The stickers were a good 2 and a half hours of work to apply. The sticker vinyl was surprisingly durable, and sticks very well. However, even though the vinyl is I believe .05mm thick, I didn't want the sides of the stickers to look white (the vinyl sheet is originally matte white printed with the black pictures and a pure black surround on all sides), so after cutting them out with an X-Acto knife, I colored the edges of each sticker with black Sharpie, then let it dry a minute before applying. I think it turned out pretty good.
I decided to make me a GNX, why settle for a regular GN?
Thanks, sandkil. I had to take pics with flash off as the flash reflection was pretty bad. I'll need to trim down the body posts next, then source a battery, ESC & motor. I'm leaning towards a 1S LiPo, 35A ESC and 17.5T motor...does that sound suitable for a 1/12 pan car?
So considering a battery for this car, and suggestions to use a 1S LiPo with a 13.5T motor, I browsed about HobbyPartz.com and had this idea...I could pick up a saddle-pack like this, but only use one of the cells. That way I'd essentially be getting 2 batteries for the car, for $39.95...only about $10 more than the cost of buying a single battery. I suppose using only half the pack would mean the capacity would be 2550 mAh instead of 5100 mAh, but that should be pretty sufficient run-time with a 13.5T motor.
One battery out of the saddlepack should stay at 5100mAh and have a voltage that gets cut in half to 3.7V. Which is what you'd be looking for in a 1/12 battery.
If it was mAh that got dropped to half then voltage would stay at 7.4V and that would be no good.
Phin wrote:One battery out of the saddlepack should stay at 5100mAh and have a voltage that gets cut in half to 3.7V. Which is what you'd be looking for in a 1/12 battery.
If it was mAh that got dropped to half then voltage would stay at 7.4V and that would be no good.
Thanks Phin...I would've thought that both voltage & capacity would be 50% if only using one half of the saddle pack...
no, in series the batteries must have the same capacity, which is what the pack will be rated at.
Say you had some weird 7.4V battery series setup where one 3.7v cell was 2500mAh, and one 3.7V cell was 5000mAh. Now pull 2500mA out of the pack; it will take 1 hour to discharge the first cell, but in series, it will start dropping rapidly, while the second pack is humming along with the capacity to run for another hour at 2500mAh. the pack would essentially die even though the second pack would have capacity. the first cell drops, the second is still at 4.3v or whatever, so the pack voltage overall will decline.
this is why it is necessary to balance lipo packs, because in that scenario, the first cell will discharge below safe levels and essentially be killed.
the old saying, the chain is only as strong as it's weakest link holds true in multiple cell packs built to increase voltages. Cells in SERIES plus to minus <> plus to minus add up to desired voltage and must have matched capacity, this is why all the old nicd cells were sorted and matched together and you paid the price for the best packs.
NOW, you could take those cells, put them plus to plus, minus to minus, and then wire them to the load, and the capacity will add, not the voltage, therefore, you will have achieved a 7500mAh 3.7V pack.
That makes sense, thanks for the explanation. This will be the first time I'm dealing with a 1S LiPo, let alone break up a saddle pack into 2 individual batteries. Usually I'm good with the math.
It seems my early-version Castle Sidewinder ESC may have a compatibility issue with 1S LiPo. It was working fine in another car on 2S LiPo, makes beeping noises and flashing lights as expected when turned on, but I get no beeps at all when starting up this car and one 3.7V LiPo (half of a saddle pack). It *does* flash all the lights and I can calibrate it just using the lights, but there's no beeps. After calibrating, the correct lights function when I give throttle or reverse, but nothing outputs to the brushed motor. I tried a different brushed motor with the same results, so it's unlikely that the motors are the culprit.
I've also played around with settings with the Castle Link software and another thing that makes me think 'compatibility issue' is when I select "Custom" for low-voltage cut-off, the lowest value I can choose is 4V, which is way too high for 1S LiPo. (The default is "Auto LiPo", which is supposed to use 3.2V per cell, but I think this ESC is expecting at least a 2S LiPo to be connected.) I even tried no cut-off but still no output to the motor.
Do any of you Castle gurus know if this is the case? I have another ESC I can try but I have no idea what the make/model is; it's a sensored unit but I'm running unsensored & brushed motors, I don't know if it'll even work.
Since I seem to have run into an obstacle with ESC & 1S LiPo compatibility, I gave up on finishing the electronics and began fabricating a custom battery hold-down. It has been quite a challenge as this chassis was never intended to house a hard-case LiPo. I found that the battery was taller than the lateral carbon piece by just enough for me to cut out an L-shaped piece of carbon, then bolt it to the lateral piece to keep that corner of the battery positioned. I'll use the closer screw-hole to add a tab over the top of the battery which will screw down with a wing-nut or something.
I decided to butcher an old computer tower I/O slot cover as it had an L-shape already formed into it, and it's very thin, and seems strong enough to not bend too easily. I made corner tabs in each section and used a file to round the corners and smooth all the edges. The battery will fit like a glove. I sanded it down and it's waiting for a coat of SEM Trim Black to dry. The foam tape at the top right corner of the battery is just to protect it from abrasion when it's pressed snugly against the L-shaped piece.
All that's left to figure out is a way to secure the front of the battery.
