XRAY - Model racing cars

Intresting, but it looks heavy.

IT IS .3 OZ lighter than a 1400 5 Cell flat Packl. I know it looks heavy, but take the end with the orange off. That is just a device to hold the battery into the drill. First you undo the decal that wraps the case. Then there is two tabs on the end with the orange button. As soon as you bend those tabs out the end comes off and you can throw it away. The other end stays intact. The case is made of composite graphite. The same stuff that 1/10 scale offroad cars are made of.

Here is some pics, I will be breaking down a pack step by step to show exactly how to do all modifications. Not that difficult, but I could streamline the process for you.

IMG]http://i299.photobucket.com/albums/mm312/robknasel/IMG_9860.jpg[/IMG]





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rob

good find bro keep us up dated

leon

This is the Charger, as mentioned above the charger and pack combo is roughly $32-34 at Wal Mart . The great thing about this setup is that you can literally take the pack out and put it on the charger in just a few seconds. If you are worried about the radio case not being as water tight as before then simply just put you receiver inside a balloon and zip tie it. The pack does a nice job of keep debris out of the case. You will have to trim the case just slightly to make the fit not so tight, the big thing is the rear of the case has a small notch that sticks out and that definately needs to be trimmed off.

Rob Knasel

Are you using them without voltage regulator? Its kinda risky I think. Your Rx and servos might survive but maybe not all. And almost all batteries give out higher voltages when they are warm or hot, so do the A123. Check the charts.

So when you drive in hot summer day you get extra voltage from the battery. Ok, maybe not extra but higher voltage for longer at least. All electrics are hot. Your servo works on high voltage thus with higher power and going even hotter than usually. All this makes quite risky I think.

But I wanna hear also how you'll do with this upgrade. I was thinking the same thing last night but with a voltage regulator and they work 90+ % efficiency so the extra 10 gramms aren't a issue.

I originally used a LIpo voltage regulator because of the worry the voltage would be too high. The voltage on a fully 5 Cell 1400mah 6V NiMH pack is usually about 7.2v when fully charged. It will stay there for about 30 mins then start to drop. The A123 cell pack will go to 7.2V and then drop to 6.8v to 7V within about 5 mins and then with stay at 6.6-6.8V during operation. The voltage discharge curve at 5 amps is extremely flat making the power extremely consitent. After some tesing I felt the Regulator was wasting energy even though 90% efficient. I felt is was a unecessary. Airplane guys have been running these cells with no voltage regulators with great sucess. I had backed up my testing with their real world results. Alot of regulators that you can buy for nitro vehicles will come in a regulated 7V model. Also there is a built in regulator in most receivers that help to maintain proper voltage.
For example: From Futaba FAQ SheetVoltage out is based on Voltage in. Receivers typically operate on a 4.8V DC input voltage. This can be increased to 6.0V, where more power and speed can be derived from attached servos, but a decrease in lifespan for said items might result as well due to increased stress. An ABSOLUTE minimum operating voltage is very near 4.0V. Rx's typically use a 3.3V regulator which requires an additional 0.7V to power itself, resulting in the 4.0V minimum. In application, however, it is typical for performance to become severely degraded as power falls under 4.3V DC.

I dont agree about voltage increasing at a considerable amount due to ambient temperature. Voltage is usually increased by a overcharging that causes internal cell chemistry temperature to increase. That is the really good thing about the charger that is included. It is a very slow charger, and the pack has a built in thermal sensor.

I appreciate everyones comments please keep them coming. I do agree this is pushing the envelope on voltage but beleive me that a 5 cell NiMh pack is nowhere near being a 6 volts.

Please everyone charge your packs then post the voltage you read following charge and then 10 mins, 30 mins.

Thank You,

Rob Knasel

Hello,

Just want to add up my experience of using this knid of battery.

If I'm not wrong the battery is categorize as Li-fe or Li-fp or A123.

I knew about this battery from another XRAY Team Driver in Singapore and I would say that it was very interesting to try.

Up to this moment I already use this kind of battery for 4 races and it shows a very good performance. In 60 minutes main final, the servo movement doesn't felt weaken.

I also don't use regulator becasue the voltage is similar to regular Ni-Mh cell.

My electronics are consist of 2 FUTABA BLS351 with FUTABA FASST system, which is considered more power consumption than the crystal system. The battery will last about 80 minutes so at the moment this battery is very very good for me..

One thing that I would like to add up that I use bare cells, I mean that there is no outside cover so that the with a little modification the original battery lid is able to be use.

I only grind a little bit of plastic in the top of the battery lid. And later I will try to mill out some plastic at the bottom of the battery compartment.

Stanley,

Do you make your own packs?

What charger do you use?

I'm interested in these cells because being involved in the building industry I know they are tough as nails. The lipo's seem a little fragile to me.

Thanks

I already milled out the battery box it will save you about 20 gr.

I have a friend that decided that he like the idea of putting the cells in the radio box with the original cover. You could just strip down the case and heat shrink cover the two cells. In the radio box you would just have to barely cut out the bottom of the battery box side to allow the round cell to drop a 1mm or 2mm to allow the cover to be put back on. His idea is to solder a servo plug on for the three wires on the one side of the battery (this is the thermal sensor and balancing tabs) and put a micro deans on the power side of the power leads. You could modify the original charger and put these same wires on the charger tabs. Not really that hard to do. In fact he thought that you could throw away the original charger case and probally put two to three of these chargers in a small electronic project case like Radio Shack offers. I would get a plastic case.
Let me know if anyone does this.
Thank You,
Rob Knasel

Good job Rob, Keep us posted on how it works out.

I've been trying to find some of these packs and it doesn't look like Black and Decker bring them in to New Zealand. Had a quick look on ebay, there are a couple, but expensive freight. At US$20, if I can buy direct in New Zealand they'd only be about NZ$25, which is cheaper than a NiMh pack. If anyone can point me to a place which will freight international cheapy, let me know.

The Duratrax Ice can charge Li-Ion, so I should be covered with charging.