Maxwell Supercap 16v modules could protect my expensive lithium batteries.

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Maxwell Supercap 16v modules could protect my expensive lithium batteries.

Electric Vehicle Discussion List mailing list
I am looking to buffer my 24 volt Valence 40 ah pack. It puts out 30 amps continuous. 90 in burst mode for 90 seconds. The eGo scooter it is in can draw well over 100 amps accelerating or climbing a hill. Maxwell makes small and large 16v modules. Two modules in series is well enough over the charger voltage not to scorch them.  I think the 300 dollars of caps would protect the pack and increase performance.  Lawrence Rhodes
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Re: Maxwell Supercap 16v modules could protect my expensive lithium batteries.

Electric Vehicle Discussion List mailing list
On 26 Feb 2019 at 21:48, Lawrence Rhodes via EV wrote:

> I think the 300 dollars of caps would protect the pack and increase
> performance.

Probably not all by themselves.  The problem with capacitors is that, unlike
batteries, their voltage falls rapidly as they discharge.  

What you're trying to do is exactly what Solectria did experimentally in
2000, but what they had that you haven't mentioned is the wide-range input
DC:DC boost converter that kept the caps' voltage up where it needed to be
as the caps discharged.

http://www.evdl.org/docs/supercap_leveler.pdf

The EEs here can correct me if I'm wrong, but I'm afraid that a DC:DC with
that wide an input voltage range is going to cost you a bundle.  And you
will probably find, as Solectria did, that its efficiency isn't all that
great.

But you might scout around where the small Chinese industrial and hobbyist
electronics manufacturers hang out (Ebay, Aliexpress, maybe Banggood) and
see if you can find something usable, reliable and/or affordable (pick two).
I've seen a few constant voltage regulator boost and buck/boost modules
offered.  Maybe you can find one that would work for you, at least until its
magic white smoke escapes. :-)

David Roden - Akron, Ohio, USA
EVDL Administrator

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Re: Maxwell Supercap 16v modules could protect my expensive lithium batteries.

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I have 22x2600f super caps in series in my ev. They are simply
paralleled with the battery pack and perform two functions: the first is
that they take all the heavy grunt in terms of initail power start up
much means that the batteries don't see the big spikes and are treated a
lot better therefore prolonging their life. The second point is that the
caps can take far higher charge currents compared to the battery so when
regen is active, higher regen currents can be extracted. The charge goes
into the caps first which then feed it out to the batteries.

Anything else and the capacitors will need a dc-dc converter(s) that is
bidirectional to allow the rising and falling voltage to be allowed for.
These are not cheap. This is why I opted for the simple parallel them
up. Take care with them - they can source and sink thousands of A albeit
for a second but it is enough to weld wire/contacts. When connecting
them to batteries, the caps need to be charged up with a constant
current supply until the voltages match. Otherwise it is arc welding time!


On 26/02/2019 22:56, EVDL Administrator via EV wrote:

> On 26 Feb 2019 at 21:48, Lawrence Rhodes via EV wrote:
>
>> I think the 300 dollars of caps would protect the pack and increase
>> performance.
> Probably not all by themselves.  The problem with capacitors is that, unlike
> batteries, their voltage falls rapidly as they discharge.
>
> What you're trying to do is exactly what Solectria did experimentally in
> 2000, but what they had that you haven't mentioned is the wide-range input
> DC:DC boost converter that kept the caps' voltage up where it needed to be
> as the caps discharged.
>
> http://www.evdl.org/docs/supercap_leveler.pdf
>
> The EEs here can correct me if I'm wrong, but I'm afraid that a DC:DC with
> that wide an input voltage range is going to cost you a bundle.  And you
> will probably find, as Solectria did, that its efficiency isn't all that
> great.
>
> But you might scout around where the small Chinese industrial and hobbyist
> electronics manufacturers hang out (Ebay, Aliexpress, maybe Banggood) and
> see if you can find something usable, reliable and/or affordable (pick two).
> I've seen a few constant voltage regulator boost and buck/boost modules
> offered.  Maybe you can find one that would work for you, at least until its
> magic white smoke escapes. :-)
>
> David Roden - Akron, Ohio, USA
> EVDL Administrator
>
> = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
> EVDL Information: http://www.evdl.org/help/
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> reach me.  To send a private message, please obtain my
> email address from the webpage http://www.evdl.org/help/ .
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>
>
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Re: Maxwell Supercap 16v modules could protect my expensive lithium batteries.

Electric Vehicle Discussion List mailing list
 Thank you Steve,
This is what I am talking about.  A simple system. Is it possible you can provide a diagram of your setup?  I was going to put two 16v modules in series to feed and take from my 24volt system which would be connected in parallel.    I think the Maxwell modules might be better as they have built in hardware to support some functions.I would use a sacrificial tether to hook them up.  Thanks for the warning.  Lawrence Rhodes

    On Wednesday, February 27, 2019, 2:18:58 AM PST, Steve Heath <[hidden email]> wrote:  
 
 I have 22x2600f super caps in series in my ev. They are simply
paralleled with the battery pack and perform two functions: the first is
that they take all the heavy grunt in terms of initail power start up
much means that the batteries don't see the big spikes and are treated a
lot better therefore prolonging their life. The second point is that the
caps can take far higher charge currents compared to the battery so when
regen is active, higher regen currents can be extracted. The charge goes
into the caps first which then feed it out to the batteries.

Anything else and the capacitors will need a dc-dc converter(s) that is
bidirectional to allow the rising and falling voltage to be allowed for.
These are not cheap. This is why I opted for the simple parallel them
up. Take care with them - they can source and sink thousands of A albeit
for a second but it is enough to weld wire/contacts. When connecting
them to batteries, the caps need to be charged up with a constant
current supply until the voltages match. Otherwise it is arc welding time!


On 26/02/2019 22:56, EVDL Administrator via EV wrote:

> On 26 Feb 2019 at 21:48, Lawrence Rhodes via EV wrote:
>
>> I think the 300 dollars of caps would protect the pack and increase
>> performance.
> Probably not all by themselves.  The problem with capacitors is that, unlike
> batteries, their voltage falls rapidly as they discharge.
>
> What you're trying to do is exactly what Solectria did experimentally in
> 2000, but what they had that you haven't mentioned is the wide-range input
> DC:DC boost converter that kept the caps' voltage up where it needed to be
> as the caps discharged.
>
> http://www.evdl.org/docs/supercap_leveler.pdf
>
> The EEs here can correct me if I'm wrong, but I'm afraid that a DC:DC with
> that wide an input voltage range is going to cost you a bundle.  And you
> will probably find, as Solectria did, that its efficiency isn't all that
> great.
>
> But you might scout around where the small Chinese industrial and hobbyist
> electronics manufacturers hang out (Ebay, Aliexpress, maybe Banggood) and
> see if you can find something usable, reliable and/or affordable (pick two).
> I've seen a few constant voltage regulator boost and buck/boost modules
> offered.  Maybe you can find one that would work for you, at least until its
> magic white smoke escapes. :-)
>
> David Roden - Akron, Ohio, USA
> EVDL Administrator
>
> = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
> EVDL Information: http://www.evdl.org/help/
> = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
> Note: mail sent to "evpost" and "etpost" addresses will not
> reach me.  To send a private message, please obtain my
> email address from the webpage http://www.evdl.org/help/ .
> = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
>
>
> _______________________________________________
> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
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> Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
>
>
 
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Re: Maxwell Supercap 16v modules could protect my expensive lithium batteries.

Electric Vehicle Discussion List mailing list
I'm wondering how much capacity the capacitors are adding to the system,
as the voltage of the capacitors can never go below the sag voltage of
the LiIon cells under load, and can never go above the LiIon cells
voltage during regen.

I'd love to see a comparison graph of the voltage of the system battery
bank during a hard acceleration and a hard regen event both with and
without the capacitors installed to see the voltage regulation effect.

Jay

On 2/27/19 10:40 AM, Lawrence Rhodes via EV wrote:

>   Thank you Steve,
> This is what I am talking about.  A simple system. Is it possible you can provide a diagram of your setup?  I was going to put two 16v modules in series to feed and take from my 24volt system which would be connected in parallel.    I think the Maxwell modules might be better as they have built in hardware to support some functions.I would use a sacrificial tether to hook them up.  Thanks for the warning.  Lawrence Rhodes
>
>      On Wednesday, February 27, 2019, 2:18:58 AM PST, Steve Heath <[hidden email]> wrote:
>  
>   I have 22x2600f super caps in series in my ev. They are simply
> paralleled with the battery pack and perform two functions: the first is
> that they take all the heavy grunt in terms of initail power start up
> much means that the batteries don't see the big spikes and are treated a
> lot better therefore prolonging their life. The second point is that the
> caps can take far higher charge currents compared to the battery so when
> regen is active, higher regen currents can be extracted. The charge goes
> into the caps first which then feed it out to the batteries.
>
> Anything else and the capacitors will need a dc-dc converter(s) that is
> bidirectional to allow the rising and falling voltage to be allowed for.
> These are not cheap. This is why I opted for the simple parallel them
> up. Take care with them - they can source and sink thousands of A albeit
> for a second but it is enough to weld wire/contacts. When connecting
> them to batteries, the caps need to be charged up with a constant
> current supply until the voltages match. Otherwise it is arc welding time!
>
>
> On 26/02/2019 22:56, EVDL Administrator via EV wrote:
>> On 26 Feb 2019 at 21:48, Lawrence Rhodes via EV wrote:
>>
>>> I think the 300 dollars of caps would protect the pack and increase
>>> performance.
>> Probably not all by themselves.  The problem with capacitors is that, unlike
>> batteries, their voltage falls rapidly as they discharge.
>>
>> What you're trying to do is exactly what Solectria did experimentally in
>> 2000, but what they had that you haven't mentioned is the wide-range input
>> DC:DC boost converter that kept the caps' voltage up where it needed to be
>> as the caps discharged.
>>
>> http://www.evdl.org/docs/supercap_leveler.pdf
>>
>> The EEs here can correct me if I'm wrong, but I'm afraid that a DC:DC with
>> that wide an input voltage range is going to cost you a bundle.  And you
>> will probably find, as Solectria did, that its efficiency isn't all that
>> great.
>>
>> But you might scout around where the small Chinese industrial and hobbyist
>> electronics manufacturers hang out (Ebay, Aliexpress, maybe Banggood) and
>> see if you can find something usable, reliable and/or affordable (pick two).
>> I've seen a few constant voltage regulator boost and buck/boost modules
>> offered.  Maybe you can find one that would work for you, at least until its
>> magic white smoke escapes. :-)
>>
>> David Roden - Akron, Ohio, USA
>> EVDL Administrator
>>
>> = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
>> EVDL Information: http://www.evdl.org/help/
>> = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
>> Note: mail sent to "evpost" and "etpost" addresses will not
>> reach me.  To send a private message, please obtain my
>> email address from the webpage http://www.evdl.org/help/ .
>> = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
>>
>>
>> _______________________________________________
>> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
>> http://lists.evdl.org/listinfo.cgi/ev-evdl.org
>> Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
>>
>>
>    
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Re: Maxwell Supercap 16v modules could protect my expensive lithium batteries.

Electric Vehicle Discussion List mailing list
Jay Summet wrote:

> I'm wondering how much capacity the capacitors are adding to the system,
> as the voltage of the capacitors can never go below the sag voltage of
> the LiIon cells under load, and can never go above the LiIon cells
> voltage during regen.
>
> I'd love to see a comparison graph of the voltage of the system battery
> bank during a hard acceleration and a hard regen event both with and
> without the capacitors installed to see the voltage regulation effect.

Victor Tikhonov (of MetricMind) used a string of 2.7kF Maxwell supercaps (17F total) in parallel with the lithium pack in his CRX conversion, back in 2004.

Something Victor mentioned on the site for his conversion is the need to disconnect the string of caps from the battery during charge.

Unfortunately, the links in Victor's original message (quoted below) appear dead, however, his comments describing the results of his measurements are still informative.

> -----Original Message-----
> From: Victor Tikhonov [mailto:[hidden email]]
> Sent: October-07-04 4:53 PM
> To: [hidden email]
> Subject: Does the passive balancing of uptracaps stack really works?
>
> I've made a few measurements on the most easily accessible
> caps (last 10 caps in the series string) after couple of
> driving/charging cycles. Objective was to see if they are
> drifting apart far enough that the passive resistor based
> balancing cannot keep up with bringing them all back to order.
>
> Looks like whatever initial voltages are settling at, they all
> go up and down at the same rate, so at the end of the day
> while overall average SOC is different, deltas between the same
> caps are still identical. Which tells me that for my circumstances
> making active balancing would be waste of effort.
>
> Will see how well this keeps repeating in the long run.
>
> http://www.metricmind.com/misc/ultracap.gif
>
> In case you missed the link showing about 10x stiffness
> improvement using ultracaps, captured data screens are here:
>
> http://www.metricmind.com/misc/test1.gif
> Left half - with caps, right half - without.
> (did few hard regens in the middle - to separate data points)
>
> Zoomed in version:
> http://www.metricmind.com/misc/compare.gif
>
> I'm noticing a side benefit I didn't think of before:
> no matter what the SOC of the battery is, combined
> with ultracaps it feels just as stiff at the end of
> discharge as full. This is because ultracaps have fixed
> internal resistance no matter how discharged they are.
>
> When the pack getting tired, recharging caps from LiIons
> after accelerations getting slower, but by the time it is
> completed, the pack is as stiff for the next acceleration
> as the fresh one.
>
>  From here (bottom plot) you can see how efficient
> my system happen to be (motor power out / batt power in):
>
> http://www.metricmind.com/misc/eff.gif
> This is actually unrelated to the presence of the capacitors.
>
> So far I'm very pleased with outcome of my setup. LiIons
> don't get much chance to see more than 30A out of them
> during quick accelerations, the same absorbing regen.
> The caps do all the work :-)
>
> --
> Victor
> '91 ACRX - something different
>
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(metricmind.com links): Supercaps reduce li-ion pack sagging

Electric Vehicle Discussion List mailing list
jay sez >Victor Tikhonov (of MetricMind) used a string of 2.7kF Maxwell
supercaps<

Advanced electric vehicle conversion project - Battery ... - Metric Mind
www.metricmind.com/ac_honda/ultracaps.htm
The power boost ultracapacitor stack. Manufacturer: Maxwell technologies.
Cost: $4,800 (liquidation sale). Ultracaps The LiIon battery I use proved to
be a good ...

Advanced electric vehicle conversion project - Metric Mind
www.metricmind.com/ac_honda/main2.htm
... 10 LEad acid batteries will be replaced with 28 ones, later - with 96
LiIon ones (later supplemented with ultracapacitor bank) and then - with 24
NiMH ones??

FAQ | Metric Mind Corporation
www.metricmind.com/education/
... AC drives available for amateur conversions since 2003, first use of
supercapacitors, first lithium ion batteries (Honda ACRX), first
informational LED lighting, ...

High End No Compromise Electric Vehicle Conversion ... - Metric Mind
www.metricmind.com/audi/1-initial.htm
Apr 6, 2008 - I installed AC drive system, tried several battery types (Lead
Acid, Lithium Ion and Nickel Metal Hydride), ultracapacitors and few other
novel at ...

https://www.google.com/search?q=Metric+Mind+ultracapacitors




For EVLN EV-newswire posts use:
 http://evdl.org/archive/


{brucedp.neocities.org}

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Re: (metricmind.com links): Supercaps reduce li-ion pack sagging

Electric Vehicle Discussion List mailing list
His use of Supercaps was a bandaid: due to the excessive internal resistance of the LiIon batteries that he found, he had to make up a solution to give him the ability for a short power burst (to merge on freeway for example).
Supercaps happened to be on sale, so it worked out for him, but they do not add range, just a temporary boost.
If you add a parallel pack of batteries, you add both range and double the current (or half the voltage sag) of your pack, so that is typically preferred.
I have a similar situation: well-used Nissan Leaf 1st gen batteries that tend to sag quite a bit due to increasing internal resistance, but with 2 packs in parallel, each only sees half the current so the sag is reduced and my range more than doubled.
Cor.

Sent from Mail for Windows 10

From: brucedp5 via EV
Sent: Wednesday, February 27, 2019 8:55 PM
To: [hidden email]
Cc: brucedp5
Subject: [EVDL] (metricmind.com links): Supercaps reduce li-ion pack sagging

jay sez >Victor Tikhonov (of MetricMind) used a string of 2.7kF Maxwell
supercaps<

Advanced electric vehicle conversion project - Battery ... - Metric Mind
www.metricmind.com/ac_honda/ultracaps.htm
The power boost ultracapacitor stack. Manufacturer: Maxwell technologies.
Cost: $4,800 (liquidation sale). Ultracaps The LiIon battery I use proved to
be a good ...

Advanced electric vehicle conversion project - Metric Mind
www.metricmind.com/ac_honda/main2.htm
... 10 LEad acid batteries will be replaced with 28 ones, later - with 96
LiIon ones (later supplemented with ultracapacitor bank) and then - with 24
NiMH ones??

FAQ | Metric Mind Corporation
www.metricmind.com/education/
... AC drives available for amateur conversions since 2003, first use of
supercapacitors, first lithium ion batteries (Honda ACRX), first
informational LED lighting, ...

High End No Compromise Electric Vehicle Conversion ... - Metric Mind
www.metricmind.com/audi/1-initial.htm
Apr 6, 2008 - I installed AC drive system, tried several battery types (Lead
Acid, Lithium Ion and Nickel Metal Hydride), ultracapacitors and few other
novel at ...

https://www.google.com/search?q=Metric+Mind+ultracapacitors




For EVLN EV-newswire posts use:
 http://evdl.org/archive/


{brucedp.neocities.org}

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Re: Maxwell Supercap 16v modules could protect my expensive lithium batteries.

Electric Vehicle Discussion List mailing list
In reply to this post by Electric Vehicle Discussion List mailing list
You can grab old files from Victor's old website via the Wayback Machine (
archive.org).

https://web.archive.org/web/20051031031417/http://www.metricmind.com/misc/ultracap.gif
https://web.archive.org/web/20051031031314/http://www.metricmind.com/misc/test1.gif
https://web.archive.org/web/20051031031004/http://www.metricmind.com/misc/compare.gif

Phil H.

On Wed, Feb 27, 2019 at 10:14 AM Roger Stockton via EV <[hidden email]>
wrote:

> Jay Summet wrote:
>
> > I'm wondering how much capacity the capacitors are adding to the system,
> > as the voltage of the capacitors can never go below the sag voltage of
> > the LiIon cells under load, and can never go above the LiIon cells
> > voltage during regen.
> >
> > I'd love to see a comparison graph of the voltage of the system battery
> > bank during a hard acceleration and a hard regen event both with and
> > without the capacitors installed to see the voltage regulation effect.
>
> Victor Tikhonov (of MetricMind) used a string of 2.7kF Maxwell supercaps
> (17F total) in parallel with the lithium pack in his CRX conversion, back
> in 2004.
>
> Something Victor mentioned on the site for his conversion is the need to
> disconnect the string of caps from the battery during charge.
>
> Unfortunately, the links in Victor's original message (quoted below)
> appear dead, however, his comments describing the results of his
> measurements are still informative.
>
> > -----Original Message-----
> > From: Victor Tikhonov [mailto:[hidden email]]
> > Sent: October-07-04 4:53 PM
> > To: [hidden email]
> > Subject: Does the passive balancing of uptracaps stack really works?
> >
> > I've made a few measurements on the most easily accessible
> > caps (last 10 caps in the series string) after couple of
> > driving/charging cycles. Objective was to see if they are
> > drifting apart far enough that the passive resistor based
> > balancing cannot keep up with bringing them all back to order.
> >
> > Looks like whatever initial voltages are settling at, they all
> > go up and down at the same rate, so at the end of the day
> > while overall average SOC is different, deltas between the same
> > caps are still identical. Which tells me that for my circumstances
> > making active balancing would be waste of effort.
> >
> > Will see how well this keeps repeating in the long run.
> >
> > http://www.metricmind.com/misc/ultracap.gif
> >
> > In case you missed the link showing about 10x stiffness
> > improvement using ultracaps, captured data screens are here:
> >
> > http://www.metricmind.com/misc/test1.gif
> > Left half - with caps, right half - without.
> > (did few hard regens in the middle - to separate data points)
> >
> > Zoomed in version:
> > http://www.metricmind.com/misc/compare.gif
> >
> > I'm noticing a side benefit I didn't think of before:
> > no matter what the SOC of the battery is, combined
> > with ultracaps it feels just as stiff at the end of
> > discharge as full. This is because ultracaps have fixed
> > internal resistance no matter how discharged they are.
> >
> > When the pack getting tired, recharging caps from LiIons
> > after accelerations getting slower, but by the time it is
> > completed, the pack is as stiff for the next acceleration
> > as the fresh one.
> >
> >  From here (bottom plot) you can see how efficient
> > my system happen to be (motor power out / batt power in):
> >
> > http://www.metricmind.com/misc/eff.gif
> > This is actually unrelated to the presence of the capacitors.
> >
> > So far I'm very pleased with outcome of my setup. LiIons
> > don't get much chance to see more than 30A out of them
> > during quick accelerations, the same absorbing regen.
> > The caps do all the work :-)
> >
> > --
> > Victor
> > '91 ACRX - something different
> >
> _______________________________________________
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Re: (metricmind.com links): Supercaps reduce li-ion pack sagging

Electric Vehicle Discussion List mailing list
In reply to this post by Electric Vehicle Discussion List mailing list
Adding supercapacitors in parallel with the approproate balancing
circuits (Aliexpress is your friend) is more about making the battery
life easier and for recoving more of the available regen current. Proper
balancing circuits and not simple resistors is a must in my experience
as you need to prevent the voltage across the capacitor from exceeding
its spec = typically around 2.7 v. This is why you need a lot in series
to cope with high voltages. I have 22 in series which means that They
stack is ok upto 59.4 which gives a nice safety margin over the 54.2V
the pack can provide when fully charged.

This kinder environment does extend the range as more of the battery
capacity can be extracted. On some of the studies shown indicate an
improvement of about 15-18% on the range. Yes adding additional packs
inparallel is always a big help, but the batteries are still exposed to
the high peaks albeit at a lower level and it is these peaks that the
supercaps prevent/mitagate/remove (select as appropriate).

The energy that is available from the caps is not the complete energy
stored as the voltage will go from 4.2 to 2.8v on each lithium cell. So
on my 48v system this means from 54.2 to around 36v which is still an
appreciable amount. The leads and battery internal resistance
effectively act as resistors so when the motor wants big power, the path
of least resistance comes into play and it is the supercapacitor that
provides the main power for the peak.As the peak goes down and the
supercapacitor voltage drops, the main batteries take over and some
current is diverted to the caps to bring them up to voltage. This
happens very quickly so in most cases, it is not seen with simple
instrumentation.

When I disconnected the super caps, I did see a significant reduction in
the regen currents I could achieve:  40-50A instead of the 120-130A . I
also saw a far higher voltage drop on the battery packs after hard
acceleration. I also saw a slower voltage recovery time as well.

So they are very beneficial. Yes adding more packs will show some
similar benefits, but the issue of peak currents is not totally
addressed. Yes they are reduced because of the greater load sharing but
they are still present. In summary:  Supercaps can harvest more regen
current, provide a kinder environment for the batteries and give some
improved range. Adding more batteries places less stress on the
batteries, will harvest more regen current but nowhere near the level
that a supercapcitor will and will give significantly more range. The
environment is still not very nice as the peaks will still be there.

Which way to choose depends on the problems that are being addressed and
the relative costs of the solutions.

You pays your money and you takes your choice.


Steve

On 28/02/2019 05:55, Cor van de Water via EV wrote:

> His use of Supercaps was a bandaid: due to the excessive internal resistance of the LiIon batteries that he found, he had to make up a solution to give him the ability for a short power burst (to merge on freeway for example).
> Supercaps happened to be on sale, so it worked out for him, but they do not add range, just a temporary boost.
> If you add a parallel pack of batteries, you add both range and double the current (or half the voltage sag) of your pack, so that is typically preferred.
> I have a similar situation: well-used Nissan Leaf 1st gen batteries that tend to sag quite a bit due to increasing internal resistance, but with 2 packs in parallel, each only sees half the current so the sag is reduced and my range more than doubled.
> Cor.
>
> Sent from Mail for Windows 10
>
> From: brucedp5 via EV
> Sent: Wednesday, February 27, 2019 8:55 PM
> To: [hidden email]
> Cc: brucedp5
> Subject: [EVDL] (metricmind.com links): Supercaps reduce li-ion pack sagging
>
> jay sez >Victor Tikhonov (of MetricMind) used a string of 2.7kF Maxwell
> supercaps<
>
> Advanced electric vehicle conversion project - Battery ... - Metric Mind
> www.metricmind.com/ac_honda/ultracaps.htm
> The power boost ultracapacitor stack. Manufacturer: Maxwell technologies.
> Cost: $4,800 (liquidation sale). Ultracaps The LiIon battery I use proved to
> be a good ...
>
> Advanced electric vehicle conversion project - Metric Mind
> www.metricmind.com/ac_honda/main2.htm
> ... 10 LEad acid batteries will be replaced with 28 ones, later - with 96
> LiIon ones (later supplemented with ultracapacitor bank) and then - with 24
> NiMH ones??
>
> FAQ | Metric Mind Corporation
> www.metricmind.com/education/
> ... AC drives available for amateur conversions since 2003, first use of
> supercapacitors, first lithium ion batteries (Honda ACRX), first
> informational LED lighting, ...
>
> High End No Compromise Electric Vehicle Conversion ... - Metric Mind
> www.metricmind.com/audi/1-initial.htm
> Apr 6, 2008 - I installed AC drive system, tried several battery types (Lead
> Acid, Lithium Ion and Nickel Metal Hydride), ultracapacitors and few other
> novel at ...
>
> https://www.google.com/search?q=Metric+Mind+ultracapacitors
>
>
>
>
> For EVLN EV-newswire posts use:
>   http://evdl.org/archive/
>
>
> {brucedp.neocities.org}
>
> --
> Sent from: http://electric-vehicle-discussion-list.413529.n4.nabble.com/
> _______________________________________________
> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
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>
>
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Re: (metricmind.com links): Supercaps reduce li-ion pack sagging

Electric Vehicle Discussion List mailing list
You are better off to add more batteries in parallel than caps.

Sent from my iPhone

> On Mar 1, 2019, at 3:33 AM, Steve Heath via EV <[hidden email]> wrote:
>
> Adding supercapacitors in parallel with the approproate balancing circuits (Aliexpress is your friend) is more about making the battery life easier and for recoving more of the available regen current. Proper balancing circuits and not simple resistors is a must in my experience as you need to prevent the voltage across the capacitor from exceeding its spec = typically around 2.7 v. This is why you need a lot in series to cope with high voltages. I have 22 in series which means that They stack is ok upto 59.4 which gives a nice safety margin over the 54.2V the pack can provide when fully charged.
>
> This kinder environment does extend the range as more of the battery capacity can be extracted. On some of the studies shown indicate an improvement of about 15-18% on the range. Yes adding additional packs inparallel is always a big help, but the batteries are still exposed to the high peaks albeit at a lower level and it is these peaks that the supercaps prevent/mitagate/remove (select as appropriate).
>
> The energy that is available from the caps is not the complete energy stored as the voltage will go from 4.2 to 2.8v on each lithium cell. So on my 48v system this means from 54.2 to around 36v which is still an appreciable amount. The leads and battery internal resistance effectively act as resistors so when the motor wants big power, the path of least resistance comes into play and it is the supercapacitor that provides the main power for the peak.As the peak goes down and the supercapacitor voltage drops, the main batteries take over and some current is diverted to the caps to bring them up to voltage. This happens very quickly so in most cases, it is not seen with simple instrumentation.
>
> When I disconnected the super caps, I did see a significant reduction in the regen currents I could achieve:  40-50A instead of the 120-130A . I also saw a far higher voltage drop on the battery packs after hard acceleration. I also saw a slower voltage recovery time as well.
>
> So they are very beneficial. Yes adding more packs will show some similar benefits, but the issue of peak currents is not totally addressed. Yes they are reduced because of the greater load sharing but they are still present. In summary:  Supercaps can harvest more regen current, provide a kinder environment for the batteries and give some improved range. Adding more batteries places less stress on the batteries, will harvest more regen current but nowhere near the level that a supercapcitor will and will give significantly more range. The environment is still not very nice as the peaks will still be there.
>
> Which way to choose depends on the problems that are being addressed and the relative costs of the solutions.
>
> You pays your money and you takes your choice.
>
>
> Steve
>
>> On 28/02/2019 05:55, Cor van de Water via EV wrote:
>> His use of Supercaps was a bandaid: due to the excessive internal resistance of the LiIon batteries that he found, he had to make up a solution to give him the ability for a short power burst (to merge on freeway for example).
>> Supercaps happened to be on sale, so it worked out for him, but they do not add range, just a temporary boost.
>> If you add a parallel pack of batteries, you add both range and double the current (or half the voltage sag) of your pack, so that is typically preferred.
>> I have a similar situation: well-used Nissan Leaf 1st gen batteries that tend to sag quite a bit due to increasing internal resistance, but with 2 packs in parallel, each only sees half the current so the sag is reduced and my range more than doubled.
>> Cor.
>>
>> Sent from Mail for Windows 10
>>
>> From: brucedp5 via EV
>> Sent: Wednesday, February 27, 2019 8:55 PM
>> To: [hidden email]
>> Cc: brucedp5
>> Subject: [EVDL] (metricmind.com links): Supercaps reduce li-ion pack sagging
>>
>> jay sez >Victor Tikhonov (of MetricMind) used a string of 2.7kF Maxwell
>> supercaps<
>>
>> Advanced electric vehicle conversion project - Battery ... - Metric Mind
>> www.metricmind.com/ac_honda/ultracaps.htm
>> The power boost ultracapacitor stack. Manufacturer: Maxwell technologies.
>> Cost: $4,800 (liquidation sale). Ultracaps The LiIon battery I use proved to
>> be a good ...
>>
>> Advanced electric vehicle conversion project - Metric Mind
>> www.metricmind.com/ac_honda/main2.htm
>> ... 10 LEad acid batteries will be replaced with 28 ones, later - with 96
>> LiIon ones (later supplemented with ultracapacitor bank) and then - with 24
>> NiMH ones??
>>
>> FAQ | Metric Mind Corporation
>> www.metricmind.com/education/
>> ... AC drives available for amateur conversions since 2003, first use of
>> supercapacitors, first lithium ion batteries (Honda ACRX), first
>> informational LED lighting, ...
>>
>> High End No Compromise Electric Vehicle Conversion ... - Metric Mind
>> www.metricmind.com/audi/1-initial.htm
>> Apr 6, 2008 - I installed AC drive system, tried several battery types (Lead
>> Acid, Lithium Ion and Nickel Metal Hydride), ultracapacitors and few other
>> novel at ...
>>
>> https://www.google.com/search?q=Metric+Mind+ultracapacitors
>>
>>
>>
>>
>> For EVLN EV-newswire posts use:
>>  http://evdl.org/archive/
>>
>>
>> {brucedp.neocities.org}
>>
>> --
>> Sent from: http://electric-vehicle-discussion-list.413529.n4.nabble.com/
>> _______________________________________________
>> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
>> http://lists.evdl.org/listinfo.cgi/ev-evdl.org
>> Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
>>
>>
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>>
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>

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