**Starter Battery** Blues?

[MountainBikeRoamer]

Okay --- went back and extra-thoroughly re-tested the Isolator.

Realized that what one of Scalf77's earliest responses had stated truly needed to be done ---- in order to fully, properly assess the isolator --- was that there needed to be not just a test for continuity across the isolator's terminals --- there also needed to be proper testing to see that there was only one-way continuity across those terminals. In short (hah, electrical pun....), the isolator's internal diodes needed to be tested to make sure they were properly behaving....Diode-ey.

(Diodes should only allow current to flow through them in one direction.)

So.
Got back out the trusty Craftsman Multimeter....and set it up for Diode Test/Check parameters.



The instructions are remarkably straightforward for testing the proper operation of a diode:

1) If the diode is good, you'll measure current flowing across it in one direction, but not the other.

2) If the diode is bad, you'll either a) measure current going in both directions (shorted out diode) or b) measure zero current going in either direction (burned out diode.)



So anyway....
.....on to the testing procedure for the Sure Power isolator that Scalf77 presented earlier.
(My results indicated in green.)

--------------------------------------------------------

INSTRUCTIONS FOR TESTING A SURE POWER ISOLATOR WITH OHMMETER*:
1. Remove all wires from the isolator.

2. Using a needle movement ohmmeter RX-1 scale or a digital ohmmeter diode scale, hold the Red* probe on the terminal "A" and with
the Black* probe touch terminal #1 and #2, and the "E" terminal for 3A isolators (group 2), and the "R" terminal for (group 3) isolators.
A good isolator will show a current flow from "A" to #1, #2 and "R", and no current flow to "E".
SUCCESS:
Current flow from A to #1: display shows 0.380
Current flow from A to #2: display also shows 0.380

3. Next, hold the Black* probe on the "A" and with the Red* probe touch terminal #1 and #2 (terminal "E" and "R", if used). A good
isolator will allow no current flow from "A" to #1, #2 or "R" and will show current flow from "E" to "A".
SUCCESS:
Current flow from A to #1: ZERO
Current flow from A to #2: also ZERO
Current flow from E to A: YES -- display shows 0.395

4. Hold one probe on the aluminum heat sink, being sure there is contact by scratching through the protective coating. Then touch
with the other probe, terminals "A", #1, #2 (the "E" terminal for 3A isolators [group 2] , the "R" terminal for group 3 isolators). A
good isolator will show no current flow.
SUCCESS:
Current flow from aluminum case to A: ZERO
Current flow from aluminum case to #1: ZERO
Current flow from aluminum case to #1: ZERO

5. Colored terminal indicates "E" post on group 2 isolators and "R" terminal on most group 3 isolators.
*On some import ohmmeters, the red and black probes are reversed for these tests.
**If using a digital ohmmeter, a diode scale MUST be used.

--------------------------------------------------------

Conclusion:
As far as I can see, this Sure Power isolator is still 100% functional and within spec.
(*Scalf77 and others, it would be great if you weighed in and confirmed this?)


At this point, it seems that the following two priorites stand out:
1) attempt to address/remedy the 0.2 volt "line loss" between the isolator and the starter/chassis battery (install a new run of adequate gauge positive wire between the output terminal of the isolator and the positive terminal of the starter battery)

and

2) replace the starter/chassis battery (as its resting voltage of between 11.9 and 12.0 isn't very encouraging.)

Still.....really need to figure out why the starter/chassis battery seemingly overcharged/boiled.
Has adequate investigation of the the alternator end of this equation still been neglected? So far, it seems that the alternator (and its associated voltage regulator) have been performing exactly as they should do --- apart from a brief surge to 15 volts for a minute after starting the engine a few days ago, it has been supplying a correct 14.2 to 14.7 volts to the starter battery, whether there is an isolator in the circuit or not.

Boiling/ruining batteries gets expensive (and old) pretty fast.

[Flux]

Short in the battery causing excessive drain and causing the alternator to react and send high volts??

[arctictraveller]

This probably won't help you, but I use a simple / inexpensive relay to combine all batteries when the engine is running. When the engine starts, the relay is energized by an ignition source of voltage, and when the engine is shut off, that voltage drops out, opening the relay and preventing the discharge of the start battery from house loads. So far, the batterys have lasted several years without problems. With the relay, there is no voltage loss like you see through diodes. As long as there is no excess resistance in the cables (resulting in a voltage drop, or as you put it "line loss") the regulator should supply the correct voltage based on the battery's state of charge (voltage). The regulator measures the battery voltage, and adjust's the field current of the alternator to the correct output voltage. If one of your connections had excessive resistance (resulting in a voltage drop that the regulator sees), the regulator would keep raising the voltage, possibly resulting in a boiled battery. Since it's clear your start battery is toast, I'd replace it, make sure all your connections are clean and then take the voltage measurements again.

[daveb]

Originally Posted by Flux

Get yourself a Blue Sea 7622 and win.

X2 and get a AGM starting battery

[arctictraveller]

Originally Posted by daveb

X2 and get a AGM starting battery

That's ok, assuming that the house batteries are also AGM, but mixing different battery types will add even more complications to the charging issues.

[Scalf77]

OK, good test data, which made me go back through the whole thread. Your first reported voltage that got us concerned of a bad alternator was your reported readings of 14.8 & 15.0 drifted down to 14.6 and 14.8. You didn't have a measurement on the A terminal but we expected it to be in the mid to high 15's .


Somewhere in your excellent troubleshootinhg the volategs you reported

Alternator output terminal to ground. 15.13 volts
- Isolator chassis battery post to ground. 14.33 volts
- Isolator house battery post to ground. 14.53 volts
- Chassis battery positive post to ground. 14.13 volts
- House battery positive post to ground. 14.53 volts


- Alternator output terminal to ground: 14.38 volts
- Chassis battery positive post to ground. 14.18 volts
- House battery positive post to ground. 14.38 volts


So my initial assesment was this daya was the altenator was good, voltage appeared to be regulating fine. Then I hit the flaw in my (10,000 ft assesment). I just glanced over the new reported data that showed batteries down around 14.53 & 14.53, I was still thinking of the possible high 15"s out of the alternator. I suspected that we were not getting feedback to the alternator and thus driving the output high. Where and how the alternator gets voltage feedback depends on the alternator, many of the old ones just took the feedback off of the output lug, some nowdays go through the PCM, or as somewhere off of the battery.

Anyhow, now after re-looking at the data, I would agree with that it appears to be working fine (your additional testing confirms), it is possible when removing everything that you cleaned up a contact or something, but you're new measurement data is much better than the 14.8 and 15.0 that originally got us here.

The diode isolator is still a clean way of getting power to multiple batteries, and even the dreaded "voltage drop" really depends on the alternator feedback design and issues they could present.

I hope this helps in cleaning up my feedback, sorry for any confusion.

I used the term 10,000 ft assessment, this is in reference to my previous job. Many times when working on highly visible issues, you would get managers dropping by the lab asking for status and giving their input on what the problem was. We considered this a manager fly-over, and thus the 10,000 ft assessment. It can be very easy to not take in all the data, and unfortunately that is the same problem with forum feedback.

-greg

[MountainBikeRoamer]

Hey Greg / arctictraveler / flux / DCHitt / daveb -

Thanks much!!!
Tons of great learning going on here.

Greg, it's very cool to hear that you have come to assess the overall latest test data as confirming correct operation of the isolator / alternator / regulator circuits.

So now, for sure:
Would definitely like to address the 0.2v line loss (voltage drop) between the isolator output post and the starter/chassis battery....but it looks like that wiring traces a somewhat less-than-linear path between those two points, possibly routing through another intermediate under-hood electrical component or junction before finally reaching the positive battery post.

I'd like to think that you could just run a second, clean and uninterrupted positive feed wire (of sufficient gauge) alongside the current isolator-to-starter-battery posiitive feed path (much like running a second ground), but intuitively I have concerns that this isn't as cut-and-dried a situation as that. (May upset other circuits that count on that voltage/current to feed through **them** first before reaching the battery. And those components may be, themselves, what is causing the .02v line loss/voltage drop....)

The sleuthing continues.
New starter battery on deck soon.

Edit/addendum:
If there's any tips or resources anyone might share / point to, with respect to tracing/diagnosing "line loss / voltage drop" in a branch of a circuit, that would be awesome.

[Flux]

I think Greg was on to something very simple there when he mentioned that maybe in taking apart and putting back together your lugs they got a little cleaner. Best thing to do for voltage losses is oversize everything and make sure you have really good contact at your lugs and no unnecessary breaks in your cables. This is much more qualitative, but my experience has taught me that simple things that may be taken for granted are the things that come back to get you.

Because I did my system myself, all the way down to crimping terminal lugs etc, I am very nervous that I made a less then stellar connection or overlooked something. Good news is that thus far, everything seems to be working.

After being stranded more than once in my beater cars when I was a teen, I have always been a stickler for replacing batteries when they are weak.

That being said, go back through the system, trace wires, check connections, look for an chaffing, clean up the lugs and contact points. Kind of a tune-up.

[DCHitt]

Originally Posted by MountainBikeRoamer

I'd like to think that you could just run a second, clean and uninterrupted positive feed wire (of sufficient gauge) alongside the current isolator-to-starter-battery posiitive feed path (much like running a second ground), but intuitively I have concerns that this isn't as cut-and-dried a situation as that. (May upset other circuits that count on that voltage/current to feed through **them** first before reaching the battery. And those components may be, themselves, what is causing the .02v line loss/voltage drop....)

The sleuthing continues.
New starter battery on deck soon.

Edit/addendum:
If there's any tips or resources anyone might share / point to, with respect to tracing/diagnosing "line loss / voltage drop" in a branch of a circuit, that would be awesome.

The heavy wire from the starter battery probably goes directly to the starter for max starter current. You may find that the alternator wire goes to the starter on the way to the battery.

The starter lug might be a good place to clean up.

[MountainBikeRoamer]

Originally Posted by DCHitt

The heavy wire from the starter battery probably goes directly to the starter for max starter current. You may find that the alternator wire goes to the starter on the way to the battery.

The starter lug might be a good place to clean up.

Hey that helps a lot.

In starting to trace those positive battery lead cables (not easy, since they disappear fast up under the cowl into big looms) --- I noticed what appears to be some sort of small, cylindrical electrical component that's bolted to the radiator core support, and to which one of those heavy positive leads from the starter battery (I think) heads off to. Several other smaller wires run away from this same cylinder, if I recall, as well as another heavy duty (battery cable sized) wire.

My first guess: starter or ignition relay.

Since those are solenoid-based devices (or at least they used to be, in the 1970's Dodges that I've worked on), it has a series of contacts on the inside that could conceivably have developed less-than-ideal connections over time. They score up with carbon / oxidation from repeated cyclings.

So just now went looking....and found this unit on Rockauto.com, which indeed looks like what I'm seeing under the hood.

Ignition Starter Relay - 1995 Ford E250 5.8L
More Information for AIRTEX/WELLS 1M1090

Being the starter relay, I realize that it only sees voltage at its major terminals temporarily (when starting the van), so it shouldn't impact the line voltage when the van is up and running. For a voltage drop at a relay, the dedicated, separate ignition relay component would be more of a likely culprit. Haven't located that little bugger yet, but I'll keep hunting.

Seems once you find/identify these devices, you can test for voltage loss across those directly as well.