BB. wrote: »
Also, there is more "air gaps" in the fine stranded cables. This means that normal crimp connectors are usually too small to fit the same size cable crimp connector (8 awg course stranded vs 8 awg find stranded) and if you get a larger size, they do not crimp small enough to hold the strands.
I needed to find very fine stranded heavy cable for -48 VDC power system (very tight space) and it was a pain to find UL listed cable and crimp terminations.
BB. wrote: »
Tin/Lead solder is, roughly, 1/10th the conductivity (or 10x the resistance) of annealed copper.
That is why it has been reported that high current/lightning strikes have "blown" the solder out of copper wiring connections (in my humble opinion).
It is certainly also possible to melt a solder connection (relatively low melting point) vs the copper itself (relatively high melting point).
A proper crimp connection should be "gas tight" and solder should not flow into the area between the crimp ring and the wire.
The annealing temperature of pure copper is ~736 Centigrade. Although, it appears that copper wire can start annealing at temperatures as low as ~150-200C. Solders melt around 175 to 220 C (tin/lead to lead free).
So, there would appear to be a risk of annealing the stresses in a crimp copper connection--Something I would guess that is not a good idea.
This "high temp" copper crimp connection is rated to 650F or 343C -- So, perhaps the ability to anneal copper at the temperature of solder is not a big issue?
BB. wrote: »
Silver solder is near copper in conductivity and is much stronger than tin/lead.
However, I would avoid soldering in general. The issue of joint resistance is not really my main issue... It is that soldering is difficult to get right (and silver solder would probably be even more difficult) and the issue of creating a point of "flexure". When cables are flexed, the copper is work hardened right at the point where the solder stops.
There can also be some issues with corrosion (flux wicks it way up the strands of the cable). Of course, use non-corrosive flux, but still not ideal.
I have never silver soldered cables--So I don't know how well it would work (or not). It has been 4+ decades since I have done any silver soldering (mechanical sections).
Looks like Silver solder may run in the range of $30-$40 per Oz in small lots vs something like $30 for 16 Oz for lead free solder (plumbing).
If you are going to make more than a few battery cable connections, I would highly suggest looking for a proper crimping tool and contacts.
Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.
Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.
lexington wrote: »
1.Which gauge of wire will be ok for 96VDC, carrying 75amps maximum over 4m? will it be a AWG 6 or AWG 5?
2.Cables here are sold in 7-strand, single core and fine strand cables. i will need to maneuver the cables from Inverter and battery into the combiner/breaker box which would be ok?
3. would you recommend crimping alone or soldering? soldering such large diameter cables would be pretty hard to do in these parts, as soldering machines to handle it are hard to find.
your inputs and posts are appreciated.
2manytoyz wrote: »
I work in the aerospace industry. Per our regs, we can either solder, or crimp, but we can't crimp and solder. FWIW, either are acceptable methods for flight hardware.
Part of the issue is trying to crimp a soldered connection. The solder doesn't compress as well as unsoldered copper wires. Ends up failing a pull test. Also, if the connector gets hot, the solder can melt, and things can get "interesting" as the wire starts to slide out of the connector. This is why big power cables use compression fittings, not solder.
Some of the industrial crimpers for large wire compress the termination so hard that the wire is almost fused together. I've seen pics of these cut apart after crimping, nothing short of impressive. I don't expect YOUR crimper to have these results.
I have soldered connectors after crimping. It probably made no real difference, but it looked better having the ends of the wire tinned, and a nice solder fillet to the lug. That said, this was only on small conductor cables (~10 ga).
Once I started moving up in wire size, soldering became much more difficult. Takes a lot of heat to get solder to flow in the ends of fat wire. Even with 6 ga wire, I ended up using a solder pot to tin the wire, then pre-tinning the inside of the lug, and finally heating up the wire and lug just prior to cramming them together.
We are also required to have the insulation back about the thickness of the conductor for a visual inspection, prior to covering it with heatshrink. This wasn't a work project, but old habits...
I must say, soldering 6ga wire was PITA! No way I'd attempt that on 4/0 cable. I use an anvil type crimper instead. Makes decent crimps in a fraction of the time.