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Discussion Starter #1
Do users of the link-10/E-gauge: do you find the Peukert correction works out pretty well in terms of measuring remaining amp-hours? Does anyone else with similar tracking gauge offer Peukert correction?

TIA



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Discussion Starter #2
Hello Frank,

I am using Trojan 6 volt T-145's and program in the Peukert, the 260 AH
value and battery pack voltage into the Link-10 E-meter.

To set up this meter, I first charge the batteries to 1.275 SG which should
be about 100% charge. I set my E-meter to 0.00 AH and let it read to the
negative side as I discharge the batteries. If it reads -260 AH, this
should be 100% discharge or -130 AH for 50% State of Charge (S.O.C.)

To test out this meter the first time, I watch how much AH I remove at 80%
State of Charge which means, that should have remove about 52 AH from the
batteries. My voltage should now read 187.6 volts and the specific gravity
should read about 1.238 SG at the 80% S.O.C.

When the percentage meter on the Link-10 began to light up the 79.9 or about
80% indication, my AH hour may read in a range of 48 AH to 53 AH. This
difference is cause by not charging the batteries exactly right to the 100%
indication, may be over or under. This is not too critical for me, because
I do not need the range and the state of charge is always above 70 percent.

This is how I get a very long life out of my batteries.

Roland




----- Original Message -----
From: "Frank John" <[email protected]>
To: <[email protected]>
Sent: Wednesday, October 31, 2007 9:49 AM
Subject: [EVDL] E-Gauge Peukert Correction question


> Do users of the link-10/E-gauge: do you find the Peukert correction works
> out pretty well in terms of measuring remaining amp-hours? Does anyone
> else with similar tracking gauge offer Peukert correction?
>
> TIA
>
>
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam? Yahoo! Mail has the best spam protection around
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Discussion Starter #3
Thanks Roland. So if I understand correctly, you expect to draw 52 AH at 80% DOD and this is pretty much what you measure using Link's recommended Peukert factor? Out of curiosity, what discharge rate did you choose?

thanks,
Frank


----- Original Message ----
From: Roland Wiench <[email protected]>
To: Electric Vehicle Discussion List <[email protected]>
Sent: Wednesday, October 31, 2007 3:57:41 PM
Subject: Re: [EVDL] E-Gauge Peukert Correction question


Hello Frank,

I am using Trojan 6 volt T-145's and program in the Peukert, the 260 AH

value and battery pack voltage into the Link-10 E-meter.

To set up this meter, I first charge the batteries to 1.275 SG which
should
be about 100% charge. I set my E-meter to 0.00 AH and let it read to
the
negative side as I discharge the batteries. If it reads -260 AH, this
should be 100% discharge or -130 AH for 50% State of Charge (S.O.C.)

To test out this meter the first time, I watch how much AH I remove at
80%
State of Charge which means, that should have remove about 52 AH from
the
batteries. My voltage should now read 187.6 volts and the specific
gravity
should read about 1.238 SG at the 80% S.O.C.

When the percentage meter on the Link-10 began to light up the 79.9 or
about
80% indication, my AH hour may read in a range of 48 AH to 53 AH. This

difference is cause by not charging the batteries exactly right to the
100%
indication, may be over or under. This is not too critical for me,
because
I do not need the range and the state of charge is always above 70
percent.

This is how I get a very long life out of my batteries.

Roland




----- Original Message -----
From: "Frank John" <[email protected]>
To: <[email protected]>
Sent: Wednesday, October 31, 2007 9:49 AM
Subject: [EVDL] E-Gauge Peukert Correction question


> Do users of the link-10/E-gauge: do you find the Peukert correction
works
> out pretty well in terms of measuring remaining amp-hours? Does
anyone
> else with similar tracking gauge offer Peukert correction?
>
> TIA
>
>
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam? Yahoo! Mail has the best spam protection around
> http://mail.yahoo.com
>
> _______________________________________________
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> http://lists.sjsu.edu/mailman/listinfo/ev
>

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Discussion Starter #4
Hello Frank,

The discharge rate is set to 50%. My average discharge ampere is about 75
amps which these batteries are rated at 145 minutes reserve capacity.

If my 260 AH batteries has a 20 hour discharge at about 13 amps per hour,
then at 75 amps they are rated for 145 minutes which the ampere-hour usage
is now:

145 min / 60 = 2.41 hrs

2.41 hr x 75 amps = 181.2 amp-hrs

So when I discharge to 80% using about 52 AH, the average time is:


(145 min x 52 amp-hrs)/181.2 amp-hrs = 41.6 min

My city driving is about a average of 4 minutes per mile, so this makes a
range of about 41.6/4 = 10 miles at 80% State of Charge (SOC)

This will give you some examples how to calculated if your battery is the
correct type for the usage you want.

The first thing I look at in choosing a deep cycle battery is the rate of
discharge in minutes at the average battery amperes I will be using. Then I
see if I can keep above 50% SOC for the distance, speed and time that I will
be using this battery.

It is best if you can keep at or above 75% SOC for a very long life.

Roland





----- Original Message -----
From: "Frank John" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Thursday, November 01, 2007 7:59 AM
Subject: Re: [EVDL] E-Gauge Peukert Correction question


> Thanks Roland. So if I understand correctly, you expect to draw 52 AH at
> 80% DOD and this is pretty much what you measure using Link's recommended
> Peukert factor? Out of curiosity, what discharge rate did you choose?
>
> thanks,
> Frank
>
>
> ----- Original Message ----
> From: Roland Wiench <[email protected]>
> To: Electric Vehicle Discussion List <[email protected]>
> Sent: Wednesday, October 31, 2007 3:57:41 PM
> Subject: Re: [EVDL] E-Gauge Peukert Correction question
>
>
> Hello Frank,
>
> I am using Trojan 6 volt T-145's and program in the Peukert, the 260 AH
>
> value and battery pack voltage into the Link-10 E-meter.
>
> To set up this meter, I first charge the batteries to 1.275 SG which
> should
> be about 100% charge. I set my E-meter to 0.00 AH and let it read to
> the
> negative side as I discharge the batteries. If it reads -260 AH, this
> should be 100% discharge or -130 AH for 50% State of Charge (S.O.C.)
>
> To test out this meter the first time, I watch how much AH I remove at
> 80%
> State of Charge which means, that should have remove about 52 AH from
> the
> batteries. My voltage should now read 187.6 volts and the specific
> gravity
> should read about 1.238 SG at the 80% S.O.C.
>
> When the percentage meter on the Link-10 began to light up the 79.9 or
> about
> 80% indication, my AH hour may read in a range of 48 AH to 53 AH. This
>
> difference is cause by not charging the batteries exactly right to the
> 100%
> indication, may be over or under. This is not too critical for me,
> because
> I do not need the range and the state of charge is always above 70
> percent.
>
> This is how I get a very long life out of my batteries.
>
> Roland
>
>
>
>
> ----- Original Message -----
> From: "Frank John" <[email protected]>
> To: <[email protected]>
> Sent: Wednesday, October 31, 2007 9:49 AM
> Subject: [EVDL] E-Gauge Peukert Correction question
>
>
> > Do users of the link-10/E-gauge: do you find the Peukert correction
> works
> > out pretty well in terms of measuring remaining amp-hours? Does
> anyone
> > else with similar tracking gauge offer Peukert correction?
> >
> > TIA
> >
> >
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Tired of spam? Yahoo! Mail has the best spam protection around
> > http://mail.yahoo.com
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> > _______________________________________________
> > For subscription options, see
> > http://lists.sjsu.edu/mailman/listinfo/ev
> >
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>
>
>
>
> __________________________________________________
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> Tired of spam? Yahoo! Mail has the best spam protection around
> http://mail.yahoo.com
>
> _______________________________________________
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>

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Discussion Starter #5
Frank John wrote:
> Do users of the link-10/E-gauge: do you find the Peukert correction
> works out pretty well in terms of measuring remaining amp-hours?
> Does anyone else with similar tracking gauge offer Peukert
> correction?

The Peukert correction works very well if set correctly. But this
involves figuring out what your pack's *true* peukert exponent and
capacity are (and not just blindly accepting the data sheets).

You also need to be aware of what Peukert is telling you. It only
applies to your fuel gauge (the "empty-full" bargraph LEDs at the top,
or the 0-100% display if you set the E-meter to show it).

I don't know of any other commercial meters that offer Peukert
correction, though the "fuel gauges" in the recent auto company produced
EVs all had it.

--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net

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Discussion Starter #6
Well, something to be aware of. Most of these meters start from the
Peukert equation, they call it Peukert's, but what they implement is not
Peukert's.

Here's the thing. Say with your Peukert exponent, at 75 amps, Peukert's
says your 80AH battery is good for 40AH. Now the historically stated
Peukert eq does not address varying current draw and doesn't say what
the equation means. As I understand it, the real-world situation is
that this is saying that under 50% DOD (40AH left) the battery cannot
put out 75 amps so the last 40AH are unusable. However, there are still
40AH in the batt and charging needs to add 40AH.

The problem in creating a meter is that varying current draws- up and
down hills, coming off stop lights- makes it difficult to predict what
you want to draw. If you need to draw 50A you have much more capacity
than if you need to draw 100A. So if the draw at this moment is 100A
then you have little capacity and if you let off the throttle and go
down to 50A then there is more capacity. This is the reality of the
situation, but a gas gauge that goes up and down confuses some people.

What eMeter and others did is that if you're drawing 75A and, Peukert's
says your 80AH batt is good for 40AH at this level, that as 1AH is used
it just deducts 2AH from the 80AH total. This is not correct in several
ways. The meter will say 80AH is used when the batt's put out 40AH and
can no longer be driven, but there's actually only 40AH used and the
charger only needs to add 40AH. Under varying current loads it will
give wrong answers. For example, if you were run down 40AH at low loads
where Peukert's is not significant then the meter won't use a multiplier
and it reads 40AH left. At this point it has no capacity at all for a
75A discharge, but the meter will say there's 40AH left and deduct 2AH
for every amp-hr used. So basically going from a low discharge rate to
a high discharge rate will result in an erroneously high capacity, even
reading that there is capacity left when no Peukert capacity exists.

It has the opposite prob going from a high rate to a lower rate. Start
with a full batt and the meter zeroed, a batt run down to 50% DOD has
40AH left. It has no capacity for a 75A discharge rate. It does have
capacity for easing the throttle and limping along at 40A, but the meter
will still read zero.

Danny

>----- Original Message ----
>From: Roland Wiench <[email protected]>
>To: Electric Vehicle Discussion List <[email protected]>
>Sent: Wednesday, October 31, 2007 3:57:41 PM
>Subject: Re: [EVDL] E-Gauge Peukert Correction question
>
>
>Hello Frank,
>
>I am using Trojan 6 volt T-145's and program in the Peukert, the 260 AH
>
>value and battery pack voltage into the Link-10 E-meter.
>
>To set up this meter, I first charge the batteries to 1.275 SG which
> should
>be about 100% charge. I set my E-meter to 0.00 AH and let it read to
> the
>negative side as I discharge the batteries. If it reads -260 AH, this
>should be 100% discharge or -130 AH for 50% State of Charge (S.O.C.)
>
>To test out this meter the first time, I watch how much AH I remove at
> 80%
>State of Charge which means, that should have remove about 52 AH from
> the
>batteries. My voltage should now read 187.6 volts and the specific
> gravity
>should read about 1.238 SG at the 80% S.O.C.
>
>When the percentage meter on the Link-10 began to light up the 79.9 or
> about
>80% indication, my AH hour may read in a range of 48 AH to 53 AH. This
>
>difference is cause by not charging the batteries exactly right to the
> 100%
>indication, may be over or under. This is not too critical for me,
> because
>I do not need the range and the state of charge is always above 70
> percent.
>
>This is how I get a very long life out of my batteries.
>
>Roland
>
>
>
>
>----- Original Message -----
>From: "Frank John" <[email protected]>
>To: <[email protected]>
>Sent: Wednesday, October 31, 2007 9:49 AM
>Subject: [EVDL] E-Gauge Peukert Correction question
>
>
>
>
>>Do users of the link-10/E-gauge: do you find the Peukert correction
>>
>>
> works
>
>
>>out pretty well in terms of measuring remaining amp-hours? Does
>>
>>
> anyone
>
>
>>else with similar tracking gauge offer Peukert correction?
>>
>>TIA
>>
>>
>>
>>__________________________________________________
>>Do You Yahoo!?
>>Tired of spam? Yahoo! Mail has the best spam protection around
>>http://mail.yahoo.com
>>
>>_______________________________________________
>>For subscription options, see
>>http://lists.sjsu.edu/mailman/listinfo/ev
>>
>>
>>
>
>_______________________________________________
>For subscription options, see
>http://lists.sjsu.edu/mailman/listinfo/ev
>
>
>
>
>__________________________________________________
>Do You Yahoo!?
>Tired of spam? Yahoo! Mail has the best spam protection around
>http://mail.yahoo.com
>
>_______________________________________________
>For subscription options, see
>http://lists.sjsu.edu/mailman/listinfo/ev
>
>
>

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Discussion Starter #7
I believe you are incorrect on several points.

Peukert's equation is:
Current^PN * time = PC

PN =Peukert's Number
PC = Peukert's Capacity

>From what I understand the E-meter uses the Peukerts Capacity of the pack
(basically how many AH at a 1amp draw), which MUST be entered by the user,
then it takes the Peukert's Number(also entered by the user) for the
batteries and calculates how much the Peukerts capacity has been drained
on a moment by moment basis.

Let's say the pack has a Peukert's capacity of 100 AH and a PN of 1.2

If we draw 60 amps for 30 seconds then 20^1.2 * 0.008333 hours = 1.34 AH
so the remaining capacity is 98.66 AH

If we then draw 200 amps for 4 minutes, 200^1.2 * 0.0667 hours = 38.47AH
remaining capacity is now 98.66-38.47 = 60.19 AH and so on.


> Well, something to be aware of. Most of these meters start from the
> Peukert equation, they call it Peukert's, but what they implement is not
> Peukert's.
>
> Here's the thing. Say with your Peukert exponent, at 75 amps, Peukert's
> says your 80AH battery is good for 40AH. Now the historically stated
> Peukert eq does not address varying current draw and doesn't say what
> the equation means. As I understand it, the real-world situation is
> that this is saying that under 50% DOD (40AH left) the battery cannot
> put out 75 amps so the last 40AH are unusable. However, there are still
> 40AH in the batt and charging needs to add 40AH.
>
> The problem in creating a meter is that varying current draws- up and
> down hills, coming off stop lights- makes it difficult to predict what
> you want to draw. If you need to draw 50A you have much more capacity
> than if you need to draw 100A. So if the draw at this moment is 100A
> then you have little capacity and if you let off the throttle and go
> down to 50A then there is more capacity. This is the reality of the
> situation, but a gas gauge that goes up and down confuses some people.
>
> What eMeter and others did is that if you're drawing 75A and, Peukert's
> says your 80AH batt is good for 40AH at this level, that as 1AH is used
> it just deducts 2AH from the 80AH total. This is not correct in several
> ways. The meter will say 80AH is used when the batt's put out 40AH and
> can no longer be driven, but there's actually only 40AH used and the
> charger only needs to add 40AH. Under varying current loads it will
> give wrong answers. For example, if you were run down 40AH at low loads
> where Peukert's is not significant then the meter won't use a multiplier
> and it reads 40AH left. At this point it has no capacity at all for a
> 75A discharge, but the meter will say there's 40AH left and deduct 2AH
> for every amp-hr used. So basically going from a low discharge rate to
> a high discharge rate will result in an erroneously high capacity, even
> reading that there is capacity left when no Peukert capacity exists.
>
> It has the opposite prob going from a high rate to a lower rate. Start
> with a full batt and the meter zeroed, a batt run down to 50% DOD has
> 40AH left. It has no capacity for a 75A discharge rate. It does have
> capacity for easing the throttle and limping along at 40A, but the meter
> will still read zero.
>
> Danny
>
>>----- Original Message ----
>>From: Roland Wiench <[email protected]>
>>To: Electric Vehicle Discussion List <[email protected]>
>>Sent: Wednesday, October 31, 2007 3:57:41 PM
>>Subject: Re: [EVDL] E-Gauge Peukert Correction question
>>
>>
>>Hello Frank,
>>
>>I am using Trojan 6 volt T-145's and program in the Peukert, the 260 AH
>>
>>value and battery pack voltage into the Link-10 E-meter.
>>
>>To set up this meter, I first charge the batteries to 1.275 SG which
>> should
>>be about 100% charge. I set my E-meter to 0.00 AH and let it read to
>> the
>>negative side as I discharge the batteries. If it reads -260 AH, this
>>should be 100% discharge or -130 AH for 50% State of Charge (S.O.C.)
>>
>>To test out this meter the first time, I watch how much AH I remove at
>> 80%
>>State of Charge which means, that should have remove about 52 AH from
>> the
>>batteries. My voltage should now read 187.6 volts and the specific
>> gravity
>>should read about 1.238 SG at the 80% S.O.C.
>>
>>When the percentage meter on the Link-10 began to light up the 79.9 or
>> about
>>80% indication, my AH hour may read in a range of 48 AH to 53 AH. This
>>
>>difference is cause by not charging the batteries exactly right to the
>> 100%
>>indication, may be over or under. This is not too critical for me,
>> because
>>I do not need the range and the state of charge is always above 70
>> percent.
>>
>>This is how I get a very long life out of my batteries.
>>
>>Roland
>>
>>
>>
>>
>>----- Original Message -----
>>From: "Frank John" <[email protected]>
>>To: <[email protected]>
>>Sent: Wednesday, October 31, 2007 9:49 AM
>>Subject: [EVDL] E-Gauge Peukert Correction question
>>
>>
>>
>>
>>>Do users of the link-10/E-gauge: do you find the Peukert correction
>>>
>>>
>> works
>>
>>
>>>out pretty well in terms of measuring remaining amp-hours? Does
>>>
>>>
>> anyone
>>
>>
>>>else with similar tracking gauge offer Peukert correction?
>>>
>>>TIA
>>>
>>>
>>>
>>>__________________________________________________
>>>Do You Yahoo!?
>>>Tired of spam? Yahoo! Mail has the best spam protection around
>>>http://mail.yahoo.com
>>>
>>>_______________________________________________
>>>For subscription options, see
>>>http://lists.sjsu.edu/mailman/listinfo/ev
>>>
>>>
>>>
>>
>>_______________________________________________
>>For subscription options, see
>>http://lists.sjsu.edu/mailman/listinfo/ev
>>
>>
>>
>>
>>__________________________________________________
>>Do You Yahoo!?
>>Tired of spam? Yahoo! Mail has the best spam protection around
>>http://mail.yahoo.com
>>
>>_______________________________________________
>>For subscription options, see
>>http://lists.sjsu.edu/mailman/listinfo/ev
>>
>>
>>
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>


--
If you send email to me, or the EVDL, that has > 4 lines of legalistic
junk at the end; then you are specifically authorizing me to do whatever I
wish with the message. By posting the message you agree that your long
legalistic signature is void.

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Discussion Starter #9
Brian Staffanson wrote:
> Lee, how do you find out the *true* Peukert exponent?

You test the battery's capacity at two different load currents. Plot the
two points on log graph paper (amps on vertical scale, 1-2-4-8-16...)
and hours on the horizontal scale 10-20-30). Draw a straight line to
connect the two dots. Read the capacity off the graph for any other
discharge current.

Peukert's equation is not based on physics -- it is just fitting a curve
to the battery's actual tested behavior.

You can do the same thing mathematically, if you're so inclined. The
equation is in the E-meter's manual. It's awkward to type, so I won't
try to do it for you here (you can look it up online if you're interested).

> Would you test one battery, and assume the same for the pack?
> Or test all of the batteries?

You test the pack as a whole, as one big battery. Discharge it at some
low current (say, with only your heater running), and record the hours
to a known cutoff point (like 1.75v/cell). Recharge, and then discharge
it at some high current (like 100 amps, or whatever you can scrounge
together a high-current dummy load for), and record the time to the same
ending voltage.

> It seems in my poor overcrowded memory, it was once talked about an
> open-source emeter. I have tried to find it in the archives, but
> have not had much luck. Does anyone remember this?

It's been discussed, and a number of people have worked on them. It
seems that they discover it's a harder problem than they thought, so it
gets shelved, or only partially implemented, or becomes a commercial
product that is just as expensive as the E-meter.
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net

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Discussion Starter #10
I ask this because it doesn't seem that the commercial E-meter does all of
what I would like it to do. Nothing quite does. But I guess I don't need
to collect all of the information all of the time.

thanks,
Brian

>
>
> > It seems in my poor overcrowded memory, it was once talked about an
> > open-source emeter. I have tried to find it in the archives, but
> > have not had much luck. Does anyone remember this?
>
> It's been discussed, and a number of people have worked on them. It
> seems that they discover it's a harder problem than they thought, so it
> gets shelved, or only partially implemented, or becomes a commercial
> product that is just as expensive as the E-meter.
> --
> Ring the bells that still can ring
> Forget the perfect offering
> There is a crack in everything
> That's how the light gets in -- Leonard Cohen
> --
> Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>
_______________________________________________
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70 Posts
Discussion Starter #11
Have you checked out Victor's E-vision yet? He solicited a lot of input fr=
om this list first then went out and designed a beautiful new meter. Oh ye=
ah, it costs even more than an E-meter :-( but that did not keep me from pu=
tting in an order for one. You find after doing this for a while that ther=
e are definitely things worth spending money on, and a great meter has made=
it up towards the top of my list.

http://www.metricmind.com/evision.htm

damon

> Date: Mon, 5 Nov 2007 10:20:10 -0700
> From: [email protected]
> To: [email protected]
> Subject: Re: [EVDL] E-Gauge Peukert Correction question
>
> I ask this because it doesn't seem that the commercial E-meter does all of
> what I would like it to do. Nothing quite does. But I guess I don't need
> to collect all of the information all of the time.
>
> thanks,
> Brian
>
>>
>>
>>> It seems in my poor overcrowded memory, it was once talked about an
>>> open-source emeter. I have tried to find it in the archives, but
>>> have not had much luck. Does anyone remember this?
>>
>> It's been discussed, and a number of people have worked on them. It
>> seems that they discover it's a harder problem than they thought, so it
>> gets shelved, or only partially implemented, or becomes a commercial
>> product that is just as expensive as the E-meter.
>> --
>> Ring the bells that still can ring
>> Forget the perfect offering
>> There is a crack in everything
>> That's how the light gets in -- Leonard Cohen
>> --
>> Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
>>
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Discussion Starter #12
Damon, thanks for opinion,

Coming EVS23 prep pushed production back a bit, but you're
definitely getting yours ;-)

Regarding Peukert correction in EVision: there is provision for it
in software, but I decided not to implement it in (at least for
now) exactly due to unpredictability of driving and thus real
capacity left. Touch general pattern esp. in repetitive routs
can be established and so the average (over whole trip) consumption
rate. However, few will bother to find out real battery capacity,
without which there is nothing to apply the correction to.

In current EVision software a "usable "capacity" concept is
implemented. Assumption is, you're not suppose to discharge
lead battery very deep, ~50% DOD is good, and routine ~80% DOD
is getting close to early murdering it.

EVision just measures true energy (and capacity) *spent*, not left.
You declare how much of the battery capacity you consider usable
based on how far down you want to take it. If 1 hr rate capacity
is 80Ah and you in general want 50% DOD, no more you declare
(set in software) that 40Ah of the capacity is usable for driving,
so the other "spare" 50Ah are like not there. EVision will reset
to zero (100% SOC) after full charge and by the time precisely 40Ah
are taken out fuel gauge will come to zero SOC, saying to you
"empty", you've got to stop if you don't want to exceed 50% DOD
you yourself set up. Now, of course due to Peukert effect
whole capacity could of been 70Ah or 90Ah depending how
you drove, but that uncertainty is in remaining capacity, not
usable to you, so you wouldn't care [that much] if at 0% SOC
30Ah remains or 50Ah. What is important that you're guaranteed to
have 40Ah available to you for driving no matter now you're
going to drive. So continuous recalculation of MTE is far easier,
and you can set up the time constant to integrate consumption over.
Default is, I believe, 2 min. I noticed on mine that it's good for
more-less steady driving, but if it's stop-and-go (especially with
regen), you get to see 40 miles to empty one second, 160 miles next
second after good regen, 15 miles after hard acceleration on a long
ramp, and so on. So for such driving you set integration time to
6-8 min. This dampens peaks and smooths out the curve, but delays
filter response so you loose dynamics of the display. You pick
the compromise based on your taste for it and perceived usefulness.

Finally, getting SOC to 0% is not as scary because you know you
still have 50% (or whatever you declared) of battery capacity left,
so you can drive if you have to. (But you should not really
count on it! SOC meter will just remain on zero and amount of spent
Ah keep incrementing past 40Ah, so you know very precisely how many
you're actually extracting. What you don't quite know how much
remains, sort of gambling when your gas pointer reach zero for the
first time - you know there must be some gas reserve there by design,
but don't know for sure how much).

So, you're on your own going beyond chosen limit, meter can only
warn you when you reached it, but nothing can prevent you from
ignoring what it's telling you.

I talked to John Wayland about this concept, and he thinks such
implementation is better and more convenient than "messy" Peukert
adjustment. Well, you'll tell me once you start using the unit!

Victor

damon henry wrote:
> Have you checked out Victor's E-vision yet? He solicited a lot of
> input from this list first then went out and designed a beautiful new
> meter. Oh yeah, it costs even more than an E-meter :-( but that did
> not keep me from putting in an order for one. You find after doing
> this for a while that there are definitely things worth spending
> money on, and a great meter has made it up towards the top of my
> list.
>
> http://www.metricmind.com/evision.htm
>
> damon

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