Running MaxAmps batteries to under 3.xx voltage?
12-24-2007, 04:20 PM
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Running MaxAmps batteries to under 3.xx voltage?
Dear Maxamps and other MaxAmps battery users,
What voltage would you recommend running the batts to? What voltage have you actually run the batts to and what were your results?
I run all of my batteries according to a timer and have never triggered the low-voltage cut-off yet on my ESCs. When I unplug them, the voltmeter reads 3.70-3.71V and my FMA Cellpro 4S estimates this to be about 80% of capacity used. I'm very satisfied with my flight times so far. My HZ Super Cub gets 40 mins per 2100 pack, my E-flite P-47 gets 14 mins per 2100 pack, and my Twister 4S EDF Jet 800W power setup gets a comfortable 8.3 mins on 4S 4000 packs. However, I've read many other flyers running their Lipos down to 3.5V, and here on the MaxAmps website on the Lipo Care page, it says:
Use a motor speed controller which has auto-cut feature for lithium polymer. Auto-cut should be set at 3.0V per cell. A three-cell pack, therefore, should be set for 9.0V auto-cut, for example.
So is it safe to run it down to 3.0V? What are the results of running it down to 3.0V regularly, versus my 3.71V in terms of long term performance? Is the post-flight measurement inaccurate because it is not under load like it is the final minutes of flight? Everyone at the flying field doesn't believe me so they always come up to me with their voltmeters in-hand to measure my MaxAmps battery after super long flights to see if I killed it ... but they are always shocked to see such a high remaining voltage. Maybe this is just due to the flat voltage dicharge curve of these sweet batteries. I wish I had an onboard monitor to answer my own question but perhaps I could draw on the community's experience instead. : ) Thanks!
- K
What voltage would you recommend running the batts to? What voltage have you actually run the batts to and what were your results?
I run all of my batteries according to a timer and have never triggered the low-voltage cut-off yet on my ESCs. When I unplug them, the voltmeter reads 3.70-3.71V and my FMA Cellpro 4S estimates this to be about 80% of capacity used. I'm very satisfied with my flight times so far. My HZ Super Cub gets 40 mins per 2100 pack, my E-flite P-47 gets 14 mins per 2100 pack, and my Twister 4S EDF Jet 800W power setup gets a comfortable 8.3 mins on 4S 4000 packs. However, I've read many other flyers running their Lipos down to 3.5V, and here on the MaxAmps website on the Lipo Care page, it says:
Use a motor speed controller which has auto-cut feature for lithium polymer. Auto-cut should be set at 3.0V per cell. A three-cell pack, therefore, should be set for 9.0V auto-cut, for example.
So is it safe to run it down to 3.0V? What are the results of running it down to 3.0V regularly, versus my 3.71V in terms of long term performance? Is the post-flight measurement inaccurate because it is not under load like it is the final minutes of flight? Everyone at the flying field doesn't believe me so they always come up to me with their voltmeters in-hand to measure my MaxAmps battery after super long flights to see if I killed it ... but they are always shocked to see such a high remaining voltage. Maybe this is just due to the flat voltage dicharge curve of these sweet batteries. I wish I had an onboard monitor to answer my own question but perhaps I could draw on the community's experience instead. : ) Thanks!
- K
12-24-2007, 04:34 PM
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RE: Running MaxAmps batteries to under 3.xx voltage?
You are talking 2 different specs, let's seperate them into resting voltage and voltage under load (the higher the load the more spread there is between the two)
Resting voltage of 3.5 or 3.7 is considered empty and there really isn't much capacity difference.
LVC is something else and is dependant on a number of things such as current, current capability of battery, resistance and wires, ect.
It sounds like your doing just fine and there's going to be a huge difference in your 2 set-ups (40 minutes vs. 8 minutes) becuase the 8 minute set-up will spring back up a lot more in resting voltage.
does this help?
Resting voltage of 3.5 or 3.7 is considered empty and there really isn't much capacity difference.
LVC is something else and is dependant on a number of things such as current, current capability of battery, resistance and wires, ect.
It sounds like your doing just fine and there's going to be a huge difference in your 2 set-ups (40 minutes vs. 8 minutes) becuase the 8 minute set-up will spring back up a lot more in resting voltage.
does this help?
12-25-2007, 01:31 PM
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RE: Running MaxAmps batteries to under 3.xx voltage?
LVC for a single cell under load should be set at 3.0 volts per cell. I myself run 3.2 volts per cell under load. I fyou want to know what exactly is going on buy an Eagle Tree Micro Logger. I run one and it'll let you see everything your wondering about for about 70 Bucks. And never run a cell past 3.0 volts. Doing so can harm the pack.
Jason
Jason
