What battery should I upgrade to?

ScottG

@BrianZ, I've eyeballed @elebereth's excellent mod as well, but I think you are right about it not fitting with the sewer tube mod. Guess ya' can't have it all!  :-)

I haven't taken any actual measurements though, so if you investigate further and figure out how to make it work, I'm all ears.

Sharon_is_SAM

Brian, that is a box of gloves stuck to the inside lid.  Smart place to make them handy and looks like they are in a plastic box to boot.

BrianZ

I did a test fit of the Noco group 27 box in the photo below, and it looks like it should fit fine & will hold a Trojan T-1275 150AH battery using the wood block method to fill the old frame & bolting on a new frame at an angle like you did, @ScottG.  This battery is available from a local golf cart shop for around $200 and should satisfy our occasional need for more power without hookups.  An AGM battery would be nice to have, but unfortunately won't easily fit our situation.  I may add solar at some point for extended power, but right now just trying to prepare for a trip in a couple months.


I wonder if there would be more usable space by moving the battery switch to where the gas regulator is, and moving the regulator to the left corner.  Even one inch could give more options.

Thanks for pointing out that clever glove box mounting, @Sharon_is_SAM.  That could solve one storage issue caused by the new battery box.  Still have to find a spot for a couple of sewer hose connectors, but I think there may be room left in some corners.

elbereth

@BrianZ, the cable looping over the propane tank is my quick disconnect for my solar charge controller, and as @Sharon_is_SAM said, I have a box of Camco gloves stuck to the lid of the box.  Moving the propane regulator to the outside side of the tank was super easy, and I just used a little caulk to fill the holes in the diamond plate where it had been before.  

I am pretty sure there isn’t quite enough room for a sewer hose storage behind those two batteries.  You can see I still have the factory-installed length of PVC pipe for the cheapy sewer hose in the picture, though I did the tongue storage box mod just this week to store a better stinky slinky and attachments.  Even if I take the PVC out, I’m not sure there’s enough space for a battery box to fit 2 GC batteries in there - I really like your solution and 150 Ah is a decent amount of power!

BrianZ

Well, I finally got this battery mod done..
I could not find a 12 Volt Trojan Plus battery locally, so I bought the slightly taller model T-1275 with 150AH for about $216 at a local golf cart store.  It would have been $45 cheaper if I had an old battery core to turn in, but had to pay the "deposit".  I will just keep the year-old stock battery & bring it along for an extra 75 AH of emergency backup.  I could put in in the rear storage when not charging to offset some tongue weight.  And speaking of that, I weighed our tongue after removing the old battery and it was 178 lbs with spare tire, before adding the new 85-lb battery, so we'll still be under 265 lbs, which should be fine.


After removing old battery


An 11-inch long piece of treated 2x8" lumber had the perfect 7-1/2" width to fit the old frame, with a thickness that was about 1/4" taller than the larger piece of metal framing, so perfect for keeping a new battery frame supported above the old one.


I made a template from a piece of scrap matboard used for framing photos, to match the 7-1/2 x 13-1/2" footprint of the Group 27 battery box, and used that to layout the locations of where to drill holes for bolts that would go through the old frame, wood block, and new frame.  I used 1-1/4" steel angle iron to make the new battery frame shown above after drilling & welding at a local welding shop, before sanding & painting with rustoleum.


I had to add an extra small block of wood for one of the 1/4 x 2-1/2" stainless bolts.  For the locking battery strap (from the old battery - the new box came with a less convenient buckle), I was able to easily pass the strap under one side of the new frame, but for the other one I chiseled out a 3/16" deep slot into the surface of the wood block.


Also added a piece of 1/4" outdoor grade of plywood which allowed the box to sit level over the unevenly placed bolts & framing.


The box has a good pair of handles, and fortunately I was able to lift it with the 85-lb battery into the tub without injury.  We have a healthy 28 y/o son who was on standby if needed, so hope he'll still be available 7 or 8 years from now.  The battery voltage read 12.25 before hooking it up & good water levels, so was in ok condition.  The dealer said they get shipments every two weeks directly from Trojan, so they don't need to charge them routinely.


The new battery has hooks for lifting, so I made this simple carrying strap using a piece of rope, pvc pipe, & S-hooks.  Worked great for lifting it into the box.


Finished mod, with no room to spare so measure carefully if you do this!  The box lid would only snap closed on one side, due to battery height being about a half inch too tall (which is why I had wanted the shorter "Plus" model), so the other locking tab sat up about a half inch too tall to snap shut, but it still fit inside the provided slot so the strap holds it all snugly in place inside the frame.

Next I'll try to find a place for hose connectors & gloves, and then I'll start thinking about solar panels.

jkjenn

Very nice fab skills, there, @BrianZ! Looks freat!

BrianZ

Thanks, @jkjenn!  I wasn't even trying for "freat"  but glad you like it.

Now we need to figure out a plan for a test trip to get a feel for what we can & can't do and for how long.  Will have to wait until A/C season is done & maybe wait until we might want to use the Alde.  We've actually never gone off-grid with our T@B, so have never even tried using the Alde or frig on propane, or had to depend on the fresh water tank for that matter.  I guess we probably should have at least tested the gas appliances before the warranty expired. 

jkjenn

BrianZ said:

Thanks, @jkjenn!  I wasn't even trying for "freat"  but glad you like it.

Now we need to figure out a plan for a test trip to get a feel for what we can & can't do and for how long.  Will have to wait until A/C season is done & maybe wait until we might want to use the Alde.  We've actually never gone off-grid with our T@B, so have never even tried using the Alde or frig on propane, or had to depend on the fresh water tank for that matter.  I guess we probably should have at least tested the gas appliances before the warranty expired. 

Nothing like being able to take a hot shower in a  Walmart parking lot to break in the Alde. 

Seriously, though, you will be amazed at how much capacity you get with those batteries. Gettibg ready for my fall trip and although my solar is now in order, I recognize that the weather can be overcast in Colorado in the fall and I am really happy to have the big battery capacity.

Spectre9

I’ve got a surplus Eaton PWHR12280W4FR - basically a G24 80AH but extreme stability and high current capacity.  $55 locally surplus from UPS lease.

Its self discharge rates are insanely low.

Eaton has 115# ones that were like 140Ah?

It’s going in my TAB after running off my portable solar for camping.

OpenSky

I bought a Renology Group 24 100AH LiFePO4 battery, and thus far am VERY happy with it.  Expensive, but it fits in the factory box, is half the weight, and is equivalent to a 160 AH to 200 AH Lead Acid battery in terms of capacity. (The difference depends on who you believe about running down an LI Battery).  A Lead-Acid battery should never be drawn down below 50 % capacity, so the factory group 24 provides 35 useful AH.

LiFePO4 works fine with standard lead-acid chargers, and should last much longer than the original lead-acid battery did.

https://www.powerstream.com/LLLF.htm

https://www.powerstream.com/lithium-phosphate-charge-voltage.htm

No maintenance. I have an 18W solar cell attached to the T@B cover which maintains the battery charge against phantom loads in storage.

ckjs

@elbereth, I'd love to put your setup in our new 2018 T@B 320 CS-S -- (yahoo!) --  but I'm worried that the tongue weight would be way over the 200# spec of my very-similar-to-yours 4-cyl 2013 Subaru Outback.  How do you deal with that weight?

TerryV6

BrianZ said:

Nice setup, @elbereth, that's great to hear (& see)!  What's hanging over the gas tank - is that a solar connector?  Did you relocate your gas regulator to the other side on the diamond plate?
I'm not sure this arrangement would work for us, because we have a sewer hose carrier tube mounted behind the tub, and it looks like your battery arrangement might make use of that space?
Thanks for sharing, and glad to hear the WFCO charger is working fine for you too.

I'm nowhere near making any battery change at this point.  Still have my stock 24.  I've read a lot of the links provided here..   My question for you basically is:

Was your sewer hose carrier the reason you went with your Group 27 purchase instead of the two 6volt battery setup?  It seems that the latter is more desireable maybe?  The 27 would be a nice bump up for me though.  I suppose the 6volt setup would be more money also.  If so, I'd probably be happy with your system.  We don't travel off the grid much.  I'd have to find a friend to make me a frame...

elbereth

@ckjs - tongue weight is still only about 185 despite the battery being much heavier than the original.  I don’t remember all the specifics, but I think in the end it only added about 30
pounds to the tongue weight - has to do with the geometry of the distance of the load from the axle.

BrianZ

Hey, @TerryV6, yes it was part of the reason, but not the sole reason.  Like you, we don't expect to go off grid much, yet wanted to have that option, and having more Amp-Hours available makes an occasional off-grid trip possible.  However, we don't expect to go for more than a week at a time, and I feel that supplementing with some solar will extend our capabilities & ability to get by with the 27, while also extending battery life by avoiding frequent deep cycling.  We're starting with a 100W solar panel, but could add more later if we should need to recharge faster. 

The two 6V batteries do give 220AH which would be best for longer stays, but they take more space that we don't have, and I didn't want to get a whole new tub setup if we really don't need it.  This just seems like the right option for us for now, unless things were to change.  On the other hand, maybe two 6V could be an alternative to also adding solar, if total cost is the primary concern, or if longer boondocking trips are a possibility and solar could be added later.

The frame isn't hard to make if you have a hack saw, good drill bits, and can find a welding shop.  The part that takes the most careful attention is getting the right angle & position to both fit the box into the space while at the same time overlapping the old frame such that bolts can be placed in strategic spots to go through both old & new frames.  Not difficult, just requires careful attention.

Mouseketab

rfuss928 said:

I have had very good results with Optima Blue Top batteries.  I fit a D31M in the original group 27 box with no trouble. 

Optima blue top batteries (spiral AGM construction) are know for higher power density, extreme vibration resistance, significantly longer life and zero maintenance compared to flooded lead acid batteries.  They are a premium battery with a premium price but in the long run are less expensive to own because of their long life.  These were the batteries of choice in industrial/commercial power back up systems I worked on.

I am on my fifth camping season with two D31M batteries and they continue to perform as new.  I have not even seen them since I screwed the cases shut in 2011.

I also put in an Optima Blue top 31 a few years ago, and it has been really problem free. I have the 12V fridge, and have no problems with it staying charged while driving. I also have a power mover which is a bit of a battery hog, and the battery has never failed me when I need to move the camper around. (I don't boondock, so always have Shore Power at my destination, and have a 30 Amp plug at home.)

ChanW

@elbereth, nice installation.

A couple of questions... It looks like it's a tight fit. Do you have any binding or rubbing issues with the battery on the diamond-plate, propane tank bracket, or the box?

Also, what is the strap anchored to underneath? Enough to keep the batteries from bouncing?

Thanks!

elbereth

@ChanW, it is a super tight fit.  I’m not seeing any marks on anything, so I think it’s so tight there isn’t much movement and it all kinda moves as a unit.  The strap just wraps around the old frame with plywood in it - it’s actually not even super cinched down, so I really think it’s the friction of everything wedged in there.
We haven’t done hundreds of miles of washboard or anything, but have been on dirt forest service roads as well as at highway speeds on the, well, highway, and everything stayed comfortably in place.

ChanW

Ok, thanks @elbereth. I think I'm gonna try using a couple of 10# propane tanks, and work around those. We'll see!

Scotty49

We recently installed a Battle Born 12V 100 AH LiFePO4 battery in our 2018 T@G Outback. It came with a Group 24 75 AH battery which was not adequate for our boondocking requirements despite a 120 watt Zamp solar siutcase. The install was simple. The battery fits into a Group 27 box in the front of the Outback, works nicely with the solar panels and can be charged (albeit not fully) with the WCFO converter if we happen to be plugged in (rarely for us). I also purchased a separate Progressive Dynamic 9130 LV battery charger for when we are at home and a Victron 700 BMS battery monitor to assess the state of charge and amp/hour consumption on the road. The battery weighs only 29 lbs. As stated earlier in the thread, LiFePO4s allow you to utilize 98-99% of the battery’s capacity before requiring a full charge and are touted to have 3000+ charge cycles over the life of the battery. IMO our other option was a two 6V golf cart battery (200-235 AH) system which would have required some modifications of the front tub and likely down-sizing the propane tank. Also, the additional weight of the two batteries (50-65 lbs each) would seriously have increased our tongue weight. Hence the rationale for going with the lithium choice. Attached are some pictures following the install.The cost of the battery was $949, the Victron 700 $147, and the battery charger $201. 

WilliamA

Scotty,
I'll probably get flamed for this, but of all the zany, mad-scientist-esque battery configurations I've watched come across this site, the lithium option is the ONLY one I would personally consider if I were to up-fit my volts.  I looked long and hard at doing that but my RV dealer was peddling them at that time for fafafafafafive huhuhuhuhuhundred bbbbbabababucks!! (I'm sweating profusely just saying it....) I was more in love with the light weight and draw-down potential, which essentially doubles available capacity in the same given volume for a third of the weight.  That said, I've not once been left hanging without voltage in my stock battery and have spent waaaaaaaay too much time trying to work out how folks even use so much power!??  Good choice! I approve!

In the meantime, I'm just sitting here with my bag of popcorn, waiting for the day when someone figures out how to install a 380 volt, 40 amp wind turbine on a 50 foot, hydraulic telescoping mast.  I know it's comin...

"Honey, hand me those forklift batteries, welding cables and that 13.2 gigawatt capacitor.  Oh, and my welding mask and gloves. I'm gonna make some coffee..."

WilliamA 

N7SHG_Ham

@WilliamA On a solar RV site there is a guy who put a Tesla battery in his unit! Apparently those and packs from other electric cars are being used and so you aren't far from reality! Right now I am debating the merits of trying to order a 400 with a pair of the Battle Born Batteries! If they could be swapped in at the factory, I belive the cost difference may be about $1200-1500? Of course that is also going to require a different charging system for optimal life, haha.

TerryV6

Hey @BrianZ, here it is March, we have more snow than we know what to do with, and it is below zero...  A great time to be thinking about camping, right?  Anyway, my camper is in storage and probably won't be freed for a month or so, so I spend time visiting this site.  I saw this discussion again and I wondered how your group 27 and its mod is working for you.  Your new box holder was welded together, but I was thinking that it could be bolted together too.  I still have the original and I'm always looking at other options.  We rarely go for more that a week at a time.  It is very cheap to look at stuff, as long as the credit card stays in the wallet...

ScottG

Hey @TerryV6, I don't weld but I can drill with the best of 'em, so I bolted mine together just as you describe. Attachment to the frame was similar to what BrianZ did. The hardest part wasn't so much the construction and mounting, but rather figuring out the exact best position for the box, as it's a bit of a tight fit.

There's some photos of my install in this discussion.

I did have to relocate my frame forward just a bit when I completed my BrianZ inspired sewer-hose carrier mod. Just something additional to consider if installing such a carrier is also on your radar.

BrianZ

Hi @TerryV6!  Glad you are surviving that cold winter up north.  I can only imagine, but our nights are in the 20's here in VA lately, so not quite time to de-winterize yet either. 
I see Scott has verified for you that bolting the battery frame together without welding works fine too, but we just happen to have a welding shop nearby that is reasonably priced.  I tend to over build stuff too.

We've actually only had the one off-grid trip so far, in late Oct when we had to rely on our new battery & solar, and that went really well.  We had one more trip after that before winterizing but had hookups.  Our box is a Noco group 27, but the battery is a 12V golf cart battery, a Trojan-1275, 150AH.  Their 1272-Plus is a better fit for the box with shorter terminals.  Ours prevents the box lid from snapping shut on one side, though it stays on snug with a good strap.

I am looking forward to putting it to the test again this season, and feeling confident even with just the one solar panel.  Let me know if you have any questions, or search on "First Boondocking" for my October report & links to other related writeups.  Very happy we did that & got the solar/charger & battery monitor.  

BrianZ

SweetlyHome said:

@scottg and @willA I have given this some thought as well.  IMHO it has to do with voltage drop in the TV charge line and the relative voltage of the battery as the battery and TV are parallel.  I applied the current squared times resistance calculation and got roughly a 1 volt drop in 15 feet of 10 gage wire at 10 amps.  The 13 volt alternator output is 12 volts at the battery and fridge at 10 amps draw. I stand corrected if I messed up the math.  The battery discharges trying to hold the voltage up, losing the ability to do so as it discharges.  Is there sense my thinking?

I'm a little late here, but I checked your math for ya, @SweetlyHome..
I used the online calculator.. 
https://www.calculator.net/voltage-drop-calculator.html
..and checked theirs too by looking up the resistance of copper cable, which conveniently is one ohm per 1000 ft of 10AWG cable.  So 15ft is 0.015 ohms, and plugging into Ohm's law, V=IxR:
V=10A x .015Ω = 0.15V
x 2 conductors = 0.30 V drop or 12.7V
at the battery.
Your idea seems like it could be a contributor to a lack of charging from the TV, but I'd say not a very significant one (2.3% loss).

BrianZ

Oh, and reflecting back on our first dry camping trip last Oct with the 150AH Trojan golf cart battery plus solar, I realized I had some data from that trip that relates to an earlier discussion about some TVs inability sometimes to keep up with charging the RV battery, particularly when running the frig on DC.

We ran our frig on propane that trip, and left it running on a nearly empty tank for the trip home.  While checking out at the dump station, I grabbed these screen shots of the Victron solar & battery monitor status reports that show charging data.  They were saved about 30 seconds apart..


The battery monitor at left shows 152W and 11.3 amps of charging at the battery, while the solar charger at right shows 5 amps of that is coming from the solar panel.  So, it appears the TV is contributing 6.3 amps.
Wish I had tested the frig on DC to see what effect that would have on charging, but we were trying to use up the remaining propane on the way home, since our local refill station only refills empty tanks.  Maybe next time, but at least we know our vehicle can contribute at least 6+ amps even while a solar panel is connected.