48 replies to this topic

[smlobx]

Ron-
Let me add another possible item to look into.
I have a 2006 F-350 diesel with two batteries and was having issues with the truck's FICM not running smoothly. In looking into it more I found that Ford installs 110 amp alternators in their diesels...the same one they use in the Fusion!!
I had the alternator tested and confirmed that it wasn't putting out the needed amperage and upgraded it to a 175 amp alternator as well as upgrading the wiring from the alternator to the batteries.
The truck starts quickly and the batteries are much happier now...

[Ronanmd1]

Guys - I am finally home from my road trip and plan to investigate this charging issue a bit more next week.  Some observations after playing around with my voltmeter this weekend.

 

1. Truck engine battery voltage at idle = 13.9 V (I get this same voltage along the circuit as far as the connection at the bulkhead where the wires then go under the frame of the truck - I plan to test across the plug in the box of the truck this week)

 

2. Camper battery voltage at idle (with power shut off to camper) = 13.6 V (this voltage drop seems comparable to some posts on the forum and is probably related to the size 10 gauge wire running a relatively long distance from the engine compartment to the camper battery box - provided I don't find a problem at the plug in the box when I lift out the camper).

 

3. Camper battery voltage at idle drops substantially as the camper is powered on and various electrical components are turned on:

 - Fridge power immediately drops voltage at camper battery and isolator to 13.2 V

 - Each of my 2 fluorescent lights then drops another .2 V

 - Stereo drops it another .1 V

 

In a matter of seconds the camper battery is reading 12.9 V (despite the voltage at my engine battery maintaining a constant 13.9 V the whole time), which is very close to the 'disconnect' voltage for the isolator.  These readings with a relatively fully battery.  After one or two nights of camp my baseline voltages would be significantly below these values.  When I am camping and traveling on the road the fridge stays on, hence lowering the voltage in the camper further.  I imagine that this would cause the isolator to nearly always see voltages at or below its disconnect threshold and is probably why the truck never seems to be able to provide the amps to charge the batteries...

 

So 2 questions:

 

1. Am I correct in assuming that this problem could be at least partially fixed by increasing the wire gauge to those recommended on the Sure Power product monograph (they recommend 6 gauge wire for 10-20 feet which is likely close to the length of wire in my truck).  Would this allow the amperage provided by the alternator to overcome the load in the camper?  Or would the isolator still see the lowered battery voltage in the camper and prevent charging despite increased current?

 

2. Since the isolator looks at both sides of the circuit and shuts off if either one of the batteries (camper or engine) drop to 12.4-12.9 V, the isolator seems to be constantly preventing my batteries from charging (or at least doing so ineffectively).  Why not replace this isolator with a dual battery monitor system and split charger such as those by National Luna or Britpart where the 'sensed' on and off voltages are read from the truck battery and not the drained camper battery?  Wouldn't this allow the truck to do the work immediately? Or would the increased load on the alternator be a problem?

 

As an aside, I plan on upgrading my solar as well, but figured I would tackle one part of the system at a time.

Sorry for all the questions....I am learning all the time.  Thanks again guys,

Jason

[Bigfoot Dave]

Have you tried bypassing the isolator. If there are diodes in the isolator they could be the cause of some voltage drop. The first thing I add to a camper or a boat is a Trimetric meter from Bogart Engineering. This gives me a much better picture of my 12V usage as well as battery charge condition. Bogart now has a solar controller(SC2030) that works in conjunction with the Trimetric meter(RV2030). Just setting it up now.

Try Googling "Handy Bob RV". There is a tremendous amount of good information on his site and some of his links. Have patience with Bob and enjoy the read. Another good bunch of information is on "BHA Solar" and their links. Good luck and happy camping, Bigfoot Dave

 

[Ronanmd1]

Thanks Dave - yeah, I am planning on installing the Trimetric system.  I am up here in Canada.  I will need to figure out who can do the install.  None of our local RV shops are too interested.  Might plan a trip down to the northwestern US and coordinate a purchase and install at a shop more familiar with the equipment as part of the trip.  

Jason

[camelracer]

I may be incorrect but my understanding was that the separator only monitored the voltage on the truck side. This could still be a problem if the camper is drawing enough current to cause the voltage at the input to the separator to drop below the turn on point due to the wiring resistance.

 

I solved this problem by moving the separator to the firewall near the battery so there's only about a foot of wire between the truck battery and separator. I know the manual says not to mount the separator in the engine compartment but I've been running it like this for almost 9 years without a problem. I did mount it on the left side of the firewall away from the exhaust and turbo to keep it a little cooler.

[Ronanmd1]

Camelracer - Yeah, that was what I thought until I read the product monograph more closely.  Moving that isolator closer to the battery in the engine may solve the current issue (and hence the voltage drop) if that is the source of the problem.  Good idea.  

[Ethergore]

I may be incorrect but my understanding was that the separator only monitored the voltage on the truck side. This could still be a problem if the camper is drawing enough current to cause the voltage at the input to the separator to drop below the turn on point due to the wiring resistance.

 

I solved this problem by moving the separator to the firewall near the battery so there's only about a foot of wire between the truck battery and separator. I know the manual says not to mount the separator in the engine compartment but I've been running it like this for almost 9 years without a problem. I did mount it on the left side of the firewall away from the exhaust and turbo to keep it a little cooler.

This seems like a great idea but you will still lose some charging potential. I'm having the same problem described in this post and I am planning on just adding a second 10 gauge wire. I am not sure what gauge that would be equivalent to but I am hoping it will keep my voltage high enough to stop the separator from separating. If that does not solve the problem I plan on changing to a solenoid like the old school campers used.

[Ronanmd1]

Ethergore. In addition to moving the isolator, I am going to take the time to replace the wiring with 6 gauge wire. That's what the monograph called for given the longer distance from my engine to the camper battery. I hope that will solve my problem. I will keep you posted

[Ethergore]

Ron- If it's recommended to not put the separator in the engine bay maybe you should just do the wire sizing first. Just a suggestion.

[Ronanmd1]

Yeah - not sure.  I figured I would do as you did and keep it up at the firewall.  The monograph says do not mount in direct engine heat...hmmm  will see how it looks tomorrow when I get under the bonnet

 

J