Insufficient Electrical Power

[jluyk53]

Got a couple questions. Hang in there, I'll get to them eventually..

We have a 12v battery running through a voltage regulator. We have a heater installed and had it was disconnected as we were told when we bought the CJ that it kept draining the battery. We then connected it to the starter coil so that it would only run when the CJ was running. Then, two days later our CJ refused to start. I had driven it for a few miles and parked it (illegally) then had to move. It started fine so I was able to move to a new parking space. Once done with my errand I went to start it and.. nothing.

Would driving with 12v headlamps on for 20 minutes the night before and the short drives coupled with the newly attached heater drain the battery like that?

Also, when we turned the heater on, the engine started to dog pretty bad. Why is this? Is it simply too much draw on the generator?

[RussellL]

Your generator or alternator must not be working at all. �The battery is only there to start the engine, then the generator should supply enough power to charge the battery back up as well as run all electrical equipment. �That includes the ignition and the heater. �If the generator is not working and the battery is nearly dead, any extra electrical load will starve the coil of enough power to make a proper spark. � If the battery is poorly charged or going bad, then yes using the lights for 20 minutes can run it all the way down if the generator is not working. �If the battery is in good shape but discharged, it can take anywhere from an hour to several hours to fully charge, depending on the size of your charger. �It may seem like it is charged, but it won't last as long under load as it will when fully charged. �If the battery is charged and the only drain you put on it is to start the jeep, then the generator will charge it back up in just a few minutes. ��If the battery is going bad, it may not be able to take a charge. �No amount of charging will bring it back to full, and if it does take some charge it will run down quickly. �

The heater should be hooked up to the ignition switch so it is off when you turn the key off. �That may be what you mean by starter coil? �Using the ignition wire going to the coil? �I would not hook the heater up to the coil, though. �It might be using too much power for that wire, and if your ignition circuit has an external resistance on the coil then it will definitely affect the power going to the coil. �Better to hook the heater to the back of the ignition switch. �

[jluyk53]

We just disconnected the heater since we only drive it in warmer weather. We have since replaced the 12v headlamps with 6v ones since one of the 12v ones died. When I got home, after being jumped, I charged the battery and it's been fine since, no problems starting. We haven't tried reconnecting the heater since. Perhaps I'll tinker with it tomorrow..

Thanks,
Justin

[RussellL]

Didn't realize you were using multiple voltages.  Trying to run a 6v jeep with a 12v battery makes the electrical system much more prone to problems.  Why not just get a 6v battery and run it correctly?  

[Carls_jeep]

You will have to switch to a 6v battery like Russell said. it's not a good idea to run a 6v system with a 12v battery. Your going to have all kinds of electrical issues doing that.

Also, the heater should have a separate switch so you can turn it off when you don't want it running.  

[jluyk53]

When we bought the CJ it was running a 12v battery through the voltage regulator. Now that we've replaced the 12v headlamps with 6v ones, all the electrical components are 6v. We were told by the gentleman who sold us the CJ that 12v was better, but he failed to say why.

So, what are the advantages of a 12v battery, if any?

The heater does have a separate switch for low medium and high but its a really old switch and I think it needs some work. It seems loose and low doesn't work.

Thanks,
Justin

[Carls_jeep]

The question is, do you have a 6v generator, a 12v generator or a 12v alternator. The 6v bulbs won't last long running on 12v.

If you have a heater with a motor in it the motor will burn out running on 12v. You can use a resistor to reduce the 12v so it won't burn the motor up or you can get a 12v motor that you can make work in your heater.

Do you have a 6v coil or a 12v coil. You can put a ballast resistor on the 6v coil to keep it from burning out.

Does the amp meter show a charge?

[RussellL]

The 12v battery will make a 6v starter spin very fast, so starting may seem more powerful.  But unless the charging system matches the battery, it won't charge the battery.  Not sure what you mean about using the 12v battery with a voltage regulator.  That is not an arrangement that I am familiar with.  I don't see any way that such an arrangement would allow the charging system to charge the battery, though.  

[Carls_jeep]

He could have a 12v generator with a regualtor or an alternator with an external regulator. I'm not sure he knows what he has.

Personally, I think he needs to get a mechanic involved in his Jeep to find out what is going on. It's obvious the last owner didn't know what was going on from what he is saying and is probably one reason they sold the Jeep.

[RussellL]

I agree.  I think you need someone who knows electrical systems to go through it help you get it set back up correctly.  A 6 volt system will work just fine if it is maintained correctly.  

[Gunslinger]

Justin,
Here's some insight from a guy that did his 12 volt conversion, but did it wrong, or twice whichever you choose.  I converted to 12 volts because my 6 volt generator was shot and it was cheaper to buy a 12 volt single wire alternator, and I wanted to be able to add some current trickeration when it came time to upgrade the beast, like an electric winch, additional lighting, radio... all that stuff is easier to find in 12 volt.

So here's the stuff that needs to change:
Headlights - 12 volt
parking and tail lights
coil has to be 12 volt with a ballast resistor as 12 volt coils run on 8 volts, 6 volt coils will distress and crack internally due to the heat and then you get to walk home or sit by the road waiting for the coil to cool back down, ask me how much a medium pizza weighs after walking 3 miles listening to a not so impressed wife...
new fuel tank senders are 6 or 12 volt, they work on either, old one, change it
gages are the same, new ones take either voltage, old ones melt
dash lights especially the tattle tail have to change as well
Starter motor will work on 12 volts, it spins faster, just be prepared to have to replace it sooner, and it may wear you ring gear down faster as well.  I've been running on 12 volts for 3 years now, no issues with the starter motor, I drive about once per week.
Alternator/ Generator, it all starts right here, whatever you do at this point you have to do with the rest of the vehicle.  

I think I got it all, but as you can see the conversion is not hard, its just got to be complet eor your gonna have problems.  While your at it, its just as easy to replace the wiring to make sure youve got it covered..

PS, Voltage regulators control the direction of electricity from the generator to the battery/ ingintion, they control the charging circuit, they do not adjust the voltage up or down.  voltage is the same as pressure, amperage is flow, watts are the consumption of the device you are running, ohms is how hard you have to push the electricy to get it where you want it, ohms cause heat. ie resistance.

[jluyk53]

Wow, thanks for all the great information guys. I really appreciate your inputs.

I now know I have been using the wrong terminology. I have a 6v resistor(?) that reduces the voltage coming from the battery. I have a 6v generator, not an alternator, and a 6v starter. All of these are powered by a 12v battery through the resistor.

New question: Would it make sense to just get a 6v battery and ditch the 12 if I don't really need it?

I think our next project will be to replace the befuddling tangle of old, fraying wires with an all new wiring harness, once it's in the budget.

My father and I are working on this project together when I'm home from college and couldn't do it without your advice.

Thanks again,
Justin

[RussellL]

Absolutely, you should try to get back to just having one type of system.  If most of your components are 6 volt, then I'd just get a 6v battery and go from there.  You might find once you put the 6v battery in that there were some problems, like a weak starter,  that may have been the reason the previous owner tried using the 12v battery in the first place.  But it is definitely better to just fix those issues correctly rather than invent oddball solutions that usually cause more problems than they solve.  

One thing to pay attention to is the battery cables.  A 6v system uses very thick cables because of the high amperage feeding the starter.  Many times someone thinks they have a problem with a weak starter but it is because they installed an aftermarket cable that was intended for 12 volts.  Those can't handle the amps of a 6v system.  A proper 6v cable will be about as thick as your index finger.  

You will also want to get the generator charging system checked out to be sure it is charging properly.  

[Carls_jeep]

Yes, get the biggest 6v battery that will fit in your battery box and be sure to get battery cables for a 6v system.

You can rewire it yourself without a wiring loom. Just replace one wire at a time and that way you won't get messed up.

The wiring on these Jeeps is simple but you can make it as hard as you want to.