RT 190 Battery and Inverter

[Jon in AZ]

Originally Posted by JohnnyFry

The inverter is a device which converts 12VDC to 120VAC. It is not the same as the isolator, which seperates the house and chassis batteries but allows them both to be charged from the engine alternator. The inverter normally includes a charger to charge the house battery when connected to shore power. Units without an inverter normally have a “converter” which charges the batteries and provides 12VDC when on shore power but has no provision to make 120VAC.

Right. The inverter question was separate from the battery question. And yes, I meant inverter.

The battery question was about what battery types I can use to replace the dead OEM coach batteries. Still not clear on whether there is adequate venting in the battery compartment for flooded batteries.

The inverter question was about a couple of posts I read that mentioned a factory safety defect in the inverter installation in some newer RT’s. I wanted to know if it’s something I need to have checked out.

The isolator came up because I also mentioned a discharged chassis battery (a third issue that presented after I started this thread). Battery and charging system tested good, but something is causing the chassis battery to discharge when parked more than a couple of weeks to the point the engine won’t start. A faulty isolator could be a cause I hadn’t considered. There are also at least two bad chassis circuits- the dome light (wouldn’t shut off so I removed bulb), and the high mount brake light (housing melted, doesn’t work) that could be the culprit.

I guess maybe the real question is where to start. My current plan: (1) troubleshoot chassis wiring issues, (2) new coach batteries, (3) check inverter (if needed).

Yes? No?

[rowiebowie]

Originally Posted by Jon in AZ

My current plan: (1) troubleshoot chassis wiring issues, (2) new coach batteries, (3) check inverter (if needed). Yes? No?

I would suspect the batteries, coach and engine, are toast, so in spite of costs I'd go 2) full battery replacements, 3) check inverter, and then 1) troubleshoot chassis wiring issues.

My reasoning is in the old days your battery ran down (usually with some slow crank warning) and things went dead. A fresh battery fixed it right up.

Now with all the electronics in the chassis, a battery fail is sometimes immediate with no warning. And I've seen some strange reaction by the electronics where some things work, some don't, and some act strangely. The thing that stays the same, however, it is always the batteries.

Good luck.
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[Jon in AZ]

Originally Posted by rowiebowie

I would suspect the batteries, coach and engine, are toast, so in spite of costs I'd go 2) full battery replacements, 3) check inverter, and then 1) troubleshoot chassis wiring issues.

My reasoning is in the old days your battery ran down (usually with some slow crank warning) and things went dead. A fresh battery fixed it right up.

Now with all the electronics in the chassis, a battery fail is sometimes immediate with no warning. And I've seen some strange reaction by the electronics where some things work, some don't, and some act strangely. The thing that stays the same, however, it is always the batteries.

Good luck.
.

I went to replace the chassis battery, and it tested good, very good, actually. The shop saw no reason to replace it.

Coach batteries are definitely toast. Will replacing them prevent discharge of the chassis battery? Why? I thought I had everything in the coach turned off, and even if not, shouldn’t the isolator prevent the coach from discharging the chassis?

[rowiebowie]

Originally Posted by Jon in AZ

I went to replace the chassis battery, and it tested good, very good, actually. The shop saw no reason to replace it.

Coach batteries are definitely toast. Will replacing them prevent discharge of the chassis battery? Why? I thought I had everything in the coach turned off, and even if not, shouldn’t the isolator prevent the coach from discharging the chassis?

In a perfect world the isolator should do only good (connect the batteries when charging - good) and separate them so one does not discharge the other. It is designed for a functioning battery system. But if the batteries are bad, who knows what it is reading and doing.

As to the chassis battery, it may have tested ok and maybe it is ok. But unless the shop kept the battery under a load test for an hour or so, it may not be. Like I said, it's not so cut and dried anymore with today's batteries and electronics.

I've replaced coach batteries and many engine batteries in dozens of automobiles in the past 45 years. In my anecdotal experience, a new battery has always fixed my problem. In that time, there was never an external reason for the battery failures. Never a bad charger, alternator, wiring short, or any other electronic component failure related to the draining of the battery.
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[JohnnyFry]

AGMs are the most popular replacements for coach batteries, their only downside is cost: they are roughly 2X times of flooded batteries. Before replacement I would check your Isolator as it sounds as if it could have a problem. Be aware that there are also 2 self resetting circuit breakers between the isolator and the coach batteries in the rear. They occasionally go bad and reduce charging rate to the coach battery to almost nil. They are cheap ($5) to replace. Testing the isolator with a multimeter is fairly simple: With the engine running check the voltage on all 3 terminals: it should be about 14 volts. The middle terminal which goes to the alternator should read about 0.7 volts higher than the outer terminals. If that is the case the alternator is charging and the isolator is OK. There is also the possibility that one of the diodes has failed by shorting. To check that you need to remove all 3 wires from the terminals (DISCONNECT ALL BATTERIES FIRST!) and check in both directions with the probes (switch red and black) between the center terminal and each outer terminal. One direction should read a low ohm value and the other should read open. BTW: Where are you in Az (I am in Tucson)