Battery going dead

[JimmyC]

My batteries are going dead on my 710. I checked the voltage at the batteries and it does not rise with engine running. I opened up the Molinex connector that goes to the alternator and there is quite a bit of corrosion in there, probably my problem. I will replace it when I have time or have to, but hoping to clean it for now. Does anybody have any suggestions besides just spraying it with contact cleaner and deox? Also, my charging failure light never came on. It does come on with ignition on/motor not running. Any thoughts?

[rmel]

The Alt light could appear to be working normally as long as your Battery is at least 18V AND the
DF output from the Alternator is good AND there is a good connection to the regulator. Though
if you look at the bulb you may see it very dimly lit.

What lights the Alt lamp up is the difference in voltage between the Battery and the DF output.
Normally, a ON Alt lamp and a running engine is an indication that there is no voltage from the
DF output indicating a bad alternator.

I'd try using alcohol and a dental pick to get that oxidation off the pins. A very lite touch of
dielectric spay on the terminals to prevent more oxidation. Do a few repeated insertions to
scuff up the mating surfaces.

[JimmyC]

Thanks RMEL. I hit the connector with some elecroclean as it was the only thingI could find. Got it surprisingly clean. I plugged it back in and cranked it up and the voltage went way up, like 39 volts according to my meter. I unplugged and replugged a few times and it was showing 28.something when running, more or les normal.

I hate to sound dumb, but what is DF voltage?

Also I noticed that the two forwardmost of the six wires inthe connector have been clipped off at some time.

I am away for the next month. Just wanted to get it going in case somebody needed to borrow it. I wil try to look at the wiring diagram. Might order a new connector for my next maintence go.

[rmel]

I actually mistakenly referred to DF when I meant D+ !!

There are two outputs from the alternator, D+ and B+.

B+ is the high current output to charge the battery.
D+ on the other hand is monitored by the regulator
to control the amount of current on the "DF" the field
winding to output more or less voltage. The D+ and
B+ outputs are connected through the warning light.
Thus id no D+ then warning light it ON.

Sorry if I was a bit confusing.

cheers,

[Texas710]

I "lost" my alternator one time on a trip. It was scary watching the batteries drain in real-time, being over 100 miles away from the house. Turned out, it was the grounding lug for the alternator that had worked loose, easy fix, but definitely something to check.

[ChickenPinz]

If you saw variability with moving the connector around, and you've already reported a lot of corrosion on the contacts, honestly, I'd replace that connector. It's a pay-me-now or pay-me-later situation. I'd not consider it urgent (stop driving now), but I'd consider it a risk in the field if you don't replace it as the plating is likely damaged and it's going to corrode much faster in the future. You don't need to change the whole connector -- just the contacts.

[JimmyC]

I am finally getting around to changing the connector and am hoping somebody who has done so can give me some pointers. I bought the wire set that goes from the alternator to the cowl and the molenex connector and spade terminal to change out the piece on the main harness. To get to the alternator to molenex wiring do I go in through the cooling fn and alternator or take the cowling off? I seem to recall having to take the carbs off to get the cowl off. I want to swap out my carbs anyway. Any pointers?

[rmel]

If you remove the top front "tin" which is forward of the Front Carb, that will
give you acess to the back side of the alternator and the Molex connector.
You do NOT have to pull the carbs.

[JimmyC]

Just about finished. Replacing the spade terminals and female molenex is pretty easy, cheaper, and probably better than splicing in that pigtail you can get from SAV. If someone has a suggestion for a crimping tool for those factory crimp connector I would appreciate it. Mine was obviously not the right one

[rmel]

I've had this Molex hand crimper for years, never has failed me
and works for other "similar" type barrel terminals. Expensive but
don't settle for a knockoffs. Amazon link below, you can search
for better prices out of places like Digikey etc. P/N 63811-1000

https://www.amazon.com/Molex-63811-1000 ... B00OVF2AKI

[JimmyC]

Well all back together and working fine. For somebody else doing this, it is not very hard. I suggest buying new spade terminals and installing them rather than putting one of those SAV pigtails on. The trick for getting the main harness connector apart us to use some small needle nose pliers to grab the spade and push it back. The crimp connector has a little barb that holds it in place. You can squeeze it down with the needle nose pliers. Not sure how to get the alternator end apart, but as expensive as it is it is worth a try. Generally, the plastic parts can be reused, just the crimp connectors themselves need to be renewed. Regular crimpers for insulated connectors do not work well. Buy extra crimp connectors. The Molex hand crimper is expensive. Is there a good one that is cheaper? THanks to RMEL.