Upgrading starter battery/converter, add inverter?

Ceci

We’re about to close on a 2021 320 boondock. The dealer has said that there is no inverter in the unit. There is a small lead acid interstate battery (I don’t know how many ah)

I already have a Vmax AGM deep cycle 155ah battery and a 1000w inverter.  But it’s 90 pounds and 13.5 x 6.8 x 11.3 inches. Is this too big for the front box and/or much for the tongue weight? (Towing with a tundra) 

How can I use what I’ve already got and not break the bank? (Light duty office work  with laptops, cell phone signal booster while boondocking)

Get a new converter? 

Or just put the battery under the passenger seating platform, get a Victron charger and simply use it as a self contained unit. 

Can I get a new converter that is savvy enough to charge AGM and eventually lithium when I ever upgrade? 

Thx so much for any advice! 

VictoriaP

The current converter does just fine with AGM, no need to change it for that. And your tongue weight limit with a Tundra should also be fine. Ask the dealer for measurements to make sure your big battery will fit and you should be in business.

ScottG

Worse case you may need to change out the battery box for a bigger one. I did this on my 2015, and the tubs on those were smaller.

pthomas745

For the light duty work you are describing, you don't need a big inverter.  The small inverters that plug into the 12v sockets inside the trailer are quite useful.  I use a 300 watt simple inverter, but never get close to that wattage.  The USB/12v plugs are on a 15 amp circuit, so it will keep you honest. I run laptops/battery charging, etc.  in this way all the time, with just a stock battery and a 100 watt solar panel.  With your bigger battery, this would be an easy thing to manage.

Even better would be to find the 12v adapter for your laptop.  A bit more efficient.

Some owners "back in the olden days" added inverters into their 320's by wiring them directly to the battery, which gave them more flexibility on power use.  Here is one thread, one other owner managed to wire it to the cabinet under the driver's side bench.

https://tab-rv.vanillacommunity.com/discussion/7945/320-hidden-location-for-a-2000w-inverter

Denny16

You want to size an inverter so it is running at 70-80% of its max rating to get optimal conversion with minimal loss.  So it you had a 150watt load, a hair dryer, and you are not trying to run a microwave, than a 200 watt inverter is as big an inverter to use.  Work,out what your max load will be and size accordingly.  It running a computer you may want to consider a sine-wave inverter.
cheers

Ceci

If I’m understanding everyone, the current converter will charge up my 150Ah battery good enough. (Will it be slow? Vmax recommends Something like 14.4 volts. ) 
if that’s the case, I could plug a little cigarette lighter pure sine wave inverter into the 12 volt ports and that would run my computers. 

That would be easy peezy. 

pthomas745

"Slow" depends on how low the battery has been discharged.  The lower the battery is depleted, the longer it will take to recharge it.

For your power needs, you need to consider the amp hour needs of your fridge.  The newer fridges are more efficient, but most likely it will be your biggest power user.  Another reason to go with your bigger battery.

Sharon_is_SAM

@Ceci - we have a 150Ah 96# battery battery and it charges just fine.  The issue with the converter and AGM batteries is the length of time it spends in bulk or absorption.  At any rate, according to my Victron battery monitor, it gets charged to 100%.  Just to be on the safe side, before storing in between trips or for the season, I charge it with a smart charger.  No problems with tongue weight either, although we don’t carry the spare on the tongue.

If plugged in somewhere, you can always turn off the battery switch and connect a smart charger if you feel the need to speed things up.

DougH

@Ceci ; What everyone said about the converter. And yup you should be able to use your existing stuff without having to buy anything except maybe battery cables and a fuse, if you dont still have those.

And tongue weight will be fine with the Tundra as long as you don't put a whole lot more up on the tongue. I used new steel rails to put a VMAX SLR125 Group 31 into the front tub, and welded them to the existing rails, since I didn't want the bigger tray simply perched on top the stock Group 24 sized rails, or held in place only with gravity and a battery box strap. Plenty of room. Your VMax 155Ah is nearly the same size width and length as my 70# SLR125, but it's 2-3" taller, and 20# more. Use appropriate size (6AWG or thicker) cables to connect battery to inverter, depending on how far you need to run those lines to whatever well ventilated place you put the inverter.

 
 
 

Or as mentioned, use much smaller sine wave inverters in the existing 12V adapters in the cabin for the laptop, etc.  Is your existing inverter pure sign wave?

Ceci

Thank you for the specifics. This is great info! Yes, I have a pure sine wave inverter.