Battery self discharge and storing bike best practice

[patmurris]

Hi all,

I bought a CE-02 three month ago and i noticed the traction batteries do lose about 2% charge a day. I know this is the CE-04 section, but i believe it's also relevant (and so far i've got nobody to talk to in my section...).

Now this is not a big issue on a daily basis, but what if you don't use the bike for several weeks or month? That will probably happen to me next summer.

I'm curious to know whether the CE-04 also does lose charge, and more importantly, what are the recomanded best practice in that regard.

Should the bike stay plugged? Should the batteries be physicaly unplugged like we used to do on cars back then? Is there an option i don't know about for "deep sleep"...? Can the batteries dry out and suffer damages?

Thanks for your feedback and experience.

 

[Mitleider]

Great question. At the onset of Winter, I charge my scooter to 80%, and I attach a smart charger to the auxiliary 12V battery. Then upon the arrival of Spring weather, I'll attach the main charger and bring the charge up to 80% if needed, check tire pressures, remove trickle, and off I go.

 

[patmurris]

@Mitleider: That makes sense. How much does the traction battery lose during that time?

My understanding is the 12V battery powers the lights, heaters (not sure), bike's brain and all the associated sensors and communication extension. The traction battery in turn will top off the 12V battery when needed. Left alone i don't think either batteries would self discharge much. The drain comes from the no so quiete sleep the bike/ev vehicule pretends to be - checking this, checking that, computing, calling home, heating or cooling that... Without trying to understand it all, i would be inclined to unplug everything and let it be... Would that be harmful?

 

[Mitleider]

My 12V battery went completely dead leaving me stranded once....so much for the theory that the propulsion battery will reliably tend the smaller one. I hear this from electric car owners on occasion, too.
My scooter had to be towed, which damaged it, and the dealer replaced the 12V under warranty and installed a trickle dongle..

 

[subcyclist]

"...if you don't use the bike for several weeks or month? That will probably happen to me next summer."

The most important consideration in this situation is the state of charge of your battery. Mitleider stated that he stores his bike for long periods at an 80% state of charge, which is best practice for maintaining good health of the battery. Ambient temperature fluctuations change the energy level of chemical batteries. If temperatures drop significantly enough (5 degrees celsius), the voltage of the battery will also drop; this will not necessarily damage the battery, it will just reduce the charge level. If, though, the battery is at a high state of charge (e.g. 95% or more) and the ambient temperature increases significantly, the voltage of the battery will increase with it, and there will be little to no 'room' left in the battery for a voltage increase. This can definitely damage a chemical battery. For your time away next summer, this is the most important consideration. To leave your bike for one month at 70-80% state of charge is ideal, just as Mitleider wisely does.

To take care of your 12v battery, you could choose to purchase a 12v battery charger, commonly used for cars. This will allow you to check the state of charge of your 12v battery periodically (once per month), which can prevent you from being surprised by a dead battery one day; you can check its health over time to know when it needs to be replaced. I bought one of these for my last combustion engine car that I owned, which helped me to identify a dying battery when it was 4 years old (I lived in a hot region in the US, causing a short life). This eliminated the surprise dead battery, as I could see when its charge state was declining over time. Also, these chargers can help to 'jump start' your bike. If you leave for one month as you have planned, and return to a dead 12v battery, you can connect the charger for 5 minutes or so, and then you will be able start your scooter. You can then ride it somewhere to have the 12v battery replaced. So, this type of charger will help you to maintain your 12v battery to prevent a surprise dead battery incident, as well as help to start your bike if you do return to a dead 12v battery.

Bon Chance!