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Aug 08, 2020, 07:14 PM
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Fallguy44's Avatar
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Discussion

6.6v LiFE receiver battery with 6v servo


For a servo rated for 4.8v to 6v can a life battery be used?
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Aug 08, 2020, 08:52 PM
Registered User
Yes. The servo will be faster draining the batteries faster too.

Tai
Aug 08, 2020, 09:17 PM
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Fallguy44's Avatar
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Quote:
Originally Posted by tai626
Yes. The servo will be faster draining the batteries faster too.

Tai
Hmm. Interesting. Thank you
Aug 09, 2020, 10:56 PM
Retired Electronics Specialist
vollrathd's Avatar

Life or A123 usage


FYI

These A123's or IMHO, the lower quality LiFe batteries configured with two cells for a receiver battery pack are a near perfect source for receiver and servo power in our larger RC models. Near perfect that is.

Their main drawback is their very flat discharge voltage curve during a day of flying. That indicates that a simple voltage check will not provide any indication of how many more flights can be made before total discharge of the battery pack.

What works very well is the PDF file I created awhile back on the proper use of these battery chemistries.
Last edited by vollrathd; Aug 10, 2020 at 01:32 AM.
Aug 10, 2020, 12:46 AM
20 bucks is 20 bucks
zippybatts's Avatar
Those 2500mah A123 are rather large Vollrathrd, LiFE are much smaller and fit a broader range of models. A123 or the round ones are good in large models but not with 7.4V servos, for smaller models if 6V servos are used LiFE are near perfect. I do not have any servos limited to 6V so I do not use A123 or LiFE.
Aug 10, 2020, 01:37 AM
Retired Electronics Specialist
vollrathd's Avatar
Quote:
Originally Posted by zippybatts
Those 2500mah A123 are rather large Vollrathrd, LiFE are much smaller and fit a broader range of models. A123 or the round ones are good in large models but not with 7.4V servos, for smaller models if 6V servos are used LiFE are near perfect. I do not have any servos limited to 6V so I do not use A123 or LiFE.
Yeah
I missed the word "larger" models. I've found a half dozen LiFe receiver packs in my RC club in the past few years with a low capacity cell. That's 60% or less capacity on one cell.

IMHO, it would be wise to cycle test those LiFe packs once a year or so with a high quality battery analyzer.

For me, I use my West Mountain CBA battery analyzer.
Aug 10, 2020, 07:40 AM
Registered User
A123 also has 1100 mah cells that have worked well for me.
Aug 10, 2020, 11:22 AM
Retired Electronics Specialist
vollrathd's Avatar
Quote:
Originally Posted by Al M
A123 also has 1100 mah cells that have worked well for me.
Good point, these would be great for the smaller models. I have two of those cells for any future projects.

One of my RC club mates asked me to checkout his two cell 1100 mag A123 pack that he had run down to 0.1 Volts per cell.

I got the two cells to 3.1 Volts, then finished the charge cycle. Then ran two cycles on my West Mountain CBA battery analyzer. And got 1050 mah both times. Typical result.

Try that wit a LiPo!
Last edited by vollrathd; Aug 10, 2020 at 11:27 AM.
Aug 10, 2020, 11:50 AM
Registered User
I do that 1 time a month with my Black & Decker 4 cell 1100 s. For YEARS. still good at 93 ish capacity. No heating or fire risk. The charger requires 2 resets to finish a balanced charge.
Aug 12, 2020, 04:20 AM
Proud to eat Kraut ;-)
Julez's Avatar
Quote:
Originally Posted by tai626
Yes. The servo will be faster draining the batteries faster too.

Tai
Not, it will actually drain the batteries slower, as less current is needed to deliver the same power output when the voltage is at a higher level.
Servos are not an ohmic load.
Aug 12, 2020, 04:27 AM
20 bucks is 20 bucks
zippybatts's Avatar
Quote:
Originally Posted by vollrathd
Good point, these would be great for the smaller models. I have two of those cells for any future projects.

One of my RC club mates asked me to checkout his two cell 1100 mag A123 pack that he had run down to 0.1 Volts per cell.

I got the two cells to 3.1 Volts, then finished the charge cycle. Then ran two cycles on my West Mountain CBA battery analyzer. And got 1050 mah both times. Typical result.

Try that wit a LiPo!
I would throw that battery myself, 1100 is not a lot of capacity.

Have you tried Lithium Iron, they have better capacity and voltage then A123 and still have reliability and safety?
Aug 12, 2020, 09:12 AM
Frankenstein recycled packs
rampman's Avatar
Quote:
Originally Posted by zippybatts
I would throw that battery myself, 1100 is not a lot of capacity...
Most of my .40 size and larger planes only use between 50mAh and 80mAh. The 1100 cells are closer to 900 so with that said I can fly at least 5 flights before I need to worry about charging my RX pack again.

Rick
Aug 12, 2020, 11:23 AM
Retired Electronics Specialist
vollrathd's Avatar
Quote:
Originally Posted by zippybatts
.

Have you tried Lithium Iron, they have better capacity and voltage then A123 and still have reliability and safety?
Are you referring to Lithium Ion? Or Lithium Iron Phosphate? The LiFe and A123's use the latter chemistry.

I'm not a fan of the plastic baggies used on the LiE'sthough, having found six of them withonecellhainglowah capacity
Aug 12, 2020, 11:24 AM
Retired Electronics Specialist
vollrathd's Avatar
Quote:
Originally Posted by zippybatts
.

Have you tried Lithium Iron, they have better capacity and voltage then A123 and still have reliability and safety?
Are you referring to Lithium Ion? Or Lithium Iron Phosphate? The LiFe and A123's use the latter chemistry.

I'm not a fan of the plastic baggies used on the LiFe's though, having found six of them with one cell having low mah capacity.

As a comparison, A123's use a hermetically sealed aluminum case.
Aug 12, 2020, 12:37 PM
Registered User
Quote:
Originally Posted by Julez
Not, it will actually drain the batteries slower, as less current is needed to deliver the same power output when the voltage is at a higher level.
Servos are not an ohmic load.
And I stand corrected.

About 10 years ago, I was comparing the 4.8V NiCd and 6.6V LiFe in the same configuration 6 servos+receiver for 2+hrs intermittently flights of 10min each. The 6.6V batteries depleted faster than 4.8V. But since I could fully charge LiFe between flight, I havenít bother to check again. Maybe 6V digital servos today are different than the old 4.8V analog servos we had.

The final answer is still YES :-)

Tai


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