Several things can cause the now poor performance of your NiMH battery (does not apply to LiPo batteries)
1. Age of the battery / number of charge cycles:
Over time your battery will lose performance, depending on the quality of the battery and how it is used and maintained.
For the best possible lifespan, it is important to let the batteries cool down after driving – and also before and after charging them.
2. The battery has been “worked hard”.
If the battery has become very hot while driving, in the “worst case” it can simply melt together.
This typically happens when the car's ESC/motor is really pushed – for example when driving in grass or with repeated start/stop.
Over time this will also greatly shorten the lifespan of a battery.
3. The battery has been left unused for a long time.
If the battery is not used, the run time can drop considerably.
So it is a good idea to use your battery “now and then” – for example once a month.
Can I do anything to extend the run time of a battery with short run time?
Yes, there are options, such as discharging and then charging the battery, repeated about 3 times.
This exercises the battery's cells, and in many cases you can get much of the lost run time (mAh) back again.
If you have a more advanced charger, it can typically run this “exercise” / cycle.
It will then charge and discharge the battery the number of times you set.
If you do not have an advanced charger with this function, you can do the following:
* Charge the battery with the supplied charger.
* When the battery is fully charged, let it cool down.
* Then put the battery in the car, switch the car on and drive until the battery is completely flat, i.e. make sure all the power in it is used.
After that, it is fine to leave the car switched on until it runs completely out of power by itself.
* Let it cool down.
… repeat this 3 times.
After this you will typically notice an improved run time.
If not, it is usually time to look at a new battery.
If your charger also has no auto-stop – i.e. it does not stop by itself when the battery is fully charged – you can work out the charging time like this:
If the charger's “output” says 500mAh and the battery is 3000mAh, then it is simply 3000/500 = approx. 6 hours you need to charge the battery.
