GoldenMotor.com Forum
General Category => General Discussions => Topic started by: Marsbar on January 17, 2014, 07:23:06 PM
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Had some troubles with range on my batteries. Before I used 4x12V 12Ah SLA (Heavy!)
After that I bought a 48V 10Ah lithium battery on e-bay, built in BMS. Charger is only 1.6A, so it takes approx. 6.5hrs to recharge it.
Problems: Battery seems to be fading even after 50-100 charges. Also, when cold (say 0 degrees Celsius) shuts down and have to be re-started (Power on and off motor)
Now problem is, if going to town (10km hills/wind) I seem to use up the entire battery. Have adjusted the motor to 48V 10A.
So I need to charge it in town. But shopping stop is often only 1hrs, not 6.5hrs it need to charge.
Also, I suspect the battery drains itself if left for a week unused.
Well, seller has evaporated from e-bay so I thought of making one or two extra battery packs to extend the range.
So I found this:
http://www.ebay.com/itm/15x-5000mAh-3-7V-18650-Li-ion-LED-Flash-Lighting-Torch-Rechargeable-Battery-Pack-/300919589718?pt=US_Rechargeable_Batteries&hash=item4610348b56
Only USD 27!
Also I need this:
http://www.ebay.com/itm/BMS-for-48V-13-cells-Li-Ion-Battery-Pack-50A-10A-limit-With-Balance-Function-/151034601971?pt=US_Rechargeable_Batteries&hash=item232a5d21f3
Thinking of having two cells in parallel, this making a 48V 10Ah pack. Using a dremel to scratch surface and a 100W high temperature soldering iron to solder on wires by being quick.
Price will then be:
2x27+56=USD110. Shipping: 20USD.
Now there appear to be a problem shipping 48B batteries, but I don't think this applies to single cells.
I plan to use my existing charger 56V 1.6A og my SLA charger that also gives out 56V. I am not sure if I can use an SLA charger instead of lithium charger, but voltage out from both chargers are exactly 56V, and I assume the BMS cut's off charing current at the end.
Are these cells to good to be true? Instead of buying a pre-made battery pack I am determined to make my own instead, and when the cells are used I could re-use the charger and BMS.
I plan on having two or 3 battery packages, each with it's own BMS and charger. Reson for this is to split things up, if something fails I have backup!
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you may want to find out the discharge rate of those ebay batteries the 'C' rating. As they may not give out the power you will need.
I build battery packs with 18650 li-ion cells and I do not use a balancing board for them. I just charged them individually with a charger that takes 6 cells until they are full. I leave them for a week and then measure the voltage of each one to see if they have dropped voltage. ones which have I do not use, with the others I build up in lines of series (13cells + to - ) to get 54v fully charged. and then I parallel them together at each end of the line + to + and - to - .
Once done I add a fuse holder with a 40 amp fuse in it. hen use about 3 rolls of insulating tape to wrap around it all to keep it tight and to insulate. I put wire connecting plastic screw block to put all the positive wires in one side of the block and the negative to the other side. then have the fuse holder coming out of the other side of the block and put an andersons 50amp connector on the end.
I use thick house hold grey cable and strip it to get the earth copper wire out of it and cut it into one inch pieces which I use for wiring the the cells pos to neg when putting them in series.
I wish I had some pictures at hand but I have not got around to it, to make a tutorial. All you need is a good soldering iron.
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I found this...... The cells are already in pairs when I start.
(http://www.arhservices.co.uk/apaclark/8cd8d2ad955fb3885d15e981c6902332_zpsf508504e.jpg)
(http://www.arhservices.co.uk/apaclark/493379248bfeae1286b7311da6c25f20_zps304478c3.jpg)
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In order to use more battery packs, and combine lithium and my old SLA
(I filled water in them, maybe they work better now?) I am thinking of using a diode
bridge as shown.
These diodes (two in one package) will allow me to connect two battery packs at once. The diodes ensures I can use two different packs, and they will not see each other, only deliver current.
(The diode shown need a good heat sink, since it will get hot!)
So I can use SLA and lithium together. The SLA will give good acceleration, and the lithium will give a good run...
But I want to get rid of the SLA all together. So back to lithium!
If I skip the BMS, how do I treat my battery pack? My suggestion is below:
1)Max discharge: I assume you simply add a glass fuse 10A in series with the batteries, to ensure
short circuit protection and fire
2)Under voltage: I assume you know your ride length or simply look at the voltage. I could add a
voltmeter and stop using the pack when the voltage is too low.
3)Charging: Now this is difficult. Could I connect a 56V charger and an Ampere meter.
So, when I start charging, say it draw 1.5A. After the current drops to say 300mA, it means the battery are full and I have to manually take the charger off. Could this work?
Now, with the above, do you think I can go ahead without a BMS?
It would greatly simplify my design and cost not using a BMS... I could simply add one later ::)
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i really have no idea at all about using differing battery chemistries together.
I use a Li-ion charger that came with a golden motor kit for a 48v pack, rated at 2amp out put. I put a watt meter between the battery and charger and switch it off when the amp input drops to 0.50. The charger will turn off on its own, but leaving the 0.50 space is probably good for not overly charging. I do a 10 mile round trip with an 8 to 9 AH pack.
As you say you could add a watt meter between the battery and controller to watch out for under charging. I use cheap watt meters from China as off ebay.
i will try and get a photo up when the app on my phone decides finishing loading up. >:(
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I use anderson 50 amp connectors on the watt meter as seen on the charger adaptor that is also pictured.
(http://www.arhservices.co.uk/apaclark/Mobile%20Uploads/2014-01/30D75B41-C794-42CD-94D6-C8A862FADB25_zps0wjbgz8w.jpg) (http://s39.photobucket.com/user/apaclark/media/Mobile%20Uploads/2014-01/30D75B41-C794-42CD-94D6-C8A862FADB25_zps0wjbgz8w.jpg.html)
(http://www.arhservices.co.uk/apaclark/Mobile%20Uploads/2014-01/8C099CA3-A76C-4C1E-845F-8D941D3EFF10_zpslgwvzaba.jpg) (http://s39.photobucket.com/user/apaclark/media/Mobile%20Uploads/2014-01/8C099CA3-A76C-4C1E-845F-8D941D3EFF10_zpslgwvzaba.jpg.html)
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The cells I found on e-bay seem to be FAKE, some report capacity is often 1/10! How do I know the cells really have 5000mAh capacity? If it's too good to be true it often is... ???
I need a verified source, no use buying heaps of cells of poor quality.
Anybody that has bought cells from e-bay that matched the capacity? Would love to hear from you.
I am also willing to cut open PC batteries, since these probably are of good quality as an owner of an laptop would reveal the capacity instantly after some charge and discharge uses.
I bought a new battery for my computer, so that is verified. Contains 6 cells each 2200 real mAH.
Each cell would then cost me $6, but at least I know what I get :P I have tested the cells in my laptop 100 times so I know they are the real deal ;D
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yes, lap top batteries are what I use. that's a good plan. you would need 54 cells to make a 48v 8.8ah pack which would be easy to make. another 13 in parallel would get you up to 11ah. They are usually soldered together in pairs. I find that charging them like this is fine to get them up to full charge on a 18650 cell battery charger. I bought one off ebay that charges 6 cells at a time or 3 pairs as I do. It takes a little while to get them all charged. Then I wait a week to see if any have dropped voltage before wiring them together. :) it takes about 2.5 hours to charge the pack in bulk after I have done 8 - 9 miles.
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Meanwhile, worked on my diode bridge. I now have 10Ah lithium in, and 12Ah SLA in.
Worked sweet. Total capacity is now 48V 22Ah. Should get me to town and back without recharging ;D
Had a small test drive, seemed to work well.
Now! Problem is that I am back where I started, SLA is simply too heavy for a bicycle wheel and a small bump could break my wheel or spokes... :P
Also, today I read the following by a professor in battery chemistry:
http://www.tu.no/it/2014/01/19/slik-far-du-maksimalt-ut-av-mobil-batteriet
"If you keep a lithium battery between 40 and 60% charged, the life span on the battery will increase from 300 cycles to 20 and up to 25 times. As long as small changes in lithium going back and forth it will not stress the grid structure the same way.
Many laptop producers offers 100% or 80% discharge due to this".
Wish I had known this before, I should have two lithium packs at 2x10Ah and in a diode bridge, and never use more than 50% in each battery pack.
The battery would then last 6000 (!) charges according to that professor. So the most economical thing to do is to ensure you have enough capacity and only use half of it before charging, also keeping discharge current as low as possible.
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well I am impressed with you solution :D
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"If you keep a lithium battery between 40 and 60% charged, the life span on the battery will increase from 300 cycles to 20 and up to 25 times."
If you only charge it to 60% of its capacity and never discharge it below 40% of its capacity you will only have a usable capacity of just 20% of the battery's stated capacity.
So, if your trip requires 10Ah of energy, you would need to have a 50Ah pack for this to work! ::)
You may have to sacrifice your battery's theoretical extended life expectancy for more practical reasons (size and weight).
Alan
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Well what the article says is to never drain batteries more than 80 percent, preferably 60 to 40 percent to make them last really long. Would be interesting to see if a battery could get 2000 cycles instead of 500 by this way. That would half the battery cost! A bit more expensive at first, also extra weight, but maybee you get the money back in the long run if you use the bike every day.
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when using li-ion packs I try not to let the voltage when rested for a couple of minutes to go below 48v, as 54v is full charge. while using the battery I have a cut off of 42v to be safe. A programmable controller or a cycle analyst helps to do this. As said above, practicality and weight are most important. Keep the li-ion pack topped up after every trip.
If the pack pack does go down to 47v rested, and 41v when at full pull, then that is up to you, but you will be stressing the cells more.
48 / 13 = 3.7
42 / 13 = 3.2
47 / 13 = 3.6
41 / 13 = 3.15
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Nice looking batteries Andrew :) lol
Marsbar, are you in the south of england ?...i got a few 18650 cells kicking around that I don't use at the mo.....
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yup, I am sure you recognise the cells. I have not mastered the artistic triangle packs as good as yours, but I am now fully educated (by you) to build my own packs. I tear down your packs and charge the cells that are still good to build my own. I owe you everything ;D
You need to see my lipo set-up... hard case/shell back pack with springy coiled cable going from back pack to under the seat to andersons connector. A bit William Heath Robinson but with room in the coiled cable to stretch for a fall off road. I must admit Paul, you are missing out :)
But then again, I had a really bad slam off one of my bikes going to work two weeks ago on black ice right outside my school. I had a dead leg for a week where I fell on my thigh with keys in my pocket doing 20mph, rippped trousers and jacket and a bruised ego, knees,elbow and thigh. I have since developed what I think is a cracked rib which is getting worse as the days roll on. I was picked up off the floor by two young school girls that treated me like an old man and helped me onto my feet and even picked my bike up for me. As you can imagine I was the talk of the school and I got absolutely no sympathy from the kids I teach who all thought it was hilarious >:(
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aww dude, hope you are ok soon...get some schwalbe ice spikers...ice is not to be sniffed at,,,failing that get some bomber shorts :)
Times have changed since we last spoke, and Im back in the ebike business due to circumstance ( and yes I had to go and buy again what I sold you lol :) )
im working on a stainless steel kickplate triangle battery pack bolted to the frame...heat dissipation, centre of gravity, should work a treat, and look almost as sexy as I do
The problem I had with backpacks is that my front wheel never wanted to stay on the ground on high power take off's...One M4 roundabout looking like evil knevil finished that Idea for me
Hope the family is keeping well :)
p.p.s got a few more 18650 cells that im not using .....if ya want them
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well, its good to have you back on board. :D
I am not sure how long the back pack thing will be used as I too am working upon a triangular frame solution for my suspension frame 8) I have so far made two press moulds from PVC foamex plastic that will be bolted together to the bike frame. The container will cover of the top frame bar as well as the inner triangle allowing more room for cells. Thanks so far to the DT department in school and the diner ladies who let me use their big oven to heat the plastic sheet before ipressed it over the wood moulds I made. that's as far as I have got at present. Next step is fitment, i.e cutting, sealing and making a side flap for access. Big plans with lots of problems ahead of me! ::)
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Good luck with that Andrew. Why not put up step by step pictures with an explanation of what you are doing.
That could be a hit. I would follow that. It might encourage others.
Gregor.
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as usual, it is finding the time. I am meaning to take some photos soon of both battery carrier solutions I have been working on.. i.e the plastic mould and the back pack solution. Both are for my full suspension mtb for off-road use only. The commuter bike has a frame mounted bag for the controller and cells.
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What volts are you going to be putting out of that pack?
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i stick to 54v as this is enough for me. I have mpacks of lipo cells wired together, each is 54v and 3ah, I have seven in total which can be paralleled together to make upto 21ah. I use the lipo just for my full suspension bike with a PIE mk2 for off roading. the controller and cycle analyst will be set to 35amp max, so will pull 2000 watts. I have had a lot of help along the way from Forum member DirtyGinge and Bikemad.
I was exactly where you are now 3 years ago. I went through various hick-ups and cock-ups from Golden motor but overcame them all and have had a steep learning curve.
I now do lots of soldering, tinkering, bodging, modifying.
Build li-ion packs
Build wheels
and have built over six different bikes/kits/variations along the way.
I did not know the difference between volts and amps when I started never mind anything else related to ebikes. ;)
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One question. My controller was set at 30amps continuous and 70 max. Peddle assist was at low, I don't use it anyway. RPM set at 90%, voltage36V, speed scale 100% and the regen at 50%. All I have did with the software was disable the reverse and turn the regen down to 1%. Question is, does that sound ok? I have the 48V10AH lipo battery.
Cheers
Gregor.
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i think you have a Lifepo4 battery a bit different to Lipo but still a very good discharging chemistry. 70 amp max sounds very high to me, but what the GM controller does and says are two different things.
If you did pull the max 70amps at 42v on full charge that would equal nearly 3000 watts. Your motor inner parts and wires would melt at that wattage :D. If the controller really lets out 30amps then that is a good amount for your set up. the older controllers were very limited.. i.e 17amps max.
If you connected a watt meter you would probably find a peak of 1200w or there abouts.
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Sorry Andrew, My bad. It is the Lifpo4 that I have. My mistake.
The new controller that Gary Salo sent me was the upgrade.
I have sent Bikemad A.K.A. Alan the exact settings to ask his opinion.
No offence meant to you but he does seem to be a guru.
Gregor :o
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To backtrack a bit. Have you put any pictures of your bikes on here already?
Gregor.
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there are some piccys somewhere of old bike builds.
here are my two ridses at present.....
(http://www.arhservices.co.uk/apaclark/adae08f27cbc052404cc7533e4d8bcec_zpscfeeb37c.jpg) (http://s39.photobucket.com/user/apaclark/media/adae08f27cbc052404cc7533e4d8bcec_zpscfeeb37c.jpg.html)
(http://www.arhservices.co.uk/apaclark/36fb8c24bcde9a049d6fb3d9cdcad4ba_zps5cdcbcc1.jpg) (http://s39.photobucket.com/user/apaclark/media/36fb8c24bcde9a049d6fb3d9cdcad4ba_zps5cdcbcc1.jpg.html)
Two pies......
(http://www.arhservices.co.uk/apaclark/DSCF2006.jpg) (http://s39.photobucket.com/user/apaclark/media/DSCF2006.jpg.html)
two mini motors on this one
(http://www.arhservices.co.uk/apaclark/IMAG0038.jpg) (http://s39.photobucket.com/user/apaclark/media/IMAG0038.jpg.html)
The wife's mini motor
(http://www.arhservices.co.uk/apaclark/IMAG0047.jpg) (http://s39.photobucket.com/user/apaclark/media/IMAG0047.jpg.html)
Another build....
(http://www.arhservices.co.uk/apaclark/IMAG0082.jpg) (http://s39.photobucket.com/user/apaclark/media/IMAG0082.jpg.html)
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Nice rides. Where do you put your battery on your fully sussed bike and how do you stop your controller getting a soaking?
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Nice rides. Where do you put your battery on your fully sussed bike and how do you stop your controller getting a soaking?
I am experimenting at the moment with the controller placement and battery pack. I have done my best to make the controller waterproof so it can be mounted externally, which is probably a good idea due to the power going through it.
I do have a small frame bag that the controller can go in within the frame. A battery wire comes from the controller in the bag and goes up the seat post and I connect to the batteries on a back pack with a coiled cable under the seat. This still keeps everything back heavy, hence trying to make a PVC plastic moulded frame container.
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well im preparing on making an aluminium triangle for the bike frame, housing the lipo, and potentially the controller innards as well. That way I can heat sink the fets direct to the outer casing... got a wooden one built at the mo, and the low centre of gravity really helps the stability......
As for the pie settings, I found that 20 amps with peak of 60 was plenty for commuting, but that wasn't with a GM controller..
Also plan to hard wire the controller soon, getting rid of all the finicky plastic connections and go for direct solder, just cant decide which controller to stick on it, sensorless or sensored :)
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You know sensorless makes more sense.... if that makes sense! :o
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yea, they aren't as snappy as a sensored, but I guess if im going to hardwire, wont want to be undoing it too often :)
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Here's my plastic press moulding attempt so far....
(http://www.arhservices.co.uk/apaclark/Mobile%20Uploads/02649B9D-9428-40D1-A122-FB92B53556B4_zpsrg9giulu.jpg)
(http://www.arhservices.co.uk/apaclark/Mobile%20Uploads/BFDA1A27-9C19-469F-AC9E-0E2CAEE80CFB_zpsxzm9yeoz.jpg)
(http://www.arhservices.co.uk/apaclark/Mobile%20Uploads/711BEA6B-0E4E-43D8-9A2D-1928D4822641_zpspo8rxbwm.jpg)
(http://www.arhservices.co.uk/apaclark/Mobile%20Uploads/F1B965AA-1B83-42F6-8C23-5A91C6283FD9_zpsjsnoad83.jpg)
There is still plenty to work out.... Sealing, opening and fitting being the main things...lol ;D
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Andrew, that looks very smart indeed, now I'm waiting to see the finished item mounted on the bike. ;)
It looks like you have used plywood for the outer part and laminated MDF for the inner plugs, but why are there two inner plugs?
I was expecting two outer frames that clamped securely together either side of the material being formed and one centre plug which could be pushed into the heated material from either side to create the two halves of your battery box.
Alan
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To create extra space in the frame container to hold 18ah (54v x 6 3ah packs) the container will sit over the top tube frame of the bike as well as inside the frame triangle. I will now have to make semi circle cuts at each end of the moulds so it snuggly fits over the top tube frame.
To do this will be a bit of a pain to get correct as the top tube of the frame is an oval shape.
I will try and get the exact shape by moulding some foamex strips around the top tube to get he exact shape needed before I cut into the ends of the mould, this will be the tricky bit to get right.
I am going to use some neoprene beading around the edge of one of the mould sides and some around the holes I have to make to go around the top tube of the frame. I will then need some kind of fastener, nut and bolt if necessary to bind the two halves together to make it water tight. I would rather use some kind of fastener/clip to secure the two sides together for easier access to the lipo packs for balancing but as you can probably tell I am making it all up as I progress ;D
I have not found a suitable clip yet. I need something like a jar clip fastener like used to seal large kitchen jars. If you have any ideas of what I can use please let me know. I really need to get to a fastners producer, I believe there is a place in Cardiff I can go to with my problem.
This is a long term project so don't expect any finished results soon. I really am making it up as I progress. It has not really cost me anything but time so far as I used spare pieces of mdf and got the foamex from school as an experimental project.
I wish I could add some diagrams but don't have the means to do that on my ipad.
I am a bodger rather than an engineer but I love problem solving in situations like this.
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Andrew, that looks very smart indeed, now I'm waiting to see the finished item mounted on the bike. ;)
It looks like you have used plywood for the outer part and laminated MDF for the inner plugs, but why are there two inner plugs
Alan
I made one big plug and then cut it in half. The width of the mould when put together is around 81mm which is the size of the lipo bricks I am using, so I get a tight fit to stop the packs jiggling around. No doubt foam and may be shelves will be needed to pack in as well. If I made one deep mould rather than two the plastic would have to be over stretched, dothing both sides at the same time would have been impossible. I literally pressed the outer frame over the plug. I had to do several tries as I had to estimate how much gap to leave around the outer frame. 10-12mm did it. The foamex has a memory so when reheated it goes back to its original state i.e a flat panel. Great stuff.
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The foamex has a memory so when reheated it goes back to its original state i.e a flat panel.
I suggest you make sure that you don't leave it out in the sun or your battery pack will end up shrink wrapped. ;D
You need to be vary careful that the materials you select are suitable for the expected temperatures otherwise this can happen:
(http://www.toxel.com/wp-content/uploads/2012/07/meltedvan05.jpg)
(http://www.toxel.com/wp-content/uploads/2008/10/meltedsigns2.jpg)
Especially with our incredibly hot British climate! ::)
Alan
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Haaaah, you have a good point, The temperature used to soften the foamex is around 200 degrees C. I first tried using a heat gun to see if I could make it soften and it took quite a while just to get a corner to soften. I used an industrial oven to do the job as a normal home oven was not big enough for the sheets I was using.
I may try and use hand tightened screw on knobs (male to female)to keep the two halves closed with a hinge on the lower edge which you can see masking taped in the photo.
http://www.ebay.co.uk/itm/291051325822?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648 (http://www.ebay.co.uk/itm/291051325822?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648)
http://www.ebay.co.uk/itm/191037026008?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648 (http://www.ebay.co.uk/itm/191037026008?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648)
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Dirty Ginge, still have some cells? PM me...
Type?
unused?
how many?
price?
quality?
live in norway postage is cheap and fast from you, no tax on gift...
had to lower my controller to 16A to save battery meanwhile
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hi bud
apologies, Norway is just way too far for the weight.......they do add up kilos really quick
I was thinking you were in UK for free collection :(
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Nah! We are not sending SLA trough the mail here... for me postage from UK is dirt cheap, same price as internal in Norway...
You know Norway is expensive, 99NOK (£10 for a 0,6litre beer!)
Still, let me know what you have