Can i just Wire the postive terminal straight over the radiator "Avoiding the heat" to my other optima battery and the negative to the block?

 

You can tuck the battery cable on the top rail of the radiator support. Can put some black electrical coil wrap to help keep the wire cool and the appearance cleaner.
_____
Buck

 

You are better off with a battery isolator.

The heat to a 0 or 1 gauge cable running along the firewall like Ford did would be negligable.

 

Use some type of dual battery component, do not run the other battery cable directly to the other battery with out some type of battery isolator or dual battery component setup.

 

I ran a battery on the drivers side, to my solenoid on the passenger side, and it works fine.

 

Moved to proper forum.

Use an isolator available from any RV supply house. DO NOT hook them up in parallel which is what you are talking about. There are a number of threads on this subject in this forum.

 

I have two batteries wired the second in through an isolator. Primary battery runs the truck and the standard stuff, winch driving lights, brake controller etc run off the second battery. With the isolator always have a full battery.

 

Battery Isolator:


Easy to hook up. Alternator to center post, a battery on each outside post, everything shares a ground.

The alternator can charge both batteries simultaniously, but the two batteries can't see each other at all. So whatever is "stock" in your truck would go to the primary battery, and all the "other" add on stuff (600W of roll bar lights, electric winches, ridiculously overpowered car audio stuff, etc, goes to the second battery. It's not uncommon to use a regular car battery as the primary battery for the vehicle, and a deep discharge type battery (Optima, for example) for the secondary battery so you could run the car audio stuff until the battery is dead, and still start the truck and drive away.

The less costly units typically contain two high current diodes which the entire isolator unit is a heat sink. More expensive units often have "deep discharge disconnect" features where you could in theory drain the battery most of the way down, but leave enough "oompth" to start the vehicle at least once.

I have a battery isolator and two batteries in my FWD Continental. As described above, one battery is for the car and it's normal plethora of electronic gizmos, and the second battery is an optima, for the car audio stuff exclusively. When I put the audio system into that car back in 94, I'd often play volleyball in a field and we'd listen to the radio or cd's from my lincoln. Often for many, many hours.

 

Most everyone uses and isolator, and I would recomend and isolator as well. However, you can hook both batteries in parallel as that is the same way it is done on diesels with dual batteries to increase starting capacity. Doing it this way, you still have the possibility of running both batteries down and not being able to start.

 

I know I am going to get blasted on this one as it seems every body thinks the battery isolator is the way to go but here are my two cents.

I have a FORD Class "C" E350 with two batteries, Onan generator with factory wiring with no battery isolator.

My RV uses starter type solenoids, it starts on one battery unless I push and hold a push button that puts them in parallel for emergency starting if the 460 is turning slow. It charges in parallel after the key is returned to the run position. It has two starter type solenoids, one comes on when I push the button and the other in the run position.

It also charges the deep cycle battery when the RV is on shore power or the Onan generator is running.

I do not see how a battery isolator could possibly work if they contain two high current diodes isolating the two batteries.

With the battery isolator what I do not see is how the Voltage regulator would know what the charge is in each battery and know how to operate the Alternator. With diodes blocking the voltage level coming back to the regulator it would not know what to do.

If a battery isolator is so good how come the RV Manufacturers do not use them, and why are they just an after market product.

I think battery isolators are just a rip off.

I have never look into a battery isolator but if some one could show me how this thing is wired in ... (a diagram).
Does it just isolator the starter from the other battery?
The starter type solenoids are cheaper and work great so why not use them?

 

The isolator is basically diodes placed in the charging circuit only. The heavy wires are still connected directly from the battery to the their loads.

Some drawbacks to the isolator that I can find are:

The approx .7 volt drop through the diode. This means the alternator puts out say 14.5 volts, but the batteries only see 13.8 volts. Some people worry about it and modify their regulators for more output, most people don't worry about it.

There is not a problem with most alternators sensing circuits, because most have a extra remote wire for this that is tied into the vehicles electrical system. But there are some vehicles with a self exciting alternator, that gets it's feedback to start charging through the charge wire itself. In these cases, the have special isolators for this situation.

The good thing about them is there is no thinking involved to operate them, unlike the relay type.

The relay set-up is ok, but it has a few drawbacks too. The ones I have found are:

When a relay is closed, if one of the batteries is way lower in charge than the other, then there is a large rush of current from the higher charged battery to the one that is lower charged. They say this can cause the batteries lifespan to be shorter.

The wiring and switching can be a little bit complex sometimes, depending on what you are trying to do. It is not as dummy proof as the isolator installation can be, though the isolator can be complex too if you are doing aux starting.

I think it's like everything else, each has it's own drawbacks. You can forget the whole business and hook the two batteries permanently together, but then you just have one large battery with not much flexibility. You can do a lot of neat things if you isolate the second or third battery either by relays or an isolator.

 

"I have never look into a battery isolator but if some one could show me how this thing is wired in ... (a diagram)."
In our fleet we have 50+ Goshen handicap busses, E450 7.3 PSD's and they all run the 2 original Gp.65's in the front and an Gp. 8-D under the body, using a Cole Hersee 48161 or 48162 battery isolator. Good/bad, I don't know but that's how they come.

http://www.colehersee.com/pdf/IFs/IF-128_Bat%20iso.pdf

 

Subford:

I think that the way you do it is the only way to go if you want to have your secondary battery available for cranking power.

Most setups, using the isolator, are wired so the loads for the two or more batteries are totally separate and cannot be used for the same loads. So if you needed your secondary battery for cranking you would have to use jumper cables.

Anybody, am I mistaken?

 

For all but the fanciest Isolators you are correct. I used the trailer tow charge relay for my aux battery for quite some time. But wanted an isolator fto charge the aux battery and trailer batteries quicker with the truck idleing. Relays are great as they are simple and allow current flow in both directions, some cases good, some bad as Franklin stated about the huge rush of current can burn stuff up.