# [EVDL] Charger Temperature Compensation



## EVDL List (Jul 27, 2007)

I broke down and bought a Quickcharge automatic charger. It was
reasonably priced (relatively) and is beautifully constructed. A huge
transformer makes it quite heavy. It seems to be charging perfectly
for 75 degree temperatures. This means it is undercharging for the 20
degree weather we are experiencing now. It is non adjustable. I have
been in discussion with the very receptive manufacturer about
solutions to raising the voltage for cold weather operation.

My question is, how much actual difference would the correct charge
make? Would enough extra amp hours go into the pack to affect my hard
hit range? I would hate to hassle over a half mile increase. 5 miles
would be worth a good deal of effort. Last summer's 30 mile range is
down to 16. I am well aware that there are a number of reasons for
this, only one of which is the charger. Anyone have a guess as to how
much I am losing at 20 degrees by charging as though it was 75?

-- 
http://www.austinev.org/evalbum/1059
http://stormselectric.blogspot.com/
Storm

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## EVDL List (Jul 27, 2007)

I've used that charger before. I'm guessing that the only way to get
the extra amp-hours into the battery is to extend the equalize time.
The voltage might not be high enough though, I dont remember the exact
method they equalize with.

The problem is not so much just low voltage. I was seeing that there
was a net loss of amp-hours (on a link-10). After the first day, only
a little, but after several days it added up to a large deficit. I
dont know if this is meaningless however. I hope someone else can
speak on the issue.

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

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## EVDL List (Jul 27, 2007)

I purchased the QuickCharge as well. Their website says "We've also added
ambient temperature sensing for more precise float voltage." I assumed that
meant you don't need to worry about temperature compensation. Does your
model not have temperature compensation?

The question that I have been wondering about is how to do an equalization
charge with the QuickCharge. It doesn't seem that there is any way to
raise the voltage for an equalization charge occasionally.

Steve
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## EVDL List (Jul 27, 2007)

The word I got is that they can reduce the charge for high temp to
avoid overcharging. Apparently the max voltage is set by the
transformer. You will note less than .5 amps is going in when the
charger indicates over 95% charged. The voltage holds steady at 187.2
after 80% charged.



> Steve Skarda <[email protected]> wrote:
> > I purchased the QuickCharge as well. Their website says "We've also added
> > ambient temperature sensing for more precise float voltage." I assumed that
> > meant you don't need to worry about temperature compensation. Does your
> ...


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## EVDL List (Jul 27, 2007)

I'd be concerned that they are monitoring "ambient" temperature and not
battery temperature. I'm just guessing, but I'd bet most people don't have
their charger packed in with the batteries and that there will be a
difference between battery temperature and ambient.



> storm connors <[email protected]>wrote:
> 
> > The word I got is that they can reduce the charge for high temp to
> > avoid overcharging. Apparently the max voltage is set by the
> ...


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## EVDL List (Jul 27, 2007)

Dave,
That is why the better chargers and BMS'es have
external temperature sensors that are embedded
in the pack to measure actual battery temp.

Even the cheap Solar Chargers that I have seen
have a temp sensor on the PCB and the instruction
that if you do not place the charger close to
the battery then you should remove the sensor
from the PCB, add wiring and make sure it is 
measuring the temp near the battery.

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 VoIP: +31 20 3987567 FWD# 25925
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 dave cover
Sent: Thursday, January 29, 2009 6:37 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Charger Temperature Compensation

I'd be concerned that they are monitoring "ambient" temperature and not
battery temperature. I'm just guessing, but I'd bet most people don't
have
their charger packed in with the batteries and that there will be a
difference between battery temperature and ambient.

On Wed, Jan 28, 2009 at 9:30 PM, storm connors


> <[email protected]>wrote:
> 
> > The word I got is that they can reduce the charge for high temp to
> > avoid overcharging. Apparently the max voltage is set by the
> ...


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## EVDL List (Jul 27, 2007)

Temp sensor should be mounted to the battery post. This gets a better temp
reading that is more likely to be conducted by the metal from within the
battery. You will find that most charger manuals will recommend it be
installed this way.

Mark Grasser
Eliot, ME


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of dave cover
Sent: Thursday, January 29, 2009 8:07 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Charger Temperature Compensation

I'd be concerned that they are monitoring "ambient" temperature and not
battery temperature. I'm just guessing, but I'd bet most people don't have
their charger packed in with the batteries and that there will be a
difference between battery temperature and ambient.

On Wed, Jan 28, 2009 at 9:30 PM, storm connors


> <[email protected]>wrote:
> 
> > The word I got is that they can reduce the charge for high temp to
> > avoid overcharging. Apparently the max voltage is set by the
> ...


----------



## EVDL List (Jul 27, 2007)

Which chargers are you referring to? I think the Zivan has a remote probe
option but folks here seem to like the PFC and I don't see any temperature
compensation at all. It would seem ambient would be better than nothing
even if it didn't match the battery.

Steve



> Cor van de Water <[email protected]> wrote:
> 
> > Dave,
> > That is why the better chargers and BMS'es have
> ...


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## EVDL List (Jul 27, 2007)

> On 29 Jan 2009 at 8:07, dave cover wrote:
> 
> > I'd be concerned that they are monitoring "ambient" temperature and not
> > battery temperature.
> ...


----------



## EVDL List (Jul 27, 2007)

Based on this thread, I sent QuickCharge the following note:

I have two of your chargers that have the ambient temperature compensation.
I have a large insulated battery back so I'd like to take the QuickCharge
battery case apart so I can extend the sensor to a location in the middle of
my pack. I realize this will void my warranty and I am willing to accept
that risk. Can you provide any hints on how I need to go about doing that?
Specifically, where is the sensor located in the charger and will adding
some length to the wires cause it to be inaccurate?

The response was quick but a little surprising:

"...the sensor is heatshrinked on the AC cord. That's not necessary anyway,
the batteries will not get hot during charging, and in any case you don't
want to cut down on the final finish voltage."

While the QuickCharge certainly doesn't have the flexibility of the PFC or
the Brusa, they can be programmed to a few different profiles. As I look at
programmable profiles, they seem to pretty closely match what Trojan has in
their manual for a charging profiles so does it really hurt battery life
that much? Enough to suggest that folks should spend 4-5 times as much for
a Brusa charger that has remote temperature compensation and programmable
profiles? I am a newbie on this stuff so feel free to critique since my
logic on buying the QuickCharge is probably similar to others like the op.

One thing that I don't quite understand is the Lee Hart's info on this list
says to charge to 2.4V/cell and hold. The Trojan curve drops the current
down but still allows voltage to float up to "2.45-2.7V." It seems that the
QuickCharge more closely matches the Trojan curve by allowing the voltage to
go up to 2.55 volts.

>From the manual for the QuickCharge:

F1- Float mode, charges batteries to 2.3 volts per cell before dropping into
a continuous
low float mode of 2.26 volts per cell. Ideal for starting or gel batteries.
F2- Gas and shut off mode, charges batteries to 2.3 volts per cell where a
timed gas cycle
is initiated. The voltage is allowed to climb to a maximum of 2.55 volts per
cell
before shut off. If left connected to batteries, the charger will recycle if
the voltage
drops below 2.01 VPC. Ideal for deep cycle wet batteries. (In this mode the
type
of gassing cycle, and the recycle time are programmable)
F3- Gas and float mode, charges batteries to 2.3 volts per cell where a
timed gas cycle is
initiated. The voltage is allowed to climb to a maximum of 2.55 volts per
cell before
dropping into a low float mode of 2.26 volts per cell. Ideal for wet deep
cycle
batteries where a continuous maintenance charge is desirable. (In this mode
the type
of gassing cycle is programmable)
F4- Gas and float mode, charges batteries to 2.3 volts per cell where a
timed gas cycle is
initiated. The voltage is allowed to climb to a maximum of 2.40 volts per
cell before
dropping into a low float mode of 2.26 volts per cell. Ideal for AGM
batteries .
(In this mode the type of gassing cycle is programmable)

Gassing cycle. Can be set to a three hour fixed cycle or proportional to the
cycle itself. The
proportioned cycle is based on the time it takes the batteries to reach 2.3
volts per cell known as
the gassing threshold. For example, if it takes four hours to reach the
threshold, the gassing cycle
will be two hours or 50% of that time.

The one area that does seem to fall short of more expensive chargers is
their equalization instructions:

EQUALIZATION:
When using multiple batteries in series, cells become uneven during charge
and discharge
cycles. At least once a month perform two charge cycles back to back, this
will bring up cells
that are lagging behind full charged cells and is important to overall
battery performance.





> Cor van de Water <[email protected]> wrote:
> 
> > Dave,
> > That is why the better chargers and BMS'es have
> ...


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## EVDL List (Jul 27, 2007)

> Steve Skarda wrote:
> 
> > "...the sensor is heatshrinked on the AC cord. That's not
> > necessary anyway, the batteries will not get hot during
> ...


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## EVDL List (Jul 27, 2007)

> On 29 Jan 2009 at 21:21, Roger Stockton wrote:
> 
> > 2.55V/cell is nowhere near high enough to charge your floodeds fully.
> 
> ...


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## EVDL List (Jul 27, 2007)

I appreciate your input. It really does help new folks like myself learn
some more.



> Roger Stockton <[email protected]>wrote:
> 
> > Steve Skarda wrote:
> >
> ...


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## EVDL List (Jul 27, 2007)

> Gee, I was going to say I thought it was a bit high for CV charging 
> of lead batteries at 20 deg C. I know US Battery recommends an even 
> higher voltage, 2.583vpc, but I always thought that seemed excessive 
> too. What am I missing here?

Did he mean 20 deg F?

Think more
Talk less
Become wise

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## EVDL List (Jul 27, 2007)

> Steve Skarda wrote:
> > I sent QuickCharge the following note:
> >
> > I have two of your chargers that have the ambient temperature
> ...


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## EVDL List (Jul 27, 2007)

> On 30 Jan 2009 at 9:09, Joe wrote:
> 
> > The first phase is a bulk charge where current is dumped in until voltage
> > reads 2.3 vpc. Amps ranged from around 30 amps when it first started
> ...


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## EVDL List (Jul 27, 2007)

The temp compensation is only to reduce the voltage when it is hot.
There is no provision to increase the voltage when it is cold. The
max/end voltage is determined by the transformer.



> Steve Skarda <[email protected]> wrote:
> > Based on this thread, I sent QuickCharge the following note:
> >
> > I have two of your chargers that have the ambient temperature compensation.
> ...


----------



## EVDL List (Jul 27, 2007)

>
> This strikes me as a rather odd profile.


I agree, but i think it achieves similar results in a roundabout way. It is
a less expensive charger, so...


> A more typical IU or IUI profile
> would look something like :


> Stage 1 : constant current until around 2.4 to 2.5 volts per cell


Here, I think the charger applies the output of the transformer without any
current regulation until the voltage reaches 2.3 vpc. I suspect this
explains the higher initial current that reduces as the bulk charge
continues. I think the main downside here is that the power draw from the
wall isn't maximized throughout the bulk charge cycle.


>
>
> Stage 2 : constant voltage at that voltage until the current falls to some
> small value (2-4 amps; about 2% of the battery's AH capacity expressed in
> amps)


Here, they give you 3 options - stop and go right to float, continue to 2.4
vpc and hold, or continue to 2.55 vpc and hold. As for holding the voltage,
hey give you the option of 3 hours for this whole stage or a time equal to
half the time it took to bulk charge.

Some observations here:

At 2.4 vpc, I noticed the current fall to about 2 amps and stay there.
At 2.55 vpc, the current fell to about 5 amps and stayed there.
The time from when this stage began to when the current fell to 2 amps (for
the one time that I recorded this cycle) was about half of the time it took
to 'bulk charge'.

I think this roughly accomplishes the "constant voltage at that voltage
until the current falls to some small value" stage you describe. I don't
think it is the best way... Is the time from 2.3vpc to a lot current of
2amps always half the time it takes to bulk charge? I vaguely remember
someone commenting that the time for absorbtion is proportional to the time
for bulk charge, but feedback control would be better than passive control.


>
> Stage 3 :
> (a) shutoff
>
> (b) float or
>
> (c) equalization, typically 1-3 hours at low constant current
>

Here, the charger will float or shutoff. Float charge has been the main
topic of this thread.


>
> I don't get the idea of raising the voltage for the CV finish.
>
> Nor do I understand why a CV phase would be timed (that was what you meant,
> right?). The point of CV is that the battery accepts as much charge as it
> wants; the charging current naturally falls as it fills up.



Yeah, I didn't explain it too well. Hopefully this explains what the
charger is actually doing. I think it indirectly accomplishes something
similar to the stages you describe. It'll roughly do the CV phase then
switch to float (the proportionally timed second phase) or it can continue
charging at that low final current for an equalization charge of an hour or
two then switch to float (the 3-hour second phase ).


Joe
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## EVDL List (Jul 27, 2007)

My 144v pack bulk charged until voltage=187.2v The 80% indicator came
on and it was charging at 6.8A. The amperage fell quickly while the
voltage held steady at 187.2. In 5 minutes amps dropped to 2. In
another 5 min amperage dropped to 1. 22 minutes later the amperage was
at .5 and it continued to fall until the charger indicated full
charge. I can't believe that charging at less than 1 amp has much
effect on a 170AH pack. This was using the recommended F2 charging
cycle.



> Joe <[email protected]> wrote:
> >>
> >> This strikes me as a rather odd profile.
> >
> ...


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## EVDL List (Jul 27, 2007)

> Steve Skarda wrote:
> 
> > > The cord may well warm more than the batteries during
> > > charge,
> ...


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## EVDL List (Jul 27, 2007)

I had written:

> Trojan wants you to bring their battery to 2.40-2.45V/cell at
> 80F/26.7C. You must increase that voltage by 0.005V/cell for
> each deg C that the battery temperature exceeds 26.7C and
> decrease by the same amount for each degree C below 26.7C.

NOTE: I've described this backwards! The voltage *decreases* above 26.7C/80F and *increases* below.

The correct explanation is:

Trojan wants you to bring their battery to 2.40-2.45V/cell at 80F/26.7C. You must DECREASE that voltage by 0.005V/cell for each deg C that the battery temperature exceeds 26.7C and INCREASE it by the same amount for each degree C below 26.7C.

The example was correct:

> For instance, 2.43Vpc @ 26.7C rises to 2.43 + 26.7*(0.005) =
> 2.5635V/cell @ 0C/32F.

Sorry about that,

Roger.

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## EVDL List (Jul 27, 2007)

> EVDL Administrator wrote:
> 
> > On 29 Jan 2009 at 21:21, Roger Stockton wrote:
> >
> ...


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## EVDL List (Jul 27, 2007)

> > On 30 Jan 2009 at 9:09, Joe wrote:
> >
> >> The first phase is a bulk charge where current is dumped in until
> >> voltage
> ...


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