[Nebster]

Thank you, Nebster (I’m sure you have a real name) - this is a great article and is something I would love to do as I am currently watching carefully as my battery bank is dying.  Did this bank replace your engine start batteries?  

Hi Adrian,

I decided to keep the engine start batteries.  The main reason for doing that is because it is hard to get 12V out of a 52V pack, and doing so would require me to add another discharge source onto the lithium bank.  I wanted only one discharge source to make it easier to ensure the pack will never be fully discharged.  If the pack ever gets too low, I need only shut down that one Victron inverter, and that removes all loads from the pack.

The other reason to keep the engine batteries around is that removing them doesn't gain me much -- they are in a different place that would be hard to use for something else productive.  Keeping them on board has little downside in terms of storage space, and reclaiming that space wouldn't give me more room for more lithium, really.

The final reason to keep them around is that they provide a degree of redundancy.  Even if the lithium bank has a major problem one day, I know that I can still start the engines, which means I can generate power that way and I can drive somewhere.

Which bay did you end up mounting this in?  

The batteries are in the regular battery bay.  You can see I reused the original Newell tray if you look closely at that picture.  I did have to modify it a little bit to give me an extra inch of vertical clearance on the bottom tray.  Your batteries will, no doubt, be different, so YMMV.

Should I do solar panels and a decent charge controller/monitor first or batteries first? 

Batteries are a much bigger leap, both in cost and complexity.  Solar makes a lot of sense if you enjoy boondocking in places where you don't otherwise need much air-conditioning, because with care you can then avoid even running the generator.  You really have to do the power budgeting, though, to figure out what your cost-benefit tradeoff will look like.  One problem with Newells is that we tend to have all the nice things onboard, which means we tend to use a lot more power than other motorhomes.  Your ability to reign that in will likely determine whether solar-only makes sense.

It is obviously a huge luxury to be able to run everything, whenever, even for days at a time, without having to plug in or have the genset spun up.  Also, the ability to use the big battery to do demand shifting lets us camp in places with 30A or 20A circuits while living like we are on a 50A/240V circuit.

Keep me posted as you make your decisions!