Charging time for Ultrafire 18650 6800 mAh battery

I would like to find out how long to charge the above battery.

Charger puts out 500 mAh.

Thanks.

Reply to
Andy
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ball park guess 6800mAh/500mA = ~14 hours

Reply to
Lasse Langwadt Christensen

Unless this is a D cell or some highly specialized battery chemistry, there are no 6800 mAh AA cells. Any rechargable with "fire" in the name is a lie. They are well documented on the web.

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Rick C
Reply to
rickman

You missed the 18650 in the subject title, But you are right anyway. There are no 6800 mah 18659 batteries. I think the best 18650 batteries are just over 2000 mah.

Dan

Reply to
dcaster

I'd guess about 3 hours to full charge. Not to be confused with the ADVERTISED 6800 mAh.

My 4000 mAh Ultrafire cells perform far WORSE than cells removed from DEAD laptop batteries.

Charging lithium cells safely is not a simple process. Assuming your charger is designed to charge those cells, it will do whatever it does. Rarely do the numbers on the package give you much useful information.

As a cautionary note... I bought mine for a quarter at a garage sale, so I don't know where they came from. The included charger connects two cells directly in parallel. If you put in one dead one and a fully charged one, you may make some serious smoke/fire.

Reply to
mike

Not enough information to answer. There's more to charging a LiIon battery than cramming 500 mA (not mA-Hrs) into the battery. The charger has to know the SoC (state of charge) so that it doesn't overcharge your battery. It also has to make sure the charger NEVER goes over 4.2VDC and check if the battery is getting warm. Lots of things that can go wrong. Some good stuff on charging LiIon:

What you should do is purchase a suitable charger for an 18650 cell. For example: or a dual charger:

Also, your Ultrafire battery is certainly not going to deliver 6500 mA-hrs. My test of an Ultrafire 3000 18650 cell shows that it will deliver about 800 ma-hr with a 1.3A constant current discharge, which is what one of my flashlights like to draw.

Reply to
Jeff Liebermann

There are some that are as good as 3500mAh +/-, but 'Ultrafire' is known *not* to be a source of such product.

Your estimate of 1800-2000 is probably reasonably good. I've been meaning to set up the logger and electronic load but it probably won't happen soon.

--sp

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Spehro Pefhany
Reply to
Spehro Pefhany

Most batteries are specified to be (safely) charged at C/20, some at C/10.

Reply to
Robert Baer

Wrong. The *DISCHARGE* rate is C/20 for the sole purpose of providing a uniform test of battery capacity in ma-hr. If one charged a 3000 ma-hr cell at that rate, it would take over 20 hrs for this battery to be fully charged. Obviously, that's not happening.

Maximum charge and discharge current rating vary by battery chemistry and construction. As an example, a 2 cell 1000 ma-hr battery pack: is rated at: 30C (30 amps) constant discharge 40C (40 amps) intermittent discharge 2C (2 amps) maximum charge rate.

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Jeff Liebermann     jeffl@cruzio.com 
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Reply to
Jeff Liebermann

C/20 is a safe constant charge current for NiMH batteries if you don't have a fast charger, C/10 for NiCd, neither applies to Lead-Acid or lithium.

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Reply to
Jasen Betts

Read what he wrote. A C/20 *charge* is safe. A C or 2C or even 10C charge might be possible but you have to be really careful.

Reply to
krw

Panasonic make them. They just recently improved from 3400mAh, as tested by a night-hiking mate of mine.

Unless you get repackaged spent cells, which *fire is known for. Then you're lucky to get 800mAh.

Clifford Heath.

Reply to
Clifford Heath

Please note that the title of this thread is "Charging time for Ultrafire 18650 6800 mAh battery". To the best of my limited knowledge, neither NiMH, NiCd, lead-acid, or carbon zinc batteries are available in an 18650 form factor or are sold under the name of "Ultrafire". However, you're wrong again about NiMH "safe" charge rate. The NiMH chargers that I own (Maha, iMax B6, Sanyo Eneloop, etc all use a negative dV/dT slope to detect EoC (end-o-charge). The charge rate varies, but the average is somewhere between 0.5C and

1.0C.

Charging NiMH cells at C/20 is considered a "slow charge" and is a great way to kill a NiMH battery because of the lack of a negative dV/dT slope to signal EoC: "It is difficult, if not impossible, to slow charge a NiMH battery. At a C rate of 0.1C to 0.3C, the voltage and temperature profiles do not exhibit defined characteristics to trigger full-charge detection, and the charger must depend on a timer. Harmful overcharge can occur when charging partially or fully charged batteries, even if the battery remains cold."

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

how many hours to charge a 18650?please be inform me

Reply to
carlonunez34

snipped-for-privacy@gmail.com wrote in news:89fccd51-9ff3-425b-acdb- snipped-for-privacy@googlegroups.com:

There is no such thing as an 18650 that can do 6800mAh.

But as far as a standard 18650, which is about all that can be packed into one, is on google.

Google is you friend. I found charging tables on this page:

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Reply to
DecadentLinuxUserNumeroUno

1
Reply to
Rheilly Phoull

snipped-for-privacy@gmail.com wrote in news:89fccd51-9ff3-425b-acdb- snipped-for-privacy@googlegroups.com:

Look at the specs on this data sheet for a product.

There is a nice data sheet for that battery.

Yours will be similar.

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Reply to
DecadentLinuxUserNumeroUno

How do you know your battery is 6800mAh? Did Amazon or, even better yet, Alibaba tell you it was 6800mAh? (This should be good).

Reply to
krw

If it's 1Ah (1000mAh) then 1A for 1 hr, or 1/2A 2 hrs etc. If it's 2Ah, double that etc

NT

Reply to
tabbypurr

Or ages and ages with a USB driven charger...

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Reply to
TTman

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