Need Diagnostic Help

[firenice]

I have had my Raider for about 7 months. I have used It about 20 times. Had loads of fun. But then it would run a short distance and stop. I recharged it and It did the same thing. It didn't seem like a mechanical problem so replaced the 2000 mah battery with a 3000. And it ran faster and longer. Whoopee! But after 3 or 4 runs it did the same thing. Does this problem sound familiar to anyone?

 

[Unusual RC]

Hi there firenice!

In order to diagnose correctly we need more information.

I presume you have the stock ni-mh battery?
And you replaced it with another ni-mh battery with 3000mAh capacity?
Is it 6 (7,2V) or 7 (8,4V) cells?
Or do you have a 2S lipo (7,4V) battery?

What is the version of your Raider?
Mega, BLS or BLX (XL)?

What is the charger you use?


First thing which comes to my mind is battery condition, if we talk about a ni-mh type of battery.
If you use the default wall charger, it might just be it does not charge well anymore.

Another option could be that your ESC is set to lipo instead of ni-mh.

But this is pure speculation without more detailed information.

 

[firenice]

Thanks, for your response. I have a Raider 1/10 scale 2WD Mega Desert Buggy. The original battery was a 2000Ah (7.2V) NIMH. I replaced it with a 3000Ah (7.2V) MIMH. My charger is a Thunder AC6. The jumper is set for MINH.

 

[Dustin Mustangs]

Do you have a way of checking voltage? If so, check battery voltage when done charging, while under load in the vehicle, right when the problem occurs, and after it happens once the battery has had a chance to rest for a while.

If not, and you plan to be in this hobby for more than a brief period, it would be worth investing in a multimeter like this one:

http://m.harborfreight.com/7-function-digital-multimeter-90899.html

 

[Unusual RC]

Thanks, for your response. I have a Raider 1/10 scale 2WD Mega Desert Buggy. The original battery was a 2000Ah (7.2V) NIMH. I replaced it with a 3000Ah (7.2V) MIMH. My charger is a Thunder AC6. The jumper is set for MINH.

Thanks for the detailed response!
This is information we can use to diagnose your "patient"

I do not know the Thunder AC6, but

Thanks, for your response. I have a Raider 1/10 scale 2WD Mega Desert Buggy. The original battery was a 2000Ah (7.2V) NIMH. I replaced it with a 3000Ah (7.2V) MIMH. My charger is a Thunder AC6. The jumper is set for MINH.

Your charger is a good one.
Please check how much mAh goes into the battery. Your charger can show this on the display. Monitor after you have "drained it empty" with your car.

A 2000mAh battery should have something between 300-600mAh left (20-30%), which means roughly 1500mAh should go back into it. However there are electrical losses during the charging process, so devide by 1,2 to get a more accurate number.

Still your charger is on the suspicious list too, since both batteries display the same issue. The chance both batteries are bad is smaller than just one.

What could be another cause is the condition of the low quality 15t Arrma mega motor.
The already poorly designed brushes can be worn so much that they cause excessive power consumption.
If this is the case, your batteries are drained as described above and can be recharged with 70% of the total capacity.

Another option can be that somewhere your drivetrain has too much friction, or maybe a wheel (bearing).
You could check that too by removing the motor pinion, and turn the wheels by hand.

 

[lonee]

I also do not know this charger, but maybe he changed the settings in the charger.
The first description sounds like low voltage cut off.
After he replaced the battery with the bigger one, the first run was OK. So I guess that battery was good.
AFTER charging he had the same problems like with the other battery before.
So I suggest to check the settings concerning cells in the charger. It must set to 6 cells or 7,2V.
Maybe fire nice has the option to charge his battery´s with an other charger of an friend.
Than we know what happens. I don´t think that something happens with the motor, cause if there a problem, it will occurs also with an new battery. .... And it´s getting hot and smells....

Regards,
lonee

 

[Unusual RC]

I also do not know this charger, but maybe he changed the settings in the charger.
The first description sounds like low voltage cut off.
After he replaced the battery with the bigger one, the first run was OK. So I guess that battery was good.
AFTER charging he had the same problems like with the other battery before.
So I suggest to check the settings concerning cells in the charger. It must set to 6 cells or 7,2V.
Maybe fire nice has the option to charge his battery´s with an other charger of an friend.
Than we know what happens. I don´t think that something happens with the motor, cause if there a problem, it will occurs also with an new battery. .... And it´s getting hot and smells....

Regards,
lonee

I totally agree.
Did not read the opening post carefully. Indeed this could not be the motor already (but it is not a great performer, low quality and wears out quickly).

Once I charged a ni-mh battery on the ni-cad setting. This caused the auto cut-off (of the charger) to come in at less than 50% full.
Maybe you should check that!

I think this charger has the same menu as a IMAX B6 (or one of the trillion copies available). And if so, I checked that the ni-cad charging menu is separate sub-menu. It is before of after the ni-mh sub-menu.
It auto detects the number of cells.

There is no problem charging a ni-mh according to ni-cad settings. But you should not use it to discharge your battery, and be careful not to use high charging currents.
One bug difference between ni-cad and ni-mh is the way their charging cycle goes. The auto cut-off (delta peak) is different, which can cause the ni-cad program to "think" the battery is full way to early. Have had it myself a few times with a 4500mAh 7,2V/6S

 

[mansour545]

Hi

As one of my previous experiences with almost same issue..
Do you run your car in hot weather? Like 35-45 C?
As I did before destroyed a couple of batteries and have no fun after I realized that the motor have gone beyond maximum temperature and got demagnetized. Therefore, to run after demagnetization the motor will draw much higher current to get the rotor moving and higher current will damage batteries First and ESC if exceeds the max ESC current rating. Then the batteries will seem to be okay with cheap chargers and charg maybe even faster than before or much much slower in time indicating a failure in batteries.
One easy way to find out if the is the problem is to remove motor gears and connect an Ammeter in series going from battery + to ammeter + then ammeter - to ESC + then ESC - to battery - closing the loop then see the motor specs there should be a (no load current) then pull throttle and see if that current reading is the same more or less but not big difference then you will know that if it's the motor needs to be replaced or then check your whole system with new lipo pack and see if the current still higher than rated then it's definitely the motor if not then your batteries may have exceeded rated temperature and they are no more giving you the needed voltage nor mAH then you need new batteries.

Happened to me with my traxxas stampede and replaced the damaged motor with castle creation mamba X SCT pro combo. Working fine since then.


Hopefully this benefits you.