Has anybody modified their charging system?

[BrooklynBay]

This is the 2 gauge inverter cable kit: 6 Ft. Inverter Cable Set - #2 AWG. I needed an 8 foot cable but this was the only 2 gauge wiring kit which was available.

 

[gmanpaint]

Pretty much the same.

If you go to renogy.com and look up the DC to DC units, they should have wiring manuals, you can download and view the actual layouts.

I have those same cables, only I have the 3ft versions for the inverter. Pretty stout cables.

 

[CDW6212R]

The 300 amp alternator came in the mail today. I want to upgrade the main cable on the alternator to 4 gauge, and install this alternator. I hope that it will solve the low current issue to keep the battery charged while using the inverter.

On the alternator power cable, don't cut out the old one. Either tape the ends covered, or leave it in place and add a new cable to both ends. I'm not sure what the electrical effects can be with much higher currents, but I would add a cable capable of handling the total load. The current splits by the path of least resistance, so it shouldn't over power the OEM cable(unless the large one is broken etc).

I added an 8ga cable to mine, when I upgraded the alternator to 170, and then 200 amps. I didn't change the main fuse at the PDB, you need to increase/alter that circuit protection given that 300 amp alternator.

 

[shucker1]

If read this post twice and see no mention of "Inrush" current when the A\C unit kicks on.

Does the inverted have enough head room left over to compensate for that?

It also may be a good idea to add fuses somewhere so you don't end up with a "Roadside Weenie Roast".

 

[BrooklynBay]

The inverter has a 2,500 - 5,000 watt rating with built in fuses.

 

[BrooklynBay]

I have an update. The alternator with the 4 gauge cable is installed. I was able to run the A/C at idle but the voltage was low (about 12.5 volts when cold started). It was able to idle for 15 or 20 minutes until the low voltage alarm in the inverter went off. It was around 11.9 volts. I would expect a 300 amp unit to maintain more output under a load. I didn't test drive it yet.

I'm using the 4 gauge wire with the original thin cable.

 

[gmanpaint]

I was afraid that was going to happen. The AC compressor is using power faster than the battery is charging.

When an RV is running AC on the road, it uses the engine like a generator. The AC is not drawing from the battery, but rather the converter. Portable gas generator's are also inverters, and supply the 120v source directly to the output, with no battery involved.

I hate to say it, but I think your going to have to do something along the RV style wiring. Look and see if you have any RV salvage yards near you. You can get the converter units dirt cheap from them. Research the units that would work for your application.

If you want to spend the $$ on new units, there are some made with mounting boxes, made for camping/ horse trailers.

 

[BrooklynBay]

I was watching the voltmeter after I shut off the A/C. It looks like this unit recharges the battery faster. This set up should work if I keep the A/C on a high setting like 85 or 90 degrees. It will give the battery time to charge when the fan is running without the compressor.

 

[CDW6212R]

The idle current of an alternator is much different than the rated max. The typical aftermarket units I've noticed similar to our 90's Fords, have been in the 100amp range, at idle. What they make at 700rpm will differ from at 1000rpm, and higher. That's part of why I was hopeful the 3G models would be better, more aftermarket support.

 

[BrooklynBay]

This alternator came with a 48mm pulley. The stock pulley is 58mm. This should increase the charge while idling by a small percentage. I swapped a different pulley onto the automatic belt tensioner which was a little larger. Spare parts come in handy.

 

[BrooklynBay]

Here's a side by side comparison of both alternators:

 

[BrooklynBay]

I wasn't planning on making such a big project out of this, and wanted to use what I already have but things don't always go the way you want. This portable air conditioner looks like it requires less power to run compared to what I have now, retains memory of the last setting before the power went out, and comes with a remote control: Danby 6000 BTU (3000 SACC) Portable Air Conditioner with Dehumidifier in Black-DPA060B7BDB - The Home Depot

 

[BrooklynBay]

I have an update. The Danby 6,000 BTU A/C appears to work fine with my set up. I ordered one from a crook on EBay, but he never shipped it or responded to emails until I opened a case to get a refund. I ordered a second one from Home Depot after I got a refund from EBay. It was cheaper but took two weeks to get. They took their time mailing it from Arizona (4 days until they put it in the mail), then there was a holiday so UPS put it in a warehouse for another 4 days.

Here are my test results:

The first test was to let the van idle with the A/C on. The voltage was stable for almost a half an hour until it gradually decreased. The internal low voltage alarm in the inverter went off. It ran for a few more minutes until it shut down.

The second test was today. I had it on while I was driving, but I only did a few short runs so the A/C wasn't on for that long. The voltage on the dashboard was pretty stable except for a few intermittent fluctuations, but it pretty much remained in the correct range. The inverter maintained the correct voltage as well as the alternator, so the A/C performed as it should. I haven't tested it for long driving but from what I could tell, the charging system is able to keep up with it for basic runs around town. I would like to test it for a 30 to 45 minute run at some point.

The A/C has a built in time delay, so the fan only runs without the compressor for a few minutes when it starts. The compressor kicks in after this time delay. This gives the charging system a few minutes to charge the battery when I first start driving.

 

[CDW6212R]

So you are still satisfied with that alternator, great.

I wanted to replace one of my 4G's in my new 98 truck, bearing noise. I took my older aftermarket 4G in to rebuild(DB Electronics), and the shop said it was toast, fused the board etc. So they sold me instead an OEM rebuilt, good price so I got it.

They also confirmed the 4G still has no useful upgrades, and the 3g still has excellent possibilities. So the 3G is the one to go with if you need anything beyond the stock 130/140 amp levels. I'll have to look into what might be possible to fit a 3G into the 4G space(one bolt hole is off(unusable) on the bracket).

 

[BrooklynBay]

Check the link to the seller on EBay on the previous page. He might have something for you.

 

[CDW6212R]

Check the link to the seller on EBay on the previous page. He might have something for you.

I did check out that listing, and I put it in my watched list.