1 hour ago, Beat said:

Talking battery cables reminds me a story:

Years ago a bought from Game a set of nice thick automotive battery jumper cables, guaranteed 200A. When it came to the emergency application they failed to start my engine. They only provided some charging current to my battery so I could after a while start the engine from my battery. I got suspicious and opened up one of the clamp handles. What I found was outrageous. The nice thick cables consisted of 99% insulation and just 1.4mm² copper. That copper was not even crimped to the clamp but only squeezed between the clamp and the insulation. I brought it back to customer service and got refunded. By the way, Midas sold the same product.

I then bought 6m of 16mm² welding cable and soldered 3m each to the clamps. I could start with them a 2l diesel engine from a 50Ah battery.

This is what I found used on a set of jumpers. Bought from Midas. Wire was about 3sq mm and plated with copper. It looked like aluminium wire.

Edited August 23, 20223 yr by Scorp007

On 2022/08/21 at 2:07 PM, Beat said:

Basically, physically only the total copper section determines the current carrying capacity. However the insulation temperature resistance determines at what temperature you can charge a conductor permanently. It depends also on environment temperature and cooling effects. I installed 25mm² welding cables.

However there is another issue not discussed yet. That's short circuit resistance. Consider the instant power available from a battery pack of 100Ah or even several in parallel. The cables must to be able to carry the short circuit current to trigger a breaker or fuse before blowing up themself. My four packs are each factory fitted with a 125A breaker. Then I have a 125A high power fuse in the collector line to each inverter. Personally I have more trust in fuses than in breakers, since almost all breakers on the market are conceived for AC. However DC is much more difficult to cut than AC. Fuse elements are inbetted in quartz sand that immediately fills the space of a melted element.

Due to the skin effect of how current flows, a finer stranded cable can carry more current for the same mm2. Look up electro magnetic theory.

On 2022/08/23 at 12:26 PM, Scorp007 said:

This is what I found used on a set of jumpers. Bought from Midas. Wire was about 3sq mm and plated with copper. It looked like aluminium wire.

Need that super thick insulation to protect you from that 12V 😂

56 minutes ago, run_the_race said:

Due to the skin effect of how current flows, a finer stranded cable can carry more current for the same mm2. Look up electro magnetic theory.

I think you need to revisit your above statement. 

In general, solid wire cables are better electrical conductors than stranded wire cables, and they provide superior, stable electrical characteristics over a wider range of frequencies. They’re also considered more rugged and less likely to be affected by vibration or susceptible to corrosion, since they have less surface area than stranded conductors.

• Solid wire can also carry more current than stranded wire. Higher-gauge (thinner) conductors have more insertion loss than lower-gauge (thicker) conductors; stranded cables exhibit 20 to 50 percent more attenuation than solid copper conductors. Because the cross section of a stranded conductor is not all copper (there’s some air in there), they also have higher DC resistance than solid cables.

Which type of wire is the best choice depends on the installation's requirements.

The reason for using stranded wire on battery curcuits they are much more flexible hence easier to use.

 

Edited June 4, 20242 yr by TaliaB

13 hours ago, run_the_race said:

Due to the skin effect of how current flows, a finer stranded cable can carry more current for the same mm2. Look up electro magnetic theory.

Skin effect is a phenomena of high frequency alternating currents. On batteries we are dealing with DC (direct current). And - to prevent skin effect with high frequency on stranded cables, each strand would have to be insulated individually. (Radio technology)

17 hours ago, run_the_race said:

Need that super thick insulation to protect you from that 12V 😂

The insulation is so thick to protect you from the red-hot aluminium...

Interested in what battery cable is as it it not mentioned as a type of cable in my cable list. My specs even mention some overhead cable but finer cables they only mention panel wiring and then welding cable. 

Solid also very few sizes.