How many Volts at the battery if generator set correct?

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Model T Ford Forum: Forum 2016: How many Volts at the battery if generator set correct?
Top of pagePrevious messageNext messageBottom of page Link to this message  By Kevin Weeds on Saturday, January 02, 2016 - 10:01 pm:

My 23 Depot Hack doesn't run smooth once over 20 mph on Mag but does when switched to batt hence all comments below are when key switched to battery.

I've fitted a new cutout to my Genny and its working again. I also fitted a auto reset 20 amp fuse as a trial close to the Genny.
The dash amp gauge shows 10amp when on the open road with the lights turned off, just below zero if the lights are on. At low idle amp gauge reads just above zero.
On the actual battery terminals it reads 6.97v when motor turned off, about 6.85v when idling and about 8.15v at fast idle. If I turn the lights on the battery voltage drops to 6.85v at fast idle.

The question is if I don't use the lights is 8.15v too much over time for my 6v battery on a longer run? If it is I could simply turn the lights on every so often to take some out of the battery or at least zero the charge into the battery for a bit.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Saturday, January 02, 2016 - 10:09 pm:

At ten amps your generator won't last long. I wonder what kind of headlight bulbs are pulling. 5 amps each?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rod Barrett - Anderson, IN on Saturday, January 02, 2016 - 11:08 pm:

I highly recommed the Fun Projects voltage regulator. It will solve all of these issues.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kevin Weeds on Saturday, January 02, 2016 - 11:54 pm:

Royce it doesn't sound right I agree.
Rod I have considered this option, thanks.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tony Bowker, Ramona, CA on Sunday, January 03, 2016 - 01:46 am:

Royce, 5 amps at 6 volts (nominal) is 48 watts which is typical of the rating of the headlamp from T vendors. Some are 32watts, others are 48 watts....
Back to the original thread, am I suppose to believe the battery voltage is lower when the battery is not being charged than when charged at 10 amps. If that is really happening, something is seriously amiss.....
I think there are some typos!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Sunday, January 03, 2016 - 06:58 am:

Perhaps it is just my simplistic view and lack of understanding of electricity, but wouldn't 5 amps at 6 volts be 30 watts?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Sunday, January 03, 2016 - 10:36 am:

Yes and 10 amps at 8.15 volts is 81.5 watts.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tony Bowker, Ramona, CA on Sunday, January 03, 2016 - 10:51 am:

Hal, I had a senior moment, the 32 watt bulb would need 5.5 amps and the 48 watt 8 amps. Kevin probably has 32 watt bulbs. Sorry about that.....


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kevin Weeds on Sunday, January 03, 2016 - 02:23 pm:

Tony it wasn't a typo. The voltage on the battery terminals is 6.97v when the motor is not running and at fast idle its 8.15v due to the fact the generator is now providing charge to the battery, does that sound like something is seriously amiss to you?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tony Bowker, Ramona, CA on Sunday, January 03, 2016 - 02:45 pm:

That seems a little high, but if that what it is, so be it. If the generator is putting out 10 amps into a six volt battery, at a fast idle, then the generator should last forever. I am still concerned at more than 2.3 volts at each cell.... What is the voltage at the cutout output? It should be a little higher than what you measure at the battery. The reduction from 6.97 to 6.85 is due to the current taken by the coils. I still think 2.3 volts per cell is a concern...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Sunday, January 03, 2016 - 03:00 pm:

Should be 6.9 to 7.3 volts. You have a high risk for battery failure. With no magneto it will be trailer time.


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Sullivan on Sunday, January 03, 2016 - 05:09 pm:

You have a high risk of generator failure if that fuse blows or malfunctions like, as in, guaranteed. Dave in Bellingham, WA


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kevin Weeds on Sunday, January 03, 2016 - 08:08 pm:

I retested it today and it was the same, I also tested it with a analog volt meter as I know some of you dont like digi with the same result. Analog got different voltages but the ratio was the same. I thought I would add these to the thread so I came inside and got a pen & Paper and when I retested it again they have all changed & it seems better now?
Readings all at battery terminal -

Engine off - 6.25 v
low idle (Key on Batt) - 6.4 v............(6 amp)
Fast Idle (on Batt) - 6.6 v ...........(9 amp)
Fast Idle (On Batt) Lights on - 6.6 v ....(-1 amp)
Fast idle, lights off on "Mag" - 6.8v

Went for a 30 min drive & rechecked, same.

I will monitor each day until I'm confident the fault hasn't returned.

Royce it still runs on mag just splutters a bit so I can make it home if I have a failure.

Tony yes the reading is higher at the cutout than the battery.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tony Bowker, Ramona, CA on Monday, January 04, 2016 - 01:31 am:

Those results look much more typical of a working system. Most digital voltmeters respond to the electrical spikes that come out of the generator, yielding in-accurate results. The best to use on a Model Tm when the engine is running, is a really good analog meter with a parallax mirror, like an Simpson.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem - SE Michigan on Monday, January 04, 2016 - 10:48 am:

Royce,

Each of my 4 T's draw 10 amps for the headlights. I set the generators to deliver 8 - 10 amps and have never had a generator failure due to it. My batteries last at least 5 years.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Monday, January 04, 2016 - 12:03 pm:

Jerry,

If the voltages in his last post are accurate then I agree it is not too bad, although also not too good.

The amps are higher than what I get in my '23, but then I have all new everything (wiring, battery, cables, Ron Patterson generator overhaul) and a Fun Projects VR. I never see more than 5 amps. It gets close to zero amps driving on MAG when the battery is fully charged. Lights on at night it does not go much negative, maybe an amp discharge.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kevin Weeds on Tuesday, January 05, 2016 - 12:52 am:

I forgot to turn the battery isolator off yesterday and today the battery was flat, never done that before?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erik Barrett in Auburn Ca. on Tuesday, January 05, 2016 - 02:30 am:

If the battery goes flat overnight with the isolator turned on, you have a draw on the battery that must be corrected. Perhaps something left turned on, or a stuck generator cutout, maybe a brake light switch sticking if you have one on the car.
I like the Fun Projects regulator. It works perfectly, assuming the instructions are followed so that the generator is in its comfort zone as to output.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kevin Weeds on Tuesday, January 05, 2016 - 03:42 am:

The Genny cut out is brand new, maybe a fun projects unit will fix the issue in the meantime isolator every time from here on.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Tuesday, January 05, 2016 - 09:25 am:

Kevin:

The "isolator" (I assume you mean a battery disconnect switch) is probably what is causing the difference in voltage readings since it isn't possible for them to deliver a low enough connection resistance to be reliable. Battery disconnect switches cause more problems than any other "addition" to the electrical system. Model T's were not vehicles known to burst into flames and a disconnect switch is a poor substitute for finding and fixing any sort or parasitic drain on the battery. If they were a good idea I would have one on my own T but since T's are not known to burst into flames but modern cars most certainly have a track record of doing that - to me it would be far more prudent to add a disconnect switch to my modern car than to the T parked next to it. The T is an order of magnitude simpler in its electrical system and the entire system can be inspected in about 5 minutes. A fuse is something I do recommend and do trust but if there is something on fire I sure would not recommend getting anywhere near the battery. Almost every day I talk to someone who is having problems that turn out to be caused by "disconnect" switches installed for only one reason - somebody told the buyer that his car is unsafe without it. Then so is your modern car and way worse.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Willard Revaz on Tuesday, January 05, 2016 - 10:27 am:

Tony and All, perhaps we are confusing a C. P. (candlepower) Rating of bulbs with an Ampere rating here. Vendors sell T headlight bulbs with a 21-6 or 50-32 C. P. Rating with no mention of current (Amps). I just tested a vintage 36 C. P. bulb here and it drew 3 Amps at 6 volts. (18 watts). 48 watt bulbs must be in the halogen or sealed beam category or am I missing something here..


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Tuesday, January 05, 2016 - 10:40 am:

Willy he is also running the coils on battery, which ought to pull about 1.5 amps.

I suspect John is correct that the battery disconnect switch is causing a voltage drop to the battery. Kevin needs to evaluate the wiring and find out where the voltage and current problems stem from. Fix those problems and ditch the switch.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kevin Weeds on Tuesday, January 05, 2016 - 02:16 pm:

I get your points on the isolator but up until yesterday it didn't matter if it was left on or off it never effected the battery so I guess now that I have a working Genny cut out the battery drain has returned (if it was there to start with 8 years ago when the Hack was last used). Perhaps that is why the previous (now deceased) owner fitted it?
How do I go about finding the drain or cause?
Thanks Guys


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Tuesday, January 05, 2016 - 02:41 pm:

There are many ways to troubleshoot a battery drain. Simplest to me is to remove the battery and measure the resistance from the + to ground. Leave the meter hooked up and in sight. Then start disconnecting things until the resistance goes open.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tony Bowker, Ramona, CA on Tuesday, January 05, 2016 - 03:54 pm:

Until the advent of modern bulbs such as LEDs etc., most bulbs were 1CP for each watt. I didn't know that they had made tungsten filaments 100% more efficient!


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