AC to DC converter

[mcarden75]

I was looking at purchasing a new converter and found one on Amazon called IOTA Engineering Converter and Charger that is running at 45 AMPS. Do you think that would be enough to power a 30 AMP motorcoach? I am looking at replacing it for a 3 stage converter charging system. What I think is weird, my coach has a series 950-2 which is a 50 AMP system. Maybe I should get a 55 AMP setup. What are your thoughts?

Here is the link of what I am looking at: https://www.amazon.com/IOTA-Engineer...charger+55+amp

[Kiawah]

First, don't confuse 30amp motorhome and 45amp converter/charger.

- The 30amp reference, is to the 120v "AC" shorepower and input to the coach. That 30 amp max current powers all of your 120vac devices (e.g. A/C, TV's, Mwave, Hot water heater (assuming dual heat mode w/propane) etc). It also powers your converter, which has a purpose to recharge your 12v batteries.

- The converter has a rating, in this case 45 amps, which is the maximum "DC" current at 12volts. The 12volt DC items are your lights, furnace, etc.

- So an analogy is to consider your 12 batteries a water tower. The converter fills up the water tower, and when it is full it shuts off. If it's morning in a town and everyone showers then the there is a LOT of water being drained out, much faster than the pump can refill. But because it's a resevoir, your batteries provide the power to the devices. Over time in periods of lower usage, the converter fills the battery back up (similar to how a water pump would slowly fill the water tower reservoir back up).

- Whether it's large enough for your coach, depends upon how big your battery reservoir is, and how much power you use, and how often you use it. Clearly a good indication is how large your old converter is, and whether you ever had periods of time when your batteries got low.

- You can look up how much DC current your refrig uses, how much current your furnace uses, and how much current your inverter uses (if you have one). Figure out how long they run, and then determine how long your converter would be able to charge when you have power.

[mcarden75]

Originally Posted by Kiawah

First, don't confuse 30amp motorhome and 45amp converter/charger.

- The 30amp reference, is to the 120v "AC" shorepower and input to the coach. That 30 amp max current powers all of your 120vac devices (e.g. A/C, TV's, Mwave, Hot water heater (assuming dual heat mode w/propane) etc). It also powers your converter, which has a purpose to recharge your 12v batteries.

- The converter has a rating, in this case 45 amps, which is the maximum "DC" current at 12volts. The 12volt DC items are your lights, furnace, etc.

- So an analogy is to consider your 12 batteries a water tower. The converter fills up the water tower, and when it is full it shuts off. If it's morning in a town and everyone showers then the there is a LOT of water being drained out, much faster than the pump can refill. But because it's a resevoir, your batteries provide the power to the devices. Over time in periods of lower usage, the converter fills the battery back up (similar to how a water pump would slowly fill the water tower reservoir back up).

- Whether it's large enough for your coach, depends upon how big your battery reservoir is, and how much power you use, and how often you use it. Clearly a good indication is how large your old converter is, and whether you ever had periods of time when your batteries got low.

- You can look up how much DC current your refrig uses, how much current your furnace uses, and how much current your inverter uses (if you have one). Figure out how long they run, and then determine how long your converter would be able to charge when you have power.

So even though my coach is a 30 Amp system, then the 45 Amp would be the best option. My 950-2 which is 50 Amp is charging at a rate of 13.4 volts and the batteries are getting 13.2 volts. I just don't want to put a 55 Amp and fry everything including my power cord. I do have a 30 Amp surge protector inline.

[Kiawah]

So even though my coach is a 30 Amp system, then the 45 Amp would be the best option. My 950-2 which is 50 Amp is charging at a rate of 13.4 volts and the batteries are getting 13.2 volts. I just don't want to put a 55 Amp and fry everything including my power cord. I do have a 30 Amp surge protector inline.

There is 'approximately' a 10:1 correlation between 12v DC amps, and 120v AC amps.

If the converter delivers 55 amps @ 12vDC as it's output, then I would expect it to consume approximate 6 amps @ 120v AC as input. There are converter losses as it's not 100% efficient, and it makes 13.5 volts, so it might actually consume like 7 amps or so. It consumes 7 amps @ 120vac, to make 55 amps @ 12vdc. Get the manufacturers technical documentation of the product you are interested in, and look at it's specs, it should give you the total max input consumption.

Just to tie it all together, since your coach has 30amps max of 120v AC coming in, that converter could use up to 7 amps of the 30amps, leaving 23 amps for other 120vac devices. If your AC uses 15 amps, then you would only have 8 amps left.

A converter that delivers 45 amps of 12vDC as it's output, I would expect it to consume approximately 5-6 amps of 120vac.

Note: a converter will not always consume the maximum. It should have a minimum consumption like in the neighborhood of an amp or so, when it is float charging a set of batteries that are 100% charged up. Then it would have up to the maximum consumption based on how much it is being required to deliver.

Just find the product technical spec sheets.

[Gary RVRoamer]

So even though my coach is a 30 Amp system, then the 45 Amp would be the best option. My 950-2 which is 50 Amp is charging at a rate of 13.4 volts and the batteries are getting 13.2 volts. I just don't want to put a 55 Amp and fry everything including my power cord. I do have a 30 Amp surge protector inline.

You can't "fry" anything just because the converter has a higher amp capacity. As long as the charger controls the voltage properly, the battery and the wiring will only take the amps its needs.

Your old converter/charger is a single stage with a max 50A capability at about 13.5 volts. The Iota DLS 45 is a bit less max, so the DLS 55 would be a better choice. However, 99.9% of the time your charger will be running at well under the max rated amps, so the difference is not really significant. Rarely will you even need the 45A, let alone 55A.

[mcarden75]

Originally Posted by Gary RVRoamer

You can't "fry" anything just because the converter has a higher amp capacity. As long as the charger controls the voltage properly, the battery and the wiring will only take the amps its needs.

Your old converter/charger is a single stage with a max 50A capability at about 13.5 volts. The Iota DLS 45 is a bit less max, so the DLS 55 would be a better choice. However, 99.9% of the time your charger will be running at well under the max rated amps, so the difference is not really significant. Rarely will you even need the 45A, let alone 55A.

Awesome. I appreciate that. The difference between the 45 and 55 is about $30. I was thinking I had a 1 stage charger. Any advice on the install or just negative, positive, and plug it in?