Hello,

F150 2009 Supercrew 4x4. 121k miles
Battery is less than a year old.

Trying to figure out just how long I can draw power from the battery before the truck won't start. Question has three parts.

1- How long can I run the radio safely?

2- How long can I run a computer or iPad from the power jacks safely?

3- Okay I'm pretty certain I need to run the truck engine for this. Just want to make sure I'm not going to break anything. We're going camping and my wife wants pancakes one day. Doesn't trust cooking over a fire for this. She has a 120v 1500w electric griddle and wants to plug it into the truck.
I'll run the engine, but will this cause any issues with my electrical system?

 

I would make sure you run the truck for most of that. Listening to the radio would probably be okay for a little bit but its hard on your battery to draw it down and then charge it back up. This can really shorten the life of the batter. Deep cycle batteries are designed for this but not your average auto starting battery.
Bottom line for this. Run your truck for those tasks, especially while camping. It would be a crappy end to your trip if you go to start the truck and nothing happens.

 

Too many variables to give you an accurate answer. Don't know what kind of radio you have, what condition your battery is in, etc. Ipad power draw varies highly depending on what you're doing.

You can buy battery monitors cheaply (simple ones anyway!) Get one and use it. The more sophisticated ones are wired in and will automatically disconnect your load when the battery gets low. Check with the motor home/camper trailer suppliers. They're expensive there but you can get an idea of what's available.

But probably the simplest, cheapest and most reliable thing is to just get a 2nd deep cycle battery and use it (disconnected from the truck battery). If it's not connected to the truck then it can't run down your starting battery. Recharge it when you have the truck running or when it gets low.

TIP: You can monitor your battery for free if you don't mind doing it manually. Go to HF and get one of their FREE multimeters. I keep one in my truck at all times.

That griddle is a no-no unless you want to add a large sized generator to your truck. And don't even think about trying to run that beast off of an inverter. 1500 watts means a power draw of OVER 100 amps (don't forget you're only dealing with 12 volts here and not 120!) It will suck your battery dry in a few minutes. Best bet for that is a small propane (or gas) cook stove. Heck, I keep a couple of them around for hurricanes and other power fail events anyway. The one that I use for camping has one burner and screws directly on top of the gas bottle and is only about the size of a quart oil can. But for you I'd recommend a regular fold up, two burner Coleman type stove.

 

Thanks @Joe51, very helpful.

Couple of questions:

1- What's HF? Not familiar with the term. (I'm not a true gearhead, sorry)
2- In the vein of not being a true gearhead, where can I find out more about how to set up a second battery so I can recharge it from the truck when needed?

Thanks again,
AC

 

HF = Harbor Freight (the store/catalog)

 

where can I find out more about how to set up a second battery so I can recharge it from the truck when needed?

Go look at the stuff that RV dealers and camper supply companies sell. Most of that is built in and top of the line, price wise, but have them explain what's available and how it works and you'll learn a lot.

But your battery doesn't need to be built in with an automatic charging system. Just leave the 2nd battery loose and take it out and take it where you need power, then when it gets low, charge it with a standard automotive battery charger if you have AC power available or if you're away from home and still need to use it, just connect it to your truck battery with jumper cables and run the engine enough to charge it. Keep battery caps on the terminals when you're not using it and always charge it well before storing.

Oh and go look at boat dealers where they sell electric trolling motors. They use loose batteries and recharge them exactly the same way. They can probably give you advise on the best brand of battery and how long it will last with various current draws. The battery doesn't care if it's driving a trolling motor or a camp light and boom box. All it sees is the amount of current that is being drawn. A cheap DVM (Digitial Volt Meter) with current measuring capability will come in handy for measuring that. Again see HF. They even have coupons for free ones in many magazines and newspapers.