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Old 07-31-2014, 01:22 PM   #16
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No charger or IR device is true.. They all state THE IR is estimated..
The only true way is to apply OHM's law..
Build a light dis-charger..I have 3 or different amperage's from 5 amp draw to 50 amp draw
also needed is a Good watt meter and a pad of paper to write down your results..
These things can be done for under $40 if you shop around..
$6 at local dollar store for car lights
a couple of connectors.$5
wire $2
watts meter $25 Tops -got mine for $15 wattsup
no need to buy a IR meter that states all IR measurements are estimated when you can have Non estimated results and #'s

a Good IR measurement is anything under 15 milla ohms per cell
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Old 07-31-2014, 01:32 PM   #17
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Even if chargers are estimating the pack IR or is displaying IR which is incorrect. Isn't it still a satisfactory way of at least comparing packs on the same charger to see which of your packs has the lowest IR and therefore better punch?
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Old 07-31-2014, 01:37 PM   #18
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for you sure... for me NO.. I deal in truths and as you are well aware of this hobby does not allow that to be it is full of junk and worse..don't wanta violate any rules on this forum by saying THE TRUTH.. I see what happens to people who don't go with the majority they get the giant boot so the liars can run free

This is how I see things We have battery's that can put out 200 amps easy and that amount of power can hurt or kill a person if there face is in wrong place or any other vital thing can of gas
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Old 07-31-2014, 02:09 PM   #19
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Originally Posted by ElectricMann View Post
for you sure... for me NO.. I deal in truths and as you are well aware of this hobby does not allow that to be it is full of junk and worse..don't wanta violate any rules on this forum by saying THE TRUTH.. I see what happens to people who don't go with the majority they get the giant boot so the liars can run free

This is how I see things We have battery's that can put out 200 amps easy and that amount of power can hurt or kill a person if there face is in wrong place or any other vital thing can of gas
care to back that statement up?
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Old 07-31-2014, 02:12 PM   #20
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As far as IR readings, I use my Hyperion to gauge the condition of my packs through their life cycle as well as pack to pack comparisons. It's impossible to compare the IR numbers from charger to charger, even of the same brand.
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Old 07-31-2014, 03:53 PM   #21
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Originally Posted by ElectricMann View Post
No charger or IR device is true.. They all state THE IR is estimated..
The only true way is to apply OHM's law..
Build a light dis-charger..I have 3 or different amperage's from 5 amp draw to 50 amp draw
also needed is a Good watt meter and a pad of paper to write down your results..
These things can be done for under $40 if you shop around..
$6 at local dollar store for car lights
a couple of connectors.$5
wire $2
watts meter $25 Tops -got mine for $15 wattsup
no need to buy a IR meter that states all IR measurements are estimated when you can have Non estimated results and #'s

a Good IR measurement is anything under 15 milla ohms per cell
The problem with light bulbs is that their resistance varies with temperature just like everything else, but electronic circuits aren't quite so susceptible to it. Also, you are measuring all the joints in your lightbulb discharger as well as the bulbs themselves, so you are not getting the most accurate reading.
When they state estimates on meters and chargers, they aren't saying they are wildly inaccurate just not 100%.

If I had a pack that was 15milliohms per cell I'd be using it as a doorstop, I have thrown worse than that out.
I have a pack that measures (on my ESR meter) 7-10milliohms per cell and packs that have 2-3millohms per cell.
I can tell the difference on the track with the amount of punch.
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Old 07-31-2014, 05:09 PM   #22
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What is a good internal resistance for a Lipo in good condition?

Ive got three packs with varying resistance but not sure if they are getting old or faulty.

Pack 1 Orion 7.4v 5000 90c 9.8 m ohms
Pack 2 Orion 7.4v 5000 90c 11.1 m ohms
Pack 3 LRP 7.4v 7200 100c 3.7 m ohms

All these reading are taking form the LRP touch charger.

Also i'm wanting to get new lipo packs, instead of looking at the "c" rating are you better comparing the wattage of the packs?

Cheers Mike

Your results appear to be in the ball park of what I would expect for those cells.

Although perfectly accuracy would be great I doubt any device including the icharger is. Trying to measure IR under 10 mohm with a cost effective device accurately is not easy.

I would suggest you can take comparative results with your charger use the results to monitor the condition of the packs. ie when a pack is new at 50 cycles, 100 cycles 200 cycles ect.
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Old 07-31-2014, 05:16 PM   #23
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Originally Posted by Skiddins View Post
The problem with light bulbs is that their resistance varies with temperature just like everything else, but electronic circuits aren't quite so susceptible to it. Also, you are measuring all the joints in your lightbulb discharger as well as the bulbs themselves, so you are not getting the most accurate reading.
When they state estimates on meters and chargers, they aren't saying they are wildly inaccurate just not 100%.

If I had a pack that was 15milliohms per cell I'd be using it as a doorstop, I have thrown worse than that out.
I have a pack that measures (on my ESR meter) 7-10milliohms per cell and packs that have 2-3millohms per cell.
I can tell the difference on the track with the amount of punch.

Dead right skiddins.

Measuring the IR of a battery is not so simple.

Electricmann

You need accurate measurement of voltage and current whilst also taking into account voltage drop due to the change in capacity.

Light bulbs and a watt meter be unlikely to be accurate enough for meaningful results.

I think some IR measurements are made with an estimation of battery capacity hence the statement of estimated IR.

Some dischargers will estimate the capacity of the battery by discharging for 60 seconds before taking an IR measurement. The first 60 seconds of discharge provides enough information for a very accurate estimation of battery capacity.

Some chargers whilst charging may do the same before taking the IR measurement.
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Old 07-31-2014, 05:30 PM   #24
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Wayne Giles himself has said this in a few posts...

sorry but as long as you record amperage.. and voltage difference you have a IR that is actual not estimated..
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Old 07-31-2014, 06:00 PM   #25
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Only if it is an instantaneous measurement.

Measuring IR when the values in so low often in the order of 1-3 mohm accurately in real world is a non trivial exercise.
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Old 08-01-2014, 06:36 AM   #26
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Some dischargers will estimate the capacity of the battery by discharging for 60 seconds before taking an IR measurement. The first 60 seconds of discharge provides enough information for a very accurate estimation of battery capacity.
Just like the CE TurboGFX, it's the only one that measures IR on discharge and is probably the most accurate and reliable device out there.
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