Eastwood’s first battery build

[harrisonpatm]

So what would be an example of cells that are not evenly matched when it comes to milliohms? Trying to learn for future battery builds of what would not be excepted.

You could balance each P-group to be equivalent cumulative IR.

The spec on those cells on one spec sheet I found has IR @ 10milliohms. If they all tested between 9.02-9.5, I wouldn't worry too hard about them being IR matched.

 

[999zip999]

I thought they had two capacitors they also have 11 cells ? What exact cells are in there ? Size brand ?
Plus how much did you pay ?

 

[Eastwood]

I thought they had two capacitors they also have 11 cells ? What exact cells are in there ? Size brand ?
Plus how much did you pay ?

No cells just the 2 capacitors in the spot welder.
Got a good deal because of Amazon prime day. The price is normally $300 but paid $225
Then the 4 year extended warranty was $45 I believe.

Will do some test spot welds soon as I just finished working on my forks for the Rmz conversion.

 

[999zip999]

Then where does the talk of the internal resistance on 11 cells come from ?

 

[Eastwood]

Then where does the talk of the internal resistance on 11 cells come from ?

Oh, I was testing the Molicel 21700 p42a cells. My battery pack will be “11p” 28s.. So yesterday I tested all 308 cells.

Used this model to check the resistance

Amazon.com

 

[amberwolf]

So what would be an example of cells that are not evenly matched when it comes to milliohms? Trying to learn for future battery builds of what would not be excepted.

I don't have any links to specific posts ATM.

To see what cells can look like (good and bad) you can look at things like Pajda's (and others') testing threads, and testing sites like lygte-info.dk where there are comparisons, etc.

Just an example: 9.25 then maybe 10.25 milliohms something that far apart?

I think that would be pretty far apart for new cells; would usually indicate they aren't from the same batch or are "lower grade" cells that are less likely to match in characteristics.

Some of the stuff reported here is tens or dozens of milliohms different for high resistance cells; IIRC these were salvaged cells, so not the same kind of case as yours.

Proportionally, some of the worst cases reported with "new" cells have been two or three hundred percent difference between cells, which is absolutely awful.


The resistance works just like in ohm's law, so the greater the resistance, the greater the voltage sag during discharge, and the higher the voltage rise during charge. This is where imbalances begin, as the difference in voltage.

When the resistance is different then other cell characteristics are probably also different.

Cell characteristics typically only get more different over time, so....

 

[Eastwood]

Thinking about going with this BMS, 380a continuous and 950 peak. Its a new release from ANT BMS, like the fact you can bolt the connectors to the terminals. Since this is 380 continuous, I won’t need to bypass the BMS on the discharge. They also came out with a new 2.4 inch display for the BMS.

Thoughts on ANT BMS?

https://a.aliexpress.com/_mrDW56E

 

[999zip999]

I couldn't find a link for that BMS do you have one ?
I like a screen that shows all the cells at once I don't want to have to scroll from 1 to 30 cells to fine their voltage

 

[amberwolf]

I couldn't find a link for that BMS do you have one ?

It's in his post between the pictures.

 

[j bjork]

I dont think it is very important to see all voltages at once, I normally just look at high, low and avarage. When they are 1-3mV from each other I know all the voltages are alright.
I think ant seems decent, but I havnt tried the others.

 

[999zip999]

Sorry I didn't see it . They have a 4.3 inch screen. That is still pretty cheap.

 

[Eastwood]

Well looks like can’t use the display with over 24s battery
Was thinking I could just connect to the 12 V power supply but then the minimum voltage is 24.

 

[Eastwood]

I mainly just need a voltage display, was considering this one since it’s so small and then I can actually see the different cell groups as well.

My voltage display now is connected with my throttle, but I don’t think the display is going to work with my 28S battery.

 

[Eastwood]

So here’s a technical question

So typically I use tinned copper, marine grade wire for discharge wires and phase wires, But this got me thinking, that maybe pure copper wire would offer less resistance. How much resistance is added with the copper wire being tinned?

I’m not sure of how much of a difference this would make versus using non tinned copper wire. My goal is to have less resistance as possible so I’m thinking of maybe using pure copper wire. Thoughts?
I understand the non tinned copper wire is more vulnerable to corrosion, but also considering my busbars are pure copper with no protective coating.

Here’s the two options I’m looking at, both 4/0 AWG.

4/0 AWG Marine Wire - Tinned Copper Boat Cable- Amazon.com

Spartan Power Welding 4/0 AWG, Amazon.com

 

[harrisonpatm]

So here’s a technical question

So typically I use tinned copper, marine grade wire for discharge wires and phase wires, But this got me thinking, that maybe pure copper wire would offer less resistance. How much resistance is added with the copper wire being tinned?

I’m not sure of how much of a difference this would make versus using non tinned copper wire. My goal is to have less resistance as possible so I’m thinking of maybe using pure copper wire. Thoughts?
I understand the non tinned copper wire is more vulnerable to corrosion, but also considering my busbars are pure copper with no protective coating.

Here’s the two options I’m looking at, both 4/0 AWG.

4/0 AWG Marine Wire - Tinned Copper Boat Cable- Amazon.com

Spartan Power Welding 4/0 AWG, Amazon.com

You're crimping lugs onto the wire, aren't you? I use pure copper cabling, with a crimped lug, and vinyl tape and/or shrinkwrap over the lug. So none of the copper cabling will be exposed to the elements, if done properly. Then dielectric grease on the lug, where it bolts into the next connection (controller, fuse, shunt, whatever you end up doing). So i get the electrical properties of pure copper, and where it's exposed, I use the dielectric grease. Tinned copper won't corrode, sure, but I don't really see that as a problem if you just make it part of you maintenance checks.

An argument can be made for using tinned copper lugs instead of bare copper, but I don't really see the benefit to having the actual cabling tinned. When you strip the cable ends to make you connections, just make sure that gets taped, wrapped, or treated properly to make it weather resistant.

 

[999zip999]

It depends where you live you live by the ocean and you ride on the beach we will turn green the copper that is and where the copper connects with electricity. Green.
So dielectric grease is a necessity.

 

[Eastwood]

You're crimping lugs onto the wire, aren't you?

Yes crimping lugs and will use marine grade heat shrink.
Yeah, I’ll probably end up going with just the pure copper wire, non tinned. The reason I use tinned wire in the past with hub motors, is that’s typically how moisture wicks inside the motor is through the strands of wires when going from hot to cool. Not so much water getting on the end of the terminals, but more so from moisture being in the air.

But Yeah, I was just curious of how tinned copper wire can increase resistance. I’m sure it’s minimum but it’s something.

It depends where you live you live by the ocean and you ride on the beach we will turn green the copper that is and where the copper connects with electricity. Green.
So dielectric grease is a necessity.

No beach riding with this build, but definitely lots moisture from the muddy trails in my state. I’m thinking non-tinned copper wire, with tinned lugs.

 

[gobi]

Eastwood,

1. No nickel plated wire will not increase resistance
2. 4/0 wire, one word OUCH, I use 4/0, I use all ANCOR Marine wire. But they are VERY difficult to bend etc. I will send you a PM.
3. Corrosion - for water (no salt) and other crap, I asked the same and was told Ox-GARD (not De-Ox) (lowes) is the best thing, you apply some on the wire strands BEFORE crimping, wipe off the excess after crimping and coat the lug and wires edge with a thin film and them apply marine grade heat shrink, 2 layers, 2nd layer being longer than the first to seal.
4. Crimping 4/0 - my little crimper will not do 4/0, that required a bigger one
5. Battery cable - fine strand battery cable is good too, they also come in 4/0, I would use multiple 1/0 to navigate bends better it that is a bottle neck.

 

[MorbidlyObeseKoala]

On the topic of battery wiring:

I think I have asked this before but did not get a response I was expecting. Is there a measure-able difference between some standard stranded wire and "oxygen-free" copper wire? Someone mentioned it in a battery building Facebook group and I had never heard of it before. Apparently the car stereo/audiophile people use it a lot and that is supposedly the lowest resistance stuff you can get.

I don't know if that is a marketing thing or some certification of copper purity or what but it was new terminology to me and I have yet to find another person to seek that out for battery building specifically. If anyone has some sources to share where one would determine what level of power it would matter, that would be really interesting to read.

Sorry for the slight derailment here...

 

[amberwolf]

If it's helpful, a quick google on your phrase "Is there a measure-able difference between some standard stranded wire and "oxygen-free" copper wire?" finds this page as the first hit

https://gearspace.com/board/connectors-cables-stands-and-accessories/1083712-there-noticeable-sonic-difference-between-cables-5.html

that quotes this page

Speaker Wire

that appears to give some detailed info. I don't know enough to know if the info is correct, but the relevant section is quoted below:

*********************************************************************************************

What about “oxygen free” wire?​

Oxygen-free copper (OFC) or Oxygen-free high thermal conductivity (OFHC) copper generally refer to a group of wrought high conductivity copper alloys that have been electrolytically refined to reduce the level of oxygen to .001% or below. Perhaps, it should be more accurately called oxygen reduced copper.

C11000 is the most common copper. It is universal for electrical applications. Electrolytic-Tough-Pitch (ETP) has a minimum conductivity rating of 100% IACS and is required to be 99.9% pure. It has 0.02% to 0.04% oxygen content (typical). Most C11000 sold today will meet or exceed the 101% IACS specification. For the purposes of purity percentage, silver (Ag) content is counted as copper (Cu).

C 10200 is known as Oxygen-Free (OF). Its conductivity rating is no better than the more common C11000 grade mentioned above. However, it has a 0.001% oxygen content, 99.95% purity and minimum 100% IACS conductivity. For the purposes of purity percentage, silver (Ag) content is counted as copper (Cu).

C10100 is known as Oxygen-Free Electronic (OFE). This is a 99.99% pure copper with 0.0005% oxygen content. It achieves a minimum 101% IACS conductivity rating. Silver (Ag) here is considered an impurity in the OFE chemical specification. This copper is finished to a final form in a carefully regulated, oxygen-free environment. It is also the most expensive of the three grades.

Many owners of high-end audio and video equipment value “oxygen free” copper. Behind this demand is the belief that it will have enhanced conductivity or other electrical properties that are significantly advantageous to audio signal transmission. However, as indicated above, most C11000 common copper sold today meets or exceeds the 101% IACS conductivity and overlaps C10200 “oxygen free” that has a minimum of 100% IACS conductivity. In practice, there is no significant difference in conductivity between all three of the grades as far as audio use is concerned. It can be considered to be ordinary copper wire as far as the recommended lengths of copper wire in the table. However, for industrial use, C10100 OFE copper is valued for purity and used for such applications as plasma deposition, semiconductor manufacture and particle accelerators.

 

[Eastwood]

Eastwood,

1. No nickel plated wire will not increase resistance

Well, I would think it would add some resistance, but it’s probably splitting hairs you know.

2. 4/0 wire, one word OUCH, I use 4/0, I use all ANCOR Marine wire. But they are VERY difficult to bend etc. I will send you a PM.

Replied!

3. Corrosion - for water (no salt) and other crap, I asked the same and was told Ox-GARD (not De-Ox) (lowes) is the best thing,

Interesting! First time hearing of this stuff.

4. Crimping 4/0 - my little crimper will not do 4/0, that required a bigger one

Yeah, I’m looking at some cheap crimpers on Amazon around the $60 range. I found some videos where they cut open the lugs to see how solid of a connection with these cheap crimpers and they looked pretty dang solid.

5. Battery cable - fine strand battery cable is good too, they also come in 4/0, I would use multiple 1/0 to navigate bends better it that is a bottle neck.

I shouldn’t have to bend the discharge wires too much because of the configuration. Just bolting the lugs to the controller should be the only major bend.

 

[harrisonpatm]

Yeah, I’m looking at some cheap crimpers on Amazon around the $60 range. I found some videos where they cut open the lugs to see how solid of a connection with these cheap crimpers and they looked pretty dang solid.

Have you seen/considered a hammer crimp? I love mine. $15-20 bucks, huge range of lugs it can crimp, simple mechanism that's unlikely to break or wear out. Downsides are that it has to be fixed to a workbench or table (have to bring the cable to the crimper, instead of bringing the crimper to wherever you're working), and you have to hit it really hard with a large hammer to get a good crimp. Upside is that you get to hit something really hard with a large hammer!

 

[Eastwood]

Have you seen/considered a hammer crimp? I love mine. $15-20 bucks, huge range of lugs it can crimp, simple mechanism that's unlikely to break or wear out. Downsides are that it has to be fixed to a workbench or table (have to bring the cable to the crimper, instead of bringing the crimper to wherever you're working), and you have to hit it really hard with a large hammer to get a good crimp. Upside is that you get to hit something really hard with a large hammer!

Yeah, I’ve considered those Hammer crimps in the past with smaller gauge wire. Probably will end up ordering this unit.

12 Ton Hydraulic Crimping Tool 8AWG to 4/0AWG) https://a.co/d/1obYRgC

 

[gobi]

FYI:
dielectric grease is NOT conductive, there is a whole list of stuff that prevents corrosion and their conductive properties.
Yeah, I was shocked too. If the amps are not too large, I just use synthetic marine grease, like my outside a/c plugs for my roof ice damp heating.
The main problem with stranded wire and a connector is the front open part and wicking effect, over time you can bet the wire strand will be saturated with what ever is coming at them.
you want nickel plated stuff when any moisture is present.

 

[999zip999]

Talking about wicking moisture after you crimp your 4/0 wire into a lug wouldn't you solder the copper wire ends at the end that points out the end of the lug so moisture doesn't weep in ?
Plus how's that new spot welder of yours working. What do you find most useful the two pens the one handed handle or it looks like you put the machine on its end and plug in the lever activated spot welder attachment.
I was hoping just to get away with the handheld pens but I'm doing 120 cells so. ? Thanks