help my verify my charging (in)sanity

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help my verify my charging (in)sanity

jonglauser
I've been confused about my charging recently.
I have a 96V pack of 14 month old golf car batteries.
I have an emeter to monitor them.
I have a Russco SC30-120 SO to charge them. 2-3 stage charger? not
sure, it's old and I dont have the manual in front of me.

They should have a 100% charge voltage of 101-102V. They usually sit
at 99-101V in the morning after a charge.

at 80F I should charge them to 115V
at 35F I should charge them to 121V

I've noticed that regardless of the temperature I cant get them above 113-115V.
I have set the current to maximum, which pushes 10-13A into the
batteries. It will do that all night and they boil away. Voltage never
gets much more than 113-115. The charger doesnt trip to finish charge.
I thought I had the voltage set too high on the charger and so turned
it down.
I can get the charger to run its normal stages: charge to set voltage
then less voltage (or just less current? The voltage drops) for a set
time (I think I have it at 1 hour). But only if I reduce the set
voltage.

The other day I set the current limit very low and it pushed some 2A
into the batteries all night. The charger never went to final timed
mode, but they batteries were very responsive the next day!

Am I charging wrong? Is my charger not working? Are my batteries
dying? any help please




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

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Re: help my verify my charging (in)sanity

damon henry

If you have been driving with them very cold, and you noticed they were much more responsive after the 2A overnight charge, it could just be that you heated them up that way, so they were performing like summer instead of winter :-)

 

damon

>
> The other day I set the current limit very low and it pushed some 2A
> into the batteries all night. The charger never went to final timed
> mode, but they batteries were very responsive the next day!
>
> Am I charging wrong? Is my charger not working? Are my batteries
> dying? any help please
>
>
>
>
> -Jon Glauser
> http://jonglauser.blogspot.com
> http://www.evalbum.com/555
>
> _______________________________________________
> General support: http://evdl.org/help/
> Unsubscribe: http://www.evdl.org/help/index.html#usub
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archive / Forum: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>

     
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Re: help my verify my charging (in)sanity

Roland Wiench
In reply to this post by jonglauser
Hello Jon,

You did not say what type of battery you have.  Lets say it's a Trojan
battery, then the normal charge or sometimes call the absorption charge is
7.4 volts at 80F at which is the maximum set point voltage where it should
hold this voltage while the current decreases.

If it's a U.S. Battery the bulk stage is 7.2 volts and absorption charge is
at 7.75 volts at a decrease ampere which can be set at these voltages in a
three stage charger.

If a constant current charger is use that has no bulk stage, then you may
have to lower the absorption charge point so the current is reduce after the
battery reaches 7.2 volts, but the voltage still increases to the acceptance
voltage.

Sounds like you are only charging up to 7.2 volt stage which is call the
bulk charge stage.  At 7.2 volts the charger is at maximum ampere and then
it should go to the next stage which would be either to 7.4 volts for a
Trojan battery or 7.75 volts for a U.S. Battery.

In some chargers, the current is reduce between the bulk stage and the
absorption stage.

I am using a PFC-50 charger which does not have a bulk stage, so it is full
maximum ampere up to the absorption stage, so depending on the age and type
of battery, I may lower the absorption voltage so my current starts to drop
off sooner.

It looks like you stop the charge at about the 7.2 volts per battery or 7.2
x 16 = 115.2 volts.  You should at least be going to 7.4 volts for a Trojan
which is 118.4 volts and for a U.S. Battery is 124 volts.

If your battery is discharge between 50% to 85% SOC, then it is recommended
to charge at a C/10 rating or the ampere-hour of the battery / 10.  If you
have a 200 AH battery than the charge current should be 20 amps.  A 250 Ah
battery will be 25 amps.

In a three stage charger the current should then decrease after you reach
7.2 volts, the voltage should increase in the next stage which is the
absorption stage which is between 85% to 100% SOC, then the current
decreases and then go into a float stage.

When the ampere drops to about C/50  or in a 200 Ah battery this would be
200/50 = 4 amps.  The battery is consider 99-100% charge.

If I charge my 250 Ah battery at 5 amps, even though it is about 98% SOC, it
will never get to the absorption voltage in a reasonable time,  I have to
set it to at least 15 amps to get it there which only takes about 5 seconds,
then it only takes another 5 minutes for the current to drop below 5
amperes.

The battery voltage after setting 24 hours should read between 6.37 to 6.4
volts at a specific gravity reading of 1.277 sg per cell.

Roland






----- Original Message -----
From: "Jon Glauser" <[hidden email]>
To: "Electric Vehicle Discussion List" <[hidden email]>
Sent: Wednesday, December 23, 2009 11:43 AM
Subject: [EVDL] help my verify my charging (in)sanity


> I've been confused about my charging recently.
> I have a 96V pack of 14 month old golf car batteries.
> I have an emeter to monitor them.
> I have a Russco SC30-120 SO to charge them. 2-3 stage charger? not
> sure, it's old and I dont have the manual in front of me.
>
> They should have a 100% charge voltage of 101-102V. They usually sit
> at 99-101V in the morning after a charge.
>
> at 80F I should charge them to 115V
> at 35F I should charge them to 121V
>
> I've noticed that regardless of the temperature I cant get them above
> 113-115V.
> I have set the current to maximum, which pushes 10-13A into the
> batteries. It will do that all night and they boil away. Voltage never
> gets much more than 113-115. The charger doesnt trip to finish charge.
> I thought I had the voltage set too high on the charger and so turned
> it down.
> I can get the charger to run its normal stages: charge to set voltage
> then less voltage (or just less current? The voltage drops) for a set
> time (I think I have it at 1 hour). But only if I reduce the set
> voltage.
>
> The other day I set the current limit very low and it pushed some 2A
> into the batteries all night. The charger never went to final timed
> mode, but they batteries were very responsive the next day!
>
> Am I charging wrong? Is my charger not working? Are my batteries
> dying? any help please
>
>
>
>
> -Jon Glauser
> http://jonglauser.blogspot.com
> http://www.evalbum.com/555
>
> _______________________________________________
> General support: http://evdl.org/help/
> Unsubscribe: http://www.evdl.org/help/index.html#usub
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archive / Forum: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>

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