Recommendations for power station DC output Amps

[Jeremy9107]

Going to purchase a Progressive Dynamics all in one power station but figure this question could apply to any brand. In my case have 50A inlet. The PD models (4500 series) come in 60A, 75A and 90A. Believe that is in reference to DC output. Looking for advice on which would be best. Is it better just to have the higher Amp capability? Have heard that wiring has to be able to accommodate the higher Amps, but which wiring is that? Wiring between battery and DC distribution panel or all the DC circuit wiring within the trailer? Thanks.

[rmkrum]

The output rating is related to how much 12 volt power you use, and how big a battery bank you are trying to charge.

If you consume a lot of 12 volt power, like using regular incandescent lights, a lot of propane heat, etc, a higher output is useful.

Generally, in your size trailer, a 60 amp converter is reasonable. I suspect the wiring that is probably very well buried inside your trailer is just good enough for a 60 amp unit, so I'd stay with that.

If you are totally re-doing the wiring, then you can design it to use a higher output--basically heavier wires between the converter and the batteries.

[Jeremy9107]

Rmkrum thanks for advice. I’m in the middle of a renovation so have become all too familiar with all that wiring. For curiosity sake, if going with higher output like 75A or 90A, what would recommended wire gauge be between battery and distribution panel and over what distance? My battery is right next to my converter in rear of trailer but I did run wire from battery to front of trailer for a disconnect switch and battery monitor then back to converter with 6g.

[A W Warn]

I have a 60 amp converter in my 25 and 34'. That's plenty to keep charge on 2 batteries and run everything in the trailers. (fridge, furnace, lights, TV/radio). Since I changed interior lighting to LED, there is surplus capacity.

ps:
IMO, the only advantage to having a higher amperage output converter would be faster charging (less run time while using generator)

[AirMiles]

I will add a couple of observations on this topic. I have a PD4655VL converter upgrade. This is a 55Amp converter installed on the factory wiring. I only get 20A of charging at the battery from this installation even when the rested battery voltage was near 12 and in bulk mode. I’ve read that it is normal to get well under rated amps of charging at the battery.

Also, you should size your charger to meet the battery manufacturer’s recommended charging rates for your battery bank. Wet cells prefer a nice slow charge rate, AGMs can charge faster, and lithium can charge very fast. My 20A charge rate is about double my battery bank’s twenty hour rating, a “C2” charge rate. This is a good slow rate for charging my wet cells. My solar charger maxes out at 30A, a C3 charge rate.

Batteries and their chargers are a system that need to be designed in a balanced manner. You don’t want to oversize one versus the other. You also want to match the charger’s voltage in its bulk, absorption and float stages to your battery manufacturer’s recommendations. Try to balance all of this as best you can when selecting a converter. It’s very unlikely that you will find the “perfect” converter, unless it is completely programmable like many of the solar converters.

[AirMiles]

Originally Posted by AirMiles

I will add a couple of observations on this topic. I have a PD4655VL converter upgrade. This is a 55Amp converter installed on the factory wiring. I only get 20A of charging at the battery from this installation even when the rested battery voltage was near 12 and in bulk mode. I’ve read that it is normal to get well under rated amps of charging at the battery.

Also, you should size your charger to meet the battery manufacturer’s recommended charging rates for your battery bank. Wet cells prefer a nice slow charge rate, AGMs can charge faster, and lithium can charge very fast. My 20A charge rate is about double my battery bank’s twenty hour rating, a “C2” charge rate. This is a good slow rate for charging my wet cells. My solar charger maxes out at 30A, a C3 charge rate.

Batteries and their chargers are a system that need to be designed in a balanced manner. You don’t want to oversize one versus the other. You also want to match the charger’s voltage in its bulk, absorption and float stages to your battery manufacturer’s recommendations. Try to balance all of this as best you can when selecting a converter. It’s very unlikely that you will find the “perfect” converter, unless it is completely programmable like many of the solar converters.

I calculated the “C” rates wrong on the above post. Lots to remember about all this battery and charging technology. Here is a link that tells how to calculate “C” rates. https://www.altestore.com/blog/2015/...teries-part-2/

[rmkrum]

Originally Posted by Jeremy9107

Rmkrum thanks for advice. I’m in the middle of a renovation so have become all too familiar with all that wiring. For curiosity sake, if going with higher output like 75A or 90A, what would recommended wire gauge be between battery and distribution panel and over what distance? My battery is right next to my converter in rear of trailer but I did run wire from battery to front of trailer for a disconnect switch and battery monitor then back to converter with 6g.

Don't have it handy, but look for an "Ampacity" table that shows wire size, length, and current desired...should be one on the AMSolar website for sure...remember that wire length is "out and back"--as in if the run is 20 feet, figure wire size for both conductors based on 40 feet total distance.

[uncle_bob]

Originally Posted by AirMiles

I will add a couple of observations on this topic. I have a PD4655VL converter upgrade. This is a 55Amp converter installed on the factory wiring. I only get 20A of charging at the battery from this installation even when the rested battery voltage was near 12 and in bulk mode. I’ve read that it is normal to get well under rated amps of charging at the battery.

.....

Hi

Indeed less than rated current into a normal battery seems to be a fairly normal thing. I still would not *depend* on that being the case. The devices may actually be power limited and if you get to a shockingly low battery voltage .... they might put out the rated current. (twice the current at half the voltage is the same power ....).

Based on the fact that the stock breakers in an AS are rated for less than the rated output of the converter, this oddity appears to be pretty common knowledge . Since just about all converter chargers work this way ( = I know of one that *does* put out full rated current into a real battery) there must be a reason. Even the unit that actually puts out full current, at the default settings puts out less current as you get closer to fully charged.

One very real reason to "taper" the current as you get close to full charge is to keep from nuking a typical battery. If you don't have a temperature probe, you may be a bit outside the batteries comfort zone as you get close to max voltage.

Yes, it's all a bit weird, life is strange .... move on.

Normally battery size and converter size are roughly matched up. Roughly means that 50 / 55 and 60A converters all pretty much match the same batteries. If you go up to a 100A converter that would match 4 of the typical batteries rather than two of them. It also would match up with twice as much wire and bigger breakers and maybe bigger fuses (depending on how things are wired).

What does a 100A converter get you (with stock batteries) over a 60A? The 60A should get the batteries fully charged in 4 to 6 hours. The same batteries likely will be fully charged in 3.5 to 5 hours with a 100A converter ....

Bob

[oldenavy]

Originally Posted by Jeremy9107

Rmkrum thanks for advice. I’m in the middle of a renovation so have become all too familiar with all that wiring. For curiosity sake, if going with higher output like 75A or 90A, what would recommended wire gauge be between battery and distribution panel and over what distance? My battery is right next to my converter in rear of trailer but I did run wire from battery to front of trailer for a disconnect switch and battery monitor then back to converter with 6g.

Here's a link to a wire sizing chart:
https://www.westmarine.com/WestAdvis...e-And-Ampacity

For the charger application, you can use the 10% chart.

As others have said, unless you're increasing battery capacity over factory size you don't really need to spend the $$ on a larger charger.

[Jeremy9107]

This stuff can be quite confusing to an amateur. Believe the most telling thing thus far is what uncle_bob said. Battery charge time difference with upgrade to higher Amp converter would only be 0.5-1 hour. Thinking would not be worth the effort of upsizing wires or worrying that wiring is adequate so will stick with the 60A converter. Appreciate everyone's input.

[uncle_bob]

Originally Posted by Jeremy9107

This stuff can be quite confusing to an amateur. Believe the most telling thing thus far is what uncle_bob said. Battery charge time difference with upgrade to higher Amp converter would only be 0.5-1 hour. Thinking would not be worth the effort of upsizing wires or worrying that wiring is adequate so will stick with the 60A converter. Appreciate everyone's input.

Hi

Just to explain that number a bit:

Lead acid batteries go through a couple of phases as they charge up. They start out gulping current just as fast as they can get it. That's where a high(er) current converter helps. Pretty quickly they start to drop back. The converter is no longer the limiting factor. Unfortunately they are nowhere near 100% charged when this happens. They then spend a *long* time getting the rest of the way to fully charged.

One of the advantages of Lithium batteries is that they don't work the same way. To the extent there is a "taper off" period it is much quicker and it does not make up as large a chunk of the total. Simple answer - you would save a bunch of generator time with lithiums. Equally, the bigger charger / converter would be more useful with lithiums.

You *can* indeed put to big a charger on to small a battery (or battery bank). None of the combos we are talking about really get to far into that range. A true 100A on stock batteries would indeed be in the "to big" range.

Bob