Honda Jazz Forums => Honda Jazz Mk4 2020 - => Topic started by: RustyK on February 03, 2023, 05:24:15 AM
Title: Value of 1 bar of battery display
Post by: RustyK on February 03, 2023, 05:24:15 AM
Hi All, Have been trying to establish the approximate capacity of the bars displayed on the user interface. Have been using the following to test (engine is OFF) and car is in EV Ready mode.: AC=off and set to LO, all lights off, Fan Speed = MAX, audio off, time measured to drop from 6bars to 5bars in seconds. Average time to drop is 230 seconds. Assuming Max fan blower=250W+Background usage=100W for about 350W total. I do this after a drive to ensure the 12V battery is charged. Estimate that 1 bar = 0.028Kwh = 28Watt Hour. Does this seem reasonable? if this is the case the bars displayed only represent about 1 third of the battery capacity (0.28KwH). Comments welcome! Regards.
Title: Re: Value of 1 bar of battery display
Post by: Marco1979 on February 03, 2023, 05:51:35 AM
Interesting test! The accuracy comes merely from your power estimate of 250W and 100W. I don’t know whether these are realistic. Does anyone know?
What I also notice is that the top 1 or 2 bars are almost never used except when driving down mountains. Also the bottom 2 are always there, the engine kicking in to charge. So I suppose that maybe those 10 bars are not evenly spread across the battery range. It would be interesting to see if 5 to 4 and 4 to 3 also takes 230 seconds.
Title: Re: Value of 1 bar of battery display
Post by: shufty on February 03, 2023, 07:04:52 AM
... I've never seen less than 2 bars but frequently see 10 (no mountains involved ;D ) Tbh I've never thought the bars were an accurate measure of anything really just an indication of charge left, which as you know is up and down all the time.
Title: Re: Value of 1 bar of battery display
Post by: Kremmen on February 03, 2023, 07:18:48 AM
Same here, the only time I think it's accurate(ish) is on a journey after the battery has had to be charged when the meter has dropped to 3.
It then tends to rise and fall between 3 and 7
Title: Re: Value of 1 bar of battery display
Post by: Marco1979 on February 03, 2023, 08:47:04 AM
I like to check the distance covered between rises and falls. E.g. when cruising at 90 kmph (56 mph) on a warm day you see it drop from 7 to 3 while being in EV mode in around 800 meters. Then the engine kicks in and it needs around 1000 meters to get up to 7 again. This ratio (800 : 1000) tells me something about how efficient I drive. Unfortunately I do not own a Scangauge or anything; if I could figure out / read the amount of power the electric motor would develop, I could also calculate battery performance from these distances (including speed and EV power, obviously). Moreover it would also tell something about wear if done regularly e.g. every year. Or check efficiencies in summer versus in winter. Or... Or...
I can imagine Honda puts a low strain on the battery and uses not very danse battery packages. An EV would have 1 cycle (charge - discharge) every let's say 100 miles, while the Jazz does this every 1 or 2 miles. So across the entire life span, HEV's have had much more cycles than EV's.
Title: Re: Value of 1 bar of battery display
Post by: Lord Voltermore on February 03, 2023, 10:09:46 AM
I dont think you can accurately assess the capacity of bars in relation to the wattage consumption of 12volt systems such as fan blowers, radio etc ,aircon ,headlights etc. These take power from the the small 12volt battery. The power used by the 12v battery is topped up by the HV battery, so will indirectly deplete a bar in time, and require more petrol to top it up again. But the traction motor also shares the same 'Bar 'and will take the lions share of a 'bars worth' of power when active. And this amount of consumption tends to suggest the bars represent a large and relatively vague measurement subject to fluctuations in precise accuracy. I have never yet been able to predict when EV power will recharge itself, or not. Sometimes the engine starts when there are still plenty of bars, other times it does not start even when there are only 2-3. bars
I dont think waiting to see how quickly 12v systems alone would drop a bar would give a meaningful or accurate measure. You could probably tell using more sophisticated measuring instruments, but the bottom line is that any unnecessary use of heating, aircon etc comes with a small fuel penalty. Which will reveal itself as a change in mpg.
Title: Re: Value of 1 bar of battery display
Post by: Kremmen on February 03, 2023, 10:18:33 AM
TBH I don't really care what the bars are reading as long as the car is working, which mine is.
I've seen 10 bars come up after an overnight stand and no charging but that soon drops to 3 after a few miles.
Title: Re: Value of 1 bar of battery display
Post by: John Ratsey on February 03, 2023, 02:17:55 PM
I've always assumed that each bar equals 10% of the battery capacity. However, the minor flaw in this logic is whether 3 bars, for example, covers the range from 21% to 30% or from 25% to 35% as we need to know the charge level when the display changes the number of bars. The normal gauge range of 3 bars to 7 bars implies that the normal battery operating range is 30% to 70% or perhaps 35% to 7% percent. Such operation is plausible given that most of the wear on the lithium battery chemistry is caused by operation at the two ends of the charge range. I've got a dim recollection that someone claimed that the Car Scanner OBDII app could read the HR battery charge level. If true then this would improve our understanding of the gauge.
Title: Re: Value of 1 bar of battery display
Post by: Lincolnshire Rambler on February 03, 2023, 06:19:54 PM
If the hybrid drive train results from Hondas F1 knowledge then I suspect the control of the HV battery is very sophisticated and doing lots of things . I would imagine the controls ensure s the HV battery sees 10 or 1 bar at some described point based maybe on optimising the battery life. If you accelerate with an enthusiastic foot from several roundabouts (as on the A43 past silverstone ) the HV battery can show 3 bars or 9 , and has nothing to do with giving it the beans !! I expect the PCM figures load and battery temperature maybe driving style as well based on accelerator position / brake use . It must figure the actual cycle use of the HV battery and add it’s own conditioning cycle into the mix ? My last long (500 miles return ) journey in summer with 30 C heat and climate control on auto 19C all the time gave 73 mpg on A1 M11 M25 M2 to Kent and 71 mpg on the return leg .. figure that ….?? 😆😆😆. Outside of our group of users this level of tech isn’t appreciated !
Title: Re: Value of 1 bar of battery display
Post by: richardfrost on February 04, 2023, 09:01:07 AM
You lot have too much time on your hands.
Title: Re: Value of 1 bar of battery display
Post by: Lord Voltermore on February 04, 2023, 09:39:52 AM
Yeah sometimes there is too much information.
I have carried out a detailed analysis on how I spend my time overall and on the various instruments and accountancy possibilities on the Jazz and have concluded... - Nah Only Joking. ;D Ignorance is bliss. As long as I can still pay the bills its enough to know the Jazz is better than most cars.
Title: Re: Value of 1 bar of battery display
Post by: nowster on February 04, 2023, 11:51:02 PM
According to the CAN bus, 10 bars (full) on the display is 89% charge on the battery. I've not in the short time I've been monitoring yet seen the battery go below 25% charge.
Title: Re: Value of 1 bar of battery display
Post by: Kremmen on February 05, 2023, 07:14:34 AM
Which battery though ?
I've had multiple instances where I've been sitting on 3 or 4 bars, trickle charged my 12v battery and next powerful it's gone up to 10 bars.
Title: Re: Value of 1 bar of battery display
Post by: Jazzik on February 05, 2023, 09:49:09 AM
:o Then I think you have (secretly) connected the trickle charger to the HV battery... ;D
Title: Re: Value of 1 bar of battery display
Post by: Kremmen on February 05, 2023, 10:08:18 AM
That would be a good trick via the 12v terminals :)
Title: Re: Value of 1 bar of battery display
Post by: Lord Voltermore on February 05, 2023, 12:38:14 PM
I dont often bother looking at the charge bars these days when parking but IIRC there were sometimes a bar or two more after the car had been parked for a while. Thats without any external charging.
I believe that charge readings on lead acid batteries cells a can vary because of surface charge from recent battery activity but I dont know if, or how ,this affects readings on HV battery technology.
Title: Re: Value of 1 bar of battery display
Post by: Jazzik on February 05, 2023, 12:54:49 PM
I really wonder how important it can be to know the value of 1 bar (or 5 or maybe 9) on the battery display. I think in Japan they did their very best in developing the e:HEV powertrain. I trust what has been developed at Honda and have not been disappointed (so far). And what the "value"(?) of 1, 2, 3, 8 or 10 bars is, I honestly don't care much, if at all. The car is doing fine and as long as it stays that way I am satisfied (even with 10 or only 2 bars displayed).
Title: Re: Value of 1 bar of battery display
Post by: NoelM on February 05, 2023, 01:11:57 PM