Inverter Question

[Denile]

We are new to BB and are loving our bus. We have been going through the systems and are so impressed with how much stuff is actually working on a 30+ year old bus. My question is this: I do not believe my inverter is working. I have the original PACS 1500. The switch seems to work and I have power to the right wires between the remote switch and inverter. My reset light and low battery light keeps coming on even though there is no load and it has 13.x volts in from the batteries. I am looking at a newer unit, but the new unit has 2 ac wires and mine has just one. I only have one breaker box but it has different color breakers (assume color coded for a reason) is there a resource on how to wire a 2 ac wire inverter/charger with built in transfer switch to my one wire system. A second questions should I have ac power to that one wire at my current inverter when I am on shore power?

[JMorton]

We could help with the newer inverter if you could tell us what make and model it is.


Having said that, converting from the original inverter setup can be done. In my bus ( 1988 PT-40) there was a relay under the sink in an enclosed box which would switch some outlets from shore power to the inverter when the inverter was on. This required no special breaker wiring. A previous owner changed it from that system when they put in a newer inverter/charger. The newer inverter has two AC connections, input and output. The input is fed from a breaker in the panel. The AC output goes to a new small breaker box which they added on to the back of the existing breaker panel. They moved the romex wires from the original breaker panel for the circuits that they wanted on the inverter to the new breaker box. This, of course, was hidden and un-documented. I did a bit of wire tracing and documenting in order to understand what they did. I had room to add another breaker to the inverter breaker panel and moved the circuit for the dinette area outlet to the inverter also.

The relay under the sink was getting noisy with a buzzing hum. Since the new inverter includes a transfer switch, I removed the buzzing relay and connected the wires that went to the relay output to the wires that went to the relay inverter input. The new inverter has a built-in transfer switch so the old relay was no longer needed.


As for your inverter cutting out, try cleaning or possibly replacing the cables from your battery bank to the inverter. Corrosion and bad connections can drop voltage to the point where the inverter will drop out. These problems will mostly appear under load. With only a small demand on the inverter the voltage will stay up enough to keep the inverter on.

[Denile]

I am looking at a Xantrex Freedom model. Just not sure what size yet.

All of this makes sense. Is there anyway possible to connect to the current inverter circuits rather than rewiring and adding sub panels?

My terminals are completely clean at the inverter i just need to trace them to the other end and find them there. I am getting over 13 volts at the inverter so I am not sure why it would be showing low batteries. I wouldnt think it would drop until it got below 11 or 12. Also as far as the huming that answers my next investigation of what that annoying humming is
under my sink. lol.

[JMorton]

Originally Posted by Denile

I am looking at a Xantrex Freedom model. Just not sure what size yet.

All of this makes sense. Is there anyway possible to connect to the current inverter circuits rather than rewiring and adding sub panels?

Yes, you should be able to connect the AC wire to the inverter's output and it will supply AC to that circuit ( which feeds a transfer switch most likely) If the inverter is also a charger, it will have an AC input which will need to be fed from the circuit breaker feeding your current battery chargers, assuming that you want to replace them with the new inverter/charger.

Originally Posted by Denile

My terminals are completely clean at the inverter i just need to trace them to the other end and find them there. I am getting over 13 volts at the inverter so I am not sure why it would be showing low batteries. I wouldnt think it would drop until it got below 11 or 12. Also as far as the huming that answers my next investigation of what that annoying humming is
under my sink. lol.

Measure the voltage at the inverter terminals while the inverter is on and under a light load and perhaps again while under a heavier load. If the voltage is solid at the terminals it is most likely an inverter problem. The bad connections are usually found on the battery cables / terminals.

[bobbiemartin]

Originally Posted by Denile

I have the original PACS 1500. The switch seems to work and I have power to the right wires between the remote switch and inverter. My reset light and low battery light keeps coming on even though there is no load and it has 13.x volts in from the batteries. I am looking at a newer unit, but the new unit has 2 ac wires and mine has just one.

The inverter manufacturer should have schematics on how to wire the inverter. When you say 2 AC wires, what exactly are you referring to? Probably they are AC power in and power out? Is this a power assist inverter? If so, and you want to use that feature, it will require a fair amount of reworking the existing wiring in the coach. However, again depending on the specific unit, you could probably use only AC power out and wire the same as your current inverter. As mentioned, adding an inverter charger will require removing the current battery chargers and related wiring.

On the built in inverter transfer switch, I’m assuming this is a power assist inverter. Keep in mind a power assist inverter/charger built in transfer switch is not the same as a shore/generator transfer switch. The shore/gen transfer switch will select the AC input. The internal inverter transfer switch will switch between the inverter and AC input power (from the shore/gen transfer switch). Now, understand there are inverters that do both, that is they have two AC inputs (typically shore and generator for our use) and one AC output. There are also some inverters that have two AC outputs (and some with two AC inputs and two AC outputs for that matter), one output that gets inverter power assist and one that is a pass through.

I recommend you thoroughly understand what you want to do before you buy a unit. There is all kinds of equipment available to do most anything you want. The inverter is but one piece of the power supply for your coach. Do you have plans for solar or different battery chemistries? Some planning now will allow adding other equipment later much easier. If you want to read up on the various types of inverters and related equipment, I suggest you go here. There are lots of free downloads but maybe start with “The Energy Unlimited Book” and “The Wiring Unlimited Book”. Now these are from Victron so obviously promotes their products but much of the information is basic so will be adaptable to whatever equipment you choose. Also keep in mind it’s written more for European systems than US but still is useful. As always, my go to question is “What are you trying to achieve?” Once you have a basic understanding of what is available and what you want, picking the right components becomes much simpler.

On the buzzing, it’s likely a relay. Just to make it fun, Bluebird hid relays all over the bus, typically in the most inaccessible locations possible.

[Denile]

JMorton. Thanks for the information. This is what I hoped for. I do plan on replacing my battery charger, it is aftermarket and I believe it is single stage and seems to be overcharging at times. The inverter/charger I am looking at is a multistage charger.

Bobbie Martin I am hoping when I do not have power via generator or shore power, my inverter is active. I would assume if I use the 110 out from my current inverter as my out on the new inverter, I would just need a 110 in from somewhere so the inverter knows rather or not there is 110 coming from somewhere else. As far as down the road solar is possible but not currently planned. Right now I just want a working inverter and replace my current battery charger.