Need some advice recovering some batteries
- Thread starter pdarnett
- Start date
Hi pdanrnett,
I'm using an old wheelchair battery, till I figure out a bit more. They knock around my workshop for 12v sources, and are disposable.
The first go was opposing points, today I will double up the battery, beef up the cables, and line up the points parallel as d8veh's excellent link. Later I'll try to set the pressure and timing better.
Cheers, Camerart
I'm using an old wheelchair battery, till I figure out a bit more. They knock around my workshop for 12v sources, and are disposable.
The first go was opposing points, today I will double up the battery, beef up the cables, and line up the points parallel as d8veh's excellent link. Later I'll try to set the pressure and timing better.
Cheers, Camerart
Essentially are you just arc'ing the contacts on the battery (albeit through some leads)?
That's so easy! I've tons of SLA batteries if that's true.
That's so easy! I've tons of SLA batteries if that's true.
Keep an eye on the batteries, they may vent hydrogen if over stressed. Not the best gas to have around with sparks!
I've been randomly walking into laptop repair shops and asking for old batteries for quite a while now
I have only ever twice recovered cells of under 2000mah
The trick is in finding those shops that have contracts with offices. They quite often seem to replace batteries at the drop of hat ( the cynic in me says not always required but it bolster their income and the offices just take their word for it)
Plus side is batteries are rarely very old (ie low mah cells) and lots of them have most or all of capacity
I'd say 70% of cells I pull out are 2200 Samsungs
The best I've had are 2900mah panasonics and quite a few 2500mah LG
Just my experience
Cheers
D
Deleted member 4366
Guest
That's a better strategy. I bought several job-lots from Ebay, which were much older. Most of them were still OK except one lot thathad been tested and marked bad.
Spot weld
>>>http://youtu.be/rzZziUwTRoE>>>>>
Here's a video of today's 10 minute effort. Ignore most of the smoke, it's from the insulation wood below the weld and my connections were simple jump lead to wire on the edge of the table, so varnish from the right.
The metal is part of a spring from a tape measure, 0.015MM thick. The probes have about 1 to 1.5mm contact flat. The timing was wait for smoke! I used two wheelchair batteries in parallel, they read 12.49V before and 12.51V after the weld.
I think what should happen is the contacts should be in even contact with the job, at about 1/2 kg pressure, then have an on/off switched timer, that can be altered to a % of a second, adjusted for best result, perhaps 1/4 sec. I will use a PIC chip and Mosfet.
Hope it helps.
Cheers Camerart.
>>>http://youtu.be/rzZziUwTRoE>>>>>
Here's a video of today's 10 minute effort. Ignore most of the smoke, it's from the insulation wood below the weld and my connections were simple jump lead to wire on the edge of the table, so varnish from the right.
The metal is part of a spring from a tape measure, 0.015MM thick. The probes have about 1 to 1.5mm contact flat. The timing was wait for smoke! I used two wheelchair batteries in parallel, they read 12.49V before and 12.51V after the weld.
I think what should happen is the contacts should be in even contact with the job, at about 1/2 kg pressure, then have an on/off switched timer, that can be altered to a % of a second, adjusted for best result, perhaps 1/4 sec. I will use a PIC chip and Mosfet.
Hope it helps.
Cheers Camerart.
Wow, lots of smoke, not sure if I'd be happy putting that amount of heat on a battery contact!
Found these today, looks interesting, 18650 holder with a built in BMS!
http://www.ebay.com/itm/2-x-1S4P-3-7V-18650-Holder-Case-Battery-w-Li-ion-PCM-Protection-Circuit-Module-/400639920000?pt=LH_DefaultDomain_0&hash=item5d48000780
Found these today, looks interesting, 18650 holder with a built in BMS!
http://www.ebay.com/itm/2-x-1S4P-3-7V-18650-Holder-Case-Battery-w-Li-ion-PCM-Protection-Circuit-Module-/400639920000?pt=LH_DefaultDomain_0&hash=item5d48000780
Here's some a bit cheaper: http://www.ebay.com/itm/2x-Battery-Holder-Case-for-3-7V-Li-ion-18650-17670-battery-1S4P-w-PCM-Inside-/321135540793?pt=US_MP3_Player_Cases_Covers_Skins&hash=item4ac52b7a39
You might be able to buy a load and agree a better price/
I've been looking at cells/batteries, and with no experience, it's difficult to work out the difference in value between second hand and new. I've seen some new ones at just over £1 each. Obviously it depends on the actual capacity, lifespan and rating of cells. I just wondered if it might be better in the long run to use new? Also the supplier!
You might be able to buy a load and agree a better price/
I've been looking at cells/batteries, and with no experience, it's difficult to work out the difference in value between second hand and new. I've seen some new ones at just over £1 each. Obviously it depends on the actual capacity, lifespan and rating of cells. I just wondered if it might be better in the long run to use new? Also the supplier!
D
Deleted member 4366
Guest
D
Deleted member 4366
Guest
Don't buy cheap 18650s. Peel off the outer covering and you'll find a different designation underneath, and the end-caps are false. Underneath are the originals with weld marks on.
It's best to buy from proper registered suppliers.
I did see the wood burning, I'd be worried about that intensity of heat on a battery terminal for any length of time. It look like it had melted through the strip as well. Wonder if there's a way of reducing the current or maybe just the pressure or time?
The protected battery holder only a lot cheaper and they drop as you buy more, price includes shipping.
http://dx.com/p/diy-2p2s-7-4v-4-x-18650-battery-charging-case-black-285182#.Utca8vQW294
http://dx.com/p/diy-2p2s-7-4v-4-x-18650-battery-charging-case-black-285182#.Utca8vQW294
The video I posted was only a 10 minute to make, experiment to see if there was enough power in a couple of wheelchair batteries, and as you can see there is. Forget about the smoke!!
With most welding what's needed is correct penetration, the welder gauges the heat and time for the best weld. The holes show there is either too much heat or for too long, so as it's better to get in and out as quick as possible, this equals more heat for less time, and heats the object (cell) as little as possible so with my demonstration all that need doing is to get the timing right. This will be done as I said with the correct pressure before the electric, then time the burst to suit, with electronics.
Hope this helps, (please don't hold me responsible, for my lack of accuracy).
Cheers, Camerart.
With most welding what's needed is correct penetration, the welder gauges the heat and time for the best weld. The holes show there is either too much heat or for too long, so as it's better to get in and out as quick as possible, this equals more heat for less time, and heats the object (cell) as little as possible so with my demonstration all that need doing is to get the timing right. This will be done as I said with the correct pressure before the electric, then time the burst to suit, with electronics.
Hope this helps, (please don't hold me responsible, for my lack of accuracy).
Cheers, Camerart.
I made a battery holder using plastic conduit. As it's a bit small diameter, it needs cutting along it's length to the shape of a horseshoe, so it just clips the cells. Then add insulated 'washers' each end, with a hole drilled in the centre for a connection.
Cheers, Camerart.
Cheers, Camerart.
D
Deleted member 4366
Guest
It's current density that you need for spot-welding, so you need the smallest electrode diameter you can, but copper electrodes will heat up and soften if too small. Then on the next strike, they will squish flat. Some guys are doing it with brass electrodes, but I don't think that's ideal either. You probably want something like beryllium-copper.
Another aim should be to use a very high current for a short time by using large capacitors and electronic switching.
I've got a feeling that just using high current will be too slow, which will heat up the battery and damage it. It would be safer to solder because the temperature is a lot lower and controlled. I've soldered lots by putting a blob on the battery first with just enough time/heat to wet the solder. Then a blob on the strip. Finally, put the two together and reheat until the blobs fuse.
Another aim should be to use a very high current for a short time by using large capacitors and electronic switching.
I've got a feeling that just using high current will be too slow, which will heat up the battery and damage it. It would be safer to solder because the temperature is a lot lower and controlled. I've soldered lots by putting a blob on the battery first with just enough time/heat to wet the solder. Then a blob on the strip. Finally, put the two together and reheat until the blobs fuse.
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