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TOPIC: battery voltage check

battery voltage check 9 months 3 weeks ago #84263

What is that red stuff that gets sprayed on the battery terminals?
Can I get rid of it with WD40 and a paper towel?
The only thing I notice about that red stuff is that it attracts
dirt to the terminal connections.

My scangauge2 shows normal voltage on both my 02 civic EX and 06 Civic Hyb as 14.1V during normal operation.
Yesterday, I noticed voltage in the 06 Hybrid was 13.7 cold and fluctuating between 12.3 and 13.3 warm.
I'm not sure if that is still within spec or if the MVCI mvci.service-solutions.com/ would flag it yet,
(dealer tools). The helms states the 12V battery needs a full charge before accessing
the ecm pcm bcm with the modules (HIM / MVCI).
Both my scangauge and base actron are not showing any codes,
but I doubt either has access to the IMA system.

I'm not in a rush to fix anything. Any normal driver would probably not even notice anything different
or wrong about the cars behavior. The mpg still looks normal,
but I'll have to wait a bit before I can double check that with any accuracy.

I would like to start by getting a baseline scan, especially of the IMA systems.
Any recommendations for a scan tool welcome.
I'm slowly reading the helms, which makes me step back and think before I leap.

It's a closed loop system ( according the the scangauge2 ), which goes into open loop when
the engine is, auto off and maybe during deceleration, but I'll have to double check
when, if and for how long, it opens during deceleration.

My hope is that maybe some of this sounds familiar to anyone or yall with IMA
and / or advanced troubleshooting.
I do realize I have a long way to go as a DIYer,
before I get a handle on what is going on with this machine.
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battery voltage check 9 months 3 weeks ago #84274

  • grg8888
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Battery voltage is not a very good indication of anything. If the battery is weak the voltage is usually a bit low but then when you start the engine the alternator will try to overcompensate so then the voltage may be okay, or even a bit high. Also battery voltage is strongly temperature dependent, about 12 millivolts per degree F. So, voltage is not very helpful.

A better test is:

With the engine off, turn on the headlights, high beams too. That is about a 20 to 40 amp draw. Wait 20 minutes or until the headlights are dimming to yellow or orange. Now with a good battery, that 20 minutes should discharge it by about 25%, and it should still be putting out full voltage and the lights should still be near full brightness and color. With a weak battery, it will be nearly completely drained and the lights will be orange or worse.
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battery voltage check 9 months 3 weeks ago #84289

Thanks for the tips. They help me understand better what is actually going on.
I think my emergency brake froze to the drum the other night, so maybe the cold does have
something to do with my voltage being a little lower. The dealer wanted to swap it out
a year ago for $200. I cleaned the terminals had A-Z slow charge it and it came back to 530+ CCA.
I'd already been thinking about the IMA battery back then as well,
but last winter I didn't notice anything unusual.
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battery voltage check 9 months 3 weeks ago #84695

sure enough! now I feel just a bit foolish.

I've been scrambling around reading up on everything I can find related to the electrical
system in this car. And I've found a lot of things I will be following up on.

Well, I pulled the 12V battery out of the car and took it to advanced for a load test. It's rated 290 CCA
and it tested 170 CCA at 71 degrees / 12.57V . Needles to say I got a replacement.

When the replacement is installed ( it's on maintenance charge now ),
it will really be interesting to see how the systems adjusts to the new 12V source.

I'm guessing that the weak battery was a parasitic draw that the DC to DC converter flagged.
Then adjusted by sending more volts to the weak battery up front while taking volts away from the IMA pack in the back.
It's just a theory and I will be trying to learn how to figure out what actually happened.
I was too stubborn to actually check it when mechanic left me those two big red hints on the battery terminals in Oct. :blush:
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battery voltage check 9 months 2 weeks ago #84998

The new battery is in and seems to be working OK. scangauge2 showing an average of 13.5V
There is a 12V battery test for parasitic leak while entering sleep mode,
that I will get to in due course, because I still don't understand all of what's involved.

While looking for reasons why the SOC ( State of Charge ) gauge is misbehaving,
(This morning was the first time in months that the SOC was not at FULL when starting cold in the morning.)
I ran a Diagnostic self test of the B-CAN system ( Self diagnostic Mode 1 ) and the MICU switches ( Self diagnostic Mode 2 ).
MICU == Multiplex Integrated Control System

I have two codes that neither the actron or the scangauge could read.
2968 ( A short in the humidity sensor circuit )
2993 ( A short in the Thermal protector circuit )
The manual says to tackle each code in numeric sequence. ie 2968 first than 2993
The manual heavily favors using the HDS, but I think I can still so at least some preliminary testing without the HDS.

I'm looking at the manual as I typing here and I just found the
climate control - Self-diagnostic functions without HDS
which I'll now attempt.

Last night after I identified the DTC's I took the car for a drive and for climate control I selected circulate instead of the
default fresh and I switched off the A/C which is turned on by default as well.
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battery voltage check 9 months 1 week ago #86049

I spent most of last week reading and testing,
so this post will probably not be in the exact sequence I followed.

I'd taken the car for a few short trips ( less than 25 miles ) last week, while doing the diagnostics
and noticed that the SOC ( State of Charge ) gauge
was both charging and discharging the IMA battery pack faster,
especially when first starting - cold - in the morning.
The SOC would even out and stay charged a bit longer when warm, ( after about 10 miles ).
But the SOC shows recharging to full ( 8 squares ), from empty ( 2 squares )
about twice as fast now ( over the weekend and this week )
as it did before I started running the diagnostic self tests last week.

After doing the initial self test ( grabbing the DTC's ( diagnostic trouble codes ))
and the climate control self test, ( mentioned in post above )
I did the B_CAN self diagnostic again or
cleared the DTC's than ran the diagnostic self test again.
I ran the tests a couple of times to learn how they worked and what they tested for.

After clearing the codes and running the diagnostic again one code cleared
and one code was still in memory.
2968 ( A short in the humidity sensor circuit )

So I pulled the dash covers and disconnected the humidity / interior temperature sensor.

( I actually disconnected all the modules in that section of the dash and removed that center section of the dash )
radio/CD, climate control module, 4 way blinker, humidity/temperature sensor, srs passenger air bag off light
and
the odometer trip, temp / average mpg, dash light dimmer button switches in the other dash cover I had to remove first.

There was some dust and a few small fibers on the humidity / temperature sensor
that I cleaned with air.
Then I reconnected only the climate control module and the humidity /temperature sensor and ran the climate control self test again.
The - 2968 ( A short in the humidity sensor circuit ) - DTC was gone.

( initially I thought I wasn't seeing the entire climate control self test, it seemed a lot shorter than the description in the manual, but I guess that was me not fully understanding the manuals description.)

The difference was that when running the climate control self test,
when the self test finished the CEL would flash five times, indicating a code was still in memory.
At least that is my current understanding of how this thing works ....
CEL = ( the manual calls it the MIL ( Malfunction Indicator Light/Lamp))

I reconnected all the senors, switches and radio/CD, entered the security code than took the car for a 100 mile drive the next day ( yesterday ) and will make a new post in What are you working on? about what happened next ,,,,
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battery voltage check 9 months 1 week ago #86068

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The SOC indicator is a VERY approximate attempt at figuring out the battery charge.

The only REAL and ACCURATE way of figuring out SOC is to use a Hygrometer to measure the density of the battery acid.

The SOC gauge sort of does "dead reckoning", by assuming a certain level of starting charge and integrating the current in and current out and doing its best to estimate how much of the net input charge is sticking to the battery. All based on very approximate guesses and estimates.
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battery voltage check 9 months 1 week ago #86118

  • EricTheCarGuy
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This may be one of those situations where 'if it ain't broke, don't fix it'. The humidity sensor is not a critical component to the engine's operation. In fact, I believe it's only there for the HVAC. In fact, I'd doubt that you'd even know it was bad if you weren't looking. Actually, not knowing the scanner you're using, it could easily be a communication issue. Most DIY scanners don't read body codes.

I could be wrong, but if you're not experiencing any issues, I would recommend you leave well enough alone.

If you're looking to learn. Check out these articles I've written.

www.ericthecarguy.com/faq

Keep us posted.
Stay dirty
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battery voltage check 9 months 1 week ago #86220

EricTheCarGuy wrote:
This may be one of those situations where 'if it ain't broke, don't fix it'. The humidity sensor is not a critical component to the engine's operation. In fact, I believe it's only there for the HVAC. In fact, I'd doubt that you'd even know it was bad if you weren't looking. Actually, not knowing the scanner you're using, it could easily be a communication issue. Most DIY scanners don't read body codes.

I could be wrong, but if you're not experiencing any issues, I would recommend you leave well enough alone.

If you're looking to learn. Check out these articles I've written.

www.ericthecarguy.com/faq

Keep us posted.
Thanks Eric
I'm checking out the FAQs page and watching some of the videos about what to look for when buying and selling a used car, because I don't want to mess with the stock settings. I also want to understand better exactly what they are, so I'll know if I've changed any of them or if I've gotten the IMA update. The behavior of the system looks like I have had the IMA update, but it's not listed in the service history.
I've run 5 different self tests on the B-Can system and I was more interested in getting the sequence of what I've already done in print than I was in finding out about the other protocols in the networked system. ie: F-CAN, ISO and a couple others too. You mentioning body codes clicked and I realized rerunning the self test wouldn't be accessing the IMA system anyways.

grg8888 wrote:
The SOC indicator is a VERY approximate attempt at figuring out the battery charge.

The only REAL and ACCURATE way of figuring out SOC is to use a Hygrometer to measure the density of the battery acid.

The SOC gauge sort of does "dead reckoning", by assuming a certain level of starting charge and integrating the current in and current out and doing its best to estimate how much of the net input charge is sticking to the battery. All based on very approximate guesses and estimates.
Thanks grg
The SOC on my dash is probably even less accurate than an actual SOC built into a charger.
And the SOC's new behavior of jumping up to full and down to empty without ever showing anything of consequence in the middle of the SOC range has me wondering exactly what's up with it.
I'm looking around to see if I can save my $2000 battery pack or if I need to replace it.
That coupled with the fact ( as I understand it ) that the Honda IMA update reduces the range of the SOC to 30 - 70 % of capacity from 20 - 80 % of the IMA battery packs capacity.
I'm really still just trying to get a baseline of the cars condition and what are my best options for that condition.
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