HV Battery Self-discharge Rate - GreenHybrid - Hybrid Cars


Reply
 
 
 
LinkBack Thread Tools Search this Thread
  #1  
Old 08-08-2010, 09:02 AM
gpsman1's Avatar
Hybrid and Ethanol Expert
Thread Starter
 
Join Date: Mar 2005
Location: All over the Central U.S.
Posts: 3,589
Exclamation HV Battery Self-discharge Rate

I got back from a 2 week trip.
I was careful to leave my FEH with a high charge when I parked.

I parked with exactly 52.7% on the Scangauge SOC meter.
I was gone 14 days.
I returned and the SOC was 45.7% before starting.

Exactly 7% charge lost in 14 days. ( or 0.5% per day )

It has been consistent like this the past couple of years.
I never had the ability to check for this the first couple of years.

I'm curious what other people are seeing.
I'm curious if this is calculated, or the FEH "assumes" 0.5% per day.
I'd like to know, how it knows the SOC lost being parked.
It will be interesting to know if this gets worse with age.
My 2005 FEH has about 117,000 miles.
Reply With Quote
  #2  
Old 08-08-2010, 11:51 AM
Imported from Detroit
 
Join Date: Apr 2009
Location: Michigan
Posts: 1,051
Default Re: HV Battery Self-discharge Rate

Since there is no load, there's only one way which you probably won't agree with, voltage.
Reply With Quote
  #3  
Old 08-08-2010, 12:07 PM
gpsman1's Avatar
Hybrid and Ethanol Expert
Thread Starter
 
Join Date: Mar 2005
Location: All over the Central U.S.
Posts: 3,589
Default Re: HV Battery Self-discharge Rate

No load voltage at 52.7% = 339v
No load voltage at 45.7% two weeks later, 325v.

14v/250 cells = 0.05v per cell.

Does 0.05v = 7% charge?
Or did Ford lab test these 1000 times and find they average 0.5% loss per day and just use that as a basis?
Reply With Quote
  #4  
Old 08-08-2010, 02:45 PM
Imported from Detroit
 
Join Date: Apr 2009
Location: Michigan
Posts: 1,051
Default Re: HV Battery Self-discharge Rate

Quote:
Originally Posted by gpsman1 View Post
No load voltage at 52.7% = 339v
No load voltage at 45.7% two weeks later, 325v.

14v/250 cells = 0.05v per cell.

Does 0.05v = 7% charge?
Or did Ford lab test these 1000 times and find they average 0.5% loss per day and just use that as a basis?
Who knows "really" how the SOC is calculated! I say voltage, you say it counts days but what about warm days or cold days? Self discharge is less when colder!
Reply With Quote
  #5  
Old 08-08-2010, 06:40 PM
gpsman1's Avatar
Hybrid and Ethanol Expert
Thread Starter
 
Join Date: Mar 2005
Location: All over the Central U.S.
Posts: 3,589
Default Re: HV Battery Self-discharge Rate

I'm not sayin' anything. I'm asking. I'm asking other FEH owners who happen to also have SOC monitoring equipment to reply back with what they see in their own personal vehicles. If everyone reports 0.5% loss per day, that means something. If results are all over the place, that means somthing else.
Your hypothesis is one good one. Now we need more data.
Reply With Quote
  #6  
Old 08-13-2010, 07:35 AM
Active Enthusiast
 
Join Date: Jul 2009
Posts: 67
Default Re: HV Battery Self-discharge Rate

Quote:
Originally Posted by gpsman1 View Post
I'm not sayin' anything. I'm asking. I'm asking other FEH owners who happen to also have SOC monitoring equipment to reply back with what they see in their own personal vehicles. If everyone reports 0.5% loss per day, that means something. If results are all over the place, that means somthing else.
Your hypothesis is one good one. Now we need more data.
The FEH battery is NiMH (made by Panasonic, I believe). Typical NiMH characteristic is self-discharge at a rate of 25% per month. The fact that you lost at only a ~15% per month rate is actually quite good. Note that the 25% per month is for battery only, not including monitoring circuitry built into the pack. However, the self-discharge of NiMH is high enough to completely swamp the monitoring circuitry. This won't be the case for new Li-Ion packs. Li-Ion typical self-discharge rate is very low, <1% per month, but expected monitoring loss is ~3% per month. This is a combination of the individual cell balancing and monitoring circuitry as well as the overall SOC / Temp / etc circuitry built into the pack. But 3% is a lot lower than 15-25%...RayP

Last edited by RayP; 08-13-2010 at 07:40 AM.
Reply With Quote
  #7  
Old 08-20-2010, 12:22 PM
gpsman1's Avatar
Hybrid and Ethanol Expert
Thread Starter
 
Join Date: Mar 2005
Location: All over the Central U.S.
Posts: 3,589
Default Re: HV Battery Self-discharge Rate

Parking my FEH again @ 52.7%. Will see how close the results were to last time.

I've done more and more research into LiION and while they have more energy per pound, they do not seem durable enough for Hybrid or Electric car use. Expected lifespan is 3 years, and 36,000 to 50,000 miles, top end.
Reply With Quote
  #8  
Old 08-20-2010, 04:43 PM
Imported from Detroit
 
Join Date: Apr 2009
Location: Michigan
Posts: 1,051
Default Re: HV Battery Self-discharge Rate

Quote:
Originally Posted by gpsman1 View Post
Parking my FEH again @ 52.7%. Will see how close the results were to last time.

I've done more and more research into LiION and while they have more energy per pound, they do not seem durable enough for Hybrid or Electric car use. Expected lifespan is 3 years, and 36,000 to 50,000 miles, top end.
So, if they aren't any good why are they switching to Li-Ion? They are way easier to charge. I have a 1600mAH 17670 Li-Ion cell in a SureFire U2 Ultra flashlight for over two years without recharging and it still works. I have Li-Ion cells in other custom made LED flashlights with the same results.
Reply With Quote
  #9  
Old 08-20-2010, 05:08 PM
Active Enthusiast
 
Join Date: Jul 2009
Posts: 67
Default Re: HV Battery Self-discharge Rate

Quote:
Originally Posted by gpsman1 View Post
I've done more and more research into LiION and while they have more energy per pound, they do not seem durable enough for Hybrid or Electric car use. Expected lifespan is 3 years, and 36,000 to 50,000 miles, top end.
This is old information. This is pretty much true for LCO and NMC types, but is generally not true for LMO and certainly not for LFP. The Volt will use LMO made by LG, and the Leaf will use LMO made by NEC, and while I personally don't trust their safety, their lifespan and range is way beyond what you are quoting. What I am waiting for is our US manufacturers to get going on volume production of LFP, which is going to revolutionize Lithium batteries. The latest research out of MIT on LiPO4 coatings on LFP crystals makes LFP nearly the perfect battery technology from a shelf life, charge lifetime, and charge rate perspective. Density is pretty good as well, far better than NiMH but still lacking compared with Li-S, Li-Air, etc. But those techs are still way too unsafe for any application, especially EVs.
Reply With Quote
  #10  
Old 08-20-2010, 05:10 PM
Active Enthusiast
 
Join Date: Jul 2009
Posts: 67
Default Re: HV Battery Self-discharge Rate

Quote:
Originally Posted by wptski View Post
So, if they aren't any good why are they switching to Li-Ion? They are way easier to charge. I have a 1600mAH 17670 Li-Ion cell in a SureFire U2 Ultra flashlight for over two years without recharging and it still works. I have Li-Ion cells in other custom made LED flashlights with the same results.
SureFires are great, aren't they? Even the protected cells have a discharge rate of <3% per month, so after 2 years they should still have some life left. Unprotected cells are <<1% but of course they can explode on you if you aren't careful during charging, and are too easy to damage with over-discharging...
Reply With Quote
 
 
Reply

Related Topics
Thread Topic Starter Forum Replies Last Post
SOC Discharge rate guyver76 Ford Escape Hybrid 8 10-19-2012 09:46 AM
IMA Battery diagnosis using discharge-recharge method drozzin Honda Accord Hybrid 0 02-15-2012 04:04 PM
Main battery discharge houseofcharm Honda Accord Hybrid 1 05-16-2010 03:21 PM
Charge/Discharge rate? GordonLightfoot HCH II-Specific Discussions 0 04-27-2009 06:43 AM
Battery Discharge cb450sc Honda Civic Hybrid 3 04-02-2006 07:31 AM


Tags
battery, camry, cars, charging, civic, discharge, discharges, escape, ford, honda, hv, hybrid, nimh, prius, rate, toyota

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -7. The time now is 10:40 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.