The Lotus Grand Tourers

Going to start this as ... I personally..

Would solder any terminals connections as the crush connection will eventually degrade as the copper is exposed. Potentially with these crush fit connections as well, the core of the main lead can break off under strain or movement.

When soldering these connections, I would actually use a large blow torch, thick solder and a decent amount of flux(most people don't have a high enough wattage soldering iron). The connectors will absorb a huge amount of heat before they allow the solder to stick.

1. Pre heat the connector holding it in a pair of pliers.

Your choice of solder is as follows:
Silver solder melts at circa 220c
Lead/tin solder is 270-300C
ROSSH compliant (lead free) is circa 320-350C

I use silver solder because it has the best conductivity and also flows at a lower temperature.

2. Flux connector.
3. Flux cable and "tin" cable
4. Heat connector again, insert cable and solder in place.

This should give you the best electrical contact achievable.
Bear in mind the thicker your cables are and the larger surface area to the contacts on your battery terminals the more efficient they will be.
Larger surface area and thicker cables means the lead will heat less and more current can be drawn without stress, especially noticeable when cranking the engine as the current draw from the starter motor is significant.

Yes that seems sensible. I think I would solder "off car" too. How do you prevent in insulation from melting though when tinning the cable?
Cheers
Mike

I use a hot air gun when soldering large terminals.

Pete

Some hot air guns as Pete points out can reach 350-400C and provide ample coverage. The better heat guns have different nozzles to direct the heat.

I use a heat shrink that you slide on before soldering the connector and then you can slide it over the joint and shrink once it has been completed.
Sounds a bit weird but on larger cables with thick insulation, lightly wetting the outside of the insulation material helps cool it enough not to smoulder but doesnt cool down the copper.

To properly prevent smouldering of the insulation during soldering is more down to practice though.u

Well practice makes perfect I guess. I was worried that that would be the answer as like a lot of the jobs Ive done recently, I just dont do them often enough to get good at them.
Looks like I'm in for a lot of melted termini before I crack it then!

In the back of my mind I had the idea that soldered joints were never used in cars, as a soldered joint is brittle and eventually cracks due to vibration.
Instead electrical joints are always crimped, or whatever.
Please let me know why soldering is OK in this case.
Confused from Yateley

tonypoll wrote:In the back of my mind I had the idea that soldered joints were never used in cars, as a soldered joint is brittle and eventually cracks due to vibration.
Instead electrical joints are always crimped, or whatever.
Please let me know why soldering is OK in this case.
Confused from Yateley

That's the way I understand it too.

I've done both over the years and have found that crimping (spades, rings etc), reinforced with an inch of heat shrink, is very resistant to vibration. The heat shrink is brilliant. I had multiple failures (crimped or soldered) on the Clan's alternator connections due to engine vibrations until I added heat shrink to the crimping.
There's an auto electrician or 2 on the Imp forum who would add support crimping over soldering too.

Mind you -that's coming for someone who has just suffered a period of random misfires/cut-outs due to a loose spade connection on the coil (wire was well attached to the spade though ).

I definitely crimp all small connectors and also use heat shrink. I also crimp battery terminals now, but the crimp tool cost a fortune!! I'd probable still prefer a soldered battery clamp to one fixed with screws. I think the flux has something to do with cables fracturing as well.

Pete

In the case of the battery terminal, it wont be the solder that fails, it will be the cable going into it.
On cables mounted to engines, you need a degree a
of flex as the drivetrain rocks to a certain degree.

Where the cable will fail is the wire directly outside of the terminal, this is the ideal spot to reduce tension by means of heatshrink to provide added support and relief.

Worth noting though the terminals I use are in fact crimped and soldered.
I will load a picture later, the terminals on the battery are bolts, so a different connector is required.
It will make sense when you see it.

- A good quality flux wont make the joint brittle, it should in fact strengthen the bond as it cleans the surface during heating and the residue should sit external to the bond after soldering. Use too much and it can be cracked off like slag when welding.
You could also use an Aquaflux when soldering, this is water soluble and leaves an ultraclean joint when washed off. Highly corrosive if left on too long though. Tends to be used in applications where flux residue is considered too conductive like hv joints.

Hi Again all- I have now had a chance to try crimping on a 35 sqmm cable using an 8 tonne hydraulic crimper from Ebay- v cheap at around £15 although quality unknown. However, although this seems fine for the eyelet crimp-on terminals, its not as effective on the solder-or-crimp battery post terminals. I see from a you tube vid that a "different" setting is needed for these thicker and more resilient terminals- but that vid failed to say what the differences actually were! I tried, but found that grip fell well short of acceptable (or even present) and when crimped in some more the terminal just fractured. Does anyone know how the post terminals should be crimped? Failing this I will revert to plan "A" and solder these.
Thanks
Mike

I eventually did sort a crimp that works- its described towards the end of the relevant blog here: [url]http://majcd213.blogspot.co.uk/2017/01/ ... ables.html