Three Batteries in a 2019 TAB400?

JeffroNC

Has anyone put three batteries in place of the two golf cart units in a 2019 TAB 400? I am going to replace the original batteries now that LifePo batteries are cheaper. Here is one I am considering. It is 8.5” tall and 13”L x7”W.

pthomas745

Some people have managed to get dual batteries in the driver's side, and there have been mentions of batteries on the passenger side.  Pictures are hard to come by, though, but this thread has a couple of pictures of dual lithiums on the driver's side.

https://tab-rv.vanillacommunity.com/discussion/10627/solar-battery-upgrade/p1

I bought the same battery a couple of months ago to replace the 5 year old 320 battery.  The price was right, at least.  I'm a Will Prowse fan, and his review was positive.  The only caution was about this battery's management system doesn't have a "low temperature charging" cutoff.  I don't often encounter freezing temps, so that was not a deal breaker for me.  Just something to think about.  (Inside your trailer, that shouldn't be as much of an issue.)

https://tab-rv.vanillacommunity.com/discussion/10627/solar-battery-upgrade/p1

The other threads with multiple batteries involve owners who are working on using the air conditioner on 12V power.  Here is one such thread.  An owner in the thread built his own lithium battery banks which probably helps with the fit.  (Another Will Prowse area of expertise:  build your own lithium!)

https://tab-rv.vanillacommunity.com/discussion/14637/battery-inverter-charger-upgrade#latest

RFraer

 

I put 3 SOK 208AH Lithium in my 400. There was only 10 lbs difference between the 2 AGM & 3 Lithium batteries. I did not use the original AGM battery box. My battery box was attached to the floor and under the bed side supports to take some load off the floor. I suggest any method you come up with to secure the batteries should not put the battery dirrectly on the floor. You should also consider a charger that supports Lithium and a battery monitor to see state of charge. May also need to change fuse and wire gauge.

Denny16

OK, the original dual 6-VDC batteries in a 2019 TaB400 are under the passenger side of the rear bunk.  The examples shown in JeffNC’s first post are later TaB 400 (2020-2021) when nüCamp moved the batteries to the back of the rear center compartment.  The 2018/2019 TaB 400 has a supported false floor under the under bunk storage area, where the plumbing snd wiring runs are located.  See photo below of 2018/2019 TaB 400 rear area under construction:

Note the two short bits of 2x2 next to the water pipes in the photo above.  This is where the battery is installed and the 2x2s giving added required support for the heavy batter/batteries.  The floor thst covers this area is a 1/2-inch plywood panel that is only supported at the edges, and the two battery support blocks. 

You can put two of these batteries where the original two AGMs are (enclosed in the black box under the right side of the bunk) where the original single 12VDC battery was located, as shown below:


The false floor is installed here over trailer floor covering the plumbing and wires under it, and the 2x2s added, are under the battery area to support the battery’s weight.  The rest of the floor area is hollow under it and unsupported until it connects to the Alde compartment divider (see top photo).  

This storage area was designed for light weight materials, like clothing and bedding.  Adding more than 20-lbs per square foot of load, or around 150-200 lbs total spread out over this area, could cause the floor to sag.  Keep heavy items towards the edges where the floor is supported is also a good idea.

The floor area next to the original battery area could be used for a third 100 amp LiPro battery.  But, if you want to add two or more batteries here, you will need to pull the false floor up, and add more 2x2 support blocks, then screw the floor area to these blocks to create the required support.  

This was the recommendation I got from our dealer’s factory trained TaB technician, when I inquired about replacing the original AGM with Lithium.  I was advised not to try and locate them to the rear center area, without adding more floor support.
cheers

RMo

Your comments on floor design and weight caught my attention @Denny16 as I have a 95lb battery, an inverter and a charger all mounted on a platform in the center underbed compartment of my 2019.  Is the issue that the false floor may sag with too much weight?  If so, what problems could this cause?  Did the the tech provide any info or do you have thoughts on why some sag would be a problem?  I haven’t noticed any but to be honest I haven’t looked.   Thanks.

Denny16

Yes @RMo, I think worst case is a bit of sag of the false plywood floor panel towards the unsupported center, that is only supported at its edges, and is only around 12mm +/- thick.  This came up with the tech, as the previous owner of our 2018 TaB400 had replaced the original 220 amp nüCamp AGM battery with a slightly larger 200 AGM Interstate battery, and put it in the center area next to the Alde partition, so it was supported on one edge, but the center was bowing down some from the weight towards the unsupported side of the battery.  This also stresses the edge fasteners, as the blowing down in the center, becomes a lifting force on the edges.

He recommended putting the battery back in its nüCamp designed location, which he managed to do with a small modification to the end cover.  I did not have the later added black enclosure around the battery, nor the little battery distribution box.  This move restored the weight distribution in the TaB, so the battery balances out the weight in the Alde compartment.  

His recommendation to add underfloor support running from front to back, would not only prevent the floor panel from sagging, it would also transfer some of the load to the trailer’s floor frame cross members.  He also added, the more weight you put into the rear (behind axle) area, the more you change the trailer’s front to back balance and tongue weight.  You do need to maintain a minimum of 10% total trailer loaded weight on the tongue, which is 300 lbs minimum on a TaB400.
cheers

JeffroNC

Thanks for the great replies. Lots of stuff to think about. I was already thinking about moving the much lighter LifePo batteries further back than the original to help with balance. I will be doing the swap in March so I will let you know how it turns out. I might start with two batteries. The would still be twice the AH that I have now with the AGMs.

JeffroNC

Two of the Ampere time batteries fit without the cover. I’m going to see how well they work tonight. Don’t look at our TP stash from the pandemonium days.   

Dutch061

Here is what my 4 BB's look like. 



Brad

JeffroNC

Nice work. You could jump start a jet engine with that setup. 

kottum

Brad, nice clean install.  We have a T@b 400 on oder with two BB's installed by dealer.  What size cable do you have connecting the batteries to each other.  I understand they should be of sufficient size that the battery bank acts as one battery, virtually no resistance between them.

Dutch061

Thanks, I used 2/0 for everything up to the junction block. I bought the cable, lugs, crimping tool, and shrink tubing so I could make the cables. With 4 BB's, I can have up to 800 Amps for 30 seconds and 400 Amps continuously. I have never gone over 90 to my knowledge and that is only while I am using the inverter.

It is cleaned up more since this photo in November 2020, I have replaced the PD9260CV converter shown in the photo with a PD9160ALV, and I have moved the display for the BMV-712 into the cabinetry above the air conditioning controls. I used 4-gauge cables to connect the converter to the battery junction block, which allows me to have a full 60 amps input to charge batteries. We boondock almost exclusively and being able to recharge quickly and easily when necessary is important too. 

I have also added a fuse block, relays, wiring, and switches to control the heating pads I installed in January. Still need to write that project up, most difficult part was cutting the insulation that was used to line the inside of the frame. 

Brad

JeffroNC

Update:
To date I have replaced the factory converter with a Progressive Dynamics unit that is Lithium ready. I installed a Victron DCDC charger in my truck and added 8AWG wiring with a connector on the bumper. I eliminated the 12 volt circuit on the 7 way connector and wired 8 AWG to the junction box on the front of the tab. I also have a Victron BMV.

With the two LifePO batteries installed and charged, I unplugged from shore power. As an acid test, I ran my inside AC/DC fridge, truck fridge, lights, entertainment stuff, the Alde, and my CPAP with humidifier and heated hose.
In 24 hours, I used 80ah of power! I know how to use a lot less so this was a test.

I plugged in to shore power and with my PD converter switched to lithium, it charged at 45 amps. In two hours, the batteries were at 100%.
I think that I will be able to boondock and only need to run my generator for a couple hours every few days. (Unless we are out west getting awesome solar like we did a couple years ago.)  If we are moving sites, my truck charges at 15 amps now with the DCDC converter with another 5-10 amps from solar. The batteries should recover a good bit between locations.

I’m happy with the results. I have room for one or two more batteries but I don’t see the need. YMMV

I understand that I could have done a more technically correct job with this. The following items could have been done better. 
I used 8ga wire instead of 4ga. ($$$)
I used the truck chassis for the ground instead of running a second wire.
I mounted the DCDC charger in the truck, far from the batteries.
I used the TAB wiring from the junction box back instead of drilling a hole and running new 4ga wires.

Yes, there is voltage drop. The wiring to the junction block from the converter got slightly warm after an hour at 45 amps. But I am cheap, lazy, and have not had a good place to work on these projects in the last few months due to moving. 

One thing to note is that the BMS in the batteries just stops charging when the batteries are full. One minute there is current flowing, the next minute there is none. There also doesn’t seem to be a ramp in current like with lead battery charging. As I understand it, the “charger” is actually in the batteries, the external chargers pretty much apply current at a controlled voltage.

Being able to boondock comfortably for several days is great and opens up a lot more Harvest Host, Boondockers Welcome, and Hipcamp opportunities in locations and times when AC is not needed.

Happy Tabbing!

AnOldUR

JeffroNC said:

I plugged in to shore power and with my PD converter switched to lithium, it charged at 45 amps. In two hours, the batteries were at 100%.

Can someone educate me on this? How can a battery be charging at 45 amps when, at best you're plugged into a 30 amp service? What if your using a dog bone adapter and getting 15 or 20 amps? Is it something about wattage being consistent but voltage going from 120V to 12V?

CrabTab

@AnOldUR Total electrical power is measured in Watts (Volts x Amps). It is a ratio. 120V x 30A equals 3,600W. At 12V the same amount of power would be 300A. So, 45A at 12V is not pulling all the potential power from the 120V circuit.

JeffroNC

^^ what he said. 😎

AnOldUR

So the 900 watts that my little Baja generator can put out at 120V has the potential to provide up to 75 amps to charge my 12V batteries under ideal conditions (which don't exist)? 

Dutch061

The rate at which you can safely charge your batteries falls back on the battery chemistry and amount of Amp Hours. My PD9160ALV draws right at 13 Amps (13x120=1560 Watts), so I am going to say NO. Especially if you are using the OEM Converter in the WFCO PDC.

Brad

JeffroNC

I wish I had my kilovolt tester with me so I could measure the shore power use. It will be a couple of months until I can do that. 

I am currently mooch docking on a 15 amp connection at our kids house. 

JeffroNC

@Dutch061 I am leaving my Tab at my kids house in the NC mountains where it will probably freeze a few more times before we get back. My new LifePO batteries don’t have cold temperature cutoff so I am thinking I need to pull the fuse on the solar while we are gone to prevent charging. Does this make sense?
Its not an issue when we are in the unit as we obviously keep it above freezing.

pthomas745

If you have the Victron controller, in the battery setting section, there is a "Charging" toggle switch.  You can turn "charging off" on that setting. This is the comment from the Victron controller manual.

Charger enabled

This setting Enables or disables the battery charger. It is by default set to "enabled".

This setting can be used when work needs to be carried out on the installation. When this setting is disabled, the batteries will not be charged.

JeffroNC

@pthomas745 thanks!

Dutch061

Th alternative is to add a $30 temperature sensor to your batteries. Then within the settings for the Solar Charge Controller, you can specify a temperature to disable charging. I failed to mention that this must be used with a Victron Shunt, either a Smart Shunt or a BMV-712. The MPPT doesn't have the ability to receive the data outside of a networked shunt. 

With that said, Battleborn recommends that for storage that all devices are turned off and that any charging is also turned off. So, turn the Perko off and disable the solar charging by turning it off as @pthomas745 said.

Brad

JeffroNC

@Dutch061 thanks. I will look into that when I get back to the camper in May. For now, the fuse is out and the switch is off.

Dona

@RFraer  you said   “I put 3 SOK 208AH Lithium in my 400. There was only 10 lbs difference between the 2 AGM & 3 Lithium batteries. I did not use the original AGM battery box. My battery box was attached to the floor and under the bed side supports to take some load off the floor. I suggest any method you come up with to secure the batteries should not put the battery dirrectly on the floor. You should also consider a charger that supports Lithium and a battery monitor to see state of charge. May also need to change fuse and wire gauge.”

I’m wanting to install 2 lithiums under the black box in the 2019 tab 400 (no solar)..  It sounds like a pain. I’m thinking of having an rv place do the work, but I’m wondering if I should remove the cover first to save myself a ton of dough. I read it could take over an hour. And, I would see how the lithium will fill the space.  And I’d be prepared for a discussion about supports that I might need  to add to hold them in place. Then I have to decide to recover them or not... any crazy thoughts to go with mine?.

Horigan

The cover isn't required for a lithium battery.  It's there to collect the potential hydrogen gas outgassing of the AGM battery during charging, which isn't an issue with lithium.  Without the cover you have more flexibility on how to support/restrain the Li batteries.

Denny16

The space under the bunk on the 2018/2019 TaB400 is reinforced under the false floor with 2x2 bracing over the trailers sub floor/frame.  So it should not have an issue holding two lithium 100 amp batteries.  

As Horigan mentioned, you do not need the black cover, it is not holding the battery in place, just covering it up and collecting any gas to vent outside. The original 2018 TaB400 battery install did not have the black cover/box unit.  It used two 1x1 bits of wood screwed to the floor against the battery on its side and ends to secure it in place.  

This is how the heavy (200lbs 200amp AGM battery in our TaB400 is secured.  Bed framing is on top of battery, and it has not moved in 4,000+ miles of driving in rural and dirt roads.
Here is a photo of battery area on the original TaB400s:

Red arrow shows 1x1 framing on floor.  Bed support 2x4 rail on top of battery.
To get the battery out is not an easy task, you need to remove the bed area above the battery, pull the floor framing supports and slide the battery out towards the center area.  

Cheers 

Dona

@Horigan and @Denny16 thanks so much for your replies, and especially the photos and instruction about what to disassemble!!

Denny16

You are welcome Dona.
 Cheers