wallstreet

iTrader: (24)

Rick can you fill us in on the equipment you used for balancing and charging?

I saw a photo of your pit and there were a few different things in there.. just wondering what worked the best. I need a charger and balancer.

syndr0me

iTrader: (32)

Rick,

Did you experiment at all with heating the cells while using them at the nats? Did you notice any disadvantage (or advantage) with the LiPo when running them against people using NiMH?

Rick Hohwart

When recharging, the battery would take about 3500 for modified and 2600 for 10.5.

I was testing a balance charger from a company we might deal on the electronics side of things. I think the same company makes Losi/Horizon's balance charger. It works very well although I did not use the balance charge fucntion as I did not have a balance port extension that would allow me to charge in the LiPo sack. So I used the standard LiPo charge function.

The LRP works well but I did not have a proper Deans plug adapter and was worried about shorting the battery.


I did not. I wanted to use the batteries in the simplest way possible. And in a way that most users will want to use them. I had two batteries per class. So what I did was charge each battery after I ran it and set it aside for use the following day. And repeated the process each day. For the main day, I had to run 6 times so I ran two batteries twice.

In modified, I was as fast as I felt comfortable. I could have been faster but with modified you can be too fast and go slow. So it is not the best test. In 10.5, you can use all the power you can get. And I felt I was as fast or faster than the other 10.5 cars in the A-main. My car was ultimately not as good (getting into the corner), as the others, but it was fast!

I have bench tested battery warming and multiple cyles with no real difference in performance. But i will have to do some track testing to see what i can come up with. For now, I don't think any special care or precedures are necessary.

syndr0me

iTrader: (32)

Thanks Rick, I appreciate the info.

I've been experimenting with getting LiPo (different brand) to around 130F before running them (after a charge), and the increase in voltage was significant enough that I thermaled my motor when using the same gearing as a cold pack. However, my understanding is that the benefit of heating packs may be highly dependent on cell chemistry, and could vary from one manufacturer to the next.

Running them the most simple way possible sounds like a big win. :-)

Thank you for testing these on such a large stage. It seems like pro racers are slow to try new things at big races, presumably because of sponsorship deals and such. It's great to get feedback like this, it doesn't seem to happen often enough.

overflow

iTrader: (8)

How much weight did you have to add? I also herd about a possible new chassis for the tc5 to better accommodate the lipo. Can you give any info on this?
Thanks for the info!

Rick Hohwart

130F seems awfully high. I guess it depends on the class you are racing but 100F seems to be the best starting point. But it will depend on each individual cell.

Rick Hohwart

It works out to about 5 ounces. A new chassis is not necessary and not planned at this time.

overflow

iTrader: (8)

Thanks again for the info, looking foward to picking one of these up!

Johnny Wishbone

iTrader: (6)

So Rick, since your about the only guy I know thats straight up about everything and you where running the LiPo at the Nats, did you have, or did you hear of anyone with battery issues, you know, fires, melt downs, explosions? This question is not only for LiPo but for NiMh as well, curious minds want to know. Thanks

Rick Hohwart

There were no LiPo issues. But most of the drivers used NiMH. ROAR was pretty good about requiring charging LiPos in a LiPo sack, and checking the battery voltage in tech. There is no way you could mess up a battery.

There were at least two NiMH battery failures although I did not witness them personally.

dodgeguy

iTrader: (208)

There were voltage issues on lipo's at tech. There were some chargers taking the voltage above the 8.44 spec. I do not htink Rick had this problem.

Verndog

iTrader: (16)

I have one of AE's top drivers testing our TC5 weight system with the new Reedy packs. I expect to have some feedback soon on how they worked out. He's mounting them with the base weight and side weight both that can be seen here. As seen that adds 5.5oz




In the testing I've done and feedback from others, likely I'd recommend removing the humps and installing the 3.0oz base plate...that is if they allow pack movement anything like the Orion 3600 humps. If not, great, but you loose the opportunity to help drop COG buy putting plastic in those slots instead of a heavier metal.

Another option is flip the packs "humps up" and mount to a mounting plate if you dont want to mod your pack. The wiring exit looks user friendly enough to give serveral options.

Dawn Sanchez

True.. this was found to be one charging system in particular. Using a different system on the same battery - the battery was found to be within legal limits on several post charge occasions.

I will be contacting this charging system supplier/MFG later this week to see what ROAR can do to assist our membership with this situation at future events.

Xpress

iTrader: (3)

Did you do any back to back testing between LiPo and NiMH at the race? Your thoughts?

Rick Hohwart

I have not found a single LiPo charger that when set at 8.40. volts produces a charged battery that reads 8.40V on a voltmeter. Even two chargers from the same manufacturer produced different ending voltages.

The problem is that the components used can easily produce readings that can easily vary up to .04V. With NiMh this is not an issue because the actual voltage is insignificant. We are measuring the changes in voltage.

ROAR will not be able to require manufactueres of chargers to use higher priced componenets that minimze voltage variations. The only thing they (or any track) can do is check the voltage of each car as it passes through tech.

I did not. For me, the object of this test was to always run LiPo so that I could determine the proper gearing, ESC settings, and car setup without influence from NiMH settings.