YHR

Mustclime was having trouble with his DBC. I pm'd him and got some info about the trouble he was having. Basically he was running a big heavy tank with 400's. His DBC was really quirky with it resetting itself and LED's coming on when he turned the turret. I have experienced all of these things with a low battery. or when I left the Heng Long track recoil on. The sudden draw of amps to the drive motors would brown out the DBC electronics and cause it to go goofy. In Mustclime's case though he is running a freshly charged 5000 MaH battery. Battery should be no issue.

However because of the weight of his tank, the motors he is running plus the Benedini I figured the amps being drawn through the RX 18 were just too much, and the DBC was getting browned out when he climbed hills or added extra load.

Tonight I went down to the workbench and found what I think is the solution. Very simple, and this will work for all DBC's.

The trick is to supply power to the DBC from another battery source. In this example I am using an old receiver battery set up.



I soldered a connection point to the "+" and "-" on the command cable socket on the DBC.






I removed the wire from the 3 wire command cable that normally supply power to the DBC3.





Just plug in the receiver battery onto the DBC to supply power to the DBC3. You now have a separate power supply to the DBC



Tonight I ran my Leopard with the Heng Long recoil on( this would normally freak out the DBC). I was able to fire and watch the tank jump back time after time with no ill effects and no funny behavoir from the DBC. From my limited testing this looks like it works. I would like to encourage Mustclime to give this a try and see if it solves his problem,

If anyone else out there is experiencing some quirky behavoir from their DBC when the battery is running low I would suggest they look at this as a possible fix. I run stock motors and 3:1 gears and have no issue wiht the DBC when I shut off the Heng Long recoil. If however you have done some mods to your tanks that really draw amps, and you are finding the DBC giving you grief, I believe this will fix your problem. IF others were having problems and this fixes the issue please let me know

Cheers

ausf

I would experience that occasionally myself with a half full battery if I was climbing or putting in a heavy load. What I would do was run until the anomaly, then use the battery in the Tamiyas to finish them off. I didn't really mind it, getting 30 minutes at WOT with the Benidini, Amp and 400s is very reasonable, but adding another 20 to that with use of another smaller battery would be great.

I assume a separate NiCd or NiMH at 7.2 would work too or even a 7.4 lipo?

Pah co chu puk

With no off switch for your new power supply will the main tank switch still turn it off? Would it hurt the DBC to leave the power attached all the time our would I need to un plug it for storrage / transport?

Would a 9 volt battery work just as well?

YHR

Yes Remember it is this battery that is now driving the Benedini sound. Not sure how long you get with a small receiver battery pack. I know you can drive one of those amplified ipod speakers all day long on on three AAA batteries, so I am assuming this battery pack will drive the Benedini for as long as the tank battery lasted.

I have a 7.2 Volt 600 ma pack out of the WSN Halftrack I am going to use when I am going to get real serious about a tank battle. Again in most cases this isn't an issue, but if for some reason you are experiencing anything flaky with any of the DBC line, consider this as a possible fix.


One other fix might be just the gauge of wire a guy uses between the battery and the RX18. Perhaps less resistance in the wire would be enough to prevent the problem? Maybe that is why this experience isn't universal. That would even be an easier fix. Use the same guage as the wire on the charging plug. Maybe the current is choked in the small wire, and when there is an excessive amp draw you just can't supply enough power to everything that needs it. The DBC with its digital signaling is more sensitve to this. This might also explain why the Tamiya has the mystery reset as well. Same kind of thing happening. Just a thought.

YHR

You would either have to wire in a switch or unplug the battery when not in use.

The DBC has a 5 volt regulator on board to supply voltage to all the components. I think those things can handle up to 25 volts of input voltage, so a 9 volt battery shouldn't be an issue, I just am not sure how many amps are stored in a 9 volt battery.

ausf

Sweet.

I have a bunch of Turnigy 850mAh lipos I use for the Ketten. I get about 30 minutes of running them around before they drop to 6.8, so I'd imagine they'd run the Benny and DBC for a long time since there's no motor draw. The size is about half that of the receiver pack you have there, so they will fit in tight spaces. I'll back up your testing here this weekend.

I assume this is why the Tammy Tigers first came out (maybe still, I don't know) with two 7.2 packs needed, draw to weight. My M4 used to get a solid 25 minutes of of 1 1900, but the Tiger used 2 1500s for maybe 20 minutes or so.

Pah co chu puk

I just put a meter on some batteries on my work bench and got these readings...

9v 8.7v @ .96amps
4 AA 5.4v @ 7.65amps


How many amps @ 5+ volts does the DBC like?

YHR

That number for the 4 AA seems pretty big?

The DBC requires little amperage but it needs a nice steady clean supply. If you are not running a Benedini then the DBC does not require much at all. Probably if you are just running the DBC2 a 9 volt battery would be fine. As a side bar I thought I noticed a decrease in the whine and interference from the ESC FETs on the sound system. So DBC2 owners with the basic sound board may want to look at this as a method to reduce the RX18 whine as well.

YHR

Just an update to this.

I tried the capacitor pack from Hobbyking to see if they would work, and they don't. So if you are having glitch trouble with your DBC, or any electronics, the cause is most likely the tank electronics demanding more current then can be passed from the battery or through the wiring.

This set up demo'd in the pictures above works. You might want to add a switch in the harness to allow you to turn off the power to make it easier on yourself.

A good example of why you should use thicker wire. This also builds a case for the use of Lipo's as they can really put out the power when needed and handle this demand.