How to disconnect charging circuit?

Mbtuner · 08-19-2022, 10:57 AM

2022 Micro Mini 2225RL. I want to be able to plug my shore power into my 1500 amp inverter. I need to take battery charging out of the loop when I'm doing that.

Has anyone figured that out?

Thanks in advance,

George

Morich · 08-19-2022, 03:46 PM

I'm guessing there is a bit of difference in terms at play here!
Inverters use battery to turn (invert) 12 VDC to make AC. So connecting an inverter to AC is not likely what you want to do.
Are you dealing with an inverter/ charger which charges your batteries and you want to stop that operation?
Maybe we need more info on the what and why of your question and more info on which item you have?
I normally thing of a set of wires from the charging which moves power to the battery when plugged and then movespower from the batteries to the inverter when it is used to make AC. That makes it harder to break the connection for one but not the other.

powercat_ras · 08-19-2022, 03:49 PM

In you electrical box with AC circuit breakers look to see if there is a dedicated 15 amp breaker for the converter-charger, that's what charges the battery.

wyocamper · 08-19-2022, 09:55 PM

On a 5th wheel I used to have I put one of these on the battery negative terminal, then connected the inverter and ran a line from that to the shore power input. That allowed me to energize the 110 outlets without the converter trying to charge the batteries at the same time. Worked for me and what I wanted, like watching TV and charging phones.

jerichorick · 08-20-2022, 05:09 AM

Quote:

Originally Posted by Mbtuner

2022 Micro Mini 2225RL. I want to be able to plug my shore power into my 1500 amp inverter. I need to take battery charging out of the loop when I'm doing that.

Has anyone figured that out?

Thanks in advance,

George

George, what is the need for this? Why do you feel the batteries need to be disconnected? As far as I know the inverter needs the 12V present in order to operate.
Do you understand how a inverter functions? Many people don't.
Here is how my Magnum works:
When on shore power (inverter and charger turned on at the remote panel) ; the internal ATS passes the shore power through to the RV service panel. At the same time the inverter determines if the batteries need charging.
When shore power is not present: the inverter internal ATS drops off and connects the inverted power produced by the battery bank and the function of the inverter to the RV service panel.
That is the very short version of what an inverter does.
So I'm back to my original question. Why do you feel you need the batteries disconnected?
Rick

Mbtuner · 08-20-2022, 11:47 AM

What I'm trying to do is power my trailer's 120v circuits from my separate battery, solar and inverter. I have a portable solar setup charging an extra AGM battery. That is wired to a 1500 watt inverter. That inverter has three plug ins for 120 volt appliances. I don't want to just run an extension cord to my auxiliary inverter, but I can.

I want to take my 30 amp shore power cord and, with an adapter, plug into the inverter. But, I want to switch off the built in charger on the house setup as it would only cause un unneeded draw, a loop if you will.

We rarely need 120 volts but somtimes we'll warm something up in the microwave or run a fan or a laptop charger. . I'm not trying to run multiple things at once.

BobC · 08-20-2022, 12:44 PM

The problem with your plan is that your lights and several other devices run off your house batteries' 12V DC power so you need to keep the house batteries charged and online. Once your batteries are charged, the converter should consume minimal 120V power. Alternatively you can locate the 120V breaker that supplies the converter/charger and turn it off when you don't want it to run.

I'd suggest that you get a multimeter with a clamp-on amp probe that reads both AC and DC amps. They're not hugely expensive. That way you can measure the draw on your "extra battery" to see exactly how much power the converter consumes. Once you have one you'll find a million uses for it. The nice thing about a clamp-on meter is that you don't have to disconnect any wires to use it. This is what I have:

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

Less expensive ones are available but be careful to confirm that the clamp works on both AC and DC and some descriptions are misleading.

Just remember, 1500W is only 12.5A. I'd suggest leaving all your 120V breakers off except the one powering the outlet you're using to avoid a problem.

Mbtuner · 08-20-2022, 04:11 PM

"The problem with your plan is that your lights and several other devices run off your house batteries' 12V DC power so you need to keep the house batteries charged and online"

Help me think this through. I plug shore power into a 120 volt source, now the house runs on that, leaving the house battery out of the loop, right? That 120 volt source just happens to be my inverter.

So my propane fridge is about the only consumer unless I switch something else on.

We used to get 5 days boondocking before needing to recharge the house battery. We use a Mr Buddy heater instead of the furnace, no TV use.

I use a home made 200 watt portable solar suitcase for the aux battery and my MM has 190 watts on the roof for the house battery

I just need take charging of the house battery from the house converter out of the loop with a simple switch. If I pull a fuse for the converter I lose my 120 volt circuits.

BobC · 08-20-2022, 05:24 PM

Quote:

Originally Posted by Mbtuner

"The problem with your plan is that your lights and several other devices run off your house batteries' 12V DC power so you need to keep the house batteries charged and online"

Help me think this through. I plug shore power into a 120 volt source, now the house runs on that, leaving the house battery out of the loop, right? That 120 volt source just happens to be my inverter.

So my propane fridge is about the only consumer unless I switch something else on.

We used to get 5 days boondocking before needing to recharge the house battery. We use a Mr Buddy heater instead of the furnace, no TV use.

I use a home made 200 watt portable solar suitcase for the aux battery and my MM has 190 watts on the roof for the house battery

I just need take charging of the house battery from the house converter out of the loop with a simple switch. If I pull a fuse for the converter I lose my 120 volt circuits.

You didn't mention that you had roof-mounted solar. Given that, I don't think you're going to have a problem. I don't think your house batteries will ever get low enough to put much of a drain on your "extra" AGM.

In terms of your original plan, from your description, it appears that your converter and power center are a single, integrated unit, similar to what I have installed in my van. Integrated units like this aren't universally the case, especially for those of us with motorhomes, hence my previous, unworkable suggestion. You'll have locate the make and model number of your power center/converter. Once you have this, let us know and we may or may not be able to help. However, I'm not hopeful, based on the following:

The one in my van is made by Powermax WFCO and looks like this:

https://smile.amazon.com/PowerMax-PP...e%2C268&sr=1-2

If your unit is similar, I think you're out of luck unless you're an electronics expert. There's only one set of cables to the battery and disconnecting them would disconnect all the 12V circuits including the refrigerator. I looked at the installation manual for my van's power center and I don't see any way of disabling the charging function while leaving everything else, including the 12V feed from your house batteries, intact.

There's only one set of cables from the battery. Disconnecting the house battery from it would disconnect it from all the DC circuits, including the refrigerator, lights, etc., which would be problematical. Disconnecting your battery cables at the house battery or installing a battery disconnect switch would result in the same issue.

Fred 2106DS · 08-20-2022, 07:19 PM

Quote:

Originally Posted by Mbtuner

Help me think this through. I plug shore power into a 120 volt source, now the house runs on that, leaving the house battery out of the loop, right? That 120 volt source just happens to be my inverter.

Hi George, If I understand what you are trying to accomplish, all you need to do is what "powercat_ras" recommended, turn off the AC circuit breaker that your converter charger is connected to. The only issue you may have is that more than one AC circuit maybe connected to that circuit breaker.

In my Micro Minnie, the converter charger was connected to a 15 amp. circuit breaker labeled "GENERAL" along with the one other AC circuit. Since there was more than one AC circuit connected to that circuit breaker I disconnected my converter charger from that circuit breaker when I switched to lithium batteries. If the converter charger would have been on a dedicated circuit breaker I would have just turned the circuit breaker off.

If you find your converter charger is connected to a circuit breaker with more than one circuit, if you have an open space to add another circuit breaker, you could add an additional circuit breaker and use that as a dedicated on/off switch.

Here is a picture of my Power Center. The converter charger was connected to the center 15 amp. circuit breaker. As you can see, I have the space to add additional AC circuit breakers if I want to.

Mbtuner · 08-24-2022, 06:33 PM

Thanks to everyone for your help. It looks like what I want to do gets comlicated unless Fred 2106DS is right. I'll look at that first. If that doesn't work out I think I'll leave the charging system powered and see how much it hurts. We don't need it tat often anyway and I can shut it off when not needed.

**creativepart** · 08-25-2022, 09:16 AM

Quote:

Originally Posted by Mbtuner

We rarely need 120 volts but somtimes we'll warm something up in the microwave or run a fan or a laptop charger. . I'm not trying to run multiple things at once.

Think again. A 1500w inverter will likely not run your Microwave. And keep in mind that a 1500w inverter is more akin to a 15-amp home power receptacle - except that converting 12v to 110v isn't 100% efficient and so it's more like a 12-amp receptacle.

You'll find very quickly that two things are true with this setup:

1. You can't run many things, and even when you can you can't run multiple items at the same time.

2. Running heavy loads on your 1500w inverter burns through batteries very fast - more problematic is that it will pull down your battery's voltage so quickly that the inverter will cut out.

You need to also realize that a 1500w inverter doesn't always put out 1500w. That's a peak power achieved in testing for a marketing claim. Not a constant output.

What you are contemplating is interesting but an exercise in frustration. Plug that Laptop or Fan into the inverter - not the whole TT.

Mbtuner · 08-25-2022, 09:58 AM

We're minimalist campers. We had a popup for 19 years and learned to manage electrical use without a generator or solar. We park for days without requiring either.

The microwave runs fine on the inverter. We're not trying to prepare large meals in it, maybe just thaw something or warm up a mug of coffee that got cold. We cook and grill with propane. We heat in the morning with a Mr Buddy. Haven't run the furnace in years. We camp at altitude in the summer so we have never used A/C. We rarely have shore power anyway.

I understand that a lot of people are used to using a lot more power. I personally hate generators which a lot of people can't camp without.

We might try to watch some football in the fall, or a movie from a download. If we don't have capacity for that I'll add a battery, not a generator.

Morich · 08-25-2022, 10:33 AM

Do you have info on exactly which inverter/ charger you have? It is possible that info is online for looking more closely at what it would take to remove the charging to the battery and replace that lead with a lead from the alternate battery.

My thought might go toward a switch with heavy duty contacts that woulet you easily remove the current De lead tothe RV batteriesandadd the lead from the alternate.

It would require heavy duty to match the expected load but likely something somewhat simple like a manual transfer switch?
But knowing what you have is a first step as there are so many ways to build any electronics.