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Old 11-22-2009, 08:33 AM   #1
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Converter swap....what wires where??

I clipped the wires going into the old Univolt and removed it. I'm replacing it with a new Iota DLS 55 purchased from BestConverter. I'm planning to bypass the two house batteries altogether since my '89 Excella is always connected to shore power, as my Airstream is my permanent home office. The wires that were running from the distribution panel into the Univolt were the 6-gauge bare copper to the chassis bonding lug and a 6-gauge white insulated stranded wire. I assume the white is my negative since it is coming off the bottom of the three connectors in the bottom left of the panel named "load grounds" in my owner's manual schematic, along with the bare copper ground.

The other wire that was running from the panel to the Univolt is the blue 12-gauge wire that can be seen in the photo running off the bottom right thermal breaker. I'm concerned that it is a much wimpier wire than the white ground wire. I'm wondering if I can disregard the blue wire (as in eliminate) and run the big red battery cable (see photo) from it's current location to the positive terminal lug instead. The red battery cable was running to the battery kill switch before.

Thanks in advance for any/all advice. I'm so NOT intelligent about all matters electrical. CarpetBob
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Old 11-22-2009, 10:25 AM   #2
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CarpetBob,

It doesn't look right to have a #12 wire as the line from the Univolt. It might be something done by a previous owner.

Does the picture differ from what is shown in your owners manual schematic?
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Old 11-22-2009, 11:39 AM   #3
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Bypassing the batteries can be a bad idea for some converters, since the battery charging current is a small load that helps the converter regulate its output voltage. The modern converters are generally able to do a good job of regulation without any load, so with your new converter you're probably fine.

That #6 battery cable is not needed, now or ever. Like, where is the 400 horsepower engine you are starting?http://www.airforums.com/forums/770380-post373.html

You need at least a pair of #10 wires, maybe #8 at th absolute max, from the converter to your distribution "panel." Replace the blue wire, but continue to run your converter (+) positive output to that thermal fuse. If you have a heavy ground wire already, you only have to deal with the blue wire.

If you leave the red battery wire in place and connected to the batteries, the batteries are still in the system. They have not been "bypassed" unless you disconnect them.

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Old 11-22-2009, 12:24 PM   #4
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Zep,

I bought the Iota DLS 55 on Randy's suggestion at Best Converters because it can be effectively operated with or without the batteries connected to the system. Yes, the batteries will be disconnected from the system.......thanks for not assuming I would have that under control (I might not!). I will replace the wimpy blue wire with a heavier gauge and disconnect the big red battery cable. The existing wire from the ground block is plenty hefty. Sounds like I'm good to go.....thanks to your advice. Thanks so much! "Verbalizing" it helps me to get an intellectual grip on it.

CarpetBob


ps-I'm guessing that the blue wire is a homemade add-on since it's blue coming off the thermal fuse and a different color, but equally wimpy, coming out from underneath the wall!!
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Old 11-22-2009, 12:29 PM   #5
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The blue wire appears to be isolated from the rest of the 12 volt bus. Could it be for the lower on light only. In the 70s that was a seprate circut out of the univolt and isolated from the battery. That might explain the smaller wires.
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Old 11-22-2009, 01:02 PM   #6
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AZ,

It is separated from the rest, all the other thermal breakers are connected with a network of copper bars. Is that going to be a problem using it as the take-off point for my positive connection to the converter? Thanks, Bob
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Old 11-22-2009, 02:09 PM   #7
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Not a problem to leave the breaker in the circuit.

The reason for the copper bars is that they were intended to carry max battery current (could be 400+ amps if there was a dead short somewhere) to fan out to each of the circuits. For any normal situation, the copper straps are way overkill. Just leave them.

The single breaker on the blue wire (for the converter), only had to carry the max current of the converter (25-60 amps, depending on the converter). It is still a good idea to have a breaker in the converter circuit, but your new converter probably has fuses, so the breaker is unnecessary. I'd leave it, simply because it's a nice visual clue as to which wire is the converter wire.

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Old 11-22-2009, 02:20 PM   #8
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Zep,
I am confused by the setup in the picture. What is the single breaker for? I can see the others all tied together with the bus bar and I figures they were all the branch circuits to the trailer. Not knowing what the single breaker was for, I thought it might be for the Power Light.

This panel is very different then the ones from the 70's.
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Old 11-22-2009, 07:21 PM   #9
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That solo breaker is like the 40-amp thermal breaker in the tow vehicle charge line. It's just a way to protect the converter from the batteries, or in the old days, to protect it from an overload, like a short of the copper buss bars to ground. Any other short would open up its respective circuit's breaker. The old converters didn't have auto-shutdown to protect themselves.

I'm a big fan of putting a 40-amp fuse in each battery circuit, for two reasons. First, you can make a quick fire if you short a battery to ground and second, it's nice to be able to isolate a battery just by pulling a fuse. Heck of a lot cheaper than a battery disconnect switch. Lots of members think you need to draw more than 40 amps from the batteries, but it's just not so (unless you the kind of zombie who thinks a 1000 Watt inverter is cool). You should never draw more than battery capacity divided by 2 as the max current, and you should stay far from that if you can. For example, if you have a 105 amp-hour battery, you should limit your total current to less than 52 amps at all times.

And, while I'm at it, you should never ever draw a lead-acid battery down below 20% of its total capacity. So if you have the same 105 amp-hour battery, it's really only good for 83 amp-hours, or you'll damage it for sure.

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Old 11-25-2009, 07:47 AM   #10
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AZ and Zep,

Thanks again for your help. According to the schematic on the inside of the distribution panel door, that separate breaker on the lower right is indeed the "power on". When I connected the new converter positive to it, nothing happened. However, when I moved the positive up onto one of the interconnected breakers, reggae music started pouring out of my stereo system. I love when that happens!

Several months ago I had installed a new CD changer/receiver to replace the original "car" stereo. But I was bummed because every time I turned more lights on, the stereo would cycle off and then restart a few seconds later. However, now that I have the new converter installed the stereo works flawlessly. House lights burn brighter, the doorbell rings louder, and the converter is hum-less. Less than $200 to make all this good news.

BTW, I used #8 wire to make my connections to the converter because the existing ground is #8, and because that gauge wire fit well into the connections on the converter.

CarpetBob
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Old 11-25-2009, 09:14 AM   #11
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Cable size

I too was sold on the IOTA converter by Best Converter. The picture attached shows the current system...inverter left, Univolt center and battery box right. Other batteries out of sight left and right. System is set for Solar Panels. Do I really need this size welding cable ? On the IOTA I plan on using #10 NEG and POS connecting cable. Is that O.K.

By the way, note that the installation has bypassed the circuit protection in the 12v panel. I'm confused (normal condition) because I read what Zep says....to fuse the batteries.... and then I got from Greg at Inland that they bypass those circuit protectors on purpose. Any ideas along this line?

On the all new electrical system I am building up for the 47 I plan on doing the same thing....no humongous battery cables....no battery fusing.... Again, is that going to be OK?
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Old 11-25-2009, 03:29 PM   #12
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Quote:
Originally Posted by carpetbob View Post
AZ and Zep,

... According to the schematic on the inside of the distribution panel door, that separate breaker on the lower right is indeed the "power on". When I connected the new converter positive to it, nothing happened. However, when I moved the positive up onto one of the interconnected breakers, reggae music started pouring out of my stereo system. ...
Either that breaker is broken and is not making a connection, or it's a very low current breaker, too low to power up the bus. Either way, you took the right step to check it out and make it work. I assume with some confidence that your converter has an output fuse (my Intellipower does, on both the (+) and (-) leads), so you don't really need an additional breaker.

Zep
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Old 11-25-2009, 03:35 PM   #13
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Quote:
Originally Posted by Melody Ranch View Post
...By the way, note that the installation has bypassed the circuit protection in the 12v panel. I'm confused (normal condition) because I read what Zep says....to fuse the batteries.... and then I got from Greg at Inland that they bypass those circuit protectors on purpose. Any ideas along this line?
...
First, no humongous cables: that's OK. The debate is whether you need #8 or if #10 is good enough. Nothing is good enough if you have an accident and ground the battery. If you hold the max currents to the recommended 40 or so amps (and mostly less than that), then #10 is safe. But for longer cable runs, #8 would be better, but it's a PITA to work with.

Second, bypassing the battery protection: If everything is properly fused, meaning all the circuits, then any accidental short on a circuit will blow that circuit's fuse--battery and wires are protected. I am really a fan of NOT having a battery fuse. That being said, I've been in situations where I've disconnected the battery wire from the fuse block without disconnecting it from the battery first. In this case you are holding a potential arc welder in your hand. If it's not fused, you better be extremely careful to keep it under control and not touch the shell with it. Having that battery cable fuse, even though it's aggravating, will protect you when you're doing electrical maintenance and suddenly become stupid. So I put them in. Ugh.

Zep
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