WattsLeft™ Monitor (Parallax SX28AC/DP SOC/CAN Project)

KillaWhat said:

19% and 56GID still showing.

Which leads me to a couple questions for the group.
At what point (GID's) does the car stop rolling?
Stop performing in a normal manner?
(maybe should have asked that first?)

And.... is the battery indicator just full of it?
0 bars and 19% left?

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SOC%-"kWh usable" --Gid----Gid%--Gid2%---2013 dash %
95.x% -21.0--Full----281---100%---100%----100%
-------- 3.1---LBW----49---17.4%---15.3%----17%
---------1.3---VLB----24----8.6%-----6.2%----8%
2.x%-- 0.0---Turtle --7-----2.5%-----0%-----(---)

Turtle can be triggered between about 4 and 8 Gid. The car physically stops when the lowest cell pair hits the target low voltage, usually around 3-5 Gid (it can vary a lot... Get off the road at turtle).

KillaWhat said:

But the Meter said I had 112GID, which sounded like I had plenty of E-fuel.

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112 GID is about 1/2 a 80% charge to give you some perspective...

KillaWhat said:

Arrived home with NO bars left, but the meter showed 19% and 56GID still showing.

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Not even LBW!

KillaWhat said:

At what point (GID's) does the car stop rolling?

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Typically around 4 GIDs (See Tony's great chart above for all the good details)

KillaWhat said:

Stop performing in a normal manner?

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Turtle typically comes on around 5-7 GIDs depending on how hard you're driving, but power starts being restricted slightly before that. It would be safe to assume < 10 GIDs = restricted power. Note that I would recommend driving gently as get below LBW (49 GIDs) and as you approach VLBW (24 GIDs). Especially once you get below VLBW I'd be as gentle as possible. It's tough on the battery to be discharged quickly when SOC is low.

KillaWhat said:

And.... is the battery indicator just full of it?
0 bars and 19% left?

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The battery gauge used to be more optimistic until the the first LEAF owners started Brodering the car on the side of the road in somewhat large numbers. Making the meter pessimistic at the bottom has largely alleviated that issue, at the expensive of making it appear to the normal user that range is lower than it really is.

Thank you.
This ability to ACTUALLY see what's really happening is a game changer.

KillaWhat said:

Thank you.
This ability to ACTUALLY see what's really happening is a game changer.

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I couldn't agree more! Before WattsLeft™ , once I was down to two bars I would turn off the heater and go into my "hypermile" mode. Now I find myself actually being less efficient, but has made driving a lot more relaxing.

As drees stated, once you get down to three bars, Nissan starts being ultra pessimistic, with the GOM and SOC deviating by a greater degree.

KillaWhat said:

Well I did something new tonight.
With my new Wattsleft meter installed, I headed out for a 20 mile trip with 3 battery bars ...

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I am impressed. You did the rearview mirror install. Now that it is getting hotter here I had to go back to adding the metal hook I made to keep my WattsLeft up as the glue would soften and the unit drop down. If you go back many pages you can see what the hook looks like.

Actually, I don't even recall sending you the detailed instructions on how to do it.

If you go back many pages you can see what the hook looks like.

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You are 100% correct.
The adhesive on the Velcro stuck to the headliner will not survive the first hot day.
I tried a trick I used to use when sticking things to carpeted areas In the past.
Just stick the "hook" part to the unit, and wiggle it into the headliner.
The headliner acts as the "loop" side.
Doesn't always work, but this seems to be OK.

It was 89F here yesterday, and damn hot in the black leaf I can tell you.
Everything held.

Loving the meter.

I held out for so long waiting for a Leafscan.......
Now the thread is locked with no explanation?

My email has been sent. I hope Turbo has the time to get a meter to me before the Rally in late June.

Just got my meter today. Damn you Turbo! Now I'll have to change all of my rally driving logs from fuel bars to gids! :lol:

What affects the max gid value besides battery degradation? Does temperature and/or cell imbalance?

BTW It looks great!

Luft said:

Does temperature and/or cell imbalance?

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Yes -- both. Good on you to get Jim's meter, it's one of the most well thought-out solutions available today.

If the cells are not well equalized, the battery pack cannot
be charged as much as would otherwise be possible.

At higher and lower temperatures, the car's BMS will be
more conservative, and not fill the Battery Pack as full
as it would at "nominal" temperatures, primarily to
better protect the battery cells from damage.

With real diminished capacity, the Battery Pack cannot
hold as much energy as it previously could.

These three major factors combine to give lower
GID values when the Battery is "full".

A couple of questions about your impressive product. From pg 9 Quick Guide, am I correct to assume that SOC in upper left corner of screen 1 is the State of Charge % relative to the current battery capacity, and not Gids/281?

I have become very comfortable with % = Gids/281 on my original Gid meter, now 1.5 years old. I call this value Gid% to distinguish it from the first definition. With my driving, 1 mile is very close to 1% Gid%, and I can apply corrections based upon upcoming elevation changes to estimate my margin at my destination. This relationship doesn't change as my battery loses capacity.

Since you have access to the Gid values with WattsLeft, unlike the current ELM287, would you consider adding an option to display Gid% instead of SOC on Screen 1?

WattsLeft SOC% is gids/281.

Turbo3 said:

WattsLeft SOC% is gids/281.

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Ok, then my request would be to rename this to Gid% instead of SOC%.

In the WattsLeft world there are only Gids so 100% 'SOC' =281 Gids.

When you sell a product to the general public you have to keep it as simple as possible.

There are no 'SOC' labels on the display anyway so nothing to change there, just xx.x%.

Just look at all the discussion going on about AHr, SOC, gids. I don't want to get into all that.

When you hit a certain gid level the car gives you a low battery warning or very low battery warning. So the amount of Gids you have left is of some importance to the car and should be to the driver.

How many gids per KWh?

A new fully charged battery pack holds 281 gids. Does that represent the usable 21 KWh or the maximum 24 KWh?

I'm thinking that the 281 number is based off of the usable KWh in a fresh fully charged pack which would make it about 13.4 gids per KWh but I want to be sure.

Thanks.

Luft said:

How many gids per KWh?

A new fully charged battery pack holds 281 gids. Does that represent the usable 21 KWh or the maximum 24 KWh?

I'm thinking that the 281 number is based off of the usable KWh in a fresh fully charged pack which would make it about 13.4 gids per KWh but I want to be sure.

Thanks.

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300 Gids represents 24kwh, since each Gid unit is 80 wattHours stored. When you consume those Gids, the value is about 76 wattHours each. That 76 value per Gid will decrease with temperature below 70F degrees, plus the sensors themselves have a hard time being accurate with temperature change. In addition, the total quantity of Gids at a full charge will decrease with degradation over time, cycles, exposure to heat, depth of discharge, time left at high states of charge, etc.

281 Gids is a fully charged, new condition LEAF battery, or about 22.48kWh stored. When that is consumed, there would be about 21.4kWh to be burnt to a completely dead battery, however, approximately 400 wattHours are not available to be burned at the bottom to prevent "bricking" the battery. That leaves 21kWh burned for about 281 Gids minus about 5 Gid at battery low energy cutoff.

281 - 5 = 276 Gid available * 76 wattHour each = 20.976kWh available to you. All this assumes new condition battery at 70F degrees. Again, a colder battery will have less available energy, and a degraded battery will be reflected with lower than 281 Gid at full charge.

There is no magic bullet of Gid = X kWh, however 276 Gid / 21kwh available = 13.14 Gid per kWh at 70F.

TonyWilliams said:

Luft said:

How many gids per KWh?

A new fully charged battery pack holds 281 gids. Does that represent the usable 21 KWh or the maximum 24 KWh?

I'm thinking that the 281 number is based off of the usable KWh in a fresh fully charged pack which would make it about 13.4 gids per KWh but I want to be sure.

Thanks.

Click to expand...

300 Gids represents 24kwh, since each Gid unit is 80 wattHours stored. When you consume those Gids, the value is about 76 wattHours each. That 76 value per Gid will decrease with temperature below 70F degrees, plus the sensors themselves have a hard time being accurate with temperature change. In addition, the total quantity of Gids at a full charge will decrease with degradation over time, cycles, exposure to heat, depth of discharge, time left at high states of charge, etc.

281 Gids is a fully charged, new condition LEAF battery, or about 22.48kWh stored. When that is consumed, there would be about 21.4kWh to be burnt to a completely dead battery, however, approximately 400 wattHours are not available to be burned at the bottom to prevent "bricking" the battery. That leaves 21kWh burned for about 281 Gids minus about 5 Gid at battery low energy cutoff.

281 - 5 = 276 Gid available * 76 wattHour each = 20.976kWh available to you. All this assumes new condition battery at 70F degrees. Again, a colder battery will have less available energy, and a degraded battery will be reflected with lower than 281 Gid at full charge.

There is no magic bullet of Gid = X kWh, however 276 Gid / 21kwh available = 13.14 Gid per kWh at 70F.

Click to expand...

Thanks Tony, that's very helpful.

Turbo3 said:

When you hit a certain gid level the car gives you a low battery warning or very low battery warning. So the amount of Gids you have left is of some importance to the car and should be to the driver.

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Jim, I really appreciate all the work that has gone into WattLeft and the ELM327 project, and I don't want to open another unnecessary discussion, since I know how hard it is to get consensus here. It took a lot of effort to get an agreement on 21 kWh usable and on 24 kWh rated capacity a while back, for example. There will always be folks with some kind of bias or a personal opinion. It's just the way it is with these things. That said, Nissan has not indexed the instruments in the LEAF to some imaginary values. No, they have been calibrated to certain levels of stored energy.

Take the low battery warning, for example. It comes up at 4 kWh stored energy remaining, which is a constant and does not change over time as the battery degrades. The very low battery warning comes up at 2 kW stored energy remaining. This is not just my opinion, these design decisions are a matter of public record. Since we are essentially reverse engineering the car, it takes effort and sometimes even faith to bridge the gaps in our understanding. Gids are units of stored energy, and not SOC, as was originally assumed. They represent watt-hours and kilowatt-hours, which are universally understood as units of energy.

WattsLeaf is an excellent product, and you might not want to redesign it. That said, before the next revision of the LEAF platform and before a different battery pack is released, it would be good to agree that it's beneficial to find a way to express stored energy in universal units of measure. It won't help matters if a certain group of LEAF owners was looking at raw CAN bus values, which meant one thing, and another group of owners would use something different, because their LEAF had a new battery pack and new software.

Going from an old LEAF to a new LEAF would be a big transition, since these aftermarket devices would use different raw values from the CAN bus. If kilowatt-hours were used, then the transition would be seamless. Besides, isn't one of the goals that Nissan should show kWh directly on the dash? It would be good if the strong engineering community we have here set the right tone at some point in the not-too-distant future, and demonstrated that this approach can work.

Do you have any yellow OLED units left? Is the firmware field upgradable? Have you ever considered installing a rechargeable battery to prevent data loss in case of 12V battery failure (or someone unplugging it)?

The yellow OLED screens look amazing.

From the last production run I have three of the Yellow WattsLefts remaining. However, I have two on hold that are just awaiting PayPal payment before I ship them which should happen on Monday. So that leaves just one Yellow OLED unit remaining.

I will start another build the middle of June and all those will have the option of the Yellow OLED display. There is also one base Blue LCD without Bluetooth available.

The firmware is upgradable but it requires a special adapter ($60+) so the unit would need to be shipped back to me if I ever come up with newer firmware (no plans at this time). Shipping would be around $5 and I would ship the unit back free.

I have thought about a supercap but that is about it.

With the bluetooth option the history data can be externally saved with an Android app I am working on. There is a test version of the app that just displays the history data on the android device but does not currently save it. When finished it would merge the history data into a CSV file.

Yes the OLED display is very nice.