18' Series Expanda Battery Conundrum

Mad_Macs

New Member
Feb 7, 2021
2
2
3
Brisbane, QLD.
So I'm the proud new (well 2nd hand but just acquired) 18.58.2 OB (2018) and she's awesome. Big upgrade from the '06 Freedom poptop. Just starting to take in all the toys and figure out how and what works etc.

My first priority has been 12v because of planned freecamps. So the Setec BMPro stuff is a bit new to me, and I was excited at first, until I dug a bit deeper to find it's a bit more limited than I'd have liked. I'll try to not get too geeky but I've got the J35.B which has limits on solar input, thus limits how big my batteries can be to get a solid charge from solar. The J35.B is capped at <20A and 300W of solar input, which is probably only about half of what I'd like. I believe the C and D revisions did increase, but the stuffing around chasing a 2nd hand unit and reinstalling etc is just too much hassle. (NB : I have noted people are commenting that Jayco have dropped Setec from their 2021 lineup, going to Projecta. I can start to see why)

So I plan to run 2 Waecos (CF40 and CF50) one for freezing, one for 0 degree day to day usage. Have a big 3 way Thetford fridge as well, for "food", but that's not going on the 12v that's either going to be running off the tug while driving, or gas when stationary. So a bit of napkin math (and some actual testing) I've done comes to the following conclusions ;

* Treating the CF40/50 are basically the same for power consumption under 0 and -15degree settings. Doing all the right things, pre-chilling or freezing items put in, using a few ice bricks to add better thermal mass for keeping things cold at night to reduce compressor cycles etc, not opening lid frequently, storing in cool place, in insulated bag etc. They use about 1.1Ah to chill at 0, maybe 2Ah at freeze. That's obviously important for the 18 or so hours of the day you aren't using sun to charge your batteries, or you get crap weather etc.

The factory 100Ah battery and 160W solar ain't gonna cut it. Nor is even max 300W on the BMPro J35.B if I were to just throw up another 160W panel.

I think the solution is, take solar off the BMPro, and get an MPPT charger to support about 600W of panels for 2x150Ah batteries (I'm being generous with allowing 200W of solar per 100AH of battery, I know some people would do less). That just means I can't use the BMPro's info panel for battery usage and that's no biggy. The Bluetooth info on the Victron Smart chargers are more than enough stats.

Only skimming the surface on detail, but anyone else done anything similar, or differently. Happy to hear suggestions. I'm going to the Bay Expo on the weekend to prick some brains, and the 4x4 show is in March, don't want to be shelling $$ out needlessly but not going to cut corners and feel uneasy travelling worrying about capacity and stability of my power setup.

Cheers,
 

Drover

Well-Known Member
Nov 7, 2013
12,723
19,450
113
QLD
The thing is the 300w max is actually meaning 300w not 300w of panels... If you put a stated 300w of panels on the roof you would be lucky to see 300w down the line......
Me I would just divert the solar direct to battery, fit a good MPPT reg (I like the Epever range) and let the J35 just do its thing as a van power distributor and 240 charger, if you run the supply from battery to J35 via the load on the Solar reg it will show you whats being drawn. Epever have a good screen display and a remote display unit, blutooth stuff just means extra stuffing around when a glance at a screen is just needed... of course adding an extra battery, AGM no more than 120ah size else you will get a hernia..............
Also fitting a seperate run for the solar means if the J35 craps out you can simply run the van direct from Reg if you set the wiring up properly in the first place...... My rig is set up so if if one goes I don't loose the lot.
 
  • Like
Reactions: Boots in Action

Boots in Action

Well-Known Member
Mar 13, 2017
2,053
1,804
113
Ferny Grove, Queensland
The thing is the 300w max is actually meaning 300w not 300w of panels... If you put a stated 300w of panels on the roof you would be lucky to see 300w down the line......
Me I would just divert the solar direct to battery, fit a good MPPT reg (I like the Epever range) and let the J35 just do its thing as a van power distributor and 240 charger, if you run the supply from battery to J35 via the load on the Solar reg it will show you whats being drawn. Epever have a good screen display and a remote display unit, blutooth stuff just means extra stuffing around when a glance at a screen is just needed... of course adding an extra battery, AGM no more than 120ah size else you will get a hernia..............
Also fitting a seperate run for the solar means if the J35 craps out you can simply run the van direct from Reg if you set the wiring up properly in the first place...... My rig is set up so if if one goes I don't loose the lot.

Definitely the way to go @Mad_Macs . Forget about putting any solar through the BMPro due to its limitations. Run ALL solar through a good MPPT controller (50 to 60A type) direct to battery/ies. Make sure leads are across the correct terminals when batteries are in parallel to ensure even charging/discharging. If you run all the suitable loads through the MPPT controller LOAD terminals, the Victron will provide you with real time power usage and there will be no need to refer to BMPro display screen for that info or any info really as the MPPT controller can provide all the info you need.

I think that your power consumption figures for the Waecos are way under "real world" figures when tug is in sun and interior is closed/semi closed, and ambient temps outside are around 30C plus. Pre-chilling of cabinets and food is only good for the initial period, but after 24 hours of use, the fridges draw their own demands to maintain the lower temps you need. IMHO.

Perhaps have a look at the link below and see how you compare.

 

Drover

Well-Known Member
Nov 7, 2013
12,723
19,450
113
QLD
Also someone has shown what I thought for ages in that some of these fridge covers actually restrict air flow around the heat exchange parts, making them work harder, just a thought.
 
  • Like
Reactions: Boots in Action

Boots in Action

Well-Known Member
Mar 13, 2017
2,053
1,804
113
Ferny Grove, Queensland
Also someone has shown what I thought for ages in that some of these fridge covers actually restrict air flow around the heat exchange parts, making them work harder, just a thought.
Yes @Drover, I have read something about that too. It had to do about where the insulating/protective cover partially covers the compressor area, although the hot air exhaust still remains unobstructed. May not apply to all models/makes. Will see if I can find any more info. It is not only that area, but the inability of the heated air to get well away from the proximity of the fridge ie into the open air.
 
  • Like
Reactions: Drover

Drover

Well-Known Member
Nov 7, 2013
12,723
19,450
113
QLD
Yes @Drover, I have read something about that too. It had to do about where the insulating/protective cover partially covers the compressor area, although the hot air exhaust still remains unobstructed. May not apply to all models/makes. Will see if I can find any more info. It is not only that area, but the inability of the heated air to get well away from the proximity of the fridge ie into the open air.

Ive always thought that myself and laugh at the high price they charge for an alloy box to put your fridge in,more like an oven, with a couple of dinky slots for air, in the young fellas we cut extra holes and fitted a 12v fan to extract and it worked well with some insulation of the box..... wet bag thrown over the Engel always worked well with the workings in the open.