1955 Battery just caught fire on Sunday drive

I have been following this post and a few comments that I have regarding positive ground 6 volt system. I have maintained the original 6 volt system running off a optima 6 volt battery and had problems with starting following a warm engine shut down. I changed the cables to custom larger diameter to eliminate that being a culprit. I still experienced the same issue. I then implemented a two optima battery configuration which I had found from research and the starting issue resolved itself immediately. Aside from having to charge the second battery when it drains too low my success with the optima batteries has not been favorable. I am now replacing for the third time a new battery just since last May that has gone bad. The one prior had failed but I don’t know how old that one was maybe a year to two years?
My concern is if the engine compartment is just too hot for the location of the batteries does this impact the longevity of the batteries? Aside from the obvious concern for explosion as noted here in this topic my desire is safety vs authenticity. Would this situation be improved by locating the battery or in my case batteries to the Trunk and removing the heat Factor all together?
I have read that others have experienced issues with Red top 6 volts recently but this seems out of the ordinary.

Thanks for any recommendations or comments.
Martin
 

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I'd go to NAPA and get an old school wet acid battery. Simple easy to diagnose, there is a reason they are still in demand.
NAPA people are very helpful with the older car owners, plus they have some very good aftermarket electrical stuff.
 
Well, installed new Duracell 6 volt 675 CCA Group 2 battery, heavy gauge cables, starter relay, 4 gauge ground from block to firewall, drove around for 90 minutes, stopped for takeout (15 min.), was little stubborn starting, battery seemed drained.

Just drove for 5 minutes, shut off, attempted to start again, battery was drained, will not start, clicking sound. Now I feel the battery isn’t getting charged while driving. Can’t even begin to communicate how unbelievably frustrating this is. Have zero confidence driving this car anywhere.

Since new battery install, my fuel gauge and horn stopped working as well.

I have new questions
1. Purchased automatic 6V battery tender, spoke with a T-Bird specialist, he said I should unhook the cables from battery before charging, since it’s positive ground. Is this standard practice?

2. Should I assume the generator is bad, since battery is weak after drive? Or is something drastically draining battery in short amount of time, while off?

3. Purchased a new battery cutoff switch, could someone tell me where to connect the orange cable?

4. I made my own ground wire, from block to firewall. Purchased 4 gauge wire from local store, and copper ends. Could this be part of the problem?

5. I also installed a new temp sending unit, I stripped back the wire and attached. My temp gauge is working, but don’t believe this is the correct part? Pic is attached.

6. Is 6V always going to be this difficult? Should I rewire to 12V?

7. “Martin P.” just asked if the battery should be relocated to the trunk? This is an excellent question. Though, if the battery caught fire again, there’s the risk of igniting the fuel tank.

I have a billion questions.

Thank youA86CA6EA-ADE2-4207-9616-B05D6CFABE8F.jpegC2465EAD-E74E-47D9-A887-D9CEDDED6ED4.jpeg742FA9BF-5E48-4BD0-9644-62FBCE29EB36.jpeg
 
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Sorry to hear of all these troubles! I’m not knowledgeable enough to help, but wanted to briefly weigh in regarding possibly moving the battery to the trunk:

I briefly considered doing this as well, but for a very different reason: the disc brake system I was considering a while ago apparently would have required relocating the battery to the trunk to make room for the new brake booster. Being quite new to classic cars at the time and having no real mechanical knowledge, I couldn’t quite articulate why that felt unsafe to me. At the time, my reasoning was just “there must be a reason why these cars were designed to have the battery in the engine compartment rather than the trunk.” Now - still not having much mechanical knowledge, but knowing a little bit more and especially having read stories like the one in this thread - I’m glad I went with my gut. Having the battery that close to (1) the fuel tank and (2) the flammable cloth trunk liner strikes me as a recipe for disaster in the event of a malfunction with the battery or the lengthy run of cables that would be needed to place the battery in the trunk. (I know there’s also gas in the carb near the battery in the engine compartment; but there’s at least less gas there than in the tank). That said, I really am still a novice and I know that folks more knowledgeable than me have done the battery relocation with no apparent problems, so I could be off base here.

For the original poster: I also wonder it’s time to take the car in to a professional specialist rather than continue to risk further issues. You seem much more knowledgeable than me; but at least for me, this really doesn’t seem like the kind of thing I’d want to do by trial and error myself.
 
‘willcarterdc”, I’m the original poster. Though seems like a good idea to relocate for heat reasons, I wouldn’t, due to gas tank.

Also, I prefer to work on my own car, as much as possible. I simply don’t want a mechanic working on my car, unless absolutely necessary.

Thanks
 
I farm out the messy stuff involving fluids. The shop I use has all the stuff as far as collecting that stuff. I don't want fluids on my floor even though I am capable of doing the work. I'm good at low voltage wiring and tune up and base mechanical issues.
I've got a driver that I keep as original as possible as enjoy keeping it as close to the original designers work. It worked then and still does 60+ years later only updating components where I have no choice. Mostly wear and tear stuff.
 
I have no personal experience with optima batteries,
but I have read that they are not as good as the older versions.
Do as Ward suggests and get a battery from Napa,

As for locating the battery in the truck, the cable you need for that length of a run would be very expensive, it needs to be a very large diameter cable for a 6 volt battery.

The extra wire on the battery terminal would be for your hot battery buse.

The temp sending unit must be matched to the indicator or it will be inaccurate at best.

You have many problems, but be patient and tackle one at a time.
 
Update:

Seems generator isn’t working, I pulled the negative battery cable, and the engine immediately shuts down. This makes sense to me, guess I’ll take it out and have it rebuilt (found local place).

Thanks for advice, to tackle one issue at a time, took deep breath today. Priority, is to get it running and not draining the battery.

Thank you!
 
photoguy said:
Update:

Seems generator isn’t working, I pulled the negative battery cable, and the engine immediately shuts down. This makes sense to me, guess I’ll take it out and have it rebuilt (found local place).

Thanks for advice, to tackle one issue at a time, took deep breath today. Priority, is to get it running and not draining the battery.

Thank you!
Click to expand...
I don't think it would keep running with no main ground. I don't think you have a generator problem, no harm in having it tested though. It's not like a small engine like an outboard motor or lawn mower with a magneto that doesn't need a battery to run.
 
If the engine was at idle when you pulled the cable, your engine speed would be too low for the generator to do its job. When the key is ON and the engine is off does the GEN light light come on? If not then that needs to be addressed.
Harbor Freight sells a volt meter for $5.00 that can be handy for troubleshooting and there is lots if info on Utube about how to test battery voltage.
I have a 55 still on 6V with an Optima battery. It has always started hot. What shape is your starter in? They are known to be problematic when they get old. Perhaps a new rebuild would help. 5 minutes of driving will NOT recharge your battery. Back when generators were common it was recommended that 20-30 minutes was needed to recharge your battery after a start.
 
Ward 57 said:
I don't think it would keep running with no main ground. I don't think you have a generator problem, no harm in having it tested though. It's not like a small engine like an outboard motor or lawn mower with a magneto that doesn't need a battery to run.
Click to expand...
That’s interesting, I just read a post where someone did this as a diagnosis, bummer! Earlier today I cleaned the generator connections, removed dirt and rust. Well, my battery definitely doesn‘t seem to be charging during drive, starts right up initially(after recharge), if I stop anywhere, battery is weak. It’s only $125 to have it rebuilt, probably needs it anyways. Every wire under the hood, is pretty brittle, should probably replace all.
 
Critterpainer said:
If the engine was at idle when you pulled the cable, your engine speed would be too low for the generator to do its job. When the key is ON and the engine is off does the GEN light light come on? If not then that needs to be addressed.
Harbor Freight sells a volt meter for $5.00 that can be handy for troubleshooting and there is lots if info on Utube about how to test battery voltage.
I have a 55 still on 6V with an Optima battery. It has always started hot. What shape is your starter in? They are known to be problematic when they get old. Perhaps a new rebuild would help. 5 minutes of driving will NOT recharge your battery. Back when generators were common it was recommended that 20-30 minutes was needed to recharge your battery after a start.
Click to expand...
I‘m doing long drives, about 90 minutes. I mentioned the 5 minute drive, because the battery totally drained after that one, I had gone on a long drive prior. Not saying it’s not the starter, but really seems like battery, maybe it’s both? After a drive, battery needs recharge, and it starts right up afterwards.

My Oil and Gen lights aren’t functioning, I was just in the garage checking the bulbs.

I have a newer, fancy volt meter, will start testing.

The good news, my battery isn’t catching fire!

Thank you!
 
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The charging system consists of the battery and cables, the alternator or generator, and an external voltage regulator. The function of the battery is to spin the starter motor to start the engine. Once that’s done, the alternator takes over, satisfying the car’s electrical demands and keeping the battery charged. The battery then acts primarily as a filter, keeping voltage spikes from damaging the car’s electronics. The voltage regulator rapidly switches the alternator in and out of the charging circuit to provide the car with the correct voltage. In 1955, the electrical system of the Thunderbird was 6 volt positive ground. In 1956, the Thunderbird electrical system was changed to 12 volt negative ground.

On the 12 volt system there are two important numbers to remember, they are 12.6 volts and 13.5 volts.

12.6 Volts: If you think your car has a 12 volt battery, it doesn’t. The 12 volt battery actually has six individual 2.1 volt cells (one under each fill cap). Thus, when fully charged, the battery should have a resting voltage of 12.6 volts. If with the engine off, the resting voltage is less than 12.6 volts, the battery is low and needs to be recharged. Of course, it begs the question of why the battery is low. It could be that the alternator isn’t working, or that the battery has reached the end of its useful life.

13.5 Volts: With the engine running, the alternator should output a charging voltage that’s about a volt higher than the resting voltage, or about 13.5 volts. The exact charging voltage may be as low as 13.2 volts or as high as 14.2 volts.

If your Thunderbird is a 1955, with a 6 volt, positive ground system, the resting voltage is 6.3 volts and the charging voltage should be about 7.1 volts. The exact charging voltage may be as low as 6.6 volts or as high as 7.1 volts.

Take a multi-meter and set it to measure DC voltage, then measure the voltage across the positive and negative battery terminals with the engine off. On a 12 volt system, a fully charged battery should read a resting voltage of 12.6 volts. After you start the car you should see a charging voltage of about a volt higher than resting voltage. If the reading doesn’t increase by about a volt or if it stays at the resting voltage, it means that the alternator isn’t recharging the battery. This could be because the alternator is defective, the regulator is defective, or the wiring between them has failed. In any case, if you drive the car, the battery will run down. If the battery runs down enough that the ignition stops firing, the engine will stall. It’s really important that you don’t simply jump-start a car with a dead battery without checking to see if the alternator is charging.

A basic charging system health test: Use a multi-meter to measure the resting and charging voltages as described above. Then, with the engine running, gradually increase the electrical load by turning on the headlights and the blower fan. Then increase the engine RPM to about 3500 as you watch the reading on the multi-meter. If the voltage stays about a volt higher than resting voltage, then the car’s charging system is functioning. But if the voltage drops or increases dramatically at any point, there’s a problem with the alternator or the voltage regulator.

doug7740
1955 Thunderbird Blue
 
The info Doug has presented is very good just divide the voltage numbers by 2 for a 6 volt system
The checks will be the same.
6.3 and 6.75
 
doug7740 said:
The charging system consists of the battery and cables, the alternator or generator, and an external voltage regulator. The function of the battery is to spin the starter motor to start the engine. Once that’s done, the alternator takes over, satisfying the car’s electrical demands and keeping the battery charged. The battery then acts primarily as a filter, keeping voltage spikes from damaging the car’s electronics. The voltage regulator rapidly switches the alternator in and out of the charging circuit to provide the car with the correct voltage. In 1955, the electrical system of the Thunderbird was 6 volt positive ground. In 1956, the Thunderbird electrical system was changed to 12 volt negative ground.

On the 12 volt system there are two important numbers to remember, they are 12.6 volts and 13.5 volts.

12.6 Volts: If you think your car has a 12 volt battery, it doesn’t. The 12 volt battery actually has six individual 2.1 volt cells (one under each fill cap). Thus, when fully charged, the battery should have a resting voltage of 12.6 volts. If with the engine off, the resting voltage is less than 12.6 volts, the battery is low and needs to be recharged. Of course, it begs the question of why the battery is low. It could be that the alternator isn’t working, or that the battery has reached the end of its useful life.

13.5 Volts: With the engine running, the alternator should output a charging voltage that’s about a volt higher than the resting voltage, or about 13.5 volts. The exact charging voltage may be as low as 13.2 volts or as high as 14.2 volts.

If your Thunderbird is a 1955, with a 6 volt, positive ground system, the resting voltage is 6.3 volts and the charging voltage should be about 7.1 volts. The exact charging voltage may be as low as 6.6 volts or as high as 7.1 volts.

Take a multi-meter and set it to measure DC voltage, then measure the voltage across the positive and negative battery terminals with the engine off. On a 12 volt system, a fully charged battery should read a resting voltage of 12.6 volts. After you start the car you should see a charging voltage of about a volt higher than resting voltage. If the reading doesn’t increase by about a volt or if it stays at the resting voltage, it means that the alternator isn’t recharging the battery. This could be because the alternator is defective, the regulator is defective, or the wiring between them has failed. In any case, if you drive the car, the battery will run down. If the battery runs down enough that the ignition stops firing, the engine will stall. It’s really important that you don’t simply jump-start a car with a dead battery without checking to see if the alternator is charging.

A basic charging system health test: Use a multi-meter to measure the resting and charging voltages as described above. Then, with the engine running, gradually increase the electrical load by turning on the headlights and the blower fan. Then increase the engine RPM to about 3500 as you watch the reading on the multi-meter. If the voltage stays about a volt higher than resting voltage, then the car’s charging system is functioning. But if the voltage drops or increases dramatically at any point, there’s a problem with the alternator or the voltage regulator.

doug7740
1955 Thunderbird Blue
Click to expand...
Wow! Love this forum! Will get on this later today, and will update. I’m getting such the education from here.

Thank you!!!!
 
doug7740 said:
The charging system consists of the battery and cables, the alternator or generator, and an external voltage regulator. The function of the battery is to spin the starter motor to start the engine. Once that’s done, the alternator takes over, satisfying the car’s electrical demands and keeping the battery charged. The battery then acts primarily as a filter, keeping voltage spikes from damaging the car’s electronics. The voltage regulator rapidly switches the alternator in and out of the charging circuit to provide the car with the correct voltage. In 1955, the electrical system of the Thunderbird was 6 volt positive ground. In 1956, the Thunderbird electrical system was changed to 12 volt negative ground.

On the 12 volt system there are two important numbers to remember, they are 12.6 volts and 13.5 volts.

12.6 Volts: If you think your car has a 12 volt battery, it doesn’t. The 12 volt battery actually has six individual 2.1 volt cells (one under each fill cap). Thus, when fully charged, the battery should have a resting voltage of 12.6 volts. If with the engine off, the resting voltage is less than 12.6 volts, the battery is low and needs to be recharged. Of course, it begs the question of why the battery is low. It could be that the alternator isn’t working, or that the battery has reached the end of its useful life.

13.5 Volts: With the engine running, the alternator should output a charging voltage that’s about a volt higher than the resting voltage, or about 13.5 volts. The exact charging voltage may be as low as 13.2 volts or as high as 14.2 volts.

If your Thunderbird is a 1955, with a 6 volt, positive ground system, the resting voltage is 6.3 volts and the charging voltage should be about 7.1 volts. The exact charging voltage may be as low as 6.6 volts or as high as 7.1 volts.

Take a multi-meter and set it to measure DC voltage, then measure the voltage across the positive and negative battery terminals with the engine off. On a 12 volt system, a fully charged battery should read a resting voltage of 12.6 volts. After you start the car you should see a charging voltage of about a volt higher than resting voltage. If the reading doesn’t increase by about a volt or if it stays at the resting voltage, it means that the alternator isn’t recharging the battery. This could be because the alternator is defective, the regulator is defective, or the wiring between them has failed. In any case, if you drive the car, the battery will run down. If the battery runs down enough that the ignition stops firing, the engine will stall. It’s really important that you don’t simply jump-start a car with a dead battery without checking to see if the alternator is charging.

A basic charging system health test: Use a multi-meter to measure the resting and charging voltages as described above. Then, with the engine running, gradually increase the electrical load by turning on the headlights and the blower fan. Then increase the engine RPM to about 3500 as you watch the reading on the multi-meter. If the voltage stays about a volt higher than resting voltage, then the car’s charging system is functioning. But if the voltage drops or increases dramatically at any point, there’s a problem with the alternator or the voltage regulator.

doug7740
1955 Thunderbird Blue
Click to expand...
Update:

Battery was still charging according to tender. Had been charging for 12 hours.

1. Resting voltage was 6.1v
2. 6.0v with engine started
3. 5.8v with lights and blower on
4. 6.0v @3500 rpm w/lights and blower

Seems charging system is working?

I actually ordered a starter this morning (not from usual retailer), before doing this test, since price was very reasonable. Not saying this is the issue.

Thank you!
 
photoguy said:
Update:

Battery was still charging according to tender. Had been charging for 12 hours.

1. Resting voltage was 6.1v
2. 6.0v with engine started
3. 5.8v with lights and blower on
4. 6.0v @3500 rpm w/lights and blower

Seems charging system is working?

I actually ordered a starter this morning (not from usual retailer), before doing this test, since price was very reasonable. Not saying this is the issue.

Thank you!
Click to expand...
It seems your generator is charging but the voltage regulator is out of adjustment. Yes the are adjustable and I believe it is covered in the shop manual.
 
Ward 57 said:
It seems your generator is charging but the voltage regulator is out of adjustment. Yes the are adjustable and I believe it is covered in the shop manual.
Click to expand...
The regulator is new. Is this common, it needs adjustment? Or is it defective?

Thanks
 
photoguy said:
Update:

Seems generator isn’t working, I pulled the negative battery cable, and the engine immediately shuts down. This makes sense to me, guess I’ll take it out and have it rebuilt (found local place).

Thanks for advice, to tackle one issue at a time, took deep breath today. Priority, is to get it running and not draining the battery.

Thank you!
Click to expand...
A rebuild wouldn't be out of line. The brushes do wear out over time and simple to replace. a rebuild shop will know how to dress the commutator which the brushes ride on. That too is in the shop manual but a shop would know how to do it properly.
 
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