Go Back   The Ford Barn > General Discussion > Early V8 (1932-53)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 01-18-2022, 03:25 PM   #1
rayro39
Member
 
rayro39's Avatar
 
Join Date: May 2021
Posts: 38
Default 12v battery on 6v system?

I've had it with this weak 6v. I have the original 6v system on my 39 Ford Sedan. When it finally starts, it runs great.

Even with a new fully charged battery, the 6v barely turns the flywheel. Keep cranking over and over, then the solenoid starts smoking. I don't want to upgrade the whole system to 12v.

Has anyone used 12v battery to start 6v systems?

Still searching for timing and points adjustment instructions for 1939 Ford Sedan.
rayro39 is offline   Reply With Quote
Old 01-18-2022, 03:45 PM   #2
Tim Ayers
Senior Member
 
Join Date: May 2010
Location: NJ
Posts: 6,144
Default Re: 12v battery on 6v system?

I think the trick guys have done is use an 8V battery with a weak 6V system. I don't believe you can jump up to 12V battery with everything still being set up for 6V.

Have you checked all your grounds? I'd start there and see what happens.

Also, are you sure your distributor, timing, carburetor, fuel delivery, spark plug wires & plugs, etc. is up to snuff?

Hard starting could be caused by many other issues compounded into one big, hard start issue.

Here is a link to a 8V battery:

https://www.usbattery.com/products/8-volt-batteries/
Tim Ayers is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 01-18-2022, 03:58 PM   #3
petehoovie
Senior Member
 
petehoovie's Avatar
 
Join Date: May 2015
Posts: 7,933
Default Re: 12v battery on 6v system?

"Has anyone used 12v battery to start 6v systems?" - rayro39



Touch a 12 volt battery directly to the stater motor and ground. Make sure the transmission is in neutral and the ignition switch is ON....
__________________
The only thing nice about being imperfect is the joy it brings to others....

"Silver rings, your butt! Them's washers!"
"We shot our way out of that town for a dollar's worth of steel holes!" - from 'The Wild Bunch' - 1969

https://www.youtube.com/watch?v=7NReUd2_0u0

Last edited by petehoovie; 01-18-2022 at 04:29 PM.
petehoovie is online now   Reply With Quote
Old 01-18-2022, 04:09 PM   #4
rayro39
Member
 
rayro39's Avatar
 
Join Date: May 2021
Posts: 38
Default Re: 12v battery on 6v system?

It runs great once it cranks over. New fuel tank, lines, fuel pump, rebuilt carb. I'm going to convert to electric fuel pump.

I am focusing on timing and points. I've never done those on a flathead v8. This isn't the crab style distributor.
rayro39 is offline   Reply With Quote
Old 01-18-2022, 04:30 PM   #5
Lawson Cox
Senior Member
 
Lawson Cox's Avatar
 
Join Date: May 2010
Location: Above the gnat line in Georgia
Posts: 7,009
Default Re: 12v battery on 6v system?

Clean ALL connections to a SHINY clean, then go with a 6V Optima and your problems will go bye bye.
__________________
Life is like a roll of toilet paper. The closer to the end, the faster it goes.

It is better to be seen, than viewed.

"We sleep safe in our beds because rough men stand ready in the night to visit violence on those who would do us harm".
Lawson Cox is offline   Reply With Quote
Old 01-18-2022, 04:54 PM   #6
V8COOPMAN
Senior Member
 
V8COOPMAN's Avatar
 
Join Date: May 2010
Location: East Shore of LAKE HOUSTON
Posts: 11,106
Default Re: 12v battery on 6v system?

Sponsored Links (Register now to hide all advertisements)
Quote:
Originally Posted by rayro39 View Post
Even with a new fully charged battery, the 6v barely turns the flywheel. Keep cranking over and over, then the solenoid starts smoking. I don't want to upgrade the whole system to 12v.
Man, I WOULD FOLLOW THE SMOKE! It's entirely possible that the cables going to the two big lugs on the solenoid are either corroded, or loose. Take apart and wire brush/clean the cable connectors shiny bright. And one other possibility...6v battery cables are much heavier than 12v cables. If some previous owner (not knowing any better) walked into an auto parts store and merely asked for battery cables only by length, the 12v cables that he probably received are going to be way too small in diameter, and physically can't handle the current (amps) that it takes to crank that 6v starter. Good place to start.

Do yourself a HUGE favor and DO NOT use an 8v battery! DD
.
__________________
Click Links Below __


'35-'36 W/8BA & MECHANICAL FAN


T5 W/TORQUE TUBE
V8COOPMAN is offline   Reply With Quote
Old 01-18-2022, 04:56 PM   #7
19Fordy
Senior Member
 
19Fordy's Avatar
 
Join Date: May 2010
Location: Coral Springs FL
Posts: 10,879
Default Re: 12v battery on 6v system?

Not sure it's [pertinent but, I remember (years ago) when I jumped my 6V battery with a 12V battery and the 6V battery exploded. with a big BOOM. i had done it many times before but, the last time was the "boomer".
Read all of this:
https://forums.aaca.org/topic/297946...6v-with-a-12v/

Suggest you fix the problem the correct way. 8 V battery is a waste off $$$.

Check your 6V battery to make sure it's fully charged.
Try a new solenoid.
Is your starter in good condition.

Last edited by 19Fordy; 01-18-2022 at 06:08 PM.
19Fordy is offline   Reply With Quote
Old 01-18-2022, 05:05 PM   #8
aussie merc
Senior Member
 
aussie merc's Avatar
 
Join Date: Sep 2016
Location: sydney australia
Posts: 1,025
Default Re: 12v battery on 6v system?

just my 2 cents worth 6v should be fine so i would get a multi meter and find out what's going on [this is one of the gremlins with 6v any voltage drop reeks havoc] but having said that well maintained 6v systems work perfectly well
aussie merc is offline   Reply With Quote
Old 01-18-2022, 05:07 PM   #9
51woodie
Senior Member
 
51woodie's Avatar
 
Join Date: Apr 2018
Location: Chelmsford, ON Canada
Posts: 524
Default Re: 12v battery on 6v system?

There was, and still is, a lot go cars, American, British, German etc. running around the world with 6 volt systems. There were issues with the electrics when I got my stock '46 Coupe. Slow cranking, dim lights, poor charging, but the problems were all corrected by cleaning connections to ground, replacing the battery to solenoid cable with the proper size, and having my generator and regulator serviced by a shop knowledgeable in old style generators. It starts, runs and charges just like it was built. To me, it would seem that changing over to 12V would be more work and more expensive, that going through the circuits and putting them back in good order.
51woodie is offline   Reply With Quote
Old 01-18-2022, 05:09 PM   #10
V8COOPMAN
Senior Member
 
V8COOPMAN's Avatar
 
Join Date: May 2010
Location: East Shore of LAKE HOUSTON
Posts: 11,106
Default Re: 12v battery on 6v system?

As 19Fordy said: "Putting 12V into a 6V battery can blow up the 6V battery. The hydrogen sulfide gas
goes BOOM!"


Yeah, KABLOOEY!


__________________
Click Links Below __


'35-'36 W/8BA & MECHANICAL FAN


T5 W/TORQUE TUBE
V8COOPMAN is offline   Reply With Quote
Old 01-18-2022, 05:10 PM   #11
bobH
Senior Member
 
Join Date: May 2010
Location: so cal, placerville, vegas
Posts: 1,394
Default Re: 12v battery on 6v system?

Quote:
Originally Posted by rayro39 View Post
I've had it with this weak 6v. I have the original 6v system on my 39 Ford Sedan. When it finally starts, it runs great.

Even with a new fully charged battery, the 6v barely turns the flywheel. Keep cranking over and over, then the solenoid starts smoking. I don't want to upgrade the whole system to 12v.

Has anyone used 12v battery to start 6v systems?

Still searching for timing and points adjustment instructions for 1939 Ford Sedan.
In response to previous posts... whatever !
In response to your proposed idea, I like it. I've run my 47 for years that way, with only positive results.
Rumbleseat Paul posted his way to do this, and I simply copied what he did with his 34. Hopefully you can find his old Rumbleseat notes somewhere.
Briefly, I ran my 47 on 6 volts. The 12 Volt battery was separate, and a 'total-loss' affair. It would need a recharge every few months - no 12V charging done with the car. (Small 12V battery, 80 Fairmont, I think) The starter was the ONLY thing that ever saw 12V. The rest of the car ONLY saw the original 6V. Like Rumbleseat, I would always attempt to start on 6V. If there was no quick response, then I would hit the 12V button. It never failed. Thanks to Paul for a great idea.

(Should probably add... On my 34, I did the total assembly of that car. As such, I handled each and every wiring connection. So, it was all fresh and clean, with proper size wires. That car functions fine, as it should, on 6V. The only issues I had, were (1) a good battery, and (2) a good starter - took two tries to get a good starter. So, my point being, like others have posted, should be able to make your 39 work good, if you wade through all the subtle troublesome areas. My first guess - if wiring issues are good, then I'm thinking, starter - because you say 'barely turns the flywheel'.)

(Something to think about, because I almost never see it mentioned... How about that starter solenoid (switch)? It has to carry to full starting current, perhaps 150-200 amps. How old is that thing? Original 1939? Have you measured the voltage drop across it? I only mention this because I have a 96 Ford with 300K miles on it. I recently had starting issues, and found that the switch was 'tired', and had developed a voltage drop across it. Check your voltage drops - should be able to see almost cranking voltage at the starter, same as cranking voltage measured at the battery. ie, no lost voltage from battery, to starter.)

Last edited by bobH; 01-18-2022 at 06:13 PM.
bobH is offline   Reply With Quote
Old 01-18-2022, 05:27 PM   #12
Charlie ny
BANNED
 
Join Date: May 2010
Posts: 3,019
Default Re: 12v battery on 6v system?

ixnay on the 8v.....I depend on my test motor which languishes in my unheated barn
12mo per year. I use a Walmart 6v battery and big fat cables....minus 6 last week end
and she fired right up both days just ask my neighbors.
Charlie ny
Charlie ny is offline   Reply With Quote
Old 01-18-2022, 05:32 PM   #13
FlatheadTed
Senior Member
 
FlatheadTed's Avatar
 
Join Date: May 2010
Location: Auckland
Posts: 4,691
Send a message via AIM to FlatheadTed
Default Re: 12v battery on 6v system?

On a 39 Ford you hook one jump cable battery to the side of the solenoid , the one that goes down to the starter , the other cable goes battery to head bolt ,with key on just touch this to throw the starter ,,battery can be wired x to neg or neg positive ,Mines a variation of Pete Hoovys
__________________
http://www.flatheadted.com


Flathead Ted brake Floaters ,

Last edited by FlatheadTed; 01-18-2022 at 09:47 PM.
FlatheadTed is offline   Reply With Quote
Old 01-18-2022, 06:33 PM   #14
Tim Ayers
Senior Member
 
Join Date: May 2010
Location: NJ
Posts: 6,144
Default Re: 12v battery on 6v system?

Plenty of farmers growing up used an 8v in their 6v tractors. Certainly worked then. I still say find the issue. Re-reading your post, you could install a 12v just for starting, but that sounds a lot more complicated than finding the issue.
Tim Ayers is offline   Reply With Quote
Old 01-18-2022, 06:55 PM   #15
MAG
Senior Member
 
MAG's Avatar
 
Join Date: May 2010
Location: Austin, Texas
Posts: 925
Default Re: 12v battery on 6v system?

X2 on post 12. If you do it make sure you have plenty of spare bulbs because you will need them. Most of the old tractors 6volt did not have working lights.
__________________
I noticed the harder I work the luckier I get!
MAG is offline   Reply With Quote
Old 01-18-2022, 07:34 PM   #16
1939mars
Senior Member
 
1939mars's Avatar
 
Join Date: Jun 2011
Location: Altadena, CA
Posts: 127
Default Re: 12v battery on 6v system?

When I bought my second '39 pickup it had an 8V battery in it. I cleaned connections up as stated in other posts, went through the ignition system and put in a 6V optima. With 8V and dirty/old cables and connections it started quite slowly but now starts immediately. I have been pleasantly surprised given the trouble I have heard people have with 6V - don't give up on it!
1939mars is offline   Reply With Quote
Old 01-18-2022, 09:52 PM   #17
FlatheadTed
Senior Member
 
FlatheadTed's Avatar
 
Join Date: May 2010
Location: Auckland
Posts: 4,691
Send a message via AIM to FlatheadTed
Default Re: 12v battery on 6v system?

To have a 12 volt just for starting wire in another solenoid on the starter side then to the 12 V ,and a ground ,this would be a total loss ,you could add a Alternator on the back wheel like Lawrie does on his Caravan ,
__________________
http://www.flatheadted.com


Flathead Ted brake Floaters ,
FlatheadTed is offline   Reply With Quote
Old 01-18-2022, 10:50 PM   #18
mh_merc
Junior Member
 
mh_merc's Avatar
 
Join Date: Dec 2017
Posts: 29
Default Re: 12v battery on 6v system?

There used to be a "6-12" battery - two 6V units switched by a solenoid so that you had 12V to start and went back to 6V to run. It solved the weak cranking problem when my old '42 wagon's flathead was hot.
mh_merc is offline   Reply With Quote
Old 01-18-2022, 11:06 PM   #19
RalphG
Senior Member
 
RalphG's Avatar
 
Join Date: Sep 2014
Location: Sask. Canada
Posts: 2,419
Default Re: 12v battery on 6v system?

Theres got to be something wrong if that 39 cranks slowly on six volts. My 39 Deluxe is all stock and that starter spins the flathead plenty fast on six volts. Faster than the 52 Merc. I've used 12 volts to start the Merc but straight to the solenoid, by-passing the rest of the car's electrical system.
RalphG is offline   Reply With Quote
Old 01-18-2022, 11:08 PM   #20
Brian
Senior Member
 
Brian's Avatar
 
Join Date: May 2010
Location: Masterton, New Zealand
Posts: 3,816
Default Re: 12v battery on 6v system?

as your vehicle runs well once running, the problem is in the starter motor circuit. Could be any or all of the following; starter needs rebuild, insufficiently sized cables, bad ground connection[s] from starter to block, block to chassis, chassis to battery, dirty connections anywhere else [bat to solenoid, solenoid to starter, even within the solenoid]....
The solenoid smoking would be a good place to start, there is obviously high resistance; lotsa heat there.
__________________
Unfortunately, two half wits don't make a whole wit!
Brian is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 01:27 AM.