Toying with some ideas to increase battery capacity

Maple_Geek

Hello,

Early in the summer I replaced my underpowered lead-acid battery with a 100Ah LiPO4. It was a straight replacement and I re-used the group 24 battery box in the tub of my 2022 T@B 320S.

I'm now contemplating adding a 2nd 100Ah Lithium battery and for now I would prefer to add it in the tub also (that may change later)
I haven't found a dual battery box that would place the batteries in this orientation (II) rather than (--) if that makes any sense (https://www.amazon.ca/Camco-55374-Hardware-Safely-Automotive-Anti-Corrosion/dp/B07QJ2MBRD)
Is my only option to build my own or do they exist and I just haven't found them?
Also contemplating in replacing the 20lbs propane tank with a 10lbs propane tank to gain a bit of room back and reduce tongue weight if needed.

I would appreciate any input or thoughts you guys would have. Thanks in advance

webers3

I am curious about your camping style ie why  you feel you need 2 lithium batteries? I have a 320s and 12v fridge and 1 lithium, with solar supplement I can easily go 1 week without recharging, needless to say my electricity requirements are minimal. 

Maple_Geek

@webers3 When we Boondock, it is generally in heavily treed places where my rooftop solar and my 200W suitcase solar panel don't generate as much as they could so typically, after 4 days with pretty much just the fridge going I'm down to ~10% capacity

MuttonChops

Maple_Geek said:
. . . we Boondock, it is generally in heavily treed places where . . . 200W suitcase solar panel don't generate as much as they could . . .

Make a longer connection cable for your portable panels.
Way, way less $$ then another lithium battery

VictoriaP

I’ve been looking for three years for a box of the kind you suggest that will fit in a Boondock tub. Have yet to see one, hopefully someone else here has. 

Given that when pairing batteries, they need to be the same age, I would confirm with the manufacturer that adding a second one months after the first won’t cause any issues. 

Maple_Geek

Looks like I may have found one. Seems like they are called double side-by-side battery box. 

https://www.camco.net/camco-vented-rv-marine-battery-box-double-side-by-side-55370

VictoriaP

@Maple_Geek That one won’t fit the older era Boondock tub, have you checked the measurements for yours?

Maple_Geek

I have not measured anything yet but I have the new and larger Boondock tub. It is also why I was inquiring about going to a smaller propane tank in the tub. 

I need more watts than I need propane based on this year's experience. 

pthomas745

One option that is always forgotten: an AGM or Lithium battery can be set up in any position except upside down.  They can lay sideways.  They can stand up on the "short" side.  You are not limited to plunking them down so the battery connections face "up". 

This thread is "Anyone Carry A Spare Battery".  There are interesting ways to connect a battery to the trailer that do not involve the tub at all.  (It takes a bit of imagination to be able to set this up and charge the batteries in use, however).

https://tab-rv.vanillacommunity.com/discussion/7008/anyone-carry-a-spare-battery/p1

Someone in a thread showed one of these type battery boxes.  When I added a lithium into the Outback tub, the problem I had was with all the "lumps" of the standard Camco battery boxes.  All those extra lumps and bumps of the Camco just got in the way.  These smooth boxes are easier to deal with...but, a bit pricy.  Look around for their other sized boxes.

https://allbatterysalesandservice.com/century-plastics-heavy-duty-battery-box-holds-1-group-30-h-battery-30h-g

mdrider

I have a 2022 320 Boondock and bought a battery box from the same company that pthomas745 mentions, though I bought from their ebay store (they said the ebay purchase would get to me faster).

I bought this box for my AGM batteries.

Here's a thread where someone else used the same battery box I bought.

Maple_Geek

Thanks @mdrider. I looked at that box but a Group 24 battery typically measures about 11 inches long, by 6.875 inches wide, by 9.5 inches tall so I don't think this box would fit 2 of them. You must have two 6V batteries?

pthomas745

@Maple_Geek they have tons of different size boxes.  I'm sure one will work (or come close).  This is their ebay store.  https://www.ebay.com/str/allbatterysalesandservice2009?_trksid=p2047675.m3561.l2563

Maple_Geek

Thanks @pthomas745. I must be missing something as I only see 3 boxes on their ebay store. I did find about a handful on their web site (not including the bulkier black battery boxes). All the ones I've seen are either too small or too big and therefore it would either not fit in the tub or take too much unnecessary room.

Marceline

It’s good to remember that lithium batteries don’t need to be placed in a conventional vented battery box. I put mine (along with a smart shunt) into a plastic file folder box. Figure out the dimensions of the box you need and then Google those dimensions combined with keywords like “box” or “container.” TAP  Plastics or some other fabricator could also make you a custom box. 

CCC

2022 320 Boondock. I replaced my useless 54 AH with two Battleborn 100s put in the passenger side inside the camper for security. It also opened up room in the tub for an extra 20 lb propane tank I use for cooking outside. Parked in the shade a few weeks ago it ran the fridge and other stuff for about 5 days before the batteries ran out. Think it would run forever with half sun.

Maple_Geek

@CCC yes that's my long term plan if I ever get to it. I live in an apartment so I don't have a space to do project work like that so I may never get to it.  Until then, in the tub it is.

@Marceline yes any plastic container would do since they don't need venting. I just thought something would already exist to fit that exact size. 

stepheng

I have a 2018 320 Outback.  If I replace my deep cycle lead acid battery with a lithium ion battery are there any changes/settings that need to be made to the charger in the trailer? I know I can set my external solar charge controller as required but don’t know if there are any changes that I need to me to charger within the trailer. 

Horigan

The charger on the trailer will only fully charge a lead acid/AGM battery.  Lithium requires a higher charge voltage, so the existing charger will only charge a lithium battery to about 80% capacity.  Also, if the lithium battery does not have built-in cold temperature charge protection, you need to add that somehow for both chargers (trailer and solar) so the battery doesn't get charged below freezing.   Because of this, most folks upgrade the trailer charger when they go lithium.

stepheng

Any recommendations for charger upgrades? Know where the charger is located?

techietab

stepheng said:

Any recommendations for charger upgrades? Know where the charger is located?

It's built into the WFCO power center. Unfortunately, the latest versions with 'auto detect' mode that is supposed to boost the voltage for LiFePO4 batteries are somewhat unreliable. See here: https://tab-rv.vanillacommunity.com/discussion/16210/wfco-wf-8735-ad-lifepo4-fyi-on-annoying-auto-detect-quirk

As such, I wouldn't bother with the power center upgrade if I were in your shoes and looking to upgrade to LiFePO4. Just get a quality high amp charger like the Victron IP22 (30V) and wire it in for a much better experience and faster charging. 

pthomas745

If you are always on shore power, you don't need a lithium battery.  The WFCO in my 2017 charges my 100 ah lithium up to "about" 85 percent.  My solar controller/panel setup can charge it 100 percent.  If I want to, I can use my NOCO smart charger to charge it to 100 percent.  There is no real need to replace the WFCO.

stepheng

I looked at the 2016 T@B wiring diagram and it looks like I could disconnect the WFCO charger from supply side of the 30A fuse and hardwire the Victron IP22 as a replacement.  Has anyone done this?

stepheng

Can't find schematic of WFCO that shows the internal circuitry - not sure the charger circuit is separate from the converter circuit.  Anybody know or have internal schematic?

techietab

I'm also curious about this as well @stepheng. For the moment my LiFePO4 battery array is still connected to the WFCO and my IP22. I just keep the battery disconnect switch in the 'off' position when I am running on shore power. 

Maple_Geek

I was lucky enough to get the WFCO with the Lithium dip switch in my 2022 T@B 320S so for me my lithium battery gets charged to 100% when I'm on shore power. The settings on the Victron solar controller can also bring the battery to 100% when on solar.

I just bought a 2nd LiFePO4 battery (total 200Ah) so now I need to figure out a box for the set

cafyrman

If I recall, the 320 batteries are in the tub on the tongue, correct?

So, no actual box would be necessary, especially with lithiums.  I'd look to the off roading world.  Something like: https://barnes4wd.com/products/barnes-4wd-dual-odyssey-pc1500-group-34-78-group-24-battery-box  Using tamper proof Torx would help somewhat with theft protection.

Maple_Geek

@cafyrman correct that they are by default in the front tub but that still leaves the battery contacts exposed. I store 1lb propane tanks a small hatchet in the tub so potentially things that could short batteries. For that reason, I want them enclosed in "something" which I haven't figured out yet. I'm also interested in looking into reducing the propane tank from 20 lbs to 10 lbs to reduce the weight and increase space in the tub.

stepheng

The WFCO 8735 has a 30A fuse for the charger circuit going to the battery. This means that there must be separate converter and charging circuitry in the unit.  When on shore power the converter will supply voltage to the 6 DC circuits but disconnect the battery from them and only supply charging voltage to the battery as required (bulk, absorption, float, etc).  When disconnected from shore power the battery must be connected to these 6 DC circuits to power them.  This means there is a relay (physical or solid state) that disconnects the battery from the DC circuits when on shore power and re-connects them when no shore power is present.

Anybody looked inside one of these units and determined how this works or have an internal schematic?

Ideally we could disconnect the internal charger of the WFCO 8735 and externally install a Victron IP22 in its place to charge the battery when on shore power and use the WFCO to reconnect the battery when no shore power present.

Denny16

Just use a A/B/Both battery switch between battery and WFCO connection and your Victron Charger, or simply just turn the existing battery switch off, when on shore power, and the WFCO will power the trailer and not the battery.  When not on shore power, just turn the battery switch back on to get 12VDC power to the trailer.  I do this to keep from overcharging the battery durning long stays at home base, whilst the TaB is not in use.
 Cheers