See the video for an example. When I hit the throttle the car stutters before it takes off. Doesn't happen all the time and seems to happen more as the batteries get low. It's a Losi DB XL that was converted to lipo, I have a Mamba 2 speed controller, a leopard 4 pole motor and running 2 4s packs.
Why does my lipo car "stutter"?
- Thread starter polishdon
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atom3624
Well-Known Member
The vehicle is quite heavy, and will have quite a high requirement of power - this is provided by the batteries to the ESC, to the motor.
Let's say the motor at FULL POWER can pull up to 200A, but the ESC can only provide 180A - you have a 'weak link' in the ESC and will probably damage it.
Let's continue - motor pulls 200A, ESC can provide 250A - then there's no problem there.
If you have a 6Ah battery - doesn't matter in this example if it's 4S, 5S, 8S .. we're looking at power demand.
If the battery is rated at 20C continuous, this means it can supply 20 x 6A = 120A.
This is MUCH LESS than the 200A the motor can require on occasion - normally at start up and at maximum speed - most power demand. LiPo battery will start swelling up - common in under-performing LiPo batteries.
If you have a 6Ah (6000 mAh) battery rated at 50C continuous = 6 x 50 = 300A - then the battery covers, the ESC, which covers the motor - sorted.
You should also install (or set if its part of the ESC) the LOW VOLTAGE CUT-OFF.
Normally this is 3.3 V, but most set it at 3.7 V to allow for droop, or power surge when in use.
IF ALL OF THE ABOVE IS CORRECT, next look at the gearing.
It might simply be over-geared for the power of the battery / ESC / motor combo and they're trying too hard - this is now called COGGING - very common by people trying to get too much speed.
A certain sign of over-gearing is the motor / ESC and sometimes the battery will get warm - motor and ESC VERY HOT - not good.
Hope this helps.
Al.
Let's say the motor at FULL POWER can pull up to 200A, but the ESC can only provide 180A - you have a 'weak link' in the ESC and will probably damage it.
Let's continue - motor pulls 200A, ESC can provide 250A - then there's no problem there.
If you have a 6Ah battery - doesn't matter in this example if it's 4S, 5S, 8S .. we're looking at power demand.
If the battery is rated at 20C continuous, this means it can supply 20 x 6A = 120A.
This is MUCH LESS than the 200A the motor can require on occasion - normally at start up and at maximum speed - most power demand. LiPo battery will start swelling up - common in under-performing LiPo batteries.
If you have a 6Ah (6000 mAh) battery rated at 50C continuous = 6 x 50 = 300A - then the battery covers, the ESC, which covers the motor - sorted.
You should also install (or set if its part of the ESC) the LOW VOLTAGE CUT-OFF.
Normally this is 3.3 V, but most set it at 3.7 V to allow for droop, or power surge when in use.
IF ALL OF THE ABOVE IS CORRECT, next look at the gearing.
It might simply be over-geared for the power of the battery / ESC / motor combo and they're trying too hard - this is now called COGGING - very common by people trying to get too much speed.
A certain sign of over-gearing is the motor / ESC and sometimes the battery will get warm - motor and ESC VERY HOT - not good.
Hope this helps.
Al.
- Thread starter
- #3
Thanks Al. I am using one Glacier 5000mah rated at 55C and one Turnigy 5000mah rated at 20-30C.
When I plug in the ESC I get the 8 beeps, which according to the manual is telling me the low voltage cut off is set. My question is, what happens when it hits that cut off point, does the ESC give you some kind of signal? I've been very careful about not running down the batteries too far, but was wondering if this stuttering was a sign that the batteries were low as it's more frequent the longer I use it.
When I plug in the ESC I get the 8 beeps, which according to the manual is telling me the low voltage cut off is set. My question is, what happens when it hits that cut off point, does the ESC give you some kind of signal? I've been very careful about not running down the batteries too far, but was wondering if this stuttering was a sign that the batteries were low as it's more frequent the longer I use it.
atom3624
Well-Known Member
Varies with the ESC's.
Some may give reduced power, make a noise, to give a very limited 'limp home' ability; others just beep, then stop - both meant to ensure you don't damage your LiPo (difficult to recharge once below a certain voltage and CAN cause fires).
Al.
Some may give reduced power, make a noise, to give a very limited 'limp home' ability; others just beep, then stop - both meant to ensure you don't damage your LiPo (difficult to recharge once below a certain voltage and CAN cause fires).
Al.
Joseph Martinez
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How can I recharge a Lipo battery that was drain real low
Thank you
Thank you
atom3624
Well-Known Member
You have to be really careful and set a low charge current using a NiMH setting until the voltage reaches above 3.3V / cell.
THEN, try charging using the correct settings.
CAUTION - THIS CAN BE DANGEROUS so be prepared for the possibility of a faulty / overheating cell - look for swelling during charging and particularly any big temperature changes.
To give an idea, check out LiPo fires on YT!
Al.
THEN, try charging using the correct settings.
CAUTION - THIS CAN BE DANGEROUS so be prepared for the possibility of a faulty / overheating cell - look for swelling during charging and particularly any big temperature changes.
To give an idea, check out LiPo fires on YT!
Al.