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Old 02-19-2008, 03:51 PM   #166
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Just because we use a manufacturer that is not Kokam, Enerland , Saehan or other mainstream manufacturers doesnt' mean that our supplier is not capacble of making some of the best Lipos. R&D and the use of the best materials is what makes a good Lipo and that is what they are doing.
Quality control, too. The role of small contaminants in LiPo should not be overlooked.
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Old 02-19-2008, 04:23 PM   #167
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Can we begin a different thread discussing ideas of making a transportable device safely heating lipos to 140? I think it would prove interesting and show the imagination of our group. Who knows, maybe it could strike you all at SMC to mass produce one depending on the ideas.
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Old 02-19-2008, 04:44 PM   #168
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I'm sure someone will slap their sticker on a reptile heating pad and charge twice as much for it.
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Old 02-19-2008, 04:54 PM   #169
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Quality control, too. The role of small contaminants in LiPo should not be overlooked.
And what exactly does the cell manufacturer have to do with "quality control"? I say absolutely NOTHING. There have been several big cell manufacturers that have had to recall or scrap production runs of cells due to quality problems.

The customer pays for tooling that's used for the product. Cheap tooling is a significant contributor to quality and not just in the battery industry. Even the "quality" manufacturers will consider soft tools for small volume applications.

Personally, I'd like to see everyone give the whole "who makes it" thing a rest. It's getting really old and gives everyone a false sense of security.

I think it's great that Danny's looking into what it takes to get performance out of his packs and sharing the results with us. I think that Danny will be the first to tell you that he doesn't have all of the answers yet but he didn't get to where he is by just blindly shoving product out the door. Battery maintenance will continue to evolve with LiPo just like it did with NiCd and NiMh.
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Old 02-19-2008, 05:08 PM   #170
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Quality control, too. The role of small contaminants in LiPo should not be overlooked.
Our supplier is doing there own QC and we have decided to cycle all our packs to make sure they meet the minimum specs and there is no issues. I believe were the first in the industry to do so and print on the packaging box.

4wd: Our first shipment will be in next Monday and it will take us a few days to get some packs cycled and out to distributors. I believe hobbyshops should be able to get them to ship from the distributors by the end of the first week of March.
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Old 02-19-2008, 05:27 PM   #171
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Can we begin a different thread discussing ideas of making a transportable device safely heating lipos to 140? I think it would prove interesting and show the imagination of our group. Who knows, maybe it could strike you all at SMC to mass produce one depending on the ideas.
I already did about a month ago. I forget the name of the thread though.
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Old 02-19-2008, 06:46 PM   #172
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China isn't exactly known as the bastion of quality manufacturing. :-D

Cycling the packs yourself is a cool idea.

I may have to buy a Turbo 35 VCR so I do some testing of my own.
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Old 02-19-2008, 09:07 PM   #173
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LOL... I have lipo "ovens" already. I've used a crude one for the last couple years. Now I've been working on a nicer one that's marketable. There might even be a couple of them at the Chi Town Shootout next week. I suspect we will see a few such devices on the market eventually.

IMO these should always be used when racing in cold environments like some of us have in the winter... whether outside or an indoor track where it's hat and gloves temp. You should keep lipos at least at a nice room temp, and @100 degrees makes a noticeable difference over room temp. But now the hardcore racers will want to use them all the time to get them to 120-140 etc to get even better performance.

For a long time, warm lipos was a little secret some of us knew about. Now everyone will know. Thanks Danny, I think... lol

Discharge graphs have shown for years (like found on rcgroups.com) that voltage (performance) is directly related to temperature. Hot batteries always work better and lipos are no different.

Hopefully this will put and end to guys intentionally overcharging lipos, and pumping huge amps into them, etc... thinking it's the magic bullet.

So SMC gets two thumbs up from me.
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Old 02-19-2008, 09:08 PM   #174
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Darn slow site... oops.

Last edited by glassdoctor; 02-19-2008 at 09:18 PM.
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Old 02-19-2008, 09:50 PM   #175
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Please don't attempt any of the tests I'm performing or use a charge rate higher than 1C. Never warmup your Lipo packs. Doing any of this can result in fire and can be dangerous

In my own testing I finding out that charging at 12 amps is giving better results than charging at 5 amps. That is with cold packs.

The test that really surprised me was a back to back cycle but using 5 amps on the second one which the pack was at 144 prior to the start and when it was done the numbers weren't better than a regular 5 amp cycle on a cool pack.

My next test will be to fully charge a pack when it's cool at 5 amps then warm it up to 140 degrees to see if it gives me the same good results as charging at 12 amps on a pack that is 140 degrees or so.

Here is some info I have on how our manufacturer tests for high temperature swelling. This might be interesting to some of you.

2.3 High Temperature Swelling
Test method: Cell (rated charged) is exposed to 80℃ for 4hours.
Measure thickness right after swelling test and the recovered capacity by
rated charge/discharge cycling after rated discharging(7mA, 2.75V cut-
off) at 25℃.


Criteria: No leakage, Cell thickness < 5.5mm,
Recovery > 126mAh (90% of the rated discharge capacity)
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Old 02-19-2008, 10:04 PM   #176
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China isn't exactly known as the bastion of quality manufacturing. :-D
...and Korea is?
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Old 02-19-2008, 10:33 PM   #177
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http://xkcd.com/386/
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Old 02-19-2008, 10:44 PM   #178
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LOL, too funny, I have to add that to my collection.
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Old 02-20-2008, 12:50 AM   #179
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I've used tire warmers (the wrap around type) on my lipos before to keep them warm in cold weather. I plugged the warmers directly up to my 12v power supply. Just wrap them around the lipos. I thought they get upwards to around 180 (the inside of the warmers). But I'll have to measure that again when I get a new temp gauge. I accidentally left my gauge in my jeans. And well... the washing machine took care of that for me...
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Old 02-20-2008, 12:52 AM   #180
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...and Korea is?
Yes... perhaps you came from the year 1950 via a time machine?
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