Weird lipo question
11-23-2010, 04:07 PM
#1
Weird lipo question
I own a bunch of venom lipos so far so good. i just picked up another one with 50c and got home and noticed a difference. the new 50c one is 2s2p while my other 40c's are 2s1p. what is the diff here? obvious the 2p has more packs inside of it. but is this a pro or a con?
thanks for any and all info!
thanks for any and all info!
11-23-2010, 04:38 PM
#4
Its this one: http://www3.towerhobbies.com/cgi-bin...?&I=LXZDW3&P=7
Its actually smaller(shorter) than my 40c's because for some odd reason the 40c's have bumps on bottom of case and this new one is flat.
Its actually smaller(shorter) than my 40c's because for some odd reason the 40c's have bumps on bottom of case and this new one is flat.
11-23-2010, 06:47 PM
#5
Didn't see that one. I wonder if those are saddle paks stuffed into a hard case? That could explain why the 2P...anyway, at least its not any bigger.
There's been a lot of grousing about those bumps on hard cases. Apparently there are more RCs with flat trays than with batt cell cutouts.....
There's been a lot of grousing about those bumps on hard cases. Apparently there are more RCs with flat trays than with batt cell cutouts.....
11-25-2010, 03:08 PM
#7
Tech Apprentice
How to check remaining capacity(mAh) in lipo
When i balance charge my new Turnigy 2s 5800mAh using Thunder AC6 at 5.0A, i understand that it will charge the lipo cell from whatever remaining voltage per cell to 4.2v per cell.
For example if the 2s are at 3.85v and 3.89v, it will balance charge to 4.20v and 4.20v.
I understand that my Thunder AC6 lipo charger is limited to 50Watts and 5.0A charge rate.
To charge my new Turnigy 2s 5800mAh, it should take around 8.4v x 5.8A = 48.72Watts in 60mins.
But again with my charger limited to 5.0A, it only charges at 8.4v x 5.0A = 42Watts which means it takes around 70mins+ to reach full capacity.
My questions are:
1. If i overcharge (without balance charge) my new 2s lipo above 8.4v, let's say 8.6v, how do i bring down the voltage?
2. When i charge my other new lipo in balance mode, it perfectly balanced to 8.4v but the charged capacity reading was at 2989mAh. Does this mean the charger top up the capacity or only charged at 2989mAh?
3. Is there any device to monitor lipo capacity?
For example if the 2s are at 3.85v and 3.89v, it will balance charge to 4.20v and 4.20v.
I understand that my Thunder AC6 lipo charger is limited to 50Watts and 5.0A charge rate.
To charge my new Turnigy 2s 5800mAh, it should take around 8.4v x 5.8A = 48.72Watts in 60mins.
But again with my charger limited to 5.0A, it only charges at 8.4v x 5.0A = 42Watts which means it takes around 70mins+ to reach full capacity.
My questions are:
1. If i overcharge (without balance charge) my new 2s lipo above 8.4v, let's say 8.6v, how do i bring down the voltage?
2. When i charge my other new lipo in balance mode, it perfectly balanced to 8.4v but the charged capacity reading was at 2989mAh. Does this mean the charger top up the capacity or only charged at 2989mAh?
3. Is there any device to monitor lipo capacity?
11-25-2010, 04:05 PM
#8
A charger by design is able to deliver a certain output power and a certain maximum charge rate. These are fixed by the rating of the internal components (big player in the charger's cost). Charge time is a function of charging rate not capacity, any discharged lipo of whatever capacity should take about an hour to charge at a 1C charge rate. If lipo is not completely discharged, it will be require less timt to recharge.
Lipo charge protocol is CC/CV (constant current/constant voltage) and even without the balancer attached, charger should not allow lipo to overcharge above 8.4v (2S). If it does, charger is potentially dangerous to use. I'm not referring small calibration probs, but usually these chargers are set up so if there is an error in calibration it is on the low side, ie if charger indicates 8.40v, its actually 8.38v or something like that. You can use the discharge mode to bleed some voltage off, but it shouldn't be happening in the 1st place. 8.6v would be a serious overcharge.
Lipos are delivered partially charged, so that was all it took to top off your new lipo. If these were 5800mah as well, that's a little over 50% and that's about where they should be when new. The most accurate device to monitor mah is a wattmeter like the plane guys use. CellPro, Powerlog, Wattmeter etc, the device goes by several names and has to be wired in line with the battery so it can measure amps directly.
Lipo charge protocol is CC/CV (constant current/constant voltage) and even without the balancer attached, charger should not allow lipo to overcharge above 8.4v (2S). If it does, charger is potentially dangerous to use. I'm not referring small calibration probs, but usually these chargers are set up so if there is an error in calibration it is on the low side, ie if charger indicates 8.40v, its actually 8.38v or something like that. You can use the discharge mode to bleed some voltage off, but it shouldn't be happening in the 1st place. 8.6v would be a serious overcharge.
Lipos are delivered partially charged, so that was all it took to top off your new lipo. If these were 5800mah as well, that's a little over 50% and that's about where they should be when new. The most accurate device to monitor mah is a wattmeter like the plane guys use. CellPro, Powerlog, Wattmeter etc, the device goes by several names and has to be wired in line with the battery so it can measure amps directly.
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