# [EVDL] charger question - bypassing batteries



## EVDL List (Jul 27, 2007)

Hey everyone,

I have 50 Calb cells, 2 kW Elcon charger, and a mini bms. My Calbs
shipped in 3 separate boxes. Now that I've had a decent number of
charging cycles, I noticed that one of the batches finishes charging
before the rest. Also, my elcon is supposed to go to yellow when I reach
80% soc and I haven't seen that yet (mini bms shuts charger off because
of a cell limit).

I'd like to charge up the pack and wait for the mini bms to turn off the charger.
I'd then like to bypass the early achiever cells (about 10 cells) and do another
charger cycle.

Will my charger be ok with this? I know it won't give me quite the right
ending curve... I would just charge until I get more cells to a higher voltage.
I wasn't sure if a lower pack voltage seen by the charger would be a bad thing.

thanks,
b-en

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## EVDL List (Jul 27, 2007)

Actually, I found the one I bought from batteryspace.com:


Smart Charger (6.0A) for 3.2V (1cells) LiFePO4 Battery Pack, 100-240VAC, CE listed
CH-LFP3.2V6A	1	$25.95	$25.95

corbin





> corbin dunn <[email protected]> wrote:
> 
> > Hi Ben,
> > A better thing to do is to individually charge the low cells. When I got my TS cells, a few were low and took quite a bit of extra charging (at low amps) to get them up to the same as the others.
> ...


----------



## EVDL List (Jul 27, 2007)

> Ben Jarrett wrote:
> >
> >
> > Hey everyone,
> ...


----------



## EVDL List (Jul 27, 2007)

Hi Ben,
A better thing to do is to individually charge the low cells. When I got my TS cells, a few were low and took quite a bit of extra charging (at low amps) to get them up to the same as the others. 

I got a cheap ~3.6v Lithium charger. If you need help finding one, let me know and I can dig up the model I bought. 

corbin



> Ben Jarrett <[email protected]> wrote:
> 
> >
> >
> ...


----------



## EVDL List (Jul 27, 2007)

Change the algorithm in the charger to the next higher voltage and recharge
letting the BMS control the charger. The charger is shutting off too soon.

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## EVDL List (Jul 27, 2007)

Willie's solution is good too, provided you have a charger setup that way. 

Another alternative is to connect all the cells in parallel; this makes the total Ah rating be the additive some of each individual cells Ah rating, and the voltage is equal to a single cell's voltage. However, I choose not to do this approach for several reasons:
1. I would have to rewire my pack (even temporarily using low-current capable wires), which would have been a pain.
2. It would still take a while to get all the cells equalized, since one has to put in a bunch of amp-hours for the entire pack in order to reach full charge.

The nice thing about using a small 3.2v LifePo4 charger on single cells is that the charger is essentially a single-cell BMS, and you shouldn't be able to overcharge that single cell with it (I say shouldn't, because who knows what crazy things could happen).

corbin




> Willie McKemie wrote:
> 
> > On Fri, Jun 15, 2012 at 11:11:11PM -0500, Ben Jarrett wrote:
> >>
> ...


----------



## EVDL List (Jul 27, 2007)

I am using a Sky Charger that I bought from Xheli through Amazon. It looks
like it isn't through Amazon any more but can be obtained from xheli.com
directly.

http://www.xheli.com/skychb6durcc.html?gclid=CPWVkZec07ACFaYaQgodw1c14g

This charger supports lead-acid, LiFePO4, NiCd, NiMH. It is intended for RC
models, but works really well to charge 1-6 cells on our cars. It has an
output of up to 5A or 50W. Costs about $55.

Mike

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of corbin dunn
> Sent: Saturday, June 16, 2012 10:18 AM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] charger question - bypassing batteries
> 
> Willie's solution is good too, provided you have a charger setup that way.
> 
> Another alternative is to connect all the cells in parallel; this makes
the total
> Ah rating be the additive some of each individual cells Ah rating, and the
> voltage is equal to a single cell's voltage. However, I choose not to do
this
> approach for several reasons:
> 1. I would have to rewire my pack (even temporarily using low-current
> capable wires), which would have been a pain.
> 2. It would still take a while to get all the cells equalized, since one
has to put
> in a bunch of amp-hours for the entire pack in order to reach full charge.
> 
> The nice thing about using a small 3.2v LifePo4 charger on single cells is
that
> the charger is essentially a single-cell BMS, and you shouldn't be able to
> overcharge that single cell with it (I say shouldn't, because who knows
what
> crazy things could happen).
> 
> corbin
> 
> 
>


> Willie McKemie wrote:
> >
> > > On Fri, Jun 15, 2012 at 11:11:11PM -0500, Ben Jarrett wrote:
> > >>
> ...


----------



## EVDL List (Jul 27, 2007)

I forgot to mention in the last post: One of the things I really like about
the Sky Charger is the information display. As it's charging, it shows how
many amps it's charging at and how many Ah (milli Ah actually) it has put
into the cells. This lets you know exactly how far from balanced your cells
really are. When I first used the charger, I had some cells that were 20%
low!

Also, even if you charge 5 or 6 cells in a string (helps speed things up),
it charges at a low enough current that your MiniBMS shunts can probably
keep up. For the first balancing charge, though, I did one cell at a time.
I think I would recommend doing that. Once things are closer into balance,
you can charge several cells at a time. 

My experience with the Elcon charger on my pack is that it won't go into its
finishing stage (LED turns yellow), until 1/2 to 2/3 of the cells are
starting to shunt. I found that I needed to go through the cycle of
charging lower cells with the Sky Charger a couple of times before the
charger could completely finish the charge cycle.

Mike

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of Mike Nickerson
> Sent: Saturday, June 16, 2012 10:55 AM
> To: 'Electric Vehicle Discussion List'
> Subject: Re: [EVDL] charger question - bypassing batteries
> 
> I am using a Sky Charger that I bought from Xheli through Amazon. It
looks
> like it isn't through Amazon any more but can be obtained from xheli.com
> directly.
> 
> http://www.xheli.com/skychb6durcc.html?gclid=CPWVkZec07ACFaYaQgodw
> 1c14g
> 
> This charger supports lead-acid, LiFePO4, NiCd, NiMH. It is intended for
RC
> models, but works really well to charge 1-6 cells on our cars. It has an
output
> of up to 5A or 50W. Costs about $55.
> 
> Mike
> 

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## EVDL List (Jul 27, 2007)

> Ben Jarrett wrote:
> > I have 50 Calb cells, 2 kW Elcon charger, and a mini bms...
> > I noticed that one of the batches finishes charging
> > before the rest. Also, my elcon is supposed to go to yellow when I reach
> ...


----------



## EVDL List (Jul 27, 2007)

Hi Lee,

I have similar cells, BMS and charger to Ben's. The system is not as
intelligent as you describe. The charger decides on its own (from the
current charging voltage and its built-in program) when to switch to lower
current. It won't do that unless the cells are pretty well matched. The
BMS doesn't have any communication with the charger about cells at the
shunting level.

Again, as the first cell reaches its overvoltage limit, the BMS doesn't
inform the charger, but instead cuts power to the charger through an AC
relay. 

The MiniBMS system and Elcon charger combination will work fine once the
cells are balanced. However, in my experience, they are not sufficient to
bring the system into balance if it is very far off. The charger is simply
charging with too much current still if the cells are significantly out of
balance.

Mike

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of Lee Hart
> Sent: Saturday, June 16, 2012 6:48 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] charger question - bypassing batteries
> 


> > Ben Jarrett wrote:
> > > I have 50 Calb cells, 2 kW Elcon charger, and a mini bms...
> > > I noticed that one of the batches finishes charging before the rest.
> > > Also, my elcon is supposed to go to yellow when I reach 80% soc and I
> ...


----------



## EVDL List (Jul 27, 2007)

> Mike Nickerson wrote:
> > Hi Lee,
> >
> > I have similar cells, BMS and charger to Ben's. The system is not as
> ...


----------



## EVDL List (Jul 27, 2007)

So in my case, all 50 of my Calb 130 Ah cells started at 3.2 volts. The charger was
setup by the factory for my pack (supposedly). It has a sticker on the side saying
it's for 180V max LiFePo4 pack. So I charge my pack and here's what happens:

* After charging for a few hours on 120V (about 7 amps into the pack), I have some
cells that start reaching 3.5 Volts.
* At this point, the mini bms starts shunting these cells. I'm still getting
around 7amps into the pack.
* If one of these cells hits 3.6 Volts, the mini bms shuts off the charger
(that's what's happening now).
* For me, I have 10 cells that are shunting when the mini-bms turns off the charger.
* Most of the other cells are at 3.4V (for Lithium, it's hard to know what the SOC
is from the voltage, but they should be pretty well charged).

So what I'd like to do is:
* Charge my pack until the mini bms shuts off the charger.
* Bypass the 10 early cells (I have a 2 gage bypass cable for emergencies)
* Start the charger again
* Allow the mini bms to shut off the charger
* See if I'm top balanced yet.

Can I damage anything if I hook up my Elcon 2kW charger (that's been "programmed"
for 50 cells) to 40 cells and let it charge? This is one question I still don't have
an answer for. Maybe someone out there knows.

I still could get a single cell charger to finish things off, but I'm looking for
a good way to get closer.

thanks!
-ben




> Lee Hart wrote:
> 
> > On 6/16/2012 8:18 PM, Mike Nickerson wrote:
> >> I have similar cells, BMS and charger to Ben's. The system is not as
> ...


----------



## EVDL List (Jul 27, 2007)

You could just wait a few minutes and restart the charger. It should run
for a little bit and then get shut off by the BMS again. Each time the low
cells are getting closer to full. If they really are at 3.4v when the
charger it cut off then they aren't too far behind.

You might just want to put a resistor across the few high cells and then
run the charger again. That would likely be cheaper and you know your
charger won't mind.



> Ben Jarrett wrote:
> 
> >
> >
> ...


----------



## EVDL List (Jul 27, 2007)

If the charger never reaches its 80% indication
because one of the cells gets too high and the
BMS shuts the charger off, then I would expect that
it will help to set the charger voltage *lower* until
it is the *charger* that shuts off the charging, not 
the emergency shutoff from the BMS because a cell goes
over limit.
In fact, with the charger at (much) lower voltage
you would allow any high cells to be shunted for a
while by the BMS so all high cells are pushed to lower SoC
until the point that you might be able to turn the
charger up a little when after a long period of shunting
all cells stop shunting because the total pack voltage
is divided more equally and all cells stay below the
shunting voltage. If that happens then you can turn the
charger up just a tad until you reach the point that
the lowest cell is almost shunting while all other cells
are barely shunting. That gives the lowest voltage and
the lowest waste of energy while making sure that all
of your pack will get balanced if you charge long enough.
It has the risk of over-charging cells at too low current
so it is wise to not charge to this point very often,
only when you absolutely need the max energy from your pack
(very long trip) or an occasional balance charge, once 
a month or so. At all other charges you might want to 
shut off the charger when it reaches 80% SoC or so to 
get the longest life from your pack.

Hope this clarifies,

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water XoIP: +31877841130
Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203 

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Cruisin
Sent: Saturday, June 16, 2012 5:45 AM
To: [email protected]
Subject: Re: [EVDL] charger question - bypassing batteries

Change the algorithm in the charger to the next higher voltage and
recharge letting the BMS control the charger. The charger is shutting
off too soon.

--
View this message in context:
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stion-bypassing-batteries-tp4655708p4655722.html
Sent from the Electric Vehicle Discussion List mailing list archive at
Nabble.com.

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## EVDL List (Jul 27, 2007)

> Ben Jarrett wrote:
> > So in my case, all 50 of my Calb 130 Ah cells started at 3.2 volts.
> 
> That means they were initially somewhere between 20% and 80% state of
> ...


----------



## EVDL List (Jul 27, 2007)

When I set up my 40 CALB 100Ah cells with miniBMS, it took me almost 2
weeks of charging to get the whole pack to the point that all cells were
above 3.5 v (all red LED's lit) at the same time. I used a variety of
chargers from an adjustable power supply (one that Dimitri recommended)
which can charge individual cells, or small groups of cells, a 12v charger,
and a 24v charger for groups of cells. I would use a 12v DC 50 watt bulb
and a 12v load tester to drain the first ones to light up while charging.
Once they all reached that point, I haven't had to do anything. I just
periodically check end of charge to make sure that they still all light up
before one hits the shut off point. It has been a little over 6 months, and
I haven't seen any real variation yet; cells are all within 0.01 of each
other.
Michael B



> Lee Hart <[email protected]> wrote:
> 
> > Ben Jarrett wrote:
> > > So in my case, all 50 of my Calb 130 Ah cells started at 3.2 volts.
> ...


----------



## EVDL List (Jul 27, 2007)

> Ben Jarrett <[email protected]> wrote:
> 
> >
> > So what I'd like to do is:
> ...


----------



## EVDL List (Jul 27, 2007)

The last time I installed my cells, I charged them each individually up to =
3.60v with a PowerLab 6 charger. I installed them all, drove a bit, then=
charged them with my vehicle charger. My charger shuts off at 3.5vpc av=
erage, and there were 10 or so MiniBMS red lights that were not on at end o=
f charge (on mine, the lights come on at ~3.47v). I figured they had to =
be pretty close since I had manually charged them all to 3.60v, and just le=
ft it be. About 10 discharge/charge cycles later, I checked. The same=
cells were still not lighting up the MiniBMS lights. At that point I ma=
nually brought them up with a power supply one cell at a time, and found th=
ey required less than 1ah to get up to shunting (typical was about 15 minut=
es at 2a). I don't think the MiniBMS is able to handle much balancing at=
all (at least in my case when I'm only charging to 3.5vpc), but at least i=
t will make up for any cell balance difference due to it's own power draw.


Now all 48 lights are on at end of charge. I've also noted that over the=
last few months, the same lights come on in the same order every time, and=
the same cell is always the last one to light up. Not a lot of balancin=
g going on I don't think.

fwiw, it's easy to balance them with a power supply. You don't have to d=
isconnect anything, just set it to 3.6v open voltage, alligator clip it acr=
oss the single cell, and turn up the current to charge until the red light =
on the MiniBMS comes on. You are now at 3.47v, monitor the cell till i g=
ets to where you want it to be (in my case 3.5v), then shut off the power s=
upply.

Check again next charge cycle and repeat as necessary.

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## EVDL List (Jul 27, 2007)

> Lee Hart <[email protected]> wrote:
> > ...
> > It sounds like there is a fundamental problem with how the mini-BMS and
> > this Elcon charger work. Each one is assuming that the other is doing
> ...


----------



## EVDL List (Jul 27, 2007)

FWIW,
A top balancer that really works automatically, every time you charge means
you never have to do anything to the batteries but use them to move the car.


In essence this means as most of us have been saying, a balancing system
with LiFePO4 is a good idea.


Sincerely,
Mark Grasser
=



-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of David Ladd
Sent: Tuesday, June 19, 2012 2:31 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] charger question - bypassing batteries

The last time I installed my cells, I charged them each individually up to
3.60v with a PowerLab 6 charger. I installed them all, drove a bit, then
charged them with my vehicle charger. My charger shuts off at 3.5vpc
average, and there were 10 or so MiniBMS red lights that were not on at end
of charge (on mine, the lights come on at ~3.47v). I figured they had to=
be
pretty close since I had manually charged them all to 3.60v, and just left
it be. About 10 discharge/charge cycles later, I checked. The same ce=
lls
were still not lighting up the MiniBMS lights. At that point I manually
brought them up with a power supply one cell at a time, and found they
required less than 1ah to get up to shunting (typical was about 15 minutes
at 2a). I don't think the MiniBMS is able to handle much balancing at all
(at least in my case when I'm only charging to 3.5vpc), but at least it will
make up for any cell balance difference due to it's own power draw.


Now all 48 lights are on at end of charge. I've also noted that over the
last few months, the same lights come on in the same order every time, and
the same cell is always the last one to light up. Not a lot of balancing
going on I don't think.

fwiw, it's easy to balance them with a power supply. You don't have to
disconnect anything, just set it to 3.6v open voltage, alligator clip it
across the single cell, and turn up the current to charge until the red
light on the MiniBMS comes on. You are now at 3.47v, monitor the cell ti=
ll
i gets to where you want it to be (in my case 3.5v), then shut off the power
supply.

Check again next charge cycle and repeat as necessary.

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## EVDL List (Jul 27, 2007)

I think that the MiniBMS is getting an unfair rap from those who may not have
a sufficient understanding of how a BMS works; so I'd like to come to its
defense.

The MiniBMS / ElCOn combination will work just fine, if you just leave it
alone to do its job, which it knows how to do and do well (thank you very
much). 

The pack was grossly unbalanced to start with, because no pre-balancing was
done (http://liionbms.com/php/wp_parallel_balance.php); so it will take a
long time for the MiniBMS to balance it. But balance it will, as long as you
don't frig with it. 

How?
While the pack is unbalanced, the BMS will turn the charger on and off, at a
duty cycle that is equal to the ratio of the balance current over the
charger output current: i,e,: the AVERAGE current out of the charger is
exactly equal to the balance current. No, the charger will not "overload the
BMS balance circuit". All the while, the MininBMS will burn off charge off
the most charged cells, to make room for more charge in all cells. Totally
normal. 

For more details, I offer this video:
http://www.youtube.com/watch?v=K4Dz3XrgluM

Yes, if you can't afford to wait, you can discharge or charge some cells.
But, let me warn you, I have seen cells damaged by people doing this while
distracted.

The problem is not the MiniBMS. The problem is not the ElCon. The problem is
misplaced concerns. If I may make a suggestion: instead of trying to offer
solutions, it may be more productive to spend time reading up on how a BMS
works.

Dimitri did so. He understands what a BMS needs to do, and how, as shown by
how well the MiniBMS does its job.



-----
Davide Andrea
Elithion 
--
View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/charger-question-bypassing-batteries-tp4655708p4655838.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.

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## EVDL List (Jul 27, 2007)

Hi Davide,

Thanks for correcting the info given.
I am used to see a "BMS" which simply turns off
the charger when the first cell hits max, so then it
is done (no balancing even, only Monitoring)
so it may be that I was biased and did not even consider
the operation of the mini-BMS as you describe:

- charge until the first cell hits high voltage cutoff
(the BMS will already start shunting at a lower level)
- with the charger turned off the BMS will continue to
shunt the high cells until the higest one has dropped
below threshold, then the cycle repeats. 

Not sure how long this will go on, whether eventually
the charger will not be turned off by the BMS and thus
it will eventually timeout with all cells shunting
or that there is another termination condition.

Regards,

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water XoIP: +31877841130
Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203 

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Elithion
Sent: Tuesday, June 19, 2012 9:43 PM
To: [email protected]
Subject: Re: [EVDL] charger question - bypassing batteries

I think that the MiniBMS is getting an unfair rap from those who may not
have a sufficient understanding of how a BMS works; so I'd like to come
to its defense.

The MiniBMS / ElCOn combination will work just fine, if you just leave
it alone to do its job, which it knows how to do and do well (thank you
very much). 

The pack was grossly unbalanced to start with, because no pre-balancing
was done (http://liionbms.com/php/wp_parallel_balance.php); so it will
take a long time for the MiniBMS to balance it. But balance it will, as
long as you don't frig with it. 

How?
While the pack is unbalanced, the BMS will turn the charger on and off,
at a duty cycle that is equal to the ratio of the balance current over
the charger output current: i,e,: the AVERAGE current out of the charger
is exactly equal to the balance current. No, the charger will not
"overload the BMS balance circuit". All the while, the MininBMS will
burn off charge off the most charged cells, to make room for more charge
in all cells. Totally normal. 

For more details, I offer this video:
http://www.youtube.com/watch?v=K4Dz3XrgluM

Yes, if you can't afford to wait, you can discharge or charge some
cells.
But, let me warn you, I have seen cells damaged by people doing this
while distracted.

The problem is not the MiniBMS. The problem is not the ElCon. The
problem is misplaced concerns. If I may make a suggestion: instead of
trying to offer solutions, it may be more productive to spend time
reading up on how a BMS works.

Dimitri did so. He understands what a BMS needs to do, and how, as shown
by how well the MiniBMS does its job.



-----
Davide Andrea
Elithion
--
View this message in context:
http://electric-vehicle-discussion-list.413529.n4.nabble.com/charger-que
stion-bypassing-batteries-tp4655708p4655838.html
Sent from the Electric Vehicle Discussion List mailing list archive at
Nabble.com.

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## EVDL List (Jul 27, 2007)

My MiniBMS system doesn't do the cycling (unless a human is part of the
circuit to turn things back on). When the MiniBMS control board alerts
while charging, it sends a signal to turn off the AC solid state relay.
That relay isn't signaled to come back on (by the MiniBMS control board)
until the control board sees 12V (from the key switching on). It would be
possible to turn that on and off several times in a row, but I find it
easier to simply pull out the RC charger and top up the low cells. Once
balanced, I'm done with that until I split the pack.

Now, my car is running older MiniBMS modules (about 2 years old), so it's
possible they have been improved since then.

Mike

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of Cor van de Water
> Sent: Wednesday, June 20, 2012 12:12 AM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] charger question - bypassing batteries
> 
> Hi Davide,
> 
> Thanks for correcting the info given.
> I am used to see a "BMS" which simply turns off the charger when the first
> cell hits max, so then it is done (no balancing even, only Monitoring) so
it may
> be that I was biased and did not even consider the operation of the mini-
> BMS as you describe:
> 
> - charge until the first cell hits high voltage cutoff
> (the BMS will already start shunting at a lower level)
> - with the charger turned off the BMS will continue to
> shunt the high cells until the higest one has dropped
> below threshold, then the cycle repeats.
> 
> Not sure how long this will go on, whether eventually the charger will not
be
> turned off by the BMS and thus it will eventually timeout with all cells
> shunting or that there is another termination condition.
> 
> Regards,
> 
> Cor van de Water
> Chief Scientist
> Proxim Wireless Corporation http://www.proxim.com
> Email: [email protected] Private: http://www.cvandewater.com
> Skype: cor_van_de_water XoIP: +31877841130
> Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203
> 
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of Elithion
> Sent: Tuesday, June 19, 2012 9:43 PM
> To: [email protected]
> Subject: Re: [EVDL] charger question - bypassing batteries
> 
> I think that the MiniBMS is getting an unfair rap from those who may not
> have a sufficient understanding of how a BMS works; so I'd like to come to
its
> defense.
> 
> The MiniBMS / ElCOn combination will work just fine, if you just leave it
alone
> to do its job, which it knows how to do and do well (thank you very much).
> 
> The pack was grossly unbalanced to start with, because no pre-balancing
was
> done (http://liionbms.com/php/wp_parallel_balance.php); so it will take a
> long time for the MiniBMS to balance it. But balance it will, as long as
you
> don't frig with it.
> 
> How?
> While the pack is unbalanced, the BMS will turn the charger on and off, at
a
> duty cycle that is equal to the ratio of the balance current over the
charger
> output current: i,e,: the AVERAGE current out of the charger is exactly
equal
> to the balance current. No, the charger will not "overload the BMS balance
> circuit". All the while, the MininBMS will burn off charge off the most
charged
> cells, to make room for more charge in all cells. Totally normal.
> 
> For more details, I offer this video:
> http://www.youtube.com/watch?v=K4Dz3XrgluM
> 
> Yes, if you can't afford to wait, you can discharge or charge some cells.
> But, let me warn you, I have seen cells damaged by people doing this while
> distracted.
> 
> The problem is not the MiniBMS. The problem is not the ElCon. The problem
> is misplaced concerns. If I may make a suggestion: instead of trying to
offer
> solutions, it may be more productive to spend time reading up on how a BMS
> works.
> 
> Dimitri did so. He understands what a BMS needs to do, and how, as shown
> by how well the MiniBMS does its job.
> 
> 
> 
> -----
> Davide Andrea
> Elithion
> --
> View this message in context:
> http://electric-vehicle-discussion-list.413529.n4.nabble.com/charger-que
> stion-bypassing-batteries-tp4655708p4655838.html
> Sent from the Electric Vehicle Discussion List mailing list archive at
> Nabble.com.
> 
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere. Thanks.
> |
> | REPLYING: address your message to [email protected] only.
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> 
> _______________________________________________
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## EVDL List (Jul 27, 2007)

> Mike Nickerson wrote:
> > My MiniBMS system doesn't do the cycling (unless a human is part of the
> > circuit to turn things back on). When the MiniBMS control board alerts
> > while charging, it sends a signal to turn off the AC solid state relay.
> ...


----------



## EVDL List (Jul 27, 2007)

Mike Nickerson wrote
> 
> My MiniBMS system doesn't do the cycling 
> 

You are right; I was wrong.

The MiniBMS balancing guide
(http://minibms.mybigcommerce.com/template/files/How%20to%20perform%20initial%20LiFePo4%20battery%20pack%20balancing%20using%20MiniBMS.pdf)
states 
"If BMS shut the charger, you must cycle Ignition key to reset the BMS back
to normal
and start the charger again."
I am shocked, and truly, sorely disappointed.

I owe you all an apology for having such strong belief that the MiniBMS
operated as any good BMS does. 
If you wish, go ahead and keep on bashing the MiniBMS, as you were. I'll
step out of this fray.

-----
Davide Andrea
Elithion 
--
View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/charger-question-bypassing-batteries-tp4655708p4655854.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.

_______________________________________________
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## EVDL List (Jul 27, 2007)

I didn't see anyone bashing MiniBMS.? At least not until your post... =
To my knowledge it works just as advertised. If you start with your c=
ells balanced, it will keep them balanced (some will argue that you don't n=
eed any balancing to do this, but you can't deny that the small balancing t=
he MiniBMS provides will). It will also alert you to a high or low cell,=
and can be set up to cut off the charger or reduce your throttle. It is=
a basic level of cell *protection* just as is intended. As you linked t=
o, the initial cell balancing guide is right there on their website. It =
involves external inputs of either charging or discharging individual cells=
. 

But once you are top balanced, THEN it is set it and forget it. It's not=
like this manual balancing is something that has to be done every month, j=
ust one time when the pack is assembled (or re-assembled after testing cell=
s, in my case).

david.
http://www.evalbum.com/4021



----- Original Message -----
> From: Elithion <[email protected]>
snip.
> You are right; I was wrong.
> =

> The MiniBMS balancing guide
> (http://minibms.mybigcommerce.com/template/files/How%20to%20perform%20ini=
tial%20LiFePo4%20battery%20pack%20balancing%20using%20MiniBMS.pdf)
> states =

> "If BMS shut the charger, you must cycle Ignition key to reset the BMS ba=
ck
> to normal
> and start the charger again."
> I am shocked, and truly, sorely disappointed.
> =

> I owe you all an apology for having such strong belief that the MiniBMS
> operated as any good BMS does. =

> If you wish, go ahead and keep on bashing the MiniBMS, as you were. I'll
> step out of this fray.
> =

> -----
> Davide Andrea
> Elithion =

>

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
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----------



## EVDL List (Jul 27, 2007)

Exactly. Very well stated. The MiniBMS has been working exactly like that
for me also.

Mike

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of David Ladd
> Sent: Wednesday, June 20, 2012 7:30 AM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] charger question - bypassing batteries
> =

> I didn't see anyone bashing MiniBMS.? At least not until your post... =
To
my
> knowledge it works just as advertised. If you start with your cells
balanced, it
> will keep them balanced (some will argue that you don't need any balancing
> to do this, but you can't deny that the small balancing the MiniBMS
provides
> will). It will also alert you to a high or low cell, and can be set up=
to
cut off the
> charger or reduce your throttle. It is a basic level of cell *protecti=
on*
just as
> is intended. As you linked to, the initial cell balancing guide is rig=
ht
there on
> their website. It involves external inputs of either charging or
discharging
> individual cells.
> =

> But once you are top balanced, THEN it is set it and forget it. It's n=
ot
like this
> manual balancing is something that has to be done every month, just one
> time when the pack is assembled (or re-assembled after testing cells, in
my
> case).
> =

> david.
> http://www.evalbum.com/4021
> =



_______________________________________________
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| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
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----------



## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> > On 6/20/2012 5:23 AM, Willie McKemie wrote:
> > > I was surprised to read that (perhaps) miniBMS cycles the charger. I
> > > am using EVPower controllers and mostly miniBMS cell modules. Several
> ...


----------



## EVDL List (Jul 27, 2007)

> Elithion wrote:
> > The MiniBMS balancing guide states "If BMS shut the charger, you must
> > cycle Ignition key to reset the BMS back to normal and start the
> > charger again." I am shocked, and truly, sorely disappointed.
> ...


----------



## EVDL List (Jul 27, 2007)

Instead of having the BMS automatically cycle the charger, you could
do an initial balance by putting a light bulb or similar load between
the charger and the battery so the charger runs in voltage limit with
a low enough output current that the mini-BMS can bypass the entire
current.

Once the pack is balanced, this shouldn't be necessary; hopefully
0.2Ah/charge is enough to keep the pack balanced, and you can get more
balancing by having the charger voltage set so the current tapers off
when the pack voltage is 3.5-3.6 V/cell average.

-Morgan LaMoore



> Willie McKemie <[email protected]> wrote:
> > ...
> > Maybe so. But it is a highly desirable feature from my perspective.
> > I believe Davide's BMSs cycle the chargers. Just install a
> ...


----------



## EVDL List (Jul 27, 2007)

I have always thought that the thing to do would be this: When the first BMS
activates the large charger gets switched off and a 2 or 3 amp current
limited charger switches on. Because it is current limited at 2 or 3 amps
it's charge voltage isn't all that important but probably should be
calculated at something less than 4.0 volts per cell just in case. At the
point when all BMSs activate this charger would then be switched off also.
If done every time the pack is charged it should only take a few minutes to
balance the whole pack.


Sincerely,
Mark Grasser
=



-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Morgan LaMoore
Sent: Wednesday, June 20, 2012 6:53 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] charger question - bypassing batteries

Instead of having the BMS automatically cycle the charger, you could do an
initial balance by putting a light bulb or similar load between the charger
and the battery so the charger runs in voltage limit with a low enough
output current that the mini-BMS can bypass the entire current.

Once the pack is balanced, this shouldn't be necessary; hopefully
0.2Ah/charge is enough to keep the pack balanced, and you can get more
balancing by having the charger voltage set so the current tapers off when
the pack voltage is 3.5-3.6 V/cell average.

-Morgan LaMoore



> Willie McKemie <[email protected]> wrote:
> > ...
> > Maybe so. But it is a highly desirable feature from my perspective.
> > I believe Davide's BMSs cycle the chargers. Just install a =
> ...


----------



## EVDL List (Jul 27, 2007)

You know, I have one of the MiniBMS master boards that I am using for 
testing. If you really want the ability to watch for regs going on you 
could either:

1) Install optoisolators on the red/green LED outputs and drive a second 
loop with them.

2) Install thermal sensors on the resistors. They get *hot* when they 
are regulating.

Either would allow you to build a charger banking tool to slow the 
charge cycle.

Chris


On 6/20/2012 8:55 PM, Mark Grasser wrote:
> I have always thought that the thing to do would be this: When the first BMS
> activates the large charger gets switched off and a 2 or 3 amp current
> limited charger switches on. Because it is current limited at 2 or 3 amps
> it's charge voltage isn't all that important but probably should be
> calculated at something less than 4.0 volts per cell just in case. At the
> point when all BMSs activate this charger would then be switched off also.
> If done every time the pack is charged it should only take a few minutes to
> balance the whole pack.
>
>
> Sincerely,
> Mark Grasser
>
>
>
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On Behalf
> Of Morgan LaMoore
> Sent: Wednesday, June 20, 2012 6:53 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] charger question - bypassing batteries
>
> Instead of having the BMS automatically cycle the charger, you could do an
> initial balance by putting a light bulb or similar load between the charger
> and the battery so the charger runs in voltage limit with a low enough
> output current that the mini-BMS can bypass the entire current.
>
> Once the pack is balanced, this shouldn't be necessary; hopefully
> 0.2Ah/charge is enough to keep the pack balanced, and you can get more
> balancing by having the charger voltage set so the current tapers off when
> the pack voltage is 3.5-3.6 V/cell average.
>
> -Morgan LaMoore
>
>


> Willie McKemie <[email protected]> wrote:
> >> ...
> >> Maybe so. But it is a highly desirable feature from my perspective.
> >> I believe Davide's BMSs cycle the chargers. Just install a
> ...


----------



## EVDL List (Jul 27, 2007)

Hey everyone,

thanks for all the comments. I've been pretty busy at work and working on my jeep
so I didn't have a chance to email the group. The summary is that the mini bms
can do some balance, but not much if the charger is still cranking out 7 amps.

I think what I need to do is buy a charger for one cell, charge each cell
to 3.6 volts. Then let my mini bms handle things from there.

thanks!!!
-ben



> Morgan LaMoore wrote:
> 
> > Instead of having the BMS automatically cycle the charger, you could
> > do an initial balance by putting a light bulb or similar load between
> ...


----------

