Battery runtime/quality?

Ozric

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Both of these batteries are pretty new. Bought the Lectron with the Mojave a few weeks ago and the Spektrum a week later. Both have had maybe 4 runs on them and both have only been balance charged and storage charged when done. The Lectron gets me 1/3 or 1/2 the runtime that the Spektrum does. Is this just “you get what you pay for”, or could there be something wrong with the Lectron?

8E7C1BA6-B83C-4482-838D-176AF17265BD.jpeg
 

Ozric

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If your charger has the feature, get a reading of the internal resistance (IR) of the cells and report back. If one of them is way out that might be the reason.
Not sure if my charger can do that but may pick up a Cel checker. Is this something that can be fixed?
 

Ozric

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Unfortunately not. Well, not unless you have another battery of the same kind to transplant a cell from, no.
Ok thanks. I’ll bring it in to HobbyTown and show them. Maybe they can check is themselves and work with me since I just bought it.
 

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It should not be that much different. Like said above more than likely you are experiencing lipo sag with the lectron. This means that under load a cell or cells pull down under the lipo cutoff on the esc. If this is the case turn the car off and let it sit for like 30 seconds. This should give the battery time to recover and see if it drives again at 100%. If the esc has a lower LVC (low volt cutoff) setting you could add runtime by lowering the value. This would result in higher runtime for both batteries.
 

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I noticed that with some budget brand batteries, the discharge curve is clearly optimized for much lower current draw, and when used with higher current R/C loads, they wind up cutting off long before all their available energy has been expended. I suspect this might be what you're encountering. Chart below made from tests I did comparing one Zeee (good) to another Zeee (bad) and a Spektrum (good). LVC kicks in at 3.2V/cell, which when adjusted for voltage sag is about 3.6V/cell on the chart. You can see that the battery represented by the red line can only supply 3000-3500mAh of its 6000mAh capacity.

lipo_voltage_mah_discharge.png
 

Ozric

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I noticed that with some budget brand batteries, the discharge curve is clearly optimized for much lower current draw, and when used with higher current R/C loads, they wind up cutting off long before all their available energy has been expended. I suspect this might be what you're encountering. Chart below made from tests I did comparing one Zeee (good) to another Zeee (bad) and a Spektrum (good). LVC kicks in at 3.2V/cell, which when adjusted for voltage sag is about 3.6V/cell on the chart. You can see that the battery represented by the red line can only supply 3000-3500mAh of its 6000mAh capacity.

View attachment 256967
Ah, thank you. Would this explain why when I go to storage charge it, it says full?
 

Ozric

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So I went to my local HT and they put the battery on a cel checker (after I gave it a full charge) and it looked fine. Got home and my charger timed out trying to storage charge it. I've ordered a cel checker but currently do not know where each cel is at. I'm really confused about this battery.
 

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So I went to my local HT and they put the battery on a cel checker (after I gave it a full charge) and it looked fine. Got home and my charger timed out trying to storage charge it. I've ordered a cel checker but currently do not know where each cel is at. I'm really confused about this battery.
Well, to be fair, storage charging a pack from full charge on a charger is going to take forever. Discharge rates of most chargers is really low, like in the 0.5A range. It would be a lot faster to drain it by driving the car around and then storage charging it.
 

Ozric

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Well, to be fair, storage charging a pack from full charge on a charger is going to take forever. Discharge rates of most chargers is really low, like in the 0.5A range. It would be a lot faster to drain it by driving the car around and then storage charging it.
Ah. Thank you. I’ve still got lots to learn.
 
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