How to make better battery cables
Correct cable to make battery-cables from.
Why crimping is the correct method. Not solder. (With real world examples)
How crimping works.
Tools necessary. How to use them.
Where to source the terminal posts from.
How tight to do battery terminals
Why battery-post terminals are the BEST terminals method. Compared to other shite.
How to find a suitable chassis ground in a relocated battery instance.
Expandable-braid vs DR-25.
Terminal covers and why you should use them.
Why would you even need to make some?
What’s wrong with the oem battery cables? For majority of people absolutely nothing. They work and are on vehicles that have over 300,000miles and continue to work fine from a design stand-point. So what gives? Why fix what’s not broken? Like most things there is no one definitive answer to the question. So let’s briefly discuss it.
Okay, so number one. Just talking battery-terminals with the existing cables. Your terminals are damaged/broken and you are left with a defective part. Visually strands of wire are hanging out the battery-terminal where the conductor is stripped bare and is attached to the battery-terminal. For those unaware, this is a very serious issue and will, not could. Definitely create a servre problem. Such as the remaining strands effectively acting as a smaller gauge wire and not up to the current demand that the oem gauge wire is designed for. So the wire would then becomes a fuse and it would melt and you could have a fire and to top it off you’d be stranded on the side of the road! Absolutely knackered. So you’re looking to put new terminals on the oem cables. Quite a common job for vehicles that are prone for poor battery terminals from the factory. Poor wiring is a common issue on French vehicles, typically older French vehicles. So you’re looking to put new terminals that are a upgrade from the poor oem part.
Onto number two. You’ve got a project vehicle or the vehicles wiring is none existent or has been in a fire. You’re trying to mimic the factory wiring but upgrade the battery cables at the same time. You’re replacing end to cables. So from starter motor to the battery and depending on the vehicles wiring configuration. The wiring from the alternator to the battery or most likely the link between the alternator and the starter motor. Then from the battery to the fusebox. Replacing every leg in the system.
Thirdly, you’ve started a battery relocation and need new cables that never existed before in your vehicle. If you’re looking at doing a battery-relocation on a NC MX-5 or want to see my simple relocation setup. Please check out my NC battery-relocation article found here. In this articles tutorial I will be creating the cables from the new MTA power-distribution box to the positive battery terminal. In addition the necessary ground cable from the chassis to the negative battery terminal.
Okay no we have a reason. What’s the correct materials for success?
So let’s talk about the tools you’ll need for this job. You’ll need a crimper (either hydraulic-operated or manual/hand operated) that will crimp the crimp-lug that’s sized to slide on the end of your cable. A heat-gun, you can get away with using a hair-dryer or blow-troch. Worth mentioning if you’re using a naked flame to recover heatshrink pay attention to keep the heatshrink far away from the tip of the flame and keep moving the heatshrink (the crimped end of the cable) around 360 degrees and up and down. You DO NOT want to focus on one particular spot when recovering heatshrink regardless of the heat source used. But due to the immense heat of a naked-flame from a blow-torch the time and ultimately room for error before you begin to melt the heatshrink and highly likely the cables insulation, is reduced. You’ll need some scissors to cut the heatshrink to the correct length. Some means of cutting the cable end as square as possible. You can use some ratchet-cable shears or hand croppers. Or depending on the size of the cable a junior hacksaw or a regular hacksaw. Worth mentioning a hacksaw will squish the end of the cable considerably more than the alternate methods mentioned.
You may have heard of crimping when it comes to large battery cables. You might not. You may have heard of soldering battery cables. I’m going to tackle this question head on. Why crimp over soldering or using those horrific set-screw terminals. Soldering repetively while being consistent is a serious skill. Soldering requires more tools and equipment such as lead-solder, rosin-flux, soldering-iron or gun, heatshrink. Where as crimping is a far simpler method of securing crimp-lugs to the end of cables. They are actually used in industrial electrical infrastructure to connect sub-main cables from their respective supply. So it is a common practice for small to large cables.
To carry out a successful crimping operation the user only needs. A crimper either manual or hydraulic, 3:1 glue lined heatshrink and a crimp-lug with the correct size for the cable and diameter hole you have determined you require. That’s it. Meaning with the very basic technique required to perform a successful crimping operation if I completed one end of the cable. You’d be able to complete the other end and it would be to the same standard as the my end. Crimping essentially is performing a cold-weld as you crush the tinned copper tube-terminals (crimp-lugs) to the copper strands of the stranded cable. Crimping is preferred to soldering, as soldering creates a more brittle (hard) connection. Good practice for soldering is usually incorporating a mechanical strain-relief method to take the strain off the solder-joint. Where as with a cold-crimp joint there’s no need. Crimping will allow a more flexible bend radius from the crimp-lug as you don’t have solder (especially if you have used rosin-flux) that has wicked up the strands and made the joint longer. That’s why when soldering is required say in a oem connector, the user will submerge the multiple solder joints in potting compound. This is a specific type of epoxy made for this purpose. Proving the requirement for solder joints to need mechanical strain-relief. Crimping of course is also a cold process and does not require ire safety equipment such as the correct type of fire-extinguisher nearby when soldering (hot works).
I touched upon the tools and parts needed to perform a successful crimp above but less dive deeper.
Let’s start with the crimp-lugs themselves. Often referred to as tinned-copper tube terminals. They come in slightly different designs, they can come flat or as a 90degree, with a bell-mouth or straight cable entry, different size holes to secure the crimp-lug down via the respective bolt. The bell-mouth cable entry is the better style and far easier to slip over the end of your stripped conductor (strands). Don’t be fooled thinking that 90degree crimp-lugs are just bent straight crimp-lugs. They are indeed longer to account for the length loss of the bend. The amount is critical for the crimp-lug to clear say the fusebox or whatever it is fouling against below. You’ll probably never use 90degree crimp-lugs but it’s best to know the difference and that they exist. Some crimp-lugs come with a shorter or longer stepped-down flat section where the hole is drilled and positioned to secure the crimp-lug down. Generally speaking this isn’t going to cause in an incapability issue however it is worth noting.
The heatshrink you need to use is labelled 3:1 shrink ratio. This 3:1 ratio heathsrink has a inner glue lining that melts and forms a water-resistant seal around the cable and the heatshrink. Regular run of the mill heathsrink is not suitable for this use. Remember to size your heatshrink accordingly to the size of crimp-lugs you are going to be using outside cable diameter. You want heatshrink that fits over with no hassle yet is a close size to the recovered size it’s going to be after the heat exposure.
Moving onto the main tool itself. The crimper! There are two different types of crimpers that are commonly used or electrical purpose. That is hydraulic and hand (manual) crimpers. Hydraulic crimpers are more expensive however the dies they take depending on the size the crimper will go up to. Are a wider crimp zone. Eliminating the preference to double-crimp when using a hand operated crimper where the crimping zone is narrower. As seen on my MX5’s cables in this article. That was performed by a hydraulic crimper. Not my own personal hand crimpers. When purchasing a crimper it is absolutely necessary to know the maximum size battery-cable you intend to ever crimp in the future to ensure you have a crimper that is able to successfully perform the operation by having the correct dies and force required. The crimper will come as a complete set with the dies.
General electrical tools are needed too such as scissors or electricians-scissors, stanley-knife, cable-croppers or ratchet-cable-cutters or a junior hacksaw or hacksaw. But be warned about using a hack-saw as mentioned above in regard to the cable end becoming more square which may lead to difficulties fitting into the crimp-lug once stripped to bare conductor. A heat-gun or hair-dryer are the most appropriate sources of heat that reduce the risk of burning the heat-shrink and the cables insulation. However a naked flame such as blow-torch or lighter will do just be so careful not to allow the naked-flame to touch the cable and heatshrink and to work very quickly and keep the cable and/or heat-source moving around fast to avoid melting either the cable or heathsrink.