John Stranahan

iTrader: (27)

Note that there are pics and test data from a newly aquired Lithium Ion nanoPhosphate (Li nPO4) stick pack on the Previous page.

The 4000 mA-h Max Amp pack that dumped had 4040 mA-h onboard. This is down only a little from the as delivered 4238 mA-h. This ammount was sucked dry in 5:20 seconds (I took one practice lap). That gives the car a 44 amp average amp draw. It had some slipping problems toward the end so this may come down a little. The new 4700 mA-h batts should be sufficient for a strong finish.
I was surprised that the motor was only 160 F. The hottest point was upper inner. It was cooler down below. It would be much hotter in a JRXS. I expect the difference is much better radiant and convective cooling in the TC5 from having the motor very open to the air.
Further inspection of the car shows that the rear diff went south when the front diff melted down. This is a peculiar failure as it was working well.
The front pulley did not lock down on the quick repair as it had been worn thinner. I have new parts coming. I wish that steel outdrives/diff flanges were available now.
It would be nice if that TIR diff with the blue outdrive covers was available through their shopping cart.
John

yyhayyim

iTrader: (26)

That's my only concern w/ the TC5 now...parts! What is AE doing? What's teking them so long? They better hurry witht heir aluminum outdrives and a heavy duty spool. Hopefully its not a one piece spool, which will only break and damage the drive shafts and other components in crashes... The TIR spools are really good. I've used their delrin and Titanuim stuff they work nice and dont break, unless you ram hard into hard surface at really good speed.

About your motor temps....you got those 160F temps w/ your 7.4v Lipo or the 6.6V A123 pack?

John Stranahan

iTrader: (27)

I used 7.4 Volt 4000mA-h MaxAmp LiPos in the race as the only competition was 1/10 Nitro. Things are looking good from the speed control and motor. They may hold up to the heat.
The associated Spool will be a one piece unit. They have already available pin pillows. I have these in hand, which I assume will fit this one piece spool and possibly the Aluminum Outdrives. This should be available soon.
John

STLNLST

iTrader: (32)

both of those parts are out now. I'm a regular joe and I have them. Ordered straight from AE.

B4Bandit

iTrader: (10)

Hey John,

All I can say is that this is an amazing thread!

Thanks for all of your information, experience and testing. I drive a TC5, B4 and soon a B44, and am considering going to Lipo but am concerned about the fire hazard (although I'm always a little worried about my IB cells bursting too, after having one vent on my living room floor ).

You obviously think that they're safe enough don't you?

BTW, I PM'd you a link to some aluminium outdrives, if you haven't found some already. Only one left in stock... (about half way down the page)

Cheers mate,
Warwick.

John Stranahan

iTrader: (27)

Warwick-Thanks, and thanks for the post. I think the main danger for LiPo's is while charging. If you take some precautions while charging, then I think you are OK with them. I have found that dangers from a crash are not so high. Danger from just sitting in your bag are not so high. I plan to try them a while longer. I did notice that picture of the exploded NiMh that ripped through the graphite batterry strap. A lot of energy there. The LiPo burst is more of a soft burst of flame like you might get when lighting an aeresol can that is spraying a flamable liquid.
John

John Stranahan

iTrader: (27)

Scene of the Last Battery Fire
Here is a link to the pic of the scene of the crime during my last Max Amps Batterry fire. I just received it by e-mail. I put this here so that you will use more caution when charging these packs. I am continuing their use. The last pic was a very popular download with over 1100 hits.
John

yyhayyim

iTrader: (26)

John do you think that if it had happened w/ an Orion encased pack, it would have prevented the fire, or at least given you time to notice and remove the pack? How practical or safe is the encased Lipo pack, then?

John Stranahan

iTrader: (27)

I have little experience with the Orion packs. I have owned one but only for a short time. It was a tad slow in the car. They are supposed to be safer, but then so was the Lithium Manganeese pack by Apogee which burned quite well. The main purpose of the enclosure is to prevent denting of the corners and sides of the pack which could cause an internal short. I have had little problem in this regard, although I take steps to protect the pack sides, so I don't place much value in the hard sides.
When a pack expands it creates some pressure. The more you try and hold the pressure in with a case, the higher it will be before rupture. This will spray the solvent farther. That NiMH photo had a steel case. That's why the explosion was strong enough to break the graphite. The hard plastic sided packs afford little additional protection against charging mishaps in my opinion. The Orion(KoKam) internal chemistry does make for a smaller fire. I have seen lab test data on this. I just have not used these packs.

The new WorleyParsons packs I ordered are based on a KoKam patent. They may be very similar, for all I know, to the Orion Packs.
John

zake540

iTrader: (19)

John,

First of all, thank you for this outstanding thread. For a rookie onroad guy it has given me alot of valuable information.

Quick question on the Lipo failure you had. Can you tell me which charger were you using? What charge rate were you charging at? Also was it a balancing charger you were using? The reason I asked is because I've been flying electric airplanes and heli's for a while and I've been using a balancing charger and have yet to fired up a pack. Would it safe to say that a balancing charger is the safest route to go? My theory on why I don't charge without a balancing lipo charger is because if there is one bad cell the charger could keep pushing out amps to the good cell to achieve its overall peak 8.4v (2 cell lipo). I would bet that 99% of the time lipos catches fire is because overcharging.

John Stranahan

iTrader: (27)

Zake540-Thanks. Thanks for your post.

I agree with you that a balancing charger would be the best type. If a cell was weak the charger would shut off or try to balance forever. I also believe for car use that a charger that is permanently set to 2 cell would be the best type. There is no evidence a cell was weak here.

Here are the only facts available on this pack.
It had been tested and had 3000 mA-h of capacity a couple of months previously. It was charging normally back then and during maintenance.
It had been maintenacne charged part way every two weeks or so for two months. This was done mostly with a balancing charger.
The charger used for the final charge was not a balancing charger but was inspected to be on the proper charge sequence and had charged 1250 mA-h without incident on this pack. A peak was expected far into the future. 5 minutes later it blew.

From what I have read, I like the crystal growth theory. The battery shorted internally from the crystals that occur during high drain and which continue to grow with dissuse. It made some pops, a little smoke then a small fire then a big fire. It is common to store batteries during the off season. Maybe this is not soo good of an idea for "high Drain" LiPo packs. This pack was seeing 38 amp average amp draw for 5 minutes while in use.

The only conclusion is to charge the packs in a fire resistant area instead of in the airplane or car.

yyhayyim

iTrader: (26)

If its already bad due the growing crystalization within...then what will keep it from catching fire while running it on the car....lets say you store it fully charged and keep it stored for 2-3 months and then decide to use it again...you figure its got pretty much left to run 5 minutes so you just pop it in the car and go for a spin...and then....sssssssssss pufffff....could that happen?

John Stranahan

iTrader: (27)

I never had one die while running it in the car. I feel relatively safe from fire while storing it and running it because I have not heard of incidents, nor had any, in this part of its use. There are reports of after crash fires, so after a big crash (or an irregular incident) you should quarantine a LipO in a fireproof area for a day. I think the crystals in conjuction with charging caused the incident. This is just a loose hypothesis based on what I have read at the FMA web site.
John

yyhayyim

iTrader: (26)

Need your input:

for those who want to run Lipos- do you think its fair that if you want to run, say an Orion 4800mah pack, and your car weighs in at 1350g with that pack, and its 7.4v, of course....and you're racing against others who prefer the old 6 cell nimh packs, and they are running 6 cells at 1.3v each for a total of 7.8v, but their car weighs in at 1550g, due to the extra nimh pack weight...guess what, the nimh guys demand that you run your lipo equiped car at their class's weight limit of 1500g...is that fair? If you now have to run at their weight of 1500g, wouldnt that extra 150g of lead you'll need to add to your car to meet weight decrease your cars performance and put you at a power and speed disadvantage? You'll be running your Lipo at 7.4V @1500g, but they'll be running 7.8V with the current pro matched cells and have more punch and power that our Lipos? Is that fair? Maybe those that run Lipo can run at 4-5 cell nimh weight and thus make it more fair to run against the 6 cell powered cars? That would mean 2 weight limits for each battery type. Or maybe limit the power on the 6 cell nimh so its at 7.4V, like the Lipo?
We are trying to sort this out at our club races coming up and would like to know what you all think...

STLNLST

iTrader: (32)

I hear what you are saying but I look at it like this......the Nihm rules were already written and in place then Lipo came along and rather than turn their back on the Lipo's they were allowed to run (in some places) with the nihm packs but the same weight rules applied. Is it wrong/right.fair....who knows since all of this is so new.People are still debating the brushed and brushless rules and now the Lipo's come into the picture to add fuel to the fire. I'll be running mine in my sedan from here on out.