Help with AMPS and recharge times (1 Viewer)

[Fisher23]

Is my math right?

I have a single battery running this fuel pump for refilling fuel tanks.

The pump transfers 15 gallons per minutes so I run the 4 or 5 minutes to refuel the 60 gallon tank.

The max amps the pump draws is 30 amps (on the fuse).

So if I have a solar 5 watt battery charger that get 8 hours of perfect sun light, how many days would it take to recharge the 15 drain on the battery?

Is it (30 amps x 1 minutes) = 7.5 amp hours
The 7.5 watts charge / 12 volts = 0.625 amp hours
Then 7.5 amps / 0.625 = 12 hours of sun light hours to re-charge .. or 2 days to charge back up given not running at 100%

Did I do that right? 2 days to recharge the 15 minutes.


This is the pump

12V DC 15 GPM Fuel Transfer Pump with Nozzle

Fill-Rite's 1200 Series of heavy-duty fuel transfer pumps feature simple installation with a rotatable junction box and are built to last with cast-iron construction.

www.fillrite.com

I was thinking of using this charger

https://www.etrailer.com/Battery-Charger/Bright-Way/BRW54FR.html

 

[e9999]

the pump won't draw 30A, and your panel will not give you 5W (geez, that is low) the majority of the time. So lots of uncertainty there.
I'd go:
20A (guess) x 12.5V = 250W
If you use it for 5 minutes, you got 1,250Wm = 20.8 Wh
If your 5W panel gives you 2W on average (not too likely with this kind of cheapo charger, I would think), it would take 10hrs or so of good sunshine to recharge.
So, yes, a day or 2.


(this thread would best be in the Power Systems forum)

 

[Fisher23]

Thanks !

 

[e9999]

if it were me, I'd get a cheap small PWM controller and a bit bigger panel, like 20W. This would be much more versatile for future uses and would get lots more power, with probably little more cost if any. A separate 20W panel would be about $40 and an inexpensive controller about $20. A bit of connection work but easy. And at least you know what you have, unlike the generic system you showed, which is unlikely to have a real controller.

 

[Fisher23]

if it were me, I'd get a cheap small PWM controller and a bit bigger panel, like 20W. This would be much more versatile for future uses and would get lots more power, with probably little more cost if any. A separate 20W panel would be about $40 and an inexpensive controller about $20. A bit of connection work but easy. And at least you know what you have, unlike the generic system you showed, which is unlikely to have a real controller.

Like this one?

Amazon product ASIN B07NPDWZJ7

 

[e9999]

yes, like that. PWMs aren't the best but likely good enough for your application, especially if the panel is a bit bigger than strictly necessary.
When you buy a controller think about what you may want to use it for later, though, as its rating (max amp and panel voltage) may limit you in the future and you can't change that. I for one would usually get a bigger than needed controller just cuz I know I will likely want mo' powa' eventually anyway. This one for instance you likely could not put more than 125W or so on with a 12V battery. You also want to check that it supports the specific types of battery you want to charge (FLA, AGM, Li etc).

 

[Fisher23]

Thanks again