Li-ion cell interconnects and Noalox

[GregsGarage]

I have my new Li-ion cells and am not happy with the supplied interconnects.



Problem is that after a drive some are warm while others are not. Also the slot head aluminium screws are not very good. I have got a quote for making up some interconnects from flat copper braid which is a start.

I am thinking that it would be better to replace the screws with studs, but which material, copper, brass, stainless steel? Any suggestions? Suppliers?

I have also found Noalox highly recommended on american EV sites for aluminum connections to prevent corrosion. So far I have only been able to find a supplier who will sell me a case. I might go that route if anyone is also interested in using this product, I could then sell some to anyone who wants some.
http://www.idealindustries.com/products/wire_installation/accessories/noalox.jsp
Or alternatively could someone point me to a U.K. suppler of Noalox or similar product

Thanks,

Greg

[retepsnikrep]

I used 8mm threaded rod cut into 40mm-50mm lengths last time on my 30 TS 200ah cells. I needed studs and nuts to fasten interconnect with a decent amount of torque, and then fasten bms board lightly on top of that with another nut. I used spring washers as well.

The good thing about a stud is you can fit it into the terminal down to the maximum available depth which gives you the potential to torque the nut down a bit more. Resistance of interconnects is directly proportional to the torque of the bolts/nuts as well as materials etc. Nice interconnects at 10nm are much better than the same at 5nm

Do we know what the torque rating is for the terminal bolts?

Are they Aluminium?

I used the TS braided interconnects on my 200ah cells, they looked iffy but worked very well for 4 years.

Are the new interconnects Aluminium? Copper?

I have used squashed flat copper 15mm and 10mm pipe before now. Not ideal but cheap and cheerful for reasonable currents.

I would be up for a tube of that stuff

I have some TS braided interconnects with an 8mm hole if you are interested

My route to happy interconnects was.

1) Decent capacity/reasonably well made. My TS ones carried 400A.
2) Scrupulously clean terminals, studs, washers, nuts and interconnects.
3) Decent level of torque on the nuts.
4) Check for localised heating after a high power run.
5) Check tightness after first month and then at 6monthly intervals.
6) Protect terminals from the elements if possible.

I would always mount my cells inside the vehicle or in a weather proof battery box, I've seen far too many terminals with green incrustaions or signs of melting/heat etc etc

[GregsGarage]

I used 8mm threaded rod cut into 40mm-50mm lengths last time on my 30 TS 200ah cells. I needed studs and nuts to fasten interconnect with a decent amount of torque, and then fasten bms board lightly on top of that with another nut. I used spring washers as well.

Cool, I will use just normal steel threaded rod.

The good thing about a stud is you can fit it into the terminal down to the maximum available depth which gives you the potential to torque the nut down a bit more. Resistance of interconnects is directly proportional to the torque of the bolts/nuts as well as materials etc. Nice interconnects at 10nm are much better than the same at 5nm


Do we know what the torque rating is for the terminal bolts?

Are they Aluminum?

The supplied screws are aluminum, slot head and the thread length is 10mm. Take into account thickness of interconnects and washers, you are lucky to have even 8mm of thread making contact. It is not possible to tighten very much as the head of the screws round off.

I used the TS braided interconnects on my 200ah cells, they looked iffy but worked very well for 4 years.

Are the new interconnects Aluminium? Copper?

Not sure, probably tinned copper.

I have used squashed flat copper 15mm and 10mm pipe before now. Not ideal but cheap and cheerful for reasonable currents.

I am not keen on rigid interconnects in a vehicle. Vibrations might shorten cell life.

I would be up for a tube of that stuff

Chasing up some other possible leads, if anyone has a source let me know.

My route to happy interconnects was.

1) Decent capacity/reasonably well made. My TS ones carried 400A.
2) Scrupulously clean terminals, studs, washers, nuts and interconnects.
3) Decent level of torque on the nuts.
4) Check for localised heating after a high power run.
5) Check tightness after first month and then at 6monthly intervals.
6) Protect terminals from the elements if possible.

I would always mount my cells inside the vehicle or in a weather proof battery box, I've seen far too many terminals with green incrustaions or signs of melting/heat etc etc

All very good advise, Thanks Peter

Greg

[MalcolmB]

There's a short discussion here about lubrication that might be of interest
http://cr4.globalspec.com/thread/11994/ ... al-contact

[GregsGarage]

Noalox, Penetrox and other Anti-Corrosive Zinc Pastes were originally developed for the American housing market. For a while Aluminium was used as well as copper for household wiring and these pastes were to be used on the aluminium connections. If installed correctly it could be as reliable as copper, unfortunately who ever reads the instructions.

A good site can be found here; http://www.sw-em.com/anti_corrosive_paste.htm

The author prefers the thicker Penetrox, but he is using it on vintage cars. We need it for the aluminium connections at the batteries which are going to be in a waterproof battery box.

A quick search on the Internet turned up one possible U.K.supplier for Penetrox, rung them up and they had never heard of it, although they used to be affliated with the manufacture.

Wurth also do a aerosol spray to be used on new connections but it is so thin I was concerned that it could possibly seep past the posts on the cells and contaminate the insides. Maybe I am a little to paroniod, but I spent a few quid on these, so don't want to risk it.

I should get a price on a case of 4oz bottles and a case of 0.5oz tubes tomorrow. Anyone have any preference, I am leaning toward the small tubes, easier to post, unless the 4oz bottles are much cheaper relative to volume.

Greg

[GregsGarage]

If anyone is looking for some Noalox I have got some 4oz bottles now. I wanted to try the stuff out but had to by a box of 10.

PM me if you require a bottle, price is £10 + £2 P&P. As far as I am aware this is not available anywhere else in the U.K.

[Alan Ward]

To add to Peter's useful list of minimising contact resistance at TS terminals, I found the larger diameter 25mm stainless steel washers better than the smaller ones supplied by TS.

With far-from scruplous initial cleaning, the average resistance using TS braid inter-connects after 3 years is 70 micro-ohms. So at my normal 200 amp maximum I waste 14 milli-volts = 0.14 volt. (times 30 = 4 volts)

Separate query: I have only just noticed that the new 200 Ah TS cells seem to have aluminium terminals for both negative and positive. The older cells had copper negative terminals. I just wondered why. Alan

[Alan Ward]

I forgot to add that I wrote a short Letter to the Editor in the BVR for January 2006 page 29 - 30 with this 60 (now 70 ) micro-ohm figure and with the much higher figure due to my mistake:- the thin protective plastic sleeving prevented full contact area between terminal top and braid-connector. Alan

[timpootle]

I used 8mm threaded rod cut into 40mm-50mm lengths last time on my 30 TS 200ah cells. I needed studs and nuts to fasten interconnect with a decent amount of torque, and then fasten bms board lightly on top of that with another nut. I used spring washers as well.

Cool, I will use just normal steel threaded rod.

The good thing about a stud is you can fit it into the terminal down to the maximum available depth which gives you the potential to torque the nut down a bit more. Resistance of interconnects is directly proportional to the torque of the bolts/nuts as well as materials etc. Nice interconnects at 10nm are much better than the same at 5nm 8)


Do we know what the torque rating is for the terminal bolts?

Are they Aluminum?

The supplied screws are aluminum, slot head and the thread length is 10mm. Take into account thickness of interconnects and washers, you are lucky to have even 8mm of thread making contact. It is not possible to tighten very much as the head of the screws round off.

Just as a datapoint, I agree that the screws supplied by HiPower are not fit for purpose. The size on my 200Ah cells is M10, so am looking around now for suitable stainless-steel studding or grubscrews.

[retepsnikrep]

Just use M10 threaded rod cut to length, I think mine was plated not stainless, it doesnt matter.