Questions regarding "So, you want to setup a good electrical system in your camper?"

[BrianG]

Thanks Vic, please “more later” I have a company in Reno upgrading my original 2015 Hawk AGM setup to LiFeP04 in April. Between now and then I’m trying to become as knowledgeable on the subject as possible. And thanks to everyone on the forum for their input over the last couple months.
Brian

 

[A.Smith]

Thanks Vic, please “more later” I have a company in Reno upgrading my original 2015 Hawk AGM setup to LiFeP04 in April. Between now and then I’m trying to become as knowledgeable on the subject as possible. And thanks to everyone on the forum for their input over the last couple months.
Brian

Brian, What company in Reno ? And which components and brands are you having installed ?

I am trying to install a solar and Lithium battery system in my 2006 Hawk. It is an adventure to be sure.
Thanks to Vic and Rando, and countless others I am learning.
Thanks
Fred
A.Smith

 

[Vic Harder]

Please post your questions here instead of in the main thread.... thanks!

 

[BrianG]

A. Smith, the Reno company is:

www.sixguntwelvevolt.com

Zero Declination

They will be installing one or more Battleborn batteries, Victron Orion-Tr 12/12 Volt, 30 amp, DC/DC Charger, MPPT 100v 30 amp 12 Solar Charger and the 712 monitor. Plus 4 gauge wire from engine to camper.

 

[Lighthawk]

Very clear write up, Vic!
You may not realize how much value you bring to the forum with your concise and informative writeup.

We've also upgraded to a 100ah LiFePo4 after going through two AGM batteries in ten years on our 12 year old camper.
Luckily our MPPT solar controller and FWC Iota charger were compatible with minor adjustments, so it was plug and play.
DC-DC chargers are certainly an interesting option.

I'm bookmarking this thread for future builds.

 

[rando]

Is the 50% 'usable capacity' the right guideline for a truck camper?

One comment or point of discussion for the 'How Much Battery do I Need' post - I know that only using 50% of your lead/AGM battery is a common rule of thumb, but I am wondering if it is the best guidance for a truck camper in which weight is an important consideration? The 50% guidance is based on an economic balance between the life of the battery (the deeper you discharge on each cycle, the less cycles you get) and usable capacity. It doesn't really take into account weight and the fact that you are only using half the battery you are hauling around.

Based on a typical AGM depth of discharge vs cycle life curve, then maybe going to 80% makes more sense in a truck camper, particularly if you aren't living in it full time. For a weekend warrior who does a ten 3 day trips a 3 two week trips a year (~65 nights per year) then even using 80% of the battery could yield ~650 cycles and 10 years of use. It is also important to note that other things can also reduce the battery regardless of depth of discharge - delayed recharge after use, high temperatures, and old age (calendar life) so regardless of the number of cycles a battery will typically only last 5 - 8 years in 'average' use.

Going to 80% DOD gives you 60% more usable capacity essentially for free in terms of weight. For a heavier user, the battery may only last 4-5 years a 80% DOD rather than 8-10 years at 50% DOD, but you also only had to buy one battery, so the economics aren't that different.

Source: https://www.cedgreentech.com/article/how-does-depth-discharge-factor-grid-connected-battery-systems

 

[A.Smith]

A. Smith, the Reno company is:

www.sixguntwelvevolt.com

Zero Declination

They will be installing one or more Battleborn batteries, Victron Orion-Tr 12/12 Volt, 30 amp, DC/DC Charger, MPPT 100v 30 amp 12 Solar Charger and the 712 monitor. Plus 4 gauge wire from engine to camper.

Brian, Looks like a quality build. And must admit you will be on the road much sooner than I. Doing all myself means lots of time, and mistakes, oops I bought 10 gauge, I wanted 8 gauge, Enjoy the Travels
On the Adventures
Fred

 

[Vic Harder]

I agree with you completely rando. Details like this are important, and may also confuse the folks new to battery systems. I also wonder about this chart... as it indicates we can expect 500 cycles if we flatten (drain to 0%) the batteries every time. That seems overly optimistic. Now, that could be because I live in a cold climate and a dead battery will freeze, and the freezing will kill a battery for sure.

I'm open to revising my post to say "50% to 20%" SOC for lead acid batteries, yet I wonder why the "standard" I see stated most often is 50%?

 

[craig333]

I expect ten years of battery life because I rarely go below 85% S.O.C However having the amp hours to accomplish this also means that when I do run into days of bad weather I'll have enough power without having to fire up the engine or run a generator to avoid running my batteries too low. I do suffer a weight penalty to accomplish this but since I have a big heavy diesel this isn't an issue. If I were driving a half ton truck I'd definitely want to spend the extra for a lithium phosphate battery.

The 50% number is certainly arbitrary but I think its a reasonable compromise. I really like having a large reserve but if that isn't a concern you certainly could save some money with a single battery.

Wouldn't a longer life span also be a little more environmentally friendly?

 

[rando]

One thing to remember is that running the battery down to 0% SOC does NOT mean 0 volts, it is pulling the rated capacity (which will decrease over time) out of the battery. Typically this means taking the resting voltage down to about 10.5V.

I agree that the USBattery chart seems a bit optimistic, but I think it is for true deep cycle AGM, not the dual purpose or marine AGM that most FWC come with. Either way, the idea holds - maybe you get 600 cycles at 50% DOD and 350 at 80% DOD, the curve looks about the same.

I agree with you completely rando. Details like this are important, and may also confuse the folks new to battery systems. I also wonder about this chart... as it indicates we can expect 500 cycles if we flatten (drain to 0%) the batteries every time. That seems overly optimistic. Now, that could be because I live in a cold climate and a dead battery will freeze, and the freezing will kill a battery for sure.

I'm open to revising my post to say "50% to 20%" SOC for lead acid batteries, yet I wonder why the "standard" I see stated most often is 50%?

 

[rando]

I expect ten years of battery life because I rarely go below 85% S.O.C However having the amp hours to accomplish this also means that when I do run into days of bad weather I'll have enough power without having to fire up the engine or run a generator to avoid running my batteries too low. I do suffer a weight penalty to accomplish this but since I have a big heavy diesel this isn't an issue. If I were driving a half ton truck I'd definitely want to spend the extra for a lithium phosphate battery.

The 50% number is certainly arbitrary but I think its a reasonable compromise. I really like having a large reserve but if that isn't a concern you certainly could save some money with a single battery.

Wouldn't a longer life span also be a little more environmentally friendly?

That is the trick right, to get the longer life cycle, you are typically using about twice the battery, so they do last longer, but there is more of them to recycle. The total number of amp hours you get out of the battery over its life using either depth of discharge is about the same.

 

[A.Smith]

My question is; How best to connect different gauges of wire ?

My solar panel has a 2 foot piece of 12 garage. I am running 8 awg from the controller to the solar panel.
How best connect these two different gauges ?

Thanks
Fred
A.Smith

 

[Vic Harder]

Fred, that's a short piece of 12G. And it will be on your roof, correct? You want to keep it out of the elements for sure. A number of methods come to mind:

1) Butt connector - the problem is that 8 to 12 is a big jump and the same connector won't likely work for both. What i've done in the past is to get an uninsulated butt connector and spread the end that is too small before inserting the wire and crimping it. Insulating it with weather resistant heat shrink.

2) Surface mount box. Another option is a small surface mount plastic box that you can run the wires into, connect via wire nut and then seal with Dicor or a polyurethane caulk.

 

[A.Smith]

Fred, that's a short piece of 12G. And it will be on your roof, correct? You want to keep it out of the elements for sure. A number of methods come to mind:

1) Butt connector - the problem is that 8 to 12 is a big jump and the same connector won't likely work for both. What i've done in the past is to get an uninsulated butt connector and spread the end that is too small before inserting the wire and crimping it. Insulating it with weather resistant heat shrink.

2) Surface mount box. Another option is a small surface mount plastic box that you can run the wires into, connect via wire nut and then seal with Dicor or a polyurethane caulk.

Thanks Vic, much simpler than my over engineered wonders.

 

[PaulT]

On the smaller wire, strip twice as much insulation as you would normally. Fold the stripped portion in half and twist to create a larger diameter end section and use that in your butt connector. It is not ideal but will likely work fine.

Another approach is to crimp each wire into an appropriate gauge ring connector and use a screw, washers, and nut to connect the two ring connectors. Cover the connection with electrical tape and seal with liquid tape or self vulcanizing wrap or adhesive heat shrink.


Or use a step down butt connector like this: https://prowireusa.com/p-3036-step-down-butt-conn-8-to-12-10.aspx

Paul

 

[JaSAn]

I thought wire nuts were a no-no for mobile applications.

I used ring terminals and a 2 stud junction block inside a surface box to connect two AWG 12 solar panels to AWG 4 going to my controller.
Similar to this only for 4 gauge wire:
https://www.summitracing.com/parts/prf-80112

 

[A.Smith]

On the smaller wire, strip twice as much insulation as you would normally. Fold the stripped portion in half and twist to create a larger diameter end section and use that in your butt connector. It is not ideal but will likely work fine.

Another approach is to crimp each wire into an appropriate gauge ring connector and use a screw, washers, and nut to connect the two ring connectors. Cover the connection with electrical tape and seal with liquid tape or self vulcanizing wrap or adhesive heat shrink.


Or use a step down butt connector like this: https://prowireusa.com/p-3036-step-down-butt-conn-8-to-12-10.aspx

Paul

Thanks Paul.
Your information and suggestions are another example why this Group is so valuable.

Fred

 

[Vic Harder]

I thought wire nuts were a no-no for mobile applications.

Hmm, good thought.

 

[anthonym]

Thanks for sharing all of this. I'm new to campers and have been concerned about using systems I don't understand. These resources are great. I'm looking forward to tracing the electrical system with Vic's thread pulled up to get at least a working understanding of what's going on.

For the AGM discharge discussion, the chart Rando shared in another thread looks more conservative (and perhaps more accurate) than the one for industrial deep cycles. It's still very helpful to think realistically about number of nights/year and general service age of the battery vs discharge cycles. Even at the more conservative cycle numbers here, discharging past 50% won't be an issue for my frequency of use for a long time (even considering degradation of battery over time and increasing likelihood of deeper discharges to get the same Ah).

 

[steve whiteside]

Good info Vic and you are a talented writer! Looking forward to the rest. You should be a technical writer!

Steve