Foretravel Owners' Forum

I recently bought a 1995 U-300 SE that is in beautiful condition.  We were aware that the house batteries are junk and need to be replaced.  But, when I got it home and plugged it in I still have no or very little 12v power for interior lights.  There is a Heart power inverter/charger in the large passthrough storage bay but I can't find the 12v converter anywhere?  Even if the batteries are shot, the 12v converter should still be running all 12v house systems off shore power or generator right?  I also have a Xantrex controller above the door that is showing <10v in the coach and a volt/ammeter that shows 0.00 for both.

Welcome to the Forum and congrats on scoring your U300SE.  A bit of terminology clarification will help the discussion.

A "converter" receives AC power and converts it to DC power that is used to charge a battery, or to directly power DC devices.

A "inverter" receives DC power from a battery and inverts it to AC power.

A "inverter/charger" performs dual functions.  It can take DC and convert it to AC.  It can take AC and output DC to either charge a battery, or (in some cases) to directly power a DC device.

SO, the question is, what do you have on your coach?

If the Heart device is a inverter/charger, then it NOT likely that you also have a converter.

OTOH, if the Heart device is only a inverter, then you probably DO also have a converter.

Can you take a photo of the Heart device and post it.  Would help with long range troubleshooting.

The spec sheet linked below, from our ForeForum WiKi, lists the standard equipment for 1995 U300.  However, older coaches are often modified/updated from factory original specs.

https://wiki.foreforums.com/_media/through_the_years:specs:1995-u300-specifications.pdf

Our exceptional ForeForum Library has an extensive collection of electrical schematics.  One of the two linked below should cover the 110V relay system in your coach (most likely the second one).  Your 1995 U300, although still a Unihome design, was built during a transition year, and shares many of the same system components with the later Unicoach models.

https://www.foreforums.com/index.php?media/item/a-2700-07-110v-elect-relay-system-u280-u300.3267/

https://www.foreforums.com/index.php?media/item/a-2700-07-1995-u295-110v-elect-relay-system-wiring.5207/

If its the original Heart Freedom 25, then this should be the manual: This is the version after Heart was sold to Xantrex, since you mention your interior panel says Xantrex.

Just to say it out loud, if that is the original, its 30 years old you really should begin to consider upgrading it as its on borrowed time (IMO) ... its also a modified sine wave output which is not "great" these days.

The remote panel for the inverter should have a switch to turn on charge, to charge the batteries. If that is turned on and still not charging it is probably no good.

Thanks all. Links to photos below.
The inverter/charger is a Heart Interface Freedom 25.
When the coach is plugged into an extension cord at the house (20 amp), the Xantrex panel initially shows the following:
AC In - Battery State Full - DC Volts 10.0 (Red light) - DC Amps <10 (Green Light) - Incoming AC Breaker Amps set to 20.
 
If I turn the power switch off on the inverter for about 10 sec. and turn it back on, it starts humming like its working (having some off-grid living experience I am familiar with the buzz).  While it's buzzing, the control panel shows DC Volts 13.0-DC Amps 25 and everything that is 12v powered in the coach works great. 

Go out an hour later and it's back to the first scenario and I reset the Inverter again.

https://www.dropbox.com/scl/fi/okax00xj4vc2hdyeif5il/IMG_7897.HEIC?rlkey=ord71ae7qlgcxtlgrjsahj4kk&st=nimc1hmi&dl=0
https://www.dropbox.com/scl/fi/8j1rbts8bw8umio5ofwmy/IMG_7898.HEIC?rlkey=75fddk9chi17s1rb00bd6nvuq&st=7pyj685t&dl=0
https://www.dropbox.com/scl/fi/ln9b8sihqwhsaf7glgg1c/IMG_7900.HEIC?rlkey=ha0ngb0h7l0o0yloyrk7l3d69&st=tx2usvee&dl=0
https://www.dropbox.com/scl/fi/3ajci5u8v5rztd4xd6foy/IMG_7901.HEIC?rlkey=5rzdfkg9ugtj1vuj41ogrbiwp&st=a5vceo2m&dl=0
https://www.dropbox.com/scl/fi/25t6l49oyhvoliqb6bwyo/IMG_7902.HEIC?rlkey=d8pdywcg5yi5bockqaykmhddt&st=kufklj6o&dl=0
https://www.dropbox.com/scl/fi/rc2ysj2wwaia79cnl92dq/IMG_7903.HEIC?rlkey=y4mthmk8bfc5c7bif2ycvekpv&st=4yrfzy39&dl=0

steve: edited/Attached images for quick viewing

The batteries indicating 10 volts and the charger topping off and shutting down quickly indicates the bank is probably bad. I would begin with having the batteries tested outside the rig. Charge and load test. It is possibly time also to upgrade the inverter/charger.

You can try the whats in the manual Which basically is trying to trickle charge the batteries back to a nominal level.  It sounds like the unit is simply turning itself off as a protection.  Chances are the batteries are not recoverable but maybe the slow bring-up may give you some time.

Turn the power share down to 5 if it will go that low.

Agree.  That 5 amp setting of 120 VAC will charge the batteries at over 40 amps @ 14 VAC. Plenty!