Charging to Full?

[aldaris1234]

I have searched around the forum and couldn't find any posts on charging the car to full. I have been told that it is hard on lithium ion batteries to charge them to full and in the past have been advised to stop charging at like 80%.

Is it hard on the battery in the Clarity to charge it to full or is there already a built in buffer by Honda? I have been so far babying it along and manually stopping the charging at 80%. In my normal commute I only put on about 5 miles a day so I don't really need the full capacity. Just trying to figure out if I am wasting my time watching it so closely.

 

[ClarityDoc]

It's believed that the Clarity charging system is limiting us to about 80% (about 14 kWh) of the battery capacity. Which 80% is not known, but it's in Honda's interest to maintain battery life so I defer to their engineers and just charge the thing.

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[PHEV Newbie]

I have searched around the forum and couldn't find any posts on charging the car to full. I have been told that it is hard on lithium ion batteries to charge them to full and in the past have been advised to stop charging at like 80%.

Is it hard on the battery in the Clarity to charge it to full or is there already a built in buffer by Honda? I have been so far babying it along and manually stopping the charging at 80%. In my normal commute I only put on about 5 miles a day so I don't really need the full capacity. Just trying to figure out if I am wasting my time watching it so closely.

No EV/PHEV will allow you to charge to the battery's absolute full charge or deplete to zero because both situations are harmful. All have buffers built in designed by the company. It is pretty well established that keeping your depth of discharge (DoD) as shallow as possible will lengthen battery life. Also, keeping the charge near 50%. For example, charging to 55% and discharging to 45% will provide close to maximum battery life. Of course, that's impractical for most of us. That's why BEV manufacturers suggest 80% charge for everyday driving because most people don't need a full charge on a day to day basis. Another consideration is cell balancing, which occurs at the end of the charge (don't know if the Clarity also does that at the beginning like some BEV/PHEVs). The traction battery is made up of many little battery "cells" and each charges and discharges at slightly different rates. At the end of charging, the battery management system (BMS) will equalize the charge in each cell. That's why it's important to charge to full occasionally so the cells don't get so imbalanced to be harmed. My needs are unusual. I work from home but run multiple in town errands per day so my typical DoD is less than 20% before I recharge. For that reason, I charge to 80% after each run and then a full charge every week or two when I have a particularly busy day. Honda recommends that you charge to full after every drive. In so doing, it minimizes DoD and allows for cell balancing. Although I believe I'm doing what is best for my battery based on my usage (after 1 year, I've lost no range at all!), this is too cumbersome for most people to think about so what Honda is recommending is the right balance for most people.

 

[MNSteve]

Honda recommends that you charge to full after every drive. In so doing, it minimizes DoD and allows for cell balancing. Although I believe I'm doing what is best for my battery based on my usage (after 1 year, I've lost no range at all!), this is too cumbersome for most people to think about so what Honda is recommending is the right balance for most people.

I wish I knew which was more harmful to the battery - discharging to a low charge, or charging to what Honda says is 100%. If I only charge to 80%, there is a greater chance that I will need to dip lower into the battery capacity than I would like. If my trips were more predictable, I might try a more complicated strategy, but for me I think you're right that the Honda recommendation of charge-and-forget is the right balance for me.

 

[Agzand]

I wish I knew which was more harmful to the battery - discharging to a low charge, or charging to what Honda says is 100%. If I only charge to 80%, there is a greater chance that I will need to dip lower into the battery capacity than I would like. If my trips were more predictable, I might try a more complicated strategy, but for me I think you're right that the Honda recommendation of charge-and-forget is the right balance for me.

The user manual recommends charging to full before each drive for battery longevity.

 

[Viking79]

The car runs the main battery in a safe range no matter what you do. Charge how is convenient. Given that this is a PHEV it charges the battery to a very safe level anyway, lower than a BEV would be charged to so you are doubly safe.

Whatever you decide, you need to make sure you charge completely every now and then leaving it on the charger for a while to ensure that the battery cells stay balanced (that they all are at the same charge level). The battery pack is made up of many individual battery cells. If you don't ever charge completely, they can get out of balance (have different charge levels). This is most likely why Honda has the recommendation to charge it fully.

This has been a problem with Elon's recommendation on the Tesla of only charging to 80% (or less), and Bolt EV was recalled because battery balancing wasn't executing correctly causing the car to suddenly shut down with remaining range left. If your battery cells get out of balance the car can suddenly lose power and die even with a good charge level because one of the cells goes dead before the others and triggers it to shut off. It is fine to charge up to only 60 or 70% while traveling, but once in a while leave it on the charger to balance.

The battery management in the car should prevent you from damaging it from too low of a charge, but it might be as above, shuts off the entire pack suddenly. It will also protect from overcharging. My only recommendation with charging is you unplug during an electrical storm unless you have a full house surge protector installed in your service panel (even then you should still unplug, but it should reduce the chances of the car taking damage from a nearby lightning strike). Requires an electrician to install, but something like: https://amzn.to/2CGanDQ, https://amzn.to/2Rq9MhJ.