I've just fried the main board

[Marty]

Help,
I have just got a heng long bulldog and only ran it once, the standard battery was pretty crap and give me only 15 mins worth so I bought a tornado 3300 mah battery and tried that but smoke fire and the such came from the, I think the rx18 now I know I need I new board but was the battery to much and if so what would you guys recommend.
Or did I do something wrong?

Martin.

[MichaelC]

The ampere is only an indication of the capacity and not the voltage of the battery which would be the cause of burnt board. I assume the battery is rated at 7.2 volt and not a lipo ? Using a high ampere battery should only increase runtime as you have original hope. There might be something else at play here.

If you are using a lipo 2S then you would be looking at 7.4v which is slightly higher but shouldn't be a problem. On the otherhand if it is a freshly charge 2S lipo you could be well over 8v which might be the cause. Did it start smoking right after you plug it in or was it after you ran the tank for a while ?

[Marty]

Hi Michael
Thanks for the reply
No it's not a lipo just a standard 7.2
The tank was a grass and got caught up, so would that cause it to fry if the tracks were struggling.
The tank was fine until then, so if it was that would the. Battery be OK to use when I get a new unit?

[MichaelC]

The tank was a grass and got caught up, so would that cause it to fry if the tracks were struggling.

That could be it. Battery wise I have use up to ones rated at 6800mAh with no issues.......

[Roboticus_Prime]

Welcome to the joys of Heng Long!

I have a couple questions.

What voltage is your battery? These tanks run on 7.2v, and the RX-18 is not a very robust board. The good news is that it costs only about $20 to replace.

What gearboxs do you have? Are they plastic? Pot metal? Steel?

Edit. Looks like I hit post too late. Lol.

[Roboticus_Prime]

Hi Michael
Thanks for the reply
No it's not a lipo just a standard 7.2
The tank was a grass and got caught up, so would that cause it to fry if the tracks were struggling.
The tank was fine until then, so if it was that would the. Battery be OK to use when I get a new unit?

Yes. That's called stalling the motors. When that happens, the motors draw more current than the board can handle.

[Marty]

standard everything roboticus.

so stalling the motors (not good)

do you think i might have damaged the motors?
and can i still use the better battery. when i get the new board.

[Roboticus_Prime]

Is it the "metal" version, or all plasitc? If it's the plastic version, the gearboxes should have a slipper clutch to help prevent stalling.

The bulldog has the same issue that the Pershing does. The rear drive sprockets like to grab long grass and pull it.

Are you in the US, or across the pond? That will determine the best supplier of parts.

[Marty]

im across the pond uk,
it is the plastic version, after i untangled it i replaced the battery with the standard 1700 and took the top of the tank, one track sort of worked but the other had no movement at all, the turret moved and gun sounds but as soon as i tried the forward or reverse it just shut down after awhile making sure the motors were free the board started smoking alot and it went down hill from there.
thanks for your help sir you are a gent.

[Roboticus_Prime]

The plastic gears should have a slipper clutch that should prevent that. Was there a bunch of clicking?

Either way, you might take this opportunity to upgrade the gearboxes!

You'll want either the 3 shaft

http://www.rctank.de/31-PRO-steel-gearb ... long-axles

Or the 4 shaft.

http://www.rctank.de/41-PRO-steel-gearb ... ors/18000t

The main difference between the two is that the 4 shaft have a lower gear ratio and should make it harder to fry the board.

Of course you could just replace the plastic ones.

http://www.rctank.de/Gearboxes-with-long-axles

The RX-18's are pretty easy to find on eBay. There are two versions. The 2.4ghz and the old 27mhz with the crystals. Make sure you get the right ones. (It's always handy to have a few spares)