Battery Separator Question paralleling Inverter Install

[dtcerrato]

only the charging part of the converter

That's the only portion of the deck mount converter that I have. So I'll just delete it from the house bank that it's charging.

@ Dave
10-4 on the equalization charge.

@ Thomasinnv
I like the Magnum me-sbc with an external 500 amp relay. I may go that way instead of the Blue Sea battery separator. I like the 25 amp charge to the start batteries & the optional 500 amp solenoid although I may miss the manual override in the Blue Sea unit.

@ BW
I am the other peep! Heck when we did the initial conversion on our in service 04 back in 79 it was me & only me - ya know the dark age. No internet. We had two bat banks from the start, had to because it was a pos ground chassis till recently. Never wanted to touch the start bats with anything but the starter. I just hate to waste the added resource of two 8D deep cycle/start batteries sitting there just for the starter with a brand new inverter on board!

Thanks all, we're wrestling this one to the ground besides it's great during social isolation. Nothing like being on world news everyday here in sunny hot & humid Florida. One thing we have learned... covid doesn't know what heat & humidity is! Stay well...

[thomasinnv]

@ Thomasinnv
I like the Magnum me-sbc with an external 500 amp relay. I may go that way instead of the Blue Sea battery separator. I like the 25 amp charge to the start batteries & the optional 500 amp solenoid although I may miss the manual override in the Blue Sea unit.

You could easily wire in a remote manual switch to the 500a relay. If you do go that route, don't get the cheap junk relay, get the biggest heavy duty one you can find. The one I use is called a "big boy" and is rated somewhere around 1200a contact surge and 500a continuous. The 250a I started with lasted about a week. The problem is if you are drawing a heavy load or batteries are deeply discharged when the relay engages causing the contacts to arc. In this case bigger IS better.

[someguy]

Tesla Model S/X batteries sell for ~$1100 and have 5.2 KWHr of usable storage, for many thousands of cycles.  They are also 24V.  They weigh about 58 pounds each.

They are finicky to use.  1) You can't over charge them, voltage wise.  2) You can't discharge them too far.  3) They need to be temperature controlled for big draws and/or charging below zero.  Tesla cars have all the circuitry and equipment to handle this stuff.  Some RV components can be set up to do this too.

My ultimate system would be:

- 1500 watts of solar on the roof.   That costs a bit over $1000 these days.
- a big alternator(s) on the coach engine (200A+)
- 2 Tesla Model S batteries
- no coach battery
- 2 3,000 watt 24V inverter/ solar/ AC chargers.  Not sure I would actually need 2 of them.  (https://www.ebay.com/itm/Solar-Inverter-Hybrid-3Kva-2400W-Off-Grid-Inverter-24V-120V-80A-MPPT-Charger/133479473890?hash=item1f13ff22e2:g:dRQAAOSwtPJfIpIh)

- mini split A/Cs.  FWIW, most mini splits have a much higher SEER (BTU/watt) than the RV rooftop models.   
A predator 3500 watt gas inverter generator.

The first rule when trying to run from batteries is to conserve energy so you need the least amount of battery.   A Coleman Mach15 is rated at 15000 BTU and pulls 14.8A @ 120V.  It has a SEER of 8.45.   Mini splits have a SEER of around 20.

The other thing is that rooftop ACs are sitting in the hottest place possible - up on the roof.  With a mini split at least you can put it in the shade.  And if water is available, mist the condenser, which makes a huge difference in performance.

Yes, the Tesla batteries will easily start the coach. 10 KWHr @ 24V = 416 AH.  At 3C discharge, that is 1200A.  They'll do it better than a FLA because of less voltage drop.

At first 10.4 KWHr doesn't sound like a lot of energy, maybe 8 golf cart batteries or so.   

But there are 3 really big differences:
1) All 10.4 KWHr is usable, not like flooded lead acids that should only be drained to 50%.
2) There is very little Peukert effect.  This is voltage drop due to current draw. FLAs are terrible for this.
3) I forgot what the 3rd advantage was.

If we are using mini splits with a SEER of 20, 1.5 KW of solar gives us 30,000 BTU of A/C.
A 10.4 KW battery pack will run 1.5KW of A/C for ~6 hours without running the generator or having any solar at all.  Throw in some solar or judicious generator use or even a 15 or 20A shore power and lots of things become possible.

A 200A alternator on the engine will produce 200A x 24V = 4.8 KW.   With a good mini split system that is an awful lot of A/C for OTR cooling.

My goal with all this is to
- run a genny as little as possible
- keep the weight of the system down
- have good OTR cooling
- keep things simple.
- keep the cost down.

I've had 480 Watts of solar + 2 KW Inverter + 6 GCBs on my 5th wheel for the last 10 years.  I'm done with GCBs.  When the batteries are new with solar helping, this will run a 13,500 BTU A/C for a couple hours.  It also runs the microwave well.

When not needing A/C, 480Watts of solar does a tremendous job.   The batteries are almost always topped up by noon. LED lights really help.

If I need to run a generator, I'd like it to be an inverter model and I want to place it in the shade behind a bush 30 feet away from the coach, so I don't hear it and hopefully neither do the neighbors.  I'd also set it up so it could be run from the bay.

The good thing about having a 10.4 KWHr battery pack is that I wouldn't need to run the generator all the time and I could be selective about when I do run it.   And I wouldn't have to run it at full output.  The larger 3KW+ inverter generators are very quiet at sub 2 KW loads because they are still idling.  With dual inverter/charger units, I could be connected to 15A shore power with one inverter and power the other with a generator running at half power.  Throw in some solar and it is possible to be charging batteries while running the AC.

The inverter units I linked will run in parallel, including charging the batteries in parallel.  If connected to 15A shore power, one inverter can be charging the battery pack from AC while the second unit is charging it with solar, while supplying power to the mini split(s)

Thoughts ?

The manual for the charger is here: https://www.mobile-solarpower.com/uploads/1/2/9/6/12964626/pip-lv_3kva_manual-20160823_3.pdf