$1 a spring still sounds ok to me, I’d take a handful.

Thanks you all for the replies, and special thanks to Hank for the elaborate explanation of the testing of the intl-outdoor spring.

I think you are right, I was a bit too negative about them, they sure have their purpose because they are a noticable upgrade for stock steel springs. I really hoped that they would be as good as a copper braided spring, but springs just do not get much better than this. The resistance is not as low as the intl-outdoor spring but much better than steel springs, and the mechanical properties are excellent.

Thinking about these alloys, (I looked it up) phosfor bronze has a conductivity of 10-20% IACS, beryllium-copper is also 10-20%IACS (all depending on the precise alloy). The intl-outdoor beryllium-copper alloy has an exceptional 45%IACS, but at some expense of the mechanical properties. So I think that the elusive beryllium-copper spring that has been the talk of BLF for a while will either be electrically not much better than my phosfor-bronze spring, or mechanically worse to some extend.

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 some…

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 6A… now I’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 “just”, ordered em a couple of weeks ago, expecting them any day now)

Your phosphor bronze spring looks like a good one, I wouldn’t mind picking some of those up from you if you are wanting to recoup some of that test budget. :wink:

While I don’t mind soldering the 22ga wire inside a spring, I don’t like the steel springs that the solder might not stick to… releasing the bypass without my knowledge or being a “cold joint” that isn’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 wouldn’t be mandatory to do the bypass.

Nice test, finally able to “see” what’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 won’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 that’s a good idea DBC. So coil it up and it’ll act with the spring. Thanks I’ll start doing that :slight_smile:

You don’t want too much or it’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 I’ve done similar test (for current 3A) and I must tell that Your test doesn’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:


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