Which charger+inverter?

[hardtop]

I'm looking for help to build a DIY UPS for home that will also be an energy source while overlanding. A generator will be used to recharge the batteries while overlanding. I picked a JK BMS and LIFEPO4 batteries, but they didn't have a charger+inverter or wires for the BMS. For the inverter+charger, I need about 700 - 800 watts for the inverter and 20-25 amps for the charger in a pure sine wave for computer gear that is silly expensive.

I looked at the Victron site and every inverter+charger I picked turned out to only be sold for Europe, the MultiPlus 12/1200/50 and MultiPlus 12/1600/70. I'm attracted to their output specs at specific temperatures because I'll be in hot areas and will hit 40C repeatedly.

I also looked at Samlex and their lowest output inverter+charger and they don't discuss output at specific temps. The Samlex looks smaller and I like the look and shape of it better for my use case compared to the VIctron but I'm looking at the wrong Victron products. Samlex is saying I can adjust the charge amps so I would assume the Victron would offer the same feature or better.

How many amps will my generator need to output to charge the battery pack at 25A and which inverters+charger should I be looking at?

 

[400bird]

Have you checked out the Victron Phoenix line? That may fit your needs if you add a charge controller.

How many amps will my generator need to output to charge the battery pack at 25A and which inverters+charger should I be looking at?

It's just math.
A 12 volt battery prob tops out around 14 volts when fully charged.
14 volts x 25 amps = 350 watts. Add in some headroom for inefficiency, you should be well under 400 watts.
So, basically any generator should be able to handle it.

 

[hardtop]

Have you checked out the Victron Phoenix line? That may fit your needs if you add a charge controller.


It's just math.
A 12 volt battery prob tops out around 14 volts when fully charged.
14 volts x 25 amps = 350 watts. Add in some headroom for inefficiency, you should be well under 400 watts.
So, basically any generator should be able to handle it.

Thanks for the help on the generator output requirement. I didn't look at the Pheonix line since I need an inverter+charger. When pulling from the inverter I need automatic switching from AC to battery if the AC drops.

 

[DIYrich]

Off-Grid inverter?

Growatt 3kW Stackable Off-Grid Inverter | SPF 3000TL LVM-24P

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

signaturesolar.com

What's wrong with this Victron?

https://www.victronenergy.com/upload/documents/Datasheet-MultiPlus-II-3kVA-2x120V-EN-.pdf

 

[hardtop]

Off-Grid inverter?

Growatt 3kW Stackable Off-Grid Inverter | SPF 3000TL LVM-24P

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

signaturesolar.com

What's wrong with this Victron?

https://www.victronenergy.com/upload/documents/Datasheet-MultiPlus-II-3kVA-2x120V-EN-.pdf

The MultiPlus II looks nice. The 18650 battery store liked it too, but it is 3x the power that I need. If I run 700 watts off of it, would it be less efficient than an inverter+charger that has a much lower output? 700-800w is my max and I'll be running less normally. It would be interesting to look at power curves to compare them. Some PC power supply manufactures advertise a power graph so you can pick which model to get based on the efficiency at the target power output.

 

[DIYrich]

The MultiPlus II looks nice. The 18650 battery store liked it too, but it is 3x the power that I need. If I run 700 watts off of it, would it be less efficient than an inverter+charger that has a much lower output? 700-800w is my max and I'll be running less normally. It would be interesting to look at power curves to compare them. Some PC power supply manufactures advertise a power graph so you can pick which model to get based on the efficiency at the target power output.

If there are no good alternatives, does the efficiency curve really matter? If you found 2 or more products that meet your need, then by all means compare whatever features are important to you.

Running an inverter at 30-40% of load is probably in a good part of the efficiency range. Especially if you will be running in harsh environments. I wouldn't want to be running an inverter at 80% of load when it is 40c degrees. It may get warm at 40%, and hot at 80%. You should also consider power stability at the higher end of the operating range. A lot of inverters can't put out the name plate rating. Headroom is your friend. Finally, VA is not the same as watts. At 75% of the watts, you could be close to 100% of VA.

I'd be more worried about the efficiency of your generator at the power point you will be using.

 

[Tomthumb62]

Thanks for the help on the generator output requirement. I didn't look at the Pheonix line since I need an inverter+charger. When pulling from the inverter I need automatic switching from AC to battery if the AC drops.

Unless you require the expense and packaged look of a two in one device, you can go components. Separate inverter, charger and automatic switch. If any one part fails, easy and cheaper to replace.

 

[400bird]

I didn't look at the Pheonix line since I need an inverter+charger.

Well, I learned something today. I just assumed the Phoenix line was inverter/charger. Not just inverter.

 

[hardtop]

Unless you require the expense and packaged look of a two in one device, you can go components. Separate inverter, charger and automatic switch. If any one part fails, easy and cheaper to replace.

I'd like to explore separates since it would allow customization opposed to an all-in-one, but I'm not sure what the switch is called. Any ideas?

 

[hardtop]

If there are no good alternatives, does the efficiency curve really matter? If you found 2 or more products that meet your need, then by all means compare whatever features are important to you.

Running an inverter at 30-40% of load is probably in a good part of the efficiency range. Especially if you will be running in harsh environments. I wouldn't want to be running an inverter at 80% of load when it is 40c degrees. It may get warm at 40%, and hot at 80%. You should also consider power stability at the higher end of the operating range. A lot of inverters can't put out the name plate rating. Headroom is your friend. Finally, VA is not the same as watts. At 75% of the watts, you could be close to 100% of VA.

I'd be more worried about the efficiency of your generator at the power point you will be using.

The physical size of the unit matters and I might be buying much more than I need and that cash could be used elsewhere. On the other hand, if I buy more than I need I have room for growth and could power more things than I initially planned to. I'm not worried at all about the generator efficiency, just going as long as I can off a charge.

 

[Tomthumb62]

I'd like to explore separates since it would allow customization opposed to an all-in-one, but I'm not sure what the switch is called. Any ideas?

No idea if this model is any good, but this is an example:

MOES Dual Power Controller 50A 5500 Watt Automatic Transfer Switch for Off Grid Solar Wind System ATS DC 12V 24V 48V AC 110V 220V. https://a.co/d/bCuvXPP

 

[DIYrich]

I'd like to explore separates since it would allow customization opposed to an all-in-one, but I'm not sure what the switch is called. Any ideas?

Chargeverter can convert AC (grid or generator) to DC. I would set it for a float voltage, and leave it at that.
48v Inverter

https://www.amazon.com/KRXNY-Inverter-Display-Output-Socket/dp/B082HJBM8L

If you want to charge from panels, then an MPPT Charge Controller.

Victron setup:
Charger

Charger - Victron Energy

Automatically optimize the charging process with the Adaptive 4-stage charge characteristic of the Charger. Find a dealer near you.

www.victronenergy.com

Inverter

Inverter Compact 1200VA - 2000VA - Victron Energy

Developed for professional duty, the Inverter range is suitable for the widest range of applications. Learn more now.

www.victronenergy.com

BTW: You don't need a "switch". The inverter always runs off the battery.

 

[hardtop]

Chargeverter can convert AC (grid or generator) to DC. I would set it for a float voltage, and leave it at that.
48v Inverter

https://www.amazon.com/KRXNY-Inverter-Display-Output-Socket/dp/B082HJBM8L

If you want to charge from panels, then an MPPT Charge Controller.

Victron setup:
Charger

Charger - Victron Energy

Automatically optimize the charging process with the Adaptive 4-stage charge characteristic of the Charger. Find a dealer near you.

www.victronenergy.com

Inverter

Inverter Compact 1200VA - 2000VA - Victron Energy

Developed for professional duty, the Inverter range is suitable for the widest range of applications. Learn more now.

www.victronenergy.com

BTW: You don't need a "switch". The inverter always runs off the battery.

I need a switch because the inverter always runs off the battery. I'd like to draw energy from AC input if it is supplied. I'm pretty sure the tech exists, RV's have that feature. When they are plugged in they aren't drawing from the battery.

 

[hardtop]

ttt

 

[740GLE]

I’d say the best option is the multiplus (add a SCC if needed).

The Multiplus has very low idle current and allows for seamless grid back up.

Seeing you won’t need to mount and wire an inverter and charger the MP II size is actually smaller than going separates.

 

[hardtop]

I’d say the best option is the multiplus (add a SCC if needed).

The Multiplus has very low idle current and allows for seamless grid back up.

Seeing you won’t need to mount and wire an inverter and charger the MP II size is actually smaller than going separates.

With the Multiplus, will the inverter draw from the AC input if it is up? What is SCC?

 

[12VoltInstalls]

What is SCC

Solar charge controller

physical size of the unit matters and I might be buying much more than I need and that cash could be used elsewhere. On the other hand, if I buy more than I need I have room for growth and could power more things than I initially planned to

if money up front is an objection the 12V MPPSolar all-in-one products will handle your generator, contain a charger, and meet your wattage requirements. Inexpensively.
Just don’t know if you intend to add some panels (I definitely would!!)

I have as one of my devices a 1012LV-MK that works fantastic. I currently configured it for “USB” and do not have the inverter switch on (I use a separate 2000W pre sine inverter). In your case, you would leave the inverter switch on.

It has pure sine wave output, and automatically when you start the generator it will charge the batteries. Just power its input with a cord; if it’s plugged into the generator it will use the generator. If you instead plug to shore power it will use grid.

For the money you can’t do better for dependability or features and the 1012LV-MS model is under $500

 

[hardtop]

Solar charge controller

if money up front is an objection the 12V MPPSolar all-in-one products will handle your generator, contain a charger, and meet your wattage requirements. Inexpensively.
Just don’t know if you intend to add some panels (I definitely would!!)

I have as one of my devices a 1012LV-MK that works fantastic. I currently configured it for “USB” and do not have the inverter switch on (I use a separate 2000W pre sine inverter). In your case, you would leave the inverter switch on.

It has pure sine wave output, and automatically when you start the generator it will charge the batteries. Just power its input with a cord; if it’s plugged into the generator it will use the generator. If you instead plug to shore power it will use grid.

For the money you can’t do better for dependability or features and the 1012LV-MS model is under $500

Thanks for the tip. That does look like a nice setup with a celebrity-like endorsement. I'd like to do solar don't have space for solar panels. I'll be charging using the wall and a generator.

 

[12VoltInstalls]

celebrity-like endorsement.

LOL

I'd like to do solar don't have space for solar panels

You must have some space on top?

Even if it’s only a couple commodity 100W panels - you be surprised how far just a little 200W input can sustain a small battery bank over the course of a day. This works “better” with LiFePo because they don’t need to achieve a full charge daily- they’ll ’hang’ at 60% or whatever without damage. Not so with lead batteries.

I don’t recommend renorgy anything but I ‘might’ consider their rebranded panels though since they are commodities. I would recommend these windy nation panels; I have six- they work well and are compact. You might be able to accommodate their small footprint. Similar are the BougeRV panels.

Windy Nation has been great to deal with- once I was pondering some stuff and came up with a light technical question. I emailed them- forget now if it was New Year’s Eve or Christmas Eve but I was pretty shocked to get an answer back the next morning. First class imho.

 

[740GLE]

With the Multiplus, will the inverter draw from the AC input if it is up? What is SCC?

Yes it works as a UPS.

A SCC is completely optional and separate system you’d connect to your battery bank.