Overheating Battery Pack
#11
07-04-2008, 10:43 AM
Re: Overheating Battery Pack
I have a 2007 civic now with 27k miles and am the original owner. I live in the DC commuting area and drive 90 miles a day. Since new, the hybrid system works ok when the weather is cool. As soon as the temp gets above say 85, the pack will start to overheat. The charge and boost indicators will not reach to the top and often stop working altogether. I have brought the car to the dealer several times. They claim it is functioning as designed and quote a page in the manual describing a safety feature that protects the batteries when they get too hot. This appears to be true but I still consider it a defect in that the pack should not be that heat sensitive. If the pack gets too hot to operate just from sitting, what is this doing to the life of the batteries?
I can start in the morning and everything works fine. If the car sits outside all day and gets hot in the sun, the trouble starts. After a hot day in the sun, the hybrid system may work for a minute or two but sometimes not at all. Both charge and assist are affected. This can be a problem when trying to go at a light and the car wont get out of its own way. After 15 -20 minutes of driving with the AC on high, it will start to regain function.
On a side note, during summer months my MPG drops to 35 - 36 for a tank because of the batteries and using the AC. Without AC and normal driving I get 38 - 40. The best I have seen for a tank is 42 MPG.
When driving in bumper to bumper traffic in the city with AC on, I often get full discharge of the pack and the car then goes into "constant on" mode.
I was thinking of piping an AC vent directly to the pack for cooling. Anyone have the same issue or a solution other than parking in the shade all summer?
I can start in the morning and everything works fine. If the car sits outside all day and gets hot in the sun, the trouble starts. After a hot day in the sun, the hybrid system may work for a minute or two but sometimes not at all. Both charge and assist are affected. This can be a problem when trying to go at a light and the car wont get out of its own way. After 15 -20 minutes of driving with the AC on high, it will start to regain function.
On a side note, during summer months my MPG drops to 35 - 36 for a tank because of the batteries and using the AC. Without AC and normal driving I get 38 - 40. The best I have seen for a tank is 42 MPG.
When driving in bumper to bumper traffic in the city with AC on, I often get full discharge of the pack and the car then goes into "constant on" mode.
I was thinking of piping an AC vent directly to the pack for cooling. Anyone have the same issue or a solution other than parking in the shade all summer?
If I crank the air up too high and tackle a big hill, then my battery will end up at 1 bar with some serious forced regen. As long as I keep the A/C on Auto @ about 79-80 degrees, and avoid the big hill, I have no problems. Lately I've been cycling it off during any hill climb, and back on after I hit the top. Really helps with FE.
I would suggest: opening a door or two to let out some of the superheated air for a minute or two before entering. Drive for a few minutes with windows down and A/C off - the A/C only pumps out hot air for the first few minutes away. Why waste the battery to get hot air in your face? After that, flip to Auto on a high temp, but cycle off for hills. Beyond that just trying to be sparing with the use of assist. This method works quite nicely for me. Hope it helps your situation. Oftentimes it's not a mechanical problem with the car, but just methods and/or circumstances that can be changed.
#12
07-05-2008, 05:30 PM
Re: Overheating Battery Pack
May I insert a rookie question? I've been running with the AC almost always off (just using low fan and fresh air settings) on my 2008 HCHII, in part to reduce impact on my SOC and in part because I don't like AC much. (I get away with it because we don't have that many hot humid days). So I've not been using the Auto setting much, but is this a bad idea? Am I at risk of overheating the battery? Went back and read ye olde manual but didn't find this point specifically addressed.
Most of my driving is around town, but I also took a 5 hr steady drive up and down the interstate without any ill effect on engine temp (no overheating). Should I change my ways?
thanks
Pcope
Most of my driving is around town, but I also took a 5 hr steady drive up and down the interstate without any ill effect on engine temp (no overheating). Should I change my ways?
thanks
Pcope
#13
07-07-2008, 03:24 PM
Re: Overheating Battery Pack
I have had the issue almost every day this summer. I do have tinted windows and have nothing blocking the rear vents. I also have small hills like on ramps that make it worse.
The owners manual for my 07 has a short blurb about the vents on page 160. This states the IMA system will shut down if it overheats and will work again when it cools.
Page 69 goes into a little more detail. It does not however give the specific temp that the IMA shuts off.
I have taken it to Pohanka Honda in Marlow Heights MD and also to Browns Honda in Glen Burnie MD. Pohanka basically fed me the "its my fault" line and Browns was more politically correct in stating that it was performing as designed.
I still think there is a major design flaw.
The owners manual for my 07 has a short blurb about the vents on page 160. This states the IMA system will shut down if it overheats and will work again when it cools.
Page 69 goes into a little more detail. It does not however give the specific temp that the IMA shuts off.
I have taken it to Pohanka Honda in Marlow Heights MD and also to Browns Honda in Glen Burnie MD. Pohanka basically fed me the "its my fault" line and Browns was more politically correct in stating that it was performing as designed.
I still think there is a major design flaw.
#14
07-07-2008, 07:32 PM
Re: Overheating Battery Pack
...
Page 69 goes into a little more detail. It does not however give the specific temp that the IMA shuts off.
I have taken it to Pohanka Honda in Marlow Heights MD and also to Browns Honda in Glen Burnie MD. Pohanka basically fed me the "its my fault" line and Browns was more politically correct in stating that it was performing as designed.
I still think there is a major design flaw.
Page 69 goes into a little more detail. It does not however give the specific temp that the IMA shuts off.
I have taken it to Pohanka Honda in Marlow Heights MD and also to Browns Honda in Glen Burnie MD. Pohanka basically fed me the "its my fault" line and Browns was more politically correct in stating that it was performing as designed.
I still think there is a major design flaw.
There are several temperature thresholds within the IPU that are responsible to placing the IMA system into managed mode. Contrary to what some folks say, the IMA is never shutdown. Instead, the managed mode is responsible for canceling thermal escalation, which is an overriding requirement needed to protect the components from damage. Under managed mode the Assist and Regen phases will be curtailed and even canceled as required. Also while in this mode the battery pack can be placed in what is often termed as an instrumented re-initialization mode.
Here are the temperatures to watch for:
MCM - thermal upper limit is 100C (212F)
NiMH battery modules - upper limit is 90C (194F)
DC-DC - upper limit at 215C (419F)
As you can see, any of these threshold temperatures can place place the entire IPU into thermal management mode... so it follows that if you want to avoid the dreaded management mode you should follow the advice we've been giving to HCH-II owners for the better part of the last two years: "Use your AC wisely and you'll do OK. Use it incorrectly or not at all and the result is often unavoidable.
Cheers;
MSantos
#15
07-07-2008, 09:06 PM
Re: Overheating Battery Pack
So how does one see those temps? Are there X-gauges that will let a Scan Gauge owner see those thresholds, or do you need a real diagnostic tool? I don't think I'm having a problem with over-heating the batteries with temps here, but I'm getting recalibration events every other day now and I would like to understand what is causing them...
#16
07-07-2008, 09:34 PM
Re: Overheating Battery Pack
Those and other temps are streamed onto the CAN bus but Ron at Linear Logic appears to be having some issues reading them for eventual integration into the XGauge.
The HDS is the preferred (and only) tool that to the best of my recollection can "display" those values.
However unsettling, those "re-calibrations" are somewhat common in warmer days and you do not need extreme ambient temps to experience them. On this same account, the thing to remember is that the temperatures inside the IPU enclosure is always higher than the temperature inside the passenger cabin. And likewise, the temperatures inside the modules I mentioned are higher than that of the IPU's by a good order of magnitude.
BTW, did you have a chance of taking your car in for a check-up yet?
Cheers;
MSantos
The HDS is the preferred (and only) tool that to the best of my recollection can "display" those values.
However unsettling, those "re-calibrations" are somewhat common in warmer days and you do not need extreme ambient temps to experience them. On this same account, the thing to remember is that the temperatures inside the IPU enclosure is always higher than the temperature inside the passenger cabin. And likewise, the temperatures inside the modules I mentioned are higher than that of the IPU's by a good order of magnitude.
BTW, did you have a chance of taking your car in for a check-up yet?
Cheers;
MSantos
Last edited by msantos; 07-07-2008 at 09:38 PM.
#17
07-08-2008, 10:46 AM
Re: Overheating Battery Pack
Indeed, the IPU thermal management is performing as designed.
As you can see, any of these threshold temperatures can place place the entire IPU into thermal management mode... so it follows that if you want to avoid the dreaded management mode you should follow the advice we've been giving to HCH-II owners for the better part of the last two years: "Use your AC wisely and you'll do OK. Use it incorrectly or not at all and the result is often unavoidable.
Cheers;
MSantos
As you can see, any of these threshold temperatures can place place the entire IPU into thermal management mode... so it follows that if you want to avoid the dreaded management mode you should follow the advice we've been giving to HCH-II owners for the better part of the last two years: "Use your AC wisely and you'll do OK. Use it incorrectly or not at all and the result is often unavoidable.
Cheers;
MSantos
But in keeping with the idea that 'there are no dumb questions' (even though we all know there are), I still would welcome some input. Under temperate conditions, when the passenger cabin remains comfortable, is there still a risk of overheating the battery pack if I'm driving with the AC off? I've been avoiding using the Auto function, as I prefer to control air flow and temp manually. But I've always driven older manual transmission cars in which this was the only option, so I realize that I may be naive. Should I generally use the Auto function under warmer conditions, regardless of whether I want AC?
thanks, Philip
#18
07-08-2008, 11:44 AM
Re: Overheating Battery Pack
Very good question Philip.
Under "temperate conditions" the IPU fan should not need any assistance from additional active cooling from the AC at all. However, the IPU temperature can still rise on the account of heavier usage duty for a combination of IMA specific components.
For instance heavier driving consisting of frequent regen and assists will cause the BCM(regen+assist-> some heat), the battery pack modules(Regen->heat), and the MCM (assist->heat) to generate significantly more heat. Running a lot of 12V accessories, or that awesome sounding audio amp, or those cool looking fog or DRL lights will also cause the DC-DC to also produce extra heat. Heck, even the AC driver produces a bit of heat too especially when forced to work harder.
As you can see, depending on how one uses and drives the car there may be occasions where IPU enclosure will really warm-up and theoretically, a bit of AC could help as well.
But, I suspect that AC should only be used when the higher ambient temps start making the IPU's job of thermally managing itself harder. For the sake of simplicity, I use my own comfort level as an indicator of whether to use the AC or not because that is an implicit and "well reasoned" design consideration. In other words, if moderate and strategic AC use is good for the occupants then it is also helping the IPU.
Cheers;
MSantos
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