Primary and Secondary batteries?

[devwayne]

Ok, another stupid question on 03 f250 6.0. Looked thru owners manual front to back. Which is the primary/starting battery of the 2 under my hood from the factory? The book refers only to the passenger side tho makes no mention of the other, so my guess is that one is primary? [img]/ubbthreads/images/graemlins/shrug.gif[/img]

[dwelch1]

your batteries are hooked in parallel, neither is the 'Primary' battery, the voltage will be the same!

[devwayne]

So there is no isolator between the 2 batteries? With accessories such a winch you are going to run both down? that makes no sense at all. The whole purpose of duals in the past was to have one isolated for seperate loads. I have a BSEET so I know the difference between series/parallel circuits.

[OT]

Takes alot of juice to crank PSD. Obviously u can run some acc. w/without e. running. Without iso./aux. 12 V batt. be careful. I know, been there/done that. [img]/ubbthreads/images/graemlins/biggrin.gif[/img] Good luck!

[ford_doctor]

[ QUOTE ]
The whole purpose of duals in the past was to have one isolated for separate loads.

[/ QUOTE ]

The purpose for having two batteries in vehicles equipped with diesel engines is for increased cranking amps. No other reason. Do not isolate one battery from the pair.

I understand what you are thinking and thats a good idea if you run accessories or have conversions requiring power. If that is what you need to have then I recommend ADDING a third battery as an AUXILIARY battery. There is more than ample room on the frame rails to add a battery box. Custom cables and battery post clamps can be made to suit your needs. You can charge the battery with the engine running and tapping off of the trailer tow 12V supply circuit which is relay isolated and fuse protected. I have seen this done. [img]/ubbthreads/images/graemlins/wink.gif[/img]

[GrampyJim]

To add to what Doc says... the frame mounted battery box from the Econoline can be easily aapted for use on other vehicles.

For everyone reading... the engineers do a lot of things that may look goofy to the uninitiated or inexperienced. One of the manufacturers major goals is to reduce production costs.... if something is "so", there will be a reason.

[devwayne]

Thanks FORD DOC, OT, & Grampy, it is appreciated. Jeez, how much cranking amps does this thing need. So I guess battery replacement will come in 2's, and maybe a matched pair would be good. I knew the only advantage of running the batteries in parallel would be to increase amps with voltage constant. So the third battery would be used with an isolator, correct? [img]/ubbthreads/images/graemlins/laugh.gif[/img]

[ford_doctor]

Corrrrr....rect! [img]/ubbthreads/images/graemlins/biggrin.gif[/img]

[frobozz]

[ QUOTE ]
Thanks FORD DOC, OT, & Grampy, it is appreciated. Jeez, how much cranking amps does this thing need.

[/ QUOTE ]

It's not just the cranking amps, which are high... it's the cranking amps in the cold when the engine oil is thick, which are higher... plus the glow plugs, which are about like throwing a crowbar across the battery terminals in terms of current draw (I think they're a couple of ohms each, all energized together)...and the glow plugs stay on for about two minutes, and while they are on, the alternator is shut off, since it couldn't hope to keep up anyway. So a "starting event" is quite a kick upside the head to the battery, and if you don't drive far enough to recharge it before the next start, things get bad fast.

I've driven a single-battery diesel in the winter before (old Mercedes) and trust me, the dual batteries is a ***GREAT*** idea! I guess Ford could just as easily use a single massive-amp-hour battery but nobody makes one and it's a lot easier to just use two standard stout batteries instead of getting someone to make a giant one just for them.

Duncan

[cmirabile]

[ QUOTE ]
I've driven a single-battery diesel in the winter before (old Mercedes)

[/ QUOTE ]

(Sniff... ahhh...) Fond memories

I remeber my mother had a old Mercedes Diesel with only one battery. Every cold cold morning before school, we had to hold the key in the glow plug position and watch the little coil glow just enough and then start it. If you didn't you were SOL, dead battery. Perfecct way to sabatoge the car if you didnt want to go to school that morning. And no one new the better [img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]

[GrampyJim]

Froboz is correct... the glowplugs will draw about 180 amps initially....when it's cold out, this is going to go on for about two minutes (remembering that "cold" is a relative term).

At the same time that the GPs are demanding this kind of current, the starter wants a big piece of the pie, too.

Sidebar.... we watch the Daytona 500 religiously and are amused at all the people bundled up in jackets and sweaters in the stands. In February, we can often get temps in the -30 to -40 range (Fahrenheit). At the same time, I am currently trying to work on my home addition but this past coupls of weeks has given us temps into the 80s (again, F) and I can't last more than a couple of hours in that heat.

[DunaticSuzyQ]

So, regarding battery replacement . . . I have one battery showing a "green" indicator on it and one showing "red". The truck seems to be starting just fine. Should I replace the (red) one or both? Also, one battery shows a lot of corrosion at the connector post and one shows none - what gives? Any insights would be great. Thanks!

[svsoccerpoker]

I have found that those indicators are'nt always right I would do a load test and go from there good luck. [img]/ubbthreads/images/graemlins/biggrin.gif[/img]

[AllOutFirefighter13]

[ QUOTE ]
So, regarding battery replacement . . . I have one battery showing a "green" indicator on it and one showing "red". The truck seems to be starting just fine. Should I replace the (red) one or both? Also, one battery shows a lot of corrosion at the connector post and one shows none - what gives? Any insights would be great. Thanks!

[/ QUOTE ]

I did my best to clean the posts on both of my batteries. After getting all the acid build-up off, I checked the water of the driver side battery. It needed just a bit, so I added it. This water was in a jug marked "Distilled Water" (which it MAY NOT have been) and the eye changed from green to red (which is why I'm thinking it wasn't truely distilled). But as svsoccerpoker said, get them load tested (if one or both is red).

On another note, these batteries are connected via a wire (unknown guage) that runs just atop the radiator (positive side). If you look at the passenger side battery, the wire coming from the driver's side is like a 3-way connection. The "T" part of it goes on the battery terminal, while the other "runner" is the cable that goes to the starter (I believe - maybe Grampy or Doc will confirm). This cable/battery may be the one people are referring to as the "primary" source.

Also, when cleaning mine, I noticed the cables are screwed to the clamps that go on the battery post. In the event that the cable coming from the driver's side develops even minute corrosion between it and the clamp, more load will be placed on the passenger-side battery (given the corrosion build-up to be between the clamp and the driver side cable), so it is a good idea to take these apart and clean them well to keep a near 0 ohm resistance. With the internal impedance of the batteries and the impedance of the starter, even a few owns (no more than 10, possibly less) can cause a significant voltage drop across this point, which ultimately reduces current-flowing capabilities. This is primarily what causes a slower-cranking engine. You'd be suprised at how "stronger" the starter will sound by just cleaning ALL the connections (and ultimately restoring the near-zero resistance to the electrical path).

[fullservice]

When you add water, you dilute the fluid and lower the charge in the battery. Probably nothing to do with disitlled or not distilled water. After engine has run long enough to rebuild charge in the battery you added the water to, the eye will probably turn green again.