Magnum Inverter/Charger Design Tradeoffs

MEXICOWANDERER wrote:
Magnum is not TRACE

This is not the 1990's, labor, material and taxes are cruel in the USA today

A really nice 2,500 watt inverter charger would cost $5,000.00 USD.

A really nice inverter charger would include a TWO HUNDRED AMPERE rated high frequency charger protected against under frequency, and would have simple adjustments to tweak stage voltages and time retained at end of stages. Two optional temperature sensing inputs, selectable and freakin' ADJUSTABLE

Keep dreaming

Don't know where you got your figures, but at least since 1990 to about 2003, the COST of a quality RV designed Inverter/Charger was about $1 per watt. Now the cost is about .50 a watt or less. Doug( I installed a LOT of 2000/2500 watt Inverter/Chargers during that time period).

CA Traveler wrote:
And the Custom setting option is also more $$$.

I discovered all of this when I noticed that the charging wasn't the maximum on the gen which was a few volts low. Prior to installing my battery monitor I wasn't aware of the limitations.

So I started this thread so that others could be informed since this information is not part of the documentation.

My 2 units were installed by Monaco and I suspect that it was a good cost trade off for them.

Ahh good point, you need the "Advanced" remote to program a custom battery type.

When I bought my MS2812 I was able to find a bundle with an attractive price which included the BMK and the ARC.

I have not had any charging voltage related problems, verified with a DMM. My inverter and batteries (agm) are in the same bay, connected with short runs of 4/0 wire.

And the Custom setting option is also more $$$.

I discovered all of this when I noticed that the charging wasn't the maximum on the gen which was a few volts low. Prior to installing my battery monitor I wasn't aware of the limitations.

So I started this thread so that others could be informed since this information is not part of the documentation.

My 2 units were installed by Monaco and I suspect that it was a good cost trade off for them.

May as well move back to Victron.

GordonThree wrote:

CA Traveler wrote:

2. The DC amp display is estimated on the AC input current and not on the actual DC current. For example my unit will display 100A when in fact it is charging at 80A.
3. A battery voltage sense for the charger capability is not possible.

Magnum wants you to buy their add-on battery monitor module so they can squeeze some more $$$ out of you. The BMK gives you a 500A shunt to measure DC current in/out of the battery down to the milliamp level. It also enables a bunch of other features.

Not sure I understand point #3 ... are you talking about state of charge estimation using the battery voltage? I think there are battery voltage based "rules" you can program into the charger if you are using the advanced remote, another up-sell from Magnum

Voltage sense would be a pair of small wires from the Magnum to the battery so that the Magnum knows the actual battery voltage.This would improve the charging and inverter low voltage shutdown in cases like mine where the unit is far from the batteries or cases where the wiring should be larger gauge.

My unit has the capability of selecting different battery types with different voltage points.

GordonThree wrote:

CA Traveler wrote:

3. A battery voltage sense for the charger capability is not possible.

Not sure I understand point #3 ... are you talking about state of charge estimation using the battery voltage? I think there are battery voltage based "rules" you can program into the charger if you are using the advanced remote, another up-sell from Magnum

I think he's talking about remote battery voltage sensing, not sensing the charger voltage output at the charger end. In theory they are the same for zero resistance charge cables, but for long small diameter charge cables and high currents, the voltage at the charger output could be much higher than the voltage at the battery. You want the charger to control the voltage at the battery, not the voltage at the charger end of the cables.

Thanks for the good explanation on increasing the voltage.

I would just add on the VEC1093DBD for another 40amps on top of what that charger does near 80amps to get about 120amps. The generator is plenty big enough to run both chargers, unlike a small portable gen, which could not.

If you already have the portable charger anyway, say as a back-up spare "just in case," then no extra expense involved at all.

CA Traveler wrote:

BFL13 wrote:
Does the Variac's voltage adjustment make up for the poor wave form of the built-in gen being the cause of the apparent lower voltage? IE, even with a higher voltage, would it still be a poor wave form, so the charger still would not do full amps?

Since it's a basic autoformer I would expect minimum wave form change.

The Variac won't change the wave shape much and will heat up with a really bad wave shape. Also, a Variac is not what most RV owners think of when you say "Autoformer." A Variac is an adjustable autotransformer. An autoformer is a regular transformer with two different windings(really a buck/boost transformer) hooked up as an autotransformer. All the current flows through the windings of the Variac, so you'd need a high current variac. The pictured variac is a 3 amp variac. You'd need a 10A variac at least and that would be about $150. A 10% boost 60amp/ 20% 30amp buck boost transformer would cost you under $100. The buck boost transformer has small gauge wires for the input (carrying max less than 30A) and dual heavy gauge wires for the output capable of carrying 30A. The difference is that in the autoformer/buck-boost, all the current is not carried by the primary. In the variac, the primary and secondary wiring are the same (it's an autotransformer, so there is no true secondary wiring) and the wire diameter is not enough to carry the max current.

Depending on your charger output current, you might not need 30A or 60A (the buck boost can be wired either way), but a buck boost transformer would still be the cheapest way to go.

CA Traveler wrote:

2. The DC amp display is estimated on the AC input current and not on the actual DC current. For example my unit will display 100A when in fact it is charging at 80A.
3. A battery voltage sense for the charger capability is not possible.

Magnum wants you to buy their add-on battery monitor module so they can squeeze some more $$$ out of you. The BMK gives you a 500A shunt to measure DC current in/out of the battery down to the milliamp level. It also enables a bunch of other features.

Not sure I understand point #3 ... are you talking about state of charge estimation using the battery voltage? I think there are battery voltage based "rules" you can program into the charger if you are using the advanced remote, another up-sell from Magnum

"CA Traveler wrote:

Another surprise to me was the high standby current (0.25A) with no shutoff capability."


who leaves an inverter/combo unit turned ON in storage when there is no shore or charging options ?