Wire gauge for Change from 12v to 6v Batteries in 2013 Hawk

[Bwht4x4]

I'm replacing my original FWC-supplied Exide dual 12 volt group 24 AGM batteries that came with our camper in 2013 with two Lifeline 6 volt AGM batteries (220 ah). Is there a need to upgrade the original wiring in the battery compartment to a larger gauge? I believe it is currently 6 gauge, which from what I can tell from my research is more than adequate. It doesn't seem like up-sizing the wire is needed based on the max amp draw we could place on the system. If I turned everything on I have in my camper I don't think I could get more than a 15 amp draw. I don't have or use an inverter ever.

Thoughts?

 

[Stokeme]

With my basic understanding, I would say no, leave it alone. My guess would be the wire is 8, though, not 6. Also, just doing the box would have minimal effect. Re-doing the entire line from roof to box, with heavier gauge, would offer the greater benefit. Nightmare scenario.
It looks like your parallel cables are heavier? Just to throw this out there, I used these 4 gauge pre-made cables to interconnect my batteries. If you have 6, that should be plenty good, as that interconnect run is very short.
https://www.amazon.com/gp/product/B071DYLGST/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

My 2 cents, plenty of guys on this Forum have better knowledge ... looks nice!

 

[Bwht4x4]

Thanks for the info Stokeme. The pict I provided is the old 12 volt setup. Like you mentioned, I was thinking of upsizing the battery interconnect cable to a 10 inch to 12 inch section of 4 or 2 gauge, but I'm not sure if it's even needed. I'm going to go out right now and see if I can determine what gauge the existing wires are.

 

[Stokeme]

Sorry, did not notice you were going to 6V. So, I assume you will be running them in series to obtain 12 V. Everything else mentioned remains the same. FWC may use 10 gauge, vaguely recall not even 8 ... would still recommend to leave as is ... use heaviest gauge possible that works with your controller/battery connect & one gauge heavier with your battery connect.

 

[Bwht4x4]

Just went and took a look at what the wire gauge is. It looks like nearly all of it is 8 gauge, except for the black wire that goes from the battery in the upper part of the photo to the shunt in the lower right of the photo is 6 gauge. I think I'm going to get the new batteries set in place and then have a custom battery interconnect cable made out of something much thicker. My buddy has an AM Solar kit with the same batteries and they used 4/0 cable for the battery interconnect cable, which is huge!!!

 

[Vic Harder]

I can't see your picture for some reason.... that said, in principle, just a battery arrangement change won't necessitate a thicker wire gauge.

Since you do need at least one new wire to hook them up in series, I'd beef up that one wire to as thick as you like... Anything over 4 g would be overkill, never mind 4/0 wow.

FWIW, I'm using 2g in my setup (in the battery box and between the 3000w inverter and the batteries), with 4g from truck to camper. Important to note that my batteries are in parallel, not series!

 

[Jack]

Unless you are going to attach an inverter (12 VDC to 120 VAC), 6 gauge or even 8 gauge is fine - but see note below on charging.

The two main criteria for picking wire gauge are current capacity and voltage drop.

The maximum current through the FWC fuse block is 30 A, so 10 gauge is fine. If you are running an inverter directly off of the batteries, you need a wire gauge to handle the current draw by the inverter. A 700 W inverter can draw up to about 55 A, so you would need 6 gauge wire - and this would be true for the cable between the two 6 V batteries. All copper wires have some resistance and so they act a very tiny bit like a heating element. As long as you don't run more current that the wire is rated, you can't feel the heat, A thicker wire (lower gauge number), say 8 gauge to 6 gauge, for a 10 ft length, will save you less than 1 W.

Voltage drop is important for battery charging and battery isolation. Because of the wire resistance, the voltage at the end of the wire is less than the voltage at the source. A thicker wire has less resistance so the voltage drop is less. This is why solar charge controllers should be close to the battery (shorter distance, less resistance) and/or use thicker wire (less resistance) so the charge voltage is what the battery needs. The exception is for solar charge controllers that can sense the voltage at the battery (Victron) - they source a higher voltage such that the voltage at the battery is what is needed.

The battery separator is the other voltage sensitive device in the FWC. The Sure Power 1314A needs to see 13.5 V to believe that the truck alternator is producing power and therefore connect it to the FWC battery. FWC fuses that line to 30 A. If you have 20 feet of wire (10 ft each way) at 30 A, that's a 0.6 V voltage drop. The alternator has to source 14.1 V for the 1314 A to see 13.5 V connect the the alternator to the FWC battery over the FWC 10 gauge wire. 8 gauge wire would have a voltage drop of about 0.35 V

 

[Jack]

Unless you are going to attach an inverter (12 VDC to 120 VAC), 6 gauge or even 8 gauge is fine - but see note below on charging.

The two main criteria for picking wire gauge are current capacity and voltage drop.

The maximum current through the FWC fuse block is 30 A, so 10 gauge is fine. If you are running an inverter directly off of the batteries, you need a wire gauge to handle the current draw by the inverter. A 700 W inverter can draw up to about 55 A, so you would need 6 gauge wire - and this would be true for the cable between the two 6 V batteries. All copper wires have some resistance and so they act a very tiny bit like a heating element. As long as you don't run more current that the wire is rated, you can't feel the heat, A thicker wire (lower gauge number), say 8 gauge to 6 gauge, for a 10 ft length, will save you less than 1 W.

Voltage drop is important for battery charging and battery isolation. Because of the wire resistance, the voltage at the end of the wire is less than the voltage at the source. A thicker wire has less resistance so the voltage drop is less. This is why solar charge controllers should be close to the battery (shorter distance, less resistance) and/or use thicker wire (less resistance) so the charge voltage is what the battery needs. The exception is for solar charge controllers that can sense the voltage at the battery (Victron) - they source a higher voltage such that the voltage at the battery is what is needed.

The battery separator is the other voltage sensitive device in the FWC. The Sure Power 1314A needs to see 13.5 V to believe that the truck alternator is producing power and therefore connect it to the FWC battery. FWC fuses that line to 30 A. If you have 20 feet of wire (10 ft each way) at 30 A, that's a 0.6 V voltage drop. The alternator has to source 14.1 V for the 1314 A to see 13.5 V connect the the alternator to the FWC battery over the FWC 10 gauge wire. 8 gauge wire would have a voltage drop of about 0.35 V

 

[Vic Harder]

As Jack points out above, the Sure Power 1314A senses battery voltage. Let's say it does sense 14v at the truck alternator... it says "Yeah, I can connect the alternator to the camper battery". And it does so. You hear a "CLICK".

Current starts to flow over the 10g wire between the alternator and the camper battery. A lot of current, say 30A. That heats the wire up, and power (voltage) is lost trying to move that much juice over the small wire. Such that, as Jack says... there is a .6V drop. 14v 0.6v = 13.4 volts. NOT enough for the 1314A to believe that the alternator is putting out enough voltage to connect the two systems (even though the voltage has NOT changed at the alternator!). You hear another "CLICK"

This repeats as you are driving your truck, blissfully unaware that charging is not happening, except for those short periods between clicks.

Thicker wire can help, as it could keep the voltage from dropping too much. But that again assumes an alternator that puts out 14v or so. Newer smart alternators won't do that as they are optimized for 12v to keep all the infotainment systems happy, and to improve fuel economy.

So you can see why the stock system with the 1314s is not going to work.

A better separator is with thick wires is good and works if you need bi-directional charging. A DC-DC charger is likely better for most folks with newer trucks.

 

[Bwht4x4]

After talking with Lifeline and Iota today I'm having concerns the stock Iota DLS-30 will do a good job of charging my new 6 volt AGMs. The charge profile of the Iota converter/charger is higher at both bulk and float according to the recommendations by Lifeline. Even with any of the various IQ Smart Charging Modules the float of 13.6 volts is higher than what Lifeline recommends. Iota did explain to me how to adjust the voltage of the DLS-30, but I'm not sure I want to open the case and attempt it.

The DLS-30 worked great on my stock 7 year old group 24 AGM batteries, so I may just leave it as is and install the new batteries.

 

[Vic Harder]

After talking with Lifeline and Iota today I'm having concerns the stock Iota DLS-30 will do a good job of charging my new 6 volt AGMs. The charge profile of the Iota converter/charger is higher at both bulk and float according to the recommendations by Lifeline. Even with any of the various IQ Smart Charging Modules the float of 13.6 volts is higher than what Lifeline recommends. Iota did explain to me how to adjust the voltage of the DLS-30, but I'm not sure I want to open the case and attempt it.

The DLS-30 worked great on my stock 7 year old group 24 AGM batteries, so I may just leave it as is and install the new batteries.

what are the recommendations and the IOTA settings?

 

[Bwht4x4]

Here are the various details I acquired today:

Lifeline AGM Battery Charging Recommendation:
Bulk/Absorb - 14.2 - 14.4
Float - 13.2 - 13.4

Iota DLS Converter/Charger with three different Smart Charger Modules

IQ SMART-CHARGER - IQ4
Bulk - 14.8
Absorb - 14.2
Float - 13.6

IQ SMART-CHARGER - Gel
Bulk - 14.23
Absorb - none
Float - 13.6

IQ SMART-CHARGER - AGM
Bulk - 14.7
Absorb - none
Float - 13.6


The tech at Lifeline was shocked I got 7 years out of my original AGMs running the Iota DLS-30 with the IQ4 module. I can't explain it either, but it worked!! I confirmed today using my Bogart Trimetric Battery Monitor and my Klein True RMS multimeter that float voltage with my current setup is 13.60 volts.

 

[Vic Harder]

Will lifeline not honor their warranty if using the iota's parameters? That would be a good reason to get a more programmable charger.

 

[Bwht4x4]

I didn't ask about honoring the warranty. From my experience if you identify a problem for a manufacturer they'll almost always say NO, they will not honor the warranty.

I think I may try to remove the cover of the Iota DLS and see if I can tweak the voltage down 0.4 volts, which would put the charging profile in the sweet spot for the Lifeline batteries.

 

[Vic Harder]

I didn't ask about honoring the warranty. From my experience if you identify a problem for a manufacturer they'll almost always say NO, they will not honor the warranty.

I think I may try to remove the cover of the Iota DLS and see if I can tweak the voltage down 0.4 volts, which would put the charging profile in the sweet spot for the Lifeline batteries.

do you have docs, examples of how to do that? Sounds interesting!

 

[Jack]

A Victron DC-DC charger (highly recommended over Redarc and Renogy) will set you back about $225 and a couple of hours of time. Running heaver gauge wire from the truck to the battery separator costs fewer $ but a lot more time. And when you upgrade to a new truck with a smart alternator (if not already), the thicker wire won't help. If you go to lithium batteries, the DC-DC charger can also take care of the Iota issues.

I posted my installation of a Victron DC-DC Charger - it was relatively easy

https://www.wanderthewest.com/forum/topic/20049-installing-dc-dc-charger-in-2015-fleet-fd/

 

[ntsqd]

When I first wired our truck almost 10 years ago I ran 6 ga. wire to an Anderson connector bolted to the inside of the bed. I continued with 6 ga. into the camper and on to the batteries (6 VDC T-105's in series). I choose 6 ga. because I wanted to support up to 80 amps with no more than a 3% Voltage Drop. Not just for charging, but for other things like an On-board Air compressor sitting on the side of the frame almost directly under the Anderson connector. The bulk of that wiring will stay with the truck until there's cause to pull it out. Likely long after I care one way or the other.

DC-DC was looked into then, did not exist in a practical way.

With a simple 100W solar panel on the roof of that first camper the connection to the alternator was almost redundant. Only when we seriously drew down the camper batteries was the alternator connection of much use. Given that, my advise would to not build an over the top alternator charging system. Instead build an over the top solar charging system. If you're in a region where the sun isn't available frequently only then I'd put more effort into the alternator charging system.

 

[Stokeme]

X2 directly above ... “Over the top solar charging system”, or some semblance of that. But, I was able to start with a Shell build & plan for low Ah usage. Less weight, less wiring, less gadgetry. Consider, anyway, putting $ into more solar. Unless, also as stated above, your FWC usage is frequently in a region where the Sun has availability issues. It has kept things simple for me. Get good panel(s).

 

[Bwht4x4]

I agree about over the top solar charging system. I've personally never had an issue with the FWC wiring under the truck to the batteries. Generally I camp/hunt for one to three weeks straight and generally in areas where there's a lot of sun. I have a 160 watt panel on the roof and I deploy a 100 watt once I set up camp. Never had an issue so far.

My main concern is charging the batteries when the camper is stored for weeks or months at a time. I want to ensure the existing Iota DLS charger is going to provide a charge profile that will allow me to get maximum lifespan out of them. I am still leaning toward slightly adjusting the voltage of the Iota DLS through the potientiometer to see if I can reduce the overall voltage for all stages 0.04 volts.

 

[ntsqd]

FWIW I have a battery tender (NOCO Genius in the current camper's case) that is permanently part of the camper. Haven't gotten to it with this camper, but in our old one I added a dedicated outlet for the battery tender so that it went live when ever we plugged into shore power. After finding the "converter/charger" in the old camper boiling the batteries I've no trust in them at all. I have read of a supposedly good one, but I'm not interested. A purpose built battery charger makes more sense to me.