# Re: [EVDL] charge in parallel, discharge in series



## EVDL List (Jul 27, 2007)

*Re: [EVDL] charge in parallel, discharge in series*

I have not had a lot of experience here but I think I am doing this and it
appears to be working. I have twelve 12V batteries in 2 72V strings. Each
battery has its own charger. I am using Dual-Pro Lil 3 chargers each
charger will charge 3 batteries and thus I have 4 of them.

They seem to charge the batteries to the same level and if I running a test
on say two batteries the chargers bring them all back to the same level.
The batteries not used in the test will immediately go to float mode and
those I used may take a few hours to reach their charge, depending on how
long I tested. I have been lightly testing for 3 months now.

So the batteries are connected to the charger and in a 72V string at the
same time. That does not appear to be a problem.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of [email protected]
Sent: Wednesday, January 23, 2008 12:29 PM
To: [email protected]
Subject: [EVDL] charge in parallel, dischargein series


This has surely come up before but i cant find it in the archives so excuse
me
for asking:

Is it okay to charge in parallel and discharge in series? 
Wouldnt this be a simple way to balance?

With a single DPDT switch for each battery one could connect its terminals
either in charging topology 
(all batt terminals connected in parallel to terminals of the charger [which
is
set to charge at a single cell voltage] )
or in discharging topology 
(the +,- terminals of each cell connected to the next upper and lower cells
repectively)



jeremy 
Jeremy Rutman
Technion Physics Dep't.
Haifa 32000 Israel
phone 972 4 8293669
fax 972 4 8295755

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] charge in parallel, discharge in series*



> On 23 Jan 2008 at 20:55, David Hrivnak wrote:
> 
> > I have not had a lot of experience here but I think I am doing this and it
> > appears to be working. I have twelve 12V batteries in 2 72V strings. Each
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] charge in parallel, discharge in series*

Hi David,

I also use individual 12 volt charging on 48 volt
utility trucks. I tried the Dual Pro. The 4 bank SE
model. Had some trouble with it. Did some testing. 
Results were disappointing. Went back to the Minn
Kota multiple chargers. They work great.

Regards,

Jeff M




> --- David Hrivnak <[email protected]> wrote:
> 
> > I have not had a lot of experience here but I think
> > I am doing this and it
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] charge in parallel, discharge in series*

Of course the original post had nothing to do with modular charging which uses multiple chargers and leaves the series string intact. It was a question about putting all the batteries in parallel then charging them with a single charger.


> Date: Fri, 25 Jan 2008 08:01:04 -0800
> From: [email protected]
> To: [email protected]
> Subject: Re: [EVDL] charge in parallel, discharge in series
>
>
> Hi David,
>
> I also use individual 12 volt charging on 48 volt
> utility trucks. I tried the Dual Pro. The 4 bank SE
> model. Had some trouble with it. Did some testing.
> Results were disappointing. Went back to the Minn
> Kota multiple chargers. They work great.
>
> Regards,
>
> Jeff M
>
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## EVDL List (Jul 27, 2007)

*Re: [EVDL] charge in parallel, discharge in series*

Jeff what trouble with you have with Dual-Pro? I did have one fail but they
were great on the replacement. Just one call and I had it in 2 days and
they gave me the label to send it back postage free.

To be fair I was having it charger two batteries per lead and now I have one
lead per battery. I only have a week of operation so it remains to be seen
if it will work long term but they do seen rugged enough.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Jeff Major
Sent: Friday, January 25, 2008 11:01 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] charge in parallel, discharge in series


Hi David,

I also use individual 12 volt charging on 48 volt
utility trucks. I tried the Dual Pro. The 4 bank SE
model. Had some trouble with it. Did some testing. 
Results were disappointing. Went back to the Minn
Kota multiple chargers. They work great.

Regards,

Jeff M




> --- David Hrivnak <[email protected]> wrote:
> 
> > I have not had a lot of experience here but I think
> > I am doing this and it
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] charge in parallel, discharge in series*

Hi David,

At the risk of Damon telling us that we talk of
modular charging whereas the thread is about parallel
charging, I will respond. My previous post was a
reply to you, so I kept the same thread. I realize it
is not exactly parallel charging. But then a lot of
posts deviate from the original thread subject. I
think modular charging is close enough to parallel
charging to be considered. In fact, it accomplishes
the desired result with potentially greater
reliability and lower cost.

WRT to the Dual Pro, I found that my 10 amp rated
chargers typically ran at 5 to 6 amps. Even with a
deeply discharged battery, I saw 9 amps for a few
seconds, with a quick drop to about 5 or 6. This
leads me to believe that they may not fully charge the
batteries in a single shift.

Also, I do not like the charge algorithm. I don't
remember the figures, but it was something along the
lines that they went to 13.5 volts, stopped, and then
occasionally cycled. In my mind, not a full charge,
and no float. Before I took a close look at the volts
and amps, I threw one on a vehicle an used it for
about 6 months. I can't say it was the cause, but
those batteries aren't much good any more.

I also saw moisture on the inside of the LED lenses. 
And what appeared to be a crack on two corners of the
case. The company did send a replacement in short
order. They also claim a "program change". They told
me that their engineer would visit and clear up all my
questions. After I made arrangements, that day I
learned he was too busy.

I put the Dual Pro charger and the murdered batteries
in an old vehicle which is rarely used and went to the
Minn Kota chargers in the truck I use often. For
production, I am sticking with Minn Kota. They
deliver rated amps for most of the charge cycle and
seem to have a logical algorithm. Also appear to be a
high quality. The Minn Kota cost a few bucks more,
but I think worth it.

Regards,

Jeff M



> --- David Hrivnak <[email protected]> wrote:
> 
> > Jeff what trouble with you have with Dual-Pro? I
> > did have one fail but they
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] charge in parallel, discharge in series*

I thank you for a clear explination. I also searched the archives and saw some of the problems people have seen in modular charging. So far my system is looking good but it looks like I will need to keep an eye on things. If a bank dies the there can be serious battery damage.

So far the Dual-Pro have charged over night which in reality is all the current I need at least at the moment.

-----Original Message-----
From: Jeff Major <[email protected]>
Sent: Monday, January 28, 2008 12:04 PM
To: Electric Vehicle Discussion List <[email protected]>
Subject: Re: [EVDL] charge in parallel, discharge in series


Hi David,

At the risk of Damon telling us that we talk of
modular charging whereas the thread is about parallel
charging, I will respond. My previous post was a
reply to you, so I kept the same thread. I realize it
is not exactly parallel charging. But then a lot of
posts deviate from the original thread subject. I
think modular charging is close enough to parallel
charging to be considered. In fact, it accomplishes
the desired result with potentially greater
reliability and lower cost.

WRT to the Dual Pro, I found that my 10 amp rated
chargers typically ran at 5 to 6 amps. Even with a
deeply discharged battery, I saw 9 amps for a few
seconds, with a quick drop to about 5 or 6. This
leads me to believe that they may not fully charge the
batteries in a single shift.

Also, I do not like the charge algorithm. I don't
remember the figures, but it was something along the
lines that they went to 13.5 volts, stopped, and then
occasionally cycled. In my mind, not a full charge,
and no float. Before I took a close look at the volts
and amps, I threw one on a vehicle an used it for
about 6 months. I can't say it was the cause, but
those batteries aren't much good any more.

I also saw moisture on the inside of the LED lenses. 
And what appeared to be a crack on two corners of the
case. The company did send a replacement in short
order. They also claim a "program change". They told
me that their engineer would visit and clear up all my
questions. After I made arrangements, that day I
learned he was too busy.

I put the Dual Pro charger and the murdered batteries
in an old vehicle which is rarely used and went to the
Minn Kota chargers in the truck I use often. For
production, I am sticking with Minn Kota. They
deliver rated amps for most of the charge cycle and
seem to have a logical algorithm. Also appear to be a
high quality. The Minn Kota cost a few bucks more,
but I think worth it.

Regards,

Jeff M



> --- David Hrivnak <[email protected]> wrote:
> 
> > Jeff what trouble with you have with Dual-Pro? I
> > did have one fail but they
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] charge in parallel, discharge in series*



> --- David Hrivnak <[email protected]> wrote:
> 
> > I thank you for a clear explination. I also
> > searched the archives and saw some of the problems
> ...


----------

