John Stranahan

iTrader: (27)

There is some new LiPo battery info on the previous page.

Adam. Make sure you read around that last smiley face. I added some text.


My connectors are Deans. The Dean connector is not hot at all. The pack connectors under the shrink is what gets hot. I have kept the battery wires to the stock 14 gauge to choke off some amp draw. The Deans connectors hold up fine. They are very low resistance. After only a little use they are much superior to bullet connectors as the bullet always shrinks. The Dean spring is made of a good spring material and does not carry much current so it does not loose its tension with use.

140 F is what they are to finish the race with the 3.5R. It is hot in Houston. My NiMH would come off the track at the same temperature in the summer.
Average amp draws are in the 38 amp region during a race with the pan car and medium traction. No way not to deep discharge the pack and keep the speed up.

John

adamge

iTrader: (1)

Heh, unfortunately for you, I've already tested the 1010C! The attached pic shows my charging station at the peak of my flying (last year). I can get you a good deal on one, though, and it can ship with the battery if that hasn't already left.

And yes, I did need the second 750W power supply, AND the room fan to keep the chargers cool, as I was running them above-spec through an exploit. The packs were series-pairs of TP 5s3p6000.

syndr0me

iTrader: (32)

WOW! Man, you don't mess around. That's more intense than anything I've seen from the competitive racing crowd.

It's becoming apparent that LiPo is indeed going to have its own problems once it gains traction in competitive racing. Although I think the affect of cycle life on voltage and IR is going to come into play more than capacity, at least with the racing crowd. John, do you see a drop in voltage with increased cycles as well as capacity?

John Stranahan

iTrader: (27)

Dave- Well I'm still in awe wonderment and maybe a state of shock. Only one question. What is the gizmo between the power supply and the chargers. Is that what you overdrive them with.

Syndrome-The drop in voltage at a high load is my main concern with high drain usage, but as you can see by Mathijs and my previous race report that dumping is also concern with the 3.5 (less so with a 4.5). When I got new packs the difference in on track performance between the new and the old batteries (after 60 or so cycles) would definitely be a few places in a close field of racers. I am told that some brands (Kokam and Entertech) are able to produce batts that hold up better, I just am not able to buy any of these from sources advertized in the RC magazines. I have tried the Orion (Kokam) and it was weak from the start. I am not able to try dozens of packs from any one manufacturer though.

I note that that whole page of specs on the Thunderpower battery does little to inform you what the volage will be like after 50 high drain cycles. I have records on this on the few brands I am able to test.

syndr0me

iTrader: (32)

You touched on this before, but the concerning thing is that it seems as though the voltage of LiPo packs can be increased by sacrificing cycle life and safety, which was backed up by some things linger mentioned a while back. A weaker cell wouldn't be a huge issue if everybody was using them, and is certainly worth tolerating if it improves the safety and longevity of the battery. But, as it goes with racing, winning is king, at any nearly any expense. This is going to trouble LiPo's future in racing, especially without rules in place to prevent people from using and selling volatile, dangerous cells to gain and edge.

I realize this doesn't affect your situation directly, and won't be a big deal until LiPo starts getting acceptance in sanctioned racing, but it does provide a glimpse into the future, and I'm worried about what I see.

John Stranahan

iTrader: (27)

Ok here is some new data on the Thuderpower cells from Enerland. The Chemsitry is Lithium Cobalt Dioxide with some additives. Performance wise this chemistry has been the best for me previously with the Scorpion Cell from KoKam.

Now about the safety. I am quite concerned about the battery safety myself and have plenty of little stories about it on this thread and on my previous thread whose link is in the introduction. I bought Apogee Magnum Cells which were Lithium Manganeese and advertised to be safer (like the Orion cells are advertized to be safer). Well one time the Astroflight charger read an 80% charged cell as a 3s1p instead of a 2s1p at 80%. (No lectures please; see those earlier in the thread) In less than a minute the cell was puffed up huge. Graphite strap and chassis bowed to the max. We got the batt out covered it with a towel and lanced it. There was a small loud mushroom cloud type explosion and fire. People came by from 200 yards away to see. Now for me, three packs have been ruined in a meltdown or fire over 1 hard year of use. 12-16 runs a week. It always happens after an "incident" that I know about immediately. One reverse polarity. One internal charger misread. The last one a bearing seized and caused a meltdown (no fire, but almost).

My point is that even the safe ones cause fires after an "incident" so why not use the fast ones with good lifetime and try your best to avoid incidents. The orion cells are extremely easy to hookup backwards. This immediately ruins the cell. If you or the charger screws up, you know it. Then deal with the bad cell and dispose of it or quarantine it in a safe non flamable place for at least 24 hours. The Gas grill is a nice place to quarantine packs. Then try a better charger. So far my FMA balancing charger that is still for sale at FMA direct has been flawless. I have never had a problem with a crash damaging the cell and then causing a fire. I do use the soft sided cells exclusively, but I do protect them from puncture hazards in the car and usualy use a soft foam on the sides. So far storage or use without an incident there has been no hazard. Hell the Nitro guys run around with a gallon of Nitromethane enriched fuel in the trunk.

I would not buy another Astroflight deluxe LiPoly charger because of the one misread.

Pic is of my car with the new front suspension. We have not had a pic of the back of the car in a while.
John

Toughbeard

iTrader: (2)

John,

What is the stuff on the left and right side of the chassis. That thing looks, well, different

John Stranahan

iTrader: (27)

That stuff on my Prototype is 1/4 inch G10, a fiberglass phenolic laminate as is the lower pod plate on this car. On the left side it has three uses. Most important is that it extends the chassis to the rear and supports the left side of the rear Panhard bar. The Panhard bar locates the pod left and right. The G10 stiffens the chassis for the left lower link of the 3-link suspension. And it makes a side support when I run two LiPo packs in a touching saddle pack arrangement. There are other pics & closups earlier in the thread.

John

Toughbeard

iTrader: (2)

that thing looks mean

adamge

iTrader: (1)

I'm not sure what you are referring to. I was overdriving the chargers through a software trick. Set at 10s, the charger will only allow rate to increase up to 5A. But, set at 5s, the charger allows setting up to 10A. So, I would set it at 5s@10A, then increase the cell count, and it wouldn't decrease the current. That allowed me to enter a charge rate of 10s@6A, and the charger would do it (or overheat trying). Thunder Power fixed this bug in the firmware, though.
-Adam

Toughbeard

iTrader: (2)

he means the black box next to the 4 purple ones which are connect to the black one that is next to the purple ones...

Drewdc90

iTrader: (3)

Hey guys, i picked up an old RC10 the other day and ran it today. I was very surprised with the performance of it considering its age. I ran a novak 4.5 sensorless with the GM 95. I ran a 90/15 and the motor and speedie came in luke warm.
Drew.

adamge

iTrader: (1)

Man, that doesn't help me at all. Nothing in the picture is purple! Check your monitor settings ;>

There are four red chargers and one dark blue charger. There are two silver power supplies. There are four silver lipo balancers and four big black lipo packs. There is one black Sharpie marker, and one Micro Deans charge cable. The only thing remaining is the left rear speaker for my 5.1 home theatre system. It's not involved in the charging process - it just needed a place to sit.

John Stranahan

iTrader: (27)

Adam-The question is answered. That is just another dark blue charger. I thought the power supplies fed your system from the left just off the picture. But they must connect between the dark blue charger and the red chargers.

DrewDC90-Good luck with your car. It looks like it might not be an Associated car at all as it has Trinity on the Chassis. Maybe a Trinity Switchblade. Interesting front suspension, similar to a newly released car that Mathijs posted not to long ago.
John

elvo

Whoa! Inline axles!

The front of your chassis is starting to look like swiss cheese

Keep up the good work!