Van suddenly drawing power from aux batteries (battery light on)

[ginga]

:huh:  So yeah, I have not had for months now any problems with flipping my switch up in the front to charge my auxiliary batteries. I have watched from my inverter and from my ammeter, when it was functioning that I was charging my auxiliary batteries at the normal voltage that they should be charging. Today while driving perhaps I made a mistake  while driving through the mountains, I noticed my battery light came on and what is happening now is my battery gauge in the car dips down which I have never seen it do when I use my headlights or air conditioning. Turning my inverter on with the connection bridged I see the voltage drop (on the inverter)when I use any of my vans services. I do not see the cars battery gauge slowly drop, it only drops when I initiate one of the vans services i.e. the air conditioner.

 In short does anybody have any inkling as what may have caused my van to suddenly be drawing power while running from my auxiliary bank rather than the house battery?

 

[SternWake]

Your alternator might be failing. Sometimes when they fail they first lose 1/3 of their capacity, then 2/3.


What is the voltage when the BATT light comes on?

 

[ginga]

Your alternator might be failing. Sometimes when they fail they first lose 1/3 of their capacity, then 2/3.


What is the voltage when the BATT light comes on?

I agree.  I believe it is failing.  I can't be 100% on the voltage but from 18-8 on the dash gauge it drops down to about 11 or 10 when the lights are on.  Midrange when they are off, and it returns to normal when I bridge the connection to the aux batteries.  The inverter says 12.5 when isolated and it drops to 12.2 whenever connected.  It's a Ford, so hopefully a mechanic will have no prob replacing replacing the alternator

 

[SternWake]

Not sure how you wired your system up but check the main starter battery to engine ground cable, and connections at the battery.
Usually a Batt light is indicative of a charging system failure, but it could be the voltage regulator or the wiring/cabling to from the alternator or voltage regulator.

I am not familiar with Ford, but perhaps others here are, so it would be wise to post the year, and perhaps go onto rock Auto and do some part pricing. If you do not have far to drive and can charge the batteries by other methods you should not have to be at the mercy of a greedily grinning mechanic and have time to find merely a smiling one.

 

[ginga]

Not sure how you wired your system up but check the main starter battery to engine ground cable, and connections at the battery.
Usually a Batt light is indicative of a charging system failure, but it could be the voltage regulator or the wiring/cabling to from the alternator or voltage regulator.

I am not familiar with Ford, but perhaps others here are, so it would be wise to post the year, and perhaps go onto rock Auto and do some part pricing.  If you do not have far to drive and can charge the batteries by other methods you should not have to be at the mercy of a greedily grinning mechanic and have time to find merely a smiling one.

It's a 98 Ford Econoline E150.  I'm posted up for the night literally right next to an OReillys so in the morning I will get some of my system tested out and run my codes.  If possible I'll buy a new alternator and bring it to the mechanic.  I've had other mechanics tell me most of all fords use the same parts so hopefully it won't never a big issue.  Glad I could make it to town for the night.

 

[John61CT]

Also a really shot battery could be sucking voltage down, get those checked while you're at it?

 

[SternWake]

http://www.rockauto.com/en/catalog/...440640,electrical,alternator+/+generator,2412

Looks like there is a 95 amp and 130 amp alternator available. prices range from 90 upto 280+ on rockauto

They likely sell reman'd alternators at Oreilly.

One thing about many new/remanufactured alternators, they might not take kindly to being asked for a lot of amperage before the brushes get a chance to break into the commutator. Many will say to ensure that the battery is fully charged before starting engine, as a fully charged battery will not ask for much juice for very long, but a depleted battery will. I'd hope a mechanic would throuw your engine battery onto a charger while they remove alternator, if that indeed proves to be the issue.

Oreilleys can physically test alternators, but externally. Otherwise they will just do voltage checks with engine running.

I have a lifetime waranty on an Alternator I bought from Kragen in 04 or 05. Oreillys honored the warranty and Handed me a Wilson remanufactured alternator last time with no paperwork or $ changing hands. Took a few days for it to arrive though.

 

[user 37446]

If you get an alternator, be advised that Ford uses both a 3G small case and 3G large case ones, the stock is a single bridge rectifier. I've read that if you have the room move up to a large case and a dual bridge rectifier if its within your budget. Just info.

From: alternatorparts.com

[font='Helvetica Neue', Helvetica, Arial, sans-serif]"The NEW! Quick Start [/font][font='Helvetica Neue', Helvetica, Arial, sans-serif]Heavy Duty Large Case (left side of photo) [/font][font='Helvetica Neue', Helvetica, Arial, sans-serif]. Ford Motorcraft 3G type alternator for Ford family of vehicles and other adapted applications. Upgrade your small case (shown on right) 2G and 3G Ford, Lincoln, Mercury internal regulator alternator to the Large Case style alternator. If you are currently using your charging system to it's max, then YOU MUST HAVE THIS ALTERNATOR! The 3G series alternator was mostly used from 1992-2000 with some vehicles such as the E series van using the 3G up to 2010. If you are not sure if your Ford Family of vehicles has the 3G call [/font][font='Helvetica Neue', Helvetica, Arial, sans-serif]616-606-5045 [/font][font='Helvetica Neue', Helvetica, Arial, sans-serif]and we can look you vehicle up in our application guide and tell you what series alternator you have."[/font]

[font='Helvetica Neue', Helvetica, Arial, sans-serif]End of quote[/font]


O'Reilleys has for the 1998 4.6 or 5.4 motor, a new (not rebuilt) "Ultimate" brand  95 amp standard for $168, a motocraft 115 amp ($274) and a new "Ultimate" 130 amp optional for $182. Remanufactured is about 20-25% less.

 

[ginga]

Thanks for all the help guys. I've gotten a new 130 amp alternator with a lifetime warranty and I've scheduled myself at a mechanic to swap them tomorrow. Hopefully he doesn't charge me an obscene amount just for the labor because it's really not that hard to do, I just don't have the tools and I haven't done it before myself.

 

[Weight]

A new alternator is not a bad thing. But I do hope you get a diagnosis to be sure of the problem.

 

[caretaker]

yeah, have the mech. put your starting batt on a charger, maybe if its low ask him if you can hang around until its charged up could save you some bucks shortly down the road.