care for older battery

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Sep 15, 2022
Greetings, new owner of a 2013 FFE here. ~86K miles, driving range mixed is 55 to 65 miles. Commute is 30 miles round trip. Currently I'm limited to home charging at 120v and public chargers, but I was wondering what the best charging scenario might be with this older battery to prolong its life as I will soon be looking at being able to charge @ 240v at home.

I'd like to be able to control the charge level and timing so will be looking at a 240v charger with those features (recommendations gladly accepted!). We're on a California PG&E TOU rate plan which is 3-tier: .43, .41, and .25 (Winter rates), and I have been waiting until midnight (or close to it) to plug in the car, letting it charge until "full", until around 7AM (full being a Guess-O-Meter between 68 to 72 miles). Is this wise, to do a full charge daily? I haven't yet looked under the hood with FORScan, and frankly I don't know what I'd look for anyway. The car runs perfectly, no gremlins, and charging is even and consistent, from reading our hourly utility account usage graphs over the last 3 weeks since purchase.

Grateful for any sharing of FFE wisdom!
Level 2 chargers have no way to monitor charge level, they can run for some programmed time or until the battery is full, that's it.

Battery wear/longevity is impacted by aggressive discharge FAR more significantly than by L2 charging. Under a hard acceleration, the battery can be pushing more than 150A and driving 60mph is pulling 2-3x as much power as full speed L2 charging.

The period of constant voltage charging for these is actually very brief, so there's not much to be gained by stopping at a lower state of charge. Especially with L2 rather than fast charging.

Just keep it plugged in and let it top up when off peak rates kick in. I know the ChargePoint home chargers can be configured to delay charging until the cheapest time of day based on your plan, but they're not the only ones.
Not to be a Debbie downer but I hope you didn't pay much for it. You are out of warranty and if your battery has a problem it is a throwaway car. FYI the most common failure method is cells swelling which results in coolant connections in the battery being pulled apart and flooding the battery with coolant. Keep an eye on the coolant level in your coolant reservoir. If it is down and you don't see an obvious leak under the car somewhere, that could be bad news that your battery is flooding but it hasn't thrown an error yet.

That said keep it plugged in to L2. The battery TMS is only active when the car is on or plugged in to L2. Although I have seen some reports of battery cooling function on L1.

100% charge is actually 90% SOC so keeping it plugged in doesn't hurt battery longevity. although 80% would be slightly better for the battery but with this small of a battery then you may not have the range you need.

A quick way to measure your usable battery capacity is to charge up all the way and then turn on the enhanced trip meter which shows kWh used. then when the battery is low, say 10% (there is a screen in Sync that shows battery%) you can calculate your usable capacity by using a little math. ie. if you use 12kWh and have 10% battery left, it is simply 12kWh/0.9 = 13.33kWh usable. (0.9 is because you've used 90% of your battery). I'm guessing you should have about 15 ish kWh usable. Try to avoid running the battery all the way down as that is really hard on it and not good for longevity.
Not sure if it differs on the smaller pack - since I didn't have the scan gauge then - but 100% on the larger battery reads as 95% SoC on the pack. 0% on the meter is 5% SoC and the 1kWh emergency reserve goes below that, taking it down to 2.x or 3.x% (been a while since I got down that far)

Also, I've noticed that even here in AZ over the summer, once the battery finished charging and went below the thermal cut, cooling never seems to turn back on again if it heat soaks after that. Not sure if I have something wrong or if that's the norm. At this point in the year, I'm guessing no one else would be able to really test that.

Regardless, keeping it on L2 is at worst doing nothing wrong and otherwise doing good things for the system.

Folks have talked about putting a drip sensor in the battery case - might be worth looking into since monitoring the reservoir is a pain and by the time you see a change, the leak has already been going on a while.

Catch it early enough and you could conceivably save most of the pack.
Thank you for the several perspectives.

The car wasn't cheap, but if I can get reliable use for 4 years I'll be content. The price was equivalent to (relatively low) early-COVID CA prices before the 30 to 40% increase that paralleled the economic recovery & gas price inflation.

The charge time is long enough @ L1 that it doesn't seem that much charging cooling is necessary, and I'm doing this during midnight to mid-morning (at the latest) in a region that's relatively mild (San Luis Obispo, CA).

I do typically use the trip meter, but it doesn't provide total kWh used, just an average of power use per mile at each leg (start/stop, on/off). Is there a way to enable cumulative kWh "consumed" data (per trip, or better, between charges) from the touchscreen settings? Or is this only a FORScan data point?

If I were to install a leak sensor at the battery pack, would this be necessary at each pack, or is one more likely to leak that the other? It there a post detailing this installation (keywords for a search should be sufficient)? I can see that this would be much more effective than monitoring the coolant level, but I'm unsure if it would ultimately make any difference. Could a small leak caught in time actually prevent the loss of a battery pack? !!

Again, many thanks for the responses!
kWh data on the trip meters does not involve ForScan. Not sure if there are different "views" that can be chosen but it's definitely there for me.

No process on the leak sensor. It's something that's been discussed, don't think anyone has taken that plunge.
To get kWh on your trip meter you have to turn on "Enhanced trip meter" It is there in the menus for the left screen you just have to find it and enable it.
From what I've read, the leaking happens on the upper battery...however, I think I read recently that someone had issue with the lower battery as well. I've heard, not seen, that there are 2 plugs on the bottom of the upper / trunk battery back and if those were removed, then you could visually just check if you see a puddle at the back of the car.
triangles said:
To get kWh on your trip meter you have to turn on "Enhanced trip meter" It is there in the menus for the left screen you just have to find it and enable it.

Thank you, I found it there. :)