Magnum MS4024PAE vs. MS4448PAE

Re: Magnum MS4024PAE vs. MS4448PAE

Does he need 24 VDC for anything (there are more 24 volt small water pumps, lights, and appliances--such as for long haul trucks/boating--Than for 48 volt systems).

I don't like parallel battery banks--So keeping the paralleled battery strings to 2-3 maximum is my personal choice. There should be a fuse/breaker per string for safety.

Look at generator to battery bank charging capacity (5% to 13% typical range, ~25% recommended maximum charging current--Although AGM will take more current than flooded cell). I like to have the minimum size generator needed to keep fuel efficiency high (and fuel costs low, and minimum storage/having to hunt for fuel in a power emergency)--I believe the Magnum inverters are programmable for maximum AC power rating of AC power source (generator, feed from grid). Make sure you get the "right" remote meter (there is a basic and advanced type meter--Not sure if the basic can program all the needed software settings or not, need to adjust charging voltage/float/no equalization voltage for AGM).

Some other options to think about--The remote battery temperatures sensor option (not sure if RBTS comes with inverter or extra cost option). And a Battery Monitor (especially helpful for AGM which you cannot measure specific gravity because they are sealed). Magnum does have its own battery monitoring system (and other products)--Not sure if it is same better/worse than a stand alone Monitor.

Otherwise--4kW inverter is pretty good sized--Does he need that much power? And what AH is/will be the battery bank?

If he ever plans on adding solar, there are various pre-wired "E-Panels" to make things a bit easier/cleaner.

-Bill

Re: Magnum MS4024PAE vs. MS4448PAE

Sounds pretty well balanced... A 400 AH @ 48 volts is good for about a 4kW inverter/charger... 800 AH @ 48 volts would be good for up to an 8kW inverter/charger (and good for 8kW/16kW surge ratings).

The 48 volt version has a 60 amp battery charger--Which would pull from the genset (maximum rating):

• 60 amps * 59 volts charging * 1/0.95 power factor * 1/0.85 charger eff = 4,384 VA (good match for a 6.5kW genset)

And a 60 Amp charger would be good for a rated battery bank of:

• 60 amps * 1/0.05 rate of charge= 1,200 AH maximum battery bank
• 60 amps * 1/0.10 rate of charge= 600 AH nominal battery bank
• 60 amps * 1/0.13 rate of charge= 462 AH maximum "good practices" charging rate
• 60 amps * 1/0.25 rate of charge= 240 AH maximum "don't exceed unless you have a very good reason" rate of charge

The above numbers are recommended rules of thumb for Flooded Cell battery banks--AGM batteries have much higher current limits and much lower self discharge--But there is not really much reason for designing a "balanced" Off Grid / Backup up system for AGM only unless it has special needs (UPS systems are designed to drain an AGM battery bank in 15-30 minutes until the computers can be shutdown and/or backup fuel power generators are brought on-line).

If he ever decides to go with solar--Having a "smaller" battery bank and a (by ratios) "larger" solar array (i.e., 10% to 13% rate of charge) can help keep costs down (smaller battery bank to replace every 3-6 years for AGM) and a smaller array (even a 400 AH 48 volt can take a pretty good sized array):

• 400 AH * 59 volts charging * 1/0.77 panel+controller derating * 1/0.10 rate of charge = 3,065 Watt array "nominal"

Tall trees can be a "temporary" situation... Our neighborhood lost many of its trees over the last 50 years--Roads are hard on tree roots and having 200 foot trees around homes on 50-100 foot lots means that cars and homes were being "bisected" every few years when a heavy wind/rain storm rolled through.

If he has more land--Can he put the array within a several hundred foot radius of the home and get some good sun?

Also, if he has grid and this is purely for emergency/backup power--He could drop to 5% rate of charge, be a bit conservative about power used during the day, and still have a reliable/solid system.

Anyway--My 2 cents worth of advice.

-Bill

Re: Magnum MS4024PAE vs. MS4448PAE

Good Catch Mtdoc!

Note to Wxboy--4 batteries in series for 48 volts, vs 2 in series/2 in parallel, vs 4 in parallel (assuming all 12 volt batteries)--Will all store the same amount of total energy... It is just moving from 24 volts to 48 volts with the same batteries--The voltage rating doubles, the AH rating 1/2's... And the total energy storage is still the same (and the current will be 1/2, allowing smaller wire/longer wire runs because of the higher battery bus voltage).

Thank you,
-Bill