FAQs - 4QD - Electric Motor Control


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If you don’t think your battery life is all that it should be then;

  • Check the battery condition. The capacity of a battery reduces as it gets older. Also do a load test on it, we’ve seen batteries that gave 12.8V off load but that dropped to 11.1V as soon as a load was applied.
  • Check the condition of the power cabling. We’ve seen numerous cases where cable joints have degraded over time, overheated, and then caused a significant volt drop at the controller. Measure the voltage directly across the controller B+ & B- terminals whilst under load.
  • Is there mechanical drag in the system?
  • If all else fails, fit bigger batteries.  The controller can only do only one thing with the current it takes from the battery – pass it on to the motors. If the controller wasted any significant power – it would simply get hot and go up in smoke, so if the batteries don’t last – it’s a battery, a motor, a wiring, or a mechanical problem.

There are two types of lithium battery to consider;

1] The lithium polymer type, called LiPo in the radio control world. These are small, light, and have a large energy capacity. One significant issue with these is that they must not be discharged too deeply, if they are then they can be damaged.

2] The lithium ion lead acid replacement type [LiFePO4]. These are usually a higher capacity replacement for a standard lead acid battery and very common in the golf buggy world. These usually work ok with 4QD controllers but some batteries have internal protection circuits that can cause unexpected results e.g. over current protection, and low voltage cut-off.

4QD can support operation with lithium batteries as follows;

  • The Pro-160 has a fully configurable low battery alert [+/- 0.1V] and 50% limp home mode.
  • The 4QD-200 / 300 have an adjustable low voltage cut-off.
  • The DNO can have a simple modification done to set a low voltage cut-off.

Our BCM-5P1 battery meter has a battery protection feature which can be used to turn a controller off to prevent damage to expensive lithium batteries.

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