Need to upgarde charger/converter

Boon-docking what an adventure! Last summer I ran into power issues where I ran the genset for days on end and barely charged the batterys. So I want to be prepaired this summer. I boon-dock fulltime in the summer. My coach is only running 2 12v group 24 deep cycle batteries which at full charge get me about a weeks worth of power. The charger thats in here is a 50amp megnetek model 950. I need something that I can run the genset for maybe 4-6 hours a week and will keep the batterys charged with out cooking them. Randy at best converter suggested the powermax boondocker's listed here http://www.bestconverter.com/Powermax-Boondocker-Converters-_c_154.html but I am not sure which one to get. Has anyone had experience with these? Also a local shop here recommended the "Progressive Dynamics 9200" I'm not really sure what I am looking for as a good replacement so I welcome your input please!

Thank you

I can recommend the PD92XX series chargers. I am not familiar with Powermax products.

what about the amps for the 2 battery i have?

The PD products with the Charge Wizard are a very good choice. I have also dealt with Best Converters a couple of times. Very good people to deal with. Under their advice, I replaced one with a Powermax Boondocker with the 4-stage charger. I have a 60A charger that does an excellent job keeping my 2-4D's at the top. No cooking and quiet as a church mouse. Just regular battery maintenance is needed.
My 2 cents on the converter/charger.

I boondock 100%. Genny when I need it. If you are thinking about upgrading from the group 24's, that will mean additional cost. If you decide to upgrade, that could make a difference in what size charger you will need.
Think this one out before you decide and purchase.

I think I've got 4 cents invested now. 

I was a little confused. So which system are you running now? Also I have not put much thought into upgrading the batterys as I dint think I needed more juice. everyone says a week on those 24's is pretty darn good. My power usage is minimal. Mainly lights and the propane fridge. Also I am in no hurry I am hooked up until the end of april. So I am trying to do my research.

With two type 24 batteries a PD9245 should be sufficient. But you state your old one is a 50 amp charger/converter. It is better to go with the PD9255 to meet original units capacity. This will slightly increase your power draw when on shore power. The PD9255 would also support a larger capacity battery bank as well. Getting a full week out of a pair of type 24 batteries is good! Kudos to your power discipline and practices.

You said that you got a week out of your two Group 24s.  What was the voltage reading at the end of the week?

Thanks.

v33sonata said:

Boon-docking what an adventure! Last summer I ran into power issues where I ran the genset for days on end and barely charged the batterys...

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Why not run the GEN and plug in a battery charger to charge your batteries ? It would be much more performant then charging with the converter/charger.

I need something that I can run the genset for maybe 4-6 hours a week

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Ain't gonna happen. You have two Grp 24 batteries for about 170 AH of stored power. Your existing 50A charger is actually oversized for that, since those batteries cannot accept the full 50A for more than a few minutes at most. And the battery resists further charging as the charge builds up, so it takes many hours to get from around 80% charge to 100%. Above 80% state-of-charge (SOC), the charge rate is gonna be well under 10A, no matter what size or brand of charger you use. So installing a bigger charger gains you nothing. Nor does it help to use a high powered external charger.

The old Magenetek 950 is a decent charger but only single stage. You can get more charge faster with a 3 stage (or more) charger, and your batteries will stay healthier as well. The PD9255 is an excellent one of those, but those Powermax that Randy suggest are probably fine too. I have no idea about Powermax reliability and length of service, though, whereas Progressive Dynamics is a well known and respected brand.

I was told that the old charger was only putting out about 5 Amp either way and that the 50Amp rating listed on it was to run all the other 12v stuff. So how many amp charger Do I need to charge them in a timely manner and what kind of charge times should I exspect? As for how many volts the battery s are at when dead I am not sure as it was last season and I don't remember. Randy just suggested a 75Amp charger. I feel that's too big? Won't that kill the battery s or am I missing something? Sorry I'm a newbie.

A higher amp rated charger will not gain you much.
No matter the charger, the output voltage is going is going to be held at proper level to safely charge the battery. Multistage chargers will initially charge at a bulk charge rate at about 14.6 volts. The discharged battery will draw it's highest current during this phase partially because it's voltage is lower than the charger output. But as battery quickly develops some level of charge, it's voltage increases, reducing the charge current/rate. This continues throughout the various charge phases...battery voltage increasing and charge current/rate decreasing until battery is fully charged.
With a multistage charger like the PD92XX charger expect from 8-10 hours to charge a battery. Visit this site for some good info... http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery

does it not matter what amp charger I get? I was under the assumption that if I got a 60amp that 30 would go to both. But now I think I am am reading that the new chargers will only charge up to what is safe for the batterys?? so I can get 100 amp and it wouldnt matter?

v33sonata said:

does it not matter what amp charger I get?

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Yes. You need a charger that will provide sufficient capacity for initial maximum rate charging while still supporting other loads in the coach such as lights, furnace, pump, etc.

v33sonata said:

I was under the assumption that if I got a 60amp that 30 would go to both.

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It does...the output from the charger will be divided equally between parallel connected batteries.

v33sonata said:

But now I think I am am reading that the new chargers will only charge up to what is safe for the batterys?? so I can get 100 amp and it wouldnt matter?

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But, amount of current is determined by the load from the batteries. You can have a 1000 amp rated charger but the battery will only draw as much current as it's condition/state allows. Remember - charger voltage is fixed (14.6 volts) the resistance of the battery varies from low to higher as it charges. The formula is I=E/R where E is voltage (charger fixed output), R is resistance (battery state) and I is the resultant current. The resistance/charge of the battery determines how much current is drawn from the charger.
Also, it would matter in initial cost (more amps, more expensive) and during operation. The higher rated charger would place a larger load on the 120VAC shore power connection when hooked up - if you are running multiple AC items, might be enough to exceed your power connection 30/50 amps.

I was told that the old charger was only putting out about 5 Amp either way and that the 50Amp rating listed on it was to run all the other 12v stuff.

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That is not true of the 950. I suspect someone was applying a fact that applied to the old 63xx series Magneteks to the Magnetek 950, but that would be erroneous.

So how many amp charger Do I need to charge them in a timely manner and what kind of charge times should I exspect?

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Somewhere is the 50-60A range is probably optimum.  A three stage charger will produce slightly faster charge times than a single stage, but the difference is not dramatic. Charge time varies with the starting point state of charge and typically takes 12-15 hours to reach 100%. However, it probably reached 80-85% is just 2.5-3 hours. A 3-stage charger with a high amp capacity gets to that 80% level a bit faster. Beyond that level, it doesn't make much difference what charger is in use because the amp rate is just a trickle.

When the battery voltage drops to about 12.2v (with no active loads), the battery is at the 50-60% charge level.

Randy just suggested a 75Amp charger. I feel that's too big? Won't that kill the battery s or am I missing something?

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A higher rate charger simply means it is capable of producing more. It doesn't force more amps in - the battery itself pretty much dictates the amount of amps that actually flow. The charger could force the rate up by applying higher voltage, but that damages the battery and shortens its life, so no quality charger does that. Three (or four) stage chargers carefully adjust the voltage over time so that the battery gets all the amps it can take without overheating or "boiling" it.

So, buying an oversized charger is not harmful, except maybe to your wallet.

Since the charger is also a power converter and supplies 12v power to the RV in addition to charging batteries, some of those amps get used by other 12v devices. However, unless you have a 12v powered fridge running, there probably isn't a sustained demand for more than 5-10 amps of 12v power.  The various circuit boards and devices like LP detectors typically consume 2-3 amps continuously, and lighting will add about 1 amp per bulb that it lit. The furnace fan is the only large 12v power draw that runs long enough to have much impact, and that's only when heating. Therefore a 75 amp, 3-stage charger would run all your 12v power equipment and still leave around 55-60A available for charging.

Thank you that was put simple!

Glad to be of help.

Nice reply, Gary. The reason I mentioned to the OP that if a battery bank upgrade was in the near future, to think about the whole package. So money isn't wasted and the end result doesn't fit what the OP wants.