How long will my battery pack work with a battery charger connected

[gladiator]

I have a battery pack with inverter, and I'm wondering how long it would work for with the Oxford battery Oximiser plugged in? See pics below for more info.

I'm hoping someone can give me an estimate so I can connect them up to my Fiesta battery. If its viable, I'll do it

Thank you

 

[jj4091]

Not sure it is a viable proposition as I would expect the charger to trip out.

 

[Old Salt]

Depends how much power you are pulling out of it. Plug it in and see would be a good plan. Provided the post above isn’t correct! I have no idea.

 

[jj4091]

You won't be drawing power from the battery but directly from the charger as far as I can tell so a bit of a pointless exercise having the battery there unless I am misunderstanding your plan.

 

[gladiator]

You won't be drawing power from the battery but directly from the charger as far as I can tell so a bit of a pointless exercise having the battery there unless I am misunderstanding your plan.

The battery pack is full charged and has a socket allowing me to plug the battery charger in.
It'll work but it's the calculation of how long the battery pack will last before it's charge is depleted that I'm not sure about

 

[jj4091]

How long the battery pack will last depends entiely on what you are connecting it to and what current you draw from it. I got the impression you wanted to connect it to your Fiesta battery to stop it going flat but have a charger connected to your power pack to keep that charged. Or am I mistaken and if so please give more details about how you intend to use it.

 

[gladiator]

How long the battery pack will last depends entiely on what you are connecting it to and what current you draw from it. I got the impression you wanted to connect it to your Fiesta battery to stop it going flat but have a charger connected to your power pack to keep that charged. Or am I mistaken and if so please give more details about how you intend to use it.

Just want to top the Fiesta battery up, due to the car not being used much.

If the battery pack can sustain topping up the battery before running out of charge, then that's good.

The proof will be in the pudding, so I'll put a meter across my battery, try charging it and then measure the battery voltage again

 

[cdbe]

That set up will.last about 1 hour at full output of the charger.

You'd be far better with a solar panel connected directly to the car battery via a simple change controller (standard caravan type set up). Need to check compatibility with your car battery type. Panel size tricky to work out (battery discharge rate over storage time, safe discharge voltage, output of panel in winter etc) - probably a 50w would do and cheap as chips. Disconnecting battery from car would remove any potential parasitic drain if safe to do so.

 

[Rodders53]

Is that charger (up to 30Ah batteries I've read in specs) suitable for the Fiesta battery?

600mA max at 15V output = 9 Watts so at that rate will deplete the 20Ah inverter completely in two hours. But never deplete a battery fully to zero it'll quickly be ruined.

IF the Fiesta battery is fairly well charged initially lets say it only needs 1 Watt to trickle charge... (excluding losses of battery pack -> inverter -> charger -> vehicle battery DC) then it'll do around 10 hours or 20 hours max? Probably much less in reality?

EDIT Wrong!! assuming the 20Ah is at 12V nominal times those hours by 12. (Doh!)

 

[gladiator]

Thank you cbde and Rodders53

 

[Astra99]

If all you want to do is keep a car's battery trickle charged, invest in a 25W (approx) solar panel with blocking diode. This can be left permanently connected to the car when not in use. A certain well-known auction site have them fro between £25 and £30.