The Stovebolt Site Forums The Shop Area The Electrical Bay 6 volt to 8 volt

My regulator was tweeked to 8 volt by the person I purchased the truck from and an 8 volt battery was installed. I have a 6 volt trickle charger on it and it doesn't seem to want to keep a charge. Am I missing something here. The manufacturer of the charger said this would work.
Thank You for any help you can give.

Yea! 8-6= 2. They teach us that here in Texas. Your'e 2 short of 8. Why 8 in the last place?

Or is it 1st place? How can a manufactured 6 volt charger put out 8 volt's? Kan't, as they say here in Texas.

Welcome to the Stovebolt Forums.

My bet is the guy who put the 8V battery in it first put 12V battery cables in it. These are smaller diameter cables and are not sufficient for 6V use. So he then decided to go 8V. If he had used the proper cables to begin with the truck would have been just fine on 6V. Just my guess.

If the 8V battery is needing a constant charge it's probably due a replacement anyway. My advice would be replace it with a 6V, replace all the cables with 6V cables and be sure all your grounds are clean.

Cletis is right on!! These ol trucks worked for years and years on 6v,,,just as they were designed to do. BUT,,usually,somewhere along the line someone replaces a battery cable with the wrong size. Then the problems start.
With good clean grounds,and the proper size cables,,we're talkin diameter,and length,, it should work like it was designed to work.
Just talkin from past experience........
Good Luck,Marty

My bet is, the 8 volt battery will spin the starter a little faster, make the lights a little brighter and they can be found at about any tractor dealership. The downside of this, the bulbs don't last as long.

I've got an 8v battery in my 53. After tweaking the regulator it has been doing just fine, no unusual problems with the bulbs either. That said, if you need a new battery do as Cletis says, go back to 6 v. My guess is that your guy (and my Napa guy) had 8v batteries in stock but no 6v. Those 8v things work well on the farm, so why not in a truck? That is the line I heard...
I would wonder if the trickle charger is too fickle, I charge my 8v with a standard 6v charger.
Karl

If you go back to 6V, you would be wise to fix or replace the regulator.

IF you have a good starter and charging system.
IF you have properly sized cables.
IF you have an Optima 6V battery.
IF your grounds are all good & clean.
You will NEVER have a problem with a 6 volt system or a reason to use 8 volts.

Amen

You never stated what the guy tweaked the regulator out put to. That Should be somewhere about 9.5 volts. Unless the 6 volt charger will puts out over 9volts it is not going to keep the battery up either.
I agree with most of the guys here 6 volts works fine as long as the cables are the right size and the regulator output is set at 7.4 volts. I found in the day that 8 volt batteries where just a crutch to get a guy by instead of rebuilding a "dragging" starter.
Another problem I have found is that most repairs are not made with the correct size wire and most after market wiring kits are not supplied with the correct size wire for the 6 volt headlights. I think that may be a two way street also since most comsumers fail to mention to the supplier of the wiring kit that they are planning to use it for a 6 volt application. Dim headlights due to small wire drastically increase the amps required to burn the headlights, thereby discharging the battery more than nessecary.

I don't think inadequate wire size would cause the headlights to draw excess current. The amount of current a device draws is a factor of its design, not of how it is wired. Does this sound right!

Stuart

I agree with you Atomarc. Smaller wires would if anything restrict current flow not increase it. The smaller wires used for 12 volt service would run a 6 volt system but of course the wires run hotter due to higher currents in a six volt setup. Turnkey21 should measure the output of his charger with a voltmeter. If it is higher than the static voltage of his battery then it will charge it. The closer his charger output is to the battery voltage the longer it's gonna take.

I am no expert on the matter, but if the smaller wires are running hotter, then that heat is drawing power from somewhere. I should think that the smaller wires will run hot, with increased resistance, less juice to the lights AND more draw on the battery.
I set my regulator for a little over 9 volts, but I tried not to run much over that to let the bulbs last a little longer.
Another thing to consider, Turkey, is that there is a chance that the guy who tweaked your regulator mis-tweaked the cutout relay at the same time, so that the generator drains the battery at idle. It might not be a bad idea to have someone you know to be competent look over the whole charging system.
I wish I had found this site before I did the 8-volt shift on my own truck, but it works just fine at the moment. I'll be going back to 6-volt when this battery dies.

Sorry Organbuilder, but it doesn't work like that. We use a law called "Ohm's Law" which states I (current) = E (voltage) divided by R(resistance). In this case voltage and current will be consistered "constants". So the current is what it is. Those of us who have been designing circuits and popping fuses for several decades know there are other things like heat/resistances coefficients at work here. But, when your up to your arse in grease and wiring harnesses the above law will "get 'er done".

I just can't let this thread die away like that. I am a faithful follower of Brother Ohm, we're old friends. Voltage in a truck certainly should be constant, but current usually isn't. That's why we have fuses. If current were constant we would never pop fuses. It all depends on what a circuit is drawing, and if it is drawing too much that can depend on a lot of things, that is where a good troubleshooter comes into the picture, and that is why I follow these posts. I must be misunderstanding Beltfed here, I am sure he is ten times the troubleshooter that I am, but it really doesn't matter because we are way off the original topic.
The question here was about charging an 8 volt battery, not about wiring for headlights and Ohm's law. And I have current personnal experience with an 8 volt battery. Once in desperation I even tried charging it with the trickle charger for my MC. I charged the battery for 2 days without a noticeable effect, then I borrowed a big grown-up charger (which I still have not returned after a year) and after a few hours had a charge on the battery that started the truck.
So, it is possible to charge an 8 volt battery with a 6 volt car battery charger. In my experience the voltage of the charger is not the problem. I would guess that the problem was that the trickle charger was a 1 amp device, the big charger a 20 amp. When charging a MC battery the trickle charger is still supposed to charge overnight, I think it said over 12 hours for that dinky little battery. Maybe it would work to charge a car battery with a trickle charger if it sat and charged for a week.
So here is a follow up question: has anyone successfully charged a 6 or 12 volt car battery with a trickle charger?

Sorry Organbuilder, I made a typo. As you noticed, it should read resistance and not current as the constant.

Well, even then, if voltage is fixed and current is variable, then according to Ohm's law resistance must also be variable.

I don't mean to be a jerk about it, it's just that Paulweldit might have a point about wire size, it could be one factor in a charging system that doesn't keep up. It is still a bit off the subject...

Organbuilder,

A device will draw a specific amount of current when operating properly. The design of the device determines that value. In a electrical circuit, if there are no loads connected, there is no current flowing! The headlight will draw its designed load...undersizing the wires supplying it will not make it draw more current.

Insufficient wire size will strangle the headlight, make it dim and the wire will heat, but it will not make the headlight or the system draw more current. This is how I understand it.

Stuart

Stuart is correct. Ohm's law is not being broken.

Trying to cram a large amount of current through a wire that is undersized will create heat on the wire.

Heat is a sign of resistence, which makes sense, seeing as not all of the current is getting through to power the lights. The current that is not getting through to the lamps is converted to heat energy. This is basic high-school physics. Have a look at the law of conservation of energy some time.

As a point of interest, this is the way that Rheostats work (variable resistors, like a dimmer switch on your dash lights or the fan switch on your heater). They use special wire called resistence wire that drops the current down to the desired level, but in order to satisfy the law of conservation of energy, there's heat generated. The higher the resistence, the more heat is outputted, and the less current is passed. If you've ever touched the back of a rheostat switch like that when it's been on and burned yourself, you've experienced this physical law first-hand.

And that is what I meant in my first post, Brendan. The lights are drawing their specific amount of power, but if the wires happen to be undersized so they are heating, they will draw some current too. Maybe not much, but a little. And electric heat is an inefficient form of energy, so the loss in the wires might be considerable.
And I am still curious about charging car batteries with trickle chargers.

Organbuilder,

The headlights are powered by the battery. The battery supplies voltage, say 12 volts, and also has the capability to deliver a HUGE amount of current. This huge reserve of power in the battery is just sitting there waiting for something to use it. The starter uses lots of current, the headlights use a little current, the coil uses only a tiny bit of current. These things only use what they were designed to use. Although this huge reserve is there waiting, the coil would never use the current that the starter would use even though it hooked to the same battery. Voltage is present in the wires all the time but nothing flows until the headlight is turned on and 'asks' for current.

The trickle charger must produce enough voltage to overcome the battery, but the 'trickle' part isn't voltage, it's a trickle of current.

Stuart

It seems that we have about 8 topics going at the same time, and I am sorry that I am not expressing myself well on any of them. All this stuff about current and Ohm's law and wire sizes is not directly related to the original topic. As I see it, one part of the original question was: with a battery disconnected from the vehicle, will a trickle charger over time be able to charge a car battery?

Organbuilder,

Sorry for ranting! I think a trickle charger will be able to charge a car battery over time if it is designed for that batteries voltage. A 6 volt charger will not charge a 12 volt battery to full capacity.

Stuart

Has anybody tried this?

My uncle uses a battery tender on his harley in the winter. I don't see why an 8v trickle charger wouldn't work.