So you need thicker leads for tailcap readings... where do you buy them?

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radiancez567
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So you need thicker leads for tailcap readings... where do you buy them?

Using my Excel XL830L cheapie multimeter, just tried measuring some tailcap readings and get consistently lower readings.

Leads too thin? I’m using some leads that labels itself as MASTECH 1000V CAT III 10A, bought it at local supermarket.

Would a Fluke test lead be good?

I’m expecting some people to reply DIY own test leads (btw can’t find any good guide to DIY thick leads), but I’m wondering if there are ready-made around.

Edited by: radiancez567 on 01/31/2013 - 13:06
ryansoh3
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What does the resistance read when you short out the two probes?

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NightCrawl
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Those leads are usually all way too thin. I use 2.5mm² speaker cable (AWG14 for US people), croco clips and banana plugs that fit my Multimeter.

BIGWOOD
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radiancez567 wrote:
Using my Excel XL830L cheapie multimeter, just tried measuring some tailcap readings and get consistently lower readings.

Leads too thin? I’m using some leads that labels itself as MASTECH 1000V CAT III 10A, bought it at local supermarket.

Would a Fluke test lead be good?

I’m expecting some people to reply DIY own test leads (btw can’t find any good guide to DIY thick leads), but I’m wondering if there are ready-made around.

I have those leads on my Fluke. I suspect they too will give you lower readings as they do for me. They are just too long. Good quality but 1.2 meter long.

radiancez567
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ryansoh3 wrote:
What does the resistance read when you short out the two probes?

Around 80ohms inconsistent.

radiancez567
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NightCrawl wrote:

Those leads are usually all way too thin. I use 2.5mm² speaker cable (AWG14 for US people), croco clips and banana plugs that fit my Multimeter.

That’s nice, quite a lot of wires intertwined together.

BIGWOOD wrote:
I have those leads on my Fluke. I suspect they too will give you lower readings as they do for me. They are just too long. Good quality but 1.2 meter long.

Ok then I won’t buy it. Any thick leads to suggest?

Mr_Krabs
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Most people make their own leads. A set of banana plugs and thick speaker wire work well. I don’t even have probe ends on mine. They are short only about a foot long and 16 gauge wire and the ends of the wire are tinned. That’s alll minimal parts and length so there’s practically no resistance to get in the way of a reading.

garrybunk
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I too wouldn't mind knowing where to buy some thicker/better leads for "general use".  My real test leads are broken (been using them this way for years and sick of it).  I have homemade leads for current testing, but I don't like the stubby tinned ends for "probing". 

-Garry

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Blord
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Try HobbyKing. They have thick silicone wires. Even 10AWG wire is possible Smile

Werner
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Hobbyking has golden banana plugs and silicone wire these will make nice custom made cables. They also sell shrinking tube for about nothing.
AWG16 and down should make nice cables.

Mine are made from 0.2m long 1.5mm^2 super flexible wires, I tinned the ends. I also solder them direct in circuit to measure led current instead of crappy crocodile clips.

I am planning to make some thick crocodile clips myself when fasttech stocks silicone wire.

If you don’t want to make them yourself you can buy a charging adapter from hobbyking and cut one side

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I have silicon wire, I can get banana plugs, so what I really need are the probe ends.  Any source for those?

-Garry

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pounder
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meh I just jam 14 gauge copper wire in the terminals..it’s 14/2 cable for household wiring which I have a ton of..you just have to make a bend in the part that goes into the DMM port for it to make contact..works quite well for the price lol

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radiancez567 wrote:
ryansoh3 wrote:
What does the resistance read when you short out the two probes?

Around 80ohms inconsistent.

80 Ohms is way too much, I’m afraid. Getting thicker ones will definitely help.

My Fluke leads read 0.1 Ohms, so that is indeed an option. However, as others have stated, making your own would be cheaper and better.

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Richie086
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ryansoh3 wrote:
radiancez567 wrote:
ryansoh3 wrote:
What does the resistance read when you short out the two probes?

Around 80ohms inconsistent.

80 Ohms is way too much, I’m afraid. Getting thicker ones will definitely help.

My Fluke leads read 0.1 Ohms, so that is indeed an option. However, as others have stated, making your own would be cheaper and better.

Which Ohm setting are you guys using. On the 200 ohm setting, I get 00.3. Switching to 12 gauge leads, only gave a slight higher tail cap readings on my flashlights. So I’m assuming it isn’t bad as is, but I am in the process or getting high end banana clips and wiring for it permanently.

This is the one I’m using.

http://www.amazon.com/Equus-3300-Hands-free-Digital-Multimeter/dp/B001O1...

Richie

Werner
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It depends on which driver you have too. on a 7135 driver it has no effect just on voltage depending drivers it makes huge difference.
If you have 0.3 ohm and a direct driven light the cables will steal 1Volt and with that decrease current a lot( here is a mistake included, who finds it?)

Richie086
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Werner wrote:
It depends on which driver you have too. on a 7135 driver it has no effect just on voltage depending drivers it makes huge difference. If you have 0.3 ohm and a direct driven light the cables will steal 1Volt and with that decrease current a lot( here is a mistake included, who finds it?)

Thanks Werner. I’ll get the better components installed on my DMM for sure.

Richie

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So how would you guys rate mine?

It jumps down to 00,1 and up to 00,2 at times..
Readings show “0” on the other OHM settings.
(got my DMM for free, so no fancy stuff. Wires are upgraded, but around 1m long measured all the way out to the tips.

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whokilledJR
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I went to a local electronic shop and just bought several different replacement leads made for multimeters. One of these worked out and has given me consistent readings since. I’ve also jammed thick wires into the ports before without any modifications and it worked.

Johm
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I made these leads today with a friend.

It takes very good V and A measurements (got a steady 2.81A for a 8×7135).

John.

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Pomona is suppose to be some of the best. You can find various parts here and zorotools also has a Pomona leads and parts.
From what I have read Pomona makes leads for some fluke models.
I personally would just use some heavy 16AWG or bigger silicone wire for tail cap readings. Unless you just need some better leads.
Zorotools also has discount code 5% off $25 or more (Zmail4u)
They also have larger discounts for larger orders. Google search.

radiancez567
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Werner wrote:
Hobbyking has golden banana plugs and silicone wire these will make nice custom made cables. They also sell shrinking tube for about nothing.
AWG16 and down should make nice cables.

Mine are made from 0.2m long 1.5mm^2 super flexible wires, I tinned the ends. I also solder them direct in circuit to measure led current instead of crappy crocodile clips.

I am planning to make some thick crocodile clips myself when fasttech stocks silicone wire.

If you don’t want to make them yourself you can buy a charging adapter from hobbyking and cut one side

I think I’m going to buy the charging adapter; seems like the best with minimal DIY (just cut one end right?)

E1320
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Just cut up an old extension cord and jam them in the holes.

I am already visualizing the duct tape over your mouth.

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My DMM reads 0.03 Ohm in 200 Ohm range. Still I got much lower Amps out of one driver, it drops in the flashlights, damn bad connections add resistance.

Will make 2.5mm^2 silicone gold banana plug leads. Wire can be bought at electronics store or online, or at hobbyking probably, not sure about the quality there though.

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I just picked up a set of "Tenma" DMM leads on sake at MCM Electronics online. I'll report back on them when I get a chance to compare. I was looking for decent replacement leads, not just for tailcap current measurements. I believe "Tenma" is their "house brand". I used to deal with MCM back in the mid 90's. 

-Garry

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So I've had my new Tenma multimeter leads from MCM Electronics for about 3 weeks now.  I got them for $8.49 on sale with $5.00 shipping (I think it was a promo of flat rate $5 shipping on all orders or something) along with another set of test clip leads. They come with various thread on probes (as seen in the photo below).  The leads are 18ga and rated 2000v, and the banana plugs are stamped "1000v CAT III 16A".  They are 3.5' long and the wire feels nice and flexible.  The probe ends and banana plug ends are made of a soft comfortable flexible rubber. When I used my short homemade 12ga test leads to check the resistance of each lead I get a reading of 0.0 / 0.1ohms (display toggles between 0.0 & 0.01) when my meter is set to the "200 Ohm" setting. 

I compared some tailcap readings between two different lights using both sets of leads (my short 12ga homemade ones and these Tenma's) using the same protected Tenergy 2600mAh 18650 @ 4.21v as follows:

1) An XP-G C8 modded with a 1.4A Nanjg 3 mode driver:

Tenma leads:

Hi - 1.68A
Med - 0.52A
Low - 0.08A

12ga leads:

Hi - 1.68A
Med - 0.52A
Low - 0.08A

2) A P60 host with the famous Ultrafire 3 mode XM-L drop-in (direct drive on high):

Tenma leads:

Hi - 4.34A
Med - 1.28A
Low - 0.23A

12ga leads:

Hi - 4.80A
Med - 1.44A
Low - 0.26A

The comparison test seems reasonable to me.  I used to get much lower readings with my old meter leads.  I'd say they are acceptable and I recommend them as a cheap set. 

 

Product Photo:

1

-Garry

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FlashPilot
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Those are a nice looking set of leads Gary. Id imagine they should be good for at least 3.5A in taking reliable measurements. Thanks for posting your results.

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Number 12 AWG solid copper should read approximately 1.6 ohms per 1000’ at 20C but because of contact impedance you need to use Kelvin clips or some other four terminal method to measure this.

If you put a lead in series with a car battery and a headlight you may get a relatively constant 3A through the test lead. Then you can measure the voltage across the lead taking care that your voltmeter prods do not touch the connections that pass the current. This four terminal method cancels out the effect of contact resistance at each end.

For #12 at 3.0A with DMM test leads 2’ apart you should read 3.0 × 2 × 1.6/1000 = 9.6 mVdc. With lights in parallel you can pass more current but the test lead resistance will increase due to I squared R heating.

In any case your test lead plus ammeter shunt resistance should be at least 5x less than the circuit impedance – for a 4v, 3A light this impedance is 4/3 ohm.