an unusual charging problem

MrWizard wrote:


he just recently got an auto transformer for Boosting low voltage shore power conditions
but it sounds like he needs to 'BUCK Down' the generator output, because of the finicky Magum

Contrary to popular belief, auto transformers, being a single winding doesn't boost low voltage conditions. They are merely designed to be connected directly to the single winding with a center tap (or anywhere between extreme ends of the winding) depending on what output you would expect at the load end.

In order to boost the voltage, you would need a buck/boost transformer which is basically a two-winding transformer with primary and secondary windings. Some manufacturers sell a product they call autoformer which hasn't gained any traction especially who are familiar with transformers.

Besides,NEC (National Electrical Code) forbids autotransformers in RVs because of potential over voltage if a winding is open (burned portion of the coil).

Yes if you were at 40% the voltage would be much lower and I would recommend running the generator early to let the solar do the long absorption work later in the day.
In these conditions Magnum should run the voltage to 14.4+

if i was at 40% I would be Down 402ampHrs
an awful lot to return
6~8 hours of generator with PD70 and NO A/C, before solar could be used for absorption

Not gonna happen in this weather
maybe in Mid-winter
but i prefer to keep my bank above 70% if possible
I can't let it charge on shore power for a week in the driveway

Hi MrWizard,

I do have my old PD 40 amp converter and could easily plug it in. I've never had both the Magnum and PD charging at once. I have used the PD with the new battery bank due to GFCI problems with the Magnum.

I might try turning off the Magnum charger and then plugging in the PD. Fortunately I have a nice hall effect meter on the PD so I'd know the net amps going to the battery bank.

The threshold appears to be 118 volts / 14xx watts.

I have seen 127 amps from the Magnum which causes it to fault. After I investigated I throttled it to 108 amps. I've seen that a few times, but not often.

MrWizard wrote:
I think PT is saying the Magnum reduces charging at 122v input (some kind of thermal ? protection for the Magnum )
turning on the water heater (using genny power not inverter) reduces the yammy output line voltage to under 120v or less and the magnum then turns on and charges the batteries
it Is an unusual situation

Don
don't you have another converter you can plug in in this situation
39amps is no where near the max of the magnum
IIRC you do have something else that will supplement that 10 amps and get back to near 40amps charge

MrWizard wrote:
while thats true for weekends or part timing
get a big bank too low and you could spend a whole lot of time in bulk mode generator run time

with a 20% 12hr use (IF i did not charge during the day) i would be at 60% before bed tonight and 40% tomorrow morning
NOT the place i prefer to be
i can do that in a bad weather pinch, and the solar does mitigate the situation making it less strenuous than the straight math, and i could limit some of the power drain at night and make (2) with no charging
put that is winter time use, cool weather and no A/C, and less cooling strain on the fridge



different routines for different folks

Yes if you were at 40% the voltage would be much lower and I would recommend running the generator early to let the solar do the long absorption work later in the day.
In these conditions Magnum should run the voltage to 14.4+

Hi Gordonthree,

I've emailed them, and now have had a phone conversation. They did not understand the original email. The tech was intrigued when he finally understood what I was "going on about"

I do not have the BMK.

Solar was contributing 3.5 amps

There seems to be some sort of threshold with the voltage. It is hot today so I am running the roof air. Voltage is 117 and wattage is 14xx. Charging is happening at 49 amps in float mode.

I don't know the menus well at all.

GordonThree wrote:
Sounds like a programming issue, I'd recommend calling in to Magnum or whatever their new ownership calls them now.

Do you have the Magnum BMK as well, or just the charging amp-meter the remote provides? I'm wondering if the actual amperage into your batteries is different than the guesstimate shown on the remote.

Next question, how many amps were the solar panels contributing to the system?

Last question, in the ARC menus, what do you have your charging mode voltage thresholds set at? Perhaps with the solar coming in and not much load, the Magnum's computer decided the batteries don't need aggressive charging based on the voltage.

My ARC will not switch into Absorb until the load gets quite high, dropping the battery voltage, and Bulk comes in at an even lower voltage. I can look in my menus later today for you if you want to compare.

In one of the menus, there is an option to force the batteries to charge, equalizer mode or something? I've never done it on my bank, I don't think AGM need an equalizer charge - maybe Mex has some words of wisdom on that subject...

while thats true for weekends or part timing
get a big bank too low and you could spend a whole lot of time in bulk mode generator run time

with a 20% 12hr use (IF i did not charge during the day) i would be at 60% before bed tonight and 40% tomorrow morning
NOT the place i prefer to be
i can do that in a bad weather pinch, and the solar does mitigate the situation making it less strenuous than the straight math, and i could limit some of the power drain at night and make (2) with no charging
put that is winter time use, cool weather and no A/C, and less cooling strain on the fridge



different routines for different folks

If I woke up to 12.5 volts I would not be running the generator.
Battery does not need to be perfectly 100% charged every day.

I think PT is saying the Magnum reduces charging at 122v input (some kind of thermal ? protection for the Magnum )
turning on the water heater (using genny power not inverter) reduces the yammy output line voltage to under 120v or less and the magnum then turns on and charges the batteries

he just recently got an auto transformer for Boosting low voltage shore power conditions
but it sounds like he needs to 'BUCK Down' the generator output, because of the finicky Magnum

it Is an unusual situation

Don
don't you have another converter you can plug in in this situation
39amps is no where near the max of the magnum
IIRC you do have something else that will supplement that 10 amps and get back to near 40amps charge

Sounds like a programming issue, I'd recommend calling in to Magnum or whatever their new ownership calls them now.

I've never had a problem charging like you describe, having to put a load on the system to make mine charge, but I've got the MS2812.

Only weird thing I notice on mine while charging, sometimes when it drops from Absorb to Float, the charging amps get stuck at exactly "15" while on the generator. I can have all my switchable dc loads off, and the BMK shows 0 amps going into the battery (per the shunt reading), yet the ARC remote shows 15 amps output on float charge.

If I turn the charger off, and on again, sometimes it'll drop to 0, or sometimes it'll stay stuck at 15.

Do you have the Magnum BMK as well, or just the charging amp-meter the remote provides? I'm wondering if the actual amperage into your batteries is different than the guesstimate shown on the remote.

Next question, how many amps were the solar panels contributing to the system?

Last question, in the ARC menus, what do you have your charging mode voltage thresholds set at? Perhaps with the solar coming in and not much load, the Magnum's computer decided the batteries don't need aggressive charging based on the voltage.

My ARC will not switch into Absorb until the load gets quite high, dropping the battery voltage, and Bulk comes in at an even lower voltage. I can look in my menus later today for you if you want to compare.

In one of the menus, there is an option to force the batteries to charge, equalizer mode or something? I've never done it on my bank, I don't think AGM need an equalizer charge - maybe Mex has some words of wisdom on that subject...