Just wondering...

[bigtruck94]

I have been bored today and I have been thinking about some ideas of having a second battery. Now I don't want to do any kind of big wiring or installing a big isolater. I just want to have a battery and add all my wiring from my lights and all sorts. I plan on putting the battery underneath my toolbox and welding a box around it to protect it. What do you think? Is there some kind of special terminals I need to use? Some advice would be appreciated.

Thanks

 

[Lil-Pony]

So a battery set up like a diesel? Just with the battery below your tool box?
Take a look at ruff stuffs battery boxes

 

[bigtruck94]

So a battery set up like a diesel? Just with the battery below your tool box?
Take a look at ruff stuffs battery boxes

Well kind of. It's not the box I am really looking at. I am thinking of just adding a big metal box underneath the toolbox and protecting the battery from water or anything that will destroy it.

 

[Lil-Pony]

Why not in the tool box, I'm going to relocate both my overflow and wiper fluid to mount a box behind my driver lamp or figure out how to have them side by side on the existing mount.

 

[Lil-Pony]

Point is I don't see a problem. Recommend 4awg to connect the two together

 

[lil_Blue_Ford]

You need an isolator. Period. It's been discussed MANY times. If you hook the batteries up incorrectly, you'll put 24 volts to the harness instead of 12 which your truck will NOT like.

If you hook up a battery just to power lights and not be connected into the charging circuit, when it goes dead, it's dead. A lot of lights will drain a battery faster.

When you fire up your truck and turn the lights on, the alternator takes the load. If you have too much draw on the charging circuit and the alternator is too small to handle it, you'll draw the remainder off the battery.... which means the battery will run down even though the vehicle is running.

If you're having charging issues, it's time to upgrade your alternator, not add another drain to the system. Adding a second battery will only make the problem worse because if the alternator is not keeping up charging one battery and powering everything, adding another battery is only another drain on an already overstretched system.

If the charging system is keeping up, you can add another battery with an isolator. The isolator allows the alternator to charge just one battery at a time. That way the alternator isn't struggling to charge two batteries plus power everything.

IIRC, isolators for a second battery are not all that expensive. The wiring to relocate a second battery to the bed would likely be more expensive.

 

[Lil-Pony]

Yah but I'm an electrician and its just like hooking two 1.5 volt batteries in parallel you still have 1.5 volts but twice the available amps. Same thing with big batteries that are used in solar panels positive terminal to positive terminal. And negative terminal to negative terminal

 

[lil_Blue_Ford]

Yah but I'm an electrician and its just like hooking two 1.5 volt batteries in parallel you still have 1.5 volts but twice the available amps. Same thing with big batteries that are used in solar panels positive terminal to positive terminal. And negative terminal to negative terminal

That is true. But some people get the bright idea of hooking positive to negative and don't realize that they double the voltage.

One other thing is, both batteries have to be identical, if one is weaker than the other, the same thing happens that happens with wiring any battery in parallel - the weaker battery drains into the stronger one as the stronger one is pulled down and then the weaker one becomes a load on the system rather than a benefit. All sorts of nasty things can happen like the weaker battery heating up, and with a lead/acid battery like a car battery that releases hydrogen gas which, as we all should have learned in basic chemistry, is rather flammable. Or a battery could be subject to forces that cause it to explode. Or you might melt some wires or you might get lucky and it'll work fine.

I've studied electric, at one point I was seriously considering becoming an electrical engineer. House wiring and auto wiring are two different, but related, animals. Some things that are just fine for house or basic electronics are not so safe for things dealing with a battery that has a tendency to off-gas in a confined location next to an internal explosion engine. Not trying to say you're completely wrong, just that you need to be aware of slightly different situations. Don't worry, I had to learn the lesson as well.

 

[PanamaExpat]

You need to install something like this. http://www.ebay.com/itm/Perko-Marin..._Accessories_Gear&hash=item53f92ff9ef&vxp=mtr Here most boats run dual batteries as nothing would suck like being about 30 miles offshore and discovering you couldn't start your engines.

 

[wildbill23c]

If you don't want to spend about $100 for a battery isolator, which isn't very big then don't start adding batteries and additional electrical loads period. You want to quickly destroy your batteries and your charging system then go a head and install the second battery without the isolator, just don't come back here whining that your truck is eating batteries and alternators. Not trying to be an ass, but I myself am on an extremely tight budget, but I still know that if I'm messing around with electrical stuff in my vehicle I either have to wait till I have the money to do it right, or don't do it at all. People for the most part don't understand that the battery isolator will help protect your vehicle's charging system and main battery from damage due to overloading the 2nd battery. The isolator will save you money in the long run, and if you have a spare battery already for example that is older or newer than your current starting battery, then you definitely need the isolator anyhow to keep the weaker battery from draining the better battery, which it will do constantly, the weaker battery will pull power from the good battery and pretty soon both batteries are bad. The isolator prevents this.

 

[RonD]

Yes, two batteries in this type of installation need to be isolated.

The benefit of having a "starter" battery that will always be charged is one reason, another is that all batteries fail, period, a failed battery has a shorted cell inside so it drains itself, if connected directly to another battery it would also drain that battery.
Another reason is so you can run a deep cycle battery to power winch, plow or bad ass stereo, the deep cycle batteries are not good at starting engines, they can not release high amps as quickly as a "car battery", but they are great for steady long term amp draws, they can be discharged to low volts then recharge without much effect,
"Car batteries" can not stand this, they are made for quick amp release then recharge, if their volts get to low they loose their full recharge ability pretty fast and end up shorting themselves out, self discharging.
I.e. you can drive around all day and engine starts fine, if left overnight engine doesn't turn over in the morning, you jump it and it runs fine all day, WTF, next morning same thing won't turn over.
Battery has a shorted cell, it will charge but drains itself when engine is off.

 

[Lil-Pony]

Didnt think about that. Then why dont diesels have a battery isolator

 

[adsm08]

Didnt think about that. Then why dont diesels have a battery isolator

Diesels are designed to have the twin battery setup from the battery. In light of that the batteries are both new, and the charging system is designed to handle the load of two batteries. Also, you have to replace the batteries in a diesel in pairs. I have refused to service a customer's truck because he wanted one battery replaced and wouldn't listen when we told him it was an all or nothing deal.

I have also seen diesel's pop batteries because thy weren't replaced as a pair.

 

[RonD]

Yes, dual battery setups to start high compression engines are installed and replaced as pairs, in this type of setup it is, in essence, 1 battery with two parts, not two batteries, the reason they don't use one big ass battery(some do) is because two smaller ones are easier to deal with(Remove&Replace) and don't cost that much more.
And yes because there are two some want to replace just one, as adsm08 said that's a real bad idea, the one battery is 1/2 of THE battery for the vehicle.
Would you replace 1\2 the water pump or 1/2 the transmission, you can of course, but you shouldn't.

 

[Lil-Pony]

I like the way you put that ron, i was viewing them as separate entities when they are actually "one" in a diesel. So isolator is a must unless you plan to replace in pairs