48v to 12v converter question

[GlennWest]

As many know here I have a 21k 48v battery pack. Using a buck converter Chinese made 60 amp. If I am running a slide out when it reaches full out it will dim lights. I am feeding it with #4 wire. That is 48ish volts. #4 to DC supply. Do I need to up that size to DC hook up some. Short run

Edited September 29, 2021 by GlennWest

[oldjohnt]

 Yo Glenn, you sure come up with some good electrical related questions !!!

  In order to properly size the wire, here's the process I used per NEC recommendations at the time I practiced power distribution.

 Compute the MAXIMUM Continuous Current,,,,,,,,,,,Size the conductors to have a MINIMUM Ampacity of 125% of the MCC,,,,,,,,,,,Knowing the current, wire size and distance, compute the Line Voltage Drop and if in excess upgrade the wire size EASY PEASEY

If lights dim (subject to what and where they are fed from) there's excess Voltage drop caused by:

A) Battery capacity is inadequate (I doubt that one in you case lol) Theres excess Line Voltage drop 

b) Your DC to DC Converter is inadequate (I Doubt that also)

     Questions 1) How many watts is it rated??  2) Whats the max full load current of your slide motors ?? 3) What is the size of wire running to the slide motors?? OOps you said 4 Gauge that sounds plenty

c)  There's excess Line Voltage Drop due to undersized conductor  (I doubt that also)

d) The dimming lights are fed too close to where the slide motors are wired

e) The distances and limit switches and adjustments are incorrect allowing for current draw for some even if slight time even after the motors can no longer turn (near end of travel) SEE BELOW

 

 I also suspect the limit switches and mechanisms by which the motors continue to draw excess current even that of LOCKED ROTOR when they approach or reach their outer limit, yet still for some time are under power WHICH CAUSES EXTREME HIGH CURRENT  and low voltage dimming lights EVEN IF ALL ELSE IS FINE ??????  

 While my possible reasons listed above remain valid, I suspect the limit switches and mechanical/physical  considerations and/or adjustments that force the motor into lock up while still drawing current NOW THAT CAN DIM THE LIGHTS even if all else is okay

 Your distribution system/capacity and master buss and how and to where everything is wired all comes into play here.  Id say the motors alone don't draw excess current but how and when/where they are switched and all those end adjustments  and limits are causing high current near the end of travel ............

 Im NOT any slide out or DC to DC expert, I have no specs or data, and am rusty on the latest NEC, so NO Warranty, see what the other fine gents with experience related to your specific questions have to say !! Check the adjustments and max distances and limit switches relays etc that control current to those motors   THATS MY BEST PURE GUESS,  I DOUBT YOUR 4 GAUGE WIRE IS INADEQUATE OR THE PROBLEM !!!!!!!!!!!!

PS When my slides are at the end of their extension the "slip clutch mechanism" or whatever it is will chatter skip skip skip and that's when I know to release the switch which I try at the very first sign, maybe your drive mechanism or slip clutch mechanism needs adjusted so it prevents locked rotor condition extreme high current ???  Im runnin out of ideas here and grasping at straws, is it a mechanical or electrical issue? Im thinking  a mechanical or adjustment problem causing the high current..... 

  John T  

  

Edited September 29, 2021 by oldjohnt

[Randyretired]

To determine the actual amp draw a DC clamp meter is very useful.  I know you are also planning a large solar panel display.  A clamp meter is also useful to monitor solar panel output if a problem arises.  I recently found a bad MC4 connector on one of our arrays with the help of the meter.

[oldjohnt]

7 minutes ago, Randyretired said:

I recently found a bad MC4 connector on one of our arrays with the help of the meter.

Randy, Ive seen MC4 failures including ones that seem to have melted either from exposure to direct sunlight ?? or excess current ?? I'm NOT a huge fan of them unprotected on a roof.   I have used direct burial rated wire nut splices inside a waterproof junction box which I prefer, but hey that's just me.

John T  Also retired and love it     

[GlennWest]

2 hours ago, Randyretired said:

To determine the actual amp draw a DC clamp meter is very useful.  I know you are also planning a large solar panel display.  A clamp meter is also useful to monitor solar panel output if a problem arises.  I recently found a bad MC4 connector on one of our arrays with the help of the meter.

Yes need to pick me up.

[GlennWest]

Believe hydraulic issue. Will start sperate post

[Randyretired]

17 hours ago, oldjohnt said:

Randy, Ive seen MC4 failures including ones that seem to have melted either from exposure to direct sunlight ?? or excess current ?? I'm NOT a huge fan of them unprotected on a roof.   I have used direct burial rated wire nut splices inside a waterproof junction box which I prefer, but hey that's just me.

John T  Also retired and love it     

You are so right.  The MC4 connectors are not as reliable as one would hope.  This is on a temporary ground mount so I am just living with it but even though I fixed the one connector that failed there is another problem.  2 strings of 3 panels in series and one measures 8 amps the other 7 amps.  Shorted each of the solar panels read about the same.  1 amp at 100v is quite a bit of difference 

[Lou Schneider]

16 hours ago, GlennWest said:

Yes need to pick me up.

Or just measure the voltage at the output of the DC-DC converter when the slide reaches full extension.  If it dips there you've reached the converter's limit.  If it doesn't dip then look at improving the wiring.

I got this AC-DC clamp on ammeter a while back, it works great.

https://www.amazon.com/KAIWEETS-Multimeter-Auto-ranging-Temperature-Capacitance/dp/B07Z398YWF

[GlennWest]

18 hours ago, Lou Schneider said:

Or just measure the voltage at the output of the DC-DC converter when the slide reaches full extension.  If it dips there you've reached the converter's limit.  If it doesn't dip then look at improving the wiring.

I got this AC-DC clamp on ammeter a while back, it works great.

https://www.amazon.com/KAIWEETS-Multimeter-Auto-ranging-Temperature-Capacitance/dp/B07Z398YWF

Went digging through some drawers and found one. Forgot I had it. Hadn't used it since the DRV.

[GlennWest]

Finally quit raining and got to check out system. Slides are pulling 55 amps until last bedroom slide and it maxes out converter at 63 amps. That is when my interior lights go out. Actually converter is doing all it rated at. I supposed the dead battery still had decent amps but would not hold a charge. As bad a shape as battery in I figured it was doing nothing. I was wrong. Battery was bad enough I would have no 12v until stock converter charged it some. This only took about 10 minutes and then all 12v would work. So I could buy a 12v battery or invest in 3 30 amp Orions. I lean more toward converters due to the size of my battery bank. In a power failure I can run furnace for days. I intend to put in inverter and solar next year. All I have left in bills are my two cars. Start a new job next week and it is a one year project. Will have plenty of funds for this. So your thoughts, battery or converters?

[Darryl&Rita]

Battery short term, more converters long run. Put a cheap Group 31, or a pair of Costco/Walmart 6 volts. All depends on how many times you intend to move slides in and out, before you kill a slide motor with low voltage.

[GlennWest]

Well my next move will likely be there for a year. I will still, even after solar and inverter/s, need converters or battery. 3 Orion's be cost of 4 batteries. Can't stack the Chinese units. But with the battery I would be using inverter power to charge 12v battery. Bummer. 

Edited October 2, 2021 by GlennWest

[GlennWest]

What your thoughts on a lesser 12v lithium battery. I see 50ah batteries for $200ish. Don't know if I need that much ah? That would less costly route and last a long time. I would likely keep my dc/dc converter and just put a cutoff in it. Or could just wire battery to hydraulics. All else works fine with it, just not the hydraulic pump. Well after researching finding all 50ah or less is also 50amps or less. but still I can get a 12v 100amp battery for less than 3 orions. 

Edited October 2, 2021 by GlennWest

[Darryl&Rita]

Just put a cheap battery in to handle the surge load. If your current converter can handle 60 amps, let it push 60 amps. Use the battery to prop up the balance, then slowly recharge. Save up for a bigger converter bank.

[GlennWest]

11 minutes ago, Darryl&Rita said:

Just put a cheap battery in to handle the surge load. If your current converter can handle 60 amps, let it push 60 amps. Use the battery to prop up the balance, then slowly recharge. Save up for a bigger converter bank.

Wouldn't I need an isolator to prevent my 12v converter, stock in my camper, from sending charge to my buck converter going that route? 

[Darryl&Rita]

Don't know, don't have the specs of the converters, or your wiring layout. Most DC-DC converters are one way devices, but check your documentation.

[GlennWest]

States never charge the battery. And don't understand this as I do charge the 48v paks and no problem. But that is input side and not output side.

Edited October 2, 2021 by GlennWest

[GlennWest]

I was on the DIY solar rv site on facebook and asked about this. Most recommend using the Orion 20 amp converter/charger and a small 50ah or 100ah battery. The Orion would run my lights, pump, heater and use the 12v battery for the high load of hydraulics. It would also charge my 12v battery. 

[GlennWest]

https://www.amazon.com/Ampere-Time-Phosphate-Trolling-Sweepers/dp/B08K7MKRF7/ref=sr_1_1_sspa?crid=1NFDCHA5M6NJQ&dchild=1&keywords=50ah+lithium+battery+12+volt&qid=1633272810&sprefix=50ah%2Caps%2C245&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyQ0RJWTQ5NUtFTFdCJmVuY3J5cHRlZElkPUEwNDQyOTM5MU5WNDM2WTRHR1E5USZlbmNyeXB0ZWRBZElkPUEwNjQxNDMwMlBFNkUwOUc4TDA1WiZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=    I could put this in heated area in any configuration. And not much more than a lead acid battery

Edited October 3, 2021 by GlennWest

[GlennWest]

I was just reading the manual on my DeWalt system. Only trouble shooting topic on low dc power is no pump motor running. If motor running no topic list power problem. My interior lights will go out when it is trying to push out bedroom slide though. That leads me to converter not enough. Also states to change fluid every 24 months.Opps. I sure haven't done that. 

[Darryl&Rita]

4 hours ago, GlennWest said:

I was on the DIY solar rv site on facebook and asked about this. Most recommend using the Orion 20 amp converter/charger and a small 50ah or 100ah battery. The Orion would run my lights, pump, heater and use the 12v battery for the high load of hydraulics. It would also charge my 12v battery. 

That's what I'm saying.

[GlennWest]

I am tempted to buy two 30 amp Orion tr. That by figures would be no more than I have but something is wrong with my converter. Don't know what I was reading on my meter but my system is protected with a 50 amp circuit breaker. It never tripped. My lights went completely out when slides were going out. Verified this with my wife. I was outside. So I believe I have a bad unit. The 2 30 amp Orions should put out 60 amps which is 10 amps over my breaker rating. I really don't want to add more batteries. 

[Lou Schneider]

Legally, you need 12 volts to apply the trailer brakes through the breakaway switch if the trailer ever comes loose from the tow vehicle.  If this ever happens, it's easier to point at a 12 volt battery as the power source than trying to explain the brakes didn't work because they or something else caused a voltage converter to overload and shut down.

[GlennWest]

I don't have electric brakes. Valid point if I did.

Edited October 3, 2021 by GlennWest

[GlennWest]

My awning is giving problems also. I do believe it is all voltage related.