Hi,
I have recently purchased a 12 volt lead acid battery.
I have linked a photo below
I am going to be using it to power 3x 12 Volt fans that only draw 0.15ma
I was wondering what voltage I would have to charge it at (I wan't to be realy sure I don't damage the battery so maby leave some room in there)
Also can I charge it with a lab bench power supply my model can output 30 Volts At 3 Amps (It doesn't have to charge quickly I just want to preserve it
If so what do I charge it with
I have seen people using a multi meter to monitor the voltage when charging
Thanks Robbie

 

hi Mc7,
It is a SLA [Sealed lead acid] battery.
Do not discharge below 10.8v , preferably 11v.
Recharge at 13.8v
You should use a SLA charger.
E

 

Thanks for your reply
It is a SLA battery
So I can't use my lab bench power supply

 

If I cannot witch one would I use
https://www.jaycar.com.au/6-12v-fully-automatic-lead-acid-battery-charger-800ma/p/MB3519
https://www.jaycar.com.au/12v-1a-sla-battery-charger/p/MB3619

 

hi,
You could use your bench power supply, ensure the voltage output is set to 13.8V
I use my PSU to charge SLA, set at 13.8v.


E

 

hi,
You could use your bench power supply, ensure the voltage output is set to 13.8V
I use my PSU to charge SLA, set at 13.8v.


E

Sory im new to this so I don't need to set it at a certain amperage

 

hi,
No, the battery will only draw the current it needs to recharge.
It will start at approx 0.5 Amp falling to approx 0.1A as it charges.
If your PSU has a current meter you could monitor the current and voltage as it charges, that will give you an idea of the condition of the battery.
Lets know what you measure.


E

 

Hello,

Looking at the picture, the recommended charging voltage is 13.5 Volts:



Set a Bench power supply to 13.5 Volts.
Add a resistor of 10 Ohms in series to reduce the starting charging current for protection.

Bertus

 

Ok so something like this (I know best drawing in the world )
stop using battery at 11 volts then charge it
So start charging at 13.5 Volts and limit it a 600 Mili Amps
It will draw 0.5 Amps and slowly drop
Is this it, when it is done it will draw 0.1 Amps ???

 

Hello,

I said a 10 Ohms resistor, you have drawn a 10K resistor in your schematic.

Bertus

 

Hi,
Ops sorry is this better
So that should pretty much work
If I do what I described above

 

So this one
https://www.jaycar.com.au/10-ohm-10-watt-wire-wound-resistor/p/RR3352

 

hi,
Try it with the resistor and without the resistor, post your measurements
E

 

I can't do it now but I can do it next week
I don't have access to my power supply before then
Do I really need the resistor

 

Hi,
What I will do is be using it to drive 3 Fans
I will monitor the voltage with a display and when it gets down to 11
Turn it off and then hook it up to my power supply voltage limit it a 13.5 Volts and Limit it at 600 Milli Amps
Then when the amp display shows it only drawing 0.1 Amp turn it off
Then I can use it again

That is basically all I will be using it for

 

Hello,

On the battery is given "initial current less than 0.39 A"
When the battery is 11 Volts and the power supply is 13.5 Volts, the 10 Ohm resistor will set an initial current of 0.25 A.

Bertus

 

hi,
With any project powered from a SLA or high capacity battery, I would use a fuse in the +12V line to the load [your fans]
A 1 amp fuse would be OK.
E

 

Ohh I get it now

So this

What I will do is be using it to drive 3 Fans with inline fuse
I will monitor the voltage with a display and when it gets down to 11
Turn it off and then hook it up to my power supply and hook up resistor in series voltage limit it a 13.5 Volts and Limit it at 600 Milli Amps
Then when the amp display shows it only drawing 0.1 Amp turn it off
Then I can use it again

Can I use this resistor
https://www.jaycar.com.au/10-ohm-10-watt-wire-wound-resistor/p/RR3352

 

And this fuse
https://www.jaycar.com.au/1a-3ag-quick-blow-fuse/p/SF2190

 

That fuse is OK, do you have a fuse holder for it.?