LiPo End Voltage for max charge cycle for Turnigy Nano?

[mvly]

I have Turnigy nanotech 4.5Ah 37V battery in series to get 74V nominal. I read from this forum that the charge end voltage should 4.1V to get max charge cycle without compromising too much capacity. Is this true? What is the realistic capacity if I charge it to 4.15V? 4.13V? to 4.10V?

I am currently setting it to 4.13V end charge Voltage.

Thanks

 

[Floont]

The lower the high end charge voltage cut-off is, coupled with a higher low end cutoff, the longer the life your LiPo's will be. A high end cutoff of 4.10VDC is the accepted reasonable max charge limit by which you get a reasonably full charge and will have a long life expectancy.

Also, the higher the high-end cutoff, the more likely you'll have to balance more often.

I would stick with 4.10v.

 

[mvly]

Thanks for the reply. I balance my batteries everytime anyways. Can I squeeze some more Ah out if I set it to 4.13V if I balance charger everytime?

 

[Spacey]

I take mine to 4.1,v, one cell which is a bit buggered goes to 4.14v......I then discharge to about 3.75v. I should get a good amount of cycle from that?

 

[dogman dan]

My cheap chargers go to 4.2 so I've been charging to that. No lilo setting on mine. In general, once they had a few dozen cycles on them, they started self discharging back down to somewhere around 4.15- 4.17 anyway. So you pretty much won't lose anything by charging to only 4.15 in my opinion.

The easy way to find out the answer to your question would be to charge till 4.10. Then restart the charger, and finish. The charger will read out the miliamphours it put in, which would now be the difference between 4.10 and 4.20v. Then just divide that number by the number of cells in the pack if you want the per cell number. I don't think it's a very significant number of wh. And if that amount is going to make you hit lvc every ride, you already screwed up and made the pack too small.

 

[auraslip]

The lower the better, but quantitative wise who knows?

We do know that more cycle life reducing side reactions occur at higher voltages. You can read some studies on google scholar about capacity fade at different charge voltages, but how does that apply to lipo? Who knows. Especially when each type is made of a different formula.

4.10v-4.15v is often recommended not just because it's better for lifespan, but also because it offers protection from overcharging if a cell becomes out of balance (if you're bulk charging)

 

[ZOMGVTEK]

I bulk charge to 4.10, and balance charge to 4.12. The highest I want to see any cell is 4.15 after its been sitting. Charging to 4.2 is fine for RC use, but not worth it for e-bike use.

Keep the discharge about as shallow as you can. I would't use 10% capacity then top off, but try to keep discharges above 50-60% when possible. Never go below 3.5, try to stay above 3.65.

 

[mvly]

OK I did some test.

Here is my setup so people know:
6x --- 10s 37V 4.5Ah Turnigy nanotech
I hook them up in 2s3p to get 20s 74V 13.5Ah battery

Here is the test:
1) I balanced charger to 4.10V and ran it down 4.5Ah according to CA
2) I balance charge to 4.10V. The icharger showed around 4.55Ah or 4.60Ah inputted so it CA is calibrated pretty accurately
3) I ran the battery down 4.7Ah according to CA
4) I balance charge to 4.13V. The icharger now shows 5.1Ah inputted.

My conclusion:
It looks like end charge from 4.10V to 4.13V added around 0.3Ah counting discharging during balancing and errors.
For my ebike, which uses around 51Wh/mi on average (I go really fast. ), this will equate to around 0.43miles extra.
So I guess it really depends on what people want. 0.43 miles is not far, but it might mean the difference between pedaling home or light pedaling home.
As for me, I don't think it's worth it. I set LVC for my Lipo at 74V (3.7V per cell) so I use my bike for short distance anyways.
I will change my end charge V to 4.10V to increase my battery charge cycle

Hope this helps for others here.

 

[kfong]

What hasn't been mentioned is the time it takes to charge that last bit of energy is exponential.