Hybrid battery running down overnight

<div class='quotetop'>QUOTE(ScottR @ Jul 24 2006, 03:21 PM) [snapback]291528[/snapback]</div>

I think it's the smart key and the air conditioning compressor starting up that causes this..... I've noticed it a couple of times as well.

 

It's definately not the SKS - the hybrid battery pack is disconnected from the car when it's off. The SKS draws it's power from the 12V battery. I doubt that a compressor could cause this in the few seconds during power up before the MFD comes on.

rather, i would suggest that it might be a difference in temperatures that causes it. The hybrid battery is fairly temperature dependant, so if the car is very hot when you leave it in the evening (say a 5-10 min drive home from work after sitting in the sun all day), then rather cool in the morning, i think you could see the readings on the battery differ.

 

I have not seen drops unless it was over 7-10 days and they have been small. Are you sure you are turning the car off? Dumb question. I am not sure what else would cause this.

 

Where are you keeping your SKS remotes in relationship to your car? I believe I have read that if they are too close to the vehicle then it does drain your battery.

I park my car outside and the temps have varied from 40's overnight to 80's overnight. I have not seen any noticeable changes in the charge left on the battery.

As far as not ever getting a "full" battery graph, that is not a big deal. The actual "desired" charge is somewhere in the middle. That is where the car like to be and will not try to charge the batteries until they are totally full. Most of the time you get a "full" battery is when you come down a long hill, or use the brakes for a period of time. It is fun to have a higher charge, especially when using forced EV mode, or Stealth, but not at all necessary.

 

I feel like I have seen it go both ways - which suggests that it may be a temperature issue.

 

<div class='quotetop'>QUOTE(ScottR @ Jul 24 2006, 05:16 PM) [snapback]291675[/snapback]</div>

Remember that the bars don't represent the entire charge range of the HV battery - rather, they represent the usable charge range, which is considerably smaller. Also note that the gague is non-linear, which means that you will only rarely see full or no charge (especially because the computer tries to keep the battery as near to the halfway mark as is possible).

I have never seen more than six bars in my Prius.

 

<div class='quotetop'>QUOTE(mssmith95 @ Jul 24 2006, 10:05 PM) [snapback]291787[/snapback]</div>

Yes, but it's the small 12V battery that drains, not the hybrid battery (which is disconnected from the system whn turned off).

<div class='quotetop'>QUOTE(bsoft @ Jul 25 2006, 02:33 AM) [snapback]291862[/snapback]</div>

Are you sure it's as near the halfway mark? for me, it seems that the car tries to keep charged up to the Blue/green barrier. but i know you're right about the range thing - i believe the range on the MFD is 40%-80% (correct me if i'm wrong), and there have been posts with pictures showing the rough percentage associated with each bar, and it is non-linear.

It's really tough to tell if the temperatures can effect the charge that drastically without doing some more concrete studies (ie record the temperature and the reading in the evening, then again in the morning over a period of weeks). I can say, however, that temperature definately does effect the usable amount of charge on normal batteries. To provie it to yourself, next winter take a pair of half dead AA's outside in your walkman and let them sit for a few hours... try to play, and if they don't act dead then they will soon enough... bring them inside and warm them up, suddenly it'll play again. (i've shown this time and time again when camping in Boy Scouts during the winter)

 

<div class='quotetop'>QUOTE(Lil Mo @ Jul 24 2006, 11:26 PM) [snapback]291800[/snapback]</div>

It could not be the temperature change. Remember that the prius determines State Of Charge by "columb counting." So if no current has moved, then the known SOC could not have changed.

 

I haven't noticed a drop in battery level overnight, but with my memory I would probably need to leave myself a note on the dash to be able to compare.

I do occasionally see the full battery indication, with all bars and in the color green. I live and work in Honolulu so don't regularly travel over the Koolau's to the windward side of Oahu, but experience the full charge every time I do, regardless of the route. It's the looooong downhill.

 

I try to use up as much battery I can on the last strech home as I know the engine will run for 5 minutes next morning. I normally try to leave it towards the low mark (but still blue). Many morning when I start the car it has dropped a bar (now purple). I've taken this to be the temp. difference.

The car running 5 minutes will still fill it up to 6-7 bars (blue) while warming up and I've seen to real difference is MPG for the first 5 minutes doing it.

 

<div class='quotetop'>QUOTE(jmann @ Jul 26 2006, 03:15 AM) [snapback]292343[/snapback]</div>

This seems an unwarranted assertion. Yes, it measures current flow to and from the battery, but it also monitors the temperature. I see no reason why it couldn't change its idea of "usable capacity" as the temperature changes, which could in turn change its "percentage charge" figure.

However, personally, I've never noticed it starting with a different charge to when it was parked. It often loses a bar very rapidly, during stage 1, mind.

 

I've noticed the display is almost always lower in the morning too.

I've tried a little experiment, but don't have enough trial points to form a conclusion. I THINK that if I leave the radio, blower and lights on when I turn off the car, then the battery bars are lower in the morning.

On mornings after I turn everything in the car off BEFORE I power down, then the bars seem to be more consistent.

This is just a theory. Since all of these things are technically "off" when after you get out of the car (lights stay on until the car door is opened), I can't imagine that they really do a lot of draining.

The other thing that MIGHT be causing this is simple timing. I've noticed that battery level bars are not an immediate indicator of battery charge. For example, if I get a long re-gen phase the battery indicator takes a minute or so to report an increased charge. My last 100 feet or more into my garage are almost always on battery, so it is possible that the display just hasn't caught up with reality until the power on the next morning.

I like the temperature theory to, but my morning temps are between 70 and 85 and morning temps don't seem to coincide with the battery level overnight. Like I said I don't have a ton of data points, but that's my general impression.

 

the SOC indicator recalibrates every time you start the car, that might do it.

 

i notice that the HV Batt ecu or that ECU by the battery has some sort of a delay when charge levels change, for example, if you disconnect your 12 volt battery and wait 5 minutes and connect it you will have 5 bars showing up on the MFD even though you may have just under 2 bars. it takes a whiel for the battery ecu to calibrate or something, i have noticed this a lot on the newer prius's.

 

<_< Most often, my SOC indication is HIGHER (more bars) on a morning start after being parked in the garage all night. So... add that to the confusion. The SOC is almost always LOWER (fewer bars) when parked in a *HOT* (read 100º plus degrees) during work hours.

Sounds like a main battery temperature issue to me.

 

old thread, not sure anyone would read it.