Author Topic: 8 Volt  (Read 3209 times)

SteveG

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8 Volt
« on: December 30, 2013, 07:30:36 PM »
My Plymouth came with a 8 volt battery. I am deciding wether to switch to 6 volt.

Is anyone using an 8 volt system?

How is it working out?

SteveG

imoore

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Re: 8 Volt
« Reply #1 on: December 30, 2013, 09:09:23 PM »
Hey steve
Are u sure its an 8v battery not maximum charge rate of 8v.
A 6v battery has 3 cells. So if 8v should have 4 cells

Ian
1928 Q tourer (Holden bodied)
Several vintage stationary engine

chetbrz

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Re: 8 Volt
« Reply #2 on: December 30, 2013, 09:24:01 PM »
Steve,

I have not heard of an 8vdc car battery but of course that doesn't mean anything.  My knowledge of electronics tells me that this was probably the standard 6 vdc system and the 8 volt battery gave the starter a little more oomph!  Actually using 8 volts would give you brighter lights with less current draw and a better start.   I would think the generator was tweaked a little to produce an 8vdc charge.

How recent was it purchased.   Maybe it's a gell cell battery in your 6 volt system. Ian is correct about an 8 volt max charge rate.  If you measured the voltage while the car was running it might just be the generator producing the 8 vdc.  After all a 12 vdc system charges at around 13.5 volts.

My 2.5 cents,  Chet...
« Last Edit: December 30, 2013, 09:55:40 PM by chetbrz »
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Crazydave

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Re: 8 Volt
« Reply #3 on: December 30, 2013, 11:17:26 PM »
This is something we have been doing at the farm for years, with some of the older 6 volt system tractors. Chet hit it on the head, 6 volt system, 8 volt battery, better starts, brighter lights. No mods to the system. Drop it in and go. We buy them locally at fleet farm, and tractor supply has them as well

Here http://www.tractorsupply.com/en/store/exide-heavy-duty-farm-battery-8-1

imoore

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Re: 8 Volt
« Reply #4 on: December 30, 2013, 11:25:07 PM »
There u go. Never knew u could buy 8v batteries. But makes perfect sense.
1928 Q tourer (Holden bodied)
Several vintage stationary engine

chetbrz

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Re: 8 Volt
« Reply #5 on: December 31, 2013, 06:53:55 AM »

Dave thanks for clearing things up.  Tractor Supply is one of my favorite stores but I never noticed the 8 vdc battery, probably because I usually get my batteries from Napa.
 
Every day is a learning experience,  Cheers…
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Tinkeys

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Re: 8 Volt
« Reply #6 on: December 31, 2013, 06:07:17 PM »
Hi Guys !
         The 30U I had ! Was running a 8v battery  and I had no issues with it ! I also bought a 8v Alternater from the states and left original wiring to be able to put back 6v generator if needed, also bought 8v quartz halogen globes to fit directly into original headlight sockets ,, all can be put back to original specs .

Old Man

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Re: 8 Volt
« Reply #7 on: January 01, 2014, 10:16:42 AM »
A 6 volt system runs at 7.5 to 8.0 volts normally and always has. A 12 volt system runs at 14.8 volts. 6 and 12 volts are the nominal volts as the industry assumes 2 volts per cell on a sulphuric acid/water/lead plate battery. (Dry cells are less,1.5 volts, and nickel cadmium are more,2.25 per cell.) After one of our old cars has been running for a few minutes you can put a voltmeter on the 6 volt battery cable and it will read 7.5 to 8. on a good battery and a good generator at a fast idle. (You need a fast idle to close the reverse current cutout points and put the generator on the battery.) As the battery nears it's end of life, it will cease to take a full charge and start lingering around 6.5 volts or so. To test our old 6 volt systems you have to have a "fresh" battery that is known to charge to 8.O volts or so. Substituting a known good battery out of another antique is usually the quickest and cheapest way. A modern 12 volt battery also dies the same route and can be troubleshot the same way.
  Putting an 8 volt golf cart battery in is a common thing I understand,I've seen it before,but not neccessary. A good 6 volt battery that will allow the system to rise to it's correct 8.0 volts or so and a generator that will put it there, is all that's required. 6 and 12 volts are the nominal "shelf" terminal volts of a lead acid battery.For a 6 volt battery 4.0 volts or so is either a discharged battery or one that needs replacing. It should sit pretty well in the high 5.0s,even over 6.0, over a couple of weeks of storage after the last run. 12 volters should sit in the high 11.0s or even low 12.0s. I find too many 6 volt cars and trucks are haphazardly changed to 8.0 or even 12.0 volts when the problem is almost certainly a wiring problem. And an electrical fire is a possiblity. Or burned connections because of a voltage drop induced by corroded connections. This servicing system has worked for me for more that 30 years with no problems and I get an average of 10 years on my 6 volters,12 years on one of them.              
« Last Edit: January 01, 2014, 10:20:15 AM by Old Man »

SteveG

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Re: 8 Volt
« Reply #8 on: January 01, 2014, 09:37:11 PM »
Thanx for all the responses.

The battery is definitely an 8 Volt. (4 cells).

I noticed the contacts stay closed after I start the car and remain closed until I shut it down and then they open.

I understand that the contacts are supposed to remain open after starting until the engine is running fast enough to generate enough voltage to over come the battery voltage, then they open. I think that happens to prevent the generator from running backwards, like an electric motor. I don't know if my thinking is correct. I can't think of any other reason to have a relay.

The Owners Manual says the contacts close when the generator reaches a certain voltage.

Can you straighten out my thinking on this?

 Confused in Oregun.

SteveG

I have an 8 volt Battery Tender coming Friday to make sure I have a full charge on the battery.

Old Man

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Re: 8 Volt
« Reply #9 on: January 02, 2014, 09:16:14 AM »
Yes you're correct except your 2nd "open" in your post should be "closed",I think. You're correct in that the generator will try to "motor" except it's held tight by the fan belt and engine. This is the "reverse current" that's talked about. It's unusual for the cutout to close it's points immediately and not open them again until shutdown. Normally,on a correctly setup car, the generator needs some revs to produce enough current to close the cutout's points and be connected over onto the battery and onto the car's buss. If the revs drop below this point,even at idle, the points open,as the generator is not producing enough current to keep them closed, and the car runs on it's battery. Which as I mentioned will about 2 volts less than the generator output at speed. This causes the lights at night to dim slightly and then brighten up again as the revs come back ,say, as the car moves away from a stop. Even allowing the revs to drop to idle during a "slow" shift will cause the cutout points to cycle. Basically the generator becomes a chunk of copper wire connected to the battery at idle or at rest. This is why it must be disconnected to prevent the battery from just discharging through this "chunk of wire" to ground and flattening itself. You're right in your comment about the generator must having a voltage greater than the battery before the cutout will close,except it's really current that does it. As my professor used to tell us "Remember everything works because of "current injection" in electrical or electronics engineering and for no other reason."        
« Last Edit: January 03, 2014, 08:46:50 AM by Old Man »

SteveG

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Re: 8 Volt
« Reply #10 on: January 07, 2014, 02:48:47 PM »
Great information again. Thank you.

Here's an update. I received the 8 volt Battery Tender and charged to the correct level. The car fired right up.

The relay closes. It remains closed until I shut off the ignition. I have to drive it a while to see that the battery does not over charge.

I read that I may have to bend the contact spring to compensate for the 8 volt battery, but that remains to be seen.

If there are no further comments, or ideas from you, I'll keep you posted.

SteveG


Old Man

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Re: 8 Volt
« Reply #11 on: January 07, 2014, 04:16:23 PM »
There needs to be a "balance" between the generator output and the batteries' needs. Something is wrong here and my guess is the generator is overcharging the battery. If the cutout points never open then the generator/cutout combination is sensing that the battery always needs a charge i.e. current flowing "downhill" onto the car's buss and into the battery. My take on this is the battery is going to be "boiled" dry. There should be some give and take. There should be a point, at low revs, where the points open and the generator is released from the battery. The generator is always trying to pump up the battery to some "high" voltage that the battery posts can never reach. Otherwise equilibrium would be reached and the cutout would release the generator from the battery. I believe you're trying to overcharge your battery and this can bend plates and all sorts of ugly things. Don't forget the only reason the system stays at a nominal 6 or 12 volts is because of the battery itself. One of these old generators is quite capable of putting out 25 volts. Unload the generator by disconnecting the battery while the engine is running and you will blow every lightbulb that is turned "on" at that moment. And start to cook the ignition coil as well. A friend asked me to troubleshoot his motorcyle last Summer because he had no lights,directional signals the lot. I scratched my head for a few minutes and then after discovering there was no resistance coming back from any wire going to a light,I started pulling out bulbs. EVERYONE of the bike's bulbs were blown as he had switched on them all one after another to see if any of the lights worked. His battery was "open circuit" and with no regulator on this little 250 cc bike the bike's buss rose to 20 volts or so and blew every bulb. He had gotten the bike going with the kick starter. (The headlight alone cost him $75.)This will not happen with a vehicle that has a voltage regulator on it. But on our old stuff the "regulator" is the battery. Be careful out there.        
« Last Edit: January 07, 2014, 04:26:34 PM by Old Man »

28Q29U

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Re: 8 Volt
« Reply #12 on: January 07, 2014, 10:22:41 PM »
Great information again. Thank you.

Here's an update. I received the 8 volt Battery Tender and charged to the correct level. The car fired right up.

The relay closes. It remains closed until I shut off the ignition. I have to drive it a while to see that the battery does not over charge.

I read that I may have to bend the contact spring to compensate for the 8 volt battery, but that remains to be seen.

If there are no further comments, or ideas from you, I'll keep you posted.

SteveG

Steve,

In the Tech Section there was a document that explained how to adjust the third brush on the generator.  I repaired the links in the post and also provided it here for you.  Maybe this might help you with your current adjustment. 

http://www.1948plymouth.info/SupportPages/PNWR_Reprint.pdf
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Old Man

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Re: 8 Volt
« Reply #13 on: January 08, 2014, 10:27:02 AM »
Thanks Steve. The 3rd brush sets the "roof" of the current that the generator can deliver on a "flat" battery. This is to keep from overheating the windings in the generator. Most think the 3rd brush regulates the charging. It does not. If set to 20 amps on a flat battery,I recommend 15 amps, the generator can, and will, put out 20 amps IF the battery post voltage remains below the armature output voltage of the generator. The post voltage is really the controlling factor in all this. Once the battery's post voltage rises ABOVE the generator's, current stops flowing. This is the "set point" of the cutout. The system considers the battery to be charged. But you must have your cutout cycling or you will never know if you're overcharging your battery. Which is what I believe this gentleman is doing with his 8 volt setup. If I was there I could,and would, fix it very quickly but this "long distance" troubleshooting is difficult. The cutout needs to be put on a bench and connected to a varible power supply,which I have, and the point cycling set to the correct voltage by varying the voltage and adjusting the spring perch.                        
« Last Edit: January 08, 2014, 10:28:34 AM by Old Man »

chetbrz

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Re: 8 Volt
« Reply #14 on: January 08, 2014, 05:04:00 PM »
Hi Old Man,

I know it is eaiser to do then explain.  The information presented in this post has been very interesting.  I have just one question.  When you refer to the spring perch are you adjusting the tension of the spring to creat a different cutout based on the desired voltage which would equate to the strength of the cutout coils magnetic pull.

I am not sure if this statement makes sense and maybe I am not understanding the proceedure but I think I do and maybe I am not explaining it correctly.  What do you use as the cutout voltage and where are you measuring it ?

I am currently using an alternator but I have the old generator and would like to give it a go.  Sorry Steve for short stopping your post.

Tks Chet...
« Last Edit: January 08, 2014, 05:06:45 PM by chetbrz »
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