Community Forums

woodburner · 03-21-2009, 03:48 AM

Is there any benefit to switching to a 75 amp converter when replacing the OME 55 Amp converter?
Or is it better to stay with the 55 amp altogether?

I'm considering replacing the one on our Everest because of the lights dimming when a number of them are turned on along with a fan etc...The battery is good so I know that's not the issue; so I thought the converter might be on its last leg.

Is Progressive Dynamics a good name brand? Thanks for any responses because when it comes to the power end of this stuff I am lost!

Hitchhiker · 03-21-2009, 06:11 AM

It's possible the lights are dimming due to some high resistance electrical connections and/or undersized wire gauge for the amperage being drawn.

John-D · 03-21-2009, 08:33 AM

This is a mixed question since you have not said how big your batteries are:

Xantrex says for most battery types (Gell and Lifeline AGM are the major execptions) the proper re-charge maximum rate is around 30% C (Capacity) so if you have a 80 amp hour battery your 55 amp box is already too big, two 80 amp batteries the 55 amp is about right Now if you have say a pair of Interstate U-2200 six volt golf car batteries.. 55amp is good, but 75 amp will re-charge them faster (I would not go much bigger than that) That's (Depending on who you listen to and when) between 20 and 235 amp hours.

Now.. If you have lifeline AGM's they can take up to 300% c so clearly the bigger the converter the better converter the converters are bigger at converter king. (ok Ok, that last is a pun) but you get the idea, a 100 amp Lifelien can take up to 300 amps per their web site so the larger converter is better

Half Dimes · 03-23-2009, 12:40 PM

I expect your original converter isn't a multi-level type (one that regulates the charge level). That's a good reason to get a PDI or other similar that reduces the amount of charge when the batteries are up to full charge. This helps to not boil the batteries dry if not checked periodically.

As to the right size, I went from a 45 amp to a 60 amp on our previous rig when I added two 6 volt batteries. I also replaced the standard converter on our new rig with a multi-level. Rule of thumb I've heard is that the converter amp rating should be 25% of the full amp capacity of the batteries (60 amp would cover up to 240 amp lead acid batteries). All my reference materials are buried right now due to some remodeling. If my memory on this is incorrect, I'm sure someone will chime in.

Paul R. Haller · 03-23-2009, 12:46 PM

Umm, I don't think I'd rush to replace the converter just yet. First as Hitchiker said, check all your connections both at the battery and the main panel DC location. Then check the connections from the converter to the battery. Connect the negative probe to the chassis and the positive at every connection. Use a digital volt meter. 12.65 volts at the battery with the converter unplugged from ac power for 4 hours is fully charged. Anything below this and the battery is not fully charged or unable to hold charge.

Now, check power output at the battery with the converter plugged in. It should jump to somewhere between 13 volts and perhaps as high as 14 .5 volts. If the voltage doesn't jump up, check output fuses on the converter and ac power going to the converter plug. If all is ok you have a bad converter. If not, fix them. Converters are pretty robust. They can tolerate a lot but they can't handle wet conditions, dusty conditions, or AC spikes. Low voltage input can, over time, kill them too. Modern converters are very good compared to those manufactured even 5 years ago and they are much better for your batteries. The Intellipower and Iota converters both have a charging circuit thats 4 stage or 3 stage depending on model and your battery will probably be much happier and increase its life in a trailer by double.

Now, my understanding of the converters output, like that of the Intellipower 9255, is that while they are rated at max output of 55 amps, it's very unlikely it will ever deliver 55 amps unless your batteries are completely dead and every 12 volt light and other 12 volt appliance is on at once. Actually, the converter can be used in place of a battery (not recommended) and the output is equal to the current draw of the lights and other draws of whatever 12volt load is on. The larger the trailer and the more lights and gadgets that run on 12V determines the size of the converter. Big trailer + lots of stuff on = bigger converter. Smaller trailer less stuff 12 volts= smaller converter. The charge circuit of the the modern converter can be as little as 500 milliamps all the way up to 55 amps depending on battery condition and power draw. 55 amps is the upper limit the converter can output, not the battery charge circuit.

If you plan on putting in a larger converter you must also increase the wire size between the battery string and your converter so the wire does not get hot depending on current draw. Remember that more amps = larger wire size. Remember also that the negative side (chassis and white wires of the 12 volt circuit including the battery) is just as important as the positve side. Any bad connection between battery and chassis or any negative wire is just as problematic as the + side.

Older linear or transformer type converters are hard on batteries and don't do a great job of delivering stable, filtered 12volt DC power. They can cause voltage fluctuations and will boil your batteries dry if left on constantly. The modern converters are much better. They have a fan that ramps up depending on current draw to help cool them and their charge circuits are very good especially if you get a converter with a 3 or 4 stage charging circuit. Both Iota and Intellipower are very good units, have the charge wizard with 3 or 4 stage charging and they are widely available. I have a 40 foot 5er and many 12 volt appliances. My trailer came with an older 65 amp converter. I replaced it with an 80 amp Intellipower 9280 and added a #4 wire along side the #6 that was there on both the positive and negative side of the system.The 9280 has a charge wizard built in that allows for an intelligent charging without boiling the batteries. Welding wire is an excellent choice for this because of its durable outer jacket and small very fine strands of copper making the wire very flexible.

The rated output of a converter can be used by either battery charging or a power supply when plugged in depending on the need. If both are needed the unit will share the demand up to 55 amps. The only reason for a larger converter is if you plan on drawing over 55 amps at 12 volts at any given time. A larger converter will also be needed if you have a larger battery string. I currently have 6 6volt golf cart batteries and a 4000 watt inverter on my trailer so I can dry camp and still run my microwave and coffee maker, TV and DVD player. But small loads at 120 volts AC = huge loads on your battery string at 12 volts. To run my microwave not plugged into AC, I have measured a draw of 60 Amps out of the batteries to the inverter. That's why I have such a large converter to help with charging quickly 6 Trojan T55 batteries. I also keep my inverter leads as short as possible and run 4/0 wire from the battery string to the inverter.

Let us know what you find and what you plan to do,
-Paul R. Haller-

richardcoxid · 03-23-2009, 12:53 PM

Go to Trojan Etc. battery manufactures web site and look at their charging rate information, to small of converter will take forever to re-charge a discharged batt. To many charging AMPs will boil a batt dry.
If you do replace your converter it's GOOD information to purchase one of the 3 stage, "smart converters" there are more than one.

Jeff_in_The_Dalles · 03-24-2009, 02:12 PM

I see your rig is a 2005. It may have come with a multi stage converter, in which case I don't think it would be worth upgrading. Unless the batteries are flat dead it won't likely ever deliver full amperage to the batteries.

Regarding the lights dimming when several are on, 90% of the time I think that's due to the connection at the batteries.

They might look good from looking at them, but you have to take them apart to see that the contact area of the battery post is bright and clean. Also the end of the battery cable may be corroded under the insulation.

I'd start with getting some new cable terminals and cut a few inches off the battery cables and replace the terminals, and brush up the contact area on the posts.

I'd bet that improves your dim light situation. Even if it doesn't, I wouldn't consider it a waste of time/money, as it is a good preventative thing to do occasionally anyway...

woodburner · 03-24-2009, 03:58 PM

Thanks for all the great input folks! I appreciate it!

augoldminer · 06-17-2017, 08:51 PM

I have been thinking of dropping my convertor from 55 amp to 45 amp.

I have replaced all my light with 48 led pannels and got rid of the incandescent bulbs.
RV LED Light Conversion Kit 12-24 Volt 48 LED

Texastbird · 06-17-2017, 10:20 PM

I had my lights dimming and getting bright intermittently for awhile and then suddenly in February the converter quit entirely. I had been checking wires and connectors but couldn't trace down the problem. A new Progressive Dynamics converter fixed all my problems. Plus its supposed to have a smarter battery charger circuit. I went with the same as the original size for no good reason, since I am not an electrical engineer.