Renewing power cables on the T/A

[TransAmDan]

Not starting the work yet, once the garage is done. I'll get this done. The T/A is on my aunties drive way at present.

Some time ago I had troube with an earth and it showed up on the lights. At a car show in Waterlooville I was investigating earth. There is an earth stud on the wheel arch in the engine bay. Tried to undo it to check the joints, the stud was rough and curroded. Moved the battery cable to another earth point on the car and things were better. To this day that earth is still in that temporary point.

So my ain is to put on a new earth point. run a new port cable to the starter. New earth cable to the block, and new power cable to the alternator.

I have ordered the crimp tool, and a variety of crrimps for 8mm and 10mm studs and other sizes too. Wasn't sure what size wire to use. I have used 16mm2 on power cables at work, and they were pretty hefty. So went for 25mm2 for the car.

Ordered online, and arrived really quick.

What size is usually run to starters? 25mm2 is smaller than I was expecting, it does have it written on the cable. I dont have the T/A here, perhaps this is the same size that is already on there.

 

[TransAmDan]

Interesting calculator on https://www.12voltplanet.co.uk/cable-sizing-selection.html

Cable will be under 1 meter in length, and @ 25mm2, running a starter, not sure of current draw, read somewhere its 170A, but it guess it depends on starter and what it is turning. So say we are 170A load, we only have a .23volt drop which is 1.92% of the supply, so its in the recommended range.

 

[saleen 192]

Can't beat OHMS Law.. Also solder and heat shrink cable ends if you can as they are open to all weather conditions

 

[AmericanThunder]

Oh yes

V
I R

been years since I last saw that!

 

[TransAmDan]

And
P
V I

My original concern is what is the usual thickness of battery cables, as I wanted to buy the same or better. The starter is the largest current draw, but I didn't know how much current they tend to draw. Since found out its 50A to 150A in usual operation. However if a starter goes bad it could be up to 250A.

 

[saleen 192]

Is that not a spec for the starter motor? Wats the crank amp of the battery mybe 70amp hour but the crank amps normally for around 30sec with be massive 540 to 600 plus this is normally on the battery. But good that you going ot for the cable. I see from pic you gone for fine strand cable make sure you crimp it well and heat shrink the ends as the fray where you crimp them.

 

[renchero]

i just went for the biggest cable i could get i think its 40 mm on the starter and 25 to the alternator. ott but very little volt drop

 

[TransAmDan]

Sounds good. Looks like 50mm2 is available, and my crimp tool will do that size, its the max it will do. I'll check what bolt holes I need, or may just get a bag of 10 of 8mm and 10mm holes. I'm sure they will come in useful if someone else needs a cable made. I'll pop on 50mm2 on the starter, and use the 25mm2 elsewhere, like alternator and cable to the fuse box.

 

[TransAmDan]

My plan is to run 25mm2 to the alternator and chassis.
50mm2 direct to the starter and the block. I know the starter and alternator are 8mm studs, so got the appropriate crimps for it.

 

[TransAmDan]

Also new battery clamps, takes 50mm2 25mm2 and 2 smaller ones.

Not going to have a chance today to do cables and swap put the alternator as the TA isn't here, and can't get in the garage just yet. I plan to do this work next weekend.

 

[TransAmDan]

Tried out the crimp tool on the 50mm2 and 25mm2.

Added a bit of heatshrink sleeving to finish it off nicely.

Also cut some slithers of glue gun glue to put under the heatshrink that flows as you shrink the shrink wrap.

 

[saleen 192]

Doh could of used red heat shrink for red cables lol, but good job as that stops or at least stops the thin multi strand cables fraying breaking

the right hand crimp looks looks like it's split torn when you crimped it so its now weakened,

 

[TransAmDan]

While working on the sump during the Kmember swap it helped removing the starter. This gave me good access to the main 0V cable between the battery and the block. The cable was fine, chose to put on thicker cables. Left is the original, must be 16mm2. A nice 50mm2 is now fitted at that end. Also changed the main power cable to the starter, same thickness. I have run them towards the battery. I'll connect that after completing the rest of the work.

 

[renchero]

might have said this before but after i put thicker leads on the ranchero the starter motor turned noticeable quicker

 

[TransAmDan]

might have said this before but after i put thicker leads on the ranchero the starter motor turned noticeable quicker

Yeah, it should improve things, less volt drop in the cable. Since I put on the new 1000A battery the starter has been quicker, and with this new cable that starter is going to get some good juice, its a fairly new starter too, perhaps 2 old. Hope it dosn't like to see a volt drop as its not going to see one.

If 16mm2 cable used, and starter draws 100amps, then you loose 0.21v, in 1 meter of cable.
If 25mm2 cable used, and starter draws 100amps, then you loose 0.14v, in 1 meter of cable.
If 50mm2 cable used, and starter draws 100amps, then you loose 0.07v, in 1 meter of cable.

All the above is okay to use as its less than 3% volt drop of the supply voltage.

With the new cable I could draw 520amps to be at 3% drop of the source voltage. Old cable would be 170amps.

 

[AmericanThunder]

And you will easily draw in excess of 520amps during cold cranking.

 

[TransAmDan]

Going to 'beef' up a few more cables on the T/A.

There is a thin earth strap, about 4mm wide and flat, its braided copper going between block and alternator.
I know the block has a good earth as on the other side of the block is a 50mm2 cable direct to the battery. I wannt make sure I have a good earth to the alternator. I know the positive power is good, 25mm2 direct tothe battery.

So I have made 3 cables, the short one, is from the block to the alternator bolt, the medium one is from the alternator bolt to the local chassis earth point. The long one is to join that local earth point to the earth point right next to the battery. The long one and medium one is a bit redundant as we 'could' rely on the chassis earth. As I was making cables and I had a spare length, I went with it. At least I'll be able to see a cable from the 0V alternator to the battery.
All a bit over the top, but why not. So thought I'd post a piccy.
I'll connect them up tomorrow evening.

 

[renchero]

i think if you do a before and after voltage reading you will see an improvement

 

[TransAmDan]

Got a small issue. Alternator not charging.

Before the Kmember swap it was working.

During the Kmember swap I beefed up the cable to the starter and also the 0v to the block next to the starter.
Put the alternator back on, 12v cable connected, the 4 pin connector with its single wire. There is a was a braided cable that went to the block near the alternator and the chassic. Took it for its mot. Alternator not charging.

So thinking the alternator wasn't getting a good 0v as it relied on bolts through brackets. So I made up good 0v cables. Got a good earth now. Started the car. Still not charging. Turned the car off measured volts at the pos alternator terminal to the alternator case. Good 12V, so my pos cable is getting to the battery, I can see the two ends of the cable. So the 12v and 0v cables have got be good. What about the 4pin connector? Alternator made in China, duff already?

 

[TransAmDan]

After further reading of alternator connctions, with only 3 wires what can go wrong? I know the 0V and 12V heavy duty cables are good. What about the 4 pin connector with a single wire?

Well this wires can be a charge sence for a bulb on the dash, or in some cases it is an enable to enable the voltage regulator to output the charge voltage. So I wanted to disconnect this connector and make a measurement. Is there around 12V on this when ignition is on?

Took the connector off and the wires feels good, not broken, oh wait, the crimp has been pulled from the connector. This may have happened when I was removing the alternator.

Dismantled the connector and pushed this in. its nice and snugly at home now. If the connector gives more issued you can but these with pigtails fitted so I could always solder in a new one. I think it should be good now.

Charge voltage where it should be.

The garage smells great now.

Thought I'd take a photos of my battery wiring.

The battery is big, its just the thicknes of the cables and the large connectors that make it look small. 50mm2 red to the starter, 25mm2 to the alternator and fuse box,m tiny red to the battery charge connector. 50mm2 black to the block near the starter, 25mm2 to the earth point nearby. small black/red to the charger. Then from that 0V earth point near the battery this goes to the alternator fixing bolt, and a shorter wires from that bolt to the block.