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Solid state charger

I

Inovation

Jan 1, 1970
0
Hi, I am working on a project using a solid state charger to charge a
battery, but it breaks down
with the battery load and won't put out. It works fine off the
battery. This is a 12v system and the chargers are 1amp chargers. I
have one type that works, but a couple of different ones that won't.
Do I need a load resistor to fool the charging circuit? The batteries
are only pulled down to 7.2 volts, but they won't work on a new
battery either. What do I need to do?
Thank you,
TC
 
T

Tam/WB2TT

Jan 1, 1970
0
Inovation said:
Hi, I am working on a project using a solid state charger to charge a
battery, but it breaks down
with the battery load and won't put out. It works fine off the
battery. This is a 12v system and the chargers are 1amp chargers. I
have one type that works, but a couple of different ones that won't.
Do I need a load resistor to fool the charging circuit? The batteries
are only pulled down to 7.2 volts, but they won't work on a new
battery either. What do I need to do?
Thank you,
TC
What type of batteries? Are the chargers meant for charging these?

Tam
 
E

EdV

Jan 1, 1970
0
Hi, I am working on a project using a solid state charger to charge a
battery, but it breaks down
with the battery load and won't put out. It works fine off the
battery. This is a 12v system and the chargers are 1amp chargers. I
have one type that works, but a couple of different ones that won't.
Do I need a load resistor to fool the charging circuit? The batteries
are only pulled down to 7.2 volts, but they won't work on a new
battery either. What do I need to do?
Thank you,
TC

Some battery chargers "fold back" when they source too high a
current. Weird that the charger doesn't charge a new battery. Are
you sure the new batteries aren't dead?

Send more info on batteries and chargers.
 
I

Inovation

Jan 1, 1970
0
Some battery chargers "fold back" when they source too high a
current. Weird that the charger doesn't charge a new battery. Are
you sure the new batteries aren't dead?

Send more info on batteries and chargers.

Yes, these are new batteries. They are Rechargable sealed lead-Acid
18Ah batteries. One of the chargers is a DVE switching adapter Model
DSA 30w Output 12v 2amp. Thanks
 
I

Inovation

Jan 1, 1970
0
Some battery chargers "fold back" when they source too high a
current. Weird that the charger doesn't charge a new battery. Are
you sure the new batteries aren't dead?

Send more info on batteries and chargers.

Can I externally use a resistor to keep the charger from " folding
back?"
 
R

Roger Hamlett

Jan 1, 1970
0
Inovation said:
Yes, these are new batteries. They are Rechargable sealed lead-Acid
18Ah batteries. One of the chargers is a DVE switching adapter Model
DSA 30w Output 12v 2amp. Thanks
First problem. The charging voltage for a 12v lead acid cell, needs to be
well above 12v. It'll depend on the actual cell structure of the battery,
but typically 13.8v. A 12v supply, will _not_ charge a '12v' battery.
Second problem. Your batteries are hellishly over discharged, if they are
'pulled down to 7.2v'. Normally discharge should not go below about 10v,
or you risk destroying the cells.
You need a voltage regulated supply, able to deliver 13.8v (check with the
battery manufacturer for the right figure), which is then current limited
to deliver the required charging current. Ideally, the system should have
a two stage voltage level, turning up the voltage if the cell is bdly
discharged, and then turing it down when the battery approaches full
charge (to avoid overcharging the battery). Several manufacturers do
control IC's designed to implement such a charger, but you are looking at
something _much_ more complex than what it sounds like you have...

Best Wishes
 
T

Tam/WB2TT

Jan 1, 1970
0
Inovation said:
Can I externally use a resistor to keep the charger from " folding
back?"
Try a 10 Ohm 10 W resistor in series with the charger. That should prevent
foldback. The charger should be putting out at least 14 V on its end. If
the battery is down to 7.2V, its gone, like somebody said.

Tam
 
R

Robert Adsett

Jan 1, 1970
0
Roger Hamlett said:
First problem. The charging voltage for a 12v lead acid cell, needs to be
well above 12v. It'll depend on the actual cell structure of the battery,
but typically 13.8v. A 12v supply, will _not_ charge a '12v' battery.
Second problem.

True but the OP did say it was a 12V charger (not PS) and as long as
it's meant for lead acid and not some other chemistry then a 12V charger
will provide an appropriate output voltage. However sealed lead acids
require slightly different charging than flooded.
Your batteries are hellishly over discharged, if they are
'pulled down to 7.2v'.

Now there's a possible problem. A good charger will refuse to start if
the battery voltage is too low. Amoung other things to keep from
charging a 6V battery with a 12V charger and 7.2V sounds more like a 6V
battery than a 12V battery.

Robert
 
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