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Discussion Starter #1
Hello,

What would be the best tips to prepare the car for a 1-month outdoor parking? Temperatures should be in the 80s 90s.

I'm mostly thinking about the battery (my obsession) and I will try to leave it a 5-6 bars if I can, does that sound right? What else should I be doing?

Thanks!
 

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1-month doesn't sound that long, relative to Honda's recommendation for running the car for 30 minutes every 3 months...

When I know I won't be driving the Insight for a while, I get the HV battery level to 6-8 bars before parking. The main risk/concern is that the car won't start if the HV battery discharges too far while parked. The longest I've gone between drives is ~1 month, and at start-up, the HV battery level is the same as I've left it.

Suggestions from the HV Battery Health and 12V Trickle Charge threads come to mind:
  • Exercise the hamsters on a 10+ mile highway drive, and use sport mode before parking the car, to build HV battery charge before extended shut down.
  • AGM-compatible trickle charger for 12V battery.
  • Toyota Hybrid tips for extended storage (very similar to Honda's tips)
 

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There should be no draw on the HV battery when the vehicle is off. Those loud clicks when turning the car on from the back are the system main relays turning on. There is no reason besides overall lifespan to make sure the HV pack is between 50-80% charged if leaving parked, which i'm guessing the battery level display when empty is probably still 50-60% actual HV state of charge.

On the other hand the 12v battery has a large draw on the system from the smart key transponders that are constantly looking for someone to walk up to the vehicle. There should be a short pin in the engine bay fuse box to cut the non-essential circuits, normally used for factory transport. The 12v battery negative can also be disconnected which is the best method, its a little tight to get the terminal off and away from the battery but the console panel comes off very easy. There will be warning lights after reconnecting the battery but they all go out after the car does its self calibration driving normally.

You can try turning off all accessories, hvac, auto lights, dome light, etc when leaving it to give the car the best chance to start back up, then try to start after one month but I would bet the small 12v battery will be dead by then, it will be close though. The issue here is that with agm batteries even going dead once can kill the batteries health and it will fail a battery test even after fully recharging it.
 

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Discussion Starter #4
There should be no draw on the HV battery when the vehicle is off. Those loud clicks when turning the car on from the back are the system main relays turning on. There is no reason besides overall lifespan to make sure the HV pack is between 50-80% charged if leaving parked, which i'm guessing the battery level display when empty is probably still 50-60% actual HV state of charge.

On the other hand the 12v battery has a large draw on the system from the smart key transponders that are constantly looking for someone to walk up to the vehicle. There should be a short pin in the engine bay fuse box to cut the non-essential circuits, normally used for factory transport. The 12v battery negative can also be disconnected which is the best method, its a little tight to get the terminal off and away from the battery but the console panel comes off very easy. There will be warning lights after reconnecting the battery but they all go out after the car does its self calibration driving normally.

You can try turning off all accessories, hvac, auto lights, dome light, etc when leaving it to give the car the best chance to start back up, then try to start after one month but I would bet the small 12v battery will be dead by then, it will be close though. The issue here is that with agm batteries even going dead once can kill the batteries health and it will fail a battery test even after fully recharging it.
Thank you for the infos. I would be surprised if the car doesn't start after a month in the summer. Last winter, I left for two weeks, temperatures were probably around 20˜F and the car started right away.
 

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Discussion Starter #5
Could it be bad to park it at above 90%? With potentially 90s weather? It's typically not great for phones so I suppose it's the same for cars? I think phones are shipped/stored at about 60%...
 

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Could it be bad to park it at above 90%? With potentially 90s weather? It's typically not great for phones so I suppose it's the same for cars? I think phones are shipped/stored at about 60%...
I like information from Battery University for technical information on Lithium Ion batteries. Their How to Prolong Lithium-based Batteries article discusses the relative impact of cycling, heat, and state of charge (SoC). In particular:

"Lithium-ion suffers from stress when exposed to heat, so does keeping a cell at a high charge voltage. A battery dwelling above 30°C (86°F) is considered elevated temperature and for most Li-ion a voltage above 4.10V/cell is deemed as high voltage. Exposing the battery to high temperature and dwelling in a full state-of-charge for an extended time can be more stressful than cycling."

Time/duration left in heat is also a factor though. Extended parking of 1 month (per original post mention) is relatively short in the data/impact analyzed. For a battery left at 100% SoC, the biggest capacity degradation (-35%) occurs at 104 F (40 C) temperatures for 1 year, or 140 F (60 C) for 3 months. Capacity degradation still occurs at low SoC and high temperatures, but to a somewhat lesser extent after 1 year (-25%).

For additional technical info, there's another detailed Battery University article on How to Store Batteries and some discussion in the forum on heat / battery charge and EV mode.
 

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I like information from Battery University for technical information on Lithium Ion batteries. Their How to Prolong Lithium-based Batteries article discusses the relative impact of cycling, heat, and state of charge (SoC). In particular:

"Lithium-ion suffers from stress when exposed to heat, so does keeping a cell at a high charge voltage. A battery dwelling above 30°C (86°F) is considered elevated temperature and for most Li-ion a voltage above 4.10V/cell is deemed as high voltage. Exposing the battery to high temperature and dwelling in a full state-of-charge for an extended time can be more stressful than cycling."

Time/duration left in heat is also a factor though. Extended parking of 1 month (per original post mention) is relatively short in the data/impact analyzed. For a battery left at 100% SoC, the biggest capacity degradation (-35%) occurs at 104 F (40 C) temperatures for 1 year, or 140 F (60 C) for 3 months. Capacity degradation still occurs at low SoC and high temperatures, but to a somewhat lesser extent after 1 year (-25%).

For additional technical info, there's another detailed Battery University article on How to Store Batteries and some discussion in the forum on heat / battery charge and EV mode.
Excellent, thank you very much. High voltage is, according to your link, starting at 85%. Second link says "Finding the exact 40–50 percent SoC level to store Li-ion is not that important.". Look like around 50-60% should be a happy medium!
 

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Update: started with no issues after a month. I had parked it with something like 7 bars and it was left with maybe 6 bars but not 100% sure (jet lagged!). Brakes are a little rough but nothing crazy.
 
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