SLA Battery Charger help?

[bunghole]

thanks. i might try this idea but i am still searching for a charger to see what i can find. would a 3amp lead acid battery charger be okay to charge a sealed lead acid battery?
because i found this and it seems to suit my needs:
**broken link removed**

i edited the schematic to what i actually need. (P2, R5 and S1 are removed, so the charger is only for 12v)

 

[chemelec]

thanks. i might try this idea but i am still searching for a charger to see what i can find. would a 3amp lead acid battery charger be okay to charge a sealed lead acid battery?
because i found this and it seems to suit my needs:
**broken link removed**

i edited the schematic to what i actually need. (P2, R5 and S1 are removed, so the charger is only for 12v)

As it says on the Schematic, This charger is "Not for use on Gell Cells".
** I am quite sure it is also Not good for use on Sealed Lead Acid batterys for the same reason.
That Extra High Current can cause problems in these batterys, resulting in premature battery failure.

 

[mvs sarma]

Try this site and he has a good document to speak and detailed circuitry towards the end of the downloadable pdf file.

http://www.geocities.com/vk3em/sla-charger/sla-charger.html

 

[bunghole]

i could use an lm350k, which is 3amps (battery rated at 5.4)

 

[chemelec]

i could use an lm350k, which is 3amps (battery rated at 5.4)

As I told you before: Typical charging current is around 1/10 Capacity.
"So for a 5.4 A/H battery, your charge rate should be about 540 mA".

Charging at 3 amps will distroy the battery.

 

[bunghole]

sorry about that part...i forgot to say that that battery is 18Ah and has a 5.4 amp max charging current

 

[mvs sarma]

As I told you before: Typical charging current is around 1/10 Capacity.
"So for a 5.4 A/H battery, your charge rate should be about 540 mA".

Charging at 3 amps will destroy the battery.

I feel that the SLA batteries can't be frequently charged at a rate more than prescribed. Generally we may have to follow manufacturers recommendations as regards charging rate, let it be 10, 16 or 20 hr rate. Perhaps due to urgency we may charge at higher rare but such attempts must be minimal for better life of the battery.

 

[bunghole]

what current is suitable for a 20hr charge rate? (now i know what the '20HR' means)

 

[mvs sarma]

what current is suitable for a 20hr charge rate? (now i know what the '20HR' means)

I meant charging at a current =AH capacity/20 as 20hour rate. However, please study the instructions contained on the battery regarding normal and fast charge rates and let us follow them, as the manufacturer knows better about its products.I feel charging current need not exceed AH capacity/16 or AH/20. for best possible life of the battery.

 

[bunghole]

here is where i bought it:

**broken link removed**

it was on special to.
the picture is the best i could get from my camera.

 

[adnan_m_s]

minimum Charge current

Hi Guys ,
what about the minmum charge current you all siad that it is between 1/10 to 1/20HR to charge a battery is there a minimum current or if the current goes down these values the charge will only take more time ,
by the way a couple of two days ago my car battery went dead it is 50AH and I recharged it with a two amperes regulated power at 14 V i put it for approximately 1 hour and twinty minuets I installed the battery in the car and guess what? everything was OK , I used a typical LM 338 IC cercuit not a charger circuit just a regulated 14 V 2A current! by the way my battery was of the sealed kind with a little green ligh power indicator so what do you think?

 

[mvs sarma]

Hi Guys ,
what about the minmum charge current you all siad that it is between 1/10 to 1/20HR to charge a battery is there a minimum current or if the current goes down these values the charge will only take more time ,
by the way a couple of two days ago my car battery went dead it is 50AH and I recharged it with a two amperes regulated power at 14 V i put it for approximately 1 hour and twinty minuets I installed the battery in the car and guess what? everything was OK , I used a typical LM 338 IC cercuit not a charger circuit just a regulated 14 V 2A current! by the way my battery was of the sealed kind with a little green ligh power indicator so what do you think?

Fine Sir,
it doesn't mean that you have charged the battery fully? a partially charged battery also can start the car and the battery will then on get charging current from the car's charging system.

Also, we don't generally speak personal ideas while discussing and suggesting methods. Afterall for the other person seeking advise, it cost damages of equipment due to hasty or fastening advises.

these are accepted procedures. If some one made a charger that would charge a battery with in 2 hours completely, use it gladly ,but be ready for early replacement of battery.

You can't generalize that industry supplied items are all confirming to the LA or SLA or GEL battery charging standards.

 

[mvs sarma]

here is where i bought it:

**broken link removed**

it was on special to.
the picture is the best i could get from my camera.

Attached a datasheet for further analysis.

 

[chemelec]

Hi Guys ,
what about the minmum charge current you all siad that it is between 1/10 to 1/20HR to charge a battery is there a minimum current or if the current goes down these values the charge will only take more time ,
by the way a couple of two days ago my car battery went dead it is 50AH and I recharged it with a two amperes regulated power at 14 V i put it for approximately 1 hour and twinty minuets I installed the battery in the car and guess what? everything was OK , I used a typical LM 338 IC cercuit not a charger circuit just a regulated 14 V 2A current! by the way my battery was of the sealed kind with a little green ligh power indicator so what do you think?

A Normal Maximum Charge rate is1/10 Capacity.
There is No Miminum charge rate.

As to your 2 amps on that car battery, All it did was create, what they call a "Surface Charge".
Enough current to start the car (if it Starts Quickly) But Not propery Charged.

 

[ziyad]

hello everyone, im new here, and desperately want to get it right!
i'm making a charger for a 2.3A SLA battery, and so far, i found a decent schem. for a constant voltage charger. it charges at 650mAh, and thats a bit over the 1/10C rating!
i would idealy need 230mAh. i cannot use a transformer smaller than 2A, as this is part of a circuit that operates a credit card machine, and the battery will be used as a backup only during a power failure. could i add a constant current circuit to this, or just add a series resistor?
if so, what value?
Thanks in advance

 

[chemelec]

hello everyone, im new here, and desperately want to get it right!
i'm making a charger for a 2.3A SLA battery, and so far, i found a decent schem. for a constant voltage charger. it charges at 650mAh, and thats a bit over the 1/10C rating!
i would idealy need 230mAh. i cannot use a transformer smaller than 2A, as this is part of a circuit that operates a credit card machine, and the battery will be used as a backup only during a power failure. could i add a constant current circuit to this, or just add a series resistor?
if so, what value?
Thanks in advance

Why not just use my circuit?

Its also a constant Voltage charge with a Current limit that you can easily set to 230 mA.

**broken link removed**

Even though this shows a Center Tapped transformer, a regular transformer and a full wave bridge is quite acceptable.

Your 2 amp transformer is Probably OK, But you didn't say at what voltage it is?

 

[mneary]

uhhh, SLA needs a constant voltage for a float charge. 1/10C will boil it away in a few weeks.

 

[chemelec]

uhhh, SLA needs a constant voltage for a float charge. 1/10C will boil it away in a few weeks.

You obviously didn't look at my charger.

It is Both Voltage and current Regulated.
And it Definately won't boil it away if set up properly.

Set it to 13.6 volts for a continuous Float charge,
Or 14.6 volts for a normal re-charge operation.

 

[mneary]

I responded to ziyad's post.

Sorry for the confusion.

 

[ziyad]

Why not just use my circuit?

Its also a constant Voltage charge with a Current limit that you can easily set to 230 mA.

**broken link removed**

Even though this shows a Center Tapped transformer, a regular transformer and a full wave bridge is quite acceptable.

Your 2 amp transformer is Probably OK, But you didn't say at what voltage it is?

Thanks for the quick response, as for my transformer, its rated 12V at 2 amps, but if with no load, or slight load, reads over 15V. ir it doesnt work, i will change it, but that part is not so serious.
From what i have read on this forum, i think, a SLA (12V) can be charged continuously at 13.6V without causing damage, coz the current drops to near zero at full charge.
If i go with your charger, can it be connected permanently to the battery, and also, can the battery be connected to the charger without any power on the input of the circuit, (like a power failure)?
one more thing, (i hope ), can i stack voltage regs in parallel to increase current handling?