11 replies to this topic

[bighair]

I have a fighter buggy with Mad Bull wheels. it runs a bigger motor than standard and a Ripmax electronic speed servo. It used to run fine but now the batteries lose their charge almost instantly when I start it up. It seems there must be a power drain. Any ideas?

[mike_o]

Unless something gets very hot (like smoking hot), your battery has lost it's capacity, or isn't fully charged (defect charger).

[Gruntfuggly]

What sort of batteries are they? What sort of charger are you using?

[ideal2k]

Probably your batteries m8.
If one cell goes bad, then you know, a pack of six is no stronger than their weakest link.

[bighair]

I understand what you're saying but ALL my battery packs?

[BiggusDitchus]

Is it the charger, i.e. are your batteries being fully charged? When charged the batteries should be slightly warm. Im also guessing you have no way of checking them in another car/vehicle, to rule out an issue with your esc, or motor?

[ideal2k]

Well, if you have a charger that indicates MAH, and has a discharge feature, you can see if your batteries are really up to it or not.
Then if you don't, go to a friend who has one.
If the batteries are functional, then most likely the problem would either be the motor condition, or binding somewhere in the drivetrain.
Being a mad bull, I doubt it would suddenly develop binding. If so, then it would be something like grass or a piece of string wrapping around the wheel hub, so just take the rear wheels off and check if something has wrapped around the axle near where the shaft comes out.
Then you want to take the motor out, pull the brushes out and have a look at them, take the endbell off and inspect the commutator surface.
If it's discolored/black or pitted, or the brushes are very short and discolored/purple, then that might be a source of a problem.

How old are your batteries though?

[bighair]

Bit of an update. Managed to get one of the packs to take a charge. 5 mins or so of running it ended up with battery pack hot, esc heat sink hot and wires between the two VERY hot! Does this suggest that the batt pack is dodgy?

[wolfdogstinkus]

Could it be the connector?, I had a worn out tamiya connector that did that. The wires and connector was too hot to touch.

[mike_o]

Bit of an update. Managed to get one of the packs to take a charge. 5 mins or so of running it ended up with battery pack hot, esc heat sink hot and wires between the two VERY hot! Does this suggest that the batt pack is dodgy?

Wires between ESC very hot, too? If not, then it's your ESC that has partly blown a transistor.

[metalmickey0]

Wires between ESC very hot, too? If not, then it's your ESC that has partly blown a transistor.

First thing i`d do in bin the Tamiya connectors as they are s****(totally rubbish, polite version). I melted a pair together many moons ago.

[GregM]

I have a fighter buggy with Mad Bull wheels. it runs a bigger motor than standard and a Ripmax electronic speed servo. It used to run fine but now the batteries lose their charge almost instantly when I start it up. It seems there must be a power drain. Any ideas?

Unfortunately, the gearing of the DT-01 chassis is not really suited to large diameter wheels like the Mad Bull's Lunchbox tires. The smallest pinion you can fit is 17 tooth, while other Tamiya models with Monster Truck wheels (like the Blackfoot, Lunchbox and Monster Beetle) uses 10 tooth pinions to make up the wheel diameter.
Fitting a powerful motor to a Mad Bull can result in motor overheating and thus quick battery drain, especially when running on grass. For brushed motors in a Mad Bull, I would not go faster than a Sport Tuned motor, or use a similar more effecient (and less heat producing) motor. Don't forget to attach a passive motor heat sink or an active motor cooling system. Maybe your motor itself has been damaged recently?