Battery space in 400?
kbdigitiqe
Member Posts: 163
Hey y’all, we love our 320 but just got a second pup and almost certainly will need to up size to the 400 for next season.
I did an Li battery upgrade on our 320 and will definitely only be Li from here on out. This time though I’d like to get to 300-400ah as we pretty much only Boondock.
Tried searching without much luck, can anyone point me to some info / threads on the battery compartment in the 2021 400 so I can see what’s possible?
To clarify further, it seems like I could def drop in two of the BB 100ah models that are shaped like the 6v AGM but curious if I can do more. Thanks!
Comments
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The battery compartment in under the rear bunk at the back of,the center area, similar to this:

You could add extra Lithium batteries in the front of this area, as long as the weight does not exceed the floor loading limits.
cheers2018 TaB400 Custom Boondock, Jeep Gladiator truck, Northern California Coast. -
@kbdigitiqe we need to see a picture of your new pup! ps. Battle Born has a sale going on now...Debbie in Oregon
Sold 2023 Tab 400
Sold 2018 T@B 320S -
@Denny16 - other than loss of space, any reason to not use the passenger side storage hatch area for a battery install?Sharon / 2017 T@B CSS / 2015 Toyota Sienna Minivan / Westlake, Ohio
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You could add a Lithium in the side storage area, against the divider partition, but not in the back. You need to keep,the batteries close to keep the connection cables in the AWG 4 size range. Longer cable, would require bigger cables, and this gets awkward to route them.The large center area under the bunk has a lid that lifts up. The battery area is under a screw down panel. You would need to remove both the center area panels and the pax side storage panel to work in the area and gain access to the batteries and wiring. Not hard, just four screws per panel.
cheers2018 TaB400 Custom Boondock, Jeep Gladiator truck, Northern California Coast. -
If you are handy with wood, it seems it would be pretty easy to move the front battery compartment wall forward and make room for two additional batteries where all four would be in the larger space and close together for wiring purposes.2019 T@B 400 Boondock Lite
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The existing batteries are located over an aluminum frame cross member. You need to reinforce the floor in between frame members before adding more battery weight. The 2018/2019 Tab battery was originally located in the storage compartment on a false floor that was braced. You would need to do something similar.I would contact nüCamp before adding additional batteries, and get a suggestion as to where best to place them. You need to watch the floor loading, as batteries exert more load per square inch than normal camping type cargo.
cheers2018 TaB400 Custom Boondock, Jeep Gladiator truck, Northern California Coast. -
@Denny16 is the floor loading concern still a problem with 30# lithiums?Debbie in Oregon
Sold 2023 Tab 400
Sold 2018 T@B 320S -
That depends on the weight per square inch, and is a question best addressed to nüCamp customer service.Cheers2018 TaB400 Custom Boondock, Jeep Gladiator truck, Northern California Coast.
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I’m not really concerned about weight as the Li are so much lighter than the regular batteries. I am concerned about accessing the batteries though as I don’t plan to swap out the inverter so I’ll need to charge them up with a regular Li charger before each trip like I do now with our 320. I wonder if I can just add a nice looking access panel near the battery compartment or if it’s too far back?
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If you are referring to replacing the AGM batteries with Lithium, that would work.
Adding the Lithium batteries in front of the existing AGM batteries in the storage area depends on the mass of the battery (weight per square inch of the surface area of the battery) not its total weight.The center rear storage compartment shown above in front of the battery box (under the bunk) has a lift up cover already.
cheers2018 TaB400 Custom Boondock, Jeep Gladiator truck, Northern California Coast. -
@Denny16 that's compelling actually! because if the two new Li's sat in the compartment that opened and they were tied to (two more Li's in) the original location in parallel, then I could hook the charger up to the the posts that were more easily accessed. Thanks!
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@Denny16 do you happen to know the usable height of the storage/battery compartment in your pic above?
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Sorry no, but it is deep enough for a 200 what hour AGM batrery that is around 7.5 inches high, and the battery space in our 2018 TaB400 has 9.5 inches of height in the battery space, (edit: just measured it). My 2018 TaB has the false floor, the 2021 model eliminates the false floor, putting the plumbing and wires in the false panel between the storage compartment and the front bunk panel shown in the bottom of the photo I posted above.
cheers2018 TaB400 Custom Boondock, Jeep Gladiator truck, Northern California Coast. -
Ahh ok that’s great thanks!
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@kbdigitiqe, the note below is from Nucamp support sent to me the other day regarding the 2021 T@B400, I'm swapping out my batteries as well:
"The available battery area in the battery compartment is about 20"L x 7.5"W x 11"D.
The battery compartment itself is 25"L x 7.5"W x 11"D total but some of the area is taken up by the vent hose. Some of that space could probably be reclaimed by removing the vent hose"2021 T@B 400, 2020 Audi Q5
Portland, OR -
Oh man my Renogy 170ah from my Tab320s is 10.6” tall.. gonna be close.. eeek! But I want to try to use it before I go full blast on x4 100ah BB’s
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No worries, you have 0.4 inches of clearance.Cheers2018 TaB400 Custom Boondock, Jeep Gladiator truck, Northern California Coast.
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Another issue, if I swap the 2 AGM batteries 130lbs with 1 battle born battery 30lbs this will increase my tongue weight by 100lbs(2021 T@B400). Do you guys agree?2021 T@B 400, 2020 Audi Q5
Portland, OR -
No. Measure the distance from the battery to the axle. Also measure the distance from the axle to the tongue. Divide the first number by the second and multiply the delta weight (100 lbs). That will approximate the tongue load increase (probably more like 20 lbs).Rich2019 T@b 400
2025 Toyota Highlander 2.4L TurboBellingham WA -
@Polanskyster you are not gaining any increase in available DC power by just adding one 100 amp BB lithium battery, you need to add two 100 amp batteries, (or go with a 140 amp lithium battery) to gain the extra 40 to 80 amp hrs of power. Otherwise you should just keep your two AGM batteries (which gives you around 140 amphrs), and upgrade to 200 amps of Lithium when they need replacement. This is what we are doing, not broke, why fix it?
You do not need to reduce weight in the rear at this point, and the heavier AGM batteries work to reduce your tongue weight. A lithium upgrade to 200 or 300 amps would be around the same weight, and form factor, and give you more DC energy to use.2018 TaB400 Custom Boondock, Jeep Gladiator truck, Northern California Coast. -
Ehhhh @Denny16 ya tripped me up! Does the 400 come w batteries installed at the factory? Or is it like the 320 where my dealer just dropped one in?
if so what are the batteries it comes with? -
@Denny16 I was thinking of getting 1 for now then another next year after using the advertised benefits of lithium, quick solar recharging etc. However after reading your insightful comment and the tongue weight issue I will be getting 2 100 amp Lithium batteries, thanks. This year I plan to do a lot of boondocking.
@kbdigitiqe the 400's(2021 Boondock) come with 2 AGM 6v 224ah batteries.2021 T@B 400, 2020 Audi Q5
Portland, OR -
Ugh.. now the numbers are close enough that I’m thinking about using my Renogy 170ah Li and getting a second one to put in parallel so it’s worth the effort 🤦♂️
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Fair enough everyone, should work. @kbdigitiqe, the TaB 400 comes with two 6 volt AGM batteries in series, giving you around 220 amp hours.
cheers2018 TaB400 Custom Boondock, Jeep Gladiator truck, Northern California Coast. -
@Denny16 I can’t find a post from a while back that mentioned a “battery wire junction box” or something like that. Do you know if there’s a pic somewhere of that box and it’s location?
I’m trying to understand how I’ll use my outboard Li charger to top up before each trip and hoping it doesn’t involve having to access the entire battery compartment?? -
If you get a 2021 TaB 400, there is a SAE plug that is wired to the battery, you could use it to connect an external battery charger. The battery junction box is between the battery compartment and the passenger side storage compartment under the rear bunk. Access requires removing the top bunk base plywood.
cheers2018 TaB400 Custom Boondock, Jeep Gladiator truck, Northern California Coast. -
ahh ok thanks!
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I noticed there is contradicting info above on how many amp hours the two 6 volt AGM batteries produce. One thread said around 140 amps the other 220 amps. Can anyone clarify for me.
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2 6V give you 220aH
2021 TaB 320 Boondock, Gran Cherokee TrailHawk
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