LiPo performance

[Chequered Flag Racing]

Raced @ Worksop recently with TP32 saddles in 2wd drive.

Charged them the day before event.

Ran a practice round and 1st heat on 1 pack. Used my second pack without top up for 2nd round.

Recharged pack 1 for R3 and the performance, get up and go, was so much better. Ended up just topping p1 up for the rest of the day

Anyone else finding better to charge their LiPo on the day like NiMh?

[super__dan]

The 20C TP3200's I have previously tried whilst not bad, I'm sure TP would admit they have newer and better cells now. From the various ones I've tried, when you get up to the larger C larger capactiy Lipos the difference is much less noticable, they are very consistent (assuming you only talk about off road).

[COFFIN DODGER]

Glen , Quite a few of us at our club who use 3200 Trakpowers have noticed exactly the same thing as you. We now only charge on the day, same as nimhs.

[Col]

the 4900 sticks don't suffer from this problem. Mine were charged 4 days ago and run superbly tonight

[ianjoyner]

Originally Posted by Chequered Flag Racing

Raced @ Worksop recently with TP32 saddles in 2wd drive.

Charged them the day before event.

Ran a practice round and 1st heat on 1 pack. Used my second pack without top up for 2nd round.

Recharged pack 1 for R3 and the performance, get up and go, was so much better. Ended up just topping p1 up for the rest of the day

Anyone else finding better to charge their LiPo on the day like NiMh?

Could it have been the temperature difference between the packs? I'm not sure if charging on the day makes a difference, but certainly the difference between a warm and cool pack is very noticeable.

[Cockerill]

I agree with Glenn on this one. I find a noticeable difference if the battery is charged on the day or a couple of days previous. It's been the same with any lipo I've tried.

[Chequered Flag Racing]

Originally Posted by ianjoyner

Could it have been the temperature difference between the packs? I'm not sure if charging on the day makes a difference, but certainly the difference between a warm and cool pack is very noticeable.

Should have included this in the 1st post.

The LiPo were straight from overnight in garage to car boot, 2 hour journey to venue so would have been @ near ambient temp and into the hall. Installed in car and used. So after 1st two runs I would guess they would be at a decent working temp all day as I used only one pack.

Ran a single pack all day yesterday @ Batley on a 7.5bl geared 26/78 for a a B4 gearbox putting in cira 1200mah after a run. We had 8 heats so cells were used in a race, rested for 6 or 7 mins whilst marshalling then back on charge.

I have a pack that I charged for Worksop that I will try and get graphed via a Pro-Trak to see how a precharged pack perfrom over a warmed pack. I'll use the same pack for the testing using an 8 heat simulation. Back tonight with data hopefully.

[Lee]

I mentioned this months ago about lipo and got shot down by people saying it was in my head.
It's good to see that fellow racers and Xfactory brother Multiple european A finalist Thomas Cockerill are finding the same things

[Chequered Flag Racing]

Originally Posted by Chequered Flag Racing

I have a pack that I charged for Worksop that I will try and get graphed via a Pro-Trak to see how a precharged pack perfrom over a warmed pack. I'll use the same pack for the testing using an 8 heat simulation. Back tonight with data hopefully.

I still have it , that's a Pro-Trak and the skills to use it.

Testing 1 pack I used yesterday before I simulate an 8 heat event on the Worhsop pack.

[Chequered Flag Racing]

OK here's the data

Pack 4 was left for 2 weeks @ full charge for 2 weeks since Worksop

checked charged and it drew something like 0.5 amps for 30secs or so before tripping out.

graph shows line colour and time of discharge to the right

1st pic is just the cell volts over 3 discharges
2nd pic shows individual cell volts over 3 discharges

pack was charged @ 3.2a to 8.4v and discharged to 3v per cell as Pro-Trak will allow this using a cell cut off of 3v

pack was balance charged between each discharge.

PT graphing software tripped on discharge 3 and had to restart discharge hence the slightly shorter run time. Volts seem to be OK for second & third discharge though for most of the graph

09:47:14 D/CAP TIME SPREAD PV1
PACK 4 3500 420 3 6.61
CELL1/ 0 3475 417 3 3.29
CELL2/ 0 3500 420 0 3.32

11:41:55 D/CAP TIME SPREAD PV1
PACK#00 3600 432 5 6.64
CELL1/ 0 3566 427 5 3.31
CELL2/ 0 3600 432 0 3.33

13:49:04 D/CAP TIME SPREAD PV1
PACK#00 3533 423 1 6.63
CELL1/ 0 3516 421 0 3.3
CELL2/ 0 3508 420 1 3.33

[ianjoyner]

Thanks for posting the results. Clearly something going on there. If you still have time on your hands?! Be interesting to see a repeat, but keep the pack in your pocket for an hour or so before the first discharge to get it nice and warm and see if there's still such a difference.

Also be interesting to see a comparison between a pack that's been sitting for a week fully charged vs a pack which has been sitting part charged, so the part charged one needs topping up before the first discharge. Would the one that's just been topped up show better performance than the one that's been sitting charged?

[Chequered Flag Racing]

Originally Posted by ianjoyner

Thanks for posting the results. Clearly something going on there. If you still have time on your hands?! Be interesting to see a repeat, but keep the pack in your pocket for an hour or so before the first discharge to get it nice and warm and see if there's still such a difference.

Also be interesting to see a comparison between a pack that's been sitting for a week fully charged vs a pack which has been sitting part charged, so the part charged one needs topping up before the first discharge. Would the one that's just been topped up show better performance than the one that's been sitting charged?

I'll have a go but it'll be a week or so before I get round to it. Got to do a bit of work some time you know.

I'll use the same pack 4 again

Have a part discharged pack in car that I'll use as the other test pack