Hi amp battery clamps - NOT!!

[Mosaic]

Ok..EBAY E-FAKES rant:
These clips/clamps:

https://www.ebay.com/sch/i.html?_od...attery+clips.TRS0&_nkw=battery+clips&_sacat=0

They may LOOK like copper but it's VERY thin copper plate.
I purchased some for a project and they are quite magnetic.

What's worse is that from tip to tip they ADD some 20+ mΩ to the resistance of the connection.

This may not seem like much...but since I am pulsing 500+A over a short duty...well, things still heat up quite a bit.

So, I took a page from the welding clamp approach (I arc welded a couple things 25 yrs ago- got arc eye and moved on) and inserted/soldered a 14AWG copper cable on both sides of the clip. Resistance losses drops to near nil.

 

[nsaspook]

Really, you expect quality for almost nothing?

 

[Mosaic]

Hope springs eternal...

 

[Inquisitive]

Try something like this

https://www.waytekwire.com/products/1374/Battery-Clamps/

Pick your amperage

 

[MrAl]

Ok..EBAY E-FAKES rant:
These clips/clamps:

https://www.ebay.com/sch/i.html?_od...attery+clips.TRS0&_nkw=battery+clips&_sacat=0

They may LOOK like copper but it's VERY thin copper plate.
I purchased some for a project and they are quite magnetic.

What's worse is that from tip to tip they ADD some 20+ mΩ to the resistance of the connection.

This may not seem like much...but since I am pulsing 500+A over a short duty...well, things still heat up quite a bit.

So, I took a page from the welding clamp approach (I arc welded a couple things 25 yrs ago- got arc eye and moved on) and inserted/soldered a 14AWG copper cable on both sides of the clip. Resistance losses drops to near nil.

Hi,

I had a similar problem with some wire i bought in a dollar store. Silly me, thinking it was a good deal. The only thing that wire was good for was use as 'rope'. The resistance was so high it would easily add an ohm to a 8 foot length, even though it was #18 AWG wire. Not only that, but the wire would not solder! That was the biggest surprise. I could not believe it as i never saw copper colored wire that would not 'take' solder. The solder just would not stick. I stopped using the wire and may use it as rope only, really.

 

[tcmtech]

Ok..EBAY E-FAKES rant:
These clips/clamps:

https://www.ebay.com/sch/i.html?_odk...attery+clips.TRS0&_nkw=battery+clips&_sacat=0

They may LOOK like copper but it's VERY thin copper plate.
I purchased some for a project and they are quite magnetic.

What's worse is that from tip to tip they ADD some 20+ mΩ to the resistance of the connection.

This may not seem like much...but since I am pulsing 500+A over a short duty...well, things still heat up quite a bit.

So you are saying a set of cheap clamps that are already likely very 'generously rated' for 100 amps are not holding up to 500 amp pulse work?

Go figure.

Having good luck using gum wrappers for high amp replacement fuses in your vehicles as well?

 

[Colin]

You should always double-up on jumper leads over 250 amps.

 

[Mosaic]

So you are saying a set of cheap clamps that are already likely very 'generously rated' for 100 amps are not holding up to 500 amp pulse work?

Go figure.

Having good luck using gum wrappers for high amp replacement fuses in your vehicles as well?

Did i say the duty cycle was like 2%?

 

[fezder]

i too made quie interesting find when i disassembled car-jumper (battery inside, cords to give car battery charge needed to start, you know?) clamps were good, but that wire, was~18awg, doupt that'll suit 400A, even battery had absolute maxinum of 250A, well i never used that thing though

 

[Colin]

Did i say the duty cycle was like 2%

It does not matter if it is DC or a pulse, the voltage-drop is the same.

 

[Mosaic]

The heating and resistivity change is different though.

 

[Colin]

The heating and resistivity change is different though.

The heating will add a small amount to the resistance, but the main resistance will come from the leads themselves.
If the leads have a resistance of 100 milliohms, the current-flow when using them as a jumper to start another car will only allow about 40 amps to flow.

 

[Mosaic]

That's all true.
But my post #1 discussed the clamps and a workaround. Not the leads at all.

 

[Colin]

The problem is not the clamps but the connection of the clamps to the battery posts.
That's why you need 2 sets of leads

 

[audioguru]

Today I was running my 120VAC electric leaf blower for about 1 hour and the extension cord is "heavy duty". Some of the cord was wound on the spool and boy-oh-boy it got HOT and smelled like it was hot but not smoking.
If anyone wants to know the amperage of the blower and the AWG of the cord I will look them up tomorrow when there is daylight.

 

[chemelec]

Today I was running my 120VAC electric leaf blower for about 1 hour and the extension cord is "heavy duty". Some of the cord was wound on the spool and boy-oh-boy it got HOT and smelled like it was hot but not smoking.
If anyone wants to know the amperage of the blower and the AWG of the cord I will look them up tomorrow when there is daylight.

The Amperage Rating on Bundled Wires is LOWER than a Single Wire in Free Air.

Example:
A Single 18 AWG wire can handle up to 16 Amps in Free Air.
Multiple 18 AWG wires is a Bundle are only good for about 10 Amps Maximum.

 

[MrAl]

Hi,

Yeah you have to remember that wire bundled up is like a coil, the only way the inner turn can cool is through thermal conduction. The heat has to conduct all the way through all the other wires and all the other insulation coverings.