It has been said soldering to Ni-Cad etc cells is a bad thing as the heat can damage them. Hence the pro method of welding which presumably transfers less heat to the inside.
Does the same apply to Lithium Iron?
Maybe more so, as I do not think Ni-Cd have a reputation for bursting into flames. :)
I've soldered NiCd, NiMH and Lithium cells without any noticeable harmful effect on the cells. You need a big hot soldering iron so contact time is minimised and some makeshift method of holding the cells upright. Abrade the cell top and bottom with sandpaper, wipe with IPA, put a drop of rosin flux on and tin each end. Immediately after finishing each application of solder hold a wet cloth against the join to cool it down. Tin the wire you are going to attach and apply the wire and solder together to the cell (which is why you need the battery "clamp") . Again press a wet cloth on the join as soon as it is made and hard.
I've never had any later leakage of any cell doing this and no noticeable degradation in their output or life.
I should have mentioned that if soldering to Lithium rechargeable cells this should be done at a low state of charge, they seem to be quite happy at high temperatures (they are autoclaved at 140degC for
20 minutes when used in surgical tools) but only at low state of charge.
It's "Ion", not "Iron".
+1
Actually, lithium iron cells do exist (LiFePO4).
And wear decent eye protection, just in case.
Besides the matter of excess heat, the casing is remarkably resistant to soldering. The same goes, at least in my experience, for other rechargeable cells.
You can but the thin metal strip to connect the cells off Ebay and I've 'spot welded' it to the cells with just a couple of bits of thick (2 or
3 mm) copper wire) and a car battery, using a simple wooden holder to keep the tips of the copper wire may be 2 mm apart. There are several videos on YouTube. You can make a proper jig/tool but, for the number of times I need to do it, I just use a 'lash up' as and when.You can touch the weld almost immediately, I normally make a few spots, so I assume the heat transfered into the cell is naff all.
There are some interesting videos of homemade spot welders on YouTube, based on rewound uWave oven transformers. I don't do enough metal work to need one but they look interesting tools.
Just waiting for some smart arse to notice and comment - without anything about the thread.
And you certainly didn't disappoint.
Thanks Peter. Looks like it's OK, then.
I'm sure they do, but they aren't what Plowperson is talking about.
And they are referred to as lithium iron phosphate or 'LifePo' Li-ion tabs are usually alumionium unless tinned brass has been spot welded to them. Soldering with al flux works.,
1+
Big iron, do it quickly, no problem. Use 60/40 solder which is nearly
40'C lower melting point than lead free.Cheers
And are rechargeable with a voltage conveniently slimllar to lithium primary cells. But hard to find.
I am interested all this because I was thinking of using a decent array of (ideally Panasonic) Li-Ion 18650 cells (possibly 4S25P) to act as a lead acid traction battery replacement for my electric outboard.
Long short, I don't think our usage pattern (the battery used unpredictably just a few times a year) is worth the cost an complication, simply for the (admittedly large) weight saving.
The 'complications' and in contrast to LA are that:
1) Li-Ion (and most Li chemistry cells for that matter) need, to ensure a reasonable life span be stored between uses at a 'storage' (charge / voltage) level. (By contrast, LA can be left on a smart float charger 24/7).This means that if we charge it, take it out but don't use it and if we aren't going to use it fairly soon, we need to discharge it down to the storage level again?
2) Because it needs to be stored at a 'storage level', if we decide at short notice that we fancy going boating, we wont have long to charge the battery up and whilst we could charge it from storage to full at 1C, that would require an ~80A charger! (By contrast a LA battery would be ready to go 24/7 and can generally be left unattended and could use a slow charger. They recommend any Lithium battery not be left unattended whilst being charged).3) It is very rare for a LA battery to spontaneously explode and / or catch fare and can't generate it's own oxygen so could even burn is space, unlike (I understand) Li-Ion). 'Sealed' (recombination) and especially GEL batteries are even less likely to ever cause an explosion (or catch fire) as they don't vent hydrogen and would only do so when charging in any case (e.g. The chances of anything untoward happening when in a boat some time from the shore would be very very low).
4) To maintain the Li pack properly and for the best life span and safety I would need a BMS that was capable of continuously passing 30A (the maximum draw of my current electric outboard) and managing the cells to a maximum charge of 80% (with balance) and a maximum discharge of 20% (with cell group protection). It is said that the worst thing for these cells is a poor BMS. (By contrast I would only need a 'low voltage' alarm for a LA battery as the only real risk of an over-discharge is reduced cycle life, or worst case, a damaged battery. Not an incendiary device going off in my boat). ;-(All that said, I would still like to put together a quality Li-Ion (or LiFePO4) 18650 cell pack but not sure if it wouldn't be too needy? ;-(
Cheers, T i m
Lead acids can set fire to things with their huge output current, or from poor connections. But they don't need fire to kill you, a battery producing boiling sulphuric acid fumes is no laugh. DAMHIKT.
I see no sense in your plans, the downsides surely outweigh the upsides.
NT
You need to reassess those claims. If you're going to put this on the water you will need a boat safety certificate. One of the requirements with be venting of the batteries.
I can assure you, batteries gas, and the gases given of are a perfect hydrogen-oxygen mixture.
I can testify to this, except I was lucky in that the caps flew into the air and I was covered in just a little acid, still sufficient to eat through my top (which I should have thoroughly washed in water).
If I recall correctly, where the main propulsion is electric, the CaRT licence is much cheaper. BICBW.
As can Li, but not generally on their own simply because you have over-discharged them.
Sue, but I'll be wiring it all up so there won't be any of those. ;-)
Whilst I'm not saying there are *no* risks, I'm saying there are much fewer risks than say with Li. Like, I can't remember where I read so much advice about you *must* never leave a lead acid battery on charge unmonitored or that you can buy a fire safe / bunker for charging, transporting or storing lead acid batteries in.
I don't think I need to .
Such as? I thought I made the pros and cons pretty clear and were no-brainers for our needs?
Cheers, T i m
No, you are right, for some authorities. I don't think the Canal and River Trust that cover the lies of the Lea and Stort differentiate between IC and electric propulsion (both come under 'Powered Craft), but I believe the Norfolk equivalent do (with a 50% licence duty reduction etc).
I did email the C&RT re how they define 'powered' craft.
Ok, we'll assume they wouldn't consider a person rowing 'powered', nor sailing but what if the sails were a windmill of some kind and driving a propeller or paddle wheels?
What if the human was not rowing but pedaling and that was driving the oars, or paddle wheels or a propeller?
What if that human pedaling was driving a dynamo and that was driving an electric motor (and a propeller or paddle wheels)?
What if there was a battery that was put into the boat with no charge, then charged by the human pedaling and then used to run the drive ... or charged a super capacitor (that isn't a 'battery') that in turn powered the craft.
Or what about the addition of solar panels ... etc etc.
My point to them was that whilst most pre-charged electric propulsion would have caused some pollution in gaining that charge, the 'waterside emissions' and the risk of chemical pollution (directly to the water) via petrol or lubrication oil was mostly reduced to zero. That along with the near silence of most electric propulsion should (IMHO) give it a reduced licence fee.
I understand we are still using the waterways (and possibly locks etc) and so should contribute *something* (towards their upkeep).
But I'm not doing a harry and asking other people to pay for me to use my boat! ;-)
Cheers, T i m
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