so its initial voltage - (voltage under load/ current)?

(initial - load voltage)/(current draw)=R

I found this equation:
E=V+Ir
where E=emf or open ckt voltage
V=terminal voltage
I = current
r=int resistance
so E=V+Ir => E-V=IR +> (E-V)/I = r

so in words (open ckt voltage - terminal Voltage)/current = IR

so E is the voltage with no load?
and V is the voltage after the load or the amount of voltage lost?

The charger does that for me,the balancer was connected though but according to my last discharge records the IR was 67. It's a puffed lipo.

My charger does the IR test at 120sec into a discharge so it's different number than a E-V for a total discharge. For example this discharge with the IP5600 the IR for the total discharge(about 8.2v to 7.4v) is .11 ohm!

lol, my packs are 3-5 mOhm for the entire pack. lol, 67, seems terrible

A fully charged lipo with 4 mOhm resistance would theoretically provide 2100 Amps, mine would provide 96.55 Amps. IDK which one is more believable

I dont believe the theoretical amps and burst amps of these electronics and batteries. I dont think wire would even handle 130amp continuous and 800amp spikes.

That's why I have more faith on the number the charger spits out you know? It's like the programmer was trying to be reasonable.

That is correct, that is a rearranged version with the symbols explained differently compared to the one I put up earlier.

Its just a version of Ohm's law (V=IR). Resistance is the drop in voltage over the current that produces that voltage drop. The drop in voltage is the voltage without a load applied minus the voltage under the load that is producing the current.

May not be far off, several have reported ruined connections and/or wiring with brief dead shorts, these cells are capable of some amazing currents. Of course dead shorting shouldn't be confused with the discharge rating, which requires some load to prevent the cell and wiring from self destructing.

That would be instantaneous amps,and math says so and I believe that number. But as I said,what my charger says seems more suited for race conditions,math and science apart. I need to test a brand new lipo see what kind of numbers it gives me

Yes, IR has always been a very useful parameter to compare and track pack performance, regardless of battery type.

Different chargers and IR devices may give different readings, at times wildly different. Can't reliably compare numbers without using the same device. Also temperature is very important and impacts pack performance and measured readings, state of charge too.

I can see some value in what Wildcat is doing. But at the same time a 5 amp discharge is low. If a more real world discharge of say, 30amps +/- were used, could the results of which pack holds better voltage (under load) change..?

oh, I am well aware that 5amps is a joke. That it why I am looking ofr a PL6, lol. I can do a much bigger Regen discharge. This was more done as an example. lol. generically, IR is a pretty good indicator. if you want a quick down and dirty pack evaluation. if your charger is not up to the task, you can build a 20amp bulb discharge,r pickup a 20 turnigy watt meeter. chage the packs up and hit them with 20amp for a period of time and see which packs hold their voltage the best. I am going to pick up a light weight watt meter and mount it in my car and take some laps. I am really curious to see how much of a load my car really has.