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Old Jul 03, 2006, 08:08 PM
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Rick,

I measured the temperature rise during charging on the first cycle. It was about 9 degrees C. Post No. 27. My feeling is that that's too little to need graphing, which is quite a time-consuming proceedure.

As you point out, departures from the manufacturer's routine, e.g. charging longer than 15 minutes, will likely produce unwelcome results.

For longer-term "float" charging, the manufacturer recommends 3.45 volts; 4.2 would likely be disastrous.

T.M.M.,

It's possible that later cycles reflect some adaptation of the cell to the charging routine. I don't know.

- RD
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Old Jul 03, 2006, 08:28 PM
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Tomorrow we'll see how well the cell tolerates 10 discharges at the manufacturer's specified absolute continuous amperage limit: 60 amps (26C).

Ron,

How do you guys charge your boat batteries?

- RD
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Old Jul 04, 2006, 03:21 AM
HammerHead H2o Racing
Deltona, Florida
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RD

we're using an Astroflight 109 at present, charging at 3 amps and terminating the charge at 3.8v per cell... a couple tricks involved and monitoring of the charge is necessary

we're testing with 2s, 6s, and 10s packs in parallel [I.M.P.B.A. provisional class N3, Q1, and T1]

we have a Schulze isl 6-330d w[V8.41] software ordered but haven't received it from yet...

Ron
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Old Jul 04, 2006, 04:54 AM
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Thanks, Ron.

For the (many) guys who own the Astroflight 109, would you feel comfortable disclosing the tricks?

For guys who are comfortable with manually set voltage & amperage for charging Lithium cells, I did the graphs for this thread with this unit:
http://radios4you.com/mastech-hy3010E.html

For parallel charging requiring higher amperage, I use the Mastech 3020.

- RD
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Old Jul 04, 2006, 05:34 AM
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Tony Rogers
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Very interesting. These cells seem pretty tough so far. Looking forward to the high discharge test. A 1C capacity check might be interesting at that point.

Thanks for the tests RD.
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Old Jul 04, 2006, 02:41 PM
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Victoria, BC, Canada
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Quote:
Originally Posted by RD Blakeslee
Rick,

I measured the temperature rise during charging on the first cycle. It was about 9 degrees C. Post No. 27. My feeling is that that's too little to need graphing, which is quite a time-consuming proceedure.
I saw that, indicating not much heating, but I was wondering whether the temperature is rising rapidly at 4.2V during the CV stage. The real question is How long do we have at 4.2V and (say) 2C currents before the cell is at risk?

Rick.
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Old Jul 05, 2006, 08:44 AM
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Rick,

When I held the cell beteen my thumb and forefinger on the metal end discs, I observed the temperature to rise more rapidly toward the end of the CV phase.

Determining the effect on the cell when charged outside the manufacturer's prescribed protocol would involve testing each protocol, I suppose. Also, I don't know whether degradation is a function of the length of time it's subjected to 4.2 volts, independently of temperature.

- RD
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Old Jul 05, 2006, 08:52 AM
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Capacity loss is about 0.1 AH, when the cell is fast-charged and discharged 10 times @ 60 amps.

While the capacity loss trend is consistent, Voltage maintained and finish temperature were random and appear to be the result of off-charger variations in voltage and temperature.
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Old Jul 05, 2006, 12:19 PM
Spokane Washington
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Wow! That cell is really taking a beating pretty well.

-Austin
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Old Jul 05, 2006, 12:37 PM
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Austin,

It's taken the beating (going a little above "absolute maximum" temperature, for example) without making me nervous like a LiPo would around its limits.

One could wish its physical density (weight) were lower, but as far as I'm concerned, I wish even more that Hoppy had never had to catalog all those LiPo fires.

It will be interesting to see what Saphion is coming out with.

- RD
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Old Jul 05, 2006, 01:13 PM
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I agree. I wish that there was more interest in safety and less interest in performance. That does not seem to be the case in the battery business. People seem to be willing to deal with the risk for a slight improvement in performance. I do think that these new products will prove to provide more life cycles at the higher discharge rates than the lipoly cells. I agree that if we could get the weight of these cells down to 50g or so then they would be a winner.

I am nervous about bringing them in as I don't know how popular they would be in the current form. Do you think we should wait a bit longer for the technology to improve or wait to see what Saphion does next?

-Austin
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Old Jul 05, 2006, 06:15 PM
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Austin,

I'm at a loss to help you with marketing decisions. I just can't guess what your volume might be, or whether the new Saphion might make the A123 passe for eflight. As always, price will be a major factor.

Do you think running a poll might help? Getting some idea how many RCGers have bought DeWalt power tool packs to disassemble might help, I don't know.

- RD
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Old Jul 05, 2006, 06:26 PM
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My first question is can you buy from A123 in volume and be able to match the price they are offering. Are you going to offer packs? Someone on this thread has told people that A123 is not interested in dealing with a middle man and wants to sell direct to the public. I don't see why you could not sell these cells and packs if they will sell to you.

However, it looks as if Saphion has as good a quality in a smaller cell, they may make a larger one. Or, A123 may already be working on the next cell. I bet Waterdog49 knows the answer to the A123 question.
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Old Jul 06, 2006, 05:15 AM
Giz
Tony Rogers
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Quote:
Originally Posted by austinelse
...

Do you think we should wait a bit longer for the technology to improve or wait to see what Saphion does next?

-Austin
Austin,

I think these types of cells will become very popular in time but maybe not yet. I think the issue is weight.

I now use only lithium based cells. For aerobats (.40 size) I use lipos and for electric gliders and pusher jets I use Saphions.

I don't use the Saphions in the aerobats because they would be too heavy and expensive for a reasonable duration. In the glider they are fine. Because they can put out a lot of power, you can stick with 1p and still get a reasonable flight time. In the pusher jet, 5 minutes is enough!

I like the Saphions because I allow myself to charge them indoors, which is something that I would never do with lipo packs. My lipos are only ever charged out on the patio.

So, at the moment, I don't see these cells replacing lipos because a large enough pack to give good duration in the majority of models would be (much) heavier and maybe more expensive than lipo.

What we really need is a lightweight version of these cells that can do 5-10C average with 20C bursts and still be charged at 10 amps . That would allow a 2p pack configuartion to give up to 80-90 amps for aerobatic manoeuvres and flight times of 6-12 minutes.
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Old Jul 06, 2006, 05:42 AM
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Quote:
Originally Posted by Giz
Austin,

I think these types of cells will become very popular in time but maybe not yet. I think the issue is weight.
Tony: I don't see the issue as weight, but mind-set instead. A lot of the guys using LiPo's are using them in small foamies, where weight *is* a big issue. However, with bigger (cheap) motors and ESC's coming out of China, I think we are going to see e-powered birds increase in size - and the bigger (.40 to .60) birds will become more popular with the club flyers. This is where we will see the Saphions, A123's, and the E-moli's come into play. Will it become a huge following? I dunno - my crystal ball told me to bet on Portugal for the world cup

The Park-flyer guys will stay with the smaller/lighter equipment.

Brad
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