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Aug 17, 2019, 08:05 AM
Registered User
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Odd Problem


Hi Ya'all

I'm running a 450 quad with a 4s system and have suddenly developed a voltage drain. Not a current drain, a voltage drain. I'm using 10,000mah batteries, one new, that start out at 16.8 volts and 10,000mah. By the time the battery is half used, (5,000mah), the voltage has dropped to 14.5 and if I let it go the full 10,000, it drops below 14v. This is new and normally the battery is at 14.7 @10,000mah. Any Ideas?
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Aug 17, 2019, 08:47 AM
Registered User

Voltage reductions are only from


Current flowing out of the battery & being used up in some way. No exceptions to that rule of voltage and current.
Something is pulling out current...…………. It can even be a current drain in the battery itself. Recharge itlet it rest over night read voltage next day read voltage each day for 3 day. drops ? bad but maybe a usefull battery...……….. But be aware . The battery could go to a short & flame up. That does happen keep that big thing AWAY from anything that can burn. !0 to 20 feet minimum WITH A METAL garbage can cover over it as a flame & spar spreading guard. That LIPO is a powerfull danger.

You are in the LIPO fires are real class & losing the building it is in.
Aug 17, 2019, 10:54 AM
Registered User
Voltage can only drop, it is not something that drains.

You are describing a completely normal voltage curve as SoC drops in use.

For longevity, stop discharging so that after an isolated rest period, voltage bounces back up to 3.7Vpc

Going below 3.2-3Vpc regularly will drastically shorten lifespan.

When the voltage drops much faster / earlier, that shows a battery that is wearing out, may have reached EoL.

A CC load capacity test will confirm their SoH state of health as a % of the original when new. EoL is usually at 70-75%.

Be very careful LiPo get very risky in that state, follow safety protocols in disposal.
Aug 17, 2019, 11:10 AM
Space Coast USA
hoppy's Avatar
Quote:
Originally Posted by rjriggins11
Hi Ya'all

I'm running a 450 quad with a 4s system and have suddenly developed a voltage drain. Not a current drain, a voltage drain. I'm using 10,000mah batteries, one new, that start out at 16.8 volts and 10,000mah. By the time the battery is half used, (5,000mah), the voltage has dropped to 14.5 and if I let it go the full 10,000, it drops below 14v. This is new and normally the battery is at 14.7 @10,000mah. Any Ideas?
Never let a lipo pack go to full discharge, in this case 10,000mah. You should stop flying with 20% of the batteries capacity left. That would be 3.7V/cell after disconnecting the battery after a flight. Looks like you just flew it too long. The 3.7V/cell after landing is the number you should be concerned with.
Aug 17, 2019, 11:32 AM
I'd rather be Flying
davecee's Avatar
Quote:
Originally Posted by rjriggins11
Hi Ya'all

I'm running a 450 quad with a 4s system and have suddenly developed a voltage drain. Not a current drain, a voltage drain. I'm using 10,000mah batteries, one new, that start out at 16.8 volts and 10,000mah. By the time the battery is half used, (5,000mah), the voltage has dropped to 14.5
Quote:
Is this under load or at rest after a short recovery time?
and if I let it go the full 10,000, it drops below 14v.
Quote:
same question
This is new and normally the battery is at 14.7 @10,000mah.
Quote:
same question
Any Ideas?
If under load, have you made any changes that would have increased the load? New props? Heavier weight? Also, IR will generally increase with use, especially if the batteries are run to a high temperature and also if run consistently to empty. This can show as lower voltage under load.
If at rest, the older battery (batteries) may just be losing capacity, which is also normal. Is the new battery a different brand, c rating, or the same but bought at a different time (different production lot)? In any of these cases you cannot expect exactly the same performance as other batteries. These are hobby quality products. You cannot expect all batteries that are rated the same to perform exactly the same. 10,000 mah capacity is just an approximation. Hopefully it's close to reality, but it's not always so.
Aug 17, 2019, 03:11 PM
Bombs away! Err...landing
Ira NZ's Avatar
Quote:
Originally Posted by rjriggins11
Hi Ya'all

I'm running a 450 quad with a 4s system and have suddenly developed a voltage drain. Not a current drain, a voltage drain. I'm using 10,000mah batteries, one new, that start out at 16.8 volts and 10,000mah. By the time the battery is half used, (5,000mah), the voltage has dropped to 14.5 and if I let it go the full 10,000, it drops below 14v. This is new and normally the battery is at 14.7 @10,000mah. Any Ideas?
Are you regularly overdischarging it like that? It sounds like what you're seeing is what you'd expect, damage and loss of capacity due to overdischarging.
Aug 17, 2019, 03:55 PM
Registered User
A LVC of 3.5Vpc is 14V

At very high discharge C-rate, that will likely bounce back to 3.7V resting.

Which of course is more stressful than a shallower DoD cycling pattern,

but seems to me many many users regularly do go lower than that, and just buy replacement packs more frequently.

Which of course is fine, once they're not doing so just out of ignorance.
Aug 17, 2019, 05:02 PM
Frankenstein recycled packs
rampman's Avatar
rjriggins11, nothing like destroying a battery.

Rick
Aug 17, 2019, 07:54 PM
Registered User

I remember seeing ESC with 3.5 v cutoffs. NO changing it.


Oh well. They are business people making money by letting the plane fly longer. Nice caring people.
Aug 17, 2019, 11:24 PM
Registered User
Thread OP
The good news is, I didn't damage the battery that I can tell. I'll run it thru a few more cycles just to be sure. I'm going to try lightening the load and see if that makes a difference.
Aug 17, 2019, 11:29 PM
Registered User
Thread OP
Quote:
Originally Posted by cyclops2
Oh well. They are business people making money by letting the plane fly longer. Nice caring people.
Yeah. And their accurate too. I was doing a hover test and it landed nicely at 10,008mah on the screen. I'm using a Vector system and it seems to do nicely for a Quadcopter.


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