Hooking up a battery isolator

Well hello all ... I'm working on setting up a battery isolator in my 2006 . I spent an hour or so running the wire from my alternator to my isolator and then from my isolator to my battery . I was impressed with my work till I turned on the engine and noticed the alternator warning light was on . damn it Jim I'm not an engineer (yet) . anyway I'm not sure what the hang up is and why I'm having this issue .if anyone has done an isolator I sure would appreciate some info on how they set it up .
I did get the noco ssd 140 amp isolator. I figured it was the good one so grabbed it .

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First, you have to tell/show us *how* you hooked it up.

Where did you get the isolator's coil power from?

Where did you attach to the alternator?
(and, why didn't you just use a tap on the starter battery's PDC?
(drawings and/or photos to verify that what you did is what you drew/intended)

"Doctor? I hurt! Why?" ... requires a lot more data....

--dick
p.s. as a pure guess, since you were (reportedly) messing around at the alternator itself, you screwed up affected the DF connection somehow.
(i.e. the little wire, not the big one)

I did end up taking it all apart and outing it back to original and the light went out. So I didn't mess up the alternator .

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You could do it correctly. There is no need to connect to the alternator. Do you want to be able to use the aux battery to jump start the main battery if you left the headlights on?
If so, you'll need at least 6 to 4 gauge wire
A line from the start battery to the relay, a line from the relay to the aux battery and a connection to D+ to trigger the relay is all you need. The D+ is available under the driver's seat.
These helped me:

Wiring the aux battery- T1N_Retrofit_Aux_Battery View attachment T1N_Retrofit_Aux_Battery.pdf
Body builder information that shows the connections under the seat. View attachment body builder.pdf

Update: OK I see your picture. The A connection can be fed the D+ circuit available under the seat.
I didn't like the voltage drop of the type of isolator you have. I used a standard relay, looks like in an old Ford. I'm losing 0.1v for the distance of the wire run. I didn't want to lose more in the isolator.

I have a deep cycle battery I want hooked up to run my electronics while im camping . but don't want it to drain my main battery that's why I'm using the isolator . it's supposed to isolate the secondary battery when I turn the key off. From what I understand . the last thing I want is to watch movies all night then not be able to start the car in the morning

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I'm going to have to respectfully disagree with ECU... i think the "A" connection needs to be at the starter battery's positive post (or on the PDC fuse block that's attached there).
It's the input for the charging current for the (two shown) auxiliary batteries.

The D+ connection under the seat is only good for 30 amps (fused)

--dick (who'll go look up the isolator's spec sheet and may change this opinion in an hour)

Fascinating.... let me start by quoting from a Sure Power Isolator manual:

SurePower said:

If application is a Dodge Sprinter using the Bosch alternator, a battery isolator is not compatible. Use of a Battery Separator is recommended (verify alternator size in amps), see group 4

Click to expand...

So the Sprinter (they don't mention which years... the T1N and NCV3 alternators have different control mechanisms) is not compatible with a diode isolator.

You need to use a relay battery separator.

The Sprinter does not like having the alternator separated from the starter battery by the isolator diode's forward voltage drop (and possibly its blockage of reverse current).

Here Be Drawing: Top section is "unmodified Sprinter",
Middle section is what (i think) you did.
Bottom section is how it should be done (see footnote).



What i think is really happening is that the Instrument Cluster (which controls the DF lead) "knows" the Alternator too well.... it activates the DF and expects *specific* behavior by the alternator. The Isolator's diodes subtract some of the alternator's voltage output, and the Instrument Cluster (or ECU) notice that and declare a fault (by lighting the alternator light). ((that thesis is making a guess about the internal "smarts" of the IC, but the logic is similar to what happens with the turbo.. if the ECU sees less turbo output than it's expecting, it stops trying to use it and turns on the ECU light (sometimes).

So: instead of the semiconductor isolator, get a "real relay" battery separator, and do what the third section of the diagram shows. Here is the service manual's view of it:



--dick
footnote: i didn't ever think you'd messed up the alternator, merely loosened (or something similar) the DF control lead.
(in fact, i sincerely thank you for running this experiment )

Really good info here for setting up a 02-06 dual battery with an isolator OEM style. Not to useful for you i think.

http://www.sprinterparts.net/pdf/retrobat.pdf


Sent from the first city on the Mississippi.

I wholeheartedly disagree with Auto. the A connection is to tell the relay that the alternator is running, just a signal. This is THE SAME as the D+ circuit that comes on when the alternator is up and spinning. The A feed is NOT 30 amps nor a load. It receives 12 volts when the alternator is functioning to tell the isolator it is OK to connect. The D+ line is this exact same feed through relays and such so that you don't screw with the alternator.
Connection the start battery to the isolator does NOT put the isolator between the start battery and anything else in the system. It only isolates it from the connection at the other end of the isolator, the one that feeds the aux battery.
Look at the T1N_Retrofit_Aux_Battery.pdf and replace your isolator for the relay in the diagram.

ECU said:

I wholeheartedly disagree with Auto. the A connection is to tell the relay that the alternator is running, just a signal. This is THE SAME as the D+ circuit that comes on when the alternator is up and spinning.

Click to expand...

That's all true for a relay isolator.
But:
If you look at the hook-up diagrams for the unit he has, the *only* input current is through the "A" terminal. It's (almost) a pure diode isolator. The instructions for his unit explicitly say to remove the original alternator-to-battery connection.

The A feed is NOT 30 amps nor a load. It receives 12 volts when the alternator is functioning to tell the isolator it is OK to connect. The D+ line is this exact same feed through relays and such so that you don't screw with the alternator.
Connection the start battery to the isolator does NOT put the isolator between the start battery and anything else in the system. It only isolates it from the connection at the other end of the isolator, the one that feeds the aux battery.
Look at the T1N_Retrofit_Aux_Battery.pdf and replace your isolator for the relay in the diagram.
View attachment 78409

Click to expand...

...which is actually what i thought he was doing (with the odd tweak of tying to the alternator instead of the battery post) before he posted his photo of the instructions (and the model name/number).

Your re-twiddled version of my 2nd drawing is what my 3rd drawing is trying to show. (are your diodes just for arc suppression?)

For your drawing to be useful, how do you equate/convert his "A, DE, B1, B2" to your A, C, DF?
(his unit uses the DE terminal for "Delcotron" alternators, which the pdf file i referenced also covers.)
(the "DE" terminal is where you tell the isolator that the alternator is running, but it's an optional connection)

What you're picturing (and what he should really have) is something like one of Blue Seas' Automatic Charging Relays.
Or this $43 Stinger relay.
(or the MB relay)

--dick
p.s. as a side note... notice how *large* the NOCO unit is... that's because it gets hot due to the power loss through the diodes. The simple relays are much much smaller and don't generate anything near the diode isolator's losses.

I can certainly say that the diagrams you provided make no sense. Maybe the isolator will charge whichever battery that is low. Also I don't think those isolators work as a jump battery. I agree that they are a suck on the system and that a simple relay is all that is needed.

Well i t kinda makes sense what dick says . because we just tried to hook it up again with shorter wires and it did the same thing. And I know the isolator is good. So the sprinter being touchy seems like good logic

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ECU said:

I can certainly say that the diagrams you provided make no sense.

Click to expand...

If you can't understand them (and they were drawn quickly), then other folks might be confused, too... could you please highlight what's puzzling?

Maybe the isolator will charge whichever battery that is low.

Click to expand...

Correct... the problem with the Sprinter is that it apparently doesn't like the diode drop.
On an old car (or a Ford, for example) the diode isolator would work.

Also I don't think those isolators work as a jump battery.

Click to expand...

Also correct

I agree that they are a suck on the system and that a simple relay is all that is needed.

Click to expand...

Also correct ... diode isolators are a relatively inexpensive way to charge two batteries from a single simplistic current source (i.e. alternator). If the alternator cares about the battery voltage, it's not seeing the correct value due to the isolator's diode drop.

The diode isolator's one claim to fame is that it does not require a control wire... it just splits the alternator current to the two batteries, with the lowest battery getting the most current.

Relay isolators require something else (the D+ signal, for example) to tell them when to join the batteries. Snazzy ones (magnetic latching, voltage-sensitive, etc) add other features.

--dick

autostaretx said:

If you can't understand them (and they were drawn quickly), then other folks might be confused, too... could you please highlight what's puzzling?

--dick

Click to expand...

I understand your drawings. But that PDF from the company didn't seem like an isolator. It behaves like a dual charger.
Back to helping the OP. Maybe he wants to eventually get a solar package. I have no experience there. But don't they have special isolator/charging devices?

I'm doing a light build out for someone (write up with pics to come...), and I opted for the simple Stinger solenoid isolator. Connects as shown in picture. I haven't tried it yet because I'm still wiring in all the AC outlets and such.

The PO did a typical DIY build, OK in concept but so-so in execution. New owner didn't want the shower/toilet/sink. I basically tore everything out and started over. He put in a Dometic roof air conditioner, that needs 20 amps 120vac. So, he has a 3000 watt inverter and two deep cycle batteries. The charge was manually controlled with a off/charge/shore switch, which of course resulted in the batteries never getting charged and then running down. I'm replacing that charging system with the solenoid activated by the D+. I also installed a 1 hour mechanical rotary timer inline for the roof AC, so they don't park somewhere and forget to turn it off and then drain the batteries. I don't think it will get used very much, though.

ECU said:

I understand your drawings. But that PDF from the company didn't seem like an isolator. It behaves like a dual charger.

Click to expand...

Perhaps we're suffering "looseness of terms", but the Sure Power page certainly calls itself Isolator instructions across the top.

(preamble note/warning: the following is NOT SUITABLE FOR SPRINTERS)

As i understand the terminology, this is the (idealized, simplified) diagram of a "Dual Charger":
two sources of power (alternators), one battery getting charged by whomever's running.



Whereas this is the (idealized, simplified) diagram of a "Diode Isolator" (labeled to match BlownGlass' Noco device):
One alternator feeding two batteries: (and this matches the Sure Power page's diagrams: one alternator)



Finally (just to be confusingly complete) it is feasible to meld the two into one "dual chargers to multiple batteries" system.
(you'll have to imagine that i drew the four diodes (as above) inside the boxes).



What i liked about the Sure Power sheet is that it also showed (in detail) what the other possible hookups are for various other brands of alternators. ((The "Delcotron" systems are pretty weird... there are two alternator models made with the same physical alternator casings... but they're totally incompatible with how they handle the DE (or CS) wire. (discovered reading other sites looking specifically for what-the- are they??)))

Does this help clear things up?

--dick
p.s. in Ye Olden Days the car's voltage regulator was (functionally) attached to the *battery*, it wasn't hidden inside the alternator.
In those cars diode isolators worked because the regulator would see the effect of the stolen 0.6 volts, and would increase the generator/alternator's output accordingly. In the Sprinter (and some others), the voltage regulator is inside the alternator and does NOT expect (nor account for) the stolen 0.6v ... and thus diode isolators create confusion (or, in some cars, smokes the alternator...).

I installed one of these:

http://sterling-power.com/collectio...cts/alternator-to-battery-chargers-up-to-130a

which also is placed between the alternator and the battery. As far as I understand it, there is a diode between the alternator and the starting battery, and even if the unit fails, should be able to continue to charge the starting battery. So from the perspective of the Sprinter (assuming the same forward voltage) it should be identical. It works fine for me.

However, it did not work initially - I had to provide an additional connection to the "ignition on" terminal from the upfitter's box under the seat to the unit, which passes the signal along to the alternator to start it up. I got an alternator light as well until connecting this. Perhaps what you need to do is simply connect that to the alternator. Here's the manual:

https://cdn.shopify.com/s/files/1/0658/7343/files/AB12130.pdf?477

"Ignition feed/ Starter solenoid: Some alternators will not fire up without a
voltage on their B+ terminal. Because the alternator-to-battery charger contains a
split charge diode there will be no voltage feed on the B+ terminal which means that
the engine will start but the alternator may not work. If this is the case, then simply
connect a ignition feed ( from the key switch ) which becomes live when the engine
is started. this will feed 12 v through the unit and fire up the alt"

It's a little ambiguous in the wording because it says "through the unit" so I'm not certain that it is anything more than a direct connection to the alternator output terminal.

I can test continuity and see if it's just a simple connection to the alternator when I get a chance...

smrl said:

I installed one of these:

http://sterling-power.com/collectio...cts/alternator-to-battery-chargers-up-to-130a

which also is placed between the alternator and the battery. As far as I understand it, there is a diode between the alternator and the starting battery, and even if the unit fails, should be able to continue to charge the starting battery. So from the perspective of the Sprinter (assuming the same forward voltage) it should be identical. It works fine for me.

However, it did not work initially - I had to provide an additional connection to the "ignition on" terminal from the upfitter's box under the seat to the unit, which passes the signal along to the alternator to start it up. I got an alternator light as well until connecting this. Perhaps what you need to do is simply connect that to the alternator. Here's the manual:

https://cdn.shopify.com/s/files/1/0658/7343/files/AB12130.pdf?477

"Ignition feed/ Starter solenoid: Some alternators will not fire up without a
voltage on their B+ terminal. Because the alternator-to-battery charger contains a
split charge diode there will be no voltage feed on the B+ terminal which means that
the engine will start but the alternator may not work. If this is the case, then simply
connect a ignition feed ( from the key switch ) which becomes live when the engine
is started. this will feed 12 v through the unit and fire up the alt"

It's a little ambiguous in the wording because it says "through the unit" so I'm not certain that it is anything more than a direct connection to the alternator output terminal.

I can test continuity and see if it's just a simple connection to the alternator when I get a chance...

Click to expand...

Well that is interesting I will look into this . thanks

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