Charging an E prpulsion battery to 60 percent

[FairweatherDave]

60 percent is the ideal level for long term storage, and I have just had the pleasure of a 90 percent discharge to the Horse and Jockey near the top of the Hamble. I can't see me using the motor for at least 3 weeks. Should I aim for a partial charge to about 60 percent (if so any method recommended beyond trial and error) or go 100% full charge. Apologies for the slightly pedantic question !

 

[Bouba]

60 percent is the ideal level for long term storage, and I have just had the pleasure of a 90 percent discharge to the Horse and Jockey near the top of the Hamble. I can't see me using the motor for at least 3 weeks. Should I aim for a partial charge to about 60 percent (if so any method recommended beyond trial and error) or go 100% full charge. Apologies for the slightly pedantic question !

If I recall correctly....even if you store it fully charged..it will self discharge when in storage

 

[jlavery]

If I recall correctly....even if you store it fully charged..it will self discharge when in storage

That's what I understand too.

 

[penfold]

What do the makers say? A lithium battery will not self-discharge to any meaningful extent in a month.

 

[FairweatherDave]

Thanks Bouba and jlavery , your understanding is my understanding (and you have contributed to my understanding in previous threads too ).
The FAQ bit on the E propulsion website doesn't get into any great detail, to answer penfold. However what I can say is I fully charged my battery not too long ago, perhaps 22 June. I then did a short trip on the weekend of 24th (10 minutes each way to my boat). I didn't check my battery level until 8 July but 60-70% is what I had, and I concluded there had been some self-discharge, more than I expected. Despite that we did the 10km plus return trip to the Horse and Jockey, with a bit of rowing, tidal help and not fully throttling the motor.
The nuts and bolts of my question is really has anyone partially charged their battery deliberately to get to around 60%? It just feels a bit wasteful fully charging in the knowledge it will self-discharge to the level it is happy with.

 

[lustyd]

What do the makers say? A lithium battery will not self-discharge to any meaningful extent in a month.

Many of the better devices these days do it on purpose. Certainly my drone batteries will self discharge (even if disconnected) to storage level on their own using an internal resistor so it's impossible to keep them fully charged for future use. It's maddening when I want to use the drone and have to charge it every time, but after 3 years with little use over lockdowns the batteries are as good as new so overall seems a good thing.

From the e-propulsion website Marine Electric Batteries | electric outboards & electric marine motors:

The built in Battery Management System means that the cells will only discharge to a maximum safe level to protect and extend the battery life. When not in use, the batteries will ‘hibernate’ and discharge themselves, so there is no need for any manual discharging.

 

[cpedw]

It would be useful if the Eprop battery had a simple charge indicator so you can tell if you've charged enough. I always charge the battery off the motor.

 

[Bouba]

It would be useful if the Eprop battery had a simple charge indicator so you can tell if you've charged enough. I always charge the battery off the motor.

The Torqeedo battery has a gauge as long as you keep the tiller arm connected…but unfortunately it doesn’t have anyway to discharge it

 

[arcot]

The Torqeedo battery has a gauge as long as you keep the tiller arm connected…but unfortunately it doesn’t have anyway to discharge it

Run motor until it drops charge to 70 percent

 

[Bouba]

If you get the right cable you can slowly discharge the Torqeedo battery by using it to charge your phone

 

[jlavery]

I've observed that our epropulsion battery was fully discharged after a winter in the garage.

 

[jfkal]

60% is fine.

 

[Poey50]

My Torqeedo battery was stored at 60% at a fairly cool temperature for 6 months and the self-discharge was minimal. Don't leave it fully charged if you want a long life. The charging curve for lithium is linear so the length of time from say 30-40% state of charge (SOC) is approximately the same as 70-80%. So do a timed test of your charger to work out time against SOC. My charger delivers 9% SOC per hour so I just set a timer after deciding how much to put in.