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Old 02-22-2008, 06:21 AM   #196
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Originally Posted by syndr0me View Post
Ah, a fresh new morning. Are we ready to start fighting about batteries again?! :-D

Danny, in your disclaimer you told people not to heat the packs. That's actually something that other companies have said is "okay," and most people consider safe, so long as you don't go over the top with temperature. I think for the most part, it's considered a reasonable thing to do with your LiPos. Now, your findings of more temp = more voltage are interesting. I'm curious if the things you find will be true across the board for all brands of battery. With differences in chemistry and such, some packs may respond better (or worse) to different changes. It will be interesting to see if that's the case down the road.

So I picked up a MuchMore Battery Warming Tray a while back, and I really don't recommend it. It warms from the bottom only, and really doesn't do a very good job of getting enough heat into the pack. I'm thinking my next step might be to try a reptile heating pad ('cause they're small) and roll the battery up inside of it.

Something like this looks really nice, but they're impossible to find. I like the idea, though. You guys should OEM them... I'll be your first customer if they work well. As LiPo (and warming) become more mainstream, I imagine it's only a matter of time before we see better solutions.

Thanks for the info. I have one coming along with the optional temp control. I'll be testing this next week and may wrap it in a heating pad as well.

This weekend I'm going to Lowes to purchase some 1" aluminum strips. I'll make a "Lipo Box" with a heating pad. I'll cut the heating pad, insert the cut to length strips, and get the Wifey to sew them in place nice and pretty.lol The aluminum should hold a nice form so the pack gets an even heat spread.
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Old 02-22-2008, 08:47 AM   #197
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Tony,
In the info you posted above for Donnie, do you know what the pack temp was prior to going out. You list 204deg F as the temp coming off. That seems to me to be pretty high from what I've read and I'm just curious what kind of temp gain you were getting from the run.
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Old 02-22-2008, 10:52 AM   #198
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Tony is reffering to motor temps to show how extra voltage and lower IR from our pack increases motor temp. Everytime there is an increase in battery power the motor will need to be geared less to compensate for it.
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Old 02-22-2008, 01:05 PM   #199
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Here are my cycle numbers for the past 5-6 months. The SMC 22c 5000 was used 15 times total in a weekend for the past 5 months or so (10 practice, 3 heats, 1 practice, and the main). That's 300+/- runs and does not include all of the testing during the week. The pack may have up to 500+ cycle/runs on it to date.

October 07' (new)
12 amp charge
35 amp discharge
6.0 cut-off
sensor leads: battery side of Deans

533 runtime
7.23 voltage
11.5 IR

December 07' (3 months later)
12 amp charge
35 amp discharge
6.0 cut-off
sensor leads: battery side of Deans

505 runtime
7.28 voltage
10.2 IR

February 08' (2 months later)
12 amp charge
35 amp discharge
6.0 cut-off
sensor leads: battery side of Deans

495 runtime
7.30 voltage
9.5 IR

The batteries have held up just fine even with the overcharge that was done to them 4 times a weekend. Yes runtime is down but voltage is up and the IR's are lower. When you only race for 4-5 minutes runtime becomes less important (excluding Mod) and what the pack outputs (voltage) for 240-300 seconds is what really matter.

I think the packs are getting better with time.

Oh.......the pack above has a serious dent in the side from a 2nd weekend impact. Along with killer performance the durability factor is high as well. It literally "Took a Lick & and Kept on Tickin"
Tornado_Racing ...... Overcharging of Lipo batteries is ILLEGAL by ROAR rules. This charging practice WILL NOT BE TOLORATED at ROAR events and should not be tolerated or condoned by any track or track owner, whether a ROAR affiliate or not. If you're caught overcharging lipos at a ROAR event you will be DQ'd and sent home. No if's, and's or but's. This is a serious issue that we, ROAR, will not take lightly. Overcharging is just plain STUPID. Not only are you jeopardizing you own safety but you jeopardize everyone else's safety racing with you, traveling with you or pitting with you.
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Old 02-22-2008, 01:13 PM   #200
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Is`nt charging at a higher amp rate totally different compared to overcharging a cell ?
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Old 02-22-2008, 01:27 PM   #201
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Is`nt charging at a higher amp rate totally different compared to overcharging a cell ?
Yes, he is doing both though. High amp rate and overcharging.
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Old 02-22-2008, 04:16 PM   #202
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Overcharging is different from high rate charging. Over charging is defined as charging a battery over the max charge capacity/voltage of 8.40v (+/- 0.04V) for a 7.4v lipo. Overcharging does not happen by accident and is done intentionaly. "

"ROAR rule 8.3.1.6.2 Li-Poly batteries may be charged to a maximum of 8.40V +/-0.04V. Overcharging is a serious safety hazard and will not be tolerated."

We will be teching this at all races and anyone caught will be dealt with swiftly and harshly.
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Old 02-22-2008, 04:39 PM   #203
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Originally Posted by Thugs Bunny View Post
Tony,
In the info you posted above for Donnie, do you know what the pack temp was prior to going out. You list 204deg F as the temp coming off. That seems to me to be pretty high from what I've read and I'm just curious what kind of temp gain you were getting from the run.
My bad, as Danny posted the temp was from the motor and not the pack.
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Old 02-22-2008, 04:41 PM   #204
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Tornado_Racing ...... Overcharging of Lipo batteries is ILLEGAL by ROAR rules. This charging practice WILL NOT BE TOLORATED at ROAR events and should not be tolerated or condoned by any track or track owner, whether a ROAR affiliate or not. If you're caught overcharging lipos at a ROAR event you will be DQ'd and sent home. No if's, and's or but's. This is a serious issue that we, ROAR, will not take lightly. Overcharging is just plain STUPID. Not only are you jeopardizing you own safety but you jeopardize everyone else's safety racing with you, traveling with you or pitting with you.
WOW, please calm down. I am FULLY aware of the ROAR rules concerning Lipo's. My post was to show the durability and life span of the pack under extreme conditions including overcharging and higher "C" charge/discharge ratings.
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Old 02-22-2008, 04:52 PM   #205
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Overcharging is different from high rate charging. Over charging is defined as charging a battery over the max charge capacity/voltage of 8.40v (+/- 0.04V) for a 7.4v lipo. Overcharging does not happen by accident and is done intentionaly. "

"ROAR rule 8.3.1.6.2 Li-Poly batteries may be charged to a maximum of 8.40V +/-0.04V. Overcharging is a serious safety hazard and will not be tolerated."
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Old 02-22-2008, 05:01 PM   #206
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Tony ..... why test something that is both illegal and dangerous and then run it on the track against other racers? Even though it's inocent information to you to the next guy it may not be. When you as a racer use equipment that gives the preception of advantage you don't think other people are going to want to exploit that advantage as well? It's irresponsible and reckless and gives the lipo opponents more fuel for their fire.
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Old 02-22-2008, 05:08 PM   #207
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Tony ..... why test something that is both illegal and dangerous and then run it on the track against other racers? Even though it's inocent information to you to the next guy it may not be. When you as a racer use equipment that gives the preception of advantage you don't think other people are going to want to exploit that advantage as well? It's irresponsible and reckless and gives the lipo opponents more fuel for their fire.
To catch a thief you gotta know how to be a thief. To inform the general public IT IS HAPPENING so ALL racetracks and ROAR now know about this before it gets out of hand.

During my testing not many people (I mean VERY few) were aware of Overcharging. ROAR had not released their Lipo rules so at the time it was perfectly legal.

To my understanding there was not an Overcharging Rule until I posted how to do it on the other thread. If I am correct ROAR added the 8.44 max voltage after their Lipo rules were released.

So in a way (ROAR) your welcome as I opened their eyes to the potential problem as well. I hope you will be attending the 2008 Paved Oval Nats as I would like to meet and introduce myself.
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Old 02-22-2008, 05:20 PM   #208
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Ruben,

I am a concerned re: this high "C" charging as well, but I'm not seeing anything in Tornado's post that indicates anything outside ROAR's specific rules. If the rule is, as I read it, "no battery over 8.4v (8.44 w/tolerance) he doesn't give any specific indication he had batteries outside that.

If the INTENDED rule was "no charging at more than (some multiple of) C rating I didn't see anything concretely written. "Overcharging" is nebulous and cannot be an effectively enforced rule. "Overcharging" defined by specific voltage IS enforceable. "Overcharging" defined by a specific charging C rate IS enforceable.

Next question...and forgive me for not knowing all about LiPo...doesn't the measured no-load voltage drop significantly from what it peaks at on the charger? I know NiCd and NiMh do this and I thought LiPo did as well. If the batteries are supposed to peak at 8.4v on CCCV charge are we testing them on the charger (when they're supposed to be in their bunker)? My impression had been voltages would be tested in a pre-tech situation as the cars are ready to hit the track, but my thinking would be the voltage would be a fair bit lower than the supposed "peak". More so if the electrics are powered up. I'm wondering how far above 8.4v that battery needed to have peaked if it reads above 8.44v no-load sitting in the car.

Do we need to be more specific re: the rules we're establishing as to what is and is not acceptable?
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Old 02-22-2008, 05:24 PM   #209
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Ruben,

I am a concerned re: this high "C" charging as well, but I'm not seeing anything in Tornado's post that indicates anything outside ROAR's specific rules. If the rule is, as I read it, "no battery over 8.4v (8.44 w/tolerance) he doesn't give any specific indication he had batteries outside that.

If the INTENDED rule was "no charging at more than (some multiple of) C rating I didn't see anything concretely written. "Overcharging" is nebulous and cannot be an effectively enforced rule. "Overcharging" defined by specific voltage IS enforceable.

Next question...and forgive me for not knowing all about LiPo...doesn't the measured no-load voltage drop significantly from what it peaks at on the charger? I know NiCd and NiMh do this and I thought LiPo did as well. If the batteries are supposed to peak at 8.4v on CCCV charge are we testing them on the charger (when they're supposed to be in their bunker)? My impression had been voltages would be tested in a pre-tech situation as the cars are ready to hit the track, but my thinking would be the voltage would be a fair bit lower than the supposed "peak". More so if the electrics are powered up. I'm wondering how far above 8.4v that battery needed to have peaked if it reads above 8.44v no-load sitting in the car.

Do we need to be more specific re: the rules we're establishing as to what is and is not acceptable?
When the battery peaks on a Lipo GFX at 8.40 the voltage will drop to 8.38. Here is another thing to look at:

Charge the pack w/out sensor leads. Then hook em up when the pack is done. Voltage will read 8.53. Then discharge the pack at 35 amps down to 8.35. Let it sit for a few minutes and it will creep up to the magical ROAR 8.44.

To catch a thief you gotta know how to be a thief.
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Old 02-22-2008, 05:27 PM   #210
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Ruben,

I am a concerned re: this high "C" charging as well, but I'm not seeing anything in Tornado's post that indicates anything outside ROAR's specific rules. If the rule is, as I read it, "no battery over 8.4v (8.44 w/tolerance) he doesn't give any specific indication he had batteries outside that.

If the INTENDED rule was "no charging at more than (some multiple of) C rating I didn't see anything concretely written. "Overcharging" is nebulous and cannot be an effectively enforced rule. "Overcharging" defined by specific voltage IS enforceable. "Overcharging" defined by a specific charging C rate IS enforceable.

Next question...and forgive me for not knowing all about LiPo...doesn't the measured no-load voltage drop significantly from what it peaks at on the charger? I know NiCd and NiMh do this and I thought LiPo did as well. If the batteries are supposed to peak at 8.4v on CCCV charge are we testing them on the charger (when they're supposed to be in their bunker)? My impression had been voltages would be tested in a pre-tech situation as the cars are ready to hit the track, but my thinking would be the voltage would be a fair bit lower than the supposed "peak". More so if the electrics are powered up. I'm wondering how far above 8.4v that battery needed to have peaked if it reads above 8.44v no-load sitting in the car.

Do we need to be more specific re: the rules we're establishing as to what is and is not acceptable?
Read his post again. At the bottom he says he overcharges them (plus its carry over from another thread).

Tornado, sounds like you wont need to worry about him introducing himself. Im sure he will be watching you like a hawk

I still think its irresponsible to post this stuff.
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