I did own a chevy dura(fill in the blank) and found the fuse for the glow plugs, it was something like 175 amp. i am not sure what fords is but is has to be close to that.

 

I seem to remember reading somewhere that it was on the order of 40 amps per glow plug. I also recall that these glow plugs were to heat to 1800C in 3 seconds.

 

YEEEHAAA...that is hot and quick

 

Let's face it, a diesel having two batteries is a very basic thing, and common knowledge too all of us. On many other forums, someone asking this type of question would have gotten the poor guy flamed all to hell, being it in jest or actual ridicule. There was not even a hint of ridicule, joking or otherwise, in any of the responses posted to his question. In fact, it turned into a very informative thread teaching myself and I'm sure many others, more about my 6.0. I had no idea that the glow plugs used that much power. Nor did I know I will need to change both batteries if one goes bad. All I have too say is, it's a pleasure coming here.

Now, if I could just get you all to proof read your posts

 

Now we must speel right and use grammar correclty ? I thought you is asking too much

gues me cant post here nomore



LOL

 

Just to back up a little, yes. You should replace the batteries as a PAIR.

You could replace one at a time, but you will end up changing the other one shortly afterward anyways, and the damage to the new one will be done already. You'll be chasing batteries all over the place until you finally do both.

I run into this problem all the time with big trucks. An owner of a truck will try to save a hundred bucks by changing 2 of 3, or 3 of 4 batteries, and a couple months, sometimes a couple weeks later they're back for 3 more. So they bought 6 batteries when they only needed 4.

Even if your second battery is still good, change it out. You can always keep it as a spare. Or use it as a jumper battery for something else.

 

Having a civil forum seems at times to ruffle some feathers, however it is sure wonderful, when all pull together and accomplish a dream and goal.
The most informative and well managed information source available for the Ford truck.
The reason it works, all of you, the best members... on any site.

 

I have an 04 SD with 6.0TD that has dual alternators. I can (I think) understand the concept of changing both batteries together if they have a common charging system. Is it still necessary if each battery has its own charger?

 

In general, it's what happens when the charging system is off that matters. When the charging system is on, voltage is held at the level dictated by the voltage regulator (hence the name).

When the charging system is off, if one battery can charge the other, the newer battery will be degraded by charging the older battery. This occurs because the nominal voltage of the newer battery is higher than the nominal voltage of the old battery. Because storage batteries can develop rather large amperages due to low internal resistance, the old battery will drain the new at a fairly high rate until the new battery's voltage drops to equal that of the old.

In this case, the new battery may be nearly 1/2 discharged while the old battery is holding the maximum charge that it's still able to keep. As you should know, spending the majority of it's time with 1/2 a charge will cause the new battery to age (sulphate) rapidly.

In a truck with dual alternators, it is not true that each alternator charges one battery. Having had a gander at the ford documentation for dual alternators, the batteries are both on a common bus. The alternator wiring itself was more complex ... but dual alternators do not change the way batteries are connected to the system.

If you have a device (called an isolator) that separates electrical systems, then you can replace the batteries on different schedules. A common example of this are trailers and motorhomes that have separate battery systems for the "house" power. These systems are isolated from the truck battery systems by an isolation device. Some are more complex than others, but generally, they allow the house batteries to be charged when the truck is running and disconnect the systems when the truck is off.