House battery project help needed

[M Rose]

This isn’t exactly Overland related, but my design idea (concept) could translate to an Overland build project.

I live full time in a camp trailer at an RV/Trailer Park, so I’m hooked up to shore power 24/7. While this is great because I have converted everything to either run on 110 AC and/or Propane, I have ran into a small problem. I have dirty 12v power. The only thing running 12v is my amateur radio equipment. I have 60mhz current flowing through my 12 volt system. A clean 100 amp power converter is about $200.00 and then I still would need some kind of charge controller to go along with it.

So my idea is to find a “Normally Closed” 12 volt Solenoid that when engaged would cut my dirty power converter off, and let me run my radios straight from the batteries. When the Solenoid disengages it would then allow the batteries to charge once again.

My problem is finding a simple normally closed battery isolation solenoid that can handle up to 100 amps continuously.

 

[DignTRDoffRoad]

I'm not sure this would help, but I had to wire a solenoid up for a handicap van, using a regular house door alarm contact on sliding door, so that when the door was closed the contacts on the alarm switch would open and solenoid is open, when the door was open the door contact would close and activate the solenoid, this might give you some idea to make a normally open solenoid work instead of looking for a normally closed, the reverse was in the door alarm contact that was the trick, just something to think about.

 

[M Rose]

I'm not sure this would help, but I had to wire a solenoid up for a handicap van, using a regular house door alarm contact on sliding door, so that when the door was closed the contacts on the alarm switch would open and solenoid is open, when the door was open the door contact would close and activate the solenoid, this might give you some idea to make a normally open solenoid work instead of looking for a normally closed, the reverse was in the door alarm contact that was the trick, just something to think about.

No, it needs to be normally closed or a latching solenoid because it’s going to stay in the closed position longer than open… open for 2-6 hours per week… and closed the rest of the time… in other words I will let the charger/maintainer in the power inverter do its hob 90% of the time… only when I’m running my radios do I need to disconnect the charging power from the batteries.

The best way would be to use a knife switch (or battery disconnect switch), but I want the ease of flipping a switch on my radio panel to isolate the house batteries while running the radio equipment.

 

[DignTRDoffRoad]

Here is a 200amp continuous solenoid you could just wire a on off toggle, turn it on when needed and off when not, could this possibly work

Advance Auto Parts - Down for Maintenance

 

[M Rose]

Here is a 200amp continuous solenoid you could just wire a on off toggle, turn it on when needed and off when not, could this possibly work

Advance Auto Parts - Down for Maintenance

Except islets normally open… which means since it will be “on” 90% of the time it will heat up and either fail or cause a fire… it HAS to be a Normally Closed Single Through Relay or Solenoid. I know they make them, I’ve installed them before, but I do t know where we got them.

 

[DignTRDoffRoad]

Yea heating up is a real issue, I used a twist switch on a diy portable solar generator to separate the batteries from my inverter when not in use ( just peace of mind) something similar to this switch

https://www.etrailer.com/Accessories-and-Parts/Bulldog-Winch/BDW20248.html

Might see about high amperage DC contactors, I'm familiar with them but mostly in an N.O. contact situation.

 

[M Rose]

Yea heating up is a real issue, I used a twist switch on a diy portable solar generator to separate the batteries from my inverter when not in use ( just peace of mind) something similar to this switch

https://www.etrailer.com/Accessories-and-Parts/Bulldog-Winch/BDW20248.html

Might see about high amperage DC contactors, I'm familiar with them but mostly in an N.O. contact situation.

I’ve also used those battery disconnect switches in the past… and it might be what I will end up having to use… really don’t like the idea of climbing under my trailer in the middle of winter to turn on and off the batteries… but at this point that seams to be my only solution other than paying a couple hundred bucks for a clean power supply.

 

[Sparksalot]

Try mechanically held contactor. I bet grainger has them.

 

[Road]

I'm no electronics wiz--far from it, actually, but how about this one, @M Rose :

Mercury Relay - Hg Relay - Normally Closed - Single Pole - 100 AMP - 12 VDC

www.mdius.com

Says it's "available in the single, two, three & four pole models." I don't see a price, though.

spec sheet:

https://www.mdius.com/pdf/SpecSheets/relays/100NC-12D.pdf

.

 

[M Rose]

Thanks @Road… those relays would work in a high voltage situation…not mine… and the cost of the part isn’t worth the means for this application.

I found a relay that might work… I have a message in to RedArc to see if their voltage sencing relay can have the cut off voltage changed. Their relay turns back on if voltage falls under 12.5 volts… I need to be able to drain below 12 volts. So we will see what they say…

I also found a “Glow Plug” controller that would work as well if I took it apart and swapped sprung locations.

 

[M Rose]

Try mechanically held contactor. I bet grainger has them.

The ones I found were also for AC use… and again I have to go to the source to turn on and off the contractor.

 

[Road]

Thanks @Road… those relays would work in a high voltage situation…not mine… and the cost of the part isn’t worth the means for this application.

I found a relay that might work… I have a message in to RedArc to see if their voltage sencing relay can have the city off voltage changed. Their relay turns back on if voltage falls under 12.5 volts… I need to be able to drain below 12 volts. So we will see what they say…

I also found a “Glow Plug” controller that would work as well if I took it apart and swapped sprung locations.

.
Maybe @REDARC_Ryan will chime in here. . .

He's gonna get tired of me paging him... ha!
.

 

[REDARC_Ryan]

Thanks @Road… those relays would work in a high voltage situation…not mine… and the cost of the part isn’t worth the means for this application.

I found a relay that might work… I have a message in to RedArc to see if their voltage sencing relay can have the cut off voltage changed. Their relay turns back on if voltage falls under 12.5 volts… I need to be able to drain below 12 volts. So we will see what they say…

I also found a “Glow Plug” controller that would work as well if I took it apart and swapped sprung locations.

Hi M Rose,

Did you figure it out? Shoot me a message if you need anything!

 

[M Rose]

Hi M Rose,

Did you figure it out? Shoot me a message if you need anything!

I’m still looking for the correct relay/solenoid. All the ones I’m finding are normally open.

 

[REDARC_Ryan]

Hi M Rose,

Did you figure it out? Shoot me a message if you need anything!

I’m still looking for the correct relay/solenoid. All the ones I’m finding are normally open.

Let me ask around the HQ to see what I can find.

 

[M Rose]

Let me ask around the HQ to see what I can find.

Thanks

 

[REDARC_Ryan]

Thanks

Hi M Rose,

Unfortunately all of our solenoids are normally open. If you could draw out a diagram of your system, my in house guru said he would be happy to go over some alternatives for you that we may have to offer? Let me know, I can set something up.

 

[M Rose]

Hi M Rose,

Unfortunately all of our solenoids are normally open. If you could draw out a diagram of your system, my in house guru said he would be happy to go over some alternatives for you that we may have to offer? Let me know, I can set something up.

All of the white spikes in the second picture is the DC Power converter and RV load when my house batteries are connected to my Power Converter and RV Load.

When I isolate the batteries from the RV Load and the Power Converter I get picture 3. As you can see the DC voltage spikes disappear.

Since my radio equipment is only used a couple of hours per day, but the rest of my RV Load is needed 24/7 I need a way to disconnect the batteries for a short period of time. I am afraid that using a normally open solenoid will generate too much heat if the circuit is closed for 22 hours per day 7 days a week, 52 weeks a year.

Another solution I have would be to buy a different power converter which would eliminate all the noise, but the power converter I need is around $200 where I’m hoping to find a solenoid for under $50.00. Another solution would be to buy a 12v power supply, but then I’m using AC voltage to get DC voltage I already have access to, and the price is the same as a Power Converter

Last solution is I keep doing what I have been doing and go outside and disconnect the batteries from the RV Load every time I want to use the radio, then rehook the batteries to the RV load when I’m done using the radio. This just becomes a pain because I use the radio mostly at night and playing with batteries in the dark is not fun.

 

[M Rose]

I’ve finally found my solution. I need to make a “Flip-Flop” Latching relay circuit, I’m still looking at what relays I need to use. But should be starting this project soon. I’m tired of my radio battery during on me or forgetting to unplug the battery from the house when I’m operating… having the controls inside my shack will make life so much better.