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Old Aug 07, 2006, 09:48 PM
Southern Pride
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Sanyo 2700 NiMH AA versus Energizer 2300

Well my Energizer 2300s have served me much better than the 2500s have but Sanyos allways seem to be the King of the hill so I purchased some of the latest Sanyos to give them a try. Initial testing has been very good.

A snip from another post of mine on an 8 cell pack of these Sanyo cells.

Quote:
Second cycle on Triton charged at 1A ,started discharge at 1A five minutes after charge ended .
Voltage droped to 9.56 at 1300 mAh delivered and is holding.
Voltage droped to 9.30 at 2100 mAh delivered. . This is equal to approx.. 8 - 1/2 hours of continue on time with most RC Transmitters. I have no doubt that at the normal 250 mA drain rate and with some off time between flight the voltage would hold up even longer.
Dicharged to 7.2 volts 0.9V per cell) 2564 mAh / 153 minutes . One minute after end of discharge battery rebounded to 9 volts.

8-13-06 Added a second graph showing results after 10 days storage.

Yes there is only 7 days difference in the posted dates however not all Sanyo 2700s were charged at the same time.


Possible interesting data point:
After discharge (10 day delayed) I recharged this singlre cells at 1A on Triton NiMH 4 mV peak setting. Room temp. 83F from 0 to 2400 mAh temp. only reached 85F. At 2500 mAh temp. was 95F at end of charge 2691 temp. 112F.
I will never understand how some can state that temperature is not a good indication of state of charge during charging.


Charles
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Old Aug 08, 2006, 07:53 AM
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Nice!

Great work Charles!

thanks,
Steve
www.battlepack.com

Quote:
Originally Posted by everydayflyer
Well my Energizer 2300s have served me much better than the 2500s have but Sanyos allways seem to be the King of the hill so I purchased some of the latest Sanyos to give them a try. Initial testing has been very good.

A snip from another post of mine on an 8 cell pack of these Sanyo cells.



Charles
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Old Aug 08, 2006, 08:34 AM
Southern Pride
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Thanks Steve being in the business you are totally aware as are other graphers but most viewers have little idea that one such charge,discharge and recharge for a single cell requires approx. 8 hours. True it is not intense physical work but still very time consuming. Lucky for me I enjoy exploring the wonderful world of rechargeable cells.

A couple of details which some may over look. While both cells were charged at 1A the Energizer 2300 was discharged at 1A and the Sanyo 2700 was discharged at 1.3A. Reported tested capacities were Energizer 1.71Ah (1710 mAh) and Sanyo 2700 2.37Ah (2370 mAh).



Best price I am aware of for the Sanyo's $2.75 ea.@

http://www.battlepack.com/loosecells.asp

Charles
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Old Aug 13, 2006, 09:41 AM
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Delayed discharge graph added to first post.

Charles
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Old Aug 24, 2006, 06:51 PM
Southern Pride
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Sanyo 2700 AA NiMH Time / volts after 3 weeks.

Sanyo 2700 single cell 3 weeks since charge.
Discharge rate 250 mA. same as used by many RC Transmitters.

Start 1.22V
30 min. 1.21 * 8=9.68
60 min. 1.21
120 min. 1.20 * 8= 9.6
180 min. 1.18 *8= 9.44
240 min. 1.16 * 8= 9.28 Point at which many Transmitter reach low voltage alarm.

These times / votages are not bad but they fall well short of the past results I have obtained with Sanyo 2500 green sleeve indudstial(?) cells.

From an old post of mine on the Sanyo 2500 gree sleeves.

Quote:
02-06-06 Sanyo 2500's after setting for 58 days
Time / Volts
Start / 10.1
5 min. / 9.8
30 min. / 9.8
60 min. / 9.7
120 min. / 9.7
180 min. / 9.6
240 min. / 9.5
300 min / 9.4
330 min / 9.3 Low Voltage Alarm
Charles
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Old Aug 24, 2006, 06:58 PM
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Question for you....

You charged these and let them set for 3 weeks and have 4 hours of charge in them?, cool.

I wonder if they ever had 2500mah cells with the fancy shrink, I don't recall ever seeing it. I would not know of any difference or why the 2500mah cells were better. We did sell these however and I think we can still get them.

thanks for the testing.

Steve


Quote:
Originally Posted by everydayflyer
Sanyo 2700 single cell 3 weeks since charge.
Discharge rate 250 mA. same as used by many RC Transmitters.

Start 1.22V
30 min. 1.21
60 min. 1.21
120 min. 1.20
180 min. 1.18
240 min. 1.16 Point at which many Transmitter reach low voltage alarm.

These times / votages are not bad but they fall well short of the past results I have obtained with Sanyo 2500 green sleeve indudstial(?) cells.

Charlers
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Old Aug 24, 2006, 07:04 PM
Southern Pride
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Quote:
I wonder if they ever had 2500mah cells with the fancy shrink,
http://ripvan100.com/products_sanyo2500mah_IG.htm


Those were the ones which were being counterfited ,remember?


Charles
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Old Aug 24, 2006, 08:19 PM
Southern Pride
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My Redneck findings/ observation...
Most is not all high capacity AA NiMH cells will have a higher self discharge rate than lower capacity ones. Exactly where the tide turns is hard to judge.
Some 2300 s will kick 2500 and 2700s backside when it comes to delivering capacity after entended storage ,the green sleeve Sanyos seem to be different (better) than the others..
The eneloop cells are reported to be extremely low self discharge however they are also only approx 2000 mAh which makes me wonder how much better they are than other 2000 mAh cell.
There are several others claiming to have similiar cells in development.
Now if someone can come up with a 2000 mA AA NiMH type that retains 85% plus for one year at room temp. and get the price down below $5 per cell.

Charles
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Old Aug 24, 2006, 08:41 PM
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Yes

eneloop, yes, can't get those yet....bummer.

thanks,
Steve

Quote:
Originally Posted by everydayflyer
My Redneck findings/ observation...
Most is not all high capacity AA NiMH cells will have a higher self discharge rate than lower capacity ones. Exactly where the tide turns is hard to judge.
Some 2300 s will kick 2500 and 2700s backside when it comes to delivering capacity after entended storage ,the green sleeve Sanyos seem to be different tahn the others..
The eneloop cells are reported to be extremely low self discharge however they are also only approx 2000 mAh which makes me wonder how much better they are than other 2000 mAh cell.
There are several others claiming to have similiar cells in development.
Now if someone can come up with a 2000 mA AA NiMH type that retains 85% plus for one year at room temp. and get the price down below $5 per cell.

Charles
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Old Aug 25, 2006, 11:22 AM
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Hello Charles,

An update on the Eneloop cell testing...

After 90 days of room temperature storage, they have about 88% of their initial capacity.

Tom
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Old Aug 25, 2006, 11:32 AM
Southern Pride
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Thanks for the update Tom. I am still not 100% convinced they are that much of a practical improvement / advantage over high quality NiMH cells.
My logic iis a bit like this. If they(eneloop) are 2000 mAh and retain 90% for 60 days then they are marginally better than Sanyo 2500 NiMH cells stored for the same length of time.
In some applications I can see where extremely low self discharge would be worth the high cost per mA. but not many. A set of these at $40 would be a more logical choice than a $60 LiPoly in a Transmitter but NiMHs are still so much bang for the buck.
Have you compared these to the Sanyos 2500s down to 1.15V per cell at around a 0.5A load?


Charles
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Old Sep 12, 2006, 09:28 AM
Southern Pride
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Sanyo 2700 NiMH update

Well these Sanyo 2700 NiMH AA cells are great fresh off of charge and even the 21 day delayed test above was very good but the last round of extended storage testing was not so good.

An 8 cell pack last charged on 8-3-06( 39 days ago) was discharged on a Triton at 0.3A .

9.41 volts at 5 min.
9.35 volts at 10 min.
9.32 volts at 15 min.
9.30 volts at 22 min. Low voltage alarm point for many RC Transmitters.

While this is not terrible performance for a battery charged almost 6 weeks ago and stored at room temperer I have seen / had better results. My Prior testing of Sanyo 2500 Green Sleeved was much better. Over all it sure seems like many of the 2500 mAh plus NiMH AAs have a self discharge rate problem much worse than the 2300 mAh and below ones.


Snip from a post on the Sanyo 2500 Gree sleeved

Quote:
02-06-06 Sanyo 2500's after setting for 58 days
Time / Volts
Start / 10.1
5 min. / 9.8
30 min. / 9.8
60 min. / 9.7
120 min. / 9.7
180 min. / 9.6
240 min. / 9.5
300 min / 9.4
330 min / 9.3 Low Voltage Alarm
Charles
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Old Sep 12, 2006, 10:42 AM
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So, your saying the 2500mah cells have the best voltage retention? However, fresh off the charger the 2700mah cells are best capacity wise? This is good info to have.
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Old Sep 12, 2006, 11:04 AM
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We can still offer those 2500 cells for $2.25 a cell.
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Old Sep 12, 2006, 11:25 AM
Southern Pride
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Quote:
Originally Posted by sjslhill
So, your saying the 2500mah cells have the best voltage retention? However, fresh off the charger the 2700mah cells are best capacity wise? This is good info to have.

Based on all of my high capacity NiMH AA consumer cells that has been the case.

You know a thing or two about how cells are constructed. The simple fact is that for a give physical size cell to increase the capacity the separators have to be thinner. This most always leads to higher self discharge rates, more separator failures,development of more micro shorts (whiskers) etc.
The Sanyo 2500s with the green sleeves such as is normally used on their industrial (OEM) cells seem to be the only ones over 2300 mAh which can maintain great capacity after prolonged storage.

I really do not see the need in a Transmitter battery being able to hold a charge for weeks on end. I do like mine to last me several days of flying without having to watch the Transmitter voltage display like a hawk. These 2700 meets that requirement easily.

Quote:
Sanyo 2700 single cell 3 weeks since charge.
Discharge rate 250 mA. same as used by many RC Transmitters.

Start 1.22V
30 min. 1.21 * 8=9.68
60 min. 1.21
120 min. 1.20 * 8= 9.6
180 min. 1.18 *8= 9.44
240 min. 1.16 * 8= 9.28 Point at which many Transmitter reach low voltage alarm.
IMO anyone who can not find the time to charge their Transmitters every three weeks needs to slow down a little.

My extended storage test are just a simple way to determine the true self discharge rate of the different capacities and brands. There does seem to be a coalition between the cells with a high self discharge rate and cell failures but then my testing is limited.
The results of my 21 day test and 39 day test do not match well at all. The sigle cell used at 21 days perhaps was one of the best and perhaps the 8 cell test at 39 dya had one of the worse cells in it. All cells were very closely match when new after being cycles several times.


Charles
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