Battery Internal Resistance Measurements

[BJ43]

Yes Dax we know....my self and others constructively engaging is this thread also have a lot of RC experience with lipo's (so your not the only RC expert here)....a long with safe use of IMR high drain and lipo's used in e-cig mods (not really interested in any of the garbage cells like trustfires and similar).

But if you took the time to look at the link.....In the picture each saddle pack cell says 7.4v and the description says 2S3P....which neither is accurate.

I understand there is some language things going on, so I'm politely asking you to either engage in this thread constructively or move on.

LOL, Built my first RC airplane in 1956, the receiver was a tube radio.

 

[bapgood]

Yeah I think they fubared the description. They say "2S3P / 2 Cell / 7.4V (Each)" which doesn't make sense by itself....then show a series plug to be used

Spec.
Capacity: 5600mAh
Voltage: 2S3P / 2 Cell / 7.4V (Each)
Discharge: 65C Constant / 130C Burst
Weight: 132g (Each)
Dimensions: 69x46x25mm (Each)

It is thicker....so probably 3 parallel cells in each pack....getting rusty on my chinglish

 

[DaxFX]

Yes Dax we know....my self and others constructively engaging is this thread also have a lot of RC experience with lipo's (so your not the only RC expert here)....a long with safe use of IMR high drain and lipo's used in e-cig mods (not really interested in any of the garbage cells like trustfires and similar).

But if you took the time to look at the link.....In the picture each saddle pack cell says 7.4v and the description says 2S3P....which neither is accurate.

I understand there is some language things going on, so I'm politely asking you to either engage in this thread constructively or move on.

I dont see anyone explaining what means 2s3p, i just posted to other non rc guys reading this knows what means, you dont need to be rude, if you don like my post no one force you to red it,

So 2s3p means 2 sets of 3 cells in paralel each set, so each set of 3 cells are 4,2v so both sets combined in serie are 7.4v nominal 8.4v peak





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[BJ43]

It is thicker....so probably 3 parallel cells in each pack....getting rusty on my chinglish

Yep, I saw that thickness and figured but that would make them each 3,7v and both packs in series 7.4v.

 

[bapgood]

I dont see anyone explaining what means 2s3p, i just posted to other non rc guys reading this knows what means, you dont need to be rude, if you don like my post no one force you to red it,

So 2s3p means 2 sets of 3 cells in paralel each set, so each set of 3 cells are 4,2v so both sets combined in serie are 7.4v nominal 8.4v peak




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I understand 2S3P

To me the "each" in the description indicates each pack is 2S3P.....Then each pack indicates 7.4v.....Then they show a series connector.

It's just a typical China description.

 

[BJ43]

I understand 2S3P

To me the "each" in the description indicates each pack is 2S3P.....Then each pack indicates 7.4v.....Then they show a series connector.

It's just a typical China description.

Yep and each pack says 7.4v on it. should be 2S2(3P) and each pack marked 3.7v

 

[Visus]

woot thread fight

ROUND

 

[bapgood]

No thread fight....I think we are all squared away.

 

[Visus]

No thread fight....I think we are all squared away.

But I have round 3 girl, I already paid her, yall gotta lol...
Ok fine white towel, ill be in the backroom




Back to good ir batts Lg up in que

 

[bapgood]

I think the keystone SMT battery holders pass the resistance test





No holder




Fasttech battery holder







Mamu wondered about the keystone battery contacts she used, so I got some and tested them. The same battery with the keystone C contact was 28mΩ and the D contact was 38mΩ. I was kind of surprised there was any difference between the two, but the springs are a little different.

I also got the thru hole version of the battery holders, and they have silver colored contacts and higher resistance, along with small thru hole pin protruding vertically from the back of the holder.








1042 Keystone Electronics | Mouser

1048 Keystone Electronics | Mouser

5241 Keystone Electronics | Mouser

5251 Keystone Electronics | Mouser

 

[mamu]

Huge huge difference with the Keystone holder vs the fasttech holder. Proves that choosing low contact resistance batt contacts is important.

Thanks for testing this, bap!!

 

[rolf]

run into a problem ..
after I dropped my mod ...nt working at all
putting in a new dna 20 wont fire at all so I measured the voltage 0.8 v !!!
so no charging this one. tried another set [ nanotech 1200 ..both ] 4.1 and works fine.
so something must have slowly drained the batterys before I got back to change the dna board.
it was standing for a while with the board and also the charger board in it .
the charger board was not connected through the dna 20.it was direct to the batterys over a fuse
anybody has any idea what coused the drain ..and even more important what will prevent that ?

 

[mikepetro]

BJ, now that I am realizing the importance of a few milliohms, what would be the odds of getting you to run a few resistance tests for me?

I am trying to think of a quick disconnect for the battery for the "Beta tester" Mod I am planning. Naturally anything in that input circuit would add to the resistance and I am trying to understand the magnitude of a quick disconnect. I want to be able to swap various bats in and out to test performance. Cylinder bats would be easy with a bat holder, but LiPos present more of a challenge.

Could you measure:

• A soldered connection
• A dupont pin soldered to a board mated with a crimped dupont connector
• A "Sta-Kon" male/female crimped connection
• A 4mm banna conector like on many of the LiPo bats.

I promise, next time I order from HobbyKing I will get one of those meters of my own.

 

[bapgood]

BJ, now that I am realizing the importance of a few milliohms, what would be the odds of getting you to run a few resistance tests for me?

I am trying to think of a quick disconnect for the battery for the "Beta tester" Mod I am planning. Naturally anything in that input circuit would add to the resistance and I am trying to understand the magnitude of a quick disconnect. I want to be able to swap various bats in and out to test performance. Cylinder bats would be easy with a bat holder, but LiPos present more of a challenge.

Could you measure:

• A soldered connection
• A dupont pin soldered to a board mated with a crimped dupont connector
• A "Sta-Kon" male/female crimped connection
• A 4mm banna conector like on many of the LiPo bats.

I promise, next time I order from HobbyKing I will get one of those meters of my own.

IMO the best bet for a lipo is going to be good quality gold plated bullet connectors.

 

[BJ43]

BJ, now that I am realizing the importance of a few milliohms, what would be the odds of getting you to run a few resistance tests for me?

I am trying to think of a quick disconnect for the battery for the "Beta tester" Mod I am planning. Naturally anything in that input circuit would add to the resistance and I am trying to understand the magnitude of a quick disconnect. I want to be able to swap various bats in and out to test performance. Cylinder bats would be easy with a bat holder, but LiPos present more of a challenge.

Could you measure:

• A soldered connection
• A dupont pin soldered to a board mated with a crimped dupont connector
• A "Sta-Kon" male/female crimped connection
• A 4mm banna conector like on many of the LiPo bats.

I promise, next time I order from HobbyKing I will get one of those meters of my own.

Me thinks you vaped to much hemp. I no have that meter.. Mr Bap has the resistance meter, I have the ECD....

 

[BJ43]

I was curious about my very low imput voltage drop on my Raptor with the 4200mAh A Spec. Only .04v drop while mamu was getting .2 to.4 with the Lg 18650. So I tried several older 7.4 packs I had laying around. A couple of Zippys and other Lipoly all over 5000mAh 25 to 40C. On all I got between .08 to .2 imput drop with output a 5v on a 1.3 ohm coil. I can state for sure, the higher C rating the lower the imput drop. None beat the 65C 4200mAh at only .04v drop. The 25C gave .2v drop, the 30C .15v, and the 40C .08v..

 

[BJ43]

IMO the best bet for a lipo is going to be good quality gold plated bullet connectors.

Ditto.....RCers really work at getting the best connection possible and those are the preferred..

 

[mikepetro]

Me thinks you vaped to much hemp. I no have that meter.. Mr Bap has the resistance meter, I have the ECD....

Who.....ME?

 

[mikepetro]

I was curious about my very low imput voltage drop on my Raptor with the 4200mAh A Spec. Only .04v drop while mamu was getting .2 to.4 with the Lg 18650. So I tried several older 7.4 packs I had laying around. A couple of Zippys and other Lipoly all over 5000mAh 25 to 40C. On all I got between .08 to .2 imput drop with output a 5v on a 1.3 ohm coil. I can state for sure, the higher C rating the lower the imput drop. None beat the 65C 4200mAh at only .04v drop. The 25C gave .2v drop, the 30C .15v, and the 40C .08v..

Interesting. So is it safe to surmise that the higher the C rating the lower the internal resistance of the bat?

 

[bapgood]

Interesting. So is it safe to surmise that the higher the C rating the lower the internal resistance of the bat?

Some will say no....and they might be right in some regard. But everything I have tested the higher the C or amp rating the lower the IR is.