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? ThanksRon (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.DaveVE7HR/VE7PKE
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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):https://www.amazon.com/EBL-Self-Discharge-Lithium-ion-Rechargeable-Batteries/dp/B00EQ3U2AA/ref=sr_1_1?ie=UTF8&qid=1465575558&sr=8-1-spons&keywords=ebl+9v+li-ion+battery&psc=1Reviews 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.DaveVE7HR
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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 email@example.com... Re: 9V Li-ion Battery Capactiy Check out spiderbeam. They also sell individual segments
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