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How to test Magnum temp sensor?

STW

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Sep 16, 2021
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I have a Magnum MM1212 inverter/charger. The manual says it’s supposed to charge in Bulk to 14.6v and then switch to Absorb and hold that voltage for 120 minutes (based on my 210ah battery back size). I have the battery temp sensor connected and it will lower voltage based on battery temperature @ 75 degrees).

I noticed I only get to 14.1v no matter what the temp is. Does anyone know if you can ohm the BTS and what correct values would be?
 
Just measured one at 106k @ 60deg F has been sitting, from older MS4024AE.......Magnum is one size fits all units
Pins 2 to 3, middle pair, its just a resister, DVM no problem
 
Do you have the magnum remote, I think with that you can set the charge volts and amps, I do not use my magnum to charge very often. I have very good charge controllers to do that so I never installed the BTS on the magnum
 
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Just checked my ME-ARC manual, the voltages are presets unless you scroll down to menu 5 CUSTOM so change battery type to CUSTOM, then the next menu will allow you to set bulk, adsorb, float, and equalization voltages. If you dont have a remote and can borrow one the Magnum will remember the settings that you entered until you remove DC input from the inverter. Notes do say that the inverter must have the enabled software, That is Magnum saying that very early models do not have that feature but if your unit is anywhere near new then it does include that, mine has been in service for 20 years or so and it is settable. It is not my every use inverter, just for my big jobs

<EDIT> the MS1212 is very much a newer model and would be programmable
 
Nope I don’t have the newer remote. RV came with a simple MM-RC remote that only allow you to turn on/off. It seems my inverter setting somehow does not match the factory default (according to manual). Manual says absorb should last 120 minutes, but mine lasts 90 minutes. Manual says charge volts at 14.6, but mine at. 14.1.

I email Magnum but they said not much they can do unless I have the better remote. I can’t even figure out the inverters firmware without the remote… ug!
 
Im not familiar with the small magnums, mostly deal with the MS series 4kw units, mine is 24 volts to 120/240 and may well have more features than your series. There are two remotes for mine , the ME-RC which can set about 50 settings or functions and the ME-ARC which can do do a lot more, so yours is a much more limited unit

Magnum does have an amazing matrix of models that all have different capabilities. I have downloaded a dozem model matrixes as to which model can do what, some can even sync with shore power to use both shore power and inverter power together.

Magnum support does respond but parts, boards are pricey but excellent hardware

I borrowed a remote and figured out what software that i had ,

At Magnum we have answers for your problems for $$$
 
Magnum support just replied and informed me that the MM-RC remote is set for an AGM2 battery type. It lowers the Absorb to 14.5 and Float to 13.5.

I wonder who brilliant idea it was to do that? Fleetwood is shipping their coaches with Lead Acid batteries, but the charger is set for AGM batteries. There is no way to alter the MM-RC parameters. These voltages are also impacted by the temp sensor.
 
To program a Magnum you need the Magnum remote with programming ability....

OR you need to pay a dealer to do that for you.....
Skip that, motorhome dealers are not smart enough to do that....

The MM-RC is a remote on/off switch......it is a on/off switch....it is not the programmer

The ME-RC is a remote programmer........for basic functions

The ME-ARC is a remote programmer.......for advanced functions.......for the very advanced ME-XXXX-PAE and similar models. Your unit does not have advanced functions.

The Magnum Inverter/Chargers need to be programmed on installation. To do this you need the manual and the programmer. The Magnum defaults to a 400 a.h. battery and WILL COOK a smaller battery.

Get the battery charge data from the manufacturer of the battery, DO NOT USE generic charge data, get it from the source if you want decent life from your battery, guesses don't get it...get the bulk, adsorb, and float settings from the horses’s mouth....the manufacturer of the battery....no exceptions.

SUGGESTION....

Go to solar-electric.com (Northern Arizona Wind Sun)

search your EXACT model number

Go to the page where it is sold

Scroll down, you will see a place where you can download the complete user and service manuals.

Get the manual

Search for ME-RC remote control, buy it.

download the manual for the ME-RC from the same page as the remote is sold on

Follow setup instructions....

enter data

The Magnum defaults to maximum battery charge, set as approiate for the battery as installed...not more than 20% of rating of battery.....i.e. 100 a.h. battery 20 amps maximum charge....200 a.h. battery 40 amps max.....etc.
You will need to scroll down past all battery settings to “CUSTOM” or “USER TYPE” to really set anything...

When you disconnect the batteries and the remote all programming is lost, unit needs to be reprogrammed...

The manual says different that the Magnum has non-volitable memory.... Mine goes stupid when battery is disconnected for service.........Either Magnum is stupid or my Magnum inverter is stupid....

I do not have an MM model , I have the MS-4024-AE I have had to reprogram it several times as it cant seen to remember the inputted data...

Dont shoot the messenger.....I did not design this unit.


DISCLAIMER.......I have no ties to NAWS, only a customer of the most helpful, informed solar dealer....they even take calls and do support what they sell.....
 
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