It's working but....suggestions?

[Swamplizard]

Conversion van has LV2424 (finally working), 2x100Watt flexible solar panels on roof in series, 24v 280AH LifePo4, 240watt 12v to 24v DC to DC converter.

Couple of questions:

1) Fridge is a dorm 120v unit running off inverter in LV2424. When running LV2424 plus fridge seems to consume 100watts/hr until fridge is cold then it cycles and uses much less. The LV2424 uses 25 watts/hr by itself. The two 100Watt solar panels in series are pushing about 100watts 4-6 hours a day so they do not keep up with worst case scenario of 2,400 watts consumption (100wattsx24 hours). I plan on adding two more 100watt panels in series so I will soon have 2S2P and hopefully 200watts/hour to battery 4-6 hours a day. There is no room for more than 4 panels. Hoping to get it to a point where it is a "wash" when parked in FL. If it doesnt work out - how much power do the 12v/24v fridges use? Would it make more sense to use a smaller separate inverter just for the fridge? Would this be more efficient than the LV2424 and its overhead?

2) DC to DC converter is bluetooth but not much info available. It says if it is on or not and what phase of charging it is....no totals. It is connected to 24v main battery connections (fused) on positive and shunt on negative. Should I add a flow meter to it or just trust that it is doing its thing when van is running?

Thanks for any recommendations or thoghts/ideas.

Swampy

 

[sunshine_eggo]

Flex panels will degrade quickly during summer. They get so hot on top of a vehicle roof, their performance drops off.

RARE that your fridge would run 24hr/day unless you leave the door open or expose it to direct sun all day, or the interior of the vehicle is extremely hot.

Fridges of a given volume consume about the same amount of energy. 12/24V will consume less than 120VAC. I do recall that 24V can use a surprising amount less than 12V on some models. If nothing else, it saves you the 25W burn of the LV2424.

I'm lazy, so it's worth spending $70 on a cheap 500W PSW inverter to find out if that improves things:

https://www.amazon.com/BESTEK-Inverter-Adapter-Converter-Charging/dp/B082MDRC64

Concerning the DC-DC, if you don't have a clamp ammeter, they're very useful tools. I'd get one and verify it's flowing current.

Do you have a battery monitor?

 

[mikefitz]

The Lv4242 is not ideal for a van conversion.

A 12/24 DC fridge will consume about 50 watts with the compressor on and when at temperature will cycle with around a 30% duty cycle, 400 watts per day. Marine/RV DC fridges will be more efficient than a dorm fridge with better insulation and a forced air heat exchanger.

If you have a shunt on the battery why not use this to monitor charging?

A quality inverter 500 watts with good overload capacity may run the AC fridge. Its possible to select an inverter with under 5 watts standby power consumption, look at the Victron range.

You need some kind of monitoring if you have not already have such a system.

Unless there are compelling reasons for using flexible panels change to rigid framed panels when you update .
Its usual for flexible panels to partially fail within a short time and rarely last more than two years.

Mike

 

[12VoltInstalls]

I ran a 120V fridge about twice the capacity (5CF) of a dorm fridge all summer on 400W solar 2S2P - plus a coffeemaker lights and water pump, vacuum cleaner.
~300Ah usable lead acid was just barely enough.

I experimented with a dorm fridge a few years back and did 4 or 6 weeks w/ 200W. You *can* do that with 200W when the sun is good. But it’s not recommended. If you have a cloudy period it probably won’t cruise more than a day.

You need at least 400Wbof panels; a second battery and 600W would be much better. 800W would seem useful for

 

[Swamplizard]

Thanks Folks - I use the shunt to monitor over-all power use and charging.....for solar, shore and alternator flows.

The 25watts per hour adds up for the LV2424 but we are in FL so needed something that could drive an A/C when needed from shore power and from battery (at night) as well as drive a microwave and electric stove top. The LV2424 does all of those things well at a high idle cost. Will look into a small separate inverter for when we dont need all of those capabilities (like when RV is parked for a few weeks) and just drive the fridge.