With help from the forum, I've been chasing electrical demons. I found no unusual drains, which is what my garage suggested, but with the cold weather setting in I am being left to sit again. Not fun.

So far, I found some loose battery terminals and cleaned and shimmed those until very tight, then charged battery, took vehicle (2003 Disco II HSE) to Advance auto for testing.

When the battery is on the charger it reaches a good charge, 13.5 volts or more, and I'll start okay for a few times. After a half dozen starts, as voltage measure closer to 12 V by my meter, it no longer cranks the engine. This would point to alternator not charging perhaps? Or bad connection to starter? Here are the numbers:

Battery: 13.78 volts (a 700 CCA Interstate, about 3 months old)
measured: 556 CCA
Result: Good Battery
Temp: 53F

Starter
Result: Low cranking amps
Voltage: 11.05 V
Amps: 1.8
"Starter Amp draw is low with ok starter voltage, check starter circuit for loose, worn or corroded wiring."

I checked the obvious ground to frame and fusebox connections and they are clean and tight, and looked up at the starter connection and visually looks tight and clean. Not sure what to check, does this point to some other wiring or starter issue?


Alternator
"no problems"
No load: 12.95 V
-1.5A

Loaded: 13.38 V
-3.6 A


I understand this on the low end of acceptable. Yet, what I've read here says a bad diode would show a significant drop, like 30%. Do you guys think I keep looking for loose connections decreasing power to starter, or assume alternator is not putting out enough to charge battery for repeated starts? It's not a cheap part to swap without knowing.

Thanks a ton, Jeffery

 

Your charging system is too low, you need 13.6 at the low side and up to 14.4 volts or the system won't stay up.
Have you tested the draw on the system when the engine is off, if no do so and get back to us.

 

On the bad diode - that will show up as low amps output, but volts may look ok with very low load. Example - with one diode out you might crank OK (short load) drive OK on highway, but once it rains, you add wipers, lights, AC ; and voltage drops too low to keep battery up with increased demand. You should be able to idle, like Mike says, with 13.8 - 14.2 volts, and as you turn on extra loads should not drop below 13.4 - 13.6. Might want to check underhood fusebox wires (large ones in front) and the largest fuse link for corrosion and tightness. The big brown one is from the alternator. Page attached.

 

Thanks guys.

I had a thread earlier this summer where I got some help going through all the draw stuff, pulled every fuse, and it looks in spec, starts a little high but quickly drops to .03-.04 amps overall.

I had checked the wires for tightness, but not pulled them. Took them off and the underhood connections are shiny new.

Mike, I guess I will bite the bullet for a new Alternator, or more likely a rebuilt bosch alternator. It looks like 03 and 04 spec a Bosch, maybe with higher amps than the the 4.0 D2s?

However, I am now looking back at my own post seeing that in July the same battery rated:

July: Batt voltage 12.99 with 731 CCA at 88F (rated for 700)

Jan: Batt voltage 13.78 with 556 CCA at 53F.

I thought that CCA were adjusted for temp, which means even with a full charge this thing is putting out poor amps. Is it that simple? I am having serious doubt about what Advance Auto considers "good" but not sure how to interprete the numbers.

Thanks again, J

 

Take a look at this easy test I did. Has pix of reading with various conditions (truck off, truck at idle, at idle with lots of things turned on). https://landroverforums.com/forum/ge...ter-pix-44317/

Try another auto parts store (different meter and counter expert). I don't think many starters will crank a Rover at 1.8 amps draw.

 

Thanks for your help guys.

Despite the battery saying it was "okay" at Advance Auto, I took it back to Firestone and they agreed that 500CCA was not up to par, especially after I charged it fully.

They gave it "marginal" rating and pro-rated something to me. So I got my THIRD Interstate battery in like 3 years, although I now dread giving them more money. The new battery is back to 700 CCA.

Mike suggested my alternator was not up to snuff, so I figured maybe it is the alternator's fault for killing off batteries and not Interstate's. I decided to replace it with a rebuilt, and wanting to slightly overkill went with a 150 amp Bosch, hoping to crank up the juice. I got this from EagleElectric on ebay for around $120. It looked like a monster compared to the 120 Amp OEM.



Note how the positive and negative cable terminals are located much lower, toward the bottom of the unit. This means that if someone were foolish enough to wrestle it into the cradle and bolt it in, thinking they could attach the wires at the end, they would have to remove it and start over.

Got it in and took it to be retested. I am now putting out:

No Load: 13.66V
Loaded: 13.10V

So I have gained little if anything! I know this is a rebuild, but it certainly looked clean and the dealer has a good reputation. So did I do all this for nothing, or does it point to another problem? Mike's saying "you need 13.6 at the low side and up to 14.4 volts or the system won't stay up" but I am still not near that and a new Bosch is like $500.

Thanks again, J

 

The 150 amp alternator - did you have it tested at the parts store? Sound like one of the diodes might be out and it is not putting out full amps.

When you say "no load" you mean engine running, but that's all? Load will be about 15 - 18 amps. Fully loaded can top 100 amps (80 - 85 on my D1 without any fogs or roof lights).

Here's why I say that. Lead acid batteries are 2.2 volts per cell, so will read 13.2 without charging and no load. So if you can't stay above that point, something is not right. There is the big wire on the alternator (output) and a smaller wire that suppplies 12 volts to "excite" the windings. Have volts on both of those?

But new alternator looks honkin'.

 

Thanks, Savannah. I did not have it tested before installing.

I guess I made the assumption it was rebuilt and tested. To show my ignorance, I imaged the small wire was a ground of some sort. The thought of tearing this thing out again is killing me, but so is keeping it if it is not right.

To have it tested properly, do I have to remove and bench test it. I was under the impression these are always tested in vehicle.

The procedure, at Advance Auto and Firestone has been to take a reading at idle with nothing on (I think this is no load) then a reading at 2k rpm with high beams, radio and heat on (I think this is loaded). The battery alone tested 12.35 volts, so I am still boosting it when putting in 13.1, but maybe not enough?


Thanks for your insight. I am just learning, J

 

It's about 38F here. My D1 old Interstate battery reads 12.98 volts just sitting there (so at 80F it would prodably make the 13.2). Crank truck, nothing on but engine, 14.09 volts, 16 amps coming out of alternator.

See attached page from RAVE. Has pix of back of alternator. Alternator ground is by the case, not a wire. The big wire (brown, with a red end on it) is the main plus volts power from the alternator and heads off to the underhood fusebox. The smaller wire, marked in pix as C0185, is the hot lead that tells the alternator to start dancing. It actually goes through the battery indicator light on the instrument cluster. Should read a plus volts from there to ground.

Kind of hard to miswire these. And if small wire is off, alternator has no output. Truck is running off battery only.

Check fuse 27 inside the truck. Also, the battery light should come on when key is turned on before truck is started.

Normally the store wants to test alternator on their bench device inside. The volts you have mentioned would indicate a failure to me, so I don't think it can easily be tested in the truck.

Attached pix of back of alternator and schematic of the charging system. Also pix of why many of us will be charging....

 

Thanks for the pics. It is definitely wired correctly, only because they made the hot leads two different bolt size and it would have been impossible for me to do it wrong. The supplier has been very good, but here was his stance.

"I am in this business for over twenty five years. specialized on Bosch alternators
Bosch alternator never goes higher than 13.5 on ranger rover cars the reading is very good, also it's important for you to have good heavy duty high cc battery and this alternator has bosch regulator not made in china or aftermarket. try it couple weeks if you don't like it we can refund you back I have sold a lot and do'nt have any complains"

I am now thinking I will bench test the old alternator and compare it to numbers that were in the car. If it produces much more outside the vehicle, that might point to a definite bad connection somewhere in my loop. Though I can't imagine what else there is to check. Thanks again.