Harvey51
Alberta
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I have a 2004 E350 and charging from the alternator no longer fully charges the house batteries - 2/3 on the indicator is all I get after a long drive and a few hours to stabilize. The full light goes on when charging from shore power through the converter, and after disconnecting shore power, it stays on for hours of use. We get a couple of days of power for the fridge and lights when boondocking from the initial shore charge, not so much from an alternator charge.
I calibrated my modestly priced meter last summer to read 1.65 Volts on a brand new duracell battery. This summer it says 1.66 - not much drift! The batteries (still lighting the 2/3 light after a couple days at home from the last trip) read 12.4 V. When I fire up the engine, the voltage at the house batteries goes up to 13.4. At the same time, there is 14.9 V at the engine battery.
Quite a drop from the engine battery to the house battery - is that normal? I don't know where the battery isolator is located or I would check for an abnormal drop there. Is normal about 0.6 V ? I guess a 2004 would have a solid state isolator rather than a relay.
If advice is to get a new isolator, what type is recommended? I see there is hybrid type that uses an electronic circuit to control a heavy relay, reducing the voltage drop to zero.
A little reading suggests that the engine voltage regulator is completely unaware of the state of charge on the batteries, blindly maintaining 13.5 to 14.5 Volts. Would a long drive overcharge and damage house batteries? Maybe that 0.6 V drop at the isolator is a good thing? But the extra 0.6 would increase the charging rate. Perhaps we should hit the battery disconnect switch when driving with already fully charged batteries?
2004 Adventurer (Canadian) 20 footer
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Sloop Smitten
San Marcos, CA
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I can think of two things that might be worth checking.
First is the relay that connects the house battery to the alternator when the engine is running. There could be some faulty contacts there (internal or external) that could cause a slow charge condition on your house batteries.
The other is the condition of the power cable from the same relay to your house batteries and its condition. You may be dropping voltage from some internal corrosion or poor contact surfaces on your connections. You can measure the voltage at the relay where the cable from your house battery connects and at the house battery. They should be within about 100 - 200 mv of each other. If it is more clean the connections and try again. Make sure you also clean the ground connections on your battery.
1992 Fleetwood Jamboree Rallye 24' M/H
Ford E350 Chassis, 7.5L Engine, E40D Transmission
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Cruising Califonia, Sailing the Pacific!
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ScottG
Bothell Wa.
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If you have a diode based isolator it has died which is very common. I would (and did) replace it with a 100% duty cycle solenoid type relay. You can get one from NAPA for about $20 but make sure it has the metal housing and is rated for 100% duty cycle.
Scott, Grace and Wesly
2003 Dodge 3500 4x4, 6 speed Cummins (lightly bombed),
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MrWizard
Traveling
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alernator voltage will go down as the engine and alternator heat up
otherwise your engine/chassis battery would over charge
you probably have a diode based isolator, possibly 75amp rating or less
you need a bigger one that matches your alternator rating
or a "Continuous Duty" relay with 100amp or higher contacts
the last time i replaced a battery relay I installed a forklift relay with 200amp duty contacts
they sell for around $70
* This post was
edited 07/16/12 06:39pm by MrWizard *
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Harvey51
Alberta
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I cannot find the isolator or the relay for the battery disconnect! The wires from the battery go directly out of the battery compartment to a storage compartment containing the converter. There the positive and negative wires (about 12 gauge) Y one into the converter and one into the floor. I cannot find where it goes from there! There is no audible click anywhere when the battery disconnect switch is tripped. The wires into the switch are lighter, maybe 14 gauge. I looked all over under the vehicle and found no wires other than a harness to tail lights and the hitch wiring connector.
I don't know where to start from the other end. Would the wire to the house batteries start from the alternator or would it pass through the fuse box in the engine compartment? Would the isolator be in the engine compartment, perhaps visible from underneath? Ford E350 2004.
Any help most appreciated!
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MEXICOWANDERER
las peñas, michoacan, mexico
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Joined: 06/01/2007
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Most Fords I've seen use fusible links near the engine battery and some kind of an engine solenoid or buss on the fender near the battery. You can spot a non-Ford wire connection pretty quick. It'll take you to what you seek.
The IAR, 3G, 4G, and 6G alternators use Ford's classic three wire voltage regulator connection. The "A" terminal (It's marked on the plastic tang) is the voltage sense lead. Regardless of how you tested your DMM I would be suspicious of the test instrument not being dead on correct, before condemning either the sense lead circuit or voltage regulator. 14.9 is off specification. At 25C the regulator should exhibit 14.4 to 14.5 volts. There should not be more than .2 volt differential between the A terminal and engine battery positive post.
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Harvey51
Alberta
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Thanks for all the ideas! I spent several hours on it today. I thought this thing hiding behind the engine battery was a 3 terminal relay type isolator
but it turned out to be a relay for the engine starter.
I found many wires routed below the driver's doorjam, mostly heading up around the back of the door. I wonder what they are all for!
Near the back underneath the MH there are two packages of wires with connectors leading up through the floor
The unused connector (lower right corner) was for hitch wiring. I couldn't find a mate for that connector so I soldered my own wires on it leading to my hitch connector a while back. Disconnecting the lower connector disabled the clearance, parking and signal lights on the house. Disconnecting the upper one ended the flow of power from the engine to the house. It is the orange wire that carries the engine power straight to the battery disconnect switch (no relay). I got a little more charging voltage by squirting contact cleaner into the connectors.
Here are the wires coming up near the converter - different colors; they must be spliced in the plastic tube. The big black one is connected to the orange wire underneath. The white is a ground wire.
Still no sign of an isolator. I wonder if the house manufacturer just used the Ford wire for power to the hitch connector. Would that circuit have a built-in isolating diode? Any thoughts on where that orange wire originates in the engine compartment? Oh, I must check for a fuse for the hitch connector.
I am disappointed that the power wire is quite small. Looks like perhaps a 12 gauge wire. Yet we have been quite happy with the charging until very recently. I wonder if it would be worth attempting to run a heavier wire with a proper battery isolator?
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Harvey51
Alberta
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Yes, there is a fuse (Auxiliary battery, 60A) and relay (Trailer battery charge relay) in the engine fuse box. I swapped relays in case that one was getting tired but didn't gain any more charging voltage. I'm at 13.8 now, 0.4 up from when I started so maybe the problem is solved! Yes, I know my meter must be reading a little high but the extra 0.4 will surely help. And 60 Amps sounds good enough.
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Sloop Smitten
San Marcos, CA
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Harvey,
The relay you identified as the starter relay only has two connections and should have three. Why do you feel it is a starter relay? If it is I do not see how you could start your engine. I am betting the larger wire on that solenoid goes down to your starter. The other side should be connected to a wire that goes to your house battery or a connection in common with your house battery. That way when you start your engine the solenoid actuates and your alternator will be charging both battery sets. With the engine off the solenoid opens and the two battery sets are isolated. The solenoid looks excactly like the solenoid in my Ford that is used as the battery isolator. Maybe someone bypassed it in the past because it needs to be replaced. I do not think Ford has used that type of relay for the starter in a long time. Starter relays are now usually integral to the starter itself.
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wa8yxm
Wherever I happen to park
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Before spending money on a new isolator or isolator solenoid do this simple test
Take your meter and with the engine running measure the voltage AT THE SOLENOID (or as close to it as possible) both sides, If you get Same/Same, solenoid is good, problem is elsewhere. If you get high/low, Problem isolated. Replace solenoid.
NOTE: If the same same is the Lower voltage, problem is engine wards, if it's the higher, house side.
Nothin adds excitment like something that is none of your business
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