NIMH resistence (please read and help )  
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All Forums >> Radios, Batteries, Clubhouse and more >> Batteries & Chargers >> NIMH resistence (please read and help )
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NIMH resistence (please read and help ) - 11/23/2006 4:00:43 PM   
zephar123


 

Posts: 481
Joined: 8/7/2006
From: chowchilla, CA, USA
Status: offline 		I just put toget a battery pack for the first time. THe resistence is 18 in the battery pack. Is this decent, I heard 8 from someone, but none of my packs have a 8 resistence infact some of the premanufactured ib4200 i have have 42 RES and seem to run good. Anyhow any help and tips on this will be much appreciated. I am using the Orion gold battery bones part number 40112. If there something that I should use better please let me know. I am also use deans solder. I was wondering if I shoudl go with a solder instead that has more silver and no lead would love input on that as well. As I put out some money to get these 4200 and I want to do them right. I have enough put 3 more packs together, but am waiting on input.
       Post #: 1

RE: NIMH resistence (please read and help ) - 11/23/2006 9:38:54 PM   
Rodney



Posts: 4782
Joined: 12/8/2001
From: FL
Status: offline 		What units are you talking about Milliohms, microohoms , ohms or ????. If it is in ohms you are in deep trouble already.

(in reply to zephar123)
       Post #: 2

RE: NIMH resistence (please read and help ) - 11/24/2006 12:31:41 AM   
zephar123


 

Posts: 481
Joined: 8/7/2006
From: chowchilla, CA, USA
Status: offline 		been to long for me im not sure if its milli or micro heres the forumla please tell me. ( I should of originally put it here like this sorry 017.2m lower case m cant rember which is when I think its milliohms, but my memory bad on that.

(in reply to Rodney)
       Post #: 3

RE: NIMH resistence (please read and help ) - 11/27/2006 1:09:18 AM   
cyclops2


 

Posts: 1835
Joined: 12/23/2005
From: Frenchtown, NJ, USA
Status: offline 		Actually the internal resistance of a battery changes with the amount of charge the battery has and how large it is and the materials it is made of.
I do not know how to calculate the internal resistance.
I would not try ANY ohm meter readings.

(in reply to zephar123)
       Post #: 4

RE: NIMH resistence (please read and help ) - 11/27/2006 3:08:20 AM   
ama62206


 

Posts: 10
Joined: 4/18/2005
From: geneva, IL, USA
Status: offline 		silver is a better conductor than aluminum, copper, or gold, not to mention lead or tin. the internal resistance is something you can do nothing about, so the real question you should be asking about is external resistance ( battery interconnects, leads, connectors etc.)

(in reply to cyclops2)
       Post #: 5

RE: NIMH resistence (please read and help ) - 11/27/2006 1:36:30 PM   
richrd


 

Posts: 780
Joined: 7/18/2005
From: Waterford, PA, USA
Status: offline 		The formula for your own reference is to test at LOAD input to ESC this will verify connectors and wiring. Connect your volt meter then measure voltage at no load off.
Now go up to full load measure voltage. Rint = (No Load Volts – Full Load volts) / Amps. The amps can be measured with DMM or a watt meter. Mostly done with fully charged battery and always in milli ohms less than 10mOhms is good.
Rich

(in reply to ama62206)
       Post #: 6

RE: NIMH resistence (please read and help ) - 11/27/2006 3:30:59 PM   
Rodney



Posts: 4782
Joined: 12/8/2001
From: FL
Status: offline 		The internal resistance becomes quite important in high load (large current draw) conditions and will vary with the internal construction and materials used in manufactureing. In general, NiCad have a lower internal resistance than NiMh but the NiMh's are improving as manufacturing techniques are refined. Richrd's suggenstion will work to get a rough idea of what the internal impedance is. This will vary somewhat with the current being drawn and with temperature. The problem in getting this measurement outside a rather sophisticated laboratory as your typical home use voltmeters are not very accurate at these small (millivolt resolution) delta voltage measurements.

(in reply to richrd)
       Post #: 7

RE: NIMH resistence (please read and help ) - 11/27/2006 6:41:13 PM   
richrd


 

Posts: 780
Joined: 7/18/2005
From: Waterford, PA, USA
Status: offline 		So true Rodney. Nice to have 4 leaded meters with 5 digits oh well but for home referance and wiring connections it's suprising how good a referance these these tests can do, even with harbor fright meters. What else can you do when it's raining.
Rich

(in reply to Rodney)
       Post #: 8

RE: NIMH resistence (please read and help ) - 11/28/2006 3:23:40 PM   
rmw00



Posts: 116
Joined: 3/12/2002
From: Indianapolis, IN, USA
Status: offline 		The latest SubC sized NiMH's have lower resistance than NiCd cells. They are commonly used at over 200A for FAI competitions.


_____________________________

Ralph Weaver
Indianapolis, IN USA

(in reply to richrd)
       Post #: 9

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