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Friday, August 12. 2011
The last time I escalated King Mountain for my mini VHF expedition, I brought along a 12 Volt, 7 Ah, sealed lead-acid battery to power up my FT-817ND radio. That battery weighs a hefty 6 pounds (2.7Kg). Luckily, we only had less than 30 minutes of hiking to reach the top of the mountain. Besides, I use that battery in my home alarm system, so I had to find a better mountain-top power solution for my next portable radio expedition.
While reading the FT-817 Yahoo! group, I learned about this 12V,6800 mAh Rechargeable Li-ion Battery sold on eBay for $19 (U.S.), including charger and shipping. I elected to order one from eBay seller "sinedya" directly from China. This is a super-power seller, with more than 208,000 feedback entries!
The exact battery model number is DC-12680 and it is very similar to the the one shown on this picture. This thing is a feather (at half-a-pound (250g)) compared to the big fat battery I had used before. It even has a power switch on it (not visible on the picture). It is hard to believe that this battery would provide essentially the same battery capacity as the lead-acid one. So I had to test it!...
...And here are the test results. Will you be surprised to read that the battery far from meets the 6800mAh spec? Analyzing this figure reveals the facts. With a constant discharge current of 1000 mA, the battery voltage falls from 11.5 V to 8.75 V in 150 minutes. This corresponds to a capacity of 2500 mAh, far from the specified 6800 mAh. I cut off the load at 8.5V, but even if we extrapolated the curve down to zero Volts, we will still be far from the specified capacity. I re-tried the same test with a load cutoff at 8 V and the resulting curve was almost identical to the first try. And trying with a lower load current of 500 mA (not shown) did not improve the performance. Disappointing...
The other fallback of this lower than expected battery capacity is the larger voltage drop as a function of load current. This is because Li-ion batteries have a higher internal resistance than NiCd and NiMH type batteries. And the lower capacity, the bigger the drop. For a 1 Ampere load current, the drop is about 1 Volt at the beginning of the discharge curve. Not insignificant if you want to use high power on your rig. Note that the FT-817 draws around two Amperes when transmitting at 5W; that is double the test current used here...
I had had another case of under-performing battery in the past. It is no secret that the no-name batteries (usually made in China) are not as good as brand name batteries. So in a way, I am not surprised of these results. I would not be surprised either to find out that most batteries, regardless of the manufacturer, do not meet their advertised rating. But we are talking here of about 37% of the advertised number... Come on!
So my next step was to contact the seller to see what they could do to correct the situation. I provided a detailed explanation of the problem along with the discharge curve to the seller. They replied (very respectfully I must admit) that they had contacted the manufacturer and that it was a labeling error (yeah right...). We then agreed that they would refund me 50% of the cost. And they did promptly.
-Expect the battery capacity to be much less than the advertised specifications. I got 36% of the quoted 6800 mAh.
- Use these batteries in applications where the peak current is much less than the battery capacity. In other words, forget about transmitting with 5W Rf output. But 2W RF from the 817 is a reasonable expectation.
- Knowing the above, 19$ including charger and delivery is still a fair price for a 2500 mAh 12V battery, but it is not a bargain nor a marvel. Hopefully, the battery will have a reasonable life span... and that could be another disappointment down the road...
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Usually the capacity of a battery is measured considering the current that batery can provide for 20h of continuous usage.
See for example:
In this particular situation, have you tried to discharge it at 340mA (6400/20) to see if it will work for 20h (or close to this value)?
My experience (but with NiMH batteries) is that even the best ones (ex. the Eneloops) cannot provide the full capacity from the specifications for currents higher than 1/20.
If you get a measured capacity of 2500mAh with 1A discharge current, then for sure is much better than any NiMH cells rated at 2700-3000mAh.
73 Dan YO3GGX
Thanks for your suggestion. It is pretty easy for me to try that, and I will. I will report the results back on this blog. But I doubt that there will be a significant improvement on the results.
I haven't yet taken the time to read all comments, and perhaps I should.
The battery is cheap enough to risk getting one and see what happens.
In my case I should be using it to power a Blackmagic Pocket camera, which uses internal batteries that presently last less than 30 minutes, so I already prefer an external 12v 4.5Ah nimh battery I had around for my laptop.
I already bought some other eBay batteries, but I haven't yet tried them or trust them as much as this nimh. But LiIon is a better terchnology, so I'm willing to give this one a try.
One thing several users commented is about the real capacity of this battery. One battery, black plastic packed, also failed on me and refuses to charge, probably due to a faulty element inside. If the elements used are 2100mAh types, then you do have to parallel/series them to get to the voltage& capacity they claimed, and charging might be compromised.
Are there any other, perhaps reliable brand types, that can REALLY provide what this battery claims: 12V @ 6.8Ah?
Using it I can forget about the battery question when I'm shooting.
I think that what is going on with these suppliers of rechargeable batteries is that the batteries are not new. The batteries are probably swap overs from some equipment half way through their lifespan. It is not unusual for large scale military operations to unload surplus gear into the public market. The military may have used millions of these batteries as power backups for installations deep underground etc...so as to keep the equipment in prime operating conditions, and to recover some expenses, the military would change the batteries for new and sell the used to resellers. The batteries can easily pass for new ones. Thanks for the detailed analysis of the product
You got lucky, I bought 60 18650 cells(blue ones) rated at 5000mah to build a power pack for a electric bike. On paper it was a 1.2 kw pack(40V) that would have given me a range of around 45kilometers, I got less than 10%. Does any one actually make 18650 cells that gets over 5Ah IRL? Later I got 3 18650 cells rated at 6800mah to use in led flashlight I got about 300 mah (red ultra fire cells) Do all Chinese battery factories lie as a rule?
The first pack cost me with a special charger around $200 + my labor in building them, they work, but not for very long.
I have an Element 24" 12V TV that draws 36 Watts. Bought one of these black case MAH 6800 Batteries. According to our calculations With this limited draw as compared to a laptop that uses a 4400 MAH (2hours) This battery should give me 4 hours or more. I shuts down between 45minutes and 55Minutes. I need at least 2 hours run time as I use this TV as a idiot box during shows.
Any suggestions. Originally it was suggested to use a LIPO battery
but I was concerned with voltage drop damaging the battery.
Having disassembled one of the 9800 mHA batteries I can add that the internal wiring to and from the batteries and switch is a small gauge wire.
It appears to be about 30 gauge wire wrap type wire.
This would contribute to the measured smaller capacity as the losses in the wiring would need to be added to the measured capacity.
This could be over come by measuring its capacity at a smaller current.
Also I could not see any protection devices as are contained in most Li batteries unless they are embedded in the actual batteries. I assume that the small wire is intended to act as a fuse.
Interesting discoveries you made! I will likely test with an even smaller current, but I had done it with a 500mA load and results were similar in terms of capacity.
The eBay listing claims that there is an over-discharge circuitry. I is possible that this could be a built-in feature in each cell. But again, the contrary would not surprise me!
In response to the above suggestion from Dan to evaluate the battery pack with a discharge current of C/20 or 320mA, I have performed a full discharge cycle at the suggested load current. I got 2800 mAH. It was expected that the measured capacity would be slightly higher because the battery voltage starts at a higher level (the load current is less, so the voltage drop across its internal resistance is less).
So in conclusion, no change conclusion and opinion!
Thank you for taking the time to run the test and publish the results. I was also considering running tests to replace 12 volt gel-cell batteries (sealed lead-acid) with these li-ion batteries. The size and weight advantage is very tempting. We needed 2 amps for 2 hours and I thought that the additional 50+% capacity would provide the cushion for the high current draw and for sufficient life. Obviously not.
Your tests indicate that the claimed capacity of these batteries is just plain fiction. Too bad.
A few remarks on previous comments.
1. Wire size: While a #30 wire is on the small side, it would not effect the test results. The resistance of #30 wire is about 0.1 ohm/ft. Even if there was a foot of wire inside the battery it would have created only 0.1 volt drop at 1 amp. Compensating for this drop shifts the graph by an imperceptible amount.
2. Discharge rate: There is no set value for running battery tests. Because of the nature of lead-acid batteries, not all of the porous plate surfaces and lead-oxide paste are exposed equally to the acid. A slower discharge rate will allow all of the battery to chemically react. For car batteries the 20 hr rate is used to simulate leaving the lights on. Cranking power is the capacity of at high loads, such as 50 or 100 amps and will be much less than the 20 hr rate. But let the battery recover and it can provide additional power.
Deep discharge batteries for electric carts, trolling motors, etc are measured at the 10 hr and even 6 hr rate. The effectiveness of the chemical reaction in Li-ion batteries is not very time dependent which is why they do not have any great recovery capacity. And why reducing the current draw in the test did not have much effect.But their relatively high internal resistance will reduce total energy output as current draw increases.
3. Protective circuit: Overcharging or too high a current draw will heat up these batteries which can result in shorted cells and thermal runaways. The heat can melt the case and result in fires. Which is why these batteries, at least from known manufacturers, have thermal cutout circuits. And why they are not welcome on airplanes.
It would be interesting to run the same tests with branded batteries such as the Sony E80S (14.4v 6800 mAh)
Thanks all from saving me repeating the tests . The pack sounds like a 18650 3000 mAH pack, see http://www.lygte-info.dk/info/Battery%2018650%20UK.html for tests and http://www.lygte-info.dk/info/battery%20protection%20UK.html to see a protected Li-Ion cell. Just measure the pack- if 4x18 mm wide this is likely the cell tyoe used. The length as noted in link will be longer for the protection IC - maybe 69mm. The Ultafire 3000 mAH red-grey cells are about $8 a pair from eBay so the price you paid with charger is probably not too bad.
Cheers Peter (Got your link via KX3 forum, Yahoo.)
This battery pack measures 97mm x 62mm x 19 mm.
I've got the same battery but just a little mark for the maker of this article; The battery consists of 3 cells. 3*4.2 volt when they're charged 3*3.6 volt when they are discharged .. you should not drop the total voltage of the battery below 10.8 volts. If you say you discharged the battery 'till 8.75 volts you permenantly dammaged the cells inside the battery, they won't be able to deliver a full charge anymore. If you ran the test from 12.6 volts till 10.6 v the result would have been much better and your batteries will last longer.
Thanks for providing a comment. There is something not quite right with your description of the battery pack and/or how far we can discharge it. If indeed, we should stop discharging at 10.6V, then according to the discharge curve this battery is useless because it has almost no capacity!
Please provide a reply to my statement if you will. Thanks.
I did some more research and found some documentation from sony about discharging Li-Ion batteries on http://www.sony.com.cn/products/ed/battery/download.pdf page 17:
As charge/discharge cycles are repeated, the battery capacity (ability to hold a charge)
gradually declines. However, when batteries are charged and discharged under the conditions
recommended by Sony, they can be used for 500 or more charge/discharge cycles.
The maximum voltage for charging is 4.2 V, and the cutoff voltage in discharge is
2.5 V (for hard carbon batteries) and 3.0 V (for graphite batteries with cobalt oxide
cathode). If batteries are charged or discharged at voltages outside these ranges,
ba t tery per formance and s a fety a re compromi sed. Li thium ion recha rgeable
batteries are not subject to the so-called memory effect seen in alkaline aqueoussolution rechargeable batteries, in which the discharge voltage is reduced when
repeated shallow charge/discharge cycles are followed by a deep discharge.
If you take a look at the discription from sinedya they give an output voltage from 12.6 to 10.8 Volts as working voltage. http://www.ebay.com.au/itm/12V-Rechargeable-Li-po-Battery-CCTV-Cam-6800mAh-2-/250971461871?pt=US_Batteries&hash=item3a6f1098ef#ht_3411wt_1163
Most manufacturers advice not to go below 3.5 Volts per cell for the longest battery life, with an absolute minimum of 3 volts. When you drop below 3 volts (for batteries with cobalt oxide cathodes, I think they are, correct me if I'm wrong) the capacity of the battery degrades very fast and permanent battery is not very unlikely. Sinedya claims to have an undercharge safeguard, but there is no, at least ... no decent one. In your second run you can already see your battery capacity decreasing a little bit.
I correct my first note about maximum discharging it to 10.6V to an absolute minimum of 9 V.
9.0V sounds much more reasonable for a minimum useable voltage. This battery has a significant series resistance, which does not help in higher current applications.
Having to manually cut off the load at a certain voltage is not something we are used to. Over the years, we have developed the reflex of fully depleting Ni-Cd and Ni-Mh batteries... It is true that the battery is advertised as having a built-in over-discharge protection, but I wonder how much of a lie this is...
Bottom line is that you should select the battery based on the projected application, not solely based on its labeled capacity. You should also learn about the battery technology you use, something you did well.
I suggest you guys look at motorcycle batteries. Like C4, C5, C6. Small and expensive but a lot of power. You can start your car with these hand held batteries. KJ6WVM
hi i am just wondering if anyone has had any problems with these 9800 mah li-ion batterys as i had bought one from ebay and 1 - 2 months after the cable coming out of the battery pack with the plug will play up (i.e) battery is fully charged and connected to a 12v device (like 12v powered speakers) but soon as you wiggle the output cable or slightly move the battery pack the voltage drops. as it has happened to me a few times and it it possible to solder in new connections like a plug and socket?
I had the same results as you exactly. Same battery. There is an internal circuit breaker in the pack. I shorted one while testing the voltage and they turned off. I flipped the switch and was back in business instantly.
I was going to purchase 500 of these for a project I wasted 100.00 plus shipping. My sellers name is enjoy deal.
Thanks for your blog on the issue. I wish I had found it 100.00 ago.
In the question as to discharge the battery at lower amp levels. I have done this. I have digital clocks which draw 0.78 amps at 12V to 0.49A at 10.6V
and another which is 1/2 that amount. The runtime is 3 and 6 hours respectively. I shut them down at 10.3 V because the 12V led system was barely visible. So your calculation is perfect. You could have taken them higher for the initial charge. My charger shut off at 12.7V.
By the way oour cell phones discharge at a much higher rate. almost.4c for a regular feature phone. I bet an iphone is much higher.
Thanks for taking the time to report back on your experiments on this battery pack. It is good to know that I am not alone! Despite its limited capacity, I use it to power up my JYE portable oscilloscope, my MFJ-249 Antenna Analyzer and I even use it for portable operation with the FT-817 QRP Transceiver. So far, it has been reliable.
First of all, i want to admit that I'm the battery supplier, produce the same kind of battery you are talking about using 18650 li-ion battery. We are relatively new to this niche market making batteries with switch and led indicator, but we have researched their battery too. I can provide some reality here about what is going on with Chinese li-ion battery.
In retailing market, the price is very low, most buyers are just comparing price and now know anything about technique, which pushes some suppliers turn to the low quality and fake capacity method, it could make them profit quickly, and i know they are not professional battery supplier.
We have researched their product:
1, B-grade battery cells
2, Use 3 single cell PCM rather than 1 pcs of 12V PCM
3, Welding is really bad
4, Charger without IC control
And what is a real cost of a quality 12v 6800mAh battery?
1. Battery cell
lithium polymer battery: $25
lithium ion battery: $14
2. 12V PCM: $2
3. Charger: $3
4. labor cost and accessories: $3
Above cost is depending on real costs of at least hundreds of pcs quantity, you can't expect a price when just making for like 50 pcs.
The lion batteries cam be drained lower than 10.6 V. Each pack no matter the maker has internal charge/discharge protection. As far as the 6800mah batteries they will shut down in case of a short circuit. Flip the switch and they are reset. Many others kill the BMS by short circuiting them. I have ordered some batteries from another maker and they are the best. I have to order them in small quantities because I am small potatoes. The ones I had made were 108 watt hour 12V batteries 12 cells. I have taken them down to 9.1 volts and they still perform as expected. My current draw is .72 amps @12 V and they run for 18 hours before my LEDs don't light enough to see.
Yes I agree the batteries are strange, With my charger its a 350ma with a green and red LED's , When DC 12680 battery loses charge upon connecting the charger a led turns green and other turns red after 10 min the green turns off but the battery is still not charged it usually takes over 24 hours for pack to complete charge cycle.
Too bad for me. Just read your great post and am thankful for it. I'm holding in my hands the same exact battery from the same exact seller. In my case though, the battery didn't even get charged with the supplied 12V 0.5A power supply. So I've cherged it with a 12V 1.0A supply and it the meter shows 11.1V output. Since all this is new to me, I'm wondering if changing the power supply for charging is dangerous, and what else should I do to avoid blow ups and such. Would really like to hear you educated input on this.
I only need 12V and 1A to power up some Arduino projects, so if anyone could recommend a reliable and safe solution I'd really appreciate it. Thanks.
I do not recommend substituting the charger for another one. You should only charge the battery with the supplied charger. You have to let the charger take the time required to recharge it. Li-Ion batteries are finicky when it comes to charging. There is a risk of damage and even fire if you over-charge. Li-Ion chargers are "intelligent" chargers in that they detect the state of charge and interrupt the cycle when the battery has had enough...
This battery is not a 12V battery. You will not get more than 12V for long. See the plots above. The voltage drops pretty rapidly. Still, it is a useful battery if you have a downstream voltage regulator for a lower voltage.
Hey, thanks for taking the time to answer. As for "supplied charger" and "intelligent"... The battery came with a 12V 0.5A unit that has a green LED, and after 12 hrs straight was not able to charge the battery. Or maybe I should switch the battery to its "I" state, thus making both the battery and the so called charger LEDs blink...?
My battery takes longer than 12 hours to recharge. It is more like 18-20 hours if I recall. It is a slow charge, but it is gentler on the batteries.
Leave the battery switch to off "0". My charger LEDs do not blink when charging. I go by memory here, but it is a continuously on green and red LEDs on the charger while charging. I believe the green will extinguish when the battery is ready.
Will do as advised and hope for the best
Thanks a lot - the seller seems to know so much less than you about the entire thing (...) and your help is really appreciated.
24 HRS later...
Not charging at all!
I'm trying with the switch set to "I".
Last time I managed to charge using a 12V 1A power supply...
Seems lie in my case The switch needs to be turned ON.
An hour in that state and the LED turns red. Battery shows 11.4 V
(Which I find strange... How many cells are in there...?)
At first I thought by charger was defective because the green light on the charger is strange. The green light does not turn on unless you plug in a battery that has been depleted to just under 11 V. Then the green light will remain on until the battery is close to fully charged. If you plug in a battery that is above 11 V, the green light will not turn on, however it is still charging the battery. So the green light is not an indication that the charger is charging the battery, and probably not a good indicator of when the battery is finished charging. Just ignore the green light and let the battery charge overnight to be sure you get a full charge.
I did a discharge test at 240 mA. My fully charged battery started at 11.85 V (yes, this is fully charged, I couldn't get a higher intial voltage on subsequent charges). The voltage drops at a linear rate until 10.8 V. Then it starts dropping fast. I stopped discharging at 10.5 V. There is not much capacity left at this point, and, as Jannick points out, discharging too much can damage the cells. Total discharge time: 7 hours. So the useful capacity of my battery is about 1700 mAh
Boy, 1700mAh is low... far, far from 6800mAh...
UPDATE: After 2 more cycles since my discharge test, the battery is now charging to 12.47 V after charging about 12 hours. Battery is getting better with age
My charger shows 12.6 volts. I would like to know what kind of li-ion 12 volt will charge with 12.6 volts. None of them i think. You need 14 volts to start with.
Um, no. These batteries are 3 cell (3S) lithium-ion batteries. They should be labeled 11.1V like all the 3S li-ion batteries sold for RC applications. Each cell has a peak voltage of 4.2 V per cell and an average voltage of 3.7 V per cell. So for a 3 cell battery:
3 x 4.2 V = 12.6 V peak
3 x 3.7 V = 11.1 V average
Look up "li-ion charging curve" on google images. The charger will output a maximum of 4.2 V per cell at the end of the charging cycle.
Can anyone recommend a better battery choice?I too have this piece of junk in my hands and just found this posting.
DC-12450 4500mAh pack from the same seller and the printed instructions state that the pack should be off and charger connected.
Next plug in the charger and see green light on charger.
Next turn pack to ON position and see charger light turn red to indicate charging.
When charger light returns to green while connected to the pack with the switch in the ON position then charging is complete.
Mine is new and just on first charge so I can not speak to how long it will take. The charger is labeled 1000mA
Matt, I simply went to Hobbyking and bought a decent safe and proven battery and charger. Indeed it costs a bit more but I feel much safer using it and it's worth the money
What model of battery and charger did you order at Hobby King? What is your experience so far?
I was hoping to get a little more advice on these. I recently bought one of these 3 cell pack, and I am using it to keep some items in a car running when the car shuts off. I basically need a rechargeable source that will charge with the cars 12-14 volt supply and supply 12 volts when the car is off. I thought this would be the perfect device but didnt fully understand the complication involved in trying to recharge these packs with the car battery supply. Any suggestions on a better source for this.
Thanks for this review, averted much frustration for me. Not gonna buy this on ebay.
I too thought I was getting a battery that would meet my needs. Advertised as 6,800 mAh. I also found the stated rating to be far from the use I was getting. I contacted the selling in China (eBay) and was given the run around and in the end eBay would not stand behind me. I opened the case up to find 3 VERY small Li-Ion cells with the following printing 8.36Wh @ 3.8V. The overall dimension of the combined cells were 2.25" x 2.25" x .5". The vast majority of the blue box was AIR. Doing the math this comes out to 11.4 volts and about 2,200 mAH....about 30% of the stated capacity. Do yourself a favor and do not purchase any of these as they are FAR from advertised.
Can anyone provide an alternative to the 9800mAh-DC-12V? I need to light a LED strip (about 16ft of it) for around 3 or 4 hours.
I too require a 12v li-ion battery pack to power an led strip for a minimum 6 hours (12v 25w total )
Does anyone have a recommendation.
I am confused as to why eBay continues to allow this product to be sold on their website .I also purchased a battery and it fell to perform as sold.
These batteries are still a GOOD VALUE for the price, even taking into account their capacity is about 1/3 of what is promised.
I paid about $25 for a 12V 6800mAh (actual capacity about 2200 mAh) battery with charger. The battery has a 'circuit breaker' on-off switch that protects from short circuits, and two cables coming from it--one is power-out, the other is charging-in (some rc batteries have only one connector for both power output and charging).
So far my battery is working great to power my motorcycle's LED brake light and signals.
Batteries are cheap enough to buy 2 packs and run them in parallel for more run time.
Thanks for the great analysis Bert and guys, I'm a noob really but I've got a 4.8ah ebay cell pack, one socket for use/charging with a 1a charger. Its to run a small screen so the wattages should be totally fine and not strain. The manual with the battery is awful. It recommends: plug charger into mains (red led on), turn battery switch to on position, connect adaptor (should turn the led to green, indicating charging) then at least 8 hours until "the green light is off". I've not tried a full charge yet but will update, because its useful to help out. what actually happens is the charger is plugged in (led is green). turn battery to on and connect, the led goes bright red. leave the battery to off and it stays green. i will come back with a resolution to my thinking when ive worked it out ~ Len
I too was tempted by this battery pack to power a suitcase boombox, I take it this won't last long?
I had a 4800 maH version I got on eBay in 2012 that worked great and lasted at least a few hours, used with an amplifier for my backpack speakers. However by early 2013 it was worn out. I ordered another one, but it was different and smaller, and couldn't seem to handle the demands of the amp at decent volumes, as the current would stop and start. Turns out it's the same one, DC 12680 as the OP.
Unfortunately eBay did not retain the info on where I got my original one. This one looks more like the one I originally bought, that doesn't have the blue plastic wrap. It's a bit more at $33, but rated 9800 maH. http://www.ebay.com/itm/151335897900
This one is much cheaper, and is 6800 maH supposedly - http://www.ebay.com/itm/281074691904
I just wish I could just buy one in the U.S. so I don't have to wait as long as a month. It's just a battery, isn't there anywhere else we can get these things???
i have bought two of these packs from ebay china and they are absolute rubbish...the last one was rated at about 9500 ah and was faulty so i took it apart and two of cell packs were faulty...there were six packs inside...each rated at 2100 ah....3 pairs soldered in paralell giving 4200 ah then the 3 packs wired in series giving just under 12volts...so the rated 9500 ah is crap !!! it can only be 4200 ah as the 3 pairs are wired in series....i tried a 12v pack on my metal detector and it failed so quickly even only drawing 120 mah...these chinese packs are absolute rubbish...i will not buy again.
Well, it turned out that it actually IS a 'too good to be true' device in my case.
Just got the blue 12V/6800mAh version from ebay and replaced a 7Ah lead acid battery, which is powering a DTA-1 Amp plus a seperate AirPlay Adapter hooked to a DC converter in a mobile Boombox.
I can't tell what exact current the Amp/Dolry match is drawing but I started playback fully charged at 12.48V and when I stopped after 7 hours continous playing it still showed 11.25V. The lead-acid brick drops below 11V after about 5hrs so it's far beyond my expectations, in particular after reading about all your experiences. I'm really happy with it, just hope this thing lasts for a while.
The whole thing with this mAh rating is that they're almost always given als the sum of the mAh ratings for the individual 3,7V cells, in this case probably 2200 mAh cells.
That's a miscalculation, because as these are 3 cells in series, the voltages add up (3 x 3,7V = 11,1V) but ofcourse the mAh capacity doesn't ALSO add up.
Unfortunately this mAh ( @ 3,7V) has become the standard way of advertising capacity. It would be much better if the capacity would always just be advertised in Wh (occasionally, it is).
Anyway, once you know this, it becomes easier to figure out what the product you're going to order is going to deliver in terms of capacity.
In your case, once past the fog of advertising terminology, that battery actually does a pretty good job of delivering 2200 mAh at 11,1V for a reasonable price.
Just one more thing, if 11,1V is too low for your applicance, look for a pack with an output regulator. These are usually labelled "multivoltage" and have a 4-cell inside (14,8V) so they're capable of delivering real 12V power. Ofcourse, you'll be paying more.
Thanks for making this conclusion because I was about to spend $60 on a 12v 12a lion battery for my home made boom box drawing 50w
And up to 1.29a for the 3.1a 5v car charger this will save me a lot of money thank you
I have 3 of these which i use for camping.
i have run my 15 inch lcd tv (at home) on one as a test.
It will power it for a few hours (2.5 to 3), before the battery auto cutoff at around 10.6 volts.
The battery fully charged is 12.6 volts.
I consider the batteries excellant both in power, weight and price.
the one i got was a dud after a few weeks. If its too good to be true then you know your $$$ will go to waste
Bought one of these batteries a few months ago, after two charges and one months use the battery no longer holds charge and discharges itself without any load from 12v to 8v in about 1 hour. The battery is no longer usable. what a piece of garbage, next time i will use a proper SLA, at least they are reliable and actually give a real mAh reading, not the fake mAh reading you get from chinese ebay batteries
These batteries are absolute trash, avoid at all costs. I disassembled the 3000mah version, and underneath the blue plastic on the outside, is a CARDBOARD BOX wrapped in tape, which contains 3x QMobile (made in Pakistan) CELL PHONE batteries at 3.7v 1400mAh each all soldered together. There is also no short circuit protection or any circuitry to prevent short circuits, overcharging, over discharging etc. what so ever. The batteries are soldered straight to the switch and led, using MASKING TAPE to insulate the wires, not even electrical tape, not even heatshrink, and the soldering is extremely poor. One of the three cell phone batteries failed after five recharges. Absolutely disgrace that they are selling these, it is a bodged battery, likely not even safe
I got one of these batteries to try and was expected the capacity to be overstated based on the volume of the battery- and it was. Their are 3 cells in the pack and what they do add the capacity of each of the batteries to give the larger number when what they should quote is the capacity of a single cell in the string of cells. The capacity would be correct if the cells were connected in parallel which would only give the voltage of a single cell.
It's figures either made up by someone who has no idea of electrics, a deliberate lie to make the packs sound better than they are, or something between the two. I think it's the third- they are sold by sellers who don't understand what they are selling and are just quoting specifications given be a distributor or manufacturer who is being deliberately untruthful.
The DC connectors on the battery are not good enough for a demanding application like powering lights on a motorcycle. The connection is not reliable. I cut off the DC connectors and soldered on SAE connectors, which work much better. Problem is, the WIRES ARE TINY--26 AWG or something like that, so it makes it very hard to solder.
The Lipo I bought from HobbyKing is much better quality and about the same price per capacity (considering this battery is actually 2300 mAh).
I completely agree.
I opened mine and couldn't believe just how bad construction was. I ended up going a different way too- I bought 18650 cells and built my own packs. I'd had this in mind anyway before looking at this shockingly bad pack. I had intended to power 12V leds on my bike but it was hopelessly inadequate for that job- the T6/U5 led lights are too much for it.
I still haven't found any use for this pack yet- maybe it'll be a good bin filler?
The reason that the measured capacity is less than the advertised capacity may be that some unscrupulous manufacturers use a lower voltage than 12 volts to derive their amp hour rating. These devices should be described with a watt-hour capacity (rather than mAh) to assure honest and comparable product selection.
the hour element is covered in the false claimed specifications- mAh. Your 'better' way is just this multiplied by the Voltage. And it's STILL a false figure however you want the capacity presented.