1963 Battery Problems

TheCrouchEndTiger

1963 Ford Thunderbird Convertible
Joined
Aug 11, 2018
Thunderbird Year
1963
Hi All

I have a 63 convertible and gone through several batteries. The last one I used was a Bosch S4 80Ah, CCA 740A. The car doesn't get used a lot, just on sunny days. If the car sits in the garage for a while (4 weeks) I find that it is hard to start (am thinking of installing an electric fuel pump near the tank). As it's a convertible it is using more power to drive the roof mechanism also. I was wondering if the specification of the battery I'm using is too low due to extra cranking for cold starts and roof operation? Any one have any ideas as I'm about to replace the battery? The car has had a new coil and mechanical fuel pump fitted. TBH, I'm not sure if its a combination of things:

Higher spec battery
Electric fuel pump
Maybe alternator?

Any advice would be much appreciated. By the way I'm in the UK so the batteries available here maybe different to the US.

Many thanks

Will

TB Battery.PNG
 
Last edited by a moderator:

apines

Active Member
Joined
Sep 13, 2020
Thunderbird Year
1955
Lead acid batteries self-discharge. This means even if you don't have any parasitic loads it will slowly lose its charge. A battery tender would counter that. However, four weeks isn't really that long for a car battery so I'm skeptical that it's only from self-discharge. Try connecting a multimeter in series with the battery when the car is off to see how much current it drawn. It should be very close to zero. If not, try pulling fuses until the current stops. That will help you isolate which circuit is causing the drain.

After it's been sitting, is it hard to start because it's not cranking adequately (low battery) or it takes a while for fuel to flow?
 
Joined
Aug 14, 2019
Thunderbird Year
1957
Sounds like you have a good sized battery. First thing, I would check if you have any residual current draw. Just pull the negative cable and put an amp meter between the cable and post. You should see nothing. If you do there is a draw somewhere. Could even be the clock or something simple. At least buy a battery tender to keep it up or even buy a quality battery charger. The new ones have great circuits compensating for temp up to 60+ amps to start a dead battery and even an equalizing program to condition your battery and also can act as a trickle charge.
In my opinion it's better to let a cold engine crank to build up oil pressure before it fires off.
 
Last edited:

knuckle47

Active Member
Joined
Nov 12, 2021
Thunderbird Year
1956
I noticed this with my ‘56. The battery is fairly new but in 2 weeks was slow cranking. Not that the wiring behind the dash couldn’t be contributing to some odd issues but… I added a battery maintainer ( not a trickle charger) and when it sits now for 2 or 3 weeks, it spins like my diesel pickup…lightening fast. This has contributed the much better starting and the fuel shows up at the carb in less than a few cranks while oil pressure is building


They have modular connectors so you may leave the wires permanently attached to the battery cables… extra of course
 

sre

Active Member
Joined
Jan 9, 2020
Thunderbird Year
1957
Hi All

I have a 63 convertible and gone through several batteries. The last one I used was a Bosch S4 80Ah, CCA 740A. The car doesn't get used a lot, just on sunny days. If the car sits in the garage for a while (4 weeks) I find that it is hard to start (am thinking of installing an electric fuel pump near the tank). As it's a convertible it is using more power to drive the roof mechanism also. I was wondering if the specification of the battery I'm using is too low due to extra cranking for cold starts and roof operation? Any one have any ideas as I'm about to replace the battery? The car has had a new coil and mechanical fuel pump fitted. TBH, I'm not sure if its a combination of things:

Higher spec battery
Electric fuel pump
Maybe alternator?

Any advice would be much appreciated. By the way I'm in the UK so the batteries available here maybe different to the US.

Many thanks

Will

View attachment 20973
Make sure EVERYTHING is turned off , remove the bulb in the hood if it has one. Disconnect the negative terminal on the battery, remove, touch battery cable to terminal. If it sparks something is drawing current.
 
Joined
Feb 9, 2019
Thunderbird Year
2002
Look, I've owned many classics and sometimes they sit for weeks, a battery cutoff switch is the first thing you want to install - specifically the "knife-blade" switches on the negative termianl (avoid the Chinwanese-ium round knob type):


They also make them where the "blade" moves sideways if that's a better fit. Any of the modern "smart" tenders will work just make sure it has a "maintenance" mode that will keep the surface charge on the battery.


740 CCA is plenty of power for your car.

After a couple of weeks, yes the fuel in your fuel bowls will evaporate and it will take some cranking to start the car and a "booster" electric pump can mitigate that but it adds complication and its own set of problems. If the car starts after extended sitting in 5-7 seconds that's normal. When I rebuild carbs I don't prefill the bowls with any fuel and install them bone dry, on a car with a properly operating fuel system they will start the car in that 5-7 seconds and usually on the lower end of that range.

Finally, make sure your choke is operating properly.
 
Last edited:

TheCrouchEndTiger

1963 Ford Thunderbird Convertible
Joined
Aug 11, 2018
Thunderbird Year
1963
Lead acid batteries self-discharge. This means even if you don't have any parasitic loads it will slowly lose its charge. A battery tender would counter that. However, four weeks isn't really that long for a car battery so I'm skeptical that it's only from self-discharge. Try connecting a multimeter in series with the battery when the car is off to see how much current it drawn. It should be very close to zero. If not, try pulling fuses until the current stops. That will help you isolate which circuit is causing the drain.

After it's been sitting, is it hard to start because it's not cranking adequately (low battery) or it takes a while for fuel to flow?
Thanks for the response and suggestions. I replaced the battery with a slightly bigger one, designed for more electricals and stop/start. Took the advice of getting a mulitmeter, which several others have also suggested, and now I test the battery before and after use to see if there is a big difference. After a run the battery normally reads approx 13.20 - 13.30 depending on the length of the drive. If I go back after 2 weeks, I notice the charge around 12.90. Have tested this 6 times now, and same every time. I also disconnect the battery after every drive to eliminate any draw or parasitic loads. Not sure why it drops, could be because of the difference in engine bay temperature after drives?

After it has been sitting, it cranks ok, but takes a long time to start, and always struggle to get it to fire easily. I'm pretty sure this is a fuel problem. Either evaporation or fuel slowly flowing back to the tank. If I use some quick starter fluid, it does start much quicker, but this is difficult to do on your own.
 

TheCrouchEndTiger

1963 Ford Thunderbird Convertible
Joined
Aug 11, 2018
Thunderbird Year
1963
Look, I've owned many classics and sometimes they sit for weeks, a battery cutoff switch is the first thing you want to install - specifically the "knife-blade" switches on the negative termianl (avoid the Chinwanese-ium round knob type):


They also make them where the "blade" moves sideways if that's a better fit. Any of the modern "smart" tenders will work just make sure it has a "maintenance" mode that will keep the surface charge on the battery.


740 CCA is plenty of power for your car.

After a couple of weeks, yes the fuel in your fuel bowls will evaporate and it will take some cranking to start the car and a "booster" electric pump can mitigate that but it adds complication and its own set of problems. If the car starts after extended sitting in 5-7 seconds that's normal. When I rebuild carbs I don't prefill the bowls with any fuel and install them bone dry, on a car with a properly operating fuel system they will start the car in that 5-7 seconds and usually on the lower end of that range.

Finally, make sure your choke is operating properly.
Hi Frankie, thanks for the response and suggestions. Have been disconnecting the battery manually after every drive and also tested the charge before and after use which seems fairly consistent. The cut off switch you suggested makes a lot of sense so will look into that. Regarding the the difficulties in starting after several weeks, I do think this is related to fuel getting to the carbs. If I use some quick start fluid, it normally fire much quicker. Must admit I've not timed if it takes more than 7 seconds, but will the next time I take her out.
 
Joined
Aug 14, 2019
Thunderbird Year
1957
Thanks for the response and suggestions. I replaced the battery with a slightly bigger one, designed for more electricals and stop/start. Took the advice of getting a mulitmeter, which several others have also suggested, and now I test the battery before and after use to see if there is a big difference. After a run the battery normally reads approx 13.20 - 13.30 depending on the length of the drive. If I go back after 2 weeks, I notice the charge around 12.90. Have tested this 6 times now, and same every time. I also disconnect the battery after every drive to eliminate any draw or parasitic loads. Not sure why it drops, could be because of the difference in engine bay temperature after drives?

After it has been sitting, it cranks ok, but takes a long time to start, and always struggle to get it to fire easily. I'm pretty sure this is a fuel problem. Either evaporation or fuel slowly flowing back to the tank. If I use some quick starter fluid, it does start much quicker, but this is difficult to do on your own.
Batteries are often mis-understood. 12.9 V is a fully charged battery resting voltage is usually around 12.3 - 12.5V. After driving there is excess surface charge giving you the 13+V that will dissipate after sitting.
Taking a bit to start is actually a good thing after sitting. Most of the oil film will have drained off lessening the cushion. Cranking until the oil light goes off pre-pumps the oil pressure before the stress of firing off, preventing premature wear & tear.
 

TheCrouchEndTiger

1963 Ford Thunderbird Convertible
Joined
Aug 11, 2018
Thunderbird Year
1963
Batteries are often mis-understood. 12.9 V is a fully charged battery resting voltage is usually around 12.3 - 12.5V. After driving there is excess surface charge giving you the 13+V that will dissipate after sitting.
Taking a bit to start is actually a good thing after sitting. Most of the oil film will have drained off lessening the cushion. Cranking until the oil light goes off pre-pumps the oil pressure before the stress of firing off, preventing premature wear & tear.
Thanks for that extra information, very useful. I think I was a bit paranoid with the battery issue that I started to think the long cranks were draining the battery, which has happened in the past on the old battery, but that could be the old battery was already losing charge. Will monitor the new one more closely to ensure it is always close to 12.9V.

Quick question, I also checked the voltage when it was in idle and it was registering 15.35. Is this normal or is it too high. Wondering if this might have caused the old batteries to fail so quickly? Thanks
 

jimntempe

Active Member
Joined
Apr 2, 2021
Thunderbird Year
1957
Hi All

I have a 63 convertible and gone through several batteries. The last one I used was a Bosch S4 80Ah, CCA 740A. The car doesn't get used a lot, just on sunny days. If the car sits in the garage for a while (4 weeks) I find that it is hard to start (am thinking of installing an electric fuel pump near the tank). As it's a convertible it is using more power to drive the roof mechanism also. I was wondering if the specification of the battery I'm using is too low due to extra cranking for cold starts and roof operation? Any one have any ideas as I'm about to replace the battery? The car has had a new coil and mechanical fuel pump fitted. TBH, I'm not sure if its a combination of things:

Higher spec battery
Electric fuel pump
Maybe alternator?

Any advice would be much appreciated. By the way I'm in the UK so the batteries available here maybe different to the US.

Many thanks

Will

View attachment 20973
If you don't drive it often there's a good chance you simply are never getting the battery fully charged. It could seem ok while you are driving it but might only be at 70% charge, then it sits for 4 weeks and drops down from there. As has been suggested you should check to see if there is any current draw at all on the battery when everything supposedly is off. Even a few milliamps adds up over a month. There should be zero parasitic draw on these cars unless you have added something modern like a radio which draws some power all the time to keep it's memory alive. A GOOD brand battery tender can't hurt. The Battery Tender brand comes with needed cables to make it easy to connect and disconnect the tender. I've had good luck with them.
 

74 Harley

Active Member
Joined
Jul 8, 2020
Thunderbird Year
1962
15.35 volts is in the high end of normal, you are probably checking after starting when the battery has depleted some and the generator is trying to catch up. Test your voltage after about a half hour drive. You will have fun and that will give the battery time to recharge.
 
Joined
Feb 9, 2019
Thunderbird Year
2002
My experience is that 15.35 volts is defintiely too high...13.8v to 14.2v is usually a normal "fast idle" charging voltage...
As initially suggested by @biddle above a good "smart" battery tender is a way to deal with the car sitting for extended times.
I have three cars, a boat and a jet ski that are on tenders nearly full time and there is NO downside to them.
 
Last edited by a moderator:

TheCrouchEndTiger

1963 Ford Thunderbird Convertible
Joined
Aug 11, 2018
Thunderbird Year
1963
Just want to say a big thank you for everyone who contributed to this thread. Many have suggested get a battery tender and also cut off switch for the battery terminal. Both great ideas. Batteries seem simple but just to share my findings for others who might come across the same issues.

As @Ward 57 mentioned a fully charged battery is normally around 12.9V which is what I am seeing before taking the car out for a run
@74 Harley / @Frankie the Fink mentioned that 15.35V when vehicle is in idle is high, but after a long run this comes down to 13.65V after a long run, so testing at idle can have varying readings depending on how charged the battery is. So best to test after a long run as suggested by @74 Harley
@Ward 57 mentioned that after long runs the battery reading may read 13V+ with excess surface charge, but this will dissipate once cooled down, which is exactly what I was getting.

Have tested a number of times now and it's fairly consistent with what everyone is saying, even after 3 weeks without use it is still the same.

Thanks again!
Will
 
Top