Lithium battery upgrade on 17B

[dosby]

I got 100Ah GoPower battery from ETI as part of their full lithium package, and it serves the basic needs, but I would like more flexibility with non-hookup camping. Water supply is usually not a big deal and can be solved by a 100-150ft collapsible hose. Drainage issue is partially solved by washing dishes/hands/kids outside. However, we did deplete the battery completely a couple of times when camping in a shade and using microwave/instant pot. Trying to avoid non-hookup sites since then. I know that portable solar could help recharge but not in a shade or a completely forested campground.
What I am thinking is that adding a 300Ah battery could help us last 3-4 days. A single 300Ah battery, to avoid complex wiring. And it's not heavy enough to break my back, ~55-65 lb.
The only place to install it is under the passenger (right) side bench. We have an exterior hatch, for mostly lighter smaller things like levelers, etc. A grill won't fit, not even a front box. All in all, I am ready to sacrifice some interior space. Driver side space is mostly full - there is a water heater tank, electrical stuff, water pump, etc.

I have found a few 300Ah choices online - most of them are ~21" * 10" * 10". There are a few that are 15" * 7" * 9" and would fit the space better but those don't have much customer reviews and seemed to be made via some "pouch" technology (totally legit, just not as tested in RVs). Example - https://www.amazon.com/dp/B0CX1DGZ29
Just 55 lb and smaller than others. What do you all think?

Another question is what to do with the old battery. I read some folks remove it completely, pull the existing wires and reuse them for a new battery. I am thinking maybe keep it as a back up battery? And install some 1-2-OFF 3-way switch? I would probably have to 1-2 switch not just the thick inverter cables but also the 10AWG charging cables, too? And I would need to just keep the backup battery charged, i.e. charge it every few months. Is it worth the hassle?
I know that running 300Ah and 100Ah in parallel would not be a good idea.

The space under the passenger bench has an inverter, but otherwise is empty. Where would you place the new battery? I am thinking either the very back (basically almost directly above the existing battery) or close to the wheelwell (better for weight distribution).

[dosby]

pictures, set 1

[dosby]

pictures, set 2

[dosby]

The space in the back is 19"W but floor space is just 15"W - it would be closer to the existing battery wires. Only the "pouch" battery would fit there, if put lengthwise.
The space near the wheelwell (where the white cap with sanitizer stuff bucket and the red levelers are) is 12"W and ~20"L to the inverter.
So, a perfect size for my new battery would be 12"W, or 15"W, and not very long, but unfortunately, they don't make them square for some reason
There is one, actually - https://www.amazon.com/GuaiGLong-12V.../dp/B0CB12S64R, but it's more $$$

There is also dual-battery route - https://www.amazon.com/ECO-WORTHY-Ba.../dp/B0BJZKC5WN
But 2 of them are 82 lb VS 55 lb for the "pouch" one.

[dosby]

Does anyone know what kind of 12A plugs the inverter uses? If I keep the current battery for backup, I would need to detach the inverter cables from those plugs and connect them to the 1-2-OFF switch. I could not find the way to unplug them but I probably just didn't pull hard enough.

Another idea is to find a new battery that would fit the existing group 27 box. It won't be 300Ah, but maybe 200Ah?
BTW, current 100Ah battery is 36 lbs, 12.9L x 6.8W x 9.2H
Compare to 300Ah, 55 lbs, 13.58"L x 7.48"W x 9.64"H - https://www.amazon.com/dp/B0CXSP94H4

[rubicon327]

Personally I would do one new, high quality battery as big as I could fit and not worry about paralleling an older one. Check out the SOK 280 AH…
https://www.us.sokbattery.com/produc...-and-bluetooth

There is also a 300AH battery from Epoch which is a brand I recently became aware of from forum member viator36
https://www.currentconnected.com/pro...ch-essentials/

This is the 400AH Bestgo that we use that has been great…
https://www.electriccarpartscompany....-battery-packs

[rubicon327]

Originally Posted by dosby

Does anyone know what kind of 12A plugs the inverter uses? If I keep the current battery for backup, I would need to detach the inverter cables from those plugs and connect them to the 1-2-OFF switch. I could not find the way to unplug them but I probably just didn't pull hard enough.

If you are speaking about the DC connections (12 volt (V) not amp (A)) on the inverter you need to remove the red and black plastic terminal covers with two phillips head screws each, slide them down the wire and then the ring terminal connections will be exposed. These can then be removed with a wrench.

[hugh]

I went with the "build them yourself" lithium batteries for my 21C. I built a couple of 460Ah batteries (920Ah total) for around $2150. I haven't looked at recent prices for the cells, but i don't think they've changed that much.

Some more info here:

https://www.escapeforum.org/forums/f...tes-23522.html

[John in Santa Cruz]

I've been very happy with the 2*206AH SOK batteries I installed a couple years ago. 5200 watt*hours usable power. 360 Watt solar panel can fully charge them from a total deep discharge in 2 good days.

[dstreight]

^^^ agree with the '...cry once...pay me now or pay me later' philosophy. All my Victron gear, 10-years+ collecting this/that, has been reliable and worth the extra cost IMHO. Not to mention the network ability with staying in the Victron family of equipment.

[John in Santa Cruz]

The Victron Smart shunt definitely stores at least a week of data internally, you log on with the Bluetooth app and you can graph any 2 factors. . Usually battery voltage and battery current or charge state. When I first got mine, it did not do this, you had to leave the app running to collect data. But a firmware upgrade just a month or two after I got it added that ability.

[dosby]

Originally Posted by John in Santa Cruz

The Victron Smart shunt definitely stores at least a week of data internally, you log on with the Bluetooth app and you can graph any 2 factors. . Usually battery voltage and battery current or charge state. When I first got mine, it did not do this, you had to leave the app running to collect data. But a firmware upgrade just a month or two after I got it added that ability.

good to know they fixed it, thanks!

[dstreight]

This might be unsettling to some...but I did not incorporate a BMS into my LFP battery on our 15A preferring to manually manage current in/out. I am using amperage-voltage balancers and its all worked out perfectly.

[John in Santa Cruz]

I use my trailer enough that there is no such thing as long-term storage. If it's not plugged in (most of the time), the battery will be down to 90% in the morning and 100% by noon if it's sunny, and so far so good. This SOK. Battery has held up quite well