Alternator shot....or just underpowered?

[knac1234]

All,

So we actually got some decent snow this morning, and of course I had to take the SIII to work!

After starting her up, meanwhile chiseling the thickest ice (and breaking my scraper) off the side windows, I turned on the heated windscreens and rear glass (the front windscreen....5 minutes....ice came right off :thumb-up:).

Anyway, wife in tow, we had everything going.....lights, wipers, heated glass, heater. I noticed the alternator light glowing red. So, I turned off everything "unnecesssary" and after 5 minutes of driving the light went out.

So, do you all think I just overwhelmed the alternator (does the light come on if it is working, and just maxed out) or do you think it is toast and I should test it/replace it?

That said, I knew that if everything was running that the alternator output would be too little. Would a beefier Lucas work or an aftermarket one work.....and more importantly would the wiring handle it? (I went through almost every wire in the truck....stripped the tape off, replaced, and all new connectors everywhere).

Thanks,
Julian

[jonnyc]

Assuming you still have a Lucas, I would highly recommend that you do the Delco conversion. It's really easy, inexpensive, and a vast improvement.

[I Leak Oil]

X one million on the delco conversion. Run the output wire right to the battery. That will bypass the existing harness altogether.

As far as the problem goes, only way to know is to have your existing alternator tested. It could be going or you could have just overloaded it, in which case it will go soon if you continue to max it out.

[albersj51]

My generator did this before I put in a delco12si 78 amp alternator...no more issues. I agree, get it checked, but ill bet your alt is just underpowered. The Lucas.one didn't exactly pump out a lot of amps, and with that much running it will be working overtime.

[knac1234]

All,

Thanks....

So, it seems the consensus is:

-Get a Delco alternator
-There are no wiring over load problems (Jason.....78 amps sounds good if the stock wiring can handle it). What's the highest amperage Delco I can put on there, using the "kit", without worries??
-Are Ike's brackets only necessary if I want to mount it "on top" as opposed to the original location?

If my Lucas will soldier along, I will keep it until next winter, as the drain/strain placed on it is no doubt a function of the high amp accessories I ran with the rest of the normal stock stuff today (3 sets of heated glass, which I use only in the winter-or flukes like today-anyway). Got to put the funds into the steering issue that surfaced. Also, my door seals clearly let blowing snow in.....am thinking about doubling them (door side and body side).

Thanks,
Julian

[albersj51]

I believe delco makes a 96 amp alternator in the 12si version. As for what the wiring can handle, I've got no clue. My old rats nest handled the 78 amps just fine.

Ikes brackets are nice! However, I put my alternator in the generator position using the prudish brackets and some bar stock. if you use yours off road, moving it up top may be a smart move .

[mearstrae]

I've been using the Delco "One Wire" 100amp unit, with no issues. I never see this particular unit mentioned here. It handles all the accesories and will handle the dual battery setup I'm thinking about, when the elec. winch goes on. Mines mounted on top with home-made brackets, and the nice thing is, with the position, I can use many different sized v-belts to drive it.

'95 R.R. Classic LWB
'75 Series III Hybrid 109
'70 Rover 3500S

[siii8873]

Julian,
the wiring only needs to handle the loads they are feeding so individual fuse protected wiring should be fine. Updating the alternator will not increase any of the amp loads on these circuits.
Bob

[knac1234]

Bob,

Thanks for the clarification.

Although I added several electrical goodies (2 front heated windscreen panes; 1 rear heated glass; fog lamps; rear work lamp; basic radio; cig lighter), I ran all of them off a separate fuse box that itself is fused, and then of course its circuits powering these items are fused. Relays were used on heavy load items (most of those above). This allowed me to keep the stock harness, not hacked about at all, in shape and in good working order by replacing all connectors and cleaning it up (not to mention the ability to trace components via their original wire colors).

So, per your comments, I should be fine then running a higher amp alt. No problems driving home or starting up, so I think the Lucas has some life left in her!

But, when the time comes to replace it, I will without a doubt go the way you all have recommended!

Thanks,
Julian

[SafeAirOne]

I have a 96-amp 12si in my SIII. Like Bob says, the alternator doesn't put out 96 amps unless there is a 96-amp demand from your electrical system.

I'm sure that when you installed the secondary fuse panel, you used wire sized for the anticipated electrical load of each new circuit, so you'll be just fine, providing you fed your new fuse panel directly from the battery/big post on the starter and not by tacking it on to any existing wiring (like the 12v supply to the existing fuse box, for example.

[antichrist]

Assuming 100amps for a 3' run (to allow for routing) #10 would be fine. I'd probably use #8 to get the volt drop even lower, but would be comfortable with #10 if it was already there.
For reference, #12 would reduce the voltage to the battery by 0.5v.

[knac1234]

Mark & Tom,

Agreed on your electrical thoughts. I think I did a pretty good job of it when I was working on the Rover's electrics late last year. The new fuse box was wired as follows:

-8 gauge wire from solenoid live to very large fuse (forget amperage, but it matches the new fuse panel's rating!)
-large fuse via 8 gauge wire to new fuse panel
-each circuit stands alone and is fused according to the rating of the device powered
-each circuit with a high amp draw item (all heated glass, fog lamps, rear work lamp) has a separate relay
-wiring to each of these high amp items runs the right gauge wire (I think 10 or 12 gauge depending on the item)

So, that, in conjunction with a stock clean system, I think is pretty darn safe, and so the alternator recommended should be safe.

No problems again this morning.....one turn of the key and she fired up instantly even after sitting all night outside in the cold wind and more snow!!! Think the Lucas is fine right now.

Julian

[SafeAirOne]

I think is pretty darn safe, and so the alternator recommended should be safe.


Yeah, you'll be fine with that setup. :thumb-up:

[LR Max]

Test the alternator first. Grab your volt meter and put the black on the negative of your battery and the red on the positive of your battery. With your engine running, measure the voltage across the battery terminals. If it is a ~12v or less, your alternator is toast.

Also make sure you increase the RPMs of your engine while testing. Your alternator might not provide optimum voltage at idle. But at ~2k, it might be putting out 13.5~14v which means it is good.

As for the light. My low voltage light is all messed up. As I increase RPMs of the engine, the light goes from a dim to full glow. Then back at idle it is dim :rolleyes:. However I don't have any electrical issues (it has been doing this for months and I haven't had to put a battery charger on it).

[I Leak Oil]

Just curious, on a SIII what's the path from the alternator output to the battery? What does the current go through(switches, connectors, etc.)? Might want to look at it and ask if you want the increased amperage going through that stuff.

[SafeAirOne]

Just curious, on a SIII what's the path from the alternator output to the battery? What does the current go through(switches, connectors, etc.)? Might want to look at it and ask if you want the increased amperage going through that stuff.

Only going by my 2.5 and the SIII schematic, but the internally-regulated alternator output goes directly to the big stud on the starter with nothing in between.

[I Leak Oil]

You mean Rover made some attempt to wire something correctly?!:p

[LR Max]

Only going by my 2.5 and the SIII schematic, but the internally-regulated alternator output goes directly to the big stud on the starter with nothing in between.

X2. There are other wires that go to the wiring harness to control it but the important wire is pretty much wired to the battery via the starter solenoid stud.