The Battery Cable Debate

[andy29847]

I got my heat shrink in the mail today. All I'm waiting on is the buss strips. I went ahead and made one cable. I was satisfied with how it turned out. One thing I noticed - the big power lugs are going to make it impossible to stack 2 cables on the existing posts. I'm guessing I'll need a few clamps with a taller post or one of the military style clamps. Let me know if youse guys have ideas.

The old cable I took off was near the end of it's useful life. I am sharing a couple of photos below so you can see what I mean.

[richard5933]

Originally Posted by andy29847

I got my heat shrink in the mail today. All I'm waiting on is the buss strips. I went ahead and made one cable. I was satisfied with how it turned out. One thing I noticed - the big power lugs are going to make it impossible to stack 2 cables on the existing posts. I'm guessing I'll need a few clamps with a taller post or one of the military style clamps. Let me know if youse guys have ideas.

The old cable I took off was near the end of it's useful life. I am sharing a couple of photos below so you can see what I mean.

You can get extenders for the studs on the batteries. Here's just one example: https://www.zoro.com/battery-doctor-...oaAv9GEALw_wcB
Check out a battery store near you and I bet you can find something locally.

[andy29847]

Originally Posted by richard5933

You can get extenders for the studs on the batteries. Here's just one example: https://www.zoro.com/battery-doctor-...oaAv9GEALw_wcB
Check out a battery store near you and I bet you can find something locally.

Thanks for the note. The extenders look like they will work for me.

I mounted my crimper on a 2x10. Secured it on the board with a single strap. It gives me the "extra hand" I need to make the first crimp.

[jcag]

Here is some food for thought.
The reason why we, over time, need to change out our batt cables is because the electrical connection between the cable and the wire connector (no matter what kind of crimping process we use on the lug is) is that corrosion between the wire lug and the wire sets in. It has always been my practice, after crimping the lug to the wire, is to solder the two together. It forms a gas tight 'weld' and corrosion can never occur.
Secondly, I always use locking nuts to secure the lug to the battery. There is pro and con about using a split locking washer as well; my preference is to use a star locking washer. I will use a star washer for a better and more uniform, gas tight, connection between the nut and the lug. Some will put the star washer between lug and the battery, and compress it between the two components with a locking style nut. I think it is way overkill but thought I'd mention it. The object is to create a 'gas tight' connection between the wire lug and the battery post so corrosion can't set in over time. Again, this is my opinion and practice.

[Winemaker2]

Suffice it to say there are believers in soldering and non-believers.
I have never had to replace a crimped terminal lug.
I have retinned some where the bare copper was exposed and corroded.

[richard5933]

Originally Posted by jcag

Here is some food for thought.
The reason why we, over time, need to change out our batt cables is because the electrical connection between the cable and the wire connector (no matter what kind of crimping process we use on the lug is) is that corrosion between the wire lug and the wire sets in. It has always been my practice, after crimping the lug to the wire, is to solder the two together. It forms a gas tight 'weld' and corrosion can never occur.
Secondly, I always use locking nuts to secure the lug to the battery. There is pro and con about using a split locking washer as well; my preference is to use a star locking washer. I will use a star washer for a better and more uniform, gas tight, connection between the nut and the lug. Some will put the star washer between lug and the battery, and compress it between the two components with a locking style nut. I think it is way overkill but thought I'd mention it. The object is to create a 'gas tight' connection between the wire lug and the battery post so corrosion can't set in over time. Again, this is my opinion and practice.

I posted a link earlier to Trojan advice for doing just this - soldering AFTER crimping a lug to the cable. I've seen people tin the wires first, and this is not advised as it will result in a crimp connection which loosens over time.

A properly made crimp connection should not take much solder at all, maybe just a tiny bit around the point where the cable enters the lug. If it takes much, then there is air space inside the cable indicating it wasn't fully crimped.

[gpounder]

Novice answer - You don't need a meter or a chart. Turn on the microwave, using the inverter and touch the battery wires and terminals. If any get warm then upgrade the wire. Make sure terminals are clean and tight.

[richard5933]

Originally Posted by gpounder

Novice answer - You don't need a meter or a chart. Turn on the microwave, using the inverter and touch the battery wires and terminals. If any get warm then upgrade the wire. Make sure terminals are clean and tight.

Joking, right??

[gpounder]

Originally Posted by richard5933

Joking, right??

No not joking, after a 109 messages explaining the ins and out of the science of battery cables it all comes down to one thing, that is lowering the voltage drop as low as reasonable to get better performance from the electrical systems.

She has an existing system, we are not designing this from scratch just upgrading it to be the best possible within reason.

So.... as I said - "You don't need a meter or a chart. Turn on the microwave, using the inverter and touch the battery wires and terminals. If any get warm then upgrade the wire".

A warm wire will show weakness in the system. It is that simple.

[richard5933]

Originally Posted by gpounder

No not joking, after a 109 messages explaining the ins and out of the science of battery cables it all comes down to one thing, that is lowering the voltage drop as low as reasonable to get better performance from the electrical systems.

She has an existing system, we are not designing this from scratch just upgrading it to be the best possible within reason.

So.... as I said - "You don't need a meter or a chart. Turn on the microwave, using the inverter and touch the battery wires and terminals. If any get warm then upgrade the wire".

A warm wire will show weakness in the system. It is that simple.

I was really hoping you were kidding...


Needless to say, this is not the recommended method for determining proper wire gauge size. It's kind of like telling someone to go walk on the ice to see if it's thick enough to hold them. When they find out it's not going to hold them up it's already too late.

Sure, in obviously overloaded circuits the wires will get warm, but just like with the thin ice the problem here is that if the wires are warm it's possible that it's too late. The goal is to size things properly so that you avoid doing any damage or creating a dangerous situation, not to play guessing games with wire size.

Plus, there are so many variables in appliance and inverter sizing that in some cases your method will not really show anything, but eventually the inverter will be loaded to its max and then the problem might be discovered in a tragic way.

[gpounder]

Originally Posted by richard5933

I was really hoping you were kidding...


Needless to say, this is not the recommended method for determining proper wire gauge size. It's kind of like telling someone to go walk on the ice to see if it's thick enough to hold them. When they find out it's not going to hold them up it's already too late.

Sure, in obviously overloaded circuits the wires will get warm, but just like with the thin ice the problem here is that if the wires are warm it's possible that it's too late. The goal is to size things properly so that you avoid doing any damage or creating a dangerous situation, not to play guessing games with wire size.

Plus, there are so many variables in appliance and inverter sizing that in some cases your method will not really show anything, but eventually the inverter will be loaded to its max and then the problem might be discovered in a tragic way.

You missed the point, this is a working system that someone already designed it to work. She is just try to make it a bit better.

I have seen a perfectly looking wire get warm just to replace it with the same size and it stays cold. A volt meter reading also proved the slight loss. I got 40 years of dealing with batteries and solar. Sometimes you don't need to be a EE to figure out a real simple way for the laymen to solve the problem.

[richard5933]

Originally Posted by gpounder

You missed the point, this is a working system that someone already designed it to work. She is just try to make it a bit better.

I have seen a perfectly looking wire get warm just to replace it with the same size and it stays cold. A volt meter reading also proved the slight loss. I got 40 years of dealing with batteries and solar. Sometimes you don't need to be a EE to figure out a real simple way for the laymen to solve the problem.

I didn't miss anything - the standard for choosing a wire is not whether or not it gets warm. No fancy calculations are necessary though, just some simple math.

For all the OP knows the original cable was undersized as well, and it would take about 5 minutes to check the max draw on the batteries (usually the max the inverter is capable of drawing) and then using a simple chart to make sure the wire being selected is the proper size for the anticipated max load. As you're saying, part of the goal is to make things better.

If someone uses the "is it getting warm test" and finds that it is, in fact, getting warm, are they then supposed to guess what size to try next?

There's a reason things like wire size charts exist.

[neoflyer]

I think I will go with welding cable for my batteries because I have them on a tray and need the flexibility. Somewhere on this thread I think someone said there are more than one type of welding cable a particular type is best for battery cable. I believe it had a name. Short of going through all 8 pages of messages in this thread does anyone remember that? The message number would be great but anything is appreciated.

Ed

[andy29847]

richard5933 said this: Cautionary note for those using welding cable. When I made the switch to welding cable for my house batteries it was pointed out to me that not all welding cable is created equal, and some has a distinct difference from standard battery cables which can become a problem.

The difference lies in the outer jacket - the batteries cable outer jacket is typically rates for direct contact with fuel, oil, and grease. It will resist breaking down with such contact. Some welding cable is the same, but there are varieties of welding cable which is not tolerant of fuel, oil, and grease.

If you are using the welding cable in areas like an engine bay, be sure that it's rated properly so it will not deteriorate from the kind of dirt it's likely to encounter there.

Other than that, I couldn't find a reason not to use it, especially when having to route it through difficult to route areas.