Laptop charges off 12v battery/inverter when full, stops after a while

[tara1234]

Hey so I have a 300W inverter and a 24ah 12v battery. This works to run and charge my laptop for a couple of hours, however after a while the laptop stops charging but I can still charge my phone off the USB that the inverter comes with.

Can someone explain why this might happen, does the battery need a certain amount of AH to be able to put out power. So for example when my battery reaches say 6AH/24 it simply does not have enough to power the 300W inverter?

 

[static zap]

Is it a leisure battery , or an ordinary Car starter battery ?

 

[tara1234]

Hey im not that sure, I think it is probably deep cycle it says for industrial standard use. It is a yuusa valve regulated lead acid battery.

Update: I plugged my little netbook in which uses a much weaker supply and its charging. But doesn't work with the big laptop until I fully recharge the SLA.

Big laptop PSU
input: 100-240v 1.7a
output: 19.5v 6.15a

Small laptop
input: 100-240v 1.3a
output: 20v 2.25a

 

[static zap]

Real world results ,can be confusing . A cheap Digital Multi-meter on VOLTS
my help you understand what is going on .
( and things that will harm your battery - like discharging Too deep)
From you results , you may be on a slippery slope .
(If it turns out to be a starter/CAR battery - they are awfull at what you want !)
A decent charger is also needed to keep things healthy .
What sort of room temperature is this all happening at ?

 

[tara1234]

Its about 15-20 Celsius.

When I plug my big laptop into the inverter the charger stops working but the small laptop works fine.

Right playing with some other batteries.

a 12 ah (Fully charged) one, chargers little laptop fine, big laptop it flickers on/off with the charging.

So by this assumption does this mean that the battery needs more than 12 AH remaining to be able to charge my laptop?

 

[Specialist]

If you've only been part discharging then recharging the laptop battery over a period of time, then it's possible that the battery can no longer accept a full charge.
You could try a few full discharge / recharge cycles to recondition the battery or you may need a new laptop battery.

 

[static zap]

That sounds reasonable , In-efficiencies are your enemy .
Even the charge cycle is in-effiecient !
(I cannot be much more help without knowing voltages )
As described , battery sounds like it's struggling at higher load or weakness elesewhere.
Check you 12V wires for any warm patches , showing poor connections,
while using higher load nextime .
( Take care as I've witnessed a wire cutting into a duvet -12V- no fuses )

 

[tara1234]

Also since both batteries have some power but are not enough to deliver a charge. Would connecting them in parralel allow them to give a high enough charge to get the inverter working or is it a bad idea to have batteries of different sizes connected to each other.

Iv heard its a bad idea while charging them but what about discharging them?

 

[static zap]

Combined is bad news , especially if voltges are un-known .
( only stands a chance if near identical -type/age/health ..and even then
they drift apart )
A few seperate load tests with a voltmeter help compare health and which may need more charging . ( bye/late )

 

[SparkyChick]

Tara, I'm going to suggest something radical... how about asking your landlord if they'll get a power outlet or two installed in your room?

I find it hard to believe that it's not a requirement to have at least one outlet in each room. I'm assuming it's a house of mulitple occupation, or you're renting a room as a lodger.

 

[Specialist]

Hi SC, you may be surprised what the landlords of HMO's get away with.
Unless tenants complain to the landlord then nothing will get done, if the tenant complains then it's often bye bye & next please.
It's a vicious circle really & councils don't do much until there's a real stink created by someone or God forbid someone gets hurt.

 

[SparkyChick]

I wouldn't be surprised, I must admit I went looking for info about minimum requirements for HMOs when Tara first posted about this and the jumpstarter she was using. All I could find was minimum requirements for kitchens. Other than that, it does seem it's entirely down to the landlord, which I thought was shocking.

But, based on her first post, if I was planning on being there a year, I'd be asking the landlord if they'd do something about it, especially in this day and age when practically everyone has at least one battery operated gadget that needs regular charging.

 

[Specialist]

To be fair, the majority of landlords are pretty good & give their Tennant's decent accommodation, especially when they're expecting colleges to send students their way.
But some of the others can be really bad, some of the HMO's around Pontypridd a few years back were atrocious.

 

[Octopus]

Can we go back to basics?

Why are you trying to use this set up?

 

[HandySparks]

Can we go back to basics?
Why are you trying to use this set up?

Tara, I'm going to suggest something radical... how about asking your landlord if they'll get a power outlet or two installed in your room?

From the OP's info, I'm guessing that this is for use on a boat.

How do you plan to charge the 12V battery?