My newest electrical toy.

[SternWake]

I have another 8awg output on my Meanwell bypassing the wattmeter.  The 8awg does not cause the heating, nor the RC meter.  It is the fact it runs at maximum output until the battery voltage approaches the chosen voltage. It does not roll back the current to protect itself.

I have run both outputs into the same battery so each only carried 20 amps.  I no longer bother . The voltage drop  difference was not enough for this to be a concern.  The 'GTpower' wattmeter counts Amp hours and Watt hours as well as voltage minimum, peak wattage  and Peak amperage.  This information is so much more valuable than just an analog or Digital ammeter when recharging, and it reads closely to my clamp on meter in the  2 to 40 amp range, becoming less accurate under 2 amps

The Megawatts are said to roll back the amperage once they reach a certain temperature.  Niner reports his folds back to under 30 amps and the time at 36 amps is quite short.

Mine only gets warm at 30 amps, it gets hot at 40 amps and it holds 40 amps for as long as it takes the battery to be brought upto near my chosen absorption voltage.

The watt meter now  has Short 8awg leads with  45 amp powerpoles replacing the original 12awg aluminum wiring right to the circuit board.  The  output wiring barely gets warm.  The wattmeter itself barely gets warm at 40 amps for an hour.  With the original 12awg aluminum leads it got hot.

Here you can see the tinned 8awg wire soldered to circuit board.  The (+) cable is not even cut, the (-) has a flat wide thick shunt that the current passes through.:

The Megawatt is a tremendous value at ~65 dollars.  I spent $127 for the Meanwell taxed and delivered.  But I also get a constant 40 amps and I can push it upto 16 volts, or even 19.23 volts if I so choose. 

My extra heatsinking and fans were initially to reduce the time at which the original meanwell provided 40mm fan would run.  It is very powerful and loud, and before modifications would cycle on and off at 6 amps output.  With my fans and extra heatsinks this 40mm fan only comes on after about 10 or 15 minutes at maximum output of 40 amps, and last night this 40 mm fan shut off when the battery limited the amps to 34 at 14.5v at 85F ambient.

This was 10 amps higher than before I added the extra heatsinks at the same ambient temperature.

 

[Mobilesport]

[font=Verdana, Arial, sans-serif]Sternwake wrote[/font]

[font=Verdana, Arial, sans-serif]"MWTV is voltage measured at the MW's output terminals.[/font]


[font=Verdana, Arial, sans-serif]GTPV is the voltage measured by the GTpower meter[/font]

[font=Verdana, Arial, sans-serif]IPNV is the battery voltage as read by my IPN pro remote battery monitor"[/font]

[font=Verdana, Arial, sans-serif]Shouldn't all these voltages read the same ?[/font]
[font=Verdana, Arial, sans-serif]I mean like one reading your measuring the Meanwells output and the other reading your measuring voltage at the battery but there the same positive and negative wires but your just measuring at different locations on the same wires , I realise that one voltmeter may read a little different from a different voltmeter but your readings in the chart are quite different .[/font]
[font=Verdana, Arial, sans-serif]Could you explain where the voltmeters leads are connected to in the circuit for the three different voltage readings? [/font]
[font=Verdana, Arial, sans-serif]Thanks Stern your knowledge on this stuff is amazing. [/font]

 

[SternWake]

I answered most of these questions above on your Meanwell rsp-750-15 thread on post #39 of page 4:

https://vanlivingforum.com/Thread-I-bought-a-Meanwell-RSP-750-15?page=4

 

[Mobilesport]

@Sternwake
Looking at the Meanwells pot from the front view like you were going to use it  there's three legs
Left  center and right

Looking at the 10 turn 1K pot from the front view like your going to use it , it also has three legs ,,,, left , center and  right. 
So I assume  wire the left to the left the center to the center and the right to the right?
Is this correct?

 

[SternWake]

@Sternwake
Looking at the Meanwells pot from the front view like you were going to use it  there's three legs
Left  center and right

Looking at the 10 turn 1K pot from the front view like your going to use it , it also has three legs ,,,, left , center and  right. 
So I assume  wire the left to the left the center to the center and the right to the right?
Is this correct?

not quite.

2 of the legs are electrically connected so only 2 wires need leave the potentiometer.  Seeing the traces on tehecircuit board, or a Ohmmeter will tell you which legs  are one and the same electrically.

Only 2 wires need to run to external potentiometer. If one gets the wires wrong on the external pot then the voltage will lower when pot turned clockwise and visa versa, If so just flip the wires over so clockwise raises output voltage.

My MW potentiometer measured at at 989 OHMS and I got a 1000 OHM external potentiometer
I am not sure the 750 uses the same value potentiometer.  There will be marking on it saying w103 or something like that and one can order the correct value external potentiometer before attempting to remove it to add wires, or just add wires to its legs, if accessible.

One thing to note is the original voltage trim pot at 989 OHMS allowed a minimal voltage of 13.23
The Bourns potentiometer went as high as 1017 OHms and the minimum voltage lowered to 13.12v

I've rarely had need for more range on the bottom end, but it was nice to gain some.

 

[SternWake]

An update/bump:

I got a 1K ohm Bourns 10 turn potentiometer with turns counter and installed it in between my stress relief legs on some Zip ties, in a Gutted LED dimmer casing.  I also added another voltmeter, since I had it.

I also added a K type thermocouple to an internal heatsink.  This thermocouple can be read many common digital multimeters and some other devices.

Meanwell appears to have installed 2 temperature sensors on internal components to decide when to activate/deactivate the loud 40Mm fan.

My sensor is thermal epoxied to heat sink on left.  One of the stock meanwell sensors is on the right held to heatsink with the leaf spring.

Seems the fan consistently comes on at 103.7f and when amps taper, goes off around 98F but this latter temp varies upto 2 degrees in either direction..

The highest I have seen is 116.7 f at 40 amps output on a 95 degree day.

I had reversed the directions of the Noctua fans in every possible orientation, looking for improvement, but the original locations I chose, 60MM fan blowing inward, and 80MM outward is most effective.

...

In the following photo, I am using it as a portable charger. I removed the 4 screws holding it to my cabinet door and took it to my friend's house to top charge 2 AGM batteries foolishly bought well before they were ready to be put into use.

I have 10 AWg extension cords with 45 amp powerpoles and both 10 and 8 awg Alligator clamps, also with 45 amp Anderson powerpoles  connectors.  In this case I put my portable GT power wattmeter on second Meanwell output and ran the individual outputs to each battery individually, so I could see how much each battery was accepting at the voltage I chose, and know when to remove charger.

I do not know if there will be any more modifications.  the two heatsinks on top are designed to have 60MM fans attached to them, and I have fans which could attach easily, but honestly I don't believe it is worth the effort.

I am very happy with this Manual charger.  I can and sometimes do use in in parallel it with a 65 amp charger, but really do not need the extra 25 amps.  

Battery temperature sensors have revealed much more temperature rise than expected both when driving and charging at high or low amperage, and at high amperage via the meanwell at 40 amps output.  I find myself backing off the voltages a little bit when the battery gets near 90F.

Even after 14.7v is reached and amps  start tapering, battery temperature keeps rising( but at a slower rate) until amps are in the low single digits.

I have a 4 channel k type thermometer and can check 4 different sensors at the same time.
https://www.amazon.com/upHere-4-Cha...&sr=8-1&keywords=4+channel+k+type+thermometer

 Sensors sensors everywhere.

buwahahaaahaaahaaaaaa!!!!!

 

[SternWake]

My 4 channel thermometer is a slightly different clone, color wise. it appears very well made to me the battery cover has a screw, and they actually inset a little threaded brass insert into the plastic to accept a machine thread screw, rather than just driving a sheet metal screw into the plastic.

One can buy longer K type thermocouples inexpensively too.

https://www.amazon.com/uxcell-Meter...475726599&sr=8-8&keywords=k+type+thermocouple

The Arctic silver thermal epoxy has some very good adhesion, and of course thermal transfer properties.

https://www.amazon.com/Arctic-Silve...5&sr=8-1&keywords=arctic+silver+thermal+epoxy

 

[Mobilesport]

@ Sternwake
Love the dimmer case with the pot & the green voltmeter , damn it looks nice! !!!!!

 

[SternWake]

Thanks. My battery loves it!

 

[Mobilesport]

I was using one of those indoor outdoor thermometers but my outdoor sensor quit working so last week I went looking to replace it , I didn't end up replacing it because all  the ones they had in the store were too expensive and plus I was hoping to find one with multiple wireless sensors and a main unit like yours where it tells you the temp in the 4 zones but no luck , I like keeping one sensor in my cab side of the partition and the other in the house side , if I had more sensors I could put one by my charger and...

Here's a picture of the one I was using

 

[SternWake]

The thermometer I linked is rather large. Much larger than I expected when looking at the photos. From the very top of the Yellow thermocouple inputs to the bottom is just over 9 inches long and 3 3/8 inches wide and 1 5/8" thick. Much bigger than I suspect it needs to be, but the narrower bottom portion does fit nicely in ones hand.

It only stays on for about 10 minutes too before auto shut down.
No idea on battery life yet. Takes a 9v.