I have been charging my batteries at 1 amp. They are all 14.8V and range from 5200 to 6600 mAh Li-ion. I’m using a Tenergy TB6B charger. Is 1 amp to low?
Louis,
1 Amp is lower than recommended. Most Li-Ion OEM cell manufactures suggest a range of 0.5-1.0C charge rates unequivocally realized of the actual cell/battery in play.
In your circumstance a 5200 and 6600mAh battery; I’d suggest 0.8C its a low and slow value, universally accepted in the industry and negates unnecessary/unwanted heat potential which will help one realize a reasonable battery life cycle.
5200/0.8 = 5200mAh/1000 = 5.2A, 5.2Ax0.8C = 4.16A; minimum charge value = 2.6A
6600/0.8 = 6600mAh/1000 = 6.6A, 6.6Ax0.8C = 5.28A; minimum charge value = 3.3A
Your charger is rated for up to 5A, that will suffice for 6.6Ah battery.
Michael
Louis,
No, always charge your lithium battery-packs at 1 amp.
thanks,
???
( C = battery capacity in amp hours, in this case 5.2 and 6.6 AMPS)
I have problems with both recommendations. A tiny one with Michael’s definition of “low and slow”, a big one from Ricks suggesting a rate 1/5 to 1/6 of what is possible.
Low and slow would be more like the old trickle charge on nicads. Low and slow would be under 0.5 C, not 80%.
A “normal” fast charge is about 1 C. Years ago that was about the fastest charge that batteries could take, although now there are batteries that will take over this, but my opinion is that their life is shorter because of that. Nevertheless people want shorter charge times.
But charging a 5.2 amp hour battery and 6.6 amp hour battery at 1 amp? Wow, I could grow a beard waiting.
Clearly with lithiums you need a good charger that properly terminates charge, but if you don’t have a good charger, my opinion is that you should not possess lithium batteries at all.
Greg
OEM cells that I am familiar with in the 18650 Li-Ion cell/capacity (2200-2700mA) configuration, such as Samsung, Sanyo, LG and Panasonic all very to some degree with regard to their specific stated charge current specification.
In the case of using these cells in Parallel battery configurations, the batteries capacity is factored to glean charge current/amperage. For example a 2S2P 5200mAh 14.4V battery is comprised of eight 18650 cells, or two four cell batteries wired together in parallel. In this circumstance, the charge current required to charge two cells in parallel doubles. If you have two cells each requiring 1.3A @ 0.5C or 2.6A for the eight cell battery.
FWIW: the aforementioned cells are utilized by battery packagers/resellers to assemble their battery pack offerings. To that end; there are other less known/recognized OEM 18650 cell manufacturers.
A Lithium-Ion batteries charge current value (amperage) is calculated by multiplying the batteries known capacity by the charge current/amperage or ?C value.
C = battery capacity, typically expressed in mAh.
1C expressed as a charge current/amperage rating/value = battery capacity or C muliplied by a factor of one.
0.5C expressed as a charge current/amperage rating/value = battery capacity or C multiplied by 0.5.
To calculate charge current; divide battery mAh capacity or C by 1000, then multiply the result by the charge current factor.
5200/1000 = 5.2Ah
C=5200mAh
C=5.2Ah
5.2C x 0.2 = 1000mA or 1.0A charge current
5.2C x 0.5 = 2600mA or 2.6A charge current
5.2C x 0.8 = 4160mA or 4.16A
5.2C x 1.0 = 5200mA or 5.2A
OEM published charge values:
The averaged summary below was garnered from OEM manufacturer datasheets. Some of the sheets simply suggest a mA value.
Samsung: Std. charge: 0.5C and or C/2
Rapid charge: 1C
Sanyo: Std. charge = .73C
LG: Std. charge = 0.5C and or C/2
Rapid charge = 1.5C
Panasonic: Std. charge = .65C
Since it’s not obvious to consumers what OEM branded cell his battery pack is comprised thereof, some assumptions can be made based on the data noted above.
Furthermore it appears to be universally accepted of today’s 18650 Lithium cells that a 1C charge algorithm is viable for everyday charging. With that in mind my “low and slow” comment was offered out of context. I was suggesting @ 0.8C its lower and slower than atypical 1C ratings were seeing recommended today.
Michael
And I completely agree with your much expanded and very clear post.
Now Rick, please tell us why you recommend a 1 amp charge on 5.2 and 6.6 amp hour batteries.
In the good old days of nicads, and even nickel metal hydrides, “smart” chargers were not the standard. Nowadays, you cannot charge a lithium battery without a smart charger, unless you want a fire and or an explosion.
Thus, all the chargers you sell for lithiums must be smart chargers with charge profiles tailored for lithiums, furthermore, since you are a battery supplier, I would guess you have even more sophisticated ones that have cell monitoring/balancing, and also a separate temperature probe as backup.
Therefore, I cannot understand why you recommend such a low charging current. You can still overcharge a lithium battery with a 1 amp constant charge current.
Regards, Greg
Perhaps low charging rates prevent failure / guarantee expenses…
Its appears to be universally acknowledged by OEM cell manufacturers that the STANARD Li-Ion charge interval is approximately 3hrs, depending on the SOS (state of charge)…
I’m not aware of any OEM cell manufactures that have published charge rates below 0.5C.
Diminishing returns can be expected of long/slow low current charge intervals with CC-CV algorithms. In fact its my belief that its a recipe for overcharge. In laymen’s terms the reasoning is rather simplistic; whereas lab tests have revealed charging at less than 0.5C takes many hours longer than the OEM recommendations of 3.0hrs and can result in the battery already being fully charged @ 4.1V. Negating the need for the constant-voltage phase to 4.2V and or the detrimental voltage/heat stress associated with same.
Soft overcharge encourages the production of metallic lithium particles and the associated safety compromises thereof, dendrites and or cell oxidation at the least.
Michael
I think perhaps that there is thinking that charging at a much lower rate makes it safer. I believe that most of the horror tales about lithium batteries are:
-
damaged batteries, dents, pierced
-
operator error, overcharging, wrong voltage, current, resetting charge cycle, etc.
-
charger failure
You can still overcharge a battery at 1 amp, and I don’t believe it is any safer than charging at 0.5 C.
Greg
I have the Tenergy TB6AC. Its smarter than I am. I set the battery type, voltage and amperage, plug in the battery, hit the “Do It” button, and a few hours later, the charger tweedles at me that the battery is “cooked.”
There is even a button on the side that, when pushed, will butter the toast when it pops out.
I don’t think that I could set the amperage of the charge. The directions are written in Chinglish, that special language created by native Chinese speakers who have one semester of English under their belts.
Steve,
The Tenergy TB6AC allows the user to set the charge current, it utilizes a common chip, seen in many chargers and works quite well IMO.
Greg,
I think #2 holds the most water. User interaction. i.e., inappropriate settings and or the wrong type of charger were for some time a BIG problem. Educating users on the need for the correct charger specifically for the battery chemistry in play was a huge for several years.
I’ve mentioned this in the past, the MAXIMUM charge time interval allowed for safe charging of any battery chemistry is paramount. Nowadays most of the truly smart chargers have a feature which times out when the charge interval has elapsed and shuts down the charger alerting you of same (Tenergies TB6AC has this feature). I used to suggest and the idea still has merit that users employ a power line timer device, understand your needs and set the device to shut-off when the maximum calculated charge time has passed. These are simple inexpensive devices available almost anywhere.
If your batteries do NOT reach and or complete the appropriate charge cycle something is likely amiss. Continued charging is not going to solve the problem, one or more of the cells more likely than not is damaged. Battery packs with cells in parallel are more likely to be a problem than cells in series only.
Michael
(http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-laughing.gif)So, how does one set the charging amperage on the TB6AC?
So, lemme see if I get this right. A 5200 MaH battery being charged at 1c would be charged at 5.2 amps?
Beats the hell out of me, Terry. I just let Otto handle it for me. (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)
Terry Burr said:
So, lemme see if I get this right. A 5200 MaH battery being charged at 1c would be charged at 5.2 amps?
Yes, although I would recommend less than 1C, 0.5C-0.8C charge rates will fall between the OEM recommendations. 1C would be a rapid or fast charge regimen if need be. If one has the time there is no reason to fast charge.
Michael
Steve said:
So, how does one set the charging amperage on the TB6AC?
Steve,
Take a look at the link below, lots of video tutorials.
https://www.google.com/?gws_rd=ssl#q=tenergy+tb6ac&tbm=vid
Michael
So, you don’t know, then, eh Michael?
Steve said:
So, you don’t know, then, eh Michael?
Know, what how to set the charging amperage on the TB6AC? Yes, I do as I have a couple chargers with the same chip.
The video links provide all the info needed in a visual format. I watched several of them, there great IMO.
Michael
So, instead of giveing me a simple to use, two or three sentence answer, you send me to a page that has ten or so videos, of uncertain origin, that I’m supposed to sort through, in hopes that I might get the kernal of truth that I’m searching for.
Thanks, pal, you’re a big help.
Truth be told, its not a three sentence answer. There are other considerations that must be addressed in addition to “setting the charge amperage”.
The links provide this info much better than I could describe IMO.
Michael