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Murphy's Law

Anything to do with gliders & gliding.
IanT-White
Posts: 36
Joined: 31 Jan 2020, 16:17
Location: East Yorkshire

Re: Murphy's Law

Post by IanT-White »

Re the remaining capacity of a LiFe battery , I like to add up how long I have used /flown a model during a long session on freshly charged batteries and
when back home recharge them on a charger that shows how much current has gone into the battery to fully recharge it.
For example say you have flown for 90 minutes and you needed about 900 milliamps to fully charge your batteries , then you consume about 100 milliamps say for a 10 minute flight or 600 milliamps for 60 minutes flying or 900 milliamps for 90 minutes
If you apply a safe discharge of two thirds of the batteries capacity , say 2700 milliamp capacity battery reduced to 1800 milliamp which would give you about 180 minutes /2 hours flying . The timer on your transmitter can give you info on how long its been on/model flying.
Sorry its not super scientific but the above does seem to work and avoids running out of power .
I use a small note book for my models and note the info for each model including discharge rate .
Most models require lead ballast and I am a big fan of using a larger battery needing less lead , sound investment !
As others have said , with a flat discharge rate that drops off rapidly when nearly discharged , its more difficult to monitor your batteries based on voltage . Whatever , may your batteries support your model .
Ian Turney-White
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Peter Balcombe
Posts: 1399
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Murphy's Law

Post by Peter Balcombe »

Good idea to use recharge capacity to check what has been taken out of the battery 👍
Also probably an idea to also periodically check the overall capacity to make sure you have an indication of what is being left in the pack (as pack capacity drops over time) before recharge.
Peter
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mjcp
Posts: 183
Joined: 29 Jul 2015, 08:14
Location: A wind swept hill with no wind, in driving distance of Windsor, UK
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Re: Murphy's Law

Post by mjcp »

Guru of all things OpenTx and its use in gliding, Mike Shellim, has a blog post on timing / LiFe battery use via the Tx:

http://rc-soar.blogspot.com/2016/09/usi ... fe_94.html
m̶j̶c̶p̶ Marc

Hanger -
Some (now) pristine models that are un-flown for a year.
Chris Veitch
Posts: 47
Joined: 21 Mar 2015, 07:57
Location: Northallerton, North Yorkshire

Re: Murphy's Law

Post by Chris Veitch »

Roger

Sorry to hear of your incident, we have all had challenges of our own making one time or other. I remember once forgetting to connect an elevator ........

On the subject of batteries. I have never been persuaded by the LiFe approach, as it needs a lot of care, or programming to be safe. My approach to anything that is special / expensive, where it will fit, is now 2 packs of 2s li-on with an electronic switch, normally Emcotec, low cost v the £s flying with simple charging and monitoring v voltage in the pack which just leaves the dummy onethe sticks to worry about!

Regards
Chris
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