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LiFe or NiMH rx battery
05-06-2011, 07:50 PM
#27
RE: LiFe or NiMH rx battery
I thought the "holes" description only applied to p-type semiconductors.
How else would you have sparks or lightning?
The electrons in metal move randomly until they experience a difference in electrical potential; and then flow.
How else would you have sparks or lightning?
The electrons in metal move randomly until they experience a difference in electrical potential; and then flow.
05-07-2011, 12:13 AM
#28
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RE: LiFe or NiMH rx battery
I have 2 LiFe packs (one 3200mAh and the other 1300mAh). Bought the first one on CGR's recommendation along with a GP Triton2EQ charger. Then I bought the other one becuase of problem with the first.
When I tried to charge the 3200mAh on the Triton2EQ, charger refused to even accept the battery if it was fully charged. I discovered later that this may be because the setpoint for the charger is 6.6v whereas the fully charged voltage for LiFe is nearly 7.2v with no load (it drops to 6.6 when loaded, hence no regulator is required for RX applications). This is probably a quirk of this specific charger. Later I got Hobbico's own LiFe charger along with the 1300mAh and it charges both the batteries easily.
Like CGR, I vouch for the capability of these to retain charge. The 3200mAh was out of use for one and half month and when I took it out to charge (just to be sure) in January, it immediately beeped peak charge. Doubting it, I put it on the Triton2EQ's NiCd discharge cycle and it delivered the full 3200mAh!
Another advantage is regarding the weight of the battery. My 3200mAh is definately heavier than my 2000mAh hydrimax NiMH pack but the 1300mAh LiFe is much lighet and much smaller- its about 75g lighter and about the size of a pack of playing cards.
I am aware of the sharp drop at the end of discharge in the LiFe. But reality is that for RX applications we really dont use anywhere near the maximum capacity of even the NiMh battery- even after 5 flights we may have used 300-400mAh. But I am sure the LiFes will help when I install them on the DLE20/30 ignition where their capacity will be really used.
In conculsion of the "battery experiment" this last flying season, if my LiFes had worked in the first go without charger problems, I would have never bought the NiMH
Ameyam
When I tried to charge the 3200mAh on the Triton2EQ, charger refused to even accept the battery if it was fully charged. I discovered later that this may be because the setpoint for the charger is 6.6v whereas the fully charged voltage for LiFe is nearly 7.2v with no load (it drops to 6.6 when loaded, hence no regulator is required for RX applications). This is probably a quirk of this specific charger. Later I got Hobbico's own LiFe charger along with the 1300mAh and it charges both the batteries easily.
Like CGR, I vouch for the capability of these to retain charge. The 3200mAh was out of use for one and half month and when I took it out to charge (just to be sure) in January, it immediately beeped peak charge. Doubting it, I put it on the Triton2EQ's NiCd discharge cycle and it delivered the full 3200mAh!
Another advantage is regarding the weight of the battery. My 3200mAh is definately heavier than my 2000mAh hydrimax NiMH pack but the 1300mAh LiFe is much lighet and much smaller- its about 75g lighter and about the size of a pack of playing cards.
I am aware of the sharp drop at the end of discharge in the LiFe. But reality is that for RX applications we really dont use anywhere near the maximum capacity of even the NiMh battery- even after 5 flights we may have used 300-400mAh. But I am sure the LiFes will help when I install them on the DLE20/30 ignition where their capacity will be really used.
In conculsion of the "battery experiment" this last flying season, if my LiFes had worked in the first go without charger problems, I would have never bought the NiMH
Ameyam
05-07-2011, 03:21 AM
#30
RE: LiFe or NiMH rx battery
Ameyam: There was a discussion about a year or so ago about LiFe packs and the discharge curve as it differs from LiPo, NiMh, and NiCd packs. The issue was about using Voltwatch 2 with them and the charge remaining when the LED's are still green.
The curve is very flat until only a few moments before it falls off to almost nothing. The point was that they are great for our purposes, lighter than the equal pack of the same capacity and prvide a good surge current when needed. And, ounce for ounce, the duration of LiFe packs are better. What that means is that no matter.. if it's an 1800 mah pack, well, that's the capacity and you get the same approximate duration with one as you would with any other chemestry of the same capacity. The advantage is the weight difference, where needed, you will get a lighter battery pack with the LiFe as compared to it's equal capacity pack of other chemestry.
Note, I said approximate duration. Some minor differences, such as the flatter discharge curve that allows more current at the same voltage as others would.
It comes down to a choice: do you want to higher capacity with less weight or doesn't that matter.. the expense of LiFe packs, requiring a charger that is compatible with that pack may not be of your liking.... or it may. Depending, again, on your choices.
CGr.
The curve is very flat until only a few moments before it falls off to almost nothing. The point was that they are great for our purposes, lighter than the equal pack of the same capacity and prvide a good surge current when needed. And, ounce for ounce, the duration of LiFe packs are better. What that means is that no matter.. if it's an 1800 mah pack, well, that's the capacity and you get the same approximate duration with one as you would with any other chemestry of the same capacity. The advantage is the weight difference, where needed, you will get a lighter battery pack with the LiFe as compared to it's equal capacity pack of other chemestry.
Note, I said approximate duration. Some minor differences, such as the flatter discharge curve that allows more current at the same voltage as others would.
It comes down to a choice: do you want to higher capacity with less weight or doesn't that matter.. the expense of LiFe packs, requiring a charger that is compatible with that pack may not be of your liking.... or it may. Depending, again, on your choices.
CGr.
05-07-2011, 01:16 PM
#31
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RE: LiFe or NiMH rx battery
ORIGINAL: CGRetired
There is a law of physics that states that matter cannot neither be created nor destroyed. If you have a certain number of free electrons that flow from one point to another, no matter what the chemestry is, that is the number of free electrons that will flow.
The energy behind those electrons is going to differ from one material to another.
And the construction of a battery pack will make differences in internal resistance that will either add or subtract from the active flow from one pole to another.
2000 mah is 2000 mah.
Ohm's law states that for a specific voltate and resistance, a specific amount of current will flow. And, for a specific amount of amperage and voltage, the watts consumed a factor of the voltage and current.
Components will vary the load, which will not change the chemestry, but will change the amount of current drawn by the load.
These laws of physics are pretty constant on this planet. There are a lot of internal factors in batteries that change such things as internal resistance and the delivery energry of the free electrons, but not of the electrons themselves. The forces in action vary from one type of battery pack to another, but the end result is the same. 2000 mah is 2000 mah.
CGr.
There is a law of physics that states that matter cannot neither be created nor destroyed. If you have a certain number of free electrons that flow from one point to another, no matter what the chemestry is, that is the number of free electrons that will flow.
The energy behind those electrons is going to differ from one material to another.
And the construction of a battery pack will make differences in internal resistance that will either add or subtract from the active flow from one pole to another.
2000 mah is 2000 mah.
Ohm's law states that for a specific voltate and resistance, a specific amount of current will flow. And, for a specific amount of amperage and voltage, the watts consumed a factor of the voltage and current.
Components will vary the load, which will not change the chemestry, but will change the amount of current drawn by the load.
These laws of physics are pretty constant on this planet. There are a lot of internal factors in batteries that change such things as internal resistance and the delivery energry of the free electrons, but not of the electrons themselves. The forces in action vary from one type of battery pack to another, but the end result is the same. 2000 mah is 2000 mah.
CGr.
its the internal resistance of the batteries which causes them to "heatup" and loose some of their mah to heat and resistance. nimh batteries have a much higher internal resistance than life batteries so the life batteries will last longer if you have a high load on them.
if you dont agree with my results feel free to prove my wrong with actual tests, wouldnt be the first time i have been wrong and wont be the last, just with the equiptment i have and the testing i have done life batteries last longer than nimh batteries of the same mah under significant loads , if anyone really wants some graphs let me know and ill go run and do the tests again, shouldnt take long.
05-08-2011, 12:55 AM
#33
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RE: LiFe or NiMH rx battery
ORIGINAL: CGRetired
Ameyam: There was a discussion about a year or so ago about LiFe packs and the discharge curve as it differs from LiPo, NiMh, and NiCd packs. The issue was about using Voltwatch 2 with them and the charge remaining when the LED's are still green.
The curve is very flat until only a few moments before it falls off to almost nothing. The point was that they are great for our purposes, lighter than the equal pack of the same capacity and prvide a good surge current when needed. And, ounce for ounce, the duration of LiFe packs are better. What that means is that no matter.. if it's an 1800 mah pack, well, that's the capacity and you get the same approximate duration with one as you would with any other chemestry of the same capacity. The advantage is the weight difference, where needed, you will get a lighter battery pack with the LiFe as compared to it's equal capacity pack of other chemestry.
Note, I said approximate duration. Some minor differences, such as the flatter discharge curve that allows more current at the same voltage as others would.
It comes down to a choice: do you want to higher capacity with less weight or doesn't that matter.. the expense of LiFe packs, requiring a charger that is compatible with that pack may not be of your liking.... or it may. Depending, again, on your choices.
CGr.
Ameyam: There was a discussion about a year or so ago about LiFe packs and the discharge curve as it differs from LiPo, NiMh, and NiCd packs. The issue was about using Voltwatch 2 with them and the charge remaining when the LED's are still green.
The curve is very flat until only a few moments before it falls off to almost nothing. The point was that they are great for our purposes, lighter than the equal pack of the same capacity and prvide a good surge current when needed. And, ounce for ounce, the duration of LiFe packs are better. What that means is that no matter.. if it's an 1800 mah pack, well, that's the capacity and you get the same approximate duration with one as you would with any other chemestry of the same capacity. The advantage is the weight difference, where needed, you will get a lighter battery pack with the LiFe as compared to it's equal capacity pack of other chemestry.
Note, I said approximate duration. Some minor differences, such as the flatter discharge curve that allows more current at the same voltage as others would.
It comes down to a choice: do you want to higher capacity with less weight or doesn't that matter.. the expense of LiFe packs, requiring a charger that is compatible with that pack may not be of your liking.... or it may. Depending, again, on your choices.
CGr.
][]?Ameyam
