Question for you Turbo 35 (or 30) owners

[Leet TC3]

I have a CE Turbo 35 battery charger.

My question is in regard to the IR (Internal Restistance) rating. I just purchased several new packs, all of them 2400 Nicad Trinity Team. I am getting IR's in the 40's and 50's, even though the IR rating on the battery label is the the mid 20's. The same goes for other parameters (avg. voltage, etc.). They are not as good as the label ratings.

These ratings were all done on a CE matcher, so they should be the same readings on the charger.

Is this because these ratings from Trinity are based on a single cell, and that all the soldering and assembling, etc all build up the IR for the pack as a whole? (I use Deans btw) What readings do you all get on a Turbo 35?

These batts are all new so I expect the IR to go down after several flex-charge cycles, but I don't know if they will ever get to the mid 20's.

Also - I have packs assembled in stick and side-by-side configurations. I notice that the side-by-sides always have a better IR, avg voltage etc. than the sticks. I assume this is because sticks are spot welded together, whereas the side-by-sides are all soldered. Have you all noticed this too?

[SirSpeedy]

Are you talking about Actual IR, or Relative IR? Trinity use Relative IR, which will yeild values from 15-40 or so. Actual IR is an actual measurement, in milliohms, and that is usually around 2.5-4.0mohms.

If the packs are soldered up correctly, the IR should be similar. If you say your cells are labeled in the 20's, well lets say they were all 25, you would get an actual IR for the pack of 150 for a six cell pack.

Let me know if you need any help. I match cells all the time.

[Leet TC3]

I was referring to actual IR.

But even using the relative IR as measured by Turbo 35, the numbers are still higher than what is listed on each cell. e.g. I get a relative IR of 215 mOHM from the pack, which divided by 6 would be about 36. The individual cells are each around 22-25.

We are talking about very slight differences, I know. But I am curious as to where the added resistance comes from. The measurements on the battery are for each individual battery. No matter how great the soldering job is, there HAS to be some added resistance. Perhaps when soldering 6 together, plus the plugs, make up the difference?

[nsane]

No doubt that everything else involved is having an impact. The plugs are probably having some impact as well; don't forget, when they number those cells they are single with very little external resistance.

I'd say your assessment is probably accurate.

[SirSpeedy]

Something else is up.

My 24's are like 3-3.5mohms per cell, and the packs cycle right on the money. 20-22per pack. Unless you have done a really bad job of soldering them.

What plugs are you talking about? On the T35? They have no bearing on the measurement, as the small voltage sensing leads are soldered directly to the board inside. You are using the voltage sensing wires?

How many cycles do they have on them? You said they are new, How new?

Let me know...

[Leet TC3]

Oh... So THAT's what those little leads from the Turbo 35 are for! :D

Actually, I knew they were voltmeter leads, but I never saw the point of connecting them for battery cycling. Then I read the manual (I know... RTFM...), and even though CE's manuals are a little superficial, they DID in fact recommend connecting the voltmeter leads for any discharging.

So... the numbers for Team 2400's are much more in line:

.........LABEL.......ACTUAL
Rel IR...23-25.......25.8
MaHR.....2433........2405(chg)2243(dischg)
MwHR.....2707........2535
Avg Vlt..6.68........6.78

(btw, what is the MaHR rating on labels? Is it the charged capacity or the discharge value?)

These batteries are on their 8th or so cycle. I charged them at 4.5 amps and discharged them down to 5.4v at 25 amps, loopback voltage set at .05. Trinity tests them at 4.0 amps charged, discharging to 5.1v at 30 amps with .02 loopback voltage.

All Trinity numbers are on a single cell. This, plus my slightly different charge/discharge cycle setup could explain the slight differences in the numbers above. I will cycle them using Trinity profiles to see if they get closer.

One question: I have stick and side by side packs. Attaching the voltmeter leads to a side by side pack is easy, but what about the stick packs? How would you go about it?

I have replaced the larger aligator clips on the Turbo 35 with Dean's ultra plugs. The only way that I can figure to attach the voltmeter leads to sitck packs would be to leave a slight gap in the Dean plug between the charger and the battery pack (the clips on voltmeter leads are quite small).

Or... I could kludge together a cable that would allow me to charge batteries using aligator clips, but that leaves open the possibility of the the two leads inadvertantly coming into contact with each other, with the resultant fireworks display.

[ 06-16-2001: Message edited by: Leet TC3 ]

[ 06-16-2001: Message edited by: Leet TC3 ]