LiPo Cell Inflation

[49er]

I've been having some real problems with Thunder Power LiPo cells "inflating" after a dozen recharge cycles. I'm using a "smart" charger and the batteries are never deeply discharged or stressed anywhere near their rated amperage. What can be the cause for this?06 - LiPo After 6 Minutes.JPG

[egneg]

What exactly is a "smart" charger? What amp rating are they being charged at?

[49er]

The recharger is a Thunder Power 610C with auto balancing set for 4 amps max current.

The "infltion occurs during usage, or discharge, usually about halfway through the normal run time.

[JimClark]

what is your setup, prop, boat motor ecs ect and how long are you running it for? How much is left int he battery after a run?

[49er]

The boat is a 27 inch wooden deep vee (a Dumas DV-20 "expansion" photos in the folder that I posted today under the name "Infinity and Beyond). The motor is a Leopard 3674 2200Kv with a hobby Wing Sea King 60 esc turning an Octura X637 prop. The measured max amps on the pond are 45 to 48 (whether running either a LiPo or NiMH battery. I usually run about 8 minutes from a 5000 mAH battery regardless of battery type, but the photo "inflation happened in less than 6 minutes. When recharging after an 8 minute run, either type of battery rarely takes more than a 3000 mAH recharge.

[Fluid]

Something is really wrong here. Your run time and capacity used means you are averaging just 22 amps - that must be one slow boat! With that prop you should be drawing much more than that. And the packs should not be puffing that badly with ~50% still left. Perhaps your charger is not charging them fully so you are actually drawing them down a lot more than you think. What is the pack voltage after a charge? What is the temperature of the pack when you get back to the beach? What is the resting voltage back on shore?


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[49er]

Indeed, I probably only average 20 to 25 amps during a "normal" run. I'm a sport boater, not a racer, and I spend a lot of time running at less than full throttle chasing a couple of slower boats that my buddy runs. Check the last picture in the album "infinity and Beyond" that I posted yesterday. The photo shows the boat on an early run last summer moving at a speed that I later measured at an even 40 MPH with a Bushnell sports radar. As I noted earlier, the max amps drawn by this setup usually range between 45 and 48 depending on wave conditions. I've measured current draw and operating RPM of all my boats over the past 5 or 6 years with a "Medusa Research" data logger. Though I don't measure the running temps of the battery packs regularly, after a "normal" run, the LiPo pack was never more than 10 or 20 degrees warmer than air temp and the NiMH pack was only slightly warmer. The voltage of either type of battery pack after each run is usually within a few tenths of the rated voltage.

[lenny]

Where are the pictures at, Do you have a link ?

[Fluid]

The voltage of either type of battery pack after each run is usually within a few tenths of the rated voltage...

It is difficult to help when the OP fails to answer several important questions. What is the fully-charged voltage of your pack? What is this "rated voltage" you refer to? What does "within a few tenths" mean - is it above or below the "rated voltage"? If you consider the LiPo 'rated voltage' to be 3.7 volts per cell, then if the pack reads 3.6 volts per cell after a run it is clearly well past 75% discharged and pretty dead. Running LiPos down to low voltage - even slowly - can damage them permanently. The puffing you see may be a result of past abuse.

Too, if the boat is actually running 40 mph it is clearly drawing more than 45 peak amps. This all could be due to a bad pack, but there is just too much here which makes little sense.



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[iridebikes247]

This is weird. Cheap packs swell quickly if the voltage goes too low, this isn't a cheap pack....That thing did a great job of blowing out the plastic casing. It has to be going too low. Anything below 3.7 volts means its dead but was way lower than that under load in the boat.

[785boats]

There's been trouble with the newer TP packs at our club too. For no apparent reason a cell puffs or suddenly has high IR after a run or is at a much lower voltage than the other cells in the pack. Even though it was perfectly charged & balanced prior to the run.
Here's one that failed only two laps into a race on a moderately loaded setup. As you can see the other cells are perfectly square & hard. I converted it into a 2s pack for him & it is still going strong. Ive repaired a few over the last year.
Sometimes, you just DON'T get what you pay for.

[oscarel]

There's been trouble with the newer TP packs at our club too. For no apparent reason a cell puffs or suddenly has high IR after a run or is at a much lower voltage than the other cells in the pack. Even though it was perfectly charged & balanced prior to the run.
Here's one that failed only two laps into a race on a moderately loaded setup. As you can see the other cells are perfectly square & hard. I converted it into a 2s pack for him & it is still going strong. Ive repaired a few over the last year.
Sometimes, you just DON'T get what you pay for.

Did you contact TP for warranty? They do have a 2 year replacement on them.

[785boats]

No, it wasn't my battery.
He just asked me to make a 2s out of it. I don't think he wanted any more TP packs after a few had given up cell to the Lipo gods.

[Make-a-Wake]

I don't see anywere the mah or "C" rating of the packs....................or even the cell count, hard to determine the problem without that info.

I think your boat is "plowing" if the cells are high quality.