Yes, agreed. so i decide to play happily first as long as the packs provide reasonable play times. Thanks Ching. Hope to meet you sometimes in JV. Still learning and trying different settings as the car(DF02 but playing on-road) is not designed for on-road. Changed all the original plastic turnbuckles and steering tod to adjustable ones. It looks much better and seems to go straighter. Please bear with me if you see a "new hand" playing terribly with a DF02 in JV.
Sometimes the more information our chargers give us, the more worried we appear. As long as you can bash happily with the Li-Po packs, don't bother too much with all the figures. 8.31V is not bad after all.
Thanks for your comment. I just returned back to RC world after 8 years.
I did an experiment and probably it is the battery problem.
I have 2 new lipo chargers - one AC/DC max 6A and the other 20A - both bought within one month. I have 2 new 4200mAH 40C lipo packs bought within one month as well. After storage, both packs can only be fed with less than 2000mAH with balance charge. Previously I used the 20A one and the final vlotage was 8.31V after a while from completing the charge. I just balance charged the 2 packs this afternoon with the 6A one and they both showed ~8.31 - 8.32V after a while from completion. Both chargers gave out the similar(but not 8.4V) final voltage after full charge. I set 4.8A to charge in both chargers. What a disappoinment? Maybe the chargers and the lipo packs are all bad....
If your packs are new, they shouldn't drop from 8.4V to 8.31V within a short period. My guess would be you charger may not have really fully charged the pack. The 8.4V may include the real internal voltage (8.31V) and the voltage drop (0.09V) across the cells due to the final charging current. Once you have disconnected the charger, the charging current is interrupted and the 0.09V vanishes.
A good charger should have a very very small final charging current so the 8.4V can be fully "plugged" into the pack.
Either your charger or your voltmeter is not accurate. Did you measure the voltage after the char ...
Allan Hing,
I did both - while charging and immediately after the charger shows full. I also measured it both while it was connected to charger and then disconnected from the charger right after the charge completed - both readings from the voltmeter read 8.31V. The charger is new too, bought in less than one week. The lipo pack was played for 2 times only and each time it discharged(started at ~ 7.89v) when doing storage after playing so difinitely it was not over discharged in playing.
I am pretty sure the voltmeter is quite accurate as I have a power supply which reads 13.8V on its display and the voltmeter shows 13.8V too.
Ching,
After balance charge, my 2S new lipo gets 8.31v only? Charger shows 8.4V but voltmeter shows ...
Either your charger or your voltmeter is not accurate. Did you measure the voltage after the charging was completed or while the pack was still connected to the charger?
Ching,
After balance charge, my 2S new lipo gets 8.31v only? Charger shows 8.4V but voltmeter shows 8.31V. I check the individual cells, they add up to 8.31V also. Is that normal? Tks.