alternator charge check

[adamh]

how do you check the charging circuit of the mk1.5?.. to even check everythings connected properly i guess i have to buzz out the connections.. i should?.. see a connection between battery positive terminal and the thick wire that bolts onto the alternator right?.. any other good checks for an alternator?. im not majorly worried, i think its been due to not actually running down the road.. but all the starting and stopping without moving seems to be flattening the battery after a while after a full charge. also to be noted by alternator belt was a tad flappy when i checked so ive tightnened that up and the battery is charging again over the next two days..

[Jiff Lemon]

Simple charging checks:

Ignition off: Battery should be a healthy 12.4V or more
Cranking: Battery voltage shouldn't drop below 11.4v
Idling: 14-14.9v
2k rpm with load (headlamps, Heated rear Window, Heater blower on full): 13.6 or above

If it fails any of the above we can first check the votlage at the alternator. So positive lead to the postive terminal of the alternator, earth lead to the alternator body.

If you're seeing the above readings (idle and load) at the alternator but not the battery, you've got Voltage drop. So....

From Postive on alternator to positive on battery: <.5v
From alternator body to battery negative: <.5v

Anything above those and you better be resoldering, or beefing up cables.

[adamh]

cheers jeff :thumbsup: i'll run them through and see whats what with a fresh charged battery

[adamh]

what i have found so far.. with car off at the battery 12.8V
with car running at the battery 11.6v

i checked the charge fuse for breaks: none, when running charge fuse voltage check: 11.6v
i checked the links in mk1.5 wiring from N1 to alternator plug (3 continuity o.k)
i checked the yellow wire on alternator plug straight to charge fuse in mk1 bay.. continuity..

somethings up somewhere, its not charging.

im going to check the N1 connections again tommorow (this time with wiring guide).. and also take out the AFM and filter and have a probe about that wiring there.

when you say: " positive lead to the postive terminal of the alternator, earth lead to the alternator body."

...do you mean the big thick chunky bolted connection on the side of the alternator is that the positive you are refering to? .. and earth that against the alternator body (voltage check etc)?


when doing the mk1.5 wiring.. you split the thick main power feed from the alternator (the one you are refering to i think).. one goes off to the M2 black and white to power up all the cars electrical systems.. this can be confirmed as the the car runs!.. and all electrical systems work.. now, the other end of the split should then get joined back onto the starter terminal to send feed back to the battery.. so .... i'm hoping ive missed that connection from alternator back to starter terminal (where the battery joins on) will check in the morning. the alternator was professionally rebuilt & tested while i had the engine on the bench.. if its that i'll eat my socks!..

[adamh]

am i also to understand the alternator needs power to operate.. like a regular ancillary?.. ive not seen either the alternator light or battery light work on the dash yet

[lodgeman]

have you connected the wire up?:hidesbehi :rofl:

[adamh]

erm... all i do know is im good at missing bits out :D
















:moon:


im gagging to dirve this thing.. spent this afternoon battling myself not to take it down the road ..was trying to kid myself with excuses before m.o.t..

petrol fill.. station?.. nah , could get rumbled by rozzers and they would say use a jerry...!
light bulbs?.. nah they would say pick one up in the other car lol
cooling checks ? .. no excuse!..
i had a hard time, in the end the alternator checks grabbed my attention :freak3:

I WANT TO DRIVE IT! :jump:

[adamh]

i checked all the wiring again, its spot on, cables are beefy. couldnt work it out!.. checked MK1 fuse box, somehow the 10A engine fuse had blown.. i think it was a while back when doing up the chunky bolt that holds the live on the alternator i shorted the bolt against the alluminium bulkead with the spanner.. that must have been when it blew.. it sparked lots then. so i put a new fuse in, bingo.. charging at 14.6V at the battery :) ta for pointers guys..

to clarify the 10A engine fuse feeds the mk1.5 BK/YE alternator wire with 12v supply for the alternator.

alternator and battery lights working fine.

[Jiff Lemon]

Sorry I missed this adam, spent the day swapping a 3s-ge (bloody awful job!)

Should have been one of the first checks; If the warning light on the dash DOESN'T come on with the ignition, the alternator will not start to charge.

[adamh]

i'll know next time, i'll carry a full set of fuses i think!.