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Old Jan 30, 2013, 11:10 AM
KDS450QS(ZYX4),V977,CX-20
FyreSG's Avatar
United States, CA, Monterey
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How do charge 2 x 18650 (series)?

I bought a Turnigy 9X transmitter from someone, who gave me a DIY battery pack. He soldered two pieces of 18650 Lithium Ion battery in series to form a 2S pack, and soldered two wires at each terminal to a plastic connector for plugging into the transmitter. The battery pack did not come with a balance lead.

I have a Accucell-6 (similar to IMAX B6 and clones). How do charge this battery pack with my Accucell-6? Do I use charge it with the "LiPo Batt" Program? Do I have to add on a balance lead, or are there easier ways?

Thanks.
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Old Jan 30, 2013, 11:27 AM
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Highly recommended that you add a balance lead. I personally will never charge any lithium based series battery pack that does not have provisions to monitor voltage of each individual cell.

That said, you can simply charge on 2S normal charge (non-balance) setting. Need more details on the specific cells to determine appropriate LiXX setting as diffferent cells have different termination voltage.

Mark
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Old Jan 30, 2013, 12:00 PM
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Most sites list the 18650 battery as a 3.7v nominal battery so in theory Lipo setting.

However that's a pretty low voltage for that TX so you'll probably be charging it a lot. You might want to look into a 3-cell LIFE pack. There's tons of info out there on the 9x.
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Old Jan 30, 2013, 05:03 PM
Mosquito 6
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Originally Posted by grimbeaver View Post
Most sites list the 18650 battery as a 3.7v nominal battery so in theory Lipo setting.

However that's a pretty low voltage for that TX so you'll probably be charging it a lot. You might want to look into a 3-cell LIFE pack. There's tons of info out there on the 9x.
As I recall, the 18650's are LiFeP04 chemistry, so the settings will be signifigantly different, especially charge and discharge rate. If you're committed to using 18650's, the 3,400 mAh Sanyo's should come out in April. Even as safe as they are, I would echo using balance leads, as well as the caveate regarding tx voltage. You gotta have the "headroom" voltage to keep the tx Vreg turned on .. probably at least 5.25 vdc. Some 18650's have built in protection circuity, just like a LiPo, so if one in series hits LVCO, your tx is Off

I too recommend using a 3S LiFe .. the Zippy 1,8000 mAh 3S 5C fits perfectly into a T9X .. purpose designed just for Tx power. You may have to modify either the battery connector for your tx or the battery leads, or make an adapter .. no biggie
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Old Jan 30, 2013, 05:14 PM
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+1 on the 1800 zippy transmitter life pack !!!!!!!!!!!! been using it for 2 yrs now and i fly "in season" allmost every day but i charge it about once a month in my dx7. voltage starts out at 10.2 or so .... quickly drops to 9.9 and just stays there!!!!!!!!!!! and it doesn't lose it's charge. And if i can't remember when the last time i charged it, I charge it..... doesn't hurt a thing to put in only a couple hundred mah's.... Allways balance charge and Allways use a life charger.
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Old Jan 30, 2013, 07:56 PM
KDS450QS(ZYX4),V977,CX-20
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Thanks for your inputs! I'm using this battery pack because it came with the TX. It has served the previous 9X owner very well so I thought of continue using it. I've thought about getting a TX battery pack but it's hard to justify getting one when the current one is working perfectly.

I have another question. Please refer to the diagram of the 2 x 18650 (series) battery pack below:
Code:
_________(plug)
^ |
| |
| |
| v
---
The 2 batteries are soldered in series. Is it possible to charge one battery at a time, while they being soldered in series? Perhaps connecting the positive and negative terminals of one battery to charge, then when that's done, charge the next battery the same way? Sorry if this is a dumb idea.
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Old Jan 30, 2013, 08:04 PM
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Originally Posted by TayNinh68 View Post
As I recall, the 18650's are LiFeP04 chemistry, so the settings will be signifigantly different, especially charge and discharge rate.
Nope, standard 18650s are LiIon, 4.2V peak cells. Charge them on the LiPo setting, but at no more than 1C for safety.

You need a balance lead, or use a cell holder so you can charge in parallel (what I do for my torches). You can probably charge protected cells without a balance tap, but they will eventually become un-balanced and will then not charge properly until you correct it. Best to have a tap from the start.
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Old Jan 31, 2013, 06:53 AM
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A lot of confusion here.
18650 donates the type of cell it has absolutely nothing to do with the chemistry, i have both Lithium ion and LiFe 18650 cells.

So you need to check what chemistry yours are.

To confuse matters even more Panasonic (makers of most Lithium-ion 18650 cells) use cells with slightly different make up.
Some will be NNP others PSS, to be safe i stick to 0.5C charge rate.

More details here:
http://industrial.panasonic.com/www-...ACA4000PE1.pdf

I charge using my RC charger at 0.5C using the LiPo mode.

To clarify this is ONLY for the lithium-ion 18650 cells, LiFe will need to be charged differently.

For my LiFe 18650 cells i use the chargers LiFe mode and again charge at 0.5C
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Old Jan 31, 2013, 08:21 AM
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Charge in LiIon mode.
You get double the lifespan then.
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Old Jan 31, 2013, 05:09 PM
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or just ask the previous owner how he charged them! obviously he has been doing what they like. I would prefer to balance charge.... but i have read about alllot of ppl that have great results not balance charging But !!! don't fast charge! like julez says... a charge rate of .5c would be prudent without the balance plug.
Or....... you could add the balance plug. Just run one more wire to the opposite end of the batts that your taking power from and that will be your middle wire, the other 2 are red and black on the power end that your tx connector is attached to. Just check your voltages before you plug it into your charger! from black to first wire will be cell 1, from middle wire to other end red will be cell 2. Both these should be half pack voltage, and if you check opposite ends "red to black" should be full pack voltage. But if you don't know what chemistry they are for sure .. well..... in the end it's up to you. What your comfortable doing and how much you want to learn.
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Old Jan 31, 2013, 06:13 PM
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Originally Posted by cbr6fs View Post
A lot of confusion here.
18650 donates the type of cell it has absolutely nothing to do with the chemistry, i have both Lithium ion and LiFe 18650 cells.
Yes, but the common sort are 4.2V. Especially those sold as Lithium Ion.
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Old Jan 31, 2013, 06:24 PM
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Originally Posted by FyreSG View Post
The 2 batteries are soldered in series. Is it possible to charge one battery at a time, while they being soldered in series? Perhaps connecting the positive and negative terminals of one battery to charge, then when that's done, charge the next battery the same way? Sorry if this is a dumb idea.
That is anything but a bad idea, especially of you do not possess a balancing charger.

Charging single cells via the balance tap is my preferred method for any LiXX series connected pack that is wildly out-of-balance as doing so is significantly faster than bleed balancing the high cells.

Obvious caveat here is to ensure that both cells are at the same charge state prior to attempting to discharge as forgetting to charge one of the cells may result in a destroyed cell during discharge.

Mark
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Old Jan 31, 2013, 09:39 PM
Canadian Bacon
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The 18650 designates the size of the batt. It's 18 mm dia and 650 mm long. Earlier li-ion batts were rated at 3.6. volts. Now they're rated at 3.7. On the Eco 6-10 charger which has both 3.6 for li-ion charging and, of course 3.7 for lipos, I prefer to charge them at the 3.6 volt rate, just to make it easier on them. I've given new life to a lot of power tools with worn out nicads and nimh by installing the li-ions.

Gord.
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