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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Dennis Adamisin on August 14, 2017, 07:15:56 AM
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According to the Battery University, charging to 4.1V/cell instead of 4.2V/cell will double the cycle life of Lipo's as quoted from here:
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
"Most Li-ions charge to 4.20V/cell, and every reduction in peak charge voltage of 0.10V/cell is said to double the cycle life. For example, a lithium-ion cell charged to 4.20V/cell typically delivers 300–500 cycles. If charged to only 4.10V/cell, the life can be prolonged to 600–1,000 cycles; 4.0V/cell should deliver 1,200–2,000 and 3.90V/cell should provide 2,400–4,000 cycles."
I think most chargers can be programmed to charge to a lower peak. Of course if you start at a lower voltage you discharge deeper too - so it probably cannot be done if you are using more than 65%-70% of capacity. However I am I am currently flying a couple airplanes for which that is not a problem.
Just curious if anyone is actually using a 4.1V charge and what your experience is?
...and THANKS in advance for sharing your experience.
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No direct experience, but that matches what I was told by a Tenergy applications engineer on a work project where we were designing their batteries into a product.
It'd be good to know just how much capacity you leave on the table, and what the best tradeoff is between stuffing the last electron in on charge vs. sucking the last one out on discharge.
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Lost capacity should be easy to test: charge to 4.1 and then charge ( but don't balance) to 4.2.
The extra amount put in is what you are giving up.
But you will draw the battery a bit lower in discharge, both because you are starting off less than fully charged and because the average voltage is lower.
Energy(W-hours) flies the model through the pattern, not capacity.
How this all comes out in battery life would be interesting to know.
Best way to test this would be a single user to have two sets of batteries and run them each way for a while (a season perhaps) and compare them.
Pat MacKenzie
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Hi Dennis,
Igor has been doing this for years. That's how he gets plus 200 flights out his battery packs. Sure.....you do need a bigger pack than usual, but in his case with a 6 cell pack in his Max Bee, the battery is cruising and not stressed. The battery university site is an excellent source of info on all types of batteries. One of the other killers of lipo's is to keep it fully charged, even like the night before flying. I found that charging to 80% the night before works fine and then I top them up before I start flying. Maybe Igor will add something here. He uses one battery pack in his plane as well and fast charges them.........carefully before each flight using a very good charger. I seem to remember it is an older FMA charger.
If you're in the lucky position of having some models that use only 60% of a charge then it will be easy for you to test that, so please keep us posted. Thanks.
Keith R
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Yes, I charge battery just before flying, so it does not stay charged too long. and I store them discharged after flight. I cut charging at 2A so it is not fully charged anyway. I also do not balance them at every charge, I do it after aproximately 10 flights. If I see tendecy to disbalance, means battery is already bad so I simply replace. They do usually 200 to 400 flights.
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THANKS for info.
The Battery University info sounds pretty compelling and within the rest of the article it makes it sound like under-peak charging is being done routinely with consumer devices & electric cars to extend battery life. My batteries are already well seasoned but I figure on trying this out before I break in their replacements.
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After flying for a couple years with full charge batteries 4.20 charge and experiencing lots of short life and extremely unbalanced cells batteries, Less than 50 charges On Hobby King cheap batteries .
I have cut down the max charge to 4.14 volts and went to a over capacity battery . With changing to a thunder-power battery , the battery voltage is 3.8 after flight , right at storage charge.
The model needed the nose weight , so extra battery capacity and lower voltage full charge was not a issue .
No battery failures with over 100 cycles on battery 1
Might be something to not charging to 100 % and not discharging too deep.
Lesson learned , do not buy chaap batteries, they are not really cheaper and follow Igor's advice