Diy solderless 18650 battery kit.

[Nealh]

In post 5 I said a 50 cell kit was 900g this is wrong and is the total box weight, apparently 50 cell build adds 700g or 14g per cell, on average cells are approx. 47g each.

 

[anotherkiwi]

I am trying to figure out 4P10S in a triangle shape. 3P10S is easy...

Maybe 10 guage wires for the connection will do?

 

[anotherkiwi]

Sometime late summer after August there should be a Mk2 kit out using copper connectors which should make soldering sense wires easier.

I am going to go with the ring terminal idea from ES

 

[Nealh]

14awg silicone up to 45a.
12 up to 70a.
10 up to 120a.
12 or 1will suffice Hot-rodder.

 

[Nealh]

For soldering the sense wires I will try and replace some of the series bars with copper ones as I can get the 0.5mm copper strip I think for free, just a case of drilling the hole through. If it works then making up all the connection from copper strip may be an option.
The V2 kits will have nickel plated copper bars replacing the SS so weight should be a little less.

 

[Nealh]

Nkon also has good press. Delivery from the Netherlands to here is quite fast...
174€ for 40 GAs plus the kit plus a bit of ply and glass makes for an economical 12.6 Ah battery (90% of nominative).

The 35E is a bit cheaper, having had a good run with Samsung I may pinch pennies and stick with them.

I have read a review by Ron aka Spinningmagnets on ES
the 35E although a good high mah battery the amp rating is optimistic and is no more then a 6a cell much the same as the 29E which I have found to be not a great cell.
lygte.dk rate it as a 10a battery.

For an inexpensive build using a very good 10a cell with good mah, PF cells are well worth considering 118 euros for 40 cells.

 

[anotherkiwi]

6 Amps per cell constant discharge seems reasonable in a 5P10S battery with a 17 Amp max controller. If I am calculating correctly that is a 0.6C discharge per cell. Yes the PF cell looks OK too, Elon Musk seems cool with them

Full mAh printed on the labels are for 2 Amp laboratory load, all cells give much less when it comes to real life discharge and Ah (as those of us using Samsung 26F with a GSM or other mid-drive have discovered) than advertised.

 

[Woosh]

Would these kits not start to oxodise/corrode at the point of contact, like what we see on a car battery?

As opposed to direct welds as a means of current transfer?

I think that depends on the metal of the bolts and nuts.
If they are made of stainless steel, then no.
I think the whole pack needs to be shrink-wrapped to retain the contact pressure and reduce airflow.

 

[Nealh]

I think that depends on the metal of the bolts and nuts.
If they are made of stainless steel, then no.
I think the whole pack needs to be shrink-wrapped to retain the contact pressure and reduce airflow.

On ES the chap from India who's company is selling the kits has been answering these concerns.
R & D has been going on for 2 years in Mumbai, which he states as a hot humid part of the country he is reporting no oxidising issues. Heat shrinking is the sensible option to keep all wiring and other components safe from accidental damage also will prevent any possible 3rd party contact shorting.

Though in India looks like shrink wrap isn't on their radar .

 

[anotherkiwi]

That photo scared me too

 

[Nealh]

My kits are now in the post so hopefully should be here by the end of May, Once I start I will post construction pics as I progress. Have yet to order or decide which cells to finally get, looks like it will be either PF cells for a cheaper build or GA's for a more expensive build.

 

[anotherkiwi]

Here is a BMS for you @Nealh

https://bmsbattery.com/bmspcm/833-smart-bms-10s13s-60a-with-blue-tooth-android-or-ios-app.html

10 to 15 S so room for expansion and non more faffing about Bluetooth!

 

[KirstinS]

My kits are now in the post so hopefully should be here by the end of May, Once I start I will post construction pics as I progress. Have yet to order or decide which cells to finally get, looks like it will be either PF cells for a cheaper build or GA's for a more expensive build.

Excellent, thanks Nealh

 

[Nealh]

Here is a BMS for you @Nealh

https://bmsbattery.com/bmspcm/833-smart-bms-10s13s-60a-with-blue-tooth-android-or-ios-app.html

10 to 15 S so room for expansion and non more faffing about Bluetooth!

No use to me as I don't have a smart phone and also hate anything to techy.
Have got a 30a & 40a 10s BMS coming.
Also decide probably will ditch the S/S buzz bars for copper ones, my brothers says he got it on reels at work just like Jimmy who ordered 30k's worth.

 

[craiggor]

I paid on the 23rd April and was told there would be a delay because their machine was down. They posted on the 5th may the kit arrived today 15th April. Very quick delivery even Urvakhsha from Vruzend said that was quick for India post.

 

[Nealh]

That's 's good news Craiggor mine were also posted on the same date so could be with me this week ?
They were in the Mumbai PO on the 5th.

 

[craiggor]

My invoice was stamped 5.5.17,not sure if this was done at the Mumbai PO.No customs or taxes to pay. Delivered by Parcel Force.

Sent from my D101 using Tapatalk

 

[anotherkiwi]

About to pull the trigger on an order...

 

[Nealh]

Go for it AK .

 

[Woosh]

.

I am a bit concerned about the design of the spring (picture above).
The metal seems to be stainless steel.
I can foresee a possible issue with the formation of Chromium oxide and Nickel oxide which will introduce a resistance in the junction between cells and their busbars.