PCB for Battery Pack
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DIWdiver
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Impressive. Thanks.
OK, today I tested the Red UltrFires from DX which come with PCB and rated at 2600mah. I tried a 2600mah discharge rate and the cell went to zero volts pretty wuick. Assume the PCB kicked in. I then tested another one at 1 amp and only got 1700 mah. Now I am doing one at .5 amps to see how it does. These don;t seem to be very good.
I can get some unprotected 3100 mah (panasonic) cells for around 7 dollars. I weld my own battery packs(build them too) so it would be okay for me to use some without built in pcb and tabs to solder onto. I don't trust anything with fires at the end (haha but that guy 350xfire is okay). They never work as described.
Also, the closer you are to driving voltage, the higher your efficiency (generally). Though there are some guys around here who have a VERY efficient driver the size of a 1 dollar coin and it's a buck driver not boost. I wanna say 93-98%? Better than the usual 87%
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After testing 3 of the UF reds with PCB I can honestly say, I'll never buy those again. At .5a discharge rate, the best I did was 1.7ah. These cells are a few years old but not used very much. I am now testing the blue TrustFires to see how they compare. These are 2500mah.
I was under the impression that the 3100 mah batteries were only for low current use and they will lose a lot of capacity when driven hard.
I am impressed that the Sanyos provided 2.4ah after the first charge and up to 5 amps draw. I am convinced that these are THE cells!!!
I was under the impression that the 3100 mah batteries were only for low current use and they will lose a lot of capacity when driven hard.
I am impressed that the Sanyos provided 2.4ah after the first charge and up to 5 amps draw. I am convinced that these are THE cells!!!
Seeing as most of my cells don't see a 5a draw, I don't worry about that. Normally it's .5C to 1.0C discharge. I prefer it like that for less strain on my packs thus longer lifes. My standard is to stay at 3 hours of run time (.3C).
Still with a 1 hour run time and 2 batteries, that's a 1C draw. For those who don't understand, 1C would be 2.4 Ah for a 3.7v 2.4 amp battery. So therefore, your test is a (5amp) 2C ish discharge test (Which I'm sure you know).
Point is, for scuba diving applications, testing past 1C is unneccessary.
That is abosolutely correct for a single XML or soemthing similar being run with 2 18650. However, I was trying to find the best-ish battery for the 8XML video light and those are can pull 6 amps depending on battery/LED configuration so I wanted something better.... I am running the XMLs 4S2P and the batteries 6S3P. I think for the extra $1 the Sanyos beat pretty much anything out there. So from now on, I'll be using those.
I was curious about the math so I wrote out some figures.
Roughly 80 watts plus .2% for driver inefficiencies so conservatively 95 watts. So 6*3.7= 22.2VDC then 3*2.4=7.2AH 22.2*7.2= 159 watts battery power. 159/95= 1.67 hours (1 hour 40 minutes) Weight 1.825 lbs with 18 cells. Volume, 18.1692 cubic inches
Now with the 12 count 3.1 panasonic cells. 2*3.1= 6.2*22.2=(130.98 at 2950 from 1.c discharge)137.64/95= 1.44 hours ( 1 hour 26 minutes). Weight 1.2 lbs with 12 cells. Volume, 12.1128 cubic inches.
http://industrial.panasonic.com/www-data/pdf2/ACA4000/ACA4000CE254.pdf
I suppose there are the down sides to everything, and to each his own preference. But I do love panasonics.
Not arguing against your logic. I just haven't used Panasonics! I'll have to put them to the test. I am just impressed at running a cell at 5 amps and getting the same ah as I got at 1 amp!
Say Sanyos are 2 for $11 that's .0022 cents per mah
Panasonics are 2 for $18 kaidomain- that's .0029 cents per mah (that is if you truly get 3100 mah... chances are a couple of hundred short)
So the price difference may be justifiable as long as the application is right and the Panasonics fit the discharge rate requirement and if you truly get 3100 mah.
Say Sanyos are 2 for $11 that's .0022 cents per mah
Panasonics are 2 for $18 kaidomain- that's .0029 cents per mah (that is if you truly get 3100 mah... chances are a couple of hundred short)
So the price difference may be justifiable as long as the application is right and the Panasonics fit the discharge rate requirement and if you truly get 3100 mah.
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Exactly my point! Depends on application. If you buy by the bulk though, you save. Its 6$ a cell if you buy yourself from a dealer. I quoted 7 because if I bought them, I would need a little something for my time. So to me, that adds up.
OK,o next was a couple od DX Blue 25500, the C-sized LiIon. Keep in mind that, due to the PCB, these are bigger than C cells and they will not fit into a C Mag... After testing 2 of these, my conclusion is that they are a rip off, only getting about 2500mah for the $8-9 each I paid for them. Now, the only thing here is if you NEED the form factor for convenience, etc. Otherwise buy the 18650 and save $3-4 per cell. Oh, and I tested at 1.5 amps since typically when using these we are feeding a 2S LiIon module for an XML or something like that which runs at 3 amps at around 3.x volts or around 1.5 amps at 7.4 v... More to come.
Next the Blue 2400mah TrustFires... At 1 amp, tested at 2000mah... At 2 amps 1800mah.
Moral of the story, buy name brand batteries! Skip the China crap...
The last ones I am going to test will be the unprotected green ones sold by DX. Those have been consistent in capacity for me, although still overrated.
Moral of the story, buy name brand batteries! Skip the China crap...
The last ones I am going to test will be the unprotected green ones sold by DX. Those have been consistent in capacity for me, although still overrated.
OK, so I got the Panasonic 3100 mah. As expected, they turn to mush around 2 amps. They do, however, get a solid 2900mah down to 2.8 volts at around 1 amp or so. Overall not bad, but since I am using 8 cells in my can lights, it doesn't matter for me whether I can get more ah. For the price, the Sanyos are the best for me!
I just tested a 2S4P pack using Sanyos and got a bit over 10ah (tested at 4 amp rate)... This means each cluster of 2 cells is getting 2500mah. AWESOME! The green DX batteries never gave me more than about 8ah and most of the time 7.5 or so... From now on SANYOS for me. There are also USA sources which charge reasonbable prices so I don't have to wait 3 weeks to get them in.
I just tested a 2S4P pack using Sanyos and got a bit over 10ah (tested at 4 amp rate)... This means each cluster of 2 cells is getting 2500mah. AWESOME! The green DX batteries never gave me more than about 8ah and most of the time 7.5 or so... From now on SANYOS for me. There are also USA sources which charge reasonbable prices so I don't have to wait 3 weeks to get them in.
