Looking for input on an idea...

[Thatoneguy]

Ok so I'm currently in the process of gathering material for a custom built truck bed tool box... It will have a removable tool tray with foam cutouts for each socket, wrench, etc., LED lights for the bed, AND a power inverter neatly hidden away with probably 2 110V plugs going under the arm of the tool box that goes over the bed rails. I chose that location so that they will be concealed and protected from the elements. Now, onto the question... For the inverter I'm not sure how to run the electrical. I could install a battery isolator and separate the two batteries. One would be a deep cycle battery for powering tools and such while the truck isn't running, and the other would probably have to be a really nice sized battery to be able to start up the truck alone.... Or, I could fabricate a battery tray for the passenger side of the engine bay where the two stock batteries would sit next to each other and retain their stock functions with a separate battery on the drivers side which would be the deep cycle for the inverter and also hooked up to the alternator so it can be charged up. Does anyone know how many amps a battery would need to start these trucks alone? Any thought or ideas would be appreciated!

 

[OLDBULL8]

That is a loaded question about batteries. All batteries are rated in Amp Hrs A-H. Lead acid batteries should not be discharged below 20% of there capacity, re-charging below that % causes heat, that reduces the life.

As far as using an Inverter to provide 120 VAC, you will find even the largest Automotive battery won't provide use for very long, example is an 8D battery which is very large. Six volt Golf cart batteries hooked in series will provide longer usage life when used with an Inverter. They have larger plates and can stand quicker recharging.

All of the above is contingent on what power tools Amp draw your using.

To start a Diesel, our size, depending on a lot of parameters, usually takes 500 to 800 Amps draw to get the engine to start to turn over, once the engine is turning over, the Amperage drops considerably (300 to 400).
Parameters would be, Ambient Temp, Compression PSI, Oil Viscosity, Starter Itself, Cable size and condition, Battery condition, Etc.

Recharging batteries usually takes ( using a 15 Amp charger) six times as long to charge as opposed to how long a period the discharge was.

The colder the Ambient temp is, the battery efficiency reduces.

 

[Plowmaster]

I think I would be more apt to try and engineer a generator to run off a tranny pto.

 

[Thatoneguy]

So what about using an inverter just to charge batteries? I use a lot of cordless tools and the batteries for them these days don't take long to charge at all. I would probably end up being better off installing a third battery? And for the generator. @Thewespaul mentioned a small diesel generator that is fed from the trucks fuel tank...

 

[madpogue]

Charging cordless tools won't require an isolator; it's not enough draw to worry about.

For your 18-20V tools, get a cordless charger that is powered by 12VDC. Whatever brand you use, there should be one available. I have one for my Ryobi ONE 18V batteries.

If you're running 40V or 56V cordless, I reckon you'll need an inverter. But it's pretty low current. My Ryobi 40V charger draws something like 80W, so even a small inverter will do.

I've charged multiple 18V batteries, multiple 40V batteries, a cell phone and a DSLR camera battery, all off the power/lighter socket in the cab, even without starting the truck for several days. At spring/summer temperatures, I still have plenty of reserve to start the truck.

 

[compressionignitionrules]

I like your idea of using the stock starting battery on one custom battery tray then using your isolated battery on the other side in a stock tray. 2 65 series 875 cranking amp batteries come stock. thats a lot of cranking if you want to switch to single battery.

why not just put a solar panel charger on top of your tool box and keep your tool charging battery under or in the toolbox. I got 2 coleman 40 watt solar panels with 7amp charge controllers for $150 , I use one for the sheep fence with a 31S battery (non deep cycle) they are cheap batteries with so many companies selling them, can find a sale for under $80 occasionally.

you wouldn't even need an isolator . totally standalone.

hey its an idea?

 

[Thatoneguy]

Ya I know cordless tools wouldn't really NEED an inverter, but I like the idea of having one in case I ever actually did need to power a corded tool even for just a min... I know I wouldn't be able to power them all day long or anything. I do like the idea of solar panels... I'm just wondering if I were to go solar, would I still be able to use a nice and big deep cell battery for a bit more juice? I know it would take forever to charge it on solar but I'm not gonna be using it every day either. So it would have plenty of charging time in between uses.

 

[Longwolf]

I set my old 6.9 van up with three of the largest marine batteries that Walmart offered , a 150 watt solar panel and a 750 watt inverter. There was no battery isolator and i never had a problem. I removed the old standard batteries completely.

If your only charging tool batteries and you drive your truck regularly, you probably don't need the solar panel.
My research on lead acid batteries was 10% draw for standard, 25% for marine and 50% for true deep cycle batteries. But most of the deep cycle batteries are 6 volts, so you have to buy them in pairs. And they're expensive.

 

[Macrobb]

I'd probably just use two group 31 batteries - one cranking, one deep cycle.
Set the deep cycle on the driver's side, cranking on the passenger's side.
Install a physical connect/disconnect on the positive side between the two batteries, and a battery isolator(diode type) between the alternator and each of the batteries.

Now, you normally leave the physical disconnect open, you use the passenger's side battery /only/ for cranking, and the driver's side is a spare. In a pinch, you can connect the two and have more capacity available for cranking - the deep cycle battery has more total capacity, but less amps available, the cranking battery is the opposite.

Inverter gets hooked to the driver's side battery, and I'd probably mount it in the engine compartment if possible - the closer it is, the less loss and expensive heavy copper cables.

Now, if you *do* need a bunch of current out of it, more than just a work light or tool charger... fire the truck up. Same if the deep cycle gets low. The alternator(assuming 3g) will put out a /lot/ of current trying to maintain that 14.5V or so; the driver's side battery will be pulled down by the load and the current will end up 'going to' that battery to keep it charged, without overcharging the starting battery - at least, any more than usual.

 

[DaveBen]

I'd probably just use two group 31 batteries - one cranking, one deep cycle.
Set the deep cycle on the driver's side, cranking on the passenger's side.
Install a physical connect/disconnect on the positive side between the two batteries, and a battery isolator(diode type) between the alternator and each of the batteries.

Now, you normally leave the physical disconnect open, you use the passenger's side battery /only/ for cranking, and the driver's side is a spare. In a pinch, you can connect the two and have more capacity available for cranking - the deep cycle battery has more total capacity, but less amps available, the cranking battery is the opposite.

Inverter gets hooked to the driver's side battery, and I'd probably mount it in the engine compartment if possible - the closer it is, the less loss and expensive heavy copper cables.

Now, if you *do* need a bunch of current out of it, more than just a work light or tool charger... fire the truck up. Same if the deep cycle gets low. The alternator(assuming 3g) will put out a /lot/ of current trying to maintain that 14.5V or so; the driver's side battery will be pulled down by the load and the current will end up 'going to' that battery to keep it charged, without overcharging the starting battery - at least, any more than usual.

I have a couple of questions on this approach; Way are you dividing the batteries in two? Why are you trying to isolate each battery/charging system? You, originally, have one battery in two places and the main reason is to power the starter and glow plugs. I can see isolating a third battery for your inverter. I think you will be killing each battery sooner by your method.

 

[Thatoneguy]

I would assume he wants to separate them so that when the truck is not running, you aren't draining your cranking battery. Running a crank battery dead or even very low is extremely harmful to the battery itself. That's what deep cycle batteries are made for.

 

[Thatoneguy]

So if I'm tracking on what everyone is saying... My options are:
A. Small generator installed probably in a small section of the tool box.
B. Solar panel with a battery or two dedicated for the powering of accessories completely separate from the trucks charging system.
C. Install a third and massive deep cycle battery (possibly two) separate from the two already in the truck. These would be wired to be charged by the alternator (currently a 3G) but not tied into the stock batteries at all.
D. Separate the two batteries. Install a very beefy cranking battery on the passenger side, and another beefy battery except this one a deep cycle on the drivers side. Deep cycle to power accessories, cranking to fire up truck. With the option of connecting the two in the event of an emergency.

I think I got it all but please correct me if I'm wrong. I do like the idea of putting both stock batteries on the passenger side, or even eliminating one of them for one large cranking battery. I don't particularly care for the generator idea, because then I'm taking space out of the inside of the tool box and have to worry about exhaust and airflow so it doesn't overheat...

 

[riotwarrior]

Work boxes like this exist already and are $pendy.

An AGM 8D or two should be good for inverter..build frame mounts and voila!

Inverter should not be under hood...way to hot IMHO as it will be exposed to an environment not condusive to long life or efficiency.

Ever see an ambulance and how the inverter n electrical are set up..diedicated compartment away from excess heat.

JM7.3CW Eh!

 

[madpogue]

^^^^ +1; plus, wrt. wiring, there's no free lunch. If you put the inverter forward, then the wiring going back to the outlets in the bed will have to be larger to accomodate the current over the longer distance. If anything, I'd move the dedicated battery AND the inverter back. That way, the wiring from battery to inverter and inverter to outlets are all short, and the only long wires are alternator to third battery. Charge current to that battery should be less than load current battery-to-inverter or inverter-to-outlets.

 

[Thatoneguy]

Very valid points. I never was planning to have the inverter itself under the hood. I got some noodeling to do. And ya boxes like this do exist... But I'm a welder. So I get to build it myself stronger, and how I want it!