# [EVDL] Battery opinion



## EVDL List (Jul 27, 2007)

Arent your batteries about a year old? What issues are you having?

-Jon Glauser
http://jonglauser.blogspot.com
http://www.evalbum.com/555





> SLPinfo.org <[email protected]> wrote:
> > The Universal Battery (12V, AGM; 110AH) model UB 121100 has been mentione=
> d a
> > couple of times on this list in passing, but I'm wondering if anyone who =
> ...


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## EVDL List (Jul 27, 2007)

Jon,

I've only had the car running since January but I think they had the
batteries sitting around for a while before they completed the
conversion. They = http://www.evequipmentsupply.com/

Several issues:

1. I have Group 31 (12V, 130 AH) RV/Marine batteries (yes, I know, poor
choice). Range is lousy - best I can get out of my 120V pack is 17 miles -
even then I can smell the batteries gassing pretty well. A big
contributor the problem here is also the really hilly terrain here in
Pocatello and I do lots of stop and go driving.

2. Huge voltage sag during acceleration (don't know how odd this is) - not
unusual, even being gentle on the accelerator, for voltage to sag from full
to 20% with the pack full and to well below 0% even with 70% charge left
(30% DOD).

3. Biggest issue is acid spillage. My Russco charger is very sensitive to
any kind of grounding and I've had bits of acid get on my metal battery tie
downs and it constantly trips the breaker on the charger. I've found that
the only way to avoid this is to literally take my entire pack apart once a
week and clean off all the batteries, the racks and the tie-downs. At 66
lbs each, taking the batteries in and out is taking a real toll on my back
and shoulders. Not crazy about the 2-3 hours this takes either.

Have taken some steps in the last few days - wrapped all my tie-downs in
triple layers of electrical tape, painted my racks with "rubber undercoat"
paint. Still waiting for the paint to dry so I don't know if this will
solve the problem.

But, as I've said here before, I'm not a tinkerer. I need something that
requires less hassle, so that's why I'm considering going to sealed
batteries. Will likely wait until this pack dies but ...


I really am interested in hearing if anyone has had good or bad experiences
with the Universal Battery UB 121100. I found a place where I can get them
for $165 each http://www.batteryconcepts.net/ which seems pretty decent.

Also if anyone can suggest a better AGM (that doesn't break the bank), I'd
like to hear about it too.

- Peter



> Jon Glauser <[email protected]> wrote:
> 
> > Arent your batteries about a year old? What issues are you having?
> >
> ...


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## EVDL List (Jul 27, 2007)

> SLPinfo.org wrote:
> 
> > 1. I have Group 31 (12V, 130 AH) RV/Marine batteries (yes, I know, poor
> > choice). Range is lousy - best I can get out of my 120V pack is 17 miles -
> ...


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## EVDL List (Jul 27, 2007)

Willie,

In principle with my current pack, 120V X 130 AH = 15.6 KwH of stored energy
but I don't know what % is usable. I have heard that with RV/Marine
batteries you probably shouldn't get more than 50-60% of that so that would
be 7.8-9.36 KwH. Interestingly now that I think about it, if you believe my
Kill-O-Watt meter, I have never put more than 9 KwH back into the batteries
during a full charge so that seems about right.

Don't know if I can follow your math (though I have no reason to doubt it;
it's just my poor math skills). My current batteries cost me about $100
each ($1000 total) and the AGMs (UB121100; 12V, 110 AH) are $165 each (about
$1900 with shipping). Don't know how to determine the usable energy in
AGMs however. That's partly why I'm asking if anyone has experience with
them or something similar.

I'd actually be very happy with 30 mile range. Bottom line however is that
$5500-$6500 for batteries alone definitely breaks the bank for me. I
realize that lithiums would last longer and potentially even be more cost
effective in the long run but I already took out a bank loan to do the
conversion I have. I have no intention of taking out another loan just for
batteries.

- Peter





> Willie McKemie <[email protected]> wrote:
> 
> > On Tue, May 19, 2009 at 01:09:21PM -0600, SLPinfo.org wrote:
> >
> ...


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## EVDL List (Jul 27, 2007)

> SLPinfo.org wrote:
> > Willie,
> >
> > In principle with my current pack, 120V X 130 AH = 15.6 KwH of stored energy
> ...


----------



## EVDL List (Jul 27, 2007)

> Rick Beebe wrote:
> > Lets assume the 120v wants to stay the same for performance reasons. The
> > 9KwH that you're actually using translates, roughly, to 120v x 75AH. If
> > we also assume lithium cells can be drawn down 80% we'd need 120v x 94AH
> ...


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## EVDL List (Jul 27, 2007)

Willie McKemie wrote: 

>


> Rick Beebe wrote:
> > >
> > > The 9KwH that you're actually using translates, roughly, to 120v x
> > > 75AH.
> ...


----------



## EVDL List (Jul 27, 2007)

Hey Peter,
> The Universal Battery (12V, AGM; 110AH) model UB 121100 has been mentioned a
> couple of times on this list in passing, but I'm wondering if anyone who has
> actually used them could share their experiences (good, bad or
> indifferent).
How much battery current do you need to accelerate and cruise? You may 
need to move your shunt to the battery loop to find this out.

I believe the UB121100's I have are sagging to 10.5V on 300A after only 
5-10% DoD (they're mostly broken in), but I'll get you more exact 
information soon.[1]

Cory Cross

[1] and if I forget, send me a private e-mail in a couple days


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## EVDL List (Jul 27, 2007)

Cory,

I only have access to motor current at the moment and am not inclined enough
to change to. My Logisystems controller is rated for up to 750 A but my
meter only reads to 500. There's so little flat ground in town that I'm not
sure what amp draw to say. On the few flat stretches at 35 mph I tend to
draw about 75 motor amps.

What are you driving and what range are you getting with your UB121100s?

Thanks to Willie for re-posting Lee' advise on batteries. Gels are tempting
but with all the hills keeping the amps low (and not annoying the rest of
the traffic) would be a big challenge.

- Peter



> Cory Cross <[email protected]> wrote:
> 
> > Hey Peter,
> > > The Universal Battery (12V, AGM; 110AH) model UB 121100 has been
> ...


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## EVDL List (Jul 27, 2007)

Hi Peter,
> What are you driving and what range are you getting with your UB121100s?
> 
2001 Blazer, but I haven't measured the range yet.

Cory

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## EVDL List (Jul 27, 2007)

>ThunderSky (TS) and Sky Energy (SE) both rate their cells at 0.3CA nominal
discharge current (i.e. 30A for a 
>90Ah cell). TS recommends a maximum of <=3CA (270A for a 90Ah cell)
"continuous", while SE recommends <=4CA 
>(360A for a 90Ah cell), but further states that "continuous" means for up
to 20 seconds.

No, TS cells can do 3C continuous (as in from full charge to dead).
Average voltage at 3C continuous is 2.8v.
http://www.aeva.asn.au/forums/forum_posts.asp?TID=980&PN=5 - mid way down
the page is testing of a TS40AH cell.


>I think the challenge with lower power cells such as the ThunderSky and Sky
Energy is that one ends up having to >use larger capacity cells than are
required to achieve the target range in order to have sufficient power 
>available.
For decent peak power output, this is absoltuely correct.

>As an extreme example of this, my own 120V car would have sufficient range
(and better than present) with just a >single string of 40Ah lithium cells,
but I too would have to buy at least 160Ah cells to be able to satisfy the
>450A maximum draws of my controller.

The 90AH cells can do 450A, for 10-20seconds.
If you need to do it continuously, then yes, 160AH is definitely required
(or higher rate batteries)

>Assuming a 40mph average speed, the vehicle appears to use about 15.3kW,
which is 127A @ 120V. This is about 2x >the manufacturer's 0.3CA
recommended typical discharge rate, so one might expect somewhat less cycle
life than 
>the spec sheet suggests.

Ive been getting a bit less cycle life than the spec sheet suggests, I
discharge at 1.4C continuous, 5C peak.
Though I have overdischarged 8 times (no load voltage below 2.5v), which I
suggest does more damage than the higher discharge rate.

Matt

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Roger Stockton
Sent: Wednesday, 20 May 2009 11:33 AM
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] Battery opinion

Willie McKemie wrote: 

>


> Rick Beebe wrote:
> > >
> > > The 9KwH that you're actually using translates, roughly, to 120v x
> > > 75AH.
> ...


----------



## EVDL List (Jul 27, 2007)

On Wed, May 20, 2009 at 04:54:16PM +0800, Matt Lacey wrote:
> Ive been getting a bit less cycle life than the spec sheet suggests, I
> discharge at 1.4C continuous, 5C peak.

Can you be more specific on observed cycle life? I understand that 
there a quite a few TS-LPF90 packs that have been running around "down 
under" for several years.

-- 
Willie, ONWARD! Through the fog!
http://counter.li.org Linux registered user #228836 since 1995
Debian3.1/GNU/Linux system uptime 522 days 7 min minutes

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## EVDL List (Jul 27, 2007)

> Willie McKemie wrote:
> > I haven't done much thinking about how one might configure a lead
> > equivalent lithum pack, but I was thinking ~96v of lithium might be
> > closer to 120v of lead, since the lead is likely to have a lot more
> ...


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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> >
> > > I think 100ah cells are about the smallest that should be used in
> > > a car.
> ...


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## EVDL List (Jul 27, 2007)

Thank you all! This thread is a keeper for me...pasting into my "EV
Tracker" document.

Some of this "ah" and "c" stuff is starting to make sense. I think I'm
almost to the point where I have a recipe for batteries/controller/motor
that "will work" for my project. Might not be the absolute best, but good
bang for the buck and also fits the general goals for the vehicle.

Brett



> Willie McKemie <[email protected]> wrote:
> 
> > On Wed, May 20, 2009 at 08:24:14AM -0500, Lee Hart wrote:
> > >
> ...


----------



## EVDL List (Jul 27, 2007)

>Can you be more specific on observed cycle life? I understand that there a
quite a few TS-LPF90 packs that have 
>been running around "down under" for several years.

My cells are 40AH, but same construction as the 90AH cells.
Ive done 8-900 cycles to 40%dod (assuming dpth is referenced to original
capacity).
Ive done 20'000km, and my original range to 80% was 40km (now its 35km)
My pack was put into service Jan 2008 (so now 16 months old)
Present capcity is ~85% of original, where if the data sheet is true, and I
stuck to it I should still have 90%+ capacity remaining.

I suspect the capacity loss was more due to the 8 overdischarge events than
the higher continuous current.
Though to know for sure another pack would have to be tested, but subject to
the high currents only (im sure someone out there will do it just through
daily use as I have).

It's a shame I don't have a way to (easily) do a controlled discharge of the
pack every few months to log capacity degredation.


Matt

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Willie McKemie
Sent: Wednesday, 20 May 2009 7:13 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Battery opinion

On Wed, May 20, 2009 at 04:54:16PM +0800, Matt Lacey wrote:
> Ive been getting a bit less cycle life than the spec sheet suggests, I 
> discharge at 1.4C continuous, 5C peak.

Can you be more specific on observed cycle life? I understand that there a
quite a few TS-LPF90 packs that have been running around "down under" for
several years.

--
Willie, ONWARD! Through the fog!
http://counter.li.org Linux registered user #228836 since 1995
Debian3.1/GNU/Linux system uptime 522 days 7 min minutes

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## EVDL List (Jul 27, 2007)

> Matt Lacey wrote:
> 
> > No, TS cells can do 3C continuous (as in from full charge to dead).
> 
> ...


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## EVDL List (Jul 27, 2007)

>No, you miss the distinction between what the cells "can do" and what the
manufacturer recommends. ;^>

Point taken, kinda like how I run my "1500w" hub motor at 2800w continuous,
9000w peak 

>How are you determining range to 80% [DOD], or that the present capacity is
~85% of original?

Every so often I go on a longer than usual trip. Occasionally one (actually
its more like most) of the cells will sag below 2.5v when im drawing around
40A (reduced pack voltage lowers my top speed as well as continuous current
draw).

Its at this point I read my cycleanalyst (really good AH counter) and take
that to be 100%dod.

My daily ride to work takes 10-13AH depending on conditions. 
16AH is the average discharge on each use, based on 2 x 2000km strethes
where I actively logged distances travelled and energy usage.

>He narrowed the range to comething like 2.8V and 4.0V, which TS literature
predicted would reduce the available
>capacity to about 75% of nameplate.

The difference if recoverable charge between charging to 4.2v and chargign
to 3.4v I measured to be 0.75AH on a 40AH cell. I measured this when I bench
tested a cell.

I don't recall the difference in capacity between discharging to 2.8v and
2.5v, (and I can't find the data logs, though I could repeat the test).

I charge to 3.6xv. My BMS balances the cells to within 0.05v of each other.

>Can you provide a link to the datasheet you refer to that predicts what
capacity you should have after X cycles?

The datasheet im referring to is the standard TS cell datasheet.
At 2000 cycles it states >80% capacity remaining and at 3000 cycles >70%
capacity remaining.

Assuming that most damage in the specified charge/discharge regimen is done
at the end of charge, and the capacity loss is linear, I would expect to
still have more than 90% capacity remaining.

In reality, I discharge 4-5x faster than rated, discharge far enough that no
load voltage is below 2.5v on 8 occasions and charge to a lower than rated
voltage.

More recently, im allowing cell voltage to sag to 2.1v (cell average), with
some going below 1.5v, to see if cell degredation increases measurably.
Aside from the increased performance, im doing this because in a couple of
years we will have access to many more data points with similar levels of
abuse to my own.
I know of only a couple of people who are presently allowing this much
voltage sag.

(TS 40AH and 60AH cells are now original equipment for a couple of the more
popular chinese scooters, some of which put out 5kw, with only 20 cells).


Matt

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Roger Stockton
Sent: Thursday, 21 May 2009 11:35 PM
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] Battery opinion



> Matt Lacey wrote:
> 
> > No, TS cells can do 3C continuous (as in from full charge to dead).
> 
> ...


----------



## EVDL List (Jul 27, 2007)

> Roger Stockton wrote:
> >
> > I would be hesitant to discharge the cells continuously at this
> > rate even with 160Ah cells. My concern is that part of what I am
> ...


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## EVDL List (Jul 27, 2007)

You forgot about the lower electrical energy consumption of lithium 
over lead.

However, to be totally fair in any ecconomic comparison you need to do 
a present worth analysis.



Sent from my iPhone



> Willie McKemie <[email protected]> wrote:
> 
> > On Thu, May 21, 2009 at 08:35:19AM -0700, Roger Stockton wrote:
> >>
> ...


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## EVDL List (Jul 27, 2007)

> Matt Lacey wrote:
> 
> > Point taken, kinda like how I run my "1500w" hub motor at
> > 2800w continuous, 9000w peak
> ...


----------



## EVDL List (Jul 27, 2007)

> Roger Heuckeroth wrote:
> > You forgot about the lower electrical energy consumption of lithium
> > over lead.
> 
> ...


----------



## EVDL List (Jul 27, 2007)

> Roger Heuckeroth wrote:
> >> You forgot about the lower electrical energy consumption of lithium
> >> over lead.
> 
> ...


----------



## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> 
> > So, the charge efficiency of a lithium pack with BMS is essentially the
> > same as a lead-acid pack without BMS.
> ...


----------



## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> 
> > Roger Heuckeroth wrote:
> >>> You forgot about the lower electrical energy consumption of lithium
> ...


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## EVDL List (Jul 27, 2007)

"because we always overcharge lead-acids to equalize them."
I was told by Trojan to never EQ their AGM batteries. 
As it would cause venting.
Are they wrong?
Neal



> Lee Hart wrote:
> >
> > Roger Heuckeroth wrote:
> >>> You forgot about the lower electrical energy consumption of lithium
> ...


----------



## EVDL List (Jul 27, 2007)

They are correct in saying that balancing by over-charging reduces service
life (relative to using a BMS, or using a battery by itself, and not in a
pack)

With AGMs, once the water is lost to gas, you can never get it back.
So the damage is more apparent for AGMs, than floodeds where the water can
be replenished, and not the limiting factor in terms of service life.

Matt 

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of shred
Sent: Saturday, 23 May 2009 12:55 AM
To: [email protected]
Subject: Re: [EVDL] Battery opinion


"because we always overcharge lead-acids to equalize them."
I was told by Trojan to never EQ their AGM batteries. 
As it would cause venting.
Are they wrong?
Neal



> Lee Hart wrote:
> >
> > Roger Heuckeroth wrote:
> >>> You forgot about the lower electrical energy consumption of lithium
> ...


----------



## EVDL List (Jul 27, 2007)

>So, the charge efficiency of a lithium pack with BMS is essentially the
same as a lead-acid pack without BMS.

In general, for specific applications, this can be either proved true or
false.

The *most* efficient Lithium setup is more efficient than the *most*
efficient lead acid setup, just in terms of energy in vs energy out.

This is mainly due to the lack of secondary reactions in the course of
normal operation for a lithium battery.
So the only losses are:
Series resistance loss
Shunt resistance loss (self discharge)
BMS power requirement

A lead acid pack has the above (except maybe the BMS, depending on the pack)
as well as loss to secondary reactions (mainly gassing, unless there is tiem
to charge at a voltage low enough that this doesn't happen, and a BMS that
allows another form of balancing)

The greatest difference in lost energy between a lead acid pack and a
lihtium pack will be when it comes to balancing.

The BMS balancing action only has to keep up with the difference between the
cell that has the fastest self discharge, and the slowest.

Balancing by overcharge (for lead acid) isn't all that precise, unless
coupled with a per cell voltage monitoring arrangement, and a way for
automatic shut down of the charger (the same thing a lithium BMS does).

The other (less efficient, less precise, cheaper, simpler way) is to
overcharge by a fixed # of AH every so often

If the power lost to run each BMS cell module is the same for the lead acid
BMS and the lithium BMS, then the lead acid version would require more power
due to the greater number of cells. Other assumptions made were:

AH variation on each charge for lead acid and lithium packs are the same (a
greater number of cells has a higher probability of greater variation)
The balancing action consumes no power while in the *off* state (I know of
no such mechanism where this is not the case)
Internal (both series and shunt) resistance for the whole pack for both
lithium and lead are the same
Both packs have the same nominal voltage.

Matt


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Lee Hart
Sent: Friday, 22 May 2009 11:47 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Battery opinion



> Roger Heuckeroth wrote:
> >> You forgot about the lower electrical energy consumption of lithium
> >> over lead.
> 
> ...


----------



## EVDL List (Jul 27, 2007)

>> So, the charge efficiency of a lithium pack with BMS is essentially
>> the same as a lead-acid pack without BMS.



> Matt Lacey wrote:
> > In general, for specific applications, this can be either proved true or
> > false.
> 
> ...


----------



## EVDL List (Jul 27, 2007)

> shred wrote:
> > "because we always overcharge lead-acids to equalize them."
> > I was told by Trojan to never EQ their AGM batteries.
> > As it would cause venting.
> ...


----------



## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> >> essentially all lithium cell applications have a BMS that uses
> >> shunt regulators to balance them. These shunt regulators burn up
> >> the excess charging energy as heat, which lowers the system
> ...


----------



## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> 
> >>
> >> however, equalization is not the only area where they are more
> ...


----------



## EVDL List (Jul 27, 2007)

----- Original Message ----- 
From: "Roger Heuckeroth" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Saturday, May 23, 2009 9:46 PM
Subject: Re: [EVDL] Battery opinion


>
>


> Lee Hart wrote:
> >
> >>>
> >>> however, equalization is not the only area where they are more
> ...


----------



## EVDL List (Jul 27, 2007)

> Roger Heuckeroth wrote:
> >>> A Lithium pack is lighter than an equal usable energy lead pack
> >>> by a factor of three, or so. This results in a lower watts per
> >>> mile. Especially on hilly terrain, or in stop and go traffic. I
> ...


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## EVDL List (Jul 27, 2007)

Awesome comparison example Lee..thanks.


> In other words, it takes *more* power to move this car with the lighter
lithium pack. You gained 7.5% by reducing the weight, but lost 9% 
because the smaller pack has more internal resistance.

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## EVDL List (Jul 27, 2007)

Thanks Bob-

You raise the points that concern me most in considering the extra cost to
go Lithium.
We just don't know how long these will actually last.
And we don't know how they'll behave over time with the other
variables--temperature, vibration, etc.
Increased cycle life doesn't justify the cost if one mistake causes the
cycle life to go to zero or if cycles per year are small or if weight or
space savings just don't translate into benefits. Such is the case for my
EV's: electric boat and antique electric car.
Neither gets much use...long cycle life on batteries means nothing when
chg/dischg cycles per year is well under 100.
Do we expect that the Lithium batteries being made in China now will last
20yrs or longer? 10yrs? 5yrs?
What are they guaranteed for---1 or 2yrs is it, right? Or is there any
guarantee at all?
So cycle life claims mean little unless you expect heavy use and/or expect
these will really last 10yrs or more.
In my case, I'll consider investing in a string of these at some point, but
I want to have some confidence that they'll last a long time first.
I'm not an early adopter.

-Myles Twete, Portland, O.

1920 Milburn Light Electric Model 27L: www.evalbum.com/348
The Reach Of Tide electric Columbia river barge cruiser: www.evalbum.com/492


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Bob Rice
Sent: Saturday, May 23, 2009 8:57 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Battery opinion


----- Original Message ----- 
From: "Roger Heuckeroth" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Saturday, May 23, 2009 9:46 PM
Subject: Re: [EVDL] Battery opinion


>
>


> Lee Hart wrote:
> >
> >>>
> >>> however, equalization is not the only area where they are more
> ...


----------



## EVDL List (Jul 27, 2007)

Lee,
Replace "Resistance loss" by plain "Resistance" in your last 
comparison (since aerodynamics are unchanged) and I completely agree.
Regards,

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 magicJack: +1 408 844 3932
Tel: +91 (040)23117400 x203 XoIP: +31877841130

Please consider the environment before printing this e-mail.
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Lee Hart
Sent: Sunday, May 24, 2009 9:34 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Battery opinion



> Roger Heuckeroth wrote:
> >>> A Lithium pack is lighter than an equal usable energy lead pack
> >>> by a factor of three, or so. This results in a lower watts per
> >>> mile. Especially on hilly terrain, or in stop and go traffic. I
> ...


----------



## EVDL List (Jul 27, 2007)

Hey guys,

Not to be a pain but I started this thread and I've still not had my
original question answered (one person did comment). Anybody have "real
world" experience with the Universal Battery UB 121100 (12V, 110 AH)?
Would you recommend it or not compared to other 12V AGMs?

Peter Flipsen Jr
http://www.evalbum.com/1974
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## EVDL List (Jul 27, 2007)

Concorde says to never equalize their AGM's. I have three sets of four in parallel (24 VDC as part of a PV system) and have never equalized them (had them about 6 years now.) They remain *very* close i.e. less than .05 volt difference in resting state. Lee, did you ever equalize the Concordes you had in your EV?

Frank




________________________________
From: Lee Hart <[email protected]>
To: Electric Vehicle Discussion List <[email protected]>
Sent: Saturday, May 23, 2009 12:13:33 PM
Subject: Re: [EVDL] Battery opinion



> shred wrote:
> > "because we always overcharge lead-acids to equalize them."
> > I was told by Trojan to never EQ their AGM batteries.
> > As it would cause venting.
> ...


----------



## EVDL List (Jul 27, 2007)

Very nice analysis Lee. However, the "hidden" assumption is that the PbA pack holds enough energy to satisfy the driver's needs. Under this condition the lead pack works fine and there would be little reason to consider lithium unless the driver/owner believes the lithium life-cycle claims and plans to keep the vehicle long enough to benefit from it.

But the packs aren't equal. Not only is the lithium pack lighter, you can use it harder. What's the range of the lead pack? 12 kWh nominal ~ 6-7 kWh at EV current levels. Using 75% of that means maybe 16-20 miles. The lithium pack could probably provide 45-50 miles range. Carrying enough lead for longer range in a light-weight car might push the vehicle over the weight limit i.e. a show-stopper where lithium will allow a safer conversion. Throw in some hills, stops and starts, etc. and the scale tips even more towards lithium.

The take-away for me has always been that it's important to understand your needs and design accordingly. My pickup conversion uses PbA and does what I need it to do here in the rolling countryside of coastal Maine. I'm presently working on another motorcycle conversion that will use lithium because I want greater range and performance.




________________________________
From: Lee Hart <[email protected]>
To: Electric Vehicle Discussion List <[email protected]>
Sent: Sunday, May 24, 2009 12:04:11 PM
Subject: Re: [EVDL] Battery opinion

<<<Yes, we do! For one thing, batteries have internal resistance. If you 
try to use 1/3rd the batteries to hold range constant and reduce weight, 
now you have 3 times the internal resistance (and associated losses). 
The losses from the extra internal resistance can easily exceed the 
benefits from the reduced weight.

Case 1:
- Car with ten 12v 100ah 60 lbs lead-acid batteries
- 2000 lbs car + 600 lbs pack = 2600 lbs
- Power consumption: 120v @ 125a = 15kw at 60 mph (250wh/mile)
- Battery pack resistance: 10 x 0.005 ohm = 0.05 ohms
- Battery power loss at 125a: P = I^2R = 781 watts (5% of 15kw)
- 15000w to move car + 781w lost in batteries = 15,781w from batteries

Case 2:
- Same car with 33 x 3.6v 100ah 6 lbs lithium cells
- 2000 lbs car + 200 lbs pack = 2200 lbs (15% lighter)
- Power consumption: Rolling resistance drops 15% (proportional to
weight reduction). Wind resistance (which usually dominates) is
unchanged by weight. We'll be charitable and say rolling resistance
loss is equal to wind resistance loss, so power consumption drops
by half of the 15% due to the weight reduction.
15kw - 7.5% = 13.875kw = 120v @ 115a at 60 mph (231 wh/mile)
- Battery pack resistance: 33 x 0.0045ohms = 0.15 ohms
- Battery power loss at 115a: P = I^2R = 1984 watts (14% of 13.875kw)
- 13875w to move car + 1984w lost in batteries = 15,859w from batteries

In other words, it takes *more* power to move this car with the lighter 
lithium pack. You gained 7.5% by reducing the weight, but lost 9% 
because the smaller pack has more internal resistance.

The key point to take away is that the differences are *small*. I 
assumed a typical EV, with average batteries of both types -- and there 
is very little difference. I could have changed the results by assuming 
a particularly bad lead-acid pack, or particularly good lithiums; or by 
using a very efficient (or inefficient) car, or some extreme driving 
schedule (like driving uphill at 10 mph so wind resistance is 
negligible, etc.)>>>>



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## EVDL List (Jul 27, 2007)

I've had three of them for a couple of years in a small m-cycle conversion. They work okay for me but I have no experience with other AGM's. Have you looked in the evalbum? Maybe Cor will chime in as I think he may have used some.




________________________________
From: SLPinfo.org <[email protected]>
To: Electric Vehicle Discussion List <[email protected]>
Sent: Monday, May 25, 2009 12:38:30 PM
Subject: Re: [EVDL] Battery opinion

Hey guys,

Not to be a pain but I started this thread and I've still not had my
original question answered (one person did comment). Anybody have "real
world" experience with the Universal Battery UB 121100 (12V, 110 AH)?
Would you recommend it or not compared to other 12V AGMs?

Peter Flipsen Jr
http://www.evalbum.com/1974
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## EVDL List (Jul 27, 2007)

I think Cor Van der Water has used Universal brand batteries in a truck, so 
he may be able to report on their performance. Chris Zach has just recent 
fitted them to his US Electricar.

David Roden - Akron, Ohio, USA
EVDL Administrator

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## EVDL List (Jul 27, 2007)

>
>> I don't think we need any testing to conclude that a more energy
>> dense battery beats a less energy dense battery in energy efficiency
>> alone.
>
> Yes, we do! For one thing, batteries have internal resistance. If you
> try to use 1/3rd the batteries to hold range constant and reduce 
> weight,
> now you have 3 times the internal resistance (and associated losses).
> The losses from the extra internal resistance can easily exceed the
> benefits from the reduced weight.
>
> Case 1:
> - Car with ten 12v 100ah 60 lbs lead-acid batteries
> - 2000 lbs car + 600 lbs pack = 2600 lbs
> - Power consumption: 120v @ 125a = 15kw at 60 mph (250wh/mile)
> - Battery pack resistance: 10 x 0.005 ohm = 0.05 ohms
> - Battery power loss at 125a: P = I^2R = 781 watts (5% of 15kw)
> - 15000w to move car + 781w lost in batteries = 15,781w from 
> batteries
>
> Case 2:
> - Same car with 33 x 3.6v 100ah 6 lbs lithium cells
> - 2000 lbs car + 200 lbs pack = 2200 lbs (15% lighter)
> - Power consumption: Rolling resistance drops 15% (proportional to
> weight reduction). Wind resistance (which usually dominates) is
> unchanged by weight. We'll be charitable and say rolling resistance
> loss is equal to wind resistance loss, so power consumption drops
> by half of the 15% due to the weight reduction.
> 15kw - 7.5% = 13.875kw = 120v @ 115a at 60 mph (231 wh/mile)
> - Battery pack resistance: 33 x 0.0045ohms = 0.15 ohms
> - Battery power loss at 115a: P = I^2R = 1984 watts (14% of 13.875kw)
> - 13875w to move car + 1984w lost in batteries = 15,859w from 
> batteries
>
> In other words, it takes *more* power to move this car with the 
> lighter
> lithium pack. You gained 7.5% by reducing the weight, but lost 9%
> because the smaller pack has more internal resistance.
>
> The key point to take away is that the differences are *small*. I
> assumed a typical EV, with average batteries of both types -- and 
> there
> is very little difference. I could have changed the results by 
> assuming
> a particularly bad lead-acid pack, or particularly good lithiums; or 
> by
> using a very efficient (or inefficient) car, or some extreme driving
> schedule (like driving uphill at 10 mph so wind resistance is
> negligible, etc.)

Lee,

The advise you give to this online community is top notch, however, 
the above comparison is very biased towards making and defending your 
point. For instance:

1. You allow for a reduction in rolling resistance, but totally 
discount the extra energy it takes to accelerate that additional 400 
lbs up to speed, and to go through normal stop and go traffic. I live 
in a very rural area, but even so, to go to the local grocery store I 
have to accelerate from a stop six times in 5 miles even assuming no 
traffic, just stop signs and lights.

2. The internal resistance of most of the 100 Ah cells that I am 
familiar with are rated at <2 mohms. I don't know if that is 
accurate, or if that changes with load, but the 100 Ah cell from Ecity 
that I tested had very little temperature rise at 1C continuous load. 
Energy lost to internal resistance is in the form or heat, correct. 
If 14% of the energy in the cell was lost to heat that would have been 
approximately 43 watts. I can tell you for sure that if there was the 
equivalent heat of a 40 watt light bulb being generated in the cell, 
the temperature rise would have been much greater. I'm just going by 
my sense of proportion. My son has a lava lamp that has a 25 watt 
bulb in it. The whole lamp gets too hot to touch within 30 minutes, 
and it weighs about the same as the Ecity cell. After 1:10 of 1C 
continuous discharge the cell got up to 82 deg (68 degree room 
temperature). I know this comparison is not apple for apples, but I 
highly doubt 86% energy efficiency.

To be fair, I have no idea how other cells compare, since I have only 
tested the Ecity cell.

3. It was my impression that the internal resistance of lead acid 
batteries goes up substantially as they decrease in SOC. In the Ecity 
cell I tested the voltage stayed just about flat to 80% DOD indicating 
not much change in internal resistance. How do you figure that into 
the above?


Roger

PS. I hope you don't take my challenging you as a any form of insult. 
I have nothing but respect for you. They say a good student never 
just accepts what his teacher says.

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## EVDL List (Jul 27, 2007)

> Myles Twete wrote:
> 
> > Thanks Bob-
> >
> ...


----------



## EVDL List (Jul 27, 2007)

> Roger Heuckeroth wrote:
> > Lee,
> >
> > The advise you give to this online community is top notch, however,
> ...


----------



## EVDL List (Jul 27, 2007)

> In this situation, my hypothesis is: "For the average EV, switching from
> a lead-acid pack to a lithium pack 1/3rd the weight will have less than
> a 10% effect on your range and acceleration".

All I can say is, this discussion happens NOW?
AFTER I make a deposit ?

(I know, it's been discussed before but maybe not this much 

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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> 
> > Roger Heuckeroth wrote:
> >
> ...


----------



## EVDL List (Jul 27, 2007)

> Seth Rothenberg wrote:
> > > In this situation, my hypothesis is: "For the average EV, switching from
> > > a lead-acid pack to a lithium pack 1/3rd the weight will have less than
> > > a 10% effect on your range and acceleration".
> ...


----------



## EVDL List (Jul 27, 2007)

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----------



## EVDL List (Jul 27, 2007)

> Seth Rothenberg wrote:
> 
> >> In this situation, my hypothesis is: "For the average EV, switching
> >> from
> ...


----------



## EVDL List (Jul 27, 2007)

Willie, Roger,
Thanks - you have reconciled the two opinions...
My goal is to keep weight constant (GVWR - 350),
while increasing range hopefully to do a round trip
to/from work.

Thanks
Seth

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## EVDL List (Jul 27, 2007)

I doubt the veracity of these numbers - 10% is pretty insignificant, and 
I've seen more increase than that; these numbers don't add up at all!!

Joseph H. Strubhar

Web: www.gremcoinc.com

E-mail: [email protected]
----- Original Message ----- 
From: "Seth Rothenberg" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Tuesday, May 26, 2009 6:48 AM
Subject: Re: [EVDL] Battery opinion


>> In this situation, my hypothesis is: "For the average EV, switching from
>> a lead-acid pack to a lithium pack 1/3rd the weight will have less than
>> a 10% effect on your range and acceleration".
>
> All I can say is, this discussion happens NOW?
> AFTER I make a deposit ?
>
> (I know, it's been discussed before but maybe not this much 
>
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## EVDL List (Jul 27, 2007)

>> In this situation, my hypothesis is: "For the average EV, switching from
>> a lead-acid pack to a lithium pack 1/3rd the weight will have less than
>> a 10% effect on your range and acceleration".



> Seth Rothenberg wrote:
> > All I can say is, this discussion happens NOW? AFTER I made a deposit?
> 
> Reality always trumps theory. If you already ordered your batteries,
> ...


----------



## EVDL List (Jul 27, 2007)

Remember the argument is not really relevant for most lead-to-lithium
swaps. For example, I replaced my planned lead battery with a lithium
battery of the /same/ weight, so my range increases dramatically. My
acceleration actually goes down somewhat because I planned a small low
internal resistance AGM pack while my actual lithium battery is a small
high internal resistance Thunder Sky pack.

So, I'm doing the swap but I'm keeping the weight the same and replacing
a high performance lead battery with a medium to low performance lithium
battery. My change and also my results are dramatically different from
Lee's hypothesis. Also, I never bought the lead pack so I'm guessing a
little about it's power output.

Some real world data: my 54kg Thunder Sky LiFePO4 battery will do 20kW
for a few seconds (when it's at 25C, less now it's winter here). When
I'm finished, I will have about 150kg of these cells in the car, but
that's in the future.



> joe wrote:
> > I doubt the veracity of these numbers - 10% is pretty insignificant, and
> > I've seen more increase than that; these numbers don't add up at all!!
> >
> ...


----------



## EVDL List (Jul 27, 2007)

> Roger Heuckeroth wrote:
> > I guess this illustrates how important internal resistance really is
> > when selecting a battery. It rarely come up directly in these
> > discussions. We talk more about voltage sag at load which is related
> ...


----------



## EVDL List (Jul 27, 2007)

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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> 
> >>>
> >>> What does the Ecity data sheet claim for its internal resistance?
> ...


----------



## EVDL List (Jul 27, 2007)

Hi Peter,

Yes - I and a few others have used this battery in their
US Electricar trucks and I know of some other EVs also.
Before buying I tested two batteries to actually deliver
almost 80 Ah at 1C discharge, which is according to their
claim and pretty good for an AGM battery of 110 Ah.
However I have been charging them too sparingly (undercharge)
resulting in badly balanced cells after many thousands miles
and consequently reversing some cells after some longer drives.
(I used one string of 26 batteries for 312V pack and drove my
S10 over 60 miles on a charge several times, until the pack 
started sagging too much on the last freeway miles before
getting home, due to reversed cells)
In t he end I did get almost 10k miles out of them, not as
many as I expected but this was my first pack and we all
know that you murder the first pack one way or the other.
Others have easily gotten well beyond 10k though I never
heard how many exactly - even without balancers - by always
charging before the SOC hit 50%, but I sold my truck a year
ago and have little time to follow all discussions, that is
why I missed your initial request.

I would still recommend this battery especially if you want/need
sealed batteries for a decent price.
My recommendations:
- buy direct from the manufacturer UPG in Texas, especially if
you can find one or two other EV'ers who need batteries, as
you will get dealer prices by signing up with them.
- overcharge (equalize) them carefully instead of under-charge
to give the best performance (You do not need to cook them
or equalize every charge cycle, but make sure that they very
regularly get equalized to keep the cells in each battery in
line, even if you have regulators
- preferably use simple regulators like the zener-regs from Lee.
again, make sure that the regs have enough time to work and
equalize, do not always shut the charger off as soon as you
see all regs light up!

Prices probably have changed a lot, I do not know how competitive
they still are. When I bought my pack of 26 I payed just over
$2k now 4 years ago.

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected]xxx Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 magicJack: +1 408 844 3932
Tel: +91 (040)23117400 x203 XoIP: +31877841130

Please consider the environment before printing this e-mail.
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of SLPinfo.org
Sent: Monday, May 25, 2009 10:09 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Battery opinion

Hey guys,

Not to be a pain but I started this thread and I've still not had my
original question answered (one person did comment). Anybody have "real
world" experience with the Universal Battery UB 121100 (12V, 110 AH)?
Would you recommend it or not compared to other 12V AGMs?

Peter Flipsen Jr
http://www.evalbum.com/1974
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## EVDL List (Jul 27, 2007)

Cor,

Thanks for your detailed input. As always it is appreciated. I am quite
ready for sealed batteries as my current 12V RV/Marine batteries have been
giving me nothing but grief with acid mist getting on my battery tie downs
and grounding out my Russco charger - I've had someone tell me that the GFCI
is too sensitive (intended for household use (trips at 20 ma) when a hot tub
type (trips at 50 ma) might be more appropriate). But fixng the problem with
my current setup means totally disassembling my battery pack. My back and
shoulders are starting to suffer as I've had to do it once a week.

I've been so focused on that problem for the past several weeks that I
haven't been checking individual battery voltages. When I did this weekend
I realized that I may now have two dead batteries (both registered 10.80 V
after a full charge). I checked the SG on one and one cell reads about 50%
(1.200) and one reads 0% (1.120). Needless to say I'm ready for a change.
I got the car on the road in January but the batteries are dated Aug and
Sept 2008. That means that, consistent with what some on the list
predicted, they won't make it a year.

Since asking about the Universal AGMs I've re-read Lee Hart's advise on
battery choice. I have modified my driving approach recently (I now start
out in 1st gear) and as a result my motor amp draw is consistently much
lower than it was (I still have not switched my amp meter to read battery
amps). In the process I'm now wondering if I wouldn't be better off with
Gels because of their longer life (if amp draw is kept relatively low).
Cost is a huge issue for me; I'm still making payments on the loan I took
out for the conversion. Anyway, I've started to lean toward the Deka
Dominator.

Clearly I would need a BMS for whichever I choose - I recently got some
zener regulators that I could use, I could get a Pak Traker setup, and my
Russco charger allows me to easily adjust the finishing voltage (it's not
temp regulated but I can adjust it manually). And of course I'd want to use
your very helpful diagram to be able to read battery amps while driving.

Will give it some more thought. Thanks again.

- Peter Flipsen Jr
http://www.evalbum.com/1974






> Cor van de Water <[email protected]>wrote:
> 
> > Hi Peter,
> >
> ...


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## EVDL List (Jul 27, 2007)

> SLPinfo.org wrote:
> > - Peter Flipsen Jr
> > http://www.evalbum.com/1974
> 
> ...


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## EVDL List (Jul 27, 2007)

I realize that drag may not be a big thing at low speeds but I figure every
little bit helps.

- Peter



> Willie McKemie <[email protected]> wrote:
> 
> > On Tue, May 26, 2009 at 11:35:18PM -0600, SLPinfo.org wrote:
> > > - Peter Flipsen Jr
> ...


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## EVDL List (Jul 27, 2007)

>> This is mainly due to the lack of secondary reactions in the course of 
>> normal operation for a lithium battery.

>This can also be true for certain types of lead-acids. For example, the
Gates/GE/Hawker/Enersys Cyclon gel cells >use pure lead plates, and have a
coulometric charge efficiency so close to 100% that it is difficult to
measure.

Finally got around to replying to this.

I stand corrected.
Do the impurities found in most other lead acid batteries serve a particular
purpose?
Is there any negative to their elimination? (internal resistance, max
discharge rate, service life, weight, etc?)

Matt

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Lee Hart
Sent: Saturday, 23 May 2009 5:20 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Battery opinion

>> So, the charge efficiency of a lithium pack with BMS is essentially 
>> the same as a lead-acid pack without BMS.



> Matt Lacey wrote:
> > In general, for specific applications, this can be either proved true
> > or false.
> 
> ...


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## EVDL List (Jul 27, 2007)

> Matt Lacey wrote:
> > Do the impurities found in most other lead acid batteries serve a
> > particular purpose? Is there any negative to their elimination?
> > (internal resistance, max discharge rate, service life, weight, etc?)
> ...


----------



## EVDL List (Jul 27, 2007)

> SLPinfo.org wrote:
> > my current 12V RV/Marine batteries have been giving me nothing but
> > grief with acid mist getting on my battery tie downs and grounding
> > out my Russco charger - I've had someone tell me that the GFCI is too
> ...


----------



## EVDL List (Jul 27, 2007)

> Roger Heuckeroth wrote:
> > Here are two data points from my tests both taken at 50% SOC point.
> > R = (3.09-2.94)/ (200.5-99.2) = 0.0015 ohms.
> > at 50% SOC between 2C and 3C it yields Ri of 1.2 mohm.
> ...


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## EVDL List (Jul 27, 2007)

> Frank John wrote:
> > Concorde says to never equalize their AGM's. I have three sets of
> > four in parallel (24 VDC as part of a PV system) and have never
> > equalized them (had them about 6 years now.) They remain *very*
> ...


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