Okay. So I now have a voltage gauge to monitor my voltage. The batteries are new and are maintaining around 12.5 volts when the vehicle is off. Cruising on the hwy maintains a voltage in the 14 range. I am wanting to do some things to help the system charge better and not draw as much when starting. The GP will drop the voltage to the high 10/low 11 range. Starting sees the voltage drop lower when cranking. I already have new positive cables. I will be replacing the voltage regulator. Going to clean up the grounds and replace the negative cables if needed. Are there any charging wires etc that I should replace with thicker gauge wire to reduce resistance. Will replacing the positive cable and cleaning the grounds help it charge better?

My next step maybe a new starter and a g3 alternator upgrade.

 

What year is your truck? Do you know what alt you have now?

 

Your numbers are identical to mine. Nothing seems wrong if you ask me.

Mike

 

Its the van in my signature. '88 e250. Alternator is stock........most likely original.

 

Thanks for the input. Its not that I think the numbers are bad. They r probably fairly normal. That doesn't mean that I can't make an improvement on performance. If I will reduce the resistance of the system it should perform better. Less voltage loss and better charger. I'm just not extremely knowledgeable on the system, so I need a little help explaining the flow etc.

 

the voltage regulator see's the system voltage, and sends current to the field of the alternator to control its output, the charge from the alt should connect at the long post (binding post) of the start relay on or near pass side fender,(this binding post is just a convenient place for ford to connect to batts) if one was to increases the gauge of the charge wire it would not make significant improvement, unless you up grade to larger out put alt, then larger might be needed. the charge rate and voltage are set by manufacture. if you up grade the Alt, upgrade the regulator also. my .02g GO SEHAWKS

 

You don't want too high a voltage; 14.0 is fine. Remember, lead-acid batteries start gassing at somewhere around 14.4(according to wikipedia), which isn't good for anything.
You aren't going to charge your batteries with anything more than they will take. Increasing the current capacity of your alternator will do exactly nothing, unless you've drained your batteries a lot. Once you're up in the 14V range, things are basically fully charged already, so all you're doing is supplying power to the fans and electronics in your truck.
If you manage to 'hack' an alternator to put out a higher voltage, all you're going to be doing is shortening the life of the battery by overcharging it and electrolyzing water into oxygen+hydrogen(which will either mostly get combined back into water in the battery caps, or lost, so you'll have to add more water).

Discharge wise... Upping the wire size to the glow plugs is likely to bring the voltage of the batteries /down/, not up, as there's less resistance in the system and thus more current.
Also, 10V is perfectly fine when cranking. You're drawing a /lot/ of current in the starter, and this is expected.
If it was hitting down in the 9V range, then you might want to worry.
Thickening the wires should help a little with cranking speed, but will do nothing or /reduce/ the voltage of the batteries as the resistance drops.

Honestly, don't mess with it. You don't have anything wrong with the charging system or starting system, and unless you're getting physical issues -- not turning over fast enough to start the truck etc -- be happy everything is working.

 

I am not trying to increase the voltage. I just figured if I was able to reduce the resistance I may gain more efficiency. The greater efficiency could help the components work to their full potential. Kind of like when you replace your battery cables and the starter turns over better in the same conditions. Wouldn't less resistance to flow help reduce voltage drop throughout the system? Also, the voltage regulator will regulate the voltage, but I thought a lower resistance charging wire might allow for better charging at lower rpm's.

Thanks for the feedback. I just figured since I will be messing with it a little why not try and upgrade it a little.

 

It's true "too high" is bad, but the correct charging voltage is temperature dependent. 15 volts, is required for cold temps, for example, but it would be a big no-go for a warm summer day. Moderate gassing is fine, you WANT to see that, because gassing starts at around 80% charged. Basically, a battery won't even start reaching full capacity until the charge voltage has reached about 2 (two) volts above the open circuit voltage, in automotive start batteries normally about 12.6 to 12.8 volts.

If you look at battery charging profile tables they show several hours at the absorption phase, around 14.7 volts or so. The current starts out high and decreases as the charge voltage increases, held there, then switched to float. It is important to have good ventilation whenever batteries are being charged, because of gassing. The fumes are not only flammable, but toxic.

 

You're describing a three-stage charger.
This is all good in theory, but I'm pretty sure no OEM alternator systems actually do this.
The best you will get is a temperature-corrected voltage-regulated system.
Part of the problem is that in a vehicle situation, due to the various loads which may(or may not be on) mucking with the voltage; a smart charger would have horrible trouble knowing whether this small dip in voltage means that it's reached a charge point, or because you've turned on the headlights.
As such, vehicle systems are sub-optimal, though batteries these days seem to be able to cope well enough with them.

I'm also pretty sure that vehicle systems will /not/ put out 15V period, if only because that's high enough it could potentially damage electronics and such. However, this shouldn't matter too much, as the batteries are inside the engine compartment, so as soon as the engine warms up, so will the batteries.

You are missing out on the fact that most batteries these days have recombiner caps -- Usually a little bit of a catalyst to try to get the fumes(oxygen + hydrogen) to recombine into water. This is how 'maintenance free' batteries work(remember, any gassing that escapes the battery == lost water which needs to be replaced).


Think about it this way: You have a circuit:
+ ----(wire)---- (bulb) ---(wire)--- -
If you have 12V between + and -, that voltage will be dropped across the entire circuit.
The resistance of that entire circuit determines the current, and thus, how much power it uses(P=IV)
Some of it will go to each of the wires, some to the bulb. If you reduce the resistance in the wires, you:
1. Reduce the amount of voltage dropped across the wire, reducing the power wasted.
2. Reduce the amount of resistance in the circuit, increasing the current.
This will make the bulb brighter(slightly), reduce heat in the wires etc.
You won't gain any real efficiency(as in MPG-level) because the lower total resistance means a higher current across the circuit. You just get better brightness from your power.

Now, as far as the charging circuit goes, remember that E=IR(voltage = current*resistance). If you have a noticeable amount of resistance in your charging wire, it will be most noticeable when current is high. When the current drops off, the voltage drop also is reduced.

As such, you can only really tell if your cable is limiting /at all/ when your batteries are drawing plenty of current. You can then put a multimeter between the alternator post and the battery, and see what, if any, voltage drop there is.

Thing is, though, if you're charging at 14+V already, any gains are miniscule already and you shouldn't worry about it.

The reason our charging system cuts off at a certain RPM has less to do with resistance in the wire than the fact that alternators & AC generators don't tend to produce much if any output below a threshold speed.(Ref: http://www.redrok.com/cimtext.pdf ) If you wanted to improve idle charging performance, put a slightly smaller pully on the alternator. This will make it spin faster for the same given RPM, and thus have a higher output capacity.

To be honest, I'd expect to get more bang for your buck with either a smaller pully, or by cleaning and then sealing all the wiring ends. That's where you'll get most of your resistance, and what's most likely to fail.

Then, take your money and put it towards improving other things.

 

No, even simple "dumb" chargers like Schumaker have sold for decades are sized for automobile start batteries and work much the same way. The big advantage of a smart charger is it's OK to leave them connected.

But - hang a voltmeter on the battery and you can watch this, either with a smart charger or anything else. They are usually a taper charge - current starts out high and decreases, while voltage increases. It's possible to overcharge a battery but it takes dedication.

Voltage Regulator specifications for my 64 indicates that a voltage of 15.1 to 15.9 is indicated for 25F with a generator, 15.0 with an alternator regulator, etc. Hope this helps!

 

]
I'm not sure you understand what you're saying. The current decreases because of the /battery/ not because of the current available from the charger(*)
Try this yourself: Find a constant-voltage source, lets say 13.8V. Hook it up, and you will see the current decrease as the battery charges, not because of the charger, but because of the simple physics of the battery.


(*)Note: In addition to this, 'dumb' AC-transformer chargers have a second problem, and that is sizing of the transformer. As there's no regulation of the voltage, in order to be able to supply a decent current at, say, 12V, the unloaded peak voltage is above what is healthy for the battery, but as any battery becomes a load(electrolyzing water, if nothing else), the battery will keep the voltage from rising *too* far. Due to the sinewave curve of AC, the charger can only supply a tiny bit of current at that peak voltage, so there is little electrolysis going on.

Modern switching supply-based chargers, alternators and the like don't have this problem, as they are regulated to a given voltage with a feed-back loop; so they can(and will) supply maximum current at their rated voltage without a high unloaded voltage.

The other thing to be aware of is that, in a load-connected-charging-system as in a car, where the charger is connected to the battery *and* loads at the same time, the charger can't produce more voltage than is safe for the load. I'd be very worried if I ever saw 15V on any of the load lines, because most car electronics aren't really rated for it.
Bulbs will likely take it without issue, but burn out faster.

Don't know what' you're saying here. What's your '64'?

 

All right. I will plan on cleaning up all the ends etc, Insuring I have good grounds and then inspecting the wires for any damage/corrosion.

The thought of a slightly smaller pulley sounds kind of interesting. May have to look into that. So does anyone know if Ford adjusted the pulley sizes on the diesels to make up for the lower RPM's? Wouldn't want to cook my alternator by over spinning it.

 

Yes, the charging CURRENT rate is determined only by how much the battery will accept with a typical "dumb" unregulated charger. The charger current decreases, the voltage increases.

I get that, and this is why I suggested people hang a voltmeter on their battery while charging (whether a BT or Schumacher or whatever) so they can SEE what's going on while they look at the charging algos. It's not intuitive but it ain't rocket science either. http://www.batteryfaq.org has charts showing typical charge rates for many types and they are all way higher than 14 volts, and for several hours.

The voltages are different for different types of batteries, high and higher. Five-tenths of a volt doesn't sound like much but on a percentage basis it's huge and it's important to charge expensive batteries to their full potential. What many people do in my experience anyway, is charge a battery juuust enough till it reads 12 or maybe 13 volts (or starts the engine) but no more. Batteries are called "12 volt" but a maintenance free battery measures 12.8 volts open circuit at a full charge. And maybe that's part of the issue.

Batteries won't actually charge up at their advertised voltage - they require application of about 2 volts above and beyond that. You're right, excess current and/or excess voltage is bad, but moderate gassing is necessary to fully charge a battery, there's no way around that, because gassing starts at around a 80 per cent charge. Periodic charging up to 16.25 volts is recommended for non-AGM batteries! (For safeties sake, as you mentioned these voltages should not be applied when the battery is installed.)

As it happens the retail chargers are just about perfectly designed for a big 800 CCA auto start battery. On the two ampere setting the actual end current is maybe 100 milliamperes and around 14.5 volts with a Schumacher dual rate. It would boil a battery dry eventually but it would be tough to hurt anything this way.

 

Your starting and charging system is flawless. All your numbers are high on the scale. If your battery voltage is more than 9.6 volts you are doing great.