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Ford Tractors Discussion Forum

Charging issue on my 641

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02-14-2020 05:06:12

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This 641 is a six volt system, positive ground, the problem is: it doesn't seem to be charging, needle stays at zero. Turn the lights on and it jumps in the positive area.

Had been operating normally up until about a month ago.

Any ideas?

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Tim PloughNman Daley

02-14-2020 07:19:34

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 Re: Charging issue on my 641 in reply to shoprat, 02-14-2020 05:06:12  
How’s the battery? Fully charged and does it meets specific gravity criteria on a bench test machine? Is the generator good –can motor test yourself or bring to your local starter shop with the battery and Voltage Regulator for testing. Did the AMMETER show a "+" charge when running before this happened? When running, AMMETER will show a "+" charge and when light switch is ‘ON’ will show a reduced, "0", or "-" charge. If AMMETER displays a NEG/- reading when running with lights on, chances are the gauge has been wired in reverse so simply switch the wire flow. If OEM LOOP/INDUCTION gauge, feed wire thru loop in reverse. If aftermarket 2-Terminal style, just switch the two terminals over. A NO charge at all on gauge running the tractor normally could be a bad gauge. Before you go out and buy a new one, or any other part, go thru wiring and components. Take lights out of the equation first to troubleshoot. Lights were not factory issued on 600’s and earlier. Do you have the Clymer/ I&T FO-20 manual?


Tim Daley(MI)

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02-14-2020 09:22:35

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 Re: Charging issue on my 641 in reply to Tim PloughNman Daley, 02-14-2020 07:19:34  
Thanks, Tim. The system had been operating properly, nothing has been changed. Before, she would show a charge after starting, turning on the lights would lower the charge but still stayed in the positive.

Going to do some testing. I'll post the results.

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Tim PloughNman Daley

02-15-2020 07:26:22

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 Re: Charging issue on my 641 in reply to shoprat, 02-14-2020 09:22:35  
The battery is the 'heart' of the electrical system. A weak or dead battery is often the culprit in non-starting tractors/vehicles. The constant discharging and recharging of a battery will deplete its life span quickly. Bargain house units have a reputation of only giving 2 years or less of life so invest in a good brand (INTERSTATE, DEKA, DURACELL/East Penn) GP1 6V AG or GP25 or GP 35 12V battery. The best investment you can make to ensure a long battery lifespan is to buy and use a float charger. NOTE: A basic battery charger is not a 'float charger' nor is a trickle charger. Simply charging a battery does NOT mean it is good. It must maintain a full charge under load, meet the specific gravity specs by testing with an hydrometer or bench tester at a shop. When the vehicle is idle, i.e not running, you keep the float charger connected so it will maintain a full charge so it is 100% ready to go when you need it. Keep it connected if tractor is idle for 10 days or more. I just keep mine on every time when idle and use the DELATRN BATTERY TENDER units –reliable and guaranteed. Your local trusty starter/alternator/generator shop guy can bench test the battery, generator or alternator, ammeter, voltage regulator or cutout, ignition switch, Period preventative maintenance is the key. Check wiring belt tension often. If your generator does not have a belt tensioning bracket, it will not keep the belt tight and thus will not keep the battery charged. I use



Tim Daley(MI)

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02-16-2020 05:35:56

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 Re: Charging issue on my 641 in reply to Tim PloughNman Daley, 02-15-2020 07:26:22  
Thank you for this information.

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02-14-2020 05:25:40

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 Re: Charging issue on my 641 in reply to shoprat, 02-14-2020 05:06:12  
Your symptoms are inconclusive to me at this time. Grab a voltmeter and attach it to the battery. With the engine off, and after it has been sitting for a while, you should have approximately 6.0 - 6.3 volts. Then start the engine and run it above an idle speed (say, half throttle). It should slowly climb to approximately 7.0. If it passes that test, turn on the lights. With the engine at working speed, the voltage should remain steady.

If it passes all of these tests, your system is working properly.

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02-14-2020 06:19:28

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 Re: Charging issue on my 641 in reply to Bern, 02-14-2020 05:25:40  
Thanks, Bern. I will do that as soon as the outside temperature comes back up. I don't understand why when turning on the lights, the needle moves to the charging side instead of discharge.

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