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Old Nov 14, 2013, 07:48 PM
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Joined Feb 2012
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Help!
Just NEED some reassurance

I have a 12S battery pack, which in actuality is 2-6S batteries shrink wrapped together (I have to charge them on two separate ports). I recently started flying my TREX 700E again and I have a thunder power (TP820CD) charger. here is the link to the battery:

http://hobbyking.com/hobbyking/store...arehouse_.html

Can someone please tell me what I can safely charge these bad boys at (IN AMPS)? I just don't want to have this thing blow up. I have been charging them at 2 AMP, just to get them used to it again. but if I was in a hurry, what is the maximum charge rate I can charge each battery pack at??

Thank you for your help in advance, I promise I will reply and thank you personally when I get the chance and log back in.
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Old Nov 14, 2013, 08:30 PM
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United States, FL, Palm Coast
Joined Mar 2012
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Quote:
Originally Posted by Theace115 View Post
I have a 12S battery pack, which in actuality is 2-6S batteries shrink wrapped together (I have to charge them on two separate ports). I recently started flying my TREX 700E again and I have a thunder power (TP820CD) charger. here is the link to the battery:

http://hobbyking.com/hobbyking/store...arehouse_.html

Can someone please tell me what I can safely charge these bad boys at (IN AMPS)? I just don't want to have this thing blow up. I have been charging them at 2 AMP, just to get them used to it again. but if I was in a hurry, what is the maximum charge rate I can charge each battery pack at??

Thank you for your help in advance, I promise I will reply and thank you personally when I get the chance and log back in.
I don't know exactly about those A-spec packs. But the regular Turnigy Nano 5000 mAh 6S packs i bought a few months back said 8C on the back i think. So that would mean 8x the capacity.

"Normal" charging would be 1C. So 1X the capacity. 5000 mAh at 1C charge would be 5A. So if the back of your pack has a max C charge rating listed, go by that. But say it was 8C. 5000 mAh @ 8C charge would be 40A.

Make sense?


Something interesting i want to mention. I recently bought 3, 4000 mAh, 35C nano packs. None of the 3 had a Max C charge listed on the back like all of my previous packs did. Not sure why that is. I also noticed my two 5300 mAh 45C Gens Ace packs that i received the same day didn't have a rating listed on the back either. But those were my first Gens Ace packs. I was under the impression that they used to list max charge rating on the back also. Kind of strange. Perhaps they stopped doing it because of liability or something.
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Old Nov 14, 2013, 08:39 PM
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Reply to integrity handywork

yes that does make sense, that just seems like a massive amount of juice, so that is also taking into account that these are 2 separate batteries and theyre is a wire I have to hook up for a series circuit. when I go to charge them, I basically have to unhook the series connection, hook each side up to the charger, then attach the balancing ports. so you think I can run 80 amps through my charger and charge each battery at 40 amps? again I am just being careful, I am not questioning your math. I may just need to do research and be sure as to what my charge rate is for those.
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Old Nov 14, 2013, 09:08 PM
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Originally Posted by Theace115 View Post
yes that does make sense, that just seems like a massive amount of juice, so that is also taking into account that these are 2 separate batteries and theyre is a wire I have to hook up for a series circuit. when I go to charge them, I basically have to unhook the series connection, hook each side up to the charger, then attach the balancing ports. so you think I can run 80 amps through my charger and charge each battery at 40 amps? again I am just being careful, I am not questioning your math. I may just need to do research and be sure as to what my charge rate is for those.
No, I really doubt your charger can output 80A. Hell i doubt it can even output 40A. Most chargers can't unless you paid hundreds for them. A 1000W charger is capable of approx. 30A @ 6S. I just looked back at the charger you are using. It's a nice 2 port charger. But it has a 20A per "port" limit. So you should be fairly safe to crank it to 20A per pack/port. That would be 4C charging each 6S pack. 4C or 5C seem to be what Gens Ace recommends for their packs. But like i said, refer to the number on the back of your pack, if there is one.

You are correct. These are massive amounts of current and you really do need to be safe. Anything above 15A and you will need some beefy wires, like 12 AWG or fatter. I would prefer to say 10 AWG or fatter actually. I was assuming you had to charge that 12S pack as two separate 6S packs, and was speaking in such terms. I was speaking in basic charging practice. The normal would be 1C. So a 5000 mAh pack can "Safely" be charged at 5A. if your pack said Max 8C on the back you can multiply 5Ax8C for the max current in amps you can set your charger to, according to the manufacturer's "safe max" limit.

The important thing to remember is that you should always keep an eye on your packs. Make sure they don't get warm when charging. They might get a little warm at high C charging, but they shouldn't get too warm. Cool to the touch is best when charging. Especially after flying your packs. It's always safer to charge at lower currents. Charging at higher currents could degrade the cells quicker, which is a subject of much debate in the community. However everyone agrees that high C charging is not as safe and you should be more careful when doing so.
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Old Nov 14, 2013, 09:17 PM
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Also, this web site has a very in depth explanation of lipo batteries, chargers and all kinds of other info about learning to fly and everything. It's a pretty good information source i have referred to often. If you read though or search though. You should find lots of answers when it comes to the math and everything else.


http://www.rchelicopterfun.com/rc-lipo-batteries.html
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Old Nov 15, 2013, 11:23 PM
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I charge at 0.8C on 5Ah non-paralleled using several chargers . 1.5 to 2C on the smaller packs I have a enough cheaper packs for each heli for a day of flying.

I feel quite a bit safer with non-parallel charging even though I'm in the same room (albeit for 70-80 min or so). Throwing it out the window, a 6S 5Ah going off in my dense community would have the cops and fire trucks around in minutes.
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Old Nov 16, 2013, 08:30 AM
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I charge at 0.8C on 5Ah non-paralleled using several chargers . 1.5 to 2C on the smaller packs I have a enough cheaper packs for each heli for a day of flying.

I feel quite a bit safer with non-parallel charging even though I'm in the same room (albeit for 70-80 min or so). Throwing it out the window, a 6S 5Ah going off in my dense community would have the cops and fire trucks around in minutes.
I actually bought a few 4X6S chargers because it seemed safer than para or series charging. Though the charger's limits are 200W and 400W. So the MAX i can output per channel @ 6S on the 400W one is ~4.4A. That is all well and good for my 3S packs or my 4000 mAh 6S packs. But my 700 flies bigger 5000 and 5300 mAh packs. So i bought a 1000w Volts 101K charger for $149 shipped at readyheli.com and i now charge two 5000 or 5300 mAh packs in parallel at 20-30A. 30A works out to about 3C charging because of the parallel connection. Depending on if I'm at home or at the field. I might just do 10A which is a 1C charge. Either way i can charge 10,000+ mAh worth of 6S packs in about 30-40 minutes or so. It wouldn't go quite as fast only charging them at ~4A each. Which is less than 1C.

The Thunder power 2 port charger he has says it has a 20A limit per port. But all that could mean is it won't go past 20A period. Not for 6S, not for 10S, and most certainly not for 2S or 3S. But the charger it's self has a 800w limit. That 800 watts is divided between two chargers or "ports". So in reality the MAX amperage he can charge per port is going to be less than 20A @ 25.2V or 6S. The equation to know what the max amount of amperage the charger can output based on the wattage of the charger is: Wattage / Voltage = Amperage.

So his thunder power 2 port charger, in theory, should only be able to charge ~15.8A at 25.2v or 6S according to the math. ( 400w / 25.2V = ~15.8)

The messed up thing for me is that the Voltz 101K that i bought is basically a licensed "clone" of the iCharger 3010B 10S charger. It only costs $149 and has a 1000W output capacity, internal resistance meter and some other features. But only one output "port". While my 4X6S chargers cost me around $130 each and something like $20 for shipping from hobbyking and they aren't anywhere near as good except for the feature of having the power output distributed to 4 chargers or "ports". I think Voltz will be the chargers i buy from now on because the Hobbyking/Turnigy 4x6S chargers have all needed me to repair them on multiple occasions. Bad solder joints, cold joints, burned out cooling fans, and burned up components. Not worth the price.
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Old Nov 18, 2013, 12:16 PM
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Thank you for all your advice and information.... I did some research and turnigy claimed that the can be charged up to 15C fast charge capability.... so with my charger.... balance charging (2) 6s batteries on two separate ports, what is the max amperage charge rate yall would recommend in AMPS per a battery??? 15 amps? thank you again.
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Old Nov 18, 2013, 05:17 PM
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15C x 5000ma/h = 75000mA charge current = 75A at 24V = 1800W of power
Yes, that is crazy. At 15C charge rate It would be full in just 4 minutes, but it won't, because the last part of the charge the voltage has to be limited to stay under 4,20V per cell and the charge current starts to drop off gradually. This extends the time before the pack is full. The Quick chargew option on the charger just cuts off a part of the end, so it will not be completely charged. Might take a minute or so off your flight time, perhaps less.

But your original post about reassurance....
Does charging faster than you can empty the lipo in flight, sound like healthy to your battery?
Guess not. I think it is better to aim for something more reasonable, say your flying 8 minutes while the other pack is charging, take 5 minutes break after that you lipo should be full in 13 minutes. That would be about a 5C charge rate, so 5C x 5000mA/h = 25A charge current.
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Old Nov 18, 2013, 07:33 PM
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Quote:
Originally Posted by Theace115 View Post
Thank you for all your advice and information.... I did some research and turnigy claimed that the can be charged up to 15C fast charge capability.... so with my charger.... balance charging (2) 6s batteries on two separate ports, what is the max amperage charge rate yall would recommend in AMPS per a battery??? 15 amps? thank you again.
like i said before. Your charger is not capable of more than 20A per "port" at it's MAX for ANY voltage. Being a 800W / 2 port charger. At 25.2V your charger will likely only be able to pump out ~15.9A per port. Just so you can follow the math it's 800W divided by 25.2 volts divided by 2 ports = ~15.9A per port @ 25.2v.

If you max your charger out and it doesn't run hot, your good to push the max. But if things run hot you risk reducing the life span of either your charger or your power supply. Which ever one is running hot. If your power supply is supplying the max voltage your charger will allow (usually 24V). Chances are your charger is going to run pretty cool with a 24V supply. But if your supplying 12V and your charger is working to up convert voltage from 12V to 25V, your charger might run hot. if you max out the amperage that your PSU can supply, it will likely run hot as well. So the question becomes whether or not your PSU can handle the load. Technically speaking you would need at least a 800W PSU that supplies 24V or whatever the max input of your charger is. But i would recommend a 1000W or 1200W PSU for head room, so that your not maxing the PSU out completely while maxing out your charger. .

15 amps on a 6S 5000 mAh pack would be 3C. Which is plenty IMO. If the max for those packs you have is 15C, you'll never be able to accomplish that. I don't think the most expensive chargers and PSUs on the market can accomplish a 75A charge. Even if they could i would have to charge the packs in a bomb bunker because i would just expect them to explode. So that 15C number really doesn't sound right to me. But, In all technicality you should be "safe" to max out each port as long as your equipment isn't burning up in doing so. Just make sure you use at least 14 AWG (gauge) wire for your charge leads coming out of your charger so the wire doesn't get hot. 10 AWG if you have to buy new wire anyway. Nothing wrong with having some extra head room on the wires too.

In my opinion, if your at home charging the night before flying just use 1C charge @ 5A per 6S pack/port. No point in rushing a charge if your not going to fly it right away when it's done. I like to 1/2C charge @ 2.5A sometimes when i'm at home. They seem to accept a charge and balance better at low C charging. Lots of people feel that high C charging degrades your packs quicker. Regardless of if it does or not. It is still more dangerous and you should monitor the packs and even go over and feel them every now and then to make sure they aren't getting warm while charging.
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Old Nov 18, 2013, 10:12 PM
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I want to thank IntegrityHandywrk, Sp00fman, and Eagle777 for all of your help. this information all helped me to understand my batteries better. and I now feel safe charging them at a high C rate. I probably will not go over 10 Amps ever. Btw, my power Supply is a 1080 WATT, Max 18 Volt, and Max 60 AMP. I should be able to charge at 10 AMPS with no repercussions, like over heating or Thermal runaway with my batteries... hopefully next question I ever have to post, it will be answered to the depth and precision you guys answered . Thank Yall Again
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