Inverter / lithium battery installation

[jamieline]

In the process of deciding on which refrigerator i will install I will be installing an inverter and changing to lithium batteries. In my reading I have a couple of questions for the folks that have done this or have it.
In reading about the installation of the inverter, it states to not install in the same compartment as the battery bank. Is this more related to lead acid batteries?
In everything I have seem it seems like the lithium batteries do not need to be vented, correct?

If I get an inverter/changer with auto transfer switch, will the unit always be on for charging when hooked to shore power?
The only time the unit would be shut off is when not using the trailer?

I plan on connecting 2 batteries. At this time no solar is planned as we do not boondock at this time. The only concern may be a stop at Harvest Host for an over night stay and the batteries may be used for 36 hours before recharging. Main draw would be refrigerator.

Thanks

[Country Campers]

The Multiplus 2 will be on all the time unless shore power and battery power is removed. It will also be on for charging when on shore power if the switch is set correctly. This information is if you go with the Victron Multiplus 2.

For your 2 battery setup remember that it takes 10 amps DC to make 1 amp AC, important when calculating usage and battery bank size.

Brian

[howson]

jamieline -- yes, warning is regarding kead acids.

With two batteries stick with 2kW or less inverter--need minimim of three batteries (four better) to get full use of a 3kW inverter due to max amperage a single battery can deliver.

[jamieline]

I am looking at a 2000w unit. Main thought at this time is powering the refrigerator on travel days.
Still looking at what an overnight stop at a boondock location would need. Thinking lights, water pump but could keep those at a minimum.

[Jlawles2]

jamieline Lights and water pump are 12V thus will not be part of the draw on a 2kW inverter. Keep the HWH on gas only when boon docking also as the electric option will draw a lot of wattage.

[TucsonJim]

jamieline -- yes, warning is regarding kead acids.

With two batteries stick with 2kW or less inverter--need minimim of three batteries (four better) to get full use of a 3kW inverter due to max amperage a single battery can deliver.

For anyone reading this in the future, here's the rationale using a typical 100 amp hour Battle Born Battery

Power = Voltage x current.

To get a continuous 3000 watts of 12 volt DC power - 3000W/12V = 250 amps.

Battle Born 100 amp hour LiFePO4 batteries can produce 100 amps of output power (200 amps surge) continuously. If you put two in parallel, that will provide 200 amps of continuous power.

A 3000 watt converter running a maximum draw will need 250 amps of continuous power which two batteries can not provide.

JIm

[TedS]

On the other hand if I have a 3000 watt inverter and my ac load is 1000 watts, I need only 83 dc amps. The point is the inverter will deliver only what the demand load is unless the inverter does not have the capacity for the load.

[JRKJR]

Still looking at what an overnight stop at a boondock location would need. Thinking lights, water pump but could keep those at a minimum.

Lots of variables, temperature, how often the fridge door gets opened, the efficiency of the fridge, etc.

As a ballpark to get you started. Our stock Samsung residential pulls an average of around 8-10DC amps per hour including other parasitic loads and the inverter loss. Start adding fans, lights etc it goes up quickly. We have a Victron 3000w multiplus.

[acoleman43]

We swapped our 2 way fridge for a DC fridge. We had two AGM batteries and a 300W panel. I thought this was plenty as the fridge only draws 7-8 amps at highest setting.

First trip out was a 5 hour drive to camp. When we setup the person in charge of plugging into shore power forgot to plug into shore power. about 5 hours after we setup (about 3 hours of no light) the batteries had drained to a point that the voltage was too low for the fridge to run. That's when I found out we weren't plugged into shore power

SO, from my experience, you don't have very many hours of run time when you have kids using lights, charging computers/phones, watching tv........