Simple electrical question

Topic: Simple electrical question (Read 891 times) previous topic - next topic

Simple electrical question

September 20, 2023, 07:14:55 pm

This one should be simple for all you Foretravel gurus. Help me to understand how the electrical system works. When I'm plugged in, all the outlets seem to feed directly from the external cord. I always assumed that they fed from the inverter and the inverter just recharged the batteries. Apparently that's not how it works. So I assume the ATS's have something to do with it? There are two ATS's, so is one bypassing the inverter completely when I am plugged in?

Also, another quick question. My water heater has two switches, one under the bed and one under the kitchen sink. Both of those switches have to be on to heat water with electricity. Why are there two switches?

Thanks
Kevin

Re: Simple electrical question

Reply #1 – September 20, 2023, 11:03:36 pm

The switch under the bed is for the block heater and the one by the sink is for the hot water
heater. When plugged in the transfer switch puts all the plugs on shore line and the inverter
charges the house batteries.

Re: Simple electrical question

Reply #2 – September 21, 2023, 12:23:00 am

It sounds as if you may be running the inverter all the time, even when on shore power. If it is like ours, you can disable the inverter while still having the charger section of the inverter/charger enabled. If that is the case, I would disable the inverter section while on shore power. Running it draws a small amount of power, even in standby, and will likely reduce the useful life of the inverter. We only enable the inverter when we are not hooked to shore power, and even then only when we need 110v power.

Re: Simple electrical question

Reply #3 – September 21, 2023, 11:34:03 am

If you are plugged into shore power the AC current is passed through the inverter, no need to have the inverter on. Leave the charger on it will keep your batteries charged for the lights a such. We only turn the inverter on (when not plugged in) when needed. Even when not doing anything the inverter still draws power on stand by.

Re: Simple electrical question

Reply #4 – September 21, 2023, 11:44:11 am

OK, with TWO ATS's:

First one selects between shore power and generator.

Second one selects between the First and the inverter.

If only a single ATS:
Same as "First" above.

The inverter/charger has an internal ATS-- when it sees 120 VAC from either shore power or generator, it merely "passes it through" to all circuits downstream of the inverter/charger. When no external source of 120 VAC AND the inverter is turned on, the inverter "inverts from your house battery bank" to provide 120 VAC to those same circuits downstream of the inverter/charger.

Re: Simple electrical question

Reply #5 – September 21, 2023, 11:49:42 am

Quote from: kjsifer – September 20, 2023, 07:14:55 pm

Also, another quick question. My water heater has two switches, one under the bed and one under the kitchen sink. Both of those switches have to be on to heat water with electricity. Why are there two switches?

Thanks
Kevin

In my old 1997 there was a switch under the bed to turn on power for the electric part of the water heater as a disconnect. The switch by sink you could turn water heater on and off, but if the switch by the bed was off, the water heater had no power for the electric element.

Re: Simple electrical question

Reply #6 – September 21, 2023, 11:58:06 am

On our U280, the water heater switch at the foot of the bed is for the 120v heating element in the WH, if it's on you have 120v to the heater, the switch at the sink is for the 12v control of the propane igniter board and does not have to be "on" for the 120v element to work. They are independent of each other, not sure why the OP states that they both have to be on for the heater to work.
That's news to me.

Re: Simple electrical question

Reply #7 – September 21, 2023, 12:55:53 pm

Quote from: oldguy – September 20, 2023, 11:03:36 pm

The switch under the bed is for the block heater and the one by the sink is for the hot water
heater. When plugged in the transfer switch puts all the plugs on shore line and the inverter
charges the house batteries.

Not in my rig. I have a block heater AND a water heater switch under the bed.

Kevin

Re: Simple electrical question

Reply #8 – September 21, 2023, 12:57:55 pm

Quote from: turbojack – September 21, 2023, 11:49:42 am

In my old 1997 there was a switch under the bed to turn on power for the electric part of the water heater as a disconnect. The switch by sink you could turn water heater on and off, but if the switch by the bed was off, the water heater had no power for the electric element.

That must be what it is, sort of a circuit breaker. Because they both have to be on for the water heater to work on electric.

Thanks
Kevin

Re: Simple electrical question

Reply #9 – September 21, 2023, 01:01:20 pm

Quote from: FourTravelers – September 21, 2023, 11:58:06 am

On our U280, the water heater switch at the foot of the bed is for the 120v heating element in the WH, if it's on you have 120v to the heater, the switch at the sink is for the 12v control of the propane igniter board and does not have to be "on" for the 120v element to work. They are independent of each other, not sure why the OP states that they both have to be on for the heater to work.
That's news to me.

Ours is different. We have two switches under the sink, one for propane and one for electric. You only have to turn on the propane switch to fire up the water heater on gas. For the electric part of the heater to work, you have to turn on the switch under the sink AND the switch under the bed. Strange system, just wondering why they set it up that way. The only reason I can think is that the small switch under the sink acts as a relay and the main, larger switch under the bed is where the power is flowing through.

Kevin

Re: Simple electrical question

Reply #10 – September 21, 2023, 01:02:55 pm

Quote from: wolfe10 – September 21, 2023, 11:44:11 am

OK, with TWO ATS's:

First one selects between shore power and generator.

Second one selects between the First and the inverter.

If only a single ATS:
Same as "First" above.

The inverter/charger has an internal ATS-- when it sees 120 VAC from either shore power or generator, it merely "passes it through" to all circuits downstream of the inverter/charger. When no external source of 120 VAC AND the inverter is turned on, the inverter "inverts from your house battery bank" to provide 120 VAC to those same circuits downstream of the inverter/charger.

Thanks Brett,
That's what I was looking for!

Kevin

Re: Simple electrical question

Reply #11 – September 21, 2023, 01:10:54 pm

Quote from: dbennett9 – September 21, 2023, 12:23:00 am

It sounds as if you may be running the inverter all the time, even when on shore power. If it is like ours, you can disable the inverter while still having the charger section of the inverter/charger enabled. If that is the case, I would disable the inverter section while on shore power. Running it draws a small amount of power, even in standby, and will likely reduce the useful life of the inverter. We only enable the inverter when we are not hooked to shore power, and even then only when we need 110v power.

I get your reasoning, here's mine.

If my inverter is off, once I disconnect from shore power, then I have UPS's inside of the coach start beeping, clocks need to be reset, etc. Seems to me just easier to leave it running. It doesn't take much power and it's made to run for years. I replaced the original with a Victron. Typically, on and off surges are harder on electronics than a steady state supply of power.

Kevin

Re: Simple electrical question

Reply #12 – September 21, 2023, 01:22:43 pm

Some coaches have an under-bed switch to control water heater's 120-volt electric heating element. This switch is separate from block heater switch.

The under sink 12-volt switch powers the water heater circuit board that manages the propane flame. If shore power is limited, it may be better to keep the under-bed switch off and heat water with only propane.

A previous owner may have replaced water heater with a model where the water heater circuit board manages both electric heating element and propane heat. In this case the under-bed can be left on.

Re: Simple electrical question

Reply #13 – September 21, 2023, 02:03:13 pm

You're lucky if there's two switches for the ele water. I've burned my electric element out twice by forgetting to turn off the switch HIDDING under the dang bed.
Don't drain or run out of water with that switch on. At least with it buy the sink it's obvious that the ele water is on.

Ours has 3 switches under sink. One for propane, one for water pump and another for instant hot dispenser. Now disabled and removed. ,, I tried to reconfigure the the dispenser switch for 110 control of a transfer type switch but failed.

I've now moved on to adding a 110v 3gal instant hot into the loop. Co. Says it can be added as a supplement to existing water heater.

Re: Simple electrical question

Reply #14 – September 22, 2023, 08:43:51 am

A few circuit drawings that may help

HTH

Re: Simple electrical question

Reply #15 – September 23, 2023, 10:27:56 pm

Kevin
Below the water heater there should be a valve that can be opened which heats the water heater from the engine using the feed for the dash heater while you are traveling, giving you hot water when you arrive at your destination. So there is the engine which we use all the time, the electric and the propane to heat the water.

Re: Simple electrical question

Reply #16 – September 27, 2023, 06:40:00 pm

Our inverter/chargers (like Magnum, etc) operate in two states: Charging OR Inverting. When one is ON, the other is OFF. So leaving the inverter and charging switches on all the time will not stress the inverter. Some have 120-volt devices like computers, DVR, etc. operating all the time, and the best inverter/chargers will seamlessly transfer 120-volt supply from/to generator-shore power, and inverter without affecting DVR operation.

But to safeguard house battery, no high-amp appliances should be plugged into electric outlets that are powered by inverter. We identified outlets that are NOT on inverter and only used them for heaters, hair dryers, etc. If heaters are plugged into inverter outlets, and campground loses power during the night, the heater could drain the battery if inverter switch is on.

Very worthwhile to identify electric outlets as inverter/shore/gen or shore/gen only. Even running high amp devices like heaters on inverter outlets with inverter switch off, could still stress inverter/charger internal transfer relay on coaches with only one transfer switch.

Re: Simple electrical question

Reply #17 – October 07, 2023, 06:58:25 pm

So,
I've been kicking this idea around for a couple weeks before posting it. We are currently hooked up to a 15 amp circuit and it's getting a little chilly out. We can't run more than one electric heater at a time or a microwave and a heater, etc. It seems like this electrical design from 20 years could use some updating.

I have a modern Victron inverter that has a the Power Assist feature. In other words, it will pull power from the batteries when there's not enough power coming across the A/C line. But, it seems to me that it is not useful because of the way that this coach is wired up. With the ATS selecting the shore power first, I can't really even take advantage of this feature. I'm thinking it may be in my best interest to get rid of the second ATS or put a manually selectable one in or something in order to use the full capability of my inverter. Thoughts?

Thanks,
Kevin

Quote from: wolfe10 – September 21, 2023, 11:44:11 am

OK, with TWO ATS's:

First one selects between shore power and generator.

Second one selects between the First and the inverter.

If only a single ATS:
Same as "First" above.

The inverter/charger has an internal ATS-- when it sees 120 VAC from either shore power or generator, it merely "passes it through" to all circuits downstream of the inverter/charger. When no external source of 120 VAC AND the inverter is turned on, the inverter "inverts from your house battery bank" to provide 120 VAC to those same circuits downstream of the inverter/charger.

Re: Simple electrical question

Reply #18 – October 07, 2023, 07:12:23 pm

Quote from: kjsifer – October 07, 2023, 06:58:25 pm

With the ATS selecting the shore power first, I can't really even take advantage of this feature.

Your ATS can be configured so the generator is primary if you want.

Mike

Re: Simple electrical question

Reply #19 – October 08, 2023, 01:42:42 pm

Quote from: Pamela & Mike – October 07, 2023, 07:12:23 pm

Your ATS can be configured so the generator is primary if you want.

Mike

The goal is to not burn diesel fuel. I have a 15 amp shore power connection. Just very limited in the amount of power I can pull across it. The batteries and inverter could act as a buffer but the way the ATS's are wired, the inverter and batteries are a paperweight as long as you have any kind of shore power.

Kevin

Re: Simple electrical question

Reply #20 – October 08, 2023, 07:30:01 pm

Quote from: kjsifer – October 07, 2023, 06:58:25 pm

So,
I've been kicking this idea around for a couple weeks before posting it. We are currently hooked up to a 15 amp circuit and it's getting a little chilly out. We can't run more than one electric heater at a time or a microwave and a heater, etc. It seems like this electrical design from 20 years could use some updating.

I have a modern Victron inverter that has a the Power Assist feature. In other words, it will pull power from the batteries when there's not enough power coming across the A/C line. But, it seems to me that it is not useful because of the way that this coach is wired up. With the ATS selecting the shore power first, I can't really even take advantage of this feature. I'm thinking it may be in my best interest to get rid of the second ATS or put a manually selectable one in or something in order to use the full capability of my inverter. Thoughts?

Thanks,
Kevin

Kevin I have a victron inverter charger as well as 600 amps of victron lithium batteries. I also have the victron multi control which allows me to control the inverter to on/off for charger only. It also allows me to set a current limit. So if I'm plugged into 30 amps I could set it for 30 and it won't pull more than that. Usually though whatever I'm plugged into I set it for less so right now I'm in a 50 amp circuit but my current limit is set to 40. If I should try to pull more than 40 amps to say start the air conditioner or microwave and induction cooking at the same time etc the power assist feature will come on. On the multi-control a red light will also come on that says overload. Right now I'm plugged into shore power but it works just as well when boondocking and using mostly solar. You just have to have the right batteries for that feature. I would not do it with lead acid batteries including AGM or gel. Lithiums can take the high flow of current a lot better. I think it would be a good way to kill batteries early if it was used a lot but if you had the right kind of batteries and the right amount it works great.
Headed to include the fact that I also do not have automatic transfer switches at all but a 50 amp threway Blue sea systems selector switch. So you have to manually switch between generator or shore power. It takes up no room in there except for the wiring which left space for me to hardwire the power watch dog and a Hughes autoformer.

Re: Simple electrical question

Reply #21 – October 08, 2023, 10:17:56 pm

Quote from: Journey, Roam, Explore – October 08, 2023, 07:30:01 pm

Kevin I have a victron inverter charger as well as 600 amps of victron lithium batteries. I also have the victron multi control which allows me to control the inverter to on/off for charger only. It also allows me to set a current limit. So if I'm plugged into 30 amps I could set it for 30 and it won't pull more than that. Usually though whatever I'm plugged into I set it for less so right now I'm in a 50 amp circuit but my current limit is set to 40. If I should try to pull more than 40 amps to say start the air conditioner or microwave and induction cooking at the same time etc the power assist feature will come on. On the multi-control a red light will also come on that says overload. Right now I'm plugged into shore power but it works just as well when boondocking and using mostly solar. You just have to have the right batteries for that feature. I would not do it with lead acid batteries including AGM or gel. Lithiums can take the high flow of current a lot better. I think it would be a good way to kill batteries early if it was used a lot but if you had the right kind of batteries and the right amount it works great.
Headed to include the fact that I also do not have automatic transfer switches at all but a 50 amp threway Blue sea systems selector switch. So you have to manually switch between generator or shore power. It takes up no room in there except for the wiring which left space for me to hardwire the power watch dog and a Hughes autoformer.

Thanks for weighing in! I think that is the key, get rid of the ATS's or wire them differently. The way I am wired now, if I'm on shore power I can shut my inverter off and everything still runs just fine as if it doesn't exist. It's not really doing anything except charging the batteries unless I disconnect the shore power.

I also have my input rate set, but I don't think it really matters since the ATS defaults to strictly shore power, so we can turn everything on in the coach and will trip the breaker of the 15 amp outlet I'm plugged into. Going to have to do some rewiring and get the coach up to a more modern configuration to take advantage of the Victron technology.

Kevin

Re: Simple electrical question

Reply #22 – October 09, 2023, 04:46:46 am

I have the one ATS that switches shore power and generator, there was another one that was manual for the original inverter. It's not currently in use. I have a Victron Muliplus-II and it will transfer between shore power and battery power as needed. Not sure which inverter you have, but if it's like mine it will do exactly what you want it to. You can set a current limit on the AC in and it will charge the batteries or supplement the AC loads as needed. Take some pictures of your wiring and setup since it doesn't sound original. There are a bunch of people on this forum that can help with wiring suggestions.

Re: Simple electrical question

Reply #23 – October 09, 2023, 09:35:35 pm

Quote from: kgrover – October 09, 2023, 04:46:46 am

I have the one ATS that switches shore power and generator, there was another one that was manual for the original inverter. It's not currently in use. I have a Victron Muliplus-II and it will transfer between shore power and battery power as needed. Not sure which inverter you have, but if it's like mine it will do exactly what you want it to. You can set a current limit on the AC in and it will charge the batteries or supplement the AC loads as needed. Take some pictures of your wiring and setup since it doesn't sound original. There are a bunch of people on this forum that can help with wiring suggestions.

I have the two ATS design. It is original to the coach.

Kevin

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