Voltage to charge pack at?

jawnn

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I have a an 18650 pack using two sets of two in series for 7.4 to 8.4 volts..... a cheap charger came with it that puts out 8.5 volts at 1.8 amps. Is this safe? should I be using a lower voltage? years ago some one had a fire from this pack, was it because of the high voltage?

I am using the same charger (that changes from red to green when done) for a pack that is rated at 12 volts. They said charge it under 2 amps.
 

jawnn

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Is there no one on this forum? or is every one just ignoring me for some reason?

I was testing out this ac to dc charger and got the red lite to come on for the smaller voltage pack. But the 12 volt pack will not go red. is that because there is not enough voltage to create a resistance?
 

jawnn

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well I found one that looks better but it does not appear to have a dc connection, runs off ac only. any one know what pack chargers will run off dc?



Tenergy Smart Universal Charger for NiMH / NiCd Battery pack 7.2V - 12V with charging current Selection/Temperature Sensor
 

jawnn

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I found another one, but does it have a way to plug into dc sockets?




41jrYtQUZ2L.jpg






  • 3.6 Volt -14.4 Volt Lithium Ion Li-Ion Rechargeable Battery Pack Smart Charger
 

LEDPunisher

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Do not use a charge voltage over 10% your battery nominal voltage as a general rule of thumb. 7.2V would get ~8V maximum and 8.4V would get ~9.25V maximum. This is to prevent thermal runaway while charging. 8.5V is roughly in the middle, so it should be fine, though I'd prefer that to have ~750mA for output current versus 1.8A for thermal considerations.
 

jawnn

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sounds like i should definably get a smart charger. but I NEED ONE THAT WILL PLUG INTO A DC OUTLET. please give me a name ??



Do not use a charge voltage over 10% your battery nominal voltage as a general rule of thumb. 7.2V would get ~8V maximum and 8.4V would get ~9.25V maximum. This is to prevent thermal runaway while charging. 8.5V is roughly in the middle, so it should be fine, though I'd prefer that to have ~750mA for output current versus 1.8A for thermal considerations.
 

LEDPunisher

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DC outlet, like 12V car outlet? Assuming 12V, you could put a ~3.2V LED and a ~20 ohm resistor in series on the 12V positive rail, hook up your power connector after that, and just use DC charging at 8.8V and ~600mA. Bear in mind there's no cutoff with this very simple but working design, you need to watch your charging time.

I can't give names as I know none, sorry! :)
 
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SilverFox

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Hello Jawnn,

Those types of chargers are used mostly by the people that use radio controlled vehicles. You may want to browse through some of the RC forums to see if anyone has done a comparison of that charger with other models.

Tom
 

Aquanaut

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sounds like i should definably get a smart charger. but I NEED ONE THAT WILL PLUG INTO A DC OUTLET. please give me a name ??

I use an "Imax B6 Ultimate" smart charger with a DC power source. This charger will work on 11V to 18V DC. It will balance charge up to six 18650s in series at one time, however for balance charging, you will need access to the individual batteries. Besides lithium, it will also charge/discharge/cycle NiCd and NiMH, and charge/discharge lead acid batteries.

There are various versions of the Imax chargers. Just Google "imax b6 charger" for more choices.
 

jawnn

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I found this one on amazon, is it any good? Tenergy TB6B Multifunctional Balance Charger

or this one:
[h=1]Tenergy TB6AC 50W/5A AC/DC Dual Power Balancing Charger for NiMH/NiCD/Li-PO/Li-Fe/SLA[/h]
It looks like I need to buy extra plugs like

Etekcity® BAOFENG Car Charger Cable

that my not be regulated to 12 volts when charging my big battery at 14.6 volts, but maybe if the charger doesn't draw 14 volts it will not matter??


I tryed charging my 18650 12 volt pack at less than 12 volts.....it sucked power out of the pack
 
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jawnn

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found one that Is even cheaper. but does it have heat sensors? what is wrong with it?



iMAX B6 OEM Battery Balance Charger For 1-6 cell Lipo, Li-ion, LiFe (A123), Pb, 1-15 cells NiCd and NiMH Batteries
 

Aquanaut

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found one that Is even cheaper. but does it have heat sensors? what is wrong with it?

iMAX B6 OEM Battery Balance Charger For 1-6 cell Lipo, Li-ion, LiFe (A123), Pb, 1-15 cells NiCd and NiMH Batteries

Simple answer: yes, it does have a heat sensor. It is relatively difficult to tell you what is wrong with it compared to more expensive versions.

You can answer all of your own questions by looking at the manual:

http://www.skyrc.com/index.php?route=product/product/download&download_id=17
 

jawnn

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the right kind of pack??

forgot to look at the manual, bought one for about $22.....

the manual says I should not plug a pack into it that has a protection circuit as integral part of the pack. Does that mean I cannot charge this pack: Tenergy 31012 Li-ion Rechargable Battery
http://www.batteryjunction.com/tenergy-11-1v-2200.html

WHAT ARE THE RIGHT KIND OF BATTERY PACKS?? DO THEY HAVE A DISCHARGE PROTECTION CIRCUIT?? I need protection when running my lights.

This looks like the right kind of battery pack, but will it work with my bicycle lights?

Neewer® 11.1V 2700mAh 25C 3cell Li-po Powerful Battery Pack and Cable XT60 Plug for DJI Phantom

Is there any packs made from 18650 batterys for this charger?

Is there a way to fix the pack that I have? don't look like it to me.
 
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SilverFox

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Re: the right kind of pack??

Hello Jawnn,

I think you may be getting "the cart ahead of the horse" in your thinking.

A quality charger will charge any battery pack within reason as long as the voltages match up. There is no right kind of battery pack.

The process goes like this.

You have an application that runs on batteries. You decide to use rechargeable batteries. You get a quality charger to charge the batteries for your specific application as well as looking forward to other applications that you may have an interest in. You follow safe charging practices and enjoy your application.

It appears that the charger you have doesn't work well if there is a protection circuit installed in the battery pack. Your choices when using that charger are to remove the protection circuit and build in protection into the light. Or you can simply use an unprotected battery pack. Another thought is to devise a way to bypass the protection circuit while charging.

I would suggest you pick a battery pack that will work well with your application, then worry about a charger. It appears that your charger incorporates balancing while charging. This means that each cell is monitored and adjusted as needed. The protection circuit does not attach to each cell and would present a problem with balancing charging. If you charger can charge without balancing (bypassing this safer way of charging) it will charge your battery pack without alteration.

Tom
 

StandardBattery

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Re: the right kind of pack??

I think post 2, and the last line in post 13 indicate you are in over your head. Sit back, relax, if you can't find someone locally to get you started with your application, sit down and do some reading. Maybe stop into a hobby shop that carries chargers and pacs and have a look around and talk to the them. You could try to google your exact pac and see if you cajn find what others are using to charge it, and why.
 

jawnn

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Re: the right kind of pack??

well I was studying the manual, and it says that if I use a battery like I have the charger will be damaged.

so to save some money, i want to find the right kind of multi pin plugs and re wire the packs that I have. is there some easy to apply foil tape so I DO NOT HAVE TO SOLDER DIRECTLY TO THE BATTERYS?

No idea where to get the pin plugs. no hobby shop here.
 
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