Gen 3 Insight Forum banner

1 - 15 of 15 Posts

·
Registered
Joined
·
158 Posts
Discussion Starter #1
Are we really warming up the combustion engine? Warming up the cabin? Or are we warming up the batteries under the back seat?

It took me a while to notice, but there is a battery compartment vent in the middle just under the back seat. And if you put your hand in front of it while the car is warming up, you can feel air moving, so I guess there is some sort of fan working to circulate air (?). My understanding is that the batteries need to be within a certain temperature range to get optimum charge/discharge capability. Probably much better for battery health, as well.

So, if we don't drive in a "normal" cabin temperature, does the battery ever come into the optimal operating range? Maybe there is some climate control feeding the battery "controlled" temperature air under the center hump??? But driving around in a winter coat just to save some MPG seems like the wrong way to go. Again, I just reset my trip counter after warm up. The engine has to run anyway, so bleeding off some heat should be free. You can recirculate air in the cabin, but the windows tend to fog. You take the hit in winter either way, so I say reset the counter once everything is warm, then calculate the mileage. My "A" Counter auto-reset is set to tank refill, and my "B" Counter auto-reset is set to engine start. I usually don't have to reset after start unless the warm up period was extensive (single digits or teens).

Phil
 

·
Super Moderator
Joined
·
2,690 Posts
Are we really warming up the combustion engine? Warming up the cabin? Or are we warming up the batteries under the back seat?

It took me a while to notice, but there is a battery compartment vent in the middle just under the back seat. And if you put your hand in front of it while the car is warming up, you can feel air moving, so I guess there is some sort of fan working to circulate air (?). My understanding is that the batteries need to be within a certain temperature range to get optimum charge/discharge capability. Probably much better for battery health, as well.

So, if we don't drive in a "normal" cabin temperature, does the battery ever come into the optimal operating range? Maybe there is some climate control feeding the battery "controlled" temperature air under the center hump??? But driving around in a winter coat just to save some MPG seems like the wrong way to go. Again, I just reset my trip counter after warm up. The engine has to run anyway, so bleeding off some heat should be free. You can recirculate air in the cabin, but the windows tend to fog. You take the hit in winter either way, so I say reset the counter once everything is warm, then calculate the mileage. My "A" Counter auto-reset is set to tank refill, and my "B" Counter auto-reset is set to engine start. I usually don't have to reset after start unless the warm up period was extensive (single digits or teens).

Phil
I think the battery heats up by itself as it is being charged/discharged. The vent in the rear middle seat sucks in air to cool the battery down. I have attached a diagram of the accord hybrid ipu. Honda has a R&D website where you can download technical papers about the hybrid system. https://www.hondarandd.jp/point.php?pid=1287&lang=en
 

Attachments

·
Super Moderator
Joined
·
4,074 Posts
It took me a while to notice, but there is a battery compartment vent in the middle just under the back seat. And if you put your hand in front of it while the car is warming up, you can feel air moving, so I guess there is some sort of fan working to circulate air (?). My understanding is that the batteries need to be within a certain temperature range to get optimum charge/discharge capability. Probably much better for battery health, as well.

So, if we don't drive in a "normal" cabin temperature, does the battery ever come into the optimal operating range? Maybe there is some climate control feeding the battery "controlled" temperature air under the center hump??? But driving around in a winter coat just to save some MPG seems like the wrong way to go. Again, I just reset my trip counter after warm up. The engine has to run anyway, so bleeding off some heat should be free. You can recirculate air in the cabin, but the windows tend to fog. You take the hit in winter either way, so I say reset the counter once everything is warm, then calculate the mileage. My "A" Counter auto-reset is set to tank refill, and my "B" Counter auto-reset is set to engine start. I usually don't have to reset after start unless the warm up period was extensive (single digits or teens).

Phil
Here are a few notes from the manual on high voltage battery and temperature:
  • Functionally, the high voltage battery works in temperatures as low as -22F, and stops working at -40F (p112). In -22F weather, the car 'instructs' you to warm up the interior and/or high voltage battery before you can drive.
  • Changes in interior temperature affects the high voltage battery's relative charging capacity. The number of battery charge indicators may increase/decrease, even if the actual amount of charge remains the same (p129).
  • When the high voltage battery temperature is low, regenerative braking becomes less effective, and it make take longer than normal for the vehicle to start moving (p457).
  • Extreme high temperatures affect battery life, and can be minimized by parking the vehicle in shade during summer (p477).
"Battery University" is an interesting resource for additional information on Li Ion high voltage battery optimal charge/discharge temperature and how to prolong its life. Generally, maintaining battery temperature between -10C to 50C (14F to 122F) helps high voltage battery health and life span, and this range is very manageable.
  • The driving range is calculated at ambient temperature. Cold temperatures reduce the available mileage. This loss is caused by heating the cabin electrically and by the slowing of the battery’s electrochemical reaction, which reduces the capacity while cold.
  • All batteries achieve optimum service life if used at 20°C (68°F) or slightly below. If, for example, a battery operates at 30°C (86°F) instead of a more moderate lower room temperature, the cycle life is reduced by 20 percent. At 40°C (104°F), the loss jumps to a whopping 40 percent, and if charged and discharged at 45°C (113°F), the cycle life is only half of what can be expected if used at 20°C (68°F).
 

·
Registered
Joined
·
158 Posts
Discussion Starter #4
I think the battery heats up by itself as it is being charged/discharged. The vent in the rear middle seat sucks in air to cool the battery down. I have attached a diagram of the accord hybrid ipu. Honda has a R&D website where you can download technical papers about the hybrid system. https://www.hondarandd.jp/point.php?pid=1287&lang=en
Good info.

Thanks, andrew28 :smile:

More responses to read...catching up...

Phil
 

·
Registered
Joined
·
158 Posts
Discussion Starter #5
Here are a few notes from the manual on high voltage battery and temperature:
  • Functionally, the high voltage battery works in temperatures as low as -22F, and stops working at -40F (p112). In -22F weather, the car 'instructs' you to warm up the interior and/or high voltage battery before you can drive.
  • Changes in interior temperature affects the high voltage battery's relative charging capacity. The number of battery charge indicators may increase/decrease, even if the actual amount of charge remains the same (p129).
  • When the high voltage battery temperature is low, regenerative braking becomes less effective, and it make take longer than normal for the vehicle to start moving (p457).
  • Extreme high temperatures affect battery life, and can be minimized by parking the vehicle in shade during summer (p477).
"Battery University" is an interesting resource for additional information on Li Ion high voltage battery optimal charge/discharge temperature and [url="https://batteryuniversity.com/index.php/learn/article/how_to_prolong_lithium_based_batteries']how to prolong its life[/url]. Generally, maintaining battery temperature
between -10C to 50C (14F to 122F) helps high voltage battery health and life span, and this range is very manageable.
  • The driving range is calculated at ambient temperature. Cold temperatures reduce the available mileage. This loss is caused by heating the cabin electrically and by the slowing of the battery’s electrochemical reaction, which reduces the capacity while cold.
  • All batteries achieve optimum service life if used at 20°C (68°F) or slightly below. If, for example, a battery operates at 30°C (86°F) instead of a more moderate lower room temperature, the cycle life is reduced by 20 percent. At 40°C (104°F), the loss jumps to a whopping 40 percent, and if charged and discharged at 45°C (113°F), the cycle life is only half of what can be expected if used at 20°C (68°F).
Thank you, Insightfully, for that awesome information. Just as I thought, battery temperature does matter, although I don't "think" the 3G Insight heats the cabin with electric, as the combustion engine stays on while the car is heating.

Phil
 

·
Registered
Joined
·
3 Posts
Purchased my Honda Insight Touring yesterday. I'm not sure I've ever been this excited to own a vehicle. This is my first hybrid and I'm loving it!

One question - the rear seat has what looks like a vent in the middle area. Any idea of its purpose?

Thanks,
Tazo
 

·
Super Moderator
Joined
·
4,074 Posts

·
Super Moderator
Joined
·
1,232 Posts
Purchased my Honda Insight Touring yesterday. I'm not sure I've ever been this excited to own a vehicle. This is my first hybrid and I'm loving it!

One question - the rear seat has what looks like a vent in the middle area. Any idea of its purpose?

Thanks,
Tazo
The vent is for air circulation for the high-voltage battery. If you put your hand in front of it while the car is running, you may feel airflow.

I'm 19K miles and almost a year into my Insight, and I'm still excited every time I get in it!

Congratulations on your new Touring!
 

·
Registered
Joined
·
141 Posts
Do we know where is the air outlet in our Insights? There is none under the rear seats. Is that through the rear windshield? Or is it vented outside?
i believe the air outlet for the high voltage battery is in the underside of the car. Someone posted months earlier that they had their Insight parked maybe at the beginning of a steep driveway at the street. During heavy rain that built up in the curb/gutter area, water was able to enter the back seat thru the battery vent outlet and get under the back seat and onto the rear floor. I would like to think Honda put some thought into this and have the vent up as high as they could for normal driving/parked conditions, but this is still sad that the venting area availability is obviously limited to the undercarriage design.
 

·
Super Moderator
Joined
·
2,690 Posts



The diagrams is for the 2018 Accord Hybrid but the Insight should be similar.
 

·
Registered
Joined
·
328 Posts
The high voltage battery exhausts to the side of both sides of the rear seats (the large plastic sides next to the seats that leads into the bottom of the rear door jam). I wish I still had that diagram but I lost it somewhere.
 

·
Registered
Joined
·
296 Posts
The high voltage battery exhausts to the side of both sides of the rear seats (the large plastic sides next to the seats that leads into the bottom of the rear door jam). I wish I still had that diagram but I lost it somewhere.
I see the large plastic thing but I don't see any exhaust grille?
 

Attachments

·
Super Moderator
Joined
·
4,074 Posts
I see the large plastic thing but I don't see any exhaust grille?
There's an input grille but not an exhaust grille. Per the diagram andrew28 re-shared in post 10, the outlet is on the rear passenger side below the seat, powered by cooling fan and all contained below the rear seats. There's a part-list-type diagram of the Insight's HV battery configuration in the following thread - https://www.gen3insight.com/forum/28602-post71.html
 

·
Registered
Joined
·
328 Posts
I will take an educated guess that the exhaust destination goes right back into the cabin since the heat generated is not enough to be concerned with, so they throw it into the cabin through these plastic coverings that dissipate the exhaust all along the door areas.. It is probably cheaper than constructing a new conduit for the exhaust to flow through.
 

·
Registered
Joined
·
836 Posts
I will take an educated guess that the exhaust destination goes right back into the cabin since the heat generated is not enough to be concerned with, so they throw it into the cabin through these plastic coverings that dissipate the exhaust all along the door areas.. It is probably cheaper than constructing a new conduit for the exhaust to flow through.
I'll check next time it's on a lift, but I'd be willing to bet it just vents to atmosphere. In the event of thermal run away, the venting gasses can surpass 1000*C (average is ~500*C according to Nasa testing). The only reason why I think they wouldn't want to vent into the cabin is the potential liability if a battery ever went through a thermal runaway event.
 
  • Like
Reactions: LowRider
1 - 15 of 15 Posts
Top