I'm going to do an experiment later. I'll try different voltage cutoff settings on the quark and see if the performance degrades when accelerating.

Would be appreciated.

An eagletree microrecorder is 70 bucks.. nice to play around with.

I'd love to get one of those.... but how many amps can that measure up to.. will it damage if it's an Amperage overload?..

The MicroPower is rated for up to 100amps continuous I think. It has no problems handling more than 100amps though, as I have recorded peaks over 100amps on many occasions.

that's cool then... that'll be my next small purchase...

I haven't done my test yet, but I checked the A123 website. They claim that one cell can put out 189W at 30C, which is the cont. rating. This means a voltage of 2.7V.

Ok. I did a little bit of testing on asphalt today. I set the quark lvc at 3.0V, which is the highest setting allowed. Then I got out my gps and did some acceleration and speed testing. The top speed did not drop any, still 39mph, and the acceleration seemed to be as strong as ever. I ran the truck for about 15 minutes but did not use up the entire pack. There was only one time when the truck stuttered before accelerating, which I guess was the lvc kicking in. Overall, it looks like the packs are able to maintain greater than 3.0V per cell during heavy use, at least on my truck.

Did you put it on auto Lipo or on 6s Lipo? If it's on auto, it might be seeing the 6s A123 pack as a 5s Lipo, which would cut off at 15v.

Hey Metal, what do you mean "auto LIPO"?

I'm still using 4s packs right now. I haven't gotten the other pack yet. My understanding is that the quark automatically detects the number of lipo cells. There is no capability to manually set the number of cells. You can only set the lvc for each cell manually. Since my packs are 13.3V, the quark should detect them as a partially discharged 4s lipo and then set the cutoff voltage at 12V based on my lvc setting of 3.0V/cell.

Very nice truck, I'll have to watch the vid when I get home.

The spec sheet for the A123 cells show they put out ~2.7V at a 40A discharge (~17.4C.) Obviously for a 4600 pack this would equate to 80A, which should be around where you are. Hopefully your testing will prove this.

I'd really to like to run a 5s2p (3s2p & 2s2p) set of these, but a 3s2p batt isn't available from them, and I've heard they are not tolerant of soldering (must be spot welded.) Otherwise you could build this from a single dewalt pack ad it would only be ~$100. Sounds like other retail chargers are coming out for them now. I would be awesome to be able to charge a 2p pack at 20A. :)

Cart: did you have a chance to ask them if more batt configs will become available?

Watched the vid, very nice, just putfile was not playing nice...

I did see that they do have solderless power tubes for M1 cells, but they run $20ea. For my saddle pack that's $40. :(

Does anyone know the approx voltage of a NIMH cell underload? I've seen graphs of ~1.1V, but this is usually under a much lighter load, like 10C. I'm wondering what it looks like in a high amp BL system that is pulling 80A+. For the M1 cells, a 5s pack under 80A would be ~13.5V. A 5s M1 pack seems to equil ~15 cells nimh based on nominal voltage. Thus the nimh would have to drop below 0.9V under such a load for the m1s to be better. Thoughts?

Finnster, where did you see a spec sheet on the M1 cells? I don't know if they are going to offer other battery types.

I wrecked my ST-1 yesterday, and I must say that I am VERY impressed with the durability of this truck. I was going full throttle at top speed in an empty grocery store parking lot. Then I hit the brakes to slow down and nothing happened! The brakes weren't working! About a second later the truck slammed into a concrete wall going at least 30 mph. Amazingly, the only thing that broke on the stock parts of the truck was the screw holding the front chassis brace to the steering plate. My conversion didn't fare so well, though. The force of the impact ripped the motor screws out of the motor, because the motor is mounted facing rearward, and it wanted to keep moving forward after the truck stopped. I think that my screws were too short. The motor slammed into the steering plate and bent a few of the fins. The motor may actually be what broke the screw on the chassis brace. When the motor left its mount, it ripped off one of the gorillamaxx straps. The battery was lying on the ground next to the truck. Also, the motor jerked the quark, and the plastic cap on one end popped off.

I checked the motor, quark, and batteries, and everything still works, so it was only cosmetic damage that occurred. I called quark to ask them why the throttle and brakes were cutting out (I've had the same problems as newuser), and he said to send it in, so I am.

Now I just need to buy another gorillamaxx strap and some longer motor screws, and I'll be back in business. I'm upset that my brushless system got damaged, but thrilled that the truck took the hit so well. My Stampede and MT2 would have been in pieces after a hit like that.

Yikes! :036:


As far as the spec sheet goes, its right on the a123 homepage. It shows a few graphs, one of them being voltage vs discharge. At a 40A discharge (single cell) the voltage drops to ~2.7V.

There are a bunch of interesting battery discharge graphs posted on some of the forums where people data log thier planes. The few I've seen on the M1 cells seem to reflect this.

I agree glassdoctor. I saw those "booster" thingies and immediately thought that it was really not a good idea. It reminded me of this:

http://www.unbelievablerc.com/detail.php?pid=8

Yes. The right solution is to get the proper number of cells. Doing all that stuff to insure proper current flow, and then stick a 10% loss in the line just doesn't make sense to me...just my $0.02.