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Old 12-01-2008, 11:53 AM   #1456
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If you show up to tech above the limit you're sitting the run out. There's not "do overs" in tech.

Here's an idea for big races that use a spec item: How about handout batteries- pre-charged! It'd be a bit of a load keeping batteries charged but you wouldn't need one battery for each racer, they could be on rotation. This would probably only be good for the lower amp-draw classes.
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Old 12-01-2008, 11:57 AM   #1457
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Originally Posted by Davidka View Post
If you show up to tech above the limit you're sitting the run out. There's not "do overs" in tech.

Here's an idea for big races that use a spec item: How about handout batteries- pre-charged! It'd be a bit of a load keeping batteries charged but you wouldn't need one battery for each racer, they could be on rotation. This would probably only be good for the lower amp-draw classes.
I remember the rules at the IIC this year was...the tech checked temp and voltage, and just told you if you passed or not, but you were not told what your voltage of temperature were. If you didn't pass, you were to go back to the end of the line for tech and try again, until you passed. If this didn't happen before the run started, then yes, you were SOL.
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Old 12-01-2008, 12:31 PM   #1458
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I didn't know they were doing that. I think a "one shot" policyis necessary to prevent people from overcharging. They won't do it if they know they'll miss their run. Allowing them to come back around doesn't really address the safety, not performance, issue that the rule is designed to prevent.
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Old 12-01-2008, 12:33 PM   #1459
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I didn't know they were doing that. I think a "one shot" policyis necessary to prevent people from overcharging. They won't do it if they know they'll miss their run. Allowing them to come back around doesn't really address the safety, not performance, issue that the rule is designed to prevent.
Not all chargers or voltmeters are created equal.. My orion reads 8.41, but on a Fluke reads 8.37, could easily go the other way.
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Old 12-01-2008, 12:36 PM   #1460
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That's a variance but your charger still doesn't appear to be overcharging. If somebody's fluke resulted in a 8.48 voltage, then the charger is not made to the safety standard it should've been and it should no longer be used. Teching for voltage is a way to weed out those things. It doesn't even matter if the overcharging was intentional or not, it's the responsibility of the racer to abide by the rules and to be sure that their gear does too.
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Old 12-01-2008, 12:41 PM   #1461
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well put!
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Old 12-01-2008, 01:06 PM   #1462
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Originally Posted by Davidka View Post
I didn't know they were doing that. I think a "one shot" policyis necessary to prevent people from overcharging. They won't do it if they know they'll miss their run. Allowing them to come back around doesn't really address the safety, not performance, issue that the rule is designed to prevent.
This will be EFRA's LiPo policy in 2009. But instead of losing your run you will be disqualified from the event.
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Old 12-01-2008, 01:17 PM   #1463
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Originally Posted by Davidka View Post
I didn't know they were doing that. I think a "one shot" policyis necessary to prevent people from overcharging. They won't do it if they know they'll miss their run. Allowing them to come back around doesn't really address the safety, not performance, issue that the rule is designed to prevent.
I think the rule was being treated as a way to weed out chargers out of calibration more than trying to weed out people attempting to cheat, or push the boundaries.
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Old 12-01-2008, 01:20 PM   #1464
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This will be EFRA's LiPo policy in 2009. But instead of losing your run you will be disqualified from the event.
I like this idea. I hope ROAR takes notice, because their current rules are beginning to be abused.
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Old 12-01-2008, 01:35 PM   #1465
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I think it was exactly the opposite (the reason for teching voltage). But either way, it's an important thing to police. Mkint one shot will guarantee that racers will check their gear at home and be sure that their chargers are calibrated right. Things like the LRP charger coming out with a voltage adjustable voltage threshold are dangerous. LiPo battery chemistry isn't flexible (correct me if that's wrong), 8.4v is the cieling for safety, isn't it?
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Old 12-01-2008, 01:50 PM   #1466
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its going to come down to you are going to have to go up during practice and compare your charger to the voltmeter being used at tech and see where it falls, just like you don't depend on your scale at home for car weight, i'd hope you would weigh your car on the tech scale when you practice, get there and just do the same with the tech voltmeter, now thinking about it CE should make the peak adjustable to allow for this "self teching", not a massive range but 8.30 to 8.50 volt maybe
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Old 12-01-2008, 02:08 PM   #1467
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I don't want to encourage overcharging but if you think that it's a saftey issue that a charger overcharges a pack by .08 which equals to .04 per cell then your way to freaked out about Lipos. The standard is to charge at 4.2 per cell but there is a margin of error with these packs. The cell will not catch on fire if it goes to 4.24 or even a bit higher. ROAR does overcharging tests and apporved packs will withstand some oevrcharging.
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Old 12-01-2008, 02:10 PM   #1468
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Man! If you volt meter is that far off .. get a new one or replace the battery!
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Old 12-01-2008, 02:18 PM   #1469
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Originally Posted by mojoman View Post
I just wanted to know if I could send my GFX back? I didn't mean to start a riot about the rules ROAR has already laid down.

John St.Amant my parents used to tell me....."if you don't have anything nice to say don't say it at all". Please show Danny/SMC and this thread some respect as they are here for customer support and to help guys out that use or are planning to use their product. The man knows a lot more about battery technology then you, as proven by your recent posts. So if you have something productive to add feel free...................

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I've fit one of these new packs in my 12R5 and the wires come out right where my GTB-4 is. And It's not pretty. Looping Wires all over or hanging them off my chassis isn't my style. And I don't disrespect anyone here or anywhere actually. Seems to me every other manufacturer is using the barrel connectors. So why does SMC have to be difficult !? Remember all the different connectors on servos and speedos we used to have to get the right ends on to plug in to our recievers ? Now everyone is using a derivative of the Futaba "F" connector. Universal connectivity ! It's a beautiful thing!
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Old 12-01-2008, 02:21 PM   #1470
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Originally Posted by Danny/SMC View Post
I don't want to encourage overcharging but if you think that it's a saftey issue that a charger overcharges a pack by .08 which equals to .04 per cell then your way to freaked out about Lipos. The standard is to charge at 4.2 per cell but there is a margin of error with these packs. The cell will not catch on fire if it goes to 4.24 or even a bit higher. ROAR does overcharging tests and apporved packs will withstand some oevrcharging.
Quote:
2. OVERCHARGE – LiPos are extremely non tolerant to an overcharge condition. A standard charge profile is CC/CV to 4.200V. Drastically overcharging a cell just once is a sure way to send a cell into thermal runaway. Overcharging a cell slightly but repeatedly is also extremely bad for a cell. For example, it you charge a cell to 4.300V, the lithium ions start plating on the electrodes forming lithium metal. Lithium ions are not flammable, but lithium metal is. Every slight overcharge cycle will plate more and more lithium metal resulting in a battery that is very prone to igniting.
I think the main concern is with repeated slight overcharging. Maybe the margin of error there is still safe. Dunno for sure. It's sketchy as hell to test it, though.

http://www.rctech.net/forum/electric...res-101-a.html
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