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Old 11-19-2012, 11:27 AM   #1
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1994 28' Excella
Clearwater , Florida
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INTELI-POWER: 45 or 60 amp?

TRAILER USE: (1994 classic 30')
My wife and I are starting full timers planning on 6-8 months a year of living almost always plugged in. Would like the ability to boon-dock though. Storage will have plug available for use. All lights in trailer are now LEDs. I have an aftermarket stereo with newer head unit, amp, and a strong 8" sub. We also have a solar panel on the roof which looks a bit funky and not sure if it is working.. subject for another forum search.

My CURRENT CONVERTER:
50 amp Converter Charger Series 900
Model 950-2-4 120VAC 60HZ 8 amps
12VDC 50amps max Circuit 100mA max
2 Batteries
I also use my 12V system to powerful 8" sub for movies/music

WHY CHANGE?
Considering upgrading converter to increase battery life, decrease noise, and so I have another project to do

Option A
PD9245C - 45 Amp RV Converter/Charger

- Will this supply enough power to the batteries for my usage?
- Could I use an ammeter around the (+) wire going to the distribution panel to figure out draw is less than 45 amps total while using all DC stuff at once? (don't have ammeter but may find someone that I can borrow from)

Option B
PD9260C - 60 Amp RV Converter/Charger
- Do I need to increase the thermal breaker rating to 60 amps at the distribution block?
- It appears the converter to distribution block wire is 6 Ga and only a foot or so long which should be fine. Are the only other wires to be concerned about the (+) battery poles to distribution block?
- I can shorten the wires to the 12v kill switch which seem unnecessarily long.

I'm aware of many basic concepts with electricity but I wouldn't consider myself proficient, so please err on the side of 'dumbing down' your responses.

I have contacted customer support but they are unable to answer my questions due to liability.

Sketch provided is based on what I can see and information I found in my manual.
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Old 11-19-2012, 12:29 PM   #2
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1992 25' Excella
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Exactly my question - great post

Perfect post. I'm facing pretty much exactly the same situation with my 25' Excella. I'll be closely following the responses from the people who know. I also have a call in to a very reputable local repair guy about this. I'll let you know what he says. I'm looking at the IOTA and Powermax Boondocker converters also. I'm curious about what tilted you toward PD over the other good ones. I like the fact that they are at least assembled here in the U.S.

Thanks,
Doug
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Old 11-19-2012, 01:14 PM   #3
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It's probably not possible for you to draw 45 amps, unless you've depleted your batteries and are recharging them (the exception is if you are running a large 115V inverter). The only advantage of a 60-amp converter is to provide faster battery charging, and then it only helps in the first few minutes when the charging current is high.

If you could draw 45 amps, it's only momentarily, eg, when the heater fan, water pump, hi-fi, and all your lights are on simultaneously. For these short period power requirements, the batteries can supply any extra 12V current that's needed. Granted, a 1000W inverter could pull 80 amps or so, but at that rate your two batteries will be dead or damaged within two hours. Besides, if you're talking about your converter, that means you're connected to 115V, so you're not using an inverter.

If you do run an inverter, say for a microwave to heat your coffee or scramble an egg, that's 60 amps at 12V, but it's only for a minute or two. Your batteries can supply that kind of current.

Think of your converter as the small engine that powers everything most of the time, with the batteries being the big engine that kick in when you have a temporary high 12V current requirement. Then when the high demand is over, the converter recharges (slowly) the batteries.

But I can't imagine a high current requirement on the 12V system, especially when you're connected to external 115V power.

Zep
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Old 11-19-2012, 01:21 PM   #4
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Zep, would the standard 12V wiring in a modern AS be able to handle 80 amps for any length of time. Or even 60 amps, for that matter?

The way I see it, a 60 amp might be somewhat quieter, since it probably won't turn on the fan (even at low fan speed) to cool itself as soon as a 45 amp one does, but other than that, I do not see a benefit.
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Old 11-19-2012, 01:28 PM   #5
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South of the river , Minnesota
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Quote:
Originally Posted by xitjustice View Post
TRAILER USE: (1994 classic 30')
My wife and I are starting full timers planning on 6-8 months a year of living almost always plugged in. Would like the ability to boon-dock though. Storage will have plug available for use. All lights in trailer are now LEDs. I have an aftermarket stereo with newer head unit, amp, and a strong 8" sub. We also have a solar panel on the roof which looks a bit funky and not sure if it is working.. subject for another forum search.

My CURRENT CONVERTER:
50 amp Converter Charger Series 900
Model 950-2-4 120VAC 60HZ 8 amps
12VDC 50amps max Circuit 100mA max
2 Batteries
I also use my 12V system to powerful 8" sub for movies/music

WHY CHANGE?
Considering upgrading converter to increase battery life, decrease noise, and so I have another project to do
The Parallax 900 series ferro-resonant converters do have a reputation for being loud. However, it unlikely that changing converters will improve battery life, either in terms of years of service or in terms of the amount of output the batteries will produce before having to be recharged.

Quote:
Option A
PD9245C - 45 Amp RV Converter/Charger

- Will this supply enough power to the batteries for my usage?
Yes, although you might get slightly shorter recharge times from a larger converter, which sometimes matters to people who boondock and use a generator to recharge the batteries. In that situation it reduces the amount of generator run-time required.

Quote:
- Could I use an ammeter around the (+) wire going to the distribution panel to figure out draw is less than 45 amps total while using all DC stuff at once? (don't have ammeter but may find someone that I can borrow from)
Most clamp-on ammeters are AC-only and will not work. If you find someone who has a dc-capable ammeter, then you can measure as you described. However, you may not see the whole picture since it is possible that the batteries will provide some of the power when all of the loads in the trailer are operating.

Finally, converter size should be somewhat larger than necessary to run all the loads in the trailer, in most cases, because there should be capacity available for battery charging.

Quote:
Option B
PD9260C - 60 Amp RV Converter/Charger
- Do I need to increase the thermal breaker rating to 60 amps at the distribution block?
Probably. Be sure that all the components protected by the breaker can handle the increased current.

There have been isolated reports of the cheap, self-resetting automotive breakers failing closed from a dead short, leading to fires. You might want to consider higher-quality DC breakers, or a fuse, or a larger fuse in series with an automotive breaker.

Quote:
- It appears the converter to distribution block wire is 6 Ga and only a foot or so long which should be fine. Are the only other wires to be concerned about the (+) battery poles to distribution block?
The negative wires carry just as much current, so check them too.

Quote:
- I can shorten the wires to the 12v kill switch which seem unnecessarily long.
Though a good thing in principle, that probably isn't necessary unless you believe the existing wiring poses a problem or you have to tear the circuit apart for other reasons anyway.

Quote:
I have contacted customer support but they are unable to answer my questions due to liability.
I would suggest having someone experienced present when you do the work. A qualified person who is physically present may notice hazards or potential problems that aren't clear from your description and diagram. I've had forum members damn near burn themselves--badly--by shorting out battery wires after getting advice from me.
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Old 11-19-2012, 01:31 PM   #6
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Zepp is quite correct in his analysis. 45 Amp will do just fine. I did put a 60 amp one in a GMC motorhome at one time as I wanted to have minimal generator run time for charging batteries. Even so, I found when I put it in that it would charge around 56 amps on a roughly half charged set of golf cart batteries for only about 10 to 15 minutes, and then would drop down to less than 40 amp charge and then to about 30 amps within a half hour.

I like the PD 9245 because it will run on my Honda 1000 inverter generator, and the PD9260 will not due to power factor issues (a complex thing to explain, trust me).
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Old 11-19-2012, 04:37 PM   #7
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1994 28' Excella
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Looks like I'll be going with the 45 amp. Thanks for all the information everyone.
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Old 11-19-2012, 05:38 PM   #8
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Quote:
Originally Posted by Aage View Post
Zep, would the standard 12V wiring in a modern AS be able to handle 80 amps for any length of time. Or even 60 amps, for that matter?...
The individual circuits in the 70s Airstreams are 16 and 14 gauge, which can handle about 8 and 12 amps, respectively. The blue charging line is usually #10, which can handle 30+ amps.

When you look at current carrying capability of copper wire, there are two specs, one for "chassis" wiring, which is for short runs, and one for power, or longer runs. The numbers I provide here are a compromise. For example, #16 wire can handle 22 amps max in chassis, or 3.7 amps for longer power runs. The #16 wire won't get hot enough to melt the insulation until you exceed 22 amps by a significant amount. But you don't want to come close to that, especially if the wire is in bundle of other wires that are also getting warm. You also don't want to lose voltage--so the power carrying spec is a lot lower. I think for Airstream applications, the power spec is way too conservative.

The wires you have to be concerned about are short and run between the battery(ies), converter, and the charge line. These wires should never be required to carry more than 50 amps and should be fused accordingly. The thermal fuse in the blue charge line from the tow vehicle is 25 amps.

I never use wire bigger than #10, so everything is fused at 25 amps or less, except the battery line, which is 40 amps. Wires bigger than #10 are difficult to terminate into a standard fuse block and I don't think the effort is necessary. I've never blown a fuse due to normal charging operations, even when the battery is pretty low.

Zep
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Old 11-19-2012, 10:30 PM   #9
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Thanks for the explanation, Zep.

From what you are saying, there could be no real need or benefit from taking a 60A one over a 45 amp.

Case closed!
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Old 11-20-2012, 07:39 AM   #10
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I put a 60 amp in our '95 that also had the 50 amp converter originally. Works great for me.

Tip: Get shorter screws no matter which model you choose. I'm pretty sure I almost put a hole in our spare tire when I put the new screws in the floor for the converter. Oops! If you crawl underneath that area, you'll see the old screws poking through.
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Old 11-20-2012, 10:20 PM   #11
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I could be wrong but I was under the impression that you had to deduct all the other 12v usage ( furnace , water pump , lights , stereo , etc .) from the converter output amps to determine what is left over for charging amps . In addition it would make a difference whether you have 1 , 2 , or 4 batteries that you are trying to charge .
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Old 11-20-2012, 10:52 PM   #12
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Unless you have 4 deep cycle batteries, I think the 45 amp unit will work OK. The "optimum" charging rate for deep cycle batteries is C/8, or the aH battery rating divided by 8. The best charging rate for a single typical 105 amp-hour battery is 13 amps. Of course you can go higher, but you might start to overheat the battery.

On the other hand, the PD60 converter has more output taps, which might be convenient depending on your wiring scheme. For example, you can run one set of wires to your batteries and another pair to you 12V distribution panel. Might save a few wire terminations.
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Old 01-08-2013, 11:59 AM   #13
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1994 28' Excella
Clearwater , Florida
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Thanks for everyone's help. I decided to post a "how to" video guide found in the link below. Any comments or suggestions welcome!

http://www.airforums.com/forums/f449...ml#post1246696
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