How to Know When Your Hybrid Battery is Failing

The Red Triangle of Death

There are several subtle cues displayed by a hybrid vehicle that can alert you to degrading hybrid battery capacity & performance. They are the things that can help you know when your hybrid battery is failing. If not acted upon, the battery will ultimately display a fault code for battery ‘failure’. By paying attention to the warning signs and performing preventative care on the battery before it ‘fails’, you can easily improve battery health and prolong its life. Our hybrid maintenance and service procedures will improve your hybrid battery performance, and save you thousands in avoided hybrid battery replacement and associated costs.

The Signals that your hybrid battery is failing

1. Reduced Fuel Economy

The main indication of decreased battery performance is a reduction on fuel economy and diminished vehicle performance. The vehicle does not get the same fuel mileage that it used to and it feels sluggish – lacking in power during acceleration. This happens because as the hybrid battery weakens, the vehicle is forced to use less of the battery and more of the gas engine. It also spends more time charging the hybrid battery in the background (i.e. not shown on the dash). Both of these behaviors reduce fuel economy.

2. Vehicle Switches from EV to Gas Mode Sooner than Normal

If equipped, EV mode may be less frequent and for a shorter duration than when the vehicle was newer. A weakening battery will not allow the car to run on EV mode for very long. The vehicle will thus be switching from EV to Gas mode after a very short time of using the battery since it can’t provide sufficient energy to power the motor.

This can last for several months as the battery weakens and fuel economy/performance progressively decreases. Note: sometimes under-inflated tires can cause similar symptoms. We recommend checking your tire pressure to be sure that is not the cause of the decreased fuel economy.

3. Negative Battery Recalibrations

Negative battery recalibration manifests in a similar way as a parasitic drain on the 12V auxiliary battery. It is initially seen when parking the vehicle over a week or so. You will note that before you park your vehicle the dash battery display shows a nearly full to full battery. When the vehicle is finally started, the dash battery display shows an empty or nearly empty battery. The state gets worse as the battery weakens and it can happen even overnight. This is a clear sign of a weak battery that needs attention soon. If ignored, the battery will soon progress to the point of failure. However, if you bring it to us for service and maintenance before the battery degrades further, the success rate for recovering the pack and restoring it to good operating condition is nearly 100%.

4. Fluctuations in the state of charge

If when driving you notice a sudden drop from nearly full to near empty with large swings in the charging rate, your hybrid battery is failing. The gas engine then revs to a higher than normal speed. It is doing so to try and force charge the battery from empty to full. Note that this is a negative battery recalibration case, only that this is occurring when you are driving. This event is easily visible on the dashboard battery display and you can hear the loud, unusual high idling of the gas engine. When the battery gets to this level, it is clear that there is a serious battery issue since the usable battery capacity has significantly reduced.

That, however, doesn’t mean that all is lost, we can still recondition the battery for you. If you bring the battery to us early enough, within the first few days, the success rate of recovering the battery pack and restoring it to good operating condition is about 90%. Continuing to drive in this condition for over two weeks will cause the red triangle of death to come on. If you still pay no attention to it, the vehicle will shut off while you are driving. We can still help you even at this point, but the success rate of the reconditioning will be lower.

5. Auxiliary Battery Running Low on Charge

While the 12V auxiliary battery can run low because of a number of other reasons, it can also be an indication that your hybrid battery is dying. A DC-DC converter that gets its power supply from the high voltage hybrid battery charges the 12V battery. So when the high voltage battery is low on charge, there won’t be enough power to charge the 12V battery.

As seen earlier in our post on why hybrid and electric batteries fail over time, it is clear that batteries don’t last forever, but they are supposed to last the duration of your hybrid vehicle. If for the reasons stated in the aforementioned post the battery degrades faster, you can always extend its lifetime by servicing it well and taking it for reconditioning. Feel free to engage us for any query and more information on hybrid battery service, maintenance, and reconditioning.

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