A real solar generator

[Almost There]

My Iota charger seems to always kick in to bulk on start up while it tests the battery bank.

At bulk stage charging I can hear the two 1000 W genies I use revving slightly, not full output but more than an idle. And depending on how far down the batteries have been drawn, I can hear the two of them idling down after time has passed. I've even had one run out of gas and the other continued to run the charger just fine but it was after it was already on float!

 

[John61CT]

Need an ammeter to gauge the actual load, batt acceptance.

LFP would be the real test, that's where derating's really needed, 100AH can accept 3-400A no problem (if BMS allows)

 

[jimindenver]

Jim: 

After much thought I decided that I have enough weight up high on the trailer now.  So adding the extra wings onto the existing array seems not such a good idea. 

I'm thinking about putting a single 160w or so panel in front of the roof tent on the van.  With a charge controller that will charge two batteries, a smallish AGM dedicated to the Engel fridge in the van and also to keep the starting battery topped off.  Doing so would simplify my life by eliminating the daytime charging of the battery in the trailer that is used to power the Engel in the van at night.   Thoughts?

The Morningstar duo will charge one battery and then another. It is PWM and I would have to see if it can be set like the Tristars can. I would be concerned with mixing the battery types for a single setting but the starting battery has to see some pretty high voltages off of the alternator if I remember right.

 

[29chico]

The Morningstar duo will charge one battery and then another. It is PWM and I would have to see if it can be set like the Tristars can. I would be concerned with mixing the battery types for a single setting but the starting battery has to see some pretty high voltages off of the alternator if I remember right.

The Duo looks promising.  My starting battery is a rebranded Duracell AGM made by East Penn that is also sold as the Deka Intimidator and is used in extreme audio builds.  So I guess that I could go with around a 30-40ah battery of the same construction from East Penn.  Should be plenty of overkill to run the Engel in the van in fresh food mode overnight.

 

[John61CT]

Running any fridge much less two, I would highly recommend a 200+AH bank.

Under 100AH, will usually be shortening lifespan.

IMO gotta size for 2-3 days worst-case solar conditions, and with all that panelage you are very well positioned to get the bank back to full once insolation improves.

Unless your dino-juice sources are available on demand.

But really, a bigger bank, e.g. a $180 200AH pair of Duracell GCs, will help you get **so** much more use out of that solar capacity than adding a piddly 40AH.

 

[jimindenver]

On cloudy days he may have to resort to using the big array to charge up like he has been already. It has to be pretty bad before 1100 watts total can't handle those two small batteries. He could always use the truck or even my little generator that actually stayed home today.

You have to understand that his build is like mine with out the big bank. It is meant to power things during the day without his batteries knowing just like I run my A/C or water heater. The difference is that I use a lot more power staying up until 3 AM watching TV, working on the computer, booster, running lights, fans and the furnace plus running my Engel. I am averaging 250 Ah's a day right now, a bit higher today since I had someone plugged in and using the internet to run a gaming computer.

 

[John61CT]

Yep lots of decent sized cruising yachts use less than that!

 

[jimindenver]

Just wait till I start running that A/C a good portion of the day. That can double the count right there.

 

[John61CT]

I want to see the system that lets it run all night.

 

[jimindenver]

I have enough battery to run my A/C all night if needed but I do not have the panel to replace that usage and run the A/C all day too. It was designed for use at high altitude where A/C is rarely needed and never at night. Wintering in the desert is much the same, in fact I have only needed the A/C once since coming down this fall, yet need the furnace every night.

Now then. Had I thought I needed to run it all night I could have upped the wattage on the roof of the trailer by going with three of the 435w panel I have on the truck for over 1700w total or over 120 amps at 12v. That would have taken care of the batteries while still having enough to run it at the same time. The issue was losing my TV antenna to make room for the bigger panels and the limited number of charge controllers that can handle that kind of wattage. (what can take 1300w?) I could add close to 700 watts by hanging panels off the front and rear but that would mean at least one more controller, switch, fuses, wires, etc just to prove that 24 hour A/C on solar is possible. I already proved the A/C on solar concept. Someone else can take on the 24 hour thing.

 

[John61CT]

Yes, more useful to someone say living on the gulf in summer.

At some point going to the very efficient 48V DC aircon models must make sense, especially when higher BTU needed.

 

[scottorious]

The issue was losing my TV antenna to make room for the bigger panels and the limited number of charge controllers that can handle that kind of wattage. (what can take 1300w?)

Assuming that you have a 12 volt system there is a Victron controller that will handle 1450 watts. Moving up to 24 volts would mean the same controller would take 2900 watts. Your system is cool!

 

[29chico]

Running any fridge much less two, I would highly recommend a 200+AH bank.

Under 100AH, will usually be shortening lifespan.

IMO gotta size for 2-3 days worst-case solar conditions, and with all that panelage you are very well positioned to get the bank back to full once insolation improves.

Unless your dino-juice sources are available on demand.

But really, a bigger bank, e.g. a $180 200AH pair of Duracell GCs, will help you get **so** much more use out of that solar capacity than adding a piddly 40AH.

I have powered the Engel MT35 in the van, in fresh food mode, overnight, many nights, with a 16AH Odyssey battery.  Most nights it draws about 3-3.3Ah.  After a hot night I saw right about 5Ah consumption on the Powerwerks meter.   The MT35 in the cargo trailer in freezer mode, set at 5 degrees F, will draw about 50% more on any given night.  So 7-8Ah out of the 102Ah Northstar AGM overnight is not an issue.  These are real world numbers.

Honestly, I see no need for more Ah at this point.  The piddly 16Ah Odyssey is still very happy.  From what I have seen, a 40ah battery running the MT35 van fridge overnight in fresh mode would be serious overkill, not piddly.  

Anyone who thinks that my system is wacky or wrong, so be it.  Don't build one like it...

 

[John61CT]

No that's great, most reefers consume lots more, and over double in freezer mode.

Few measure loads so accurately, good on ya

 

[highdesertranger]

Engel's are very efficient. highdesertranger

 

[SondraRose]

From what I have seen, a 40ah battery running the MT35 van fridge overnight in fresh mode would be serious overkill, not piddly.  

Anyone who thinks that my system is wacky or wrong, so be it.  Don't build one like it... [\quote]

Love the real world numbers, thanks!  

We are planning to get an Engel MR40 and run it (and our electronics) off a 90 ah lithium power pack.  Overkill works for me!

 

[29chico]

From what I have seen, a 40ah battery running the MT35 van fridge overnight in fresh mode would be serious overkill, not piddly.  

Anyone who thinks that my system is wacky or wrong, so be it.  Don't build one like it... [\quote]

Love the real world numbers, thanks!  

We are planning to get an Engel MR40 and run it (and our electronics) off a 90 ah lithium power pack.  Overkill works for me!

I would suggest that you consider a mt35 or mt45 Engel if you want to get max efficiency.  The mt Engels have the ability for the warm air coming off the condenser to thermo siphon up and out the top vent w/o the cooling fan running much, or at all, when the compressor is running.  The MR40 and every other brand of 12v fridge that I'm aware of does an in one side and out the other condenser cooling setup.  So the fan needs to run whenever the compressor is running.  This constant running of the compressor cooling fan will also result in the condenser, and everything near it, getting more dust on it more quickly.

 

[SondraRose]

Really helpful info, thank you!

 

[John61CT]

Are Norcold the same maker, or do they both just share the same Sawafuji compressor as opposed to the Danfoss type used by everyone else?

 

[29chico]

Are Norcold the same maker,  or do they both just share the same Sawafuji compressor as opposed to the Danfoss type used by everyone else?

The older Norcold 12v portable fridges did use the Sawafuji compressor. 

I just looked at the wiring diagrams for the current Engel and the Norcold portables.  The Norcold uses three wires to a Y winding to power the compressor and the Engel uses two wires to a simple coil winding.  Based on this I think that the Norcold units are now using a traditional crank, rod and piston design.  Not totally sure as designing electric powered compressors is not my forte.

Not that it matters to me, as the parts list for the Norcold and it is nowhere near as complete as the Engel.  For example I could buy an entire sealed cooling system for a Engel mt-35 for around $370, last time I checked, and install it myself.  The sealed system is completely charged and ready to go into service.  No need to ship the whole unit to Engel.  No soldering the system together, then evacuating and charging it. Smart.