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Is 10c 5000mAh package to much?

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Is 10c 5000mAh package to much?

Old 04-09-2010, 04:01 AM
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DagTheElder
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Default Is 10c 5000mAh package to much?

Hi,

The uncertainity is about current used. In my environment it seems that people are charging anything between 3000-3900 mAh into 5000mAh pacages.
Let us use the basis for discharge at approx 80%.

Charge 3000mAh wich is 80% discharge gives 3750mAh capacity battery.
Charge 3900mAh wich is 80% discharge gives 4875mAh capacity battery.

How often are one charging 3900mAh or more??? Is this under conditions that there are no flying accordig to FAI rules?????
or, are we using the best equipment re consumption of current ??????? in the propultion system??????

Will it be safe to reduce battery capacity to say approx 4400mAh and take the penalty if any to discharge (3500 mAH @ 80%) or 85% or so rarerly??????

Weight is an driving issue always!

What capacity do you use for your receiver? Anything between 600mAh to something..........? Capacity to take you safe through 5++ schedules? Average well under 100mAh pr schedule? Weight for this cell approx ??????
A 350mAh battery @ 25gr will be more than enough pr schedule and change it out when you are charging your drive pack. That means one receiver battery package pr drive battery package. Just stick your receiver battery onto your drive battery and save 30-100 grams.

What are your experience????

Best regards





Old 04-09-2010, 10:35 AM
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underdw
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Default RE: Is 10c 5000mAh package to much?

Hi Dag,
I've decided to use 5000mah packs regardless. In practice there is always something I screw up that I want to go back and work on after a sequence.
Maybe for contests 4400, but I make weight with the larger packs.
I use 2 cell 350mah for my Rx. Change it out every 3 flights.

Dan
Old 04-10-2010, 09:30 AM
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DagTheElder
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Default RE: Is 10c 5000mAh package to much?

Hi Dan,
Great to hear that you take full advantage of receiver battery. How many mAh do you charge after 3 sequences. If I decide to change receiver battery together with drive battery i suspect 2c 250mAh will be good, instead of 360mAh. Weight will be a non issue due to weight of cables and contacts.

When you fly P11 only and charge your battery how many mAh do you need to fill back????

I will also like to hear from other peoples experience re this issue.

Thank you

Best regards

Old 04-10-2010, 01:50 PM
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joenella
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Default RE: Is 10c 5000mAh package to much?

Dag

I fly NORDIC and use 2S A123 1100mah as receiver battery, I use about 50 mAh a flight. Weight of the 2S is 78 gr. total, no need for regulator. Do not go to low in cap. as You could risk your plane due to low voltage under heavy load from servo's 250mAh @ 20C is only 5A, I would not risk my plane for a few gr. daved on receiver batterypack.
Old 04-11-2010, 01:11 AM
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DagTheElder
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Default RE: Is 10c 5000mAh package to much?

Hi,
Thanks for answer!
I guess 2c 350mAh @26c will be an good alternative. Especially when it is to be replaced after one sequence together with drive battery. What is equally important is the capacity of drive battery. May I ask what you are using, capacity and re-charging etc?

Ther must be some more people out in RCU that have good/bad experience with capacities of batteries???????

Best regards
Old 04-11-2010, 08:41 AM
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can773
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Default RE: Is 10c 5000mAh package to much?

Hi Dag,

I think its a good idea to always use the largest capacity battery that you can fit and be within the weight limit. Since usually 5000 to 5300 mAh is the typical largest size that is the one that gets used.

My reasons for this are,
- A larger pack needs to run at less "C" discharge which is better for longevity
- For a the majority of its life the pack will almost always be at greater than 37V after a flight, which is better for longevity. The 37V limit is a much better way to see how deep you discharged, the 80% rule is really only valid when a pack is new, as it ages 80% is less and less, where 37V is the stop point at any part of the pack life.
- With the larger pack you have much less chance to ever over-discharge the pack, even on windy or longer flights.
- You can get more flights from a larger pack, as a lipo ages it functionally gives you less useful capacity, so if you start with a larger pack you will get more flights before you need to stop flying it.

Yes you can run smaller packs, but the question I would ask would be, why would you want to use a smaller battery and push it closer to the limit nearly every flight when a larger one will still meet the weight limit?

Thats my approach anyway!
Old 04-11-2010, 12:54 PM
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DagTheElder
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Default RE: Is 10c 5000mAh package to much?

Hi and thanks Chad,

Very interesting and good arguments to support a long longevity. I agree that the larger the capacity and the less you discharge the better longevity.
I am curious to know where the longevity crosses the capacity and discharge if one has power enough to fly a sequence. To walk on the edge so to speak.

Should LiPo's come with a discharge, cycles, aging curve ...........? for comparison of quality?

I do hope we have not seen the max energy density in LiPo packs.

Is there other opinions re this issue out there???????

Best regards
Old 04-11-2010, 02:05 PM
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joenella
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Default RE: Is 10c 5000mAh package to much?

Hi Dag

I use these Lipo, after testing for a full season with great results. I normally charge 2500-2600 mAh after 1 round Nordic and the voltage is showing almost 38V after the flight.
http://www.hobby4u.dk/index.php?page...emart&Itemid=2
I have more than 100 cycles on them and compared to new ones they lack max 5-8%

They are great and really lightweight.

brgds
joen
Old 04-12-2010, 03:50 AM
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DagTheElder
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Default RE: Is 10c 5000mAh package to much?

Thanks joenella!

Battry pack/ capacity duly noted.

Regards

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