Charge all at once or in stages?

I have a 2014 Leaf and was wondering if charging 2 hours on 1 hour off then 2 hours on etc for the charge cycle for the level one charge to keep battery cool may hurt or help the battery.

Heating and cooling is one of the worst things you can do to any electronic component. Regardless this would be a waste of time and of no benefit at all.

I'm at 60,500km on my 2015. No lost bars. I fully charge at work and home. If I'm out and about and need a top up, I charge for only as long as I need.

If you are only charging with a Level 1 trickle charger, it is hard to imagine that you will cause much heating of the battery under most likely conditions. My advice is to just charge the car and drive it. That has served me well in nearly 4 years of LEAF ownership.

You're probably better off just letting the battery cool first and then charging. Since the pack is air cooled but massive and filled with liquid, even an hour might not be enough to really affect the temperature much. For my LEAF I plug it in when I get home but it doesn't start charging until about 3 hours before I leave for work (using the charge timer), giving it the whole night to cool off and "rest". That also helps to make sure it doesn't stay at a high state of charge for long, usually only an hour or so at most. Once at work it's around 80% and at home it's around 50%. Unfortunately I can't charge to 80% or I'd just do that.

With L1 charging the battery shouldn't heat up much since that's so little power going into it. Heat while charging is mostly just an issue for DC fast charging, aka L3 charging, though you should try to avoid charging when the battery is already hot (like 6 temp bars or more).

Dooglas said:

My advice is to just charge the car and drive it.

Click to expand...

Seconded

It takes winter conditions to cool the battery in any measureable time frame. It's not worth even considering. L2 and L1 charging are easy for the battery to handle. Think of it this way, L1 is ~1kWh, L2 is 6.6kWh. The car can draw near to 90kW under full load, often averages 15-20kW of draw. The motor offers 30kW of regen and DC quick charging offers up to 50kWh. I finally used DC quick charging, twice. After driving from home, charged, drove another hour, charged and drove home. Mostly highway driving ~200km. Charged from ~30% SOC both times and the temp gauge went up one bar, with an ambient temperature of 22C. I drive my Leaf hard, there was zero effort to conserve energy and AC was on full.

L1 and L2 are essentially plug in and forget.

I completely disagree with being concerned about leaving the battery at 100% SOC, for two reasons. The first is this only is a legitimate factor if the car is going to sit unused for a significant period of time. I've left my Leaf at 100% SOC for a week, when I had to leave it and work due to snow. When it was at the body shop for three months, it was left at 70%. The second factor is, I want my car ready to go in an emergency. An uncharged car is almost as useless as a unloaded firearm.

You're probably better off just letting the battery cool first and then charging.

Click to expand...

This. Although the other comment about the battery "being filled with liquid" may not be correct...

It takes winter conditions to cool the battery in any measureable time frame.

Click to expand...

This slipped in while I was writing. When it cools off rapidly at night, the pack can cool a bar in a few hours. If you can take advantage of that, do so. If you can't don't agonize over it - especially with L-1 charging.

LeftieBiker said:

You're probably better off just letting the battery cool first and then charging.

Click to expand...

This. Although the other comment about the battery "being filled with liquid" may not be correct...

Click to expand...

The batteries have a liquid electrolyte, so there's a pretty good amount of liquid in there (most batteries use a liquid electrolyte in fact). Though with it being an organic solvent and not water based, the specific heat might be much lower than water so it might not actual contribute much to the overall heat capacity of the battery. This paper, as an example, shows a 20% increase in heat capacity of a single 18650 battery with electrolyte added compared to one without electrolyte (page 952). That's still substantially less than that of pure water, sp the liquid doesn't contribute greatly. I will concede that "filled" is probably the wrong word to use, since the cells are full of liquid but the assembled pack itself doesn't have liquid sloshing around between cells.

The LEAF emergency responders guide also discusses the electrolyte within the battery and it's potential dangers. The liquid electrolyte is actually the primary fire hazard in lithium ion batteries, which is part of the reason that solid state batteries are such a hot research topic right now (and also non-flammable electrolytes, sometimes with overlap between non-flammable and solid-state which would be the holy grail).