Surpower Isolator problem

[Lenny]

My question is what would cause the isolator (Surepower 12023A) to stop charging my starting battery but still charge my house batteries.

Now if I give the starting battery a quick charge while still in vehicle it starts charging again.
This happened with the last 12023A I had for about 8 years and the one I have in now which is only 2years old.

I won't buy another one and will most likely spend the money and go another route.
Just curious why this happened and if anyone else had the same problem.


Thanks ~ Lenny



06 E250 5.4L 120 amp alt.

2 optima D34's house batteries

1 D34 starting.

[gahamby]

Start here. https://www.sportsmobileforum.com/forums/f20/
Here in particular:
https://www.sportsmobileforum.com/fo...ches-7991.html

I had the same problem with a '07 Superpower. There get arced out inside and stop making contact. Get yourself a Blue Sea isolator.

[Lenny]

Thanks, I'm familiar with that thread and it's a good informative one.

I guess what I'm trying to find out is why would just one side (starting battery) of the isolator shut down and then revive itself later with a charge.
Just don't make sense, and it happened the same way twice.
I would think it would just crap out and be done with.

Is something to do with the diodes and how they react to whatever?

[Scalf77]

I would suspect bad connections, before I suspected the isolator. The instructions for testing the isolator have been inserted in a couple of threads on the topic, relatively easy to bench test.

-greg

[daveb]

The Surepower 12023A is an isolator not a separator. It taps off the alternator charge circuit & only charges your house battery system. That sounds like it is working correctly. If your starting battery is not being charged you have an issue with something else. Check your starting battery (it may be bad or have a bad cell), & the connections from the alternator to the starting battery. Sometimes the battery posts may just be corroded.

[Lenny]

OK thanks. Guess I'll have to go over all the connections from the isolator to the battery and see if it happens again. If that don't do it then just replace it.

[daveb]

Originally Posted by Lenny

OK thanks. Guess I'll have to go over all the connections from the isolator to the battery and see if it happens again. If that don't do it then just replace it.

If I'm reading your post correctly the isolator basically has nothing to do with your starting battery... plus you posted the house battery is being charged. What also you would need to check is to make sure there isn't some kind of unwanted draw off the starting battery that slowly discharges the battery. Yes the isolator can fail but being the house battery is charging normally I'd start off with the easy stuff first. Just pull the starting battery leads and make sure the posts are clean, tight, and use some electrical connection compound. Stick a car charger on the starting battery and charge it up, then reconnect it and see what happens. While charging the amperage should drop to about an amp once the battery is full. If not you might have a cell going bad in the starting battery.


On the good side of things, you probably don't have any issues with the alternator or isolator because the house battery is being charged. The alternator charging wire going to the starting battery is usually smaller than the battery cables going to the vehicles starter and you should check those connections. Not sure about where the alternator charge circuit is connected to the starting system as it depends on the vehicle...some go directly to the battery, some go to the starter, fuse block, starting relay, or a post lug tied into the starting system.

[Lenny]

Thanks for the help daveb.
Maybe I'm not making myself clear but this might help explain my problem.


Motor off - house 12.6v starting battery 12.6v plus or minus .2
Motor running- house 13.5v starting " 13.5v plus minus .2
Alternator - 14.31v (checked at the isolator and battery)


On the road the battery light goes on. I check with a multi meter at the Alt. terminal on the isolator, 14.3 or so.
I check the house battery isolator terminal 13.5 or so.
I check the starting battery isolator terminal and it's not charging low12V.
most likely back feed from battery.
I checked the battery itself and it's the same, not charging.

I shut down and give the battery (at the battery terminal) a quick boost and walla...good to go and battery charging and soon back to 12.6v.


This happened about 5years ago on the first Isolator and it was fine from there on out.


I replaced it about a year ago (same 12023A) not because it failed again but because it was already 7 or 8 years old I just thought it would be good to do.
The new one (12023A) is a little more then a year old and the same thing happened last week....Same scenario : (


After the charge It's fine and for all I know it might be for another 5 years. I even called Surepower and the tech. said if anything,it would crap out al together and not bounce back (which makes sense)


My original question is...before i toss this one out and buy a Blue Sea or what ever, has it ever happened to anyone here.


In any event I will check all wiring and grounds and connections from the isolator to battery and maybe come up with something but I think the problem is with these isolators.


thanks again for all your suggestions, Lenny

[Scalf77]

I can't find the original PDF, but this is a copy of the instructions to test a isolator. I agree your measurements indicate that the isolator is not working. I do believe that you are being misled in to thinking that it is working again based on the higher measurement after charging the the starter. I would agree with the surepower tech, once bad the diode bad, not likely to come back.

There are no moving parts with the diode based devices, no relay contacts to get pitted or dirty, or cycle life. I have seen 20 year old isolators working just fine. The fact that you are seeing the same problem would make me wonder what other issue is making the isolator go bad. Are there any loads on your start side that may be to large for 120 amp isolator?

Certainly moving to a Blue Sea ACR would be a good choice, it would entail putting original alt to start back as stock, and probably larger wire for the house side



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".
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".
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.
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.

-greg

[daveb]

Originally Posted by Lenny

Motor off - house 12.6v starting battery 12.6v plus or minus .2
Motor running- house 13.5v starting " 13.5v plus minus .2
Alternator - 14.31v (checked at the isolator and battery)

I'm not sure how your system is configured but this is what I would expect to see on a typical system. Obviously the voltages might vary depending on several factors including the alternator output, wire size and voltage drops. It will be interesting what you find.