How much is too much?

Dutch061

Okay, for all of those who never wanted Amp Hours or battery capacity to hinder them. If you remove the cost from the equation, what would you do?

IE

How many Amp Hours of batteries would you have?

How many watts of Solar Power would you have?

P.S. There is a reason I ask this question and will post what I decided in the next few weeks when I get it completed.  

Brad

SLJ

Everyone's use and needs vary. I'm planning on adding a second 100 AH AGM battery and a second solar panel to the roof. I want a minimum of 1 watt of solar for every AH of battery. The more, the better.

DenverJaguar

I think 300AH would be great, but only if/when battery tech advances enough to bring down the weight and size of the battery. And then have 200-300 watts of solar. 

bergger

As mentioned previously power needs vary from person to person.  We have a 2021 400 and I believe it has around 224 AH and the standard solar, somewhere around 162 watts.  We run lights, stereo, watch movies and occasionally use a small drip coffee pot off the inverter.  We have never come close to running our batteries down and they have always topped back off with solar rather quickly.  The stock setup works well for us and I see no need for any more.  But if the sun ever stays hidden for a few days we do have a 200 amp alternator in our truck that we could use to help charge things back up as well.  Unless you need tons of power I would not invest anymore in the trailers batteries or solar.  But if you wanted more solar power I would just add a solar port and solar suitcase and or upgrade the alternator on your TV.  

ScottG

I have a ~100aH wet cell battery and a 100W portable solar panel. While I often daydream of adding more capacity, for seven camping seasons this set has proven to be "too much" 100% of the time.  ;-)

WayneW

Like @ScottG, we are minimalists when it comes to power needs. I removed the television and we are seldom in areas with radio reception. So we need power for the fridge, fan, and lights. We still have the stock 85 aH wet cell which is marginal at best and will soon be gone. 

I’ll probably upgrade to a 100 aH lithium next year. We have stock rooftop solar and a 100w Renogy solar suitcase which we had for a previous T@G. That will likely more than meet our needs. I could throw caution to the wind and get a 150 or 170 aH battery but I probably won’t. 

pthomas745

My 2017:  propane fridge, 100 watt panel and stock 80Ah battery.  Once I figured out how to deal with monitoring, that combo worked fine.  I did start carrying a small 30 ah battery to take care of laptop power needs.  Never came close to having any issues with up to 55 ah to use.  Just had to transfer the solar controller over to the small battery when needed.

The 80 ah was just taken out of the trailer after 5 years.  It might be a little shaky.  I was going to upgrade to a 100ah AGM, but I discovered that some lithium 100ah batteries are now below the 400 dollar mark.  (No bluetooth BMS systems, no "freezing charging battery protection").  So, I bought one.  So, now I have about 90ah to use....and for me this is probably twice the capacity I need.   But.....my 3 way fridge had issues handling a big heat wave this summer, so I'm thinking a small Alpicool portable fridge is in my future, and I expect my setup will be able to handle that possibility.

I think the "sweet spot" for a well monitored system with a propane fridge is 80 ah with a 100 watt panel.

VictoriaP

Solar isn’t one size fits all. If you live & camp further north (especially here on the wet side of the Cascades), camp under trees regularly or during the off seasons, or have high power usage, 100-200 watts may not be enough without conservative energy use. I love data, I really do, but I don’t want to *have* to monitor my usage constantly.  I want to be able to pretty much set and forget regardless of weather or where I’m parked. A 100 watt panel often produces not much more than a trickle charge around here. 200 watts and 200 usable amp hours, preferably lithium, would be the bare minimum I’d like on my Tab 320 (propane fridge). Currently I’m at 100w portable and a 2 year old 105 ah AGM that I’m willing to run down to 20%, so I’m eyeing upgrades. 

My true ideal would be enough to be independent of the power grid entirely for an indefinite period with a 12v fridge, induction burner, microwave/instant pot/toaster oven, and running the AC several hours in the evening daily, using propane only as a heat source. But I’m not willing to completely cover the tiny Tab roof and my car in panels or fill all my storage with batteries. That goal is saved for changing to a class B and fulltiming somewhere with more optimal solar conditions. Someday.

Marceline

I have a 2way fridge so if cost wasn’t a consideration I would have 200aH+ of Lithium and 200-300 watts of solar power. 

Denny16

The minimal solar panel size is going to depend on the size of your battery bank.  As mentioned, 100 watts for 100 amps of battery.  But this is going to depend on your location and available solar coverage on the panels.  In Victoria’s Pacific Northwest location, I would double the solar panel size, to 200 watts per 100 amps of battery to optimize the solar charging, depending on my load requirements.

The second consideration for the size of a battery bank, would depend on your DC energy requirements.  I have a TaB400 (Jan 2018 build) thst has factory 103 watts of solar on a 200 amp AGM battery.  My current loads include a two-way fridge, lights, occasional radio, and exhaust fan (upgraded to more efficient 8-speed unit), and from late spring to early fall (March to Oct) this setup keeps the battery charged to cover the current use.  If I want to add a microwave or induction cook top, I would need to increase my battery bank to a minimum of 300 amps Lithium, and have a total of 300-400 amps of solar panel capacity to run a 2/3K inverter setup.  The factory 1800 watt inverter doesn’t run a small microwave, a full 2K Inverter is the minimum size needed for lager load appliances, like a 700-watt microwave.

So the size of battery bank and solar capacity is going to be a very individual requirement, based on what you want to use in the TaB and how long you want to camp off grid.  What works for me in Northern California might not work for VictoriaP in Washington state area.  

cheers

Dutch061

Okay, so here is what I decided to do. Since we camp mostly off-grid and often in shady sites, I had 3 choices I could make.

1. Leave it alone with 200 Ah of BB Lithium and use a generator every 3 days +/- for 3 hours to charge.
2. Buy a Solar Suitcase and have more stuff to load, haul, deploy, and unload when I get back home.
3. Add additional Ah of BB Lithium

Since my greatest challenge with using option 1 is that I have ended up in places where running a generator isn't allowed. Happened again in September when we were in the Grand Tetons, somehow I managed to book a site in a loop that didn't allow generator use. Reservation was for 6 days and to further complicate things I was at 50% State of Charge when we arrived. So I knew that making it 6 days on the Solar Panel that was partially covered and not facing the correct direction wasn't going to happen and not having the ability to use a generator to charge with that I was in trouble. This caused a lot of extra time and motion that severely distracted from my enjoyment while we we there.

Option 2 is definitely something that is plausible and would work. There are 300 Watt suitcases on Amazon for $300, add in another Victron MPPT Solar Charge Controller and it becomes pretty cost effective at less than $600.00. However, the big distraction again is the messing around that has to be done in getting things set up. Yes, I am retired and have nothing "better to do" but choose not to spend my time doing things like this.

So, Option 3 became my option of choice. I could easily get 6 days (or more) of use without doing anything else even if I am shaded, it is cloudy, or otherwise. There is nothing additional to hook up, load, move, mess around with or otherwise. In addition, I don't have to be a miser constantly worrying about how many Amp Hours of electricity that I am using. I use an inverter to make coffee and toast every morning. That isn't going to change and to constantly be messing around with a spreadsheet (I know some people get their kicks with this) isn't something I want to do. I done enough of that when I was working, it is time to enjoy and be stress free while we are enjoying.

Below are a couple of pictures of my project. First picture shows the battery tray that I made from High Density Polyethylene to set the additional batteries on. I used stainless steel screws to hold it together and to mount it to the floor.



The second picture shows the tray installed and the batteries in place and connected. I also placed a plank in front on the top to prevent the batteries from having the desire to try and move. This is held in place with 6 pocket screws on the back side, 3 on each side. 

The battery cables are 2/0 gauge. So up to the junction block, everything is 2/0.

You can also see my relocated converter, a PD9260CV that has the pendant. The Pendant allows me to force the Bulk Mode (14.4 volts) to properly charge my Lithium Ion Batteries. I had thought about swapping that out with a 9180 that is made for lithium and still may, it would reduce the time to charge by about 25%. However, with the relocation and the 4 gauge cables to the junction block, I can fully charge 400 Ah in less than 7 hours. 



I still have some space in front to keep a few things. We never put anything under the bed outside of paper products anyway. IE Paper Plates, paper towels, or spare rolls of TP.

Anyway, looking forward to giving this the test in the next 2 or 3 weeks.

Brad

Michigan_Mike

Looks pretty solid to me!  😀   Let the fun begin!  

pthomas745

The Zebra pen really completes the install.  (if it is one....!)

Dutch061

The "Zebra pen" is the flux capacitor, it makes time travel possible. 

CrabTab

Elegant looking solution to the common issue @Dutch061. Being added to the other side of the axle, do you anticipate any changes to the tongue weight?

Dutch061

I suspect there is a change to the tongue weight. There would have been a change just removing the 2 AGM batteries that weighed 134 pounds going to the first 2 BB's that weigh 62 pounds. This probably had as much effect on the tongue weight as adding 2 more at 62 pounds. So my Ah capacity is 2.5 to 4 x higher (depending if you use 50% or 70% discharge) with 4 BB's than with the Harris AGM and I lost 10 pounds overall. 

So, how much did the tongue weight actually change, could probably do some math and figure it out or take it to a scale. Overall, I don't think it changed it that much.

I am using a 2021 F-250 with a Power Stroke Diesel as a TV, so tongue weight is not much of a concern.

Brad

CrabTab

Dutch061 said:

I am using a 2021 F-250 with a Power Stroke Diesel as a TV, so tongue weight is not much of a concern.

HAHA, that surely is not an issue for you!

I only posed the question trying to learn more about 400s in general. I guess with the lighter weight of the lithium batteries it is pretty much a wash anyhow.

Thanks...

Dutch061

@CrabTab, as I take another look at the batteries, all 4 are behind the axle. The 2 added batteries are not as far back as the originals but still to the rear of the axle. So, I suspect the overall impact is very minimal.

Brad

DenverJaguar

You have so much space for batteries in the 400! I have two BBs crammed in the passenger wheel well area. I don't think they'd have fit by the AC unit, but one good thing is they are right over the axle.