New alternator. DC to DC breaker issue.

[posplayr]

The "signal wire" as you call it is to tell the DC-to-DC that you are running a "Smart" Alternator via the ACC connection. You are not, so you do not want that connected.

EDIT 9:29AM

I see Scalf77 was posting while I was composing and he clarified the operation better than the manual and after rereading i need to correct what i posted earlier by just greying out my erroneous statements.

The manual is a little confusing but it seems that the Start Bat to Aux Bat charging portion of the DC to DC will not charge unless the ACC wire is high.

The AP40DC describes an ACC line which is really the +12V RUN signal rather than a having the ignition key in the accessory positon which is when the engine is not running.

So the AP40DC ACC wire is essentially the D+ wire on the Renogy DC-DC charger which can be controlled by the wires to the smart alternator, or just +12V RUN.

For a 40 amp DC to DC the standard recommendation is 6 AWG wire for up to about 10-15 feet. This will restrict the Start battery current to 50 amps in order to deliver 40 amps to the aux battery.

If connecting between batteries, standard practice is to put a fuse as close to the batteries as practical. However, with my 1997-2011 Econolines, the battery is already separated by fusing from the alternator so you can connect the DC to DC directly to the alternator (using a local mounting bolt for ground)without a fuse and the 6 AWG cabling.


In my 2002 E-250, I mounted a 5K BTU 12V Rooftop AC along with a pair of 150 amp-hr AGM's. The AC is connected directly to the AUX battery pair along with a 120VAC invertor. I had trouble meeting the demand for the AGM charging and 12V rooftop A/C demand. It seems I have it solved right now by dropping the DC-DC chargers completely and just using a 120Amp battery combiner relay. Victron also makes a lithium version.

https://www.amazon.com/gp/product/B071Y7C9MM/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

The alternator is rated at 300 amps and was able to deliver 80-100+ amps to the Aux battery/AC combination as well as 15 amps to the vehicle while maintaining 14+ volts at idle. After about 5 minutes of running, the alternate got warm but not excessively. I did not have my IR gun handy so no temperatures are available till I get setup again. However, the alternator is smart in some respects.

This Is Truly A High Amp Premium Quality Well Built Alternator
It Has OE compliant functions : current limiting, thermal shutdown,
load dump protection, shorted field & lamp circuit protection​

https://www.ebay.com/itm/202513986004


This vendor has other alternators for different model years but I have not found one for the 1992 E-250 4.9L or my own 1990 F-150 4.9L.

 

[dbhost]

I am starting to think ground issue. I tried charging via the converter / charger yetsterday and was failing at that.

It is incredibly stormy today and will be well into the weekend.

I have checked the cabling running into the charge circuit and we are dealing with 4ga coming from the battery to the DC to DC charger, and 4ga to ground.

I never did set up the buss bar for ground on this thing. I think I will reconfigure this so I can run 4ga to the ground / bar, then chargers (DC to DC and converter charger) as well as the battery itself and the fuse panel can ground to the chassis ground

My setup is.

150 amp Ford 3G alternator. (OEM alternator lists as 80 amps) (PowerMaster 7761), Halfway wondering if I should have gone with a Powermaster 477711 200 amp alternator) https://www.summitracing.com/parts/PWM-7761 The small case 3G did NOT fit my van, at some point, likely at the Sportsmobile factory they swapped for a large case 3G bracket setup from an F series truckand a larger alternator...

Removed Sportsmobiles 45 amp battery isolator, installed Red Wolf 60 amp breaker https://amzn.to/40qamiq this has some odd rattling in it, replaced with a Zookito but still not great...

Cable measures out to be I believe 4awg. Should be sufficiently large enough for the application.

AtemPower 40 amp DC to DC charger with MPPT charge controller and LiFePO4 profiles. https://amzn.to/4hrQkds

PowerMax PM3-45 45 amp Converter Charger. https://amzn.to/3AcylHs

Chins 400 amp hour 12v LifePo4 battery with bluetooth smart BMS. https://amzn.to/3YKzvDd

The DC to DC charger is installed in line in the elecctrical compartment instead of under hood, didn't want to expose it to moisture. The solar side of it goes to an anderson connector that leads outside of the van.

 

[posplayr]

I am starting to think ground issue. I tried charging via the converter / charger yetsterday and was failing at that.

To see what is going on you really need a clamp on amp meter. :d8:


I wired one of these into the dash

https://www.amazon.com/gp/product/B0BFJ5NV5L/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

As well as one of these.

https://www.amazon.com/dp/B091YXN1YP?ref=ppx_yo2ov_dt_b_fed_asin_title

alternatively, you can get one of these.

https://www.amazon.com/dp/B077XDHQNR?ref=ppx_yo2ov_dt_b_fed_asin_title


So I have 6 awg cables from the alternator to the batteries (300 amp-hr AGM) about mid ship on drivers side. The amp meter uses dedicated AGM voltage/ground whereas the dual voltage gauge uses dedicated alternator sense 12V/ground. There is a two-three 1/10ths difference using the alternator ground (higher) vs the midship AGM (lower) when pushing current to the AGM's

Also having a dedicated sense at the alternator allows me to measure 14.4-14.5 whereas the cigarette lighter which is always hot circuit barely (if at all) gets to 14V. The AGM's stay in the high 13's when charging at 50-70 amps to the AGM's/12V AC.

 

[dbhost]

So the wiring in the engine compartment is quite straight forward, it is where it snakes around the frame / underneath the van and then ducks up into the vans electrical compartment courtesy of Sportsmobile that is a mystery box to me...

There are a couple of possibilities that I can see as it was working before the shop time...

The biggest of which is the underside of the van was deeply disemboweled, I.E. gas tank removed for a new fuel pump and addition of the dip tube and pump for the Velit heater. Plus mounting of the pump, and wiring for the heater, exhaust etc...

It is possible that the cable for the DC to DC charger suffered some damage to its insualtion in the process, easy enough fix but finding it would be a pain in the tail...

Another possibility is a bit cynical but not out of the realm of possibility, and that is the charger is failing internally and thus pulling too high of an amperage.

Today is a stormy weather day here, so will delay a day or two until it dries up, but will test between battery and alternator with clamp meter.

I have a spare DC to DC charger / MPPT charge controller that was supposed to be fitted to my Pickup for truck camper duty but is just spares now. Might swap them across to test...

Failing that, I will just yank the cabing back, redo it with fresh cable which I have at overkill levels (0 ga) and put some pennies aside for a Renogy 50 amp MPPT charge controller with DC to DC chargning. https://amzn.to/3YNNBnq

However if this is an issue with the alternator pushing too much that won't fix the problem...

 

[posplayr]

However if this is an issue with the alternator pushing too much that won't fix the problem...

The alternator is an imperfect voltage source. It should hit 14.5V if the load is not too high for the RPM you are running. Alas, if either condition (too much current for the RPM you are at) is not met then the voltage will drop corresponding to the current that is delivered.

This is essentially going to be a V_alternator=I_delivered(function of RPM)xR_load relation. For a given load resistance - R_load, the current delivered, I_delivered will be limited by the alternator's RPM, and the alternator output voltage, V_alternator) will drop according to the formula.

Another alternator dependency is how hot it gets. Generally the hotter it is the less current it can deliver which further reduces the output voltage. Other than this, how much current that is demanded is all about the loads and the DC-DC is a big factor in that.

 

[dbhost]

Okay swapped the spare charger / charge controller in it, tested, failed. Put the clamp on meter for amps, never went above 40, popped and the breaker is hot.

Hate to think 2 bad breakers in a row, but going to get a quality breaker and see if it helps, and if I have to I will re-cable it front to back to eliminate the wiring as the problem...

 

[1der]

Just to check off something - check the connectors on the wires -(all ends) for proper continuity. You should also check for resistance in the breaker itself.

 

[posplayr]

Okay swapped the spare charger / charge controller in it, tested, failed. Put the clamp on meter for amps, never went above 40, popped and the breaker is hot.

Hate to think 2 bad breakers in a row, but going to get a quality breaker and see if it helps, and if I have to I will re-cable it front to back to eliminate the wiring as the problem...

If you refer to the diagram you posted before, the recommended Fuse from Start Battery to the charger is 60A and the fuse at the output (to the haus battery is 50 amps).

If you put a 40 amp rated breaker at the input to the DC-DC you will get what you are seeing. I have explained these currents before. The 40 amps is the current limited maximum coming out of the DC to DC to your haus battery (I'm guessing).

 

[dbhost]

If you refer to the diagram you posted before, the recommended Fuse from Start Battery to the charger is 60A and the fuse at the output (to the haus battery is 50 amps).

If you put a 40 amp rated breaker at the input to the DC-DC you will get what you are seeing. I have explained these currents before. The 40 amps is the current limited maximum coming out of the DC to DC to your haus battery (I'm guessing).

60 amp between chassis battery and charger. 50 amp on the output to the coach battery and it never flips, just the one closest to the alternator, and it is a 60 amp...

 

[posplayr]

so how much current is going through the 60 amp fuse? before it flips.

What is the voltage at the input to the DC to DC before the 60 amp fuse trips?

If it happens too fast then add a second fuse braker in parallel so you can see the voltage and current.

The lower the voltage going into the DC to DC the more current it will take.

You can also try and reduce your programmed output voltage to reduce the current demand just to see what is going on before the breaker flips.

 

[Scalf77]

Your data point doesn't make sense, so we kind of need some clarity. I would expect to see more than 40 amps going through the 60 amp breaker. Being that the unit should be putting out 40 amps, it most likely will need more than that on the input. Also a voltage measurement on the input also would be good.

Other things of importance.
need to understand what you are doing with the ACC connection.

State of the charger. We want to make sure that the charger is is bulk (maximum current out) . This is directly related to SOC level of the battery.

Status of the Engine at the time of testing. Example when you first start up the engine will be in fast idle, also for a short period of time you will be replacing current in the starters that was used while cranking engine.

Generally it is best to wait till it idles down to normal idle. This will be the worst case output for the alternator.

Start out with everything on in the van off, no lights, no heater, no air-conditioning. You are going for minimal current usage.

Start taking your current reading before the breaker and voltage at the DC-to-DC input.

If all is well in this state, then you can start turning on things in the van IE headlights. When you do this you want to keep monitoring the voltage. If the voltage goes down, you are reaching the output capacity of the alt for those conditions. As the voltage drops, your current through the breaker will increase.

It could be that the original alternator did not provide enough current and the unit shut down, once the RPM's went back up it was back on and working.

The new alternator may have more capacity and it may not drop below the turn off voltage. So the lower voltage may increase the current enough to trip the breaker.

You just need to get some data give you an idea of what is happening.

 

[dbhost]

So with as much time and effort as I am able to give between cloudbursts, followed the cables as far as I could. The one feeding into the breaker gots into a harness that disappears behind the alternator. I can't get my hand behind it, haven't crawled on the ground to look yet etc... but I am 99% certain it connects to the alternator output...

Measuring voltages out of the alternator there is the cable from the alternator fo the positive side on the battery so at the + terminal shut off I have somehwere around 13v. Didn't pay THAT much attention as that wasn't the important number, just had to be lower than 14.whatever...

Running at idle I am getting 14.33v at the + and chassis ground.

At the inlet of the breaker which is on the short lead from the alternator to the rest of the rig, and again I am reusing Sportsmobile's 1993 wires, I get 13.9v, a 4v drop in less than 2ft!

Next step would be to TEST ONLY, move output connection over to the chassis battery, disconnect the DC anderson connector and measure voltage from the + on the anderson connector to chassis ground... I SERIOUSLY doubt I will be able to measure that wire for resistance without back pulling the entire thing and at that point might as well just run new cable...

 

[dbhost]

... a voltage measurement on the input also would be good.

13.9v, when the chassis battery is getting 14.33 via a separate cable making me suspect the cable...

Other things of importance.
need to understand what you are doing with the ACC connection.

Cut ti free, so not a danged thing. However it WAS wired up to the signal wire for the voltometer from the alternator, if that gets signal, then it is running...

State of the charger. We want to make sure that the charger is is bulk (maximum current out) . This is directly related to SOC level of the battery.

This style of charger is just not that smart to give you that level of data...

Status of the Engine at the time of testing. Example when you first start up the engine will be in fast idle, also for a short period of time you will be replacing current in the starters that was used while cranking engine. ...
Start out with everything on in the van off, no lights, no heater, no air-conditioning. You are going for minimal current usage.

Fresh start, high idle, no fans, no lights no nothing other than engine and DC to DC charger... The breaker typically flips within about 20 - 30 seconds...

Generally it is best to wait till it idles down to normal idle. This will be the worst case output for the alternator.

Unfortunately it flips too quickly...

Start taking your current reading before the breaker and voltage at the DC-to-DC input.

13.9v and TBD... But I know how to get the data, just need a second set of hands.

If all is well in this state, then you can start turning on things in the van IE headlights. When you do this you want to keep monitoring the voltage. If the voltage goes down, you are reaching the output capacity of the alt for those conditions. As the voltage drops, your current through the breaker will increase.

It could be that the original alternator did not provide enough current and the unit shut down, once the RPM's went back up it was back on and working.

The new alternator may have more capacity and it may not drop below the turn off voltage. So the lower voltage may increase the current enough to trip the breaker.

You just need to get some data give you an idea of what is happening.

Like I mentioned, the data I am able to gather underhood isn't promising as far as that cable is concerned. I am getting voltages I expect to the chassis battery, but NOT to the breaker via a secondary cable off the alternator. Need data from the anderson connector at the back...

 

[dbhost]

I should note the wiring I have and what should be here don't match...

My feed comes directly off the alternator, not the coach battery, back charging to the coach battery isn't going to work like this anyway...

Looking for some 6ga in my box o electrical bits and bobs...

 

[1der]

Breaker HOT guys.......:b1:

 

[dbhost]

Okay moved the feed from the alternator to the battery, same effect. Ran out of light so couldn't meter it until tomorrow. Pretty sure I will end up going to Home Depot to grab 15ft of 6ga to get this done.

 

[dbhost]

Breaker HOT guys.......:b1:

Got a new good breaker on the way, strongly suspect the wire is finding ground when it shouldn't...

 

[dbhost]

So I did get out there with the meter (drop light helps). Looks like the 13.9 is just what the alternator is doing at that given time. The engine idles up a touch and alternator output goes to 14.5 and the breaker flips.

Did this 3 times in a row.

 

[dbhost]

Looking at the voltages this is definately a problem with the new alternator. The feed lead for the DC to DC charger did need to be moved for sure, but the voltage regulator should NOT vary voltage output that much, and the alternator MFG (Powermaster) agrees. They are shipping a replacement out on Monday.

 

[1der]

13.9 to 14.5 is the range you were seeing?