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Old 07-22-2014, 09:18 AM   #16
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Originally Posted by xevias View Post
With this said, an overcharged battery will give you virtually no advantage if you scrape a board once or twice during a run. So really the best feature of having an iCharger is to protect your batteries. Not to go faster.


I'd only add that my 4010 duo and my Powerlab 8 seem to be more accurate and charge faster than other chargers that I have tried.

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Originally Posted by Pauly6401 View Post
I hope this is true. LiPos were supposed to do away with all the crazy battery tricks we lived with during NiMhs, like cycling, heating, overcharging, etc. I don't want to get back into that world again!
Sadly, I believe that people will always push the envelope so long as Spec classes dominate the racing scene.
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Old 07-22-2014, 09:31 AM   #17
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I did a lot of research on how to charge batteries when I decided to buy a 308Duo. This is what I learned:

Almost everyone (blinky racers) over charges their batteries to hit the ROAR voltage limit of 8.44v. ROAR uses this limit to take into account small variances in measuring devices. However, everyone upped their battery voltage to take advantage. The limit really should be 8.4v, period.

People are over charging at high amps with cycling to time the heat buildup in the battery with their race. Heat in the battery lowers IR providing the motor with higher voltage. This, evidently, has replaced the now illegal LiPo battery warming trays.

The iCharger has a couple features that can help you do the above a little bit safer. Or these features can charge the batteries more efficiently (if you choose the safer, lower voltage charge levels).

One is the iCharger balancing options. You can program this to death to get the best charge time while keeping your cells' IR matched and increasing battery efficiency and service life.

It also has the option to 'trickle' charge the battery after it has completed to maintain the 4.2v per cell as you get ready to race.

With this said, an overcharged battery will give you virtually no advantage if you scrape a board once or twice during a run. So really the best feature of having an iCharger is to protect your batteries. Not to go faster.
The ROAR limit is 8.4.
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Old 07-22-2014, 09:39 AM   #18
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A guy at our local track said iCharger makes a huge difference in power and speed. To me, it doesn't make sense because even if it charges up to 20A whatever, once it's charged it charged, right?
Can somebody explain how it makes the car faster and more powerful if it ever does it?
The basic idea is that you can use the high charge and discharge rates to increase the core temperature of the battery which will lower internal resistance and make the car faster.

If you were to take a heating pad and warm your battery, you would notice the same increase in performance. But to prevent people from going crazy with temps most big races have set a max temp limit and they strictly prohibit warming. Some even limit max charge rates (unenforceable however). These chargers circumvent the no warming rules.

Some budget ways to heat batteries are to place your battery on your power supply or place the battery in a warm place. What really matters is the temp of the battery when teched (if there is tech). the most basic way to increase core temp is to use the same battery throughout the race day.

Now at club races no body really cares or checks temps, voltage,or anything so guys overcharge their batteries to 8.50, warm the packs, run illegal motors, etc. to go faster. Stock racing is pretty much the wild west with limited or no rules at the lower levels.

You are right though; if you were to charge your battery with an iCharger at 10A and charge the same battery on another charger at 10A, there will be no difference in how they perform assuming both batteries end at the same voltage and same temperature.
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Last edited by Rick Hohwart; 07-22-2014 at 11:19 AM.
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Old 07-22-2014, 10:45 AM   #19
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I like the iCharger as it seems more accurate and consistent than my old TP820CD. I normally charge at 10-12 amps. Only because of time constraints not to heat my pack.
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Old 07-22-2014, 10:55 AM   #20
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We tech packs based on the outside temp of the case they're in. If you heat them from the outside in (using a heating pad) the outside of the case will have the highest temp. If you do it with discharge, it heats from the inside out, so the inside of the pack has the highest temp. You could, in theory, get more heat in the pack (lowering its IR) and still pass tech.
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Old 07-22-2014, 01:31 PM   #21
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I nearly got DQd at the TCS regional because I accidentally left the battery in the sun. Dunno if the internal temps went up, but the case was right there!

I had a Thunderpower which I loved, but I love my iCharger more. If you get behind being able to get charged in time is a plus, the menus are easier than the TP to navigate. I usually charge at 10a, sometimes more.
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Old 07-22-2014, 01:40 PM   #22
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I like my Graupner EX.. also like the knockoff Reaktor (clone Icharger208) Both do a great job and I can get almost 135 more watts from them compared to my other chargers..So Yes The Icharger is that much better
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Old 07-22-2014, 02:25 PM   #23
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I have no complaints about the iCharger series, specifically the 308, 406 and 4010. My 4010 has been quick charging, accurate (as far as I can tell) and can be updated. If you don't want to spend the money on the upper end of the iCharger series, they have less expensive options. Best place to get either the iCharger or Powerlab is here:

http://www.progressiverc.com/
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Old 07-22-2014, 02:33 PM   #24
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Quote:
Originally Posted by Rick Hohwart View Post
The basic idea is that you can use the high charge and discharge rates to increase the core temperature of the battery which will lower internal resistance and make the car faster.

If you were to take a heating pad and warm your battery, you would notice the same increase in performance. But to prevent people from going crazy with temps most big races have set a max temp limit and they strictly prohibit warming. Some even limit max charge rates (unenforceable however). These chargers circumvent the no warming rules.

Some budget ways to heat batteries are to place your battery on your power supply or place the battery in a warm place. What really matters is the temp of the battery when teched (if there is tech). the most basic way to increase core temp is to use the same battery throughout the race day.

Now at club races no body really cares or checks temps, voltage,or anything so guys overcharge their batteries to 8.50, warm the packs, run illegal motors, etc. to go faster. Stock racing is pretty much the wild west with limited or no rules at the lower levels.

You are right though; if you were to charge your battery with an iCharger at 10A and charge the same battery on another charger at 10A, there will be no difference in how they perform assuming both batteries end at the same voltage and same temperature.


This integy box is $30 and dumps batteries @ 30A. You can take a normal charger and after the charge is over, hit it with 30A for a couple minutes until it warms up and charge it again. The internals will be hot just like the $400 charger.
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Old 07-22-2014, 02:43 PM   #25
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This integy box is $30 and dumps batteries @ 30A. You can take a normal charger and after the charge is over, hit it with 30A for a couple minutes until it warms up and charge it again. The internals will be hot just like the $400 charger.
That will work!
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Old 07-22-2014, 02:57 PM   #26
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Originally Posted by syndr0me View Post
We tech packs based on the outside temp of the case they're in. If you heat them from the outside in (using a heating pad) the outside of the case will have the highest temp. If you do it with discharge, it heats from the inside out, so the inside of the pack has the highest temp. You could, in theory, get more heat in the pack (lowering its IR) and still pass tech.
So the trick you're saying to understand correctly, is that you discharge the pack to raise core temp and then charge it again normally. Then still outside temp will be normal yet you'll get more performance from the pack due to the heat generated from discharging. Correct me if I'm wrong.

2nd question is, if you raise the battery temp with however method, would it last for a while? Rick above mentions that it'd be better to use same battery all day. My understanding on that is the high battery temp from previous usage will last for a while then. This brings me to the question "Why do we need to cool down the battery before charging it again if high inner temp is better?". At least that is my understanding in order to prevent the puffing and lengthen the life of the battery.
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Last edited by snuvet75; 07-22-2014 at 03:08 PM.
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Old 07-22-2014, 03:03 PM   #27
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Originally Posted by Rick Hohwart View Post
The basic idea is that you can use the high charge and discharge rates to increase the core temperature of the battery which will lower internal resistance and make the car faster.

If you were to take a heating pad and warm your battery, you would notice the same increase in performance. But to prevent people from going crazy with temps most big races have set a max temp limit and they strictly prohibit warming. Some even limit max charge rates (unenforceable however). These chargers circumvent the no warming rules.

Some budget ways to heat batteries are to place your battery on your power supply or place the battery in a warm place. What really matters is the temp of the battery when teched (if there is tech). the most basic way to increase core temp is to use the same battery throughout the race day.

Now at club races no body really cares or checks temps, voltage,or anything so guys overcharge their batteries to 8.50, warm the packs, run illegal motors, etc. to go faster. Stock racing is pretty much the wild west with limited or no rules at the lower levels.

You are right though; if you were to charge your battery with an iCharger at 10A and charge the same battery on another charger at 10A, there will be no difference in how they perform assuming both batteries end at the same voltage and same temperature.
Higher charge rate -> increase temp ->lower IR -> faster. Ok I get that. But how does it translate into overcharging?? Lowering IR allows you to overcharge the battery? I don't know much about iCharger but both of mine only charge up to 8.4V (2S pack). Both charge at 6A maximum. Does the screen on the charger say over 4.2V each cell when you overcharge it?
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Old 07-22-2014, 03:07 PM   #28
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The last time I was seriously into RC, the rule of thumb was that you don't want to charge your Lipos at greater than a 1C rate (3000 mAh = 3A, etc). This was to avoid damaging the cells, and the possibility of fire/explosion.

Has battery technology improved to the point where this is no longer the rule, or has conventional wisdom changed and people just do what they want? I have an old Team Checkpoint charger that can charge at a 10A rate, so I'm not sure what you are necessarily gaining from a 30A charge rate, other than time (and the heat mentioned above).
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Old 07-22-2014, 03:10 PM   #29
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Originally Posted by snuvet75 View Post
Higher charge rate -> increase temp ->lower IR -> faster. Ok I get that. But how does it translate into overcharging?? Lowering IR allows you to overcharge the battery? I don't know much about iCharger but both of mine only charge up to 8.4V (2S pack). Both charge at 6A maximum. Does the screen on the charger say over 4.2V each cell when you overcharge it?
The 308, 406 & 4010 allow you set per cell peak voltage. So I could set it at 4.22 or 4.23 etc per cell to get to 8.44 / 8.46 as a pack respectively. The high discharge rate is what creates the heat, the high charge rate keeps the heat in while ensuring your pack charges quick to be able to take advantage of the heat/lower ir. The more you cycle a pack this way on a race day the lower the ir becomes.
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Old 07-22-2014, 03:31 PM   #30
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The 308, 406 & 4010 allow you set per cell peak voltage. So I could set it at 4.22 or 4.23 etc per cell to get to 8.44 / 8.46 as a pack respectively. The high discharge rate is what creates the heat, the high charge rate keeps the heat in while ensuring your pack charges quick to be able to take advantage of the heat/lower ir. The more you cycle a pack this way on a race day the lower the ir becomes.
Thanks. Man this helps a lot. So every time you use a pack, do you cycle (discharge/charge) it again? What voltage do you discharge it to? And if you know how long typically a cycle takes, would you want to finish charging the battery right before the race or does it not matter?
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