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View Full Version : Battery Capacity Comparison - Rated VS Actual


Volt
2008.03.17, 05:56 PM
I recently bought a Maha C-9000 Wizard (excellent piece of equipment) and some 4 packs of a few different brands of batteries. I know that most batteries actual capacity is less than rated capacity, what I didnít know is how much variation there is between these numbers of different brand batteries. My purpose for this comparison is to find the latest technology (as of 2008) NiMH batteries that will really give the longest run time. I have been using the Sanyo Eneloop batteries for my TX because of their low self discharge (they last a long time in my KT-18), but Iím sure they would work good in the car as well.

The following capacity results are the average of 4 batteries (of each brand) that were brand new out of the package and then put through the Break-In cycle (IEC standard capacity measurement) of the C-9000. The percentage is measured capacity over rated capacity.


Break - In

Sanyo Eneloop 800 mah
813 mah (101.6%)

Sanyo "Superlattice Alloy" 1000 mah
984 mah (98.4%)

Better Power 1000 mah
978 mah (97.8%)

Team Orion 1100 mah (RT)
920 mah (83.6%)


I realize that a Mini-Z draws a lot more power than 200 mah (break-in cycle discharge rate). After a few cycles of each pack, I put them through the refresh and analyze mode with a charge rate of 1A and a discharge rate of 1A. The following results should be closer to what you would expect from actual driving.


Refresh & Analyze (1A charge, 1A discharge)

Sanyo "Superlattice Alloy" 1000 mah
952 mah (95.2%)

Better Power 1000 mah
956 mah (95.6%)

Team Orion 1100 mah (RT)
911 mah (82.8%)


I am a little disappointed in the performance of the Team Orion batteries, especially since they are advertised as ďRun TimeĒ batteries. It seems they claim more capacity than other brands and produce less capacity.

Of course capacity is not everything, different brands may provide more Ďpunchí or have a more stable voltage (linear power curve) at different points in the cycle. I have not noticed any difference so far in driving characteristics between the brands listed above. However Iím still a novice/intermediate driver that races stock class. I have a 2.4 GHz setup running a Speedy í07 motor that I almost never bring to full throttle. All of the above batteries give me at least 20 min run time with no noticeable power drop, and at least a 40 min run time total.

If anyone has additional brands tested in the same manner, please post the numbers.

Also, does anyone have information about the pros/cons of a tiny trickle charge after cycle completion? I read somewhere that batteries for R/C purposes should not be trickle charged at all, but Iím wondering if this is true for every case. It seems to me that this would be more of an issue for cells that are charged in series (like a battery pack for larger scale) and not so much for independently charged cells (as the C-9000 charges).

byebye
2008.03.17, 06:37 PM
Out of the box my Team Orion 900mah charged to 1300 mah with a 200ma charge rate. I got the same result from the 1000mah Duracells: 1300mah@200ma charge.
Kris

Volt
2008.03.17, 07:13 PM
Thanks for the info Kris. You mention a 200ma charge rate. Is the 1300 mah capacity based on a discharge cycle?

I think the only way to determine actual battery capacity is with a discharge cycle from a fully charged cell.

For example, the break-in cycle charges to 1.6C of the battery. In the above examples that would be charged to around 1600 mah. Some of the charge is lost as heat and other inefficiencies, therefore the discharge numbers are the ones to trust. The battery can 'accept' more energy than it ends up putting out. Does this sound right?

byebye
2008.03.17, 07:28 PM
No that was just drop it in. I have discharged them and found them to charge higher than the actual rating.

One thing I've noticed is the difference between a cycled battery and a non-cycled battery. I think I prefer to only discharge and charge a battery insteand of doing the 18+ hour break-in cycle.

Kris

leonen
2008.03.18, 07:41 AM
Volt,
I recently bought a Lacrosse Charger - beautiful artifact - and started to test and refresh all my packs. And some new ones.

Here are some results:

Atomic Mods (branded as 900): 458 Mah.

Eneloop: 836Mah

Intellect: 612 Mah (an old pack - a year of every weekend reacing)
712 Mah (not so old)
808 Mah (a brand new pack)

Team Orion (900): 799 Mah (after a few break in cycles)

Powerex (1000Mah): 985 Mah.

The Team Orion 1100.... after testing brand new pack I got around 750 Mah!!!!

I'm also very dissapointed with the capacity shown by these, but they have a incredible kick on track! Anyway, they don't last very much yet. I've read that you need about 50 cycles before the batteries (especially higher capacity ones) are formed inside and capable of delivery what they are built for.

So far, Intellect and Eneloops are my best packs.

We'll se as time goes by how the rest perform.

byebye
2008.03.18, 01:00 PM
There was also the discussion of internal resistance of different batteries. Even though a higher capacity is there does it drain fast or slow? I think you need to have a special battery charger that will give you that info. I know Jonny from RSR has a charger that does that.

Kris

mk2kompressor
2008.03.18, 01:52 PM
much more cell master:)

jonnys flash one:eek:
http://www.risingsunracing.co.uk/images/Cell%20Master%20and%20Supply%20S.jpg



1 cell at a time for IR though,but we are both still experimenting with them;)

Volt
2008.03.18, 11:14 PM
Thanks a ton for posting those numbers leonen, it looks like our results agree more or less on the Eneloops and the Orion 1100s. I was curious how the Intellects faired as well since they are so popular. It's true that after about 50 cycles the capacity could increase a bit.

Kris, thanks for touching on the topic of Internal Resistance. That is the missing piece of the equation and the part that can change driving characteristics because at full charge the voltage is stable (despite the claim of a 1.25V nominal cell).

I tend to be a quite technical person sometimes. It would make more sense to me to quantify the quality of the battery that can give you more torque and speed than a different battery of the same capacity. Using hard data to back up the subjective feeling of driveability. I think your exactly right Kris, the extra 'punch, kick, karate chop' can be explained by more current flowing to the motor at a given instant caused by a lower IR within the battery.

I realize that IR is a difficult measurement to obtain. If a couple people who happen to own phat expensive charger setups like Jonny (nice pic btw) would be generous enough to post some 'out of the package' IR numbers of different brands for comparison, that would be greatly appreciated. It would probably be best to start a new thread in that case so the discussion could take off. I don't expect much, one cell at a time, ouch.

schmenzer
2008.03.19, 12:37 AM
Guys,

I have both the LaCrosse and the Maha C-9000 and a have found that with the same set of batteries I get different indicated charged capacities. Usually about 100mAh lower on the Maha. Does anyone know how accurate these mid-line chargers are? I like them both and the performance of the batteries charged by either one seems fine.

I usually discharge my batteries on the PN Racing AAA Discharger so, normally, when I plug the batteries into the charger they are at .9 Volts or so.

After the discharge I hit the batteries with either 700mAh from the LaCrosse or 1C from the Maha.

Greg

mk2kompressor
2008.03.19, 01:31 AM
volt,we are both using the same charger(jonny's is a bit more "bling" than mine)
hopefully we will have some time soon to test our cells fully:D
so far i have done 13 packs of duracell 1000 and 3 packs of duracell 900,
the best pack of 1000 i have are(all matched by mah on the maha);

959mah
958mah
959mah
959mah

the 900's

890
897
889
891

i dont have the time figures with me at the mo but will post them soon

greg,
the maha is quite acurate,i found the figures to be very similar on the muchmore.
a different charge rate will give different results,i find a longer charge(lower rate)gives them a cleaner more linear discharge(esp after dropping them to .9 on a discharger)

Volt
2008.05.11, 12:04 PM
I recently bought 3 packs of Intellects since they come so highly recommended. Here are the testing numbers:

Break - In

Intellect "High-drain Type" 750 mah
Pack 1 - 741 mah (98.8%)
Pack 2 - 738 mah (98.4%)
Pack 3 - 737 mah (98.3%)

Refresh & Analyze (1A charge, 1A discharge)

Intellect "High-drain Type" 750 mah
Pack 1 - 748 mah (99.7%)
Pack 2 - 751 mah (100.1%)
Pack 3 - 746 mah (99.4%)


It looks like the rated capacity numbers are very close to actual. This makes it easier for me to believe the other claims this battery makes: 10C or 7 amp discharge. :eek: These definitely seem to dump power to the motor in quantity, they are the fastest batteries I currently own.

They still last around 20-25 min in my ASF 2.4 ghz car running either an Atomic stock or a PN Speedy 07. Even with a heavy throttle finger they never seem to heat up. My motor can get quite warm, but these batteries stay cool at higher draw rates.

The Intellects are not designed to hold a charge for long, best to charge them the night before or even the day of race day.

My suspicion is that these batteries have an incredibly low IR compared to other batteries. It is likely that as battery manufacturers keep adding more capacity, the IR goes up in turn as they are trying to fit more electrons in the same compact space.

My best performance longer run time packs are the Sanyo 1000 mah with the Better Power 1000 mah as a close second. Both of these brands provide good punch and a fairly linear power curve throughout the cycle.

mk2kompressor
2008.05.11, 12:12 PM
ive just broken some 750 intellects in too:)
same results as you,very close to the manufacturer spec and they give the most punch out of all my batt's so far.

R1WURKS
2008.06.08, 06:31 PM
Nice to see you guys do some heavy testing.