Here is a question for those of you in the colder climates (which right now could be anybody north of Atlanta ).

I have noticed the last few days of cold temps here in Chattanooga that when the battery gets to about half charge it seems to charge even when just driving. Have any of you that drive in colder temps more often notice this happening?

Billy

 

temps were -1F this morning and is going to be -10F tonight in Madison, WI.
I do see occaisional extra charging even when my battery is full. Also cannot get full assist in my Insight when the battery is so cold.
Heck today it was so cold I could barely get the car to go into auto stop.

 

I had quite a time related to this with my dealer when my HCH was new.
IMA uses what some calls "hidden charging" or "trickle charging" while you drive.
There are no green charge bars visible, but you can see the bars on the battery state of charge rise one by one every couple of miles or so.
No regen or coasting charging required.

A month after I bought my car the IMA would allow the battery to drain way down to 1/4 charge before the green charge bars would appear.
Sometimes I'd drive all the way into work.... that's about an hours drive and 45 miles with a 3/4 discharged IMA battery.

Regen and foot-off-the accelerator was the only charge possible.

The catch was, it only happened on my afternoon drive, never at night.

What I mean is:
I start off with a 90% battery charge.
A few hills to pull and it drops a couple of bars.
I drive for 5 miles but no hidden charge.
A couple of more hills, a couple of bars drop off.
Miles pass and sitll no hidden charge.
Couple more hills and now I'm down below half charge.
Now I enter the freeway after 25 miles and the charge drops to about 1/3.
I begin to pull a freeway hill which drops it down to 1/4 and now green bars light and I'm charging hard.

At night I always get hidden charging when needed without fail.

I had the car in the dealer 6 (yes 6 times) and they told me it is supposed to work like that. But also they denied the existance of hidden charging so I'm not sure about their diagnosis.
They even consulted their support in California.
The last time my car was in for that they reset the computers (Fuse reseat) and that fixed it......until recently.
Lately it has been happening again now with the colder weather.

I'm not sure if it really is a problem because it doesn't seem to affect my overall MPG.
I've decided not to worry about it but will mention it in my next service schedule.

 

Steve,

It is funny you mentioned the hidden charging. It has been very cold here in AZ and I've been noticing the same thing. At first I thought it was my imagination - the way the light hit the dashboard, but it always happens when the battery is less than half.

I'm glad you mentioned it.

Thanks!

 

I have noticed the hidden charging before. I don't see any charge bars but the battery level goes up. What I have experienced the last few days is very obvious charging. I am driving down the road, foot on the gas pedal and there are 3 or 4 bars on the charge side of the meter. The charge state of the battery seems to always be around 1/2. I have just started noticing it when it has been cold.

Thanks for the discussion. Anybody else experience either of these things?

Billy

 

I was wondering about the hidden charge. Honda can deny it but I don't believe them. The charge goes up with no charge shown for sure.

I wish a couple things were different. My drive always starts with big hill climbs followed by smaller hills and ending with a big ole downhill. By the time I get to the big ole down hill the "hidden" charging has the pack charged to the point that downhill sections do not add any charge to the pack.

The "assist" works different on a cold engine than a warm one. I can climb at about 30mpg on a cold engine without kicking the assist on. Once the car warms up the assist starts kicking in at around 45mpg so it is impossible to climb hills without the assist kicking in. I like to use assist for acceleration but not hill climbing. This actually works in my favor as the biggest hill climb is when the engine is still cool.

 

As an electronic technition gone mechanic, I may have some "insight" to what is realy going on with the charging system.
I have noticed the battery evaluates itself just about every time computer codes or a data stream are accessed by a scan tool. i keep seeing mentions of a "hidden charging system" as well.
The batteries in the HCH are not realy batteries in the chemical sense as much as they are a bank of capacitors. the monitoring system is as far as i can tell, a mini management system for the capacitors. I believe it is posible for this system to move the charge around and test capacitance abilities, and during this, you will see the meter do strange things. This hidden charging thing may just be the charge being moved around in the bank of capacitors, and making the meter fluctuate. Maybe the monotor only sees one of the capacitors. If anyone has any comment, i welcome it. I am trying to learn myself. Honda is being very tight liped to aftermarket machanics about this stuff.

 

Hi All:

___A bit of Insight With an Insight 5-speed, hidden charging as it is commonly described has been understood for years. At steady highway cruise, the SoC no matter where it was at the time you started her up will work its way back up towards 19 of 20 bars as long as you are not using Assist in any fashion. In very cold temps, hidden and even sometimes forced charging can be seen as there is a hidden and non-hidden forced charge to warm up the pack. This can be seen as 4 bars of non-hidden Charging when just driving off or idling from an initial very cold start … We are talking 5 degrees F and below type temperatures for the forced non-hidden charging to warm up the pack irregardless of SoC from the night before.

___And to help answer some other questions about hidden charging on the HCH although this is Insight specific … Having your headlights on will always induce hidden charging up to 19 of 20 bars on the Insight. By Hot_Georgia_2004’s HCH detailed experiences of day/night driving, I can bet the HCH’s BCM is doing the exact same during the night time hours. In other words, with the headlights on, you are receiving hidden charging and it will take the SoC right back up to its std. 80% of max cap or 19 of 20 bars. This is as it was designed to do.

___What I do not understand or necessarily like is that the HCH does not run any hidden charging in day light hours to bring the pack back up to 19 of 20 bars? This is not anything like the Insight 5-speeds.

___Lakedude, we are going to have to exchange vehicles sometime this summer as I really need to get behind the wheel of an HCH for some distance hypermiling to learn its inner secrets. The fact I want to receive 70 + mpg over a lengthy segment from one wouldn’t have anything to do with it … Trust me on this

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net

 

Wayne, all last summer hidden charging worked fine.

When it began to get really cold here (32-45) hidden charging began to be intermittant, again in the daytime only.

Lately, hidden charging is almost non-existant, except for night, when it always works.

The possability of it being linked to the headlights has me intrigued......
I'll start using my headlights during my afternoon commute and see if this charging comes back on. I REALLY hate it not working. I'll spend my 1st 22 miles on curvy, hilly country roads and just when I need to jump to 60-65MPH freeway speeds it's just began charging from 2/3 depletion, fighting freeway hills.

As we know, freeway acceleration & speeds + mostly discharged SOC = poor FE for miles on end.

 

Wayne,thank you for the hidden charging info.
Today I switched the headlights on before leaving and hidden charging worked great.

To be sure I'll use my headlights durring the day. It's safer anyway.
A few more daytime commutes will confirm this, but I expect the same good results.