive and truck type in the hard black rubber cases and the forklift batteries were purchased complete one cell at a time in thick plastic case and installed in large metal case and then joined together with poored lead liks joining up the terminals. I have recently assisted a friend of mine in pulling apart large 12v battery bank to retrieve the good 2v cells. Usually only one cell will bring the voltage of the bank down and when this happens most go to the recycle depo (dump) because who would know that one cell could be at fault. You may be lucky finding enough second cells to make a bank in this way. It has been done before and they are perfect for remote area power supply. As for size the bigger the better because the deeper you discharge them the shorter life they will have. If using second hand batteries with some life (lead) left in them dont use it up in the first coulple of months get as many as you can and keep them fully charged and dont discharge to deep. Check voltage on each individual cell and if around 2v they should still charge up. Anything from 2v down to 1.5v is a bit dodgy. Normally one of the cells on one end of the bank is the faulty one, not sure if its the pos or neg that goes first. |
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Gill Senior Member  Joined: 11/11/2006 Location: AustraliaPosts: 669 |
another possible source of Deep Cycle batteries is your local Golf Club if it runs a fleet of golf buggies, or another is Motor Home hire companies. Good luck. was working fine... til the smoke got out. Cheers Gill _Cairns, FNQ |
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| Bernie the Bolt Regular Member Joined: 26/10/2006 Location: United KingdomPosts: 45 |
An update to this thread : Ok so I know it's been a while, but been busy restoring my old farmhouse. Just been to get the Camper van (Motor home) checked at the dealer and happened to ask if they had any old leasure batteries, and was shown a pallet out the back with 5 on ! and as a customer they gave them to me free gratis ! They range from 80 to 125 amphours and are all described as leisure batteries on their labelling, except one a bosch which may just be an starter/auto but is 125amp The most hopefull is a yellow 120 amp (branded FAM) which registers 12.40v but was very low on elytrolyte. On inspecting the plates from the top this one shows no sign of sulphation,but after putting about 3/4 litre of deionised h2o in it some cells are still low. the voltage then dropped to 12.2 .I will get some more water tomorrow and try charging it. The other batteries voltages range from 11.9 to 8.0v - Bernie the Bolt I'd rather be sailing! |
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| domwild Guru Joined: 16/12/2005 Location: AustraliaPosts: 873 |
Bernie, From memory this forum and Fieldlines informed me any battery lower than 10.5 V may not be OK. As mentioned before, golf clubs, and also gofer companies. Have been informed that once a gofer is traded the old batteries are removed and new ones put in and the gofer advertised again for sale. Electric wheelchairs. Any places with UPSs will have SLAs but watch it, an SLA is charged lower, e.g., 14.2 max instead of up to 14.8 for car batteries. Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up. Winston Churchill |
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Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1211 |
Hi Bernie, Mate I've had some good luck with sla batteries. Around 4 years ago I found 30 off 6 volt 105AH sla's at a scrap yard, I took along my dmm and found every battery to be above 6.3 volts so after some haggling I got the lot for $240. These batteries are still going strong today and are my main batterybank in the shed. Around 2-1/2 years ago I got onto 24 off 2 volt 275 sla's that had always been on float and again after haggling I got them for $400. these ones are my backup bank in the shed and when I hooked the 3kw inverter up to them and used my bridgeport mill for a 6 hour stretch they only dropped about 1.5 volts to 25.5 volts. So the moral here is look around and haggle  I'm sure you'll find a decent bank of batteries if you look hard enough.
Cheers Bryan  |
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| greendreamin Newbie Joined: 02/02/2008 Location: AustraliaPosts: 20 |
ive picked up a few over the last few years, all 6v 220ah wet batterys, all of them out of flashing arrow boards and traffic lights (when you park solar powered traffic lights under trees they dont last for more than a few days...) and others with charging faults i got onto them quickly and had them charging flat out for 5 days and they are still good 
Stu |
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| Bernie the Bolt Regular Member Joined: 26/10/2006 Location: United KingdomPosts: 45 |
Good advice guys, I will keep my eyes open whilst building the rotor. Meanwhile I will try a desulphator on some of these ex Motor home jobs, at least they will give me something to hook the F&P upto ! Bernie the Bolt I'd rather be sailing! |
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| Bernie the Bolt Regular Member Joined: 26/10/2006 Location: United KingdomPosts: 45 |
Update on used batteries. I had to dump 4 of the ex motor home batts but the yellow one I mentioned has recovered well with 3 months treatment hooked up to desulphator. It now measures 12.65 v after being left of charge for a week. I am now in the course of testing its capacity by hooking up a 600w inverter to it with a 100w light bulb. The light bulb is plugged onto the inverter via a rotary 24hr timer with all "off" pins removed so I can check on time elapsed. My digital multimeter shows the voltage dropped to 12.2 volt when this rig was connected, the inverter manual states low voltage cut off at about 10.5v, so do you suggest waiting for that to happen, wait 2 hours then checking battery voltage ? Or is 10.5v overkill (literally) Perhaps I could open the inverter and wire couple of diodes to the sensing circuit to raise the cut off voltage. Bernie the Bolt I'd rather be sailing! |
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