Springs!!

Nice work seems like this hobby is getting expensive.

Thanks Djozz for your invaluable test!

love you work and dedication!

Thanks for another very valueable test.

The becu spring is better than I thought, I have to order someā€¦

Djozz, you da man! :)

I had hoped the nanjg105c spring was better. But now I know how that compares to the others.

Thanks for all this data!

Yeah, braiding the Nanjg 105c spring should free up ~0.068v at 6Aā€¦ now Iā€™ve just got to figure out the best way to braid/wire such a small spring. I think my normal technique involves too much solder wicking up in the copper. The spring is only what, 5mm tall?

Thanks, once again, for a job well done!

And timely too! I just ordered some of those beryllium copper springs from Hank! :slight_smile: (I say ā€œjustā€, ordered em a couple of weeks ago, expecting them any day now)

Your phosphor bronze spring looks like a good one, I wouldnā€™t mind picking some of those up from you if you are wanting to recoup some of that test budget. :wink:

While I donā€™t mind soldering the 22ga wire inside a spring, I donā€™t like the steel springs that the solder might not stick toā€¦ releasing the bypass without my knowledge or being a ā€œcold jointā€ that isnā€™t producing the required result. So the phosphor bronze spring would be an excellent answer, taking solder and already having a low resistance such that it wouldnā€™t be mandatory to do the bypass.

Nice test, finally able to ā€œseeā€ whatā€™s going on there!

Did the drill a hole through the board mod the other day. So a wire went right to the driver. Anyone have thoughts on the best copper braid to use? This cheap stuff I got probably wonā€™t hold up. Pick up some of those copper springs too- have to order some stuff today.

fell, I use the same 22ga wire that I use for the leads to bypass the springs. Soldering it at the pad first, I try to put a slight coil to it before soldering it on top of the spring, this way it compresses inside the spring and should last indefinitely.

Ooo thatā€™s a good idea DBC. So coil it up and itā€™ll act with the spring. Thanks Iā€™ll start doing that :slight_smile:

You donā€™t want too much or itā€™ll clog the spring action.

Djozz, very interesting measurements :slight_smile: ~0,3V voltage drop for 6A current makes such spring a nice heater :bigsmile: Some time ago Iā€™ve done similar test (for current 3A) and I must tell that Your test doesnā€™t include one, but very important parameter (surface of electric contact to battery cells terminal). It will be different for every spring (hard to calculate) but also generating voltage losses.

Thank you again djozz for your contribution to this community. :beer:

Thx djozz,

that is very very useful testing. :beer:
I will braid even more springs from now on.

What we need is a spring that is composed of a spring steel core with a pure copper outer layer. And the copper layer needs to be more than just a coating. It needs to have some thickness to it. :smiley:

TY :-)

great test djozz! :beer:

(againā€¦)

Yes, I think surface area matters. Usually when braiding, I fill the top of the spring with solder then file flat.

very nice test, thanks for posting this

What I usually assume is that although the contact surface area may be very small, the resitance is also determined by the length of the narrow section. With two flat surfaces touching, that length is so short that the resistance is still negligible. If one surface is bended (the spring) the resistance may be a bit higher but still very low. Bocian, is there any measured data on this contact resistance? (there must be somewhere).

Thanks for the Test! I think steel springs are the best, gold plated or just simply plated. With the braid, (copper or the silver plated stuff), the spring can then be just what it is, a spring and the current will go through the braid. It will also help with heat stress on the spring, so a little longer life span for the spring. Excessive heat really kills those little springs. When you solder the braid on, you can always solder a copper button on top too, for a good smooth contact to the battery.