Improving converter performance, bigger wire size

tbrady · 03-19-2020, 11:27 AM

Hi All,

I have a 2017 Navion with an IOTA DLS-45 amp converter and 2 100ah LifeBlue lifepo4 batteries. Using the factory wiring I am only getting about 20amps of current to the batteries when charging. If I connect a direct 4ga line from the converter to the batteries I can charge them at 40ah (pretty much twice as fast). I'm assuming that the reason for the huge difference is the amount of resistance in such a long run for 8ga wire.

From the factory an 8ga wire is used from the converter to the ac/dc distribution center, and I assume the 8ga wire runs most of the way to the battery although I haven't figured this out yet..?

Has anyone tried increasing the wire size the converter uses? I've only started trying to trace the wire (the wiring diagrams aren't detailed enough for this) but it's difficult as it is bundled with about 50 other wires in a loom tighter than anything!

Any input greatly appreciated.

Winterbagoal · 03-19-2020, 11:41 AM

Have you tried adding one of these to adjust the DLS charger's output algorithm to lifepo4?
https://www.iotaengineering.com/IQ/#!/detail/IQ-LIFEPO
The wire gauge is probably the reason it's around 20A, but the charge control module might help that along, by maintaing a higher rate of charge for longer.

tbrady · 03-19-2020, 11:50 AM

Quote:

Originally Posted by Winterbagoal

Have you tried adding one of these to adjust the DLS charger's output algorithm to lifepo4?
https://www.iotaengineering.com/IQ/#!/detail/IQ-LIFEPO
The wire gauge is probably the reason it's around 20A, but the charge control module might help that along, by maintaing a higher rate of charge for longer.

Yes, I've tried that controller and it improves things slightly for a short amount of time. And actually, Larry at Starlight Solar (Lifeblue distributor) now recommends you not use that controller and instead use the dual-voltage plug instead. The Lifepo4 charging profile requires the battery to get to a very low SOC before bulk mode will kick in, or you have to reset the converter/controller to force it in to bulk mode.

Winterbagoal · 03-19-2020, 12:05 PM

Quote:

Originally Posted by tbrady

Yes, I've tried that controller and it improves things slightly for a short amount of time. And actually, Larry at Starlight Solar (Lifeblue distributor) now recommends you not use that controller and instead use the dual-voltage plug instead. The Lifepo4 charging profile requires the battery to get to a very low SOC before bulk mode will kick in, or you have to reset the converter/controller to force it in to bulk mode.

OK. I use a PD9245 converter/charger with my setup, and added their Charge Wizard Pendant to be able to boost the rate of charge just to finish the job, when I'm on shore. The solar and the alternator do a decent job at other times. 2 Relion RB100-LT 100Ah batteries. Our usage never gets them low enough that I worry about recharging to full.

powercat_ras · 03-19-2020, 12:11 PM

I had the same experience in my Winnebago Vista, where the 45A max output OEM converter is located about 12' away from the batteries and used 6 gauge wires. With my battery monitoring system, I could see the charger falling out of bulk charge mode at 70% rather than the preferred point of 80%.

When I replaced and relocated my inverter, I moved the Converter Charger to the former inverter location only about 4' from the batteries and reused the 2 gauge wires that had been feeding the inverter. I found that my batteries would charge to 80% in bulk mode after relocation with the shorter larger gauge wire runs.

DavidM · 03-19-2020, 01:22 PM

Li batteries need a fixed 14.6 voltage for maximum charging. The standard PD converter drops to a float voltage of about 13.6 volts so it does not charge Li batteries fully.

PD makes their 9100 series which has a 14.6 fixed voltage setting. Also upgrade the wire to #4 to minimize voltage drop which will also keep from charging the Li batteries fully.

David

Kayak73 · 03-19-2020, 03:00 PM

Great answer. I installed the PD9145ALV charger in the bay next to the coach door and the output to the inverter cables in place. Left the PD9245 in place with breaker off. The PD9145ALV charges the BB LFPs at 45 amps fast and the correct voltage, made for the lithium batteries. My generator runs are really short now when boondocked. I don't really worry about parking in the shade and solar now.

powercat_ras · 03-19-2020, 03:23 PM

Sorry, I did not read the first post carefully. Yes, you have to replace the Winnebago OEM converter/charger, designed only for use with Lead-acid batteries, with one designed for LiFe04 if you change from Lead-acid to LiFe04 batteries. You may have problems with the OEM battery isolation manager, if your Winnebago has one, not fully charging the LiFe04 batteries as well.

My post regarding bigger wire and moving closer to batteries only applies if you have Lead-acid batteries.

tbrady · 03-19-2020, 03:36 PM

Quote:

Originally Posted by powercat_ras

Sorry, I did not read the first post carefully. Yes, you have to replace the Winnebago OEM converter/charger, designed only for use with Lead-acid batteries, with one designed for LiFe04 if you change from Lead-acid to LiFe04 batteries. You may have problems with the OEM battery isolation manager, if your Winnebago has one, not fully charging the LiFe04 batteries as well.

My post regarding bigger wire and moving closer to batteries only applies if you have Lead-acid batteries.

Hi powercat, yes I've already replaced the converter with one better suited for lifepo4. And your comment does apply to lithium as well. In my current setup I have the 45amp converter putting out a constant 14.4v over an 8ga wire that runs about 25ft. Max current is about 20amps in. I tested using a 4ga wire that was around 15ft long and the current went up to 40 amps.

So... at the moment I'm trying to figure out exactly how the wiring runs from the ac/dc distribution panel to the battery. It looks like it may run up under the passenger side seat and tie in somewhere there? Once I figure out the current wiring I plan to change the 8ga wire over to 4ga.

al1florida · 03-20-2020, 07:17 AM

tbrady. Your profile shows you are in the Northwest. I thought T. Brady was in New England, but is moving to Tampa Bay.

powercat_ras · 03-20-2020, 08:38 AM

Tbrady, you can go to winnebagoind.com and get some electrical diagrams for your unit. You can at least see how the 12 volt and 120 volt wiring is physically run in the unit. They stopped posting the full wiring diagrams in about 2014, but what is there will help you some.

tbrady · 03-20-2020, 10:03 AM

Quote:

Originally Posted by powercat_ras

Tbrady, you can go to winnebagoind.com and get some electrical diagrams for your unit. You can at least see how the 12 volt and 120 volt wiring is physically run in the unit. They stopped posting the full wiring diagrams in about 2014, but what is there will help you some.

Thanks Randy, they did get me pointed in the right direction. I figured it out yesterday between those and a multimeter. It's basically just a wire that runs from the ac/dc distribution center to the "panel" under the passenger seat. I'm pulling the wire today, it's a real pain in the butt since I had to pull up all the floorboard stuff in the cab to get the wire through.

What's crazy is that from the panel under the passenger seat to the battery on/off relay they ran 4ga wire. I figure they saved about $5 by running 8ga instead of 4ga the rest of the way.

Anyway, the testing I did yesterday shows a steady 40amps in to the batteries compared to the 20 I was getting before. Since we boondock 95% of this time it really cuts down on how long we need to run the genny.

JoeC · 03-25-2020, 05:07 PM

This post is a fine example of what can and will happen when making changes to your electrical system. ALL of the individual pieces and parts are engineered as a system and optimized around price/performance characteristics. If you change ONE thing, you will likely have to reengineer part or all of your system, depending on what was changed. Most of us are not trained to foresee what will happen when making changes, even "minor" ones. This is why I always preach to get qualified technical help to review any electrical system change. The operative word here is "qualified", subject to different interpretation from place to place.

In short, do as much research as you can way in advance, ask questions about your prospective change(s), review your change(s) with an experienced individual and then develop an implementation plan, possibly a multi-phase plan, then order and execute.

Happy camping to all, after we recover from this pandemic.

Retfed · 04-04-2020, 02:15 PM

I have a 2007 Winnebago View and had issues similar to yours after installing a PD9245 about four years ago. My 8 gauge wiring was the problem but I didn't want to replace it. I solved the problem by adding a 6 gauge wire between the converter '''Batt Pos''' lug and the generator positive post (about 8 ft of wire needed). This shorter charging route using larger wire plus the original circuit improved charging voltage in all phases of the PD converter. I added a circuit breaker in the 6 gauge wire near the generator positive post to provide protection for the power from the converter to the chassis electrical box.

**creativepart** · 04-04-2020, 03:03 PM

Question? If the two wires are different lengths and different gauge won’t they be receiving unbalanced current flow that would make the longer, lighter wire just about useless, not helping the overall situation?

powercat_ras · 04-04-2020, 04:04 PM

No the smaller wire in parallel with the bigger wire lowers the resistance vs. 1 wire alone. The lower the resistance the less voltage drop there will be. Helps, can't say exactly how much though.

DavidM · 04-04-2020, 04:17 PM

Quote:

Originally Posted by powercat_ras

No the smaller wire in parallel with the bigger wire lowers the resistance vs. 1 wire alone. The lower the resistance the less voltage drop there will be. Helps, can't say exactly how much though.

David