Charging a battery while it's in use

Arashi

Can a battery be charging while it's in use?

For example... Say I'm running my inverter off of my battery bank to run a TV.... and at the same time, I've got a 100w panel sending current to the battery.

Will the battery be getting any charge from the solar panel?

lorelec

Re: Charging a battery while it's in use

Arashi,

If your loads require more power than your solar panel (minus wiring losses, etc.) is able to provide, then your battery won't be getting any charge -- it will be discharging. On the other hand, if you have only a 50 watt load and your panel is outputting full power, then your batteries will soak up the excess.

Marc

Arashi

Re: Charging a battery while it's in use

Thanks Marc,


What if my load is 300 watts, and the panels are putting out 100 watts. Will only 200 watts be depleted from my batteries?

BB.

Re: Charging a battery while it's in use

To clarify... Watts is a "rate"--like Miles per Hour.

Watt*Hours is energy used--like miles driven.

Say you use your TV for 3 hours at 100 watts:

100 Watts * 3 Hours = 300 watt*hours

Say your solar panels can charge in the summer for 100 watts for 5 hours (5 hours of noon-time equivalent sun strength):

100 watts * 5 hours = 500 Watt*Hours

In this example, you are 200 watt*hours ahead in charging and all is OK...

However, say you run your load at 300 watts for 4 hours per day:

300 watts * 4 hours = 1,200 watt *hours

In this example, you are 1,200-500=700Watt*Hours per day in the whole--either you will need an external charger, genset, more panels, or not use your load for almost two days to recharge the battery bank.

In reality--it is a bit more complex (sorry)--but if you know your loads (watts and hours of use per day), know your location (how much sun). We can give you a walk through of how much solar panels you would need to power your loads...

Just a warning, Off-Grid Solar power is not cheap... You may pay $0.10-$0.20 per kWhrs for power at home... An off-grid system probably would cost you $1.00 to $2.00+ per kWhr (depending on lots of things).

So, conservation (efficient appliances and turning things off you don't need, using less overall) is an important part of building a satisfactory off-grid solar PV system.

-Bill