battery not charging new alt

15392 Views 33 Replies 8 Participants Last post by sevensda1, Nov 2, 2020

CSAGQ

Discussion Starter · Jan 5, 2011

hey everyone
i had a issue with this couple months ago where my battery wasnt charging so i replaced the alternator and my battery was charging fine after that.
now since 2 weeks ago my battery has been going dead while the engine is running!
i checked the cables, fine. the light in the dash goes out and stays out once the engine is on (it is also completely out and not DIM)
heres the very annoying part of it the battery takes charge from a jump start and from a 240v battery charger! but not from the alternator!!
its driving me completely insane and cut my holiday short because i didnt want to be stranded!

could someone please give me a hand on how to properly troubleshoot this problem because no way in hell i can throw around cash to buy new battery and alternator here and there!
cheers!

21 - 34 of 34 Posts

ITS A FORD NOT A NISSAN

· #21 · Jan 6, 2011

that is just a noise supressor (i think), its to stop static interference on your radio

CSAGQ

Discussion Starter · #22 · Jan 6, 2011

ohhh ok
right everything wicked
thanks everyone for their help

14.75v @ 2000rpm
drops to just shy of 14v with high beams on

91shorty

· #23 · Feb 11, 2011

Curtis129
How did you fix it?
This sounds like what mine is doing 12.77 volts @ 2000 rpm

ITS A FORD NOT A NISSAN

· #24 · Feb 14, 2011

Curtis129, i have sent you a pm , i just re-read this and i must have miss-read the voltage figures you posted after you fixed it, 14.75 volts is too high , it might kill your battery at this voltage

im just guessing but how it was wired up with out the charge wire being connected may have burnt out the sense wire or a connection in the alt related to the sense wiring

CSAGQ

Discussion Starter · #25 · Feb 15, 2011

91shorty said:
Curtis129
How did you fix it?
This sounds like what mine is doing 12.77 volts @ 2000 rpm

wired it up correctly (doh)

cheers ford not nissan i sent you a reply

jeffs5

· #26 · Dec 20, 2011

ITS A FORD NOT A NISSAN said:
now i have rewired mine so the colours will be different

the 2 top wires from factory should go to a plug ( mine are both red) factory should be one white with red stripe (D+) the other should be white and a little thicker ( sense)

the main power out just under them (i ran 2 thick red wires) factory should be a thick white wire that bolts to the alt, i have pulled the rubber boot back a bit so you can see the nut,

the thick white wire is still connected on mine but it has a black cover over it as seen running along with the red wires

Hi ITSA Im'e doing this with my alt. why the two thicker cables from the stud on rear off alt., do they both go too main batt. +

ITS A FORD NOT A NISSAN

· #27 · Dec 20, 2011

jeffs5 said:
Hi ITSA Im'e doing this with my alt. why the two thicker cables from the stud on rear off alt., do they both go too main batt. +

in that pic one goes to the main battery and the other went to a fuse panel i put in on the passenger side (less wires everywhere),

as it is the standard alt in mine one wire of that size is enough to reduce voltage drop, with a 120 amp alt i would go a thicker wire or 2 wires to make sure it can carry the full load to the battery when winching

jeffs5

· #28 · Dec 20, 2011

ITS A FORD NOT A NISSAN said:
in that pic one goes to the main battery and the other went to a fuse panel i put in on the passenger side (less wires everywhere),

as it is the standard alt in mine one wire of that size is enough to reduce voltage drop, with a 120 amp alt i would go a thicker wire or 2 wires to make sure it can carry the full load to the battery when winching

Cheers for that! I still got original for now! Will do the heavier cable to see if i can get some more out of it!Whats a norm voltage too the batt. when cruising? as it is im'e getting around 13.8 at the batt via monitor.

ITS A FORD NOT A NISSAN

· #29 · Dec 20, 2011

jeffs5 said:
Cheers for that! I still got original for now! Will do the heavier cable to see if i can get some more out of it!Whats a norm voltage too the batt. when cruising? as it is im'e getting around 13.8 at the batt via monitor.

best bet is to take a voltage reading from the rear of the alt , it should be around 14.2-14.4 volts, that is what should be getting to the battery, so to me it looks like you have a .4 to .6 volt drop along your charge wire and i dare say as the load increases so will the volt drop

if you do the mod posted earlier in this thread where you dissconnect the sense wire from the alt and run a new one strait to the battery then the battery will recieve the 14.2 odd volts that the alt is trying to give it but cant due to the factory wiring

jeffs5

· #30 · Dec 20, 2011

Thanks ITSA!, Will do the charge wire and go from there. cheers Jeff.

RosieBear

· #31 · Dec 20, 2011

Does the new sense wire require an inline fuse????

ITS A FORD NOT A NISSAN

· #32 · Dec 20, 2011

RosieBear said:
Does the new sense wire require an inline fuse????

i would recommend probly a 20 or 30 amp fuse to be safe, although there is no current flowing through that wire , it just takes a voltage reading so the alt knows how many amps to produce to get the voltage correct at the battery

ITS A FORD NOT A NISSAN

· #33 · Dec 20, 2011

glort said:
I disagree that is too high especially when it drops with the lights on to under 14.

Battery's will last longer when charged to the high side than when charged to the low side due to the higher voltage reducing sulfation. Anything under 15V is generally accepted as being OK on a Vehicle.
Slightly higher voltages also reduce amp draw which is beneficial to most DC electrical devices and switches anyway.

There is less than .4 of a volt difference between what you are saying is too high and what is right and given the fluctuating voltages the vehicle will experience in normal use that will be a lot more than that, I would say it is totally irrelevant.
No doubt this measurement was taken with everything turned off and the application of the brake lights, turning the radio up, using the AC and certainly a combination of these things as experienced in normal driving will easily take the edge off the voltage and probably bring it right back to what you think is the safe voltage or lower.

The amount of time things are being used in the vehicle I would imagine would greatly outweigh the amount of time it's sitting there absent a load at all. It is a very good thing to give a battery a topping off now and then so I would be pleased if this were my vehicle and i was getting that voltage.

I'll bet when the thing is stuck in traffic at night with the AC or demister on, the voltage will still be very low so at worst, the slightly higher voltage would bring the battery up quicker and go some way to making sure when it was switched off it wasn't a bit low which is what really knocks battery's off fast.

All that said, If you actually look into battery charging, there are all sorts of theroys and calculations and recommendations and there is no one universally agreed voltage. Even float and cycle end voltages are different.

Anyway, like I said, personally I'd be pleased if my alt was outputting this voltage at low or no load.

From memory in this instance that voltage was unregulated due to a break in the voltage sense circutry , i am sure the voltage would have kept climbing and boiled the battery dry

unless the alt is designed to output that voltage then there is an issue somewhere

sevensda1

· #34 · Nov 2, 2020

i have same problem as the guy who asked 1st question i got a brand new alternator thats not charging the battery ,batt chargers from 240v charger or jump start but dies while driving replaced battery also same thing ...Even brand new battery in also car wont run moment battery is disconected battery fuse is fine got me stumped any and all help would be much appreciated car is stock with a lift n winch (how i brought it)tb48de 4.8L petrol

21 - 34 of 34 Posts

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