I have ran 2 different Checkpoint 5400s and both have swelled after or durning racing. I have used 2 different ESCs, one LRP Comp and one Speedpassion. The only thing in comon is the motor, Novak 4.5. The car is not over geared, and motor does not get hot. What could be the the issue? This last time I tried to charge one, the battery lost al volts. It will not even take a charge now.

How long do you go before charging them?

Is your lipo cut-off on:rolleyes:

traxxas trucks
+1

Overdischarging a lipo will create swelling. If your ESCs don't have cutoffs, you can buy one that you solder into the ESC and then your safe.

They usually set a week, till the next race.
I have no troubles during the race and yes, lipo cut off is turned on. I have never hit that point of cut-off with a 5400 in a 5 minute race.

The 5400 is not a high C rate battery. It is only rated at 16C. You would think that should be enough, being as that comes out to 86 amps, but the 1/8th electric guys have found out that motors that pull a lot of amps can overtax a LiPo and cause swelling even though the ratings imply there should be no problems. (I said "imply" deliberately.)

So the conclusion I would draw is that your 4.5 is just too much for the 16C 5400s. The 1/8th electric guys have also found that you can make a marginal pack last longer by not drawing it down all the way. By running to the cutoff, you may be drawing lots of current when the pack doesn't have the ability to supply it. The voltage could drop so fast, the cutoff can't kick in fast enough. If you had an adjustable cutoff, setting it to a higher value (like 3.4 or 3.5V per cell) would probably give you better life and eliminate swelling.

Or just get some higher C rated packs.

I think I agree, the packs may not quite be up to the task (I would not have guessed they weren't) How much capacity are you using in the 5 minute time period?

Many batteries can't deliver half of thier rating.

=1 to ta man.

I would ask if you balance the battery everytime you use it? When you have the situation ta_man indicated, what happens is the battery can't handle the amp draw and it goes out of balance more easily than in normal conditions. Once out of balance one cell is geting over dischaged and the other is getting over charged...then it swells. This was a problem with all of the lower C rated batteries in high amp draw conditions...

Bottom line...If you can hook up a 4.5, it's probably too much for the Checkpoint.

Ta Man is right on trarget with his answers. Sounds like he may have nailed it.

I was told it was probably the amp draw. I have it in a sprint and its hooked a lot of the times. It usually only uses about 1/2 the pack compacity. We only run 4 minutes sorry. I balance it once a week. I have a higher C rated lipo on the way. Hope this doesnt keep happening.

Thanks for the info guys.

Dont know what you are getting but id suggest a SMC C-max 40c think 5200 battery..... that should be awsome:thumbsup:

I didn't really see enough info listed here to address the question asked.

what causes lipo swelling

The way the question is asked, there are still too many variables, and other questions.

1) When DID the LIPO Swell? (during a race, during charging, while just sitting in the car between race days, other?)

2) How is the battery Charged? (What type of charger, what settings, ie: LIPO/NiMh/NiCad, what Amp setting (1c, 2c, 3c?)

3) How much is being used/put back INTO the pack on recharge?

It's mentioned that it's a Checkpoint 5200 pack and being used in a sprint car with a 4.5 motor, and race times are 4 minutes.

Is this an OLD 4.5 motor (Non-Sintered Rotor) or a SINTERED Rotor motor?

The basics that will cause Swelling -

OVER DISCHARGE, especially FAST Over Discharge, but a car left PLUGGED IN or with the battery connected between race days can cause a TOTAL discharge, and swell or ruin a LIPO)
OVER CHARGE, Charging to a voltage higher than reccomendations by the factory can cause swelling. (A lot of times this is done on accident with incorrect Charger Settings)

EXCESSIVE HEAT, Heating a lipo beyond it's suggested heat range can cause swelling. If the car pulls excessive amp load, it can drop the voltage too far, and/or cause the battery to get too warm. (You mentioned it wasn't hot...so it's doubtful (A) that the battery is TOO low "C" rating, and (B) it doubtful you are pulling enough AMPS to KILL IT...but without more info - NOBODY can know - only speculate.

one ls tthing not mentioned. If you're not balancing your lipo. And the cells become unblanced. Even if you charge to 8.4 or have a cut off. WIth one cell really off. Even by a volt. For example 3.2 and 5.2 cell volatages willg et you your 8.4 except you just blew a cell. Or same for discahrnging. you can be set at 6.8 with one cell at 4.2 and another at 2.6. You just over discharged that cell. Things to keep in mind. And running a battery like that with amottor like tht will only makes matters worse if you arent balancing.

I didn't really see enough info listed here to address the question asked.

what causes lipo swelling

The way the question is asked, there are still too many variables, and other questions.

1) When DID the LIPO Swell? (during a race, during charging, while just sitting in the car between race days, other?)

2) How is the battery Charged? (What type of charger, what settings, ie: LIPO/NiMh/NiCad, what Amp setting (1c, 2c, 3c?)

3) How much is being used/put back INTO the pack on recharge?

It's mentioned that it's a Checkpoint 5200 pack and being used in a sprint car with a 4.5 motor, and race times are 4 minutes.

Is this an OLD 4.5 motor (Non-Sintered Rotor) or a SINTERED Rotor motor?

The basics that will cause Swelling -

OVER DISCHARGE, especially FAST Over Discharge, but a car left PLUGGED IN or with the battery connected between race days can cause a TOTAL discharge, and swell or ruin a LIPO)
OVER CHARGE, Charging to a voltage higher than reccomendations by the factory can cause swelling. (A lot of times this is done on accident with incorrect Charger Settings)

EXCESSIVE HEAT, Heating a lipo beyond it's suggested heat range can cause swelling. If the car pulls excessive amp load, it can drop the voltage too far, and/or cause the battery to get too warm. (You mentioned it wasn't hot...so it's doubtful (A) that the battery is TOO low "C" rating, and (B) it doubtful you are pulling enough AMPS to KILL IT...but without more info - NOBODY can know - only speculate.

1. One swelled during a race the other over the week or after racing
2. CE t35 GFX, Lipo, 2c 5400 - Balanced every week before the first heat.
3. About 1/2 compacity was being drained
4. Motor is a 4.5 with a sintered rotor. Motor and battery never got hot.

I didnt know about not leaving a lipo plugged in. I cant remember if I did or not. I'll make sure not to do that now. Thanks

where did you store the battery?

garage
house

Always in the house.

Are you charge balancing or dis-charge balancing ????? What balancer are you using ??????
You should be balancing well you are charging.

Are you charge balancing or dis-charge balancing ????? What balancer are you using ??????
You should be balancing well you are charging.

charge balancing with a Checkpoint balancer.

The 5400 is not a high C rate battery. It is only rated at 16C. You would think that should be enough, being as that comes out to 86 amps, but the 1/8th electric guys have found out that motors that pull a lot of amps can overtax a LiPo and cause swelling even though the ratings imply there should be no problems. (I said "imply" deliberately.)

So the conclusion I would draw is that your 4.5 is just too much for the 16C 5400s. The 1/8th electric guys have also found that you can make a marginal pack last longer by not drawing it down all the way. By running to the cutoff, you may be drawing lots of current when the pack doesn't have the ability to supply it. The voltage could drop so fast, the cutoff can't kick in fast enough. If you had an adjustable cutoff, setting it to a higher value (like 3.4 or 3.5V per cell) would probably give you better life and eliminate swelling.

Or just get some higher C rated packs.

+ 1
In addition to what ta_man said ...........Some of the LRP speedo's from what I've read and seen myself with some of my friends LRP's is that the cut-off is very bad on them.
Any Lipo should not be charged when they are cold, below 60*
There is no reason not to use a balancer every time you charge. It takes no longer if they are in balance, It will prevent over charging one cell.
Get the highest mah and C-rate Lipo that will fit in your car. At lest 5000mah and 30 to 40 C-rate will last longer using your 4.5 BL.
If you charge at over 1-C (5 amps for a 5000) your lipo's will not last as long.
Never dis-charge cycle lipo's, theres no reason to do that with Lipo's. You have to do it with round cells to get the most from them but not lipo's.
I think most people screw up there first lipo's during practice running them to long.
I hope you have better luck with your new lipo's :thumbsup:

I was told it was probably the amp draw. I have it in a sprint and its hooked a lot of the times. It usually only uses about 1/2 the pack compacity. We only run 4 minutes sorry. I balance it once a week. I have a higher C rated lipo on the way. Hope this doesnt keep happening.

Thanks for the info guys.

5400 / 2 = 2700 in 4 minutes is about 40 amps or 7.5C average which is probably too much. Did I figure that right? :o

It's much more likely that the peak current caused the problems, not the average. If the 5400mAh battery was rated "15C", this means 81 amps maximum. A 4.5 motor could definitely pull this much from a standing start or recovery from a crash.

Wow, Im sure learning a lot here. Thanks guys
I am running a Speed Passion ESC with the 6pack resister now, but on the first lipo I was using an LRP Sphere Comp.

I don't think I saw it posted anywhere above.....

I think you should charge Lipos up (just like your were going to race) before storing them.

It is confusing as each type of battery (nicad, nimh, lipo) has different methods of care and feeding......

It's much more likely that the peak current caused the problems, not the average. If the 5400mAh battery was rated "15C", this means 81 amps maximum. A 4.5 motor could definitely pull this much from a standing start or recovery from a crash.

that is not an accurate statement. a 5400 15 c battery should hold 81 amps constant throughout the discharge. i am not saying it is a good thing to do but if the numbers are accurate those are the facts.
normally you will see a pack have two ratings like 20/30c. when they have that it means the pack should handle 20c constant and 30c for bursts usually around 10 seconds. short spike bursts are higher yet.

groundhogg....most of the manufacturers i have seen post on storing recommend storing at 50%. they say it helps keep the pack fresher but you should check it if stored for really long periods to make sure it dosent somehow discharge too low. smc specificly reccomends storing at about 50%

It's much more likely that the peak current caused the problems, not the average. If the 5400mAh battery was rated "15C", this means 81 amps maximum. A 4.5 motor could definitely pull this much from a standing start or recovery from a crash.

Yes, battery temp is the clue.

In this type of racing is there periods of off-throttle a lot? If 40 amps were an average then the peak was over 100 perhaps? There's also a good chance that the battery will not deliver 81 amps without overheating.

Yes, there is a lot of on and off-throttling.