EMRFD Message Archive 12948

Message Date From Subject
12948 2016-06-10 08:51:09 ka3j12 9V Li-ion Battery Capactiy

Does anyone have experience using one of these batteries or knows whether or how much the rated capacity degrades under a heavy load?  I was hoping to use one rated at 600 mAh in a rig that draws 200 - 300 mA, on transmit and a bit under 100 mA on receive.   Will the heavy draw, especially on trasmit effectively reduce the mAh rating and if so what might it be assuming 50% transmit time?  I was hoping to get 1-2 hours of operating time from it.  Is this feasible?  Thanks


Ron (KA3J)


12949 2016-06-10 09:13:30 Dave Miller Re: 9V Li-ion Battery Capactiy
Without testing you won't know for sure.  
But generally Li-ion secondary batteries do not have the load related electro-chemical affect of let's say Lead based batteries.  
From what you say your peak draw is .5C. In other words you should get 2 hours of discharge at your rated discharge.   If your internal resistance of the pack is reasonable you should get the results you want.  
The nice thing about Li-ion is the rated Mah is real and tested at a useful discharge of .5 to 1C.  Not like other types of batteries that the rated  capacity is at a 1/20C. Discharge. 

You do need to consult the data sheet on a battery.  

9V is a strange Li-ion pack voltage.  Is this a primary or secondary cell ?

Also in any Li-ion system you for safety must monitor and prevent battery abuse.  ( over discharge , overcharge etc)

Please provide a link to the battery in question if you want any more information.  

Dave
VE7HR/VE7PKE



Sent from my iPhone

12950 2016-06-10 09:22:38 ka3j12 Re: 9V Li-ion Battery Capactiy
Dave,

Thanks for your response.  The battery in question is the EBL 6F22 shown here (actually 8.4V):

Reviews seem generally decent but I couldn't find any explicit test results in the comments or elsewhere on the internet.  Thanks.

Ron

12951 2016-06-10 09:50:37 Dave Miller Re: 9V Li-ion Battery Capactiy
Ron,

Thanks for the link.  Until proven otherwise in actual test I would say those are not the battery for your application.  Those are designed for very low rate discharge and probably would not even work for a short period of time.  

Find yourself some model car or airplane packs.   Cheaper and better suited to application.  

Dave
VE7HR


Sent from my iPhone

12952 2016-06-10 10:02:22 Dennis Czelusniak Re: 9V Li-ion Battery Capactiy
Below quoted from cell mfg. website.
"You can approximate how long a battery will last by dividing its total charge (in mAh) by your nominal load current (in mA). Say you have a 1800 mAh battery, and you connect it to a 20 mA load:

1800 mA⋅h20 mA=1800mA⋅h20mA=90 h"

It is best to refer to cell mfg. data sheet which will show you capacities at various loads.



--------------------------------------------
12953 2016-06-10 10:20:26 Dana Myers Re: 9V Li-ion Battery Capactiy
12956 2016-06-10 12:03:36 dpflugrath@juno.c... Re: 9V Li-ion Battery Capactiy
Check out spiderbeam. They also sell individual segments
Dan KA7GPP

Please note: message attached