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Discussion Starter #1
Dear List,

I'm in the market for a self contained cell cycler that I can use on
my TS cells (LFP160's). I'd rather not pay too much - assuming you
can buy one off the shelf - and so wondered if anyone has come across
a simple open source set up? I imagined something like a 600W PC PSU,
a big relay, a large possibly fan cooled load resistor and 2 line LCD
display all controlled by an arduino or pic-based controller.

In terms of spec, I suppose something like 10A in and out would do. I
know this would take a couple of days per cell but I'm not in a hurry
and really I'd only want o use it very rarely and even then only on
suspect cells. Of course quicker is better but I don't want to have
to mess around too much with massive cooling needs if the power in and
out is too high.

Regards, Martin Winlow
Herts, UK
http://www.evalbum.com/2092
www.winlow.co.uk



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Discussion Starter #2
I recently purchased a MRC Superbrain 989 charger off ebay for $75. It is still in transit, so I can't speak to how well it works yet, but it is supposed to do exactly what you are looking for. Up to 30 volt 10 amp charging as well as automated discharge testing up to 10 amps with adjustable cutoff voltage.

http://www.modelrec.com/search/product-view.asp?ID=6863

damon

> From: [email protected]
> To: [email protected]
> Date: Thu, 11 Nov 2010 16:08:21 +0000
> Subject: [EVDL] Cell Cycler - Open Source?
>
> Dear List,
>
> I'm in the market for a self contained cell cycler that I can use on
> my TS cells (LFP160's). I'd rather not pay too much - assuming you
> can buy one off the shelf - and so wondered if anyone has come across
> a simple open source set up? I imagined something like a 600W PC PSU,
> a big relay, a large possibly fan cooled load resistor and 2 line LCD
> display all controlled by an arduino or pic-based controller.
>
> In terms of spec, I suppose something like 10A in and out would do. I
> know this would take a couple of days per cell but I'm not in a hurry
> and really I'd only want o use it very rarely and even then only on
> suspect cells. Of course quicker is better but I don't want to have
> to mess around too much with massive cooling needs if the power in and
> out is too high.
>
> Regards, Martin Winlow
> Herts, UK
> http://www.evalbum.com/2092
> www.winlow.co.uk
>
>
>
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Discussion Starter #3
Thanks chaps - Sounds ideal. I have my eye on one now.

Regards, Martin Winlow
Herts, UK
http://www.evalbum.com/2092
www.winlow.co.uk


Martin WINLOW wrote:

> Dear List,
>
> I'm in the market for a self contained cell cycler that I can use on
> my TS cells (LFP160's). I'd rather not pay too much - assuming you
> can buy one off the shelf - and so wondered if anyone has come across
> a simple open source set up? I imagined something like a 600W PC PSU,
> a big relay, a large possibly fan cooled load resistor and 2 line LCD
> display all controlled by an arduino or pic-based controller.
>
> In terms of spec, I suppose something like 10A in and out would do. I
> know this would take a couple of days per cell but I'm not in a hurry
> and really I'd only want o use it very rarely and even then only on
> suspect cells. Of course quicker is better but I don't want to have
> to mess around too much with massive cooling needs if the power in and
> out is too high.
>
> Regards, Martin Winlow
> Herts, UK
> http://www.evalbum.com/2092
> www.winlow.co.uk

_______________________________________________
| REPLYING: address your message to [email protected] only.
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Discussion Starter #4
I've been thinking about this problem for a while. I am willing to "donate"
my scheme to the community for development.

The first concern I have had is the 100% energy waste of the approaches I've
seen. It's been all about having a good, safe load bank. Let's avoid that!
Here's how:

The setup requires 4 identical batteries.
Two double-pole, double-throw relays connect them pair wise, one set in
series and the other in parallel.
Other relays would connect the series pair to the input of a PWM controller
and the controller output to the parallel pair maybe through a choke.
In operation the series pair are discharged at the chosen rate while the
parallel pair are charged at 1/2 that rate.
After discharge to the selected DOD, the connections are reversed.
One issue is equalizing the voltages on the discharged pair before
connecting them in parallel. Maybe making the parallel connection through a
light bulb initially, then shorting.
There also needs to be a provision for topping off the charged pair before
series connecting them.

Yours,
Gerhard

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Martin WINLOW
Sent: Thursday, November 11, 2010 11:08 AM
To: EVDL Post Message
Subject: [EVDL] Cell Cycler - Open Source?

Dear List,

I'm in the market for a self contained cell cycler that I can use on
my TS cells (LFP160's). I'd rather not pay too much - assuming you
can buy one off the shelf - and so wondered if anyone has come across
a simple open source set up? I imagined something like a 600W PC PSU,
a big relay, a large possibly fan cooled load resistor and 2 line LCD
display all controlled by an arduino or pic-based controller.

In terms of spec, I suppose something like 10A in and out would do. I
know this would take a couple of days per cell but I'm not in a hurry
and really I'd only want o use it very rarely and even then only on
suspect cells. Of course quicker is better but I don't want to have
to mess around too much with massive cooling needs if the power in and
out is too high.

Regards, Martin Winlow
Herts, UK
http://www.evalbum.com/2092
www.winlow.co.uk



_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
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| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev


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Discussion Starter #5
Gerhard Randers-Pehrson wrote:
> I've been thinking about this problem for a while. I am willing to "donate"
> my scheme to the community for development...

Hello Gerhard,

Actually, your scheme is one that was used in many of the earliest EVs.
They used switches or contactors to reconnect their batteries in
series/parallel combinations. For example, a 72v pack might consist or
six 12v batteries. They can be connected

- all in parallel for 12v
- as three parallel strings of two in series for 24v
- as two parallel strings of three in series for 36v
- all in series for 72v

It works quite well. It provides the speed control, and balances the
charge between batteries, all at essentially 100% efficiency. The main
drawback are the voltage steps. If they get too large, throttle
operation gets too "jerky".

In parallel, the batteries have the same voltage, and so self-balance to
the same state of charge. For a lead-acid battery, voltage is
proportional to state of charge, so the more-charged battery charges the
lower-charged one.

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

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Discussion Starter #6
Oops, error..
The charging and discharging rates are the same, because of the
voltage*current transforming by the buck converter.
Gerhard

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Gerhard Randers-Pehrson
Sent: Friday, November 12, 2010 11:54 AM
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] Cell Cycler - Open Source?

I've been thinking about this problem for a while. I am willing to "donate"
my scheme to the community for development.

The first concern I have had is the 100% energy waste of the approaches I've
seen. It's been all about having a good, safe load bank. Let's avoid that!
Here's how:

The setup requires 4 identical batteries.
Two double-pole, double-throw relays connect them pair wise, one set in
series and the other in parallel.
Other relays would connect the series pair to the input of a PWM controller
and the controller output to the parallel pair maybe through a choke.
In operation the series pair are discharged at the chosen rate while the
parallel pair are charged at 1/2 that rate.
After discharge to the selected DOD, the connections are reversed.
One issue is equalizing the voltages on the discharged pair before
connecting them in parallel. Maybe making the parallel connection through a
light bulb initially, then shorting.
There also needs to be a provision for topping off the charged pair before
series connecting them.

Yours,
Gerhard

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Martin WINLOW
Sent: Thursday, November 11, 2010 11:08 AM
To: EVDL Post Message
Subject: [EVDL] Cell Cycler - Open Source?

Dear List,

I'm in the market for a self contained cell cycler that I can use on
my TS cells (LFP160's). I'd rather not pay too much - assuming you
can buy one off the shelf - and so wondered if anyone has come across
a simple open source set up? I imagined something like a 600W PC PSU,
a big relay, a large possibly fan cooled load resistor and 2 line LCD
display all controlled by an arduino or pic-based controller.

In terms of spec, I suppose something like 10A in and out would do. I
know this would take a couple of days per cell but I'm not in a hurry
and really I'd only want o use it very rarely and even then only on
suspect cells. Of course quicker is better but I don't want to have
to mess around too much with massive cooling needs if the power in and
out is too high.

Regards, Martin Winlow
Herts, UK
http://www.evalbum.com/2092
www.winlow.co.uk



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| Multiple-address or CCed messages may be rejected.
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Discussion Starter #7
Hi Gerhard,

I think your scheme would involve disconnecting the cells from the
pack, yes? If so, this would mean a lot of work making and braking
connections which would normally be best left undisturbed. It is an
interesting system though!

Regards, Martin Winlow
Herts, UK
http://www.evalbum.com/2092
www.winlow.co.uk


Gerhard Randers-Pehrson wrote:

> I've been thinking about this problem for a while. I am willing to
> "donate"
> my scheme to the community for development.
>
> The first concern I have had is the 100% energy waste of the
> approaches I've
> seen. It's been all about having a good, safe load bank. Let's avoid
> that!
> Here's how:
>
> The setup requires 4 identical batteries.
> Two double-pole, double-throw relays connect them pair wise, one set
> in
> series and the other in parallel.
> Other relays would connect the series pair to the input of a PWM
> controller
> and the controller output to the parallel pair maybe through a choke.
> In operation the series pair are discharged at the chosen rate while
> the
> parallel pair are charged at 1/2 that rate.
> After discharge to the selected DOD, the connections are reversed.
> One issue is equalizing the voltages on the discharged pair before
> connecting them in parallel. Maybe making the parallel connection
> through a
> light bulb initially, then shorting.
> There also needs to be a provision for topping off the charged pair
> before
> series connecting them.
>
> Yours,
> Gerhard
>

> -----Original Message-----
> Of Martin WINLOW
>
> Dear List,
>
> I'm in the market for a self contained cell cycler that I can use on
> my TS cells (LFP160's). I'd rather not pay too much - assuming you
> can buy one off the shelf - and so wondered if anyone has come across
> a simple open source set up? I imagined something like a 600W PC PSU,
> a big relay, a large possibly fan cooled load resistor and 2 line LCD
> display all controlled by an arduino or pic-based controller.
>
> In terms of spec, I suppose something like 10A in and out would do. I
> know this would take a couple of days per cell but I'm not in a hurry
> and really I'd only want o use it very rarely and even then only on
> suspect cells. Of course quicker is better but I don't want to have
> to mess around too much with massive cooling needs if the power in and
> out is too high.
>
> Regards, Martin Winlow
> Herts, UK
> http://www.evalbum.com/2092
> www.winlow.co.uk
>




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| Multiple-address or CCed messages may be rejected.
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Discussion Starter #8
A bit more googling threw up the FMA Inc PowerLab 8 (
http://www.store.revolectrix.com/Products/Cellpro-PowerLab/Cellpro-PowerLab-8
manual here http://www.heliguy.com/revolectrix/Manuals/Powerlab8Manual.pdf
).

It has a 1000W charge/discharge capability, will do up to 360Ah. It has a
regen facility to reduce waste energy - ie if you use a large lead-acid
battery as the power supply, during discharge of the test cell, the PL8
takes energy out of the test cell and puts it back into the power supply
battery.

It has a built in USB interface which allows graphing of data but also
allows the user to control the PL8 from within the free software.

All in all, it appears nearly ideal.

The US$200 odd price means it isn't worth 'rolling my own'.

MW
--
View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Cell-Cycler-Open-Source-tp3038103p3080111.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.

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Discussion Starter #9
I assume you are not using that on a single cell? This is what I want
to do - test a single cell once in a blue moon to chart its health
over its lifetime. MW

gary wrote:

> After the last discussion on battery capacity testing here, I bought a
> 1500W inverter for $100 on Amazon. I had a 1500W heater and a KW
> meter
> (not even needed because the inverter has an LED display for
> input/output voltage and watts). I wish it had an ah counter but
> overall it is a fairly cheap way to do a capacity test, and you can
> always use the inverter if you have an EV anyway. I just set it for
> 100
> A draw and measure the time. It has a low input voltage buzzer and
> then
> it shuts down at 10.5 volts.
>
> Gary Krysztopik
> ZWheelz, LLC - www.ZWheelz.com
> Alamo City Electric Auto Association - www.aceaa.org
> blog - http://voices.mysanantonio.com/drive_electric_san_antonio/
> San Antonio, TX
>
>
> On 12/9/2010 12:05 PM, Lee Hart wrote:
>> On 12/9/2010 7:09 AM, martinwinlow wrote:
>>> A bit more googling threw up the FMA Inc PowerLab 8 (
>>> http://www.store.revolectrix.com/Products/Cellpro-PowerLab/Cellpro-PowerLab-8
>>> manual here http://www.heliguy.com/revolectrix/Manuals/Powerlab8Manual.pdf
>>> ).
>> It sounds great! But the price is so low that it makes me worry.
>>
>> They are long on advertising hype, and short on actual specs. Flashy
>> package, and lead wires that don't look capable of handling the
>> currents
>> they claim.
>>
>> I'm not going to go first! If anyone does, please let us know how it
>> works out.
>>
>

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