Power Converter Upgrade

[mjlaupp]

Originally Posted by mcgyver210

Did it fit existing location without modification?

Other than the wiring mods, the fit is perfect.

What was cost of this upgrade?

Model PD4645V - 45amp
Camping World List: $266.66
Presidents Club Price: $239.99
Shipping/Handling: $7.00
Sales Tax, Louisiana: $9.60
Total: $256.59

Additional materials: $?.?? - I had these on hand. (Sources: Radio Shack or auto parts store)

How about some pics.

I am importing them to my computer, will publish as soon as I get them sized.

Mike

[mjlaupp]

Originally Posted by harveyrv

Be sure to read each post as I progressed through the installation of this converter. It's a great converter but to get the total benefit of it, it needs to be mounted very close to the batteries or very large (battery cable type) wires must be installed between the converter and the battery.

This install was in a 3326King. This is one of the front slide out models with the batteries (2 6v golf cart batteries) located in the rear storage area. The distance from the charger to the batteries is no more than in your front converter installation. I'll have to evaluate this installation over the next few months and will provide updates as needed. I chose this upgrade because it was supposed to be plug and play. I had no charging problems with the 7345 upgrade in my 2003 2720SL. It was a 45 amp charger and had the same distance to the 2 golf cart batteries.

Mike

[Wavery]

Originally Posted by mjlaupp

This install was in a 3326King. This is one of the front slide out models with the batteries (2 6v golf cart batteries) located in the rear storage area. The distance from the charger to the batteries is no more than in your front converter installation. I'll have to evaluate this installation over the next few months and will provide updates as needed. I chose this upgrade because it was supposed to be plug and play. I had no charging problems with the 7345 upgrade in my 2003 2720SL. It was a 45 amp charger and had the same distance to the 2 golf cart batteries.

Mike

AHHHHH!! I didn't realize that you had a slide.......that changes everything...

Assuming the batteries are under 10' from the converter, you should get acceptable voltage. The problem is with those of us that have that long distance between the batteries and converter........good thing lots of people read these posts.....maybe my experience with this upgrade will help someone..

[mjlaupp]

Pictures added.

[mcgyver210]

Good Job nice pics.

Thanks for posting them I think pics are GREAT for showing mods

[Wavery]

Originally Posted by mjlaupp

Pictures added.

Great job.........looks like original equipment. Should work well.

Thanks for the pics......

[Bill]

Originally Posted by harveyrv

Do yourself a favor. Run the batteries down then plug in the converter. Immediately check the voltage and amperage at the converter, then check the voltage and amperage at the batteries. I think that you may be surprised at what you find.

The travel from the converter to the batteries and back is about ~40'. Because of the wire size used, the voltage drop is great. Even if your converter is putting out 14.4V, the batteries may only see ~13.4V.

Wayne, I'm going to disagree with you a little bit here. I think you have lost track of the fact that the voltage drop is proportional to the amount of current that is flowing in the wires. Yes, if the initial charge rate is 40 amps, then the initial voltage drop will be large, just as you say. But after the first couple minutes of battery charging, the charge current decreases, and so the voltage drop decreases. In other words, the voltage at the battery will rise (since there is less drop), and will get very close to the charger voltage (14.4V in your example). It will take a couple minutes longer to charge the batteries, but not much. They WILL get charged.

Maintenance charge is even worse. When the converter is putting out a 13.8V maintenance charge, the batteries may only see about 12.9V (due to wire resistance). That is not enough to keep the battery fully charged.

A maintenance charge, by definition, is a very small current - perhaps 1 or 2 amps at most. At this low level, there is almost no voltage drop, so the battery sees the full charger voltage.

Most people feel that if they put a bigger converter on their camper, it will solve this issue. Not true. It doesn't matter if you have a 15A converter or an 80A converter. It's all about the voltage that's able to make it to the batteries. Amperage has nothing to do with it.

This is true. The rating of the converter represents the maximum that the charger CAN provide, but doesn't guarantee it WILL provide it. As you say, the actual current provided depends strongly on the state of charge of the batteries, and to a lesser extent on the resistance of the charge wires.

This is why the converter should not be used as a primary source for charging and maintaining the batteries (unless the converter is within a few feet of the batteries and/or the appropriate wire size is used).

Here is where I think you have reached the wrong conclusion. As noted above, the converter is perfectly good for charging batteries, although at very high charge rate it might take a couple minutes longer. In fact, a simple charger such as the old Magnetek/Parallax units will charge your batteries - and then happily continue to charge them until it overcharges them.

A "Smart" battery charger hooked directly to the battery bank maintains the batteries better than the best converter that you can buy if the converter is mounted 20' away and only uses 10g wire to handle the current.

A smart charger will not overcharge the batteries - that is its primary advantage, and it is a big one. But it does not require short wire runs to perform its "smart" function.

That is why I re-mounted my new converter right next to my batteries. I get the full voltage and I get 45A (at full charge) at the batteries.

As you say, the maximum initial charge rate will be obtained with short heavy wires. But I bet that if you had checked the charge rate after five minutes, you would find that it had dropped from 45 amps to 10 amps or less. That means that the initial voltage drop (about 1 volt, as you noted) was reduced to less than a quarter of a volt. In your opening sentence, you said to hook up the charger and then immediately measure the charge current. But the "immediate" part of the technique is what leads you to a wrong conclusion, since you are measuring the short-term transient current, not the steady long term current that actually does the bulk of the charging. It is more meaningful to hook up the charger, wait five minutes, and then measure the charge rate.

Bill

[mjlaupp]

Bill,
I was thinking the same thing about the wire/volt/amp thing. However, I was having soooo much phun uploading the pictures through the Hughes Net system, that I could not get a response together before you did.
Mike

[Wavery]

Originally Posted by Bill

Wayne, I'm going to disagree with you a little bit here. I think you have lost track of the fact that the voltage drop is proportional to the amount of current that is flowing in the wires. Yes, if the initial charge rate is 40 amps, then the initial voltage drop will be large, just as you say. But after the first couple minutes of battery charging, the charge current decreases, and so the voltage drop decreases. In other words, the voltage at the battery will rise (since there is less drop), and will get very close to the charger voltage (14.4V in your example). It will take a couple minutes longer to charge the batteries, but not much. They WILL get charged.

A maintenance charge, by definition, is a very small current - perhaps 1 or 2 amps at most. At this low level, there is almost no voltage drop, so the battery sees the full charger voltage.

This is true. The rating of the converter represents the maximum that the charger CAN provide, but doesn't guarantee it WILL provide it. As you say, the actual current provided depends strongly on the state of charge of the batteries, and to a lesser extent on the resistance of the charge wires.

Here is where I think you have reached the wrong conclusion. As noted above, the converter is perfectly good for charging batteries, although at very high charge rate it might take a couple minutes longer. In fact, a simple charger such as the old Magnetek/Parallax units will charge your batteries - and then happily continue to charge them until it overcharges them.

A smart charger will not overcharge the batteries - that is its primary advantage, and it is a big one. But it does not require short wire runs to perform its "smart" function.

As you say, the maximum initial charge rate will be obtained with short heavy wires. But I bet that if you had checked the charge rate after five minutes, you would find that it had dropped from 45 amps to 10 amps or less. That means that the initial voltage drop (about 1 volt, as you noted) was reduced to less than a quarter of a volt. In your opening sentence, you said to hook up the charger and then immediately measure the charge current. But the "immediate" part of the technique is what leads you to a wrong conclusion, since you are measuring the short-term transient current, not the steady long term current that actually does the bulk of the charging. It is more meaningful to hook up the charger, wait five minutes, and then measure the charge rate.

Bill

Point taken.........you're right about that.

My initial charge is 47.2A and it naturally drops rather quickly or it would generate too much heat. I will have to time it next time. I did notice that after about 30 minutes my meter read 18A. Don't know how long it stayed there (I have 2 - 27 series batteries).

In the case of dry camping, that initial charge @ max output is important because I am using a generator for charging. However, for home maintenance, you are correct. The lower the amps flowing through a smaller wire the higher the voltage that can pass through. At the low charge rate for maintenance 13.8V should not be an issue. Thanks for clarifying that.

I want to thank each of you that have posted this information. It is invaluable to gain the perspective of all your knowledge and save the rest of us significant amounts of time, effort, energy and money.

Much appreciated.

Virgil