Maker Pro
Maker Pro

what amperage

Defib

Nov 15, 2010
3
Joined
Nov 15, 2010
Messages
3
Hello

I am designing a basic portable power pack and I am planning on using a 12v SLA with 7Ah rating.

Basically it will, when required, need to have a cigarette charger for a cell phone plugged into it and other basic items.

What draw will the cigarette lighter charger for my phone have??

Is my selection of SLA correct??

Will it drive a 12v to 240v Waeco 150w invertor??

Please assist, I'm not tooo clued
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
Messages
25,510
The current it draws will depend on the phone. You can measure this easily if you have a multimeter. The 7Ah SLA seems entirely adequate for this.

It would drive that inverter at full power for approximately 20 minutes.
 

Defib

Nov 15, 2010
3
Joined
Nov 15, 2010
Messages
3
Thanks for your reply

So if I use the SLA with say an inline fuse and the car cigarette charger it would be ok???
 

barathbushan

Sep 26, 2009
223
Joined
Sep 26, 2009
Messages
223
There is no doubt , that a phone can be charged with your sla battery , since it consumes around 5 to 8 watts , depending on your style of charger , if you use a switched mode charger , you will get higher efficiency than a linear charger

but i wouldn't connect a 150 watt load , at 12 volts full power , the current drawn is about 12 to 13 amps , which is too high a discharge rate for a 7ah battey .which results in sulfation and shortens the battery life .
Like steve said the battery will last 20 minutes , but steve should have known that sla
batteries are not designed to discharge to less than 20 % of the capacity , as sla batteries are not regular "Cyclic" batteries .

but you can overcome this problem by connecting two same 7ah batteries in parallel , thereby increasing the capacity of the battery to 14 AH at 14 volts , then you can use your inverter to about 45 minutes
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
Messages
25,510
but i wouldn't connect a 150 watt load , at 12 volts full power , the current drawn is about 12 to 13 amps , which is too high a discharge rate for a 7ah battey .which results in sulfation and shortens the battery life .
Like steve said the battery will last 20 minutes , but steve should have known that sla
batteries are not designed to discharge to less than 20 % of the capacity , as sla batteries are not regular "Cyclic" batteries

I'm not sure that I agree with your assumptions about what I should and shouldn't know.
 
Top