LiPo temps

[drwayne]

Ive read of heating packs, starting out with temp of ~100F to optimize power availability...

But what max temp after a run is considered the limit ?

Ive noted my 6s packs start at 110F ( outside temp in AU !)

thanx

Wayne

 

[Bill-SOCAL]

When running racing we will warm our [packs to 110 as the target pre-run temperature. For sport running not always a big deal. So that starting temperature is not a worry, in fact it is perfect.

Post run you would like to see temps at 150 or less, the higher it gets the more likely it is that your packs will have issues like lost capacity, shorter life, or lowered performance.

 

[drwayne]

When running racing we will warm our [packs to 110 as the target pre-run temperature. For sport running not always a big deal. So that starting temperature is not a worry, in fact it is perfect.
Post run you would like to see temps at 150 or less, the higher it gets the more likely it is that your packs will have issues like lost capacity, shorter life, or lowered performance.

Ahh. cool ( no pun intended)

My outside temp is around 110'f so I dont bother to preheat !

I was concerned over a post run max of 68.5'C ( 155'F), but Im going to stop fretting now....

cheers

W

 

[Bill-SOCAL]

When running racing we will warm our [packs to 110 as the target pre-run temperature. For sport running not always a big deal. So that starting temperature is not a worry, in fact it is perfect.
Post run you would like to see temps at 150 or less, the higher it gets the more likely it is that your packs will have issues like lost capacity, shorter life, or lowered performance.

Ahh. cool ( no pun intended)

My outside temp is around 110'f so I dont bother to preheat !

I was concerned over a post run max of 68.5'C ( 155'F), but Im going to stop fretting now....

cheers

W

155 would be about as hard as I would push the packs regularly. Every once in a while is not going to be an issue. I shoot for staying under 140 or so if I can for normal running. Maybe prop down a bit to stay a little cooler and you will also see longer run times then too.

 

[drwayne]

155 would be about as hard as I would push the packs regularly. Every once in a while is not going to be an issue. I shoot for staying under 140 or so if I can for normal running. Maybe prop down a bit to stay a little cooler and you will also see longer run times then too.

logger claims post run of 138F and pack keeps gaining for 45 secs to 150-ish after that cutoff ( 3.4V)

used 3241/5100mAh (67%)that

sound around the mark ?

W

 

[Jim Caldwell]

Perfect, but start temp of 100 would be better.

 

[drwayne]

Perfect, but start temp of 100 would be better.

Thanks.

Id have to use an ice box to get lower than outside temps though !

We've a week of 40'c+ ( 110'F+) and probably similar for the rest of our summer ( till end March)

Logger says water tempt today was 98'F !

 

[Bill-SOCAL]

Perfect, but start temp of 100 would be better.

We've found that 110 degrees F is optimal for uses where you plan to hit the packs hard like SAWS and oval racing. For sport running anything above 80 or so would be fine. But there is nothing wrong with 110.

 

[Randy Naylor]

I like to keep my finish temps more in the 140F range, over that they have shorter life. Sorry Bill I like to be safer if possable.

 

[drwayne]

I like to keep my finish temps more in the 140F range, over that they have shorter life. Sorry Bill I like to be safer if possable.

2->3 minutes run time that takes pack from ambient and adds 40-ish 'F seems okay to this electron abuser.

very few races start with ambient 110+F.. rising packs +40 = 150F endpoint max

SAW I do not run, and 2-3 minutes runtime for SAW is unrealistic

Summertime packs usually start ~85F.. meaning a 40 increase finishes around 130 max

Summer peaks of daytime weather 110+ usually last 2-4 weeks here, else it is around 70-85

We're enduring extremes of climate North Vs South hemisphere.

Something non-economic.. more climate change !

We need more electrics, less carbon creating toys...

Hot here.. unusually so.. my ice cubes flash evaporate before landing in the glass !!!

45.8'C ( 115F ) last weekend.. 40'C 104F today at 8am

Im using the 'cool' of dawn testing

Am setting new 6s mono powerplant for this season, just checking rates.

Will setup FE rigger from BBY when it arrives. Randy stated he would/should have posted it last Tuesday, but am waiting to hear from him re confirmation.

 

[Bill-SOCAL]

I like to keep my finish temps more in the 140F range, over that they have shorter life. Sorry Bill I like to be safer if possable.

Read post #4 where I say that I target 140 as a finish temp, so I do not understand your comment. As to the starting temps I can tell you that starting at 110 does not mean they will be hotter at the end. At least not that I've seen. But the OP has little choice, he is already at 110 ambient and as long as he keeps his end temps below 150 he will be fine.

 

[drwayne]

I like to keep my finish temps more in the 140F range, over that they have shorter life. Sorry Bill I like to be safer if possable.

Read post #4 where I say that I target 140 as a finish temp, so I do not understand your comment. As to the starting temps I can tell you that starting at 110 does not mean they will be hotter at the end. At least not that I've seen. But the OP has little choice, he is already at 110 ambient and as long as he keeps his end temps below 150 he will be fine.

OP ?

 

[Bill-SOCAL]

OP ?

Original Post or Poster

 

[jayt]

It is not uncommon to see LiPos start at 75F and end up at 140F, yet start the same pack at 100F and it may only reach 130F. Why? The internal resistance at 75F is very high with most cells so when we hit them with high amp draws they heat up fast. Start them at 100F and the resistance is MUCH lower, so they heat up less with the same amp draw. The bottom line is not to exceed 145-150F after running if you want your packs to last.

The above applies to high quality packs with a burst rating about double their sustained rating. With cheap packs that have a burst that is only 10-20 amps higher than the sustained rating - all bets are off. These packs obviously have a higher internal resistance that the more costly quality packs.

.

 

[Bill-SOCAL]

There you go. Temps will rise less when the packs are warmed up prior to running and 150 is a max, 140 is a better end temperature. Kind of what I have been trying to say all along.

 

[drwayne]

There you go. Temps will rise less when the packs are warmed up prior to running and 150 is a max, 140 is a better end temperature. Kind of what I have been trying to say all along.

at 0830 this morn at ambient 84F I maxed to 114F on pack.

and then at 0900 to 117F the second pack.

probably means I could turn a larger prop, will see next oval race if I need extra speed against the 45 nitros..

( 56mph now )

Thanks for all the input.

 

[jayt]

Actually all you may need to do is start with your packs at 100F. They will deliver higher voltage right off the beach and you'll go faster with the same prop for the entire heat...

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