Poor Mans Inverter Project

[Midnightsun]

I have always been against large inverters as the power removed needs to go back in and this takes time so might as well run the generator for short periods when large draw appliances are needed not to mention this charges the batteries at the same time. I do have a couple of small inverters installed to handle TVs, entertainment and small electrical draws elsewhere.

Well since I am installing a rather large LifePo4 Lithium bank and have solar and the means to charge at 80 amps, I figure what the heck, lets get the kitchen outlet that does the coffee machine, frother and blender hooked up to do at least what a 15A circuit can handle IF required on the rare occasion. Morning coffee with guests sleeping comes to mind or anchored out close to someone early morning.

Want to keep this compact and simple and relatively inexpensive.

The Lithium bank is under the galley floor just below the outlet in question, how convenient.

After advice from other I have decided to go with a 2000 watt Renogy pure sine wave unit. https://ca.renogy.com/2000w-12v-pure-si ... -inverter/

To make switching between shore power and inverter seamless and safe, an automatic transfer relay will be used. https://www.amazon.ca/gp/product/B004S5Y158/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

The unit will be turned on/off at the Galley via the supplied switch from Renogy

The all important fuse. Elected to go this route to simplify wiring and I also have a smaller multi fuse box connected to my house bank which would be better protected if there was a fuse directly at the battery so I opted for the dual unit. Will end up with a 200a fuse for the inverter and an 80a fuse for the remote fuse box. https://www.bluesea.com/products/2151/D ... 30_to_300A

When disconnected shore power or generator power the relay connects the inverter automatically which is what the goal was. Obviously the opposite happens when shore power or generator power is supplied . Inverters draw power even in the off state so this is where the manual on switch comes into play. Push the on/off button and the power light comes on and powers up the inverter/outlet ready for use. The light is a constant reminder to turn it off when done, not that it matters however why use battery energy when not required. An inverter of this size does consume a whooping 2A in standby. Thats almost like running a small fridge!

Keep in mind I have LifePo4 lithium so no off gassing therefor the inverter can be mounted beside the bank and the bank is under the galley floor and not in the bilge.

A little bit of custom wiring and about $500-600 in parts when all is said and done. Pictures to follow as things progress.

[Viper]

I agree Hans, full integrated systems while convenient are expensive and require a level of power management to minimize unnecessary drains. They also tend to be way more dangerous if not installed properly and you run the risk of loosing all power even shore power if the passthrough circuit fails. I have a couple of small dedicated inverters too, they're handy, and the appliances run off them even when I'm on shore power, I mean why not, the charger looks after maintaining the bank's capacity during that time anyway. These are smaller loads though like the TV, computer, etc.

I would look deeper into lithium battery gassing off though. Under the right conditions, it's not uncommon to have a gassing off event.

[Midnightsun]

Lithiums is really taking over the RV/van world when it comes to house banks. Batteries are stored under the bed and in confined spaces. Some have ventilation however this is more for keeping the heat down in the confined space and they ventilate inside the vehicle most of the time. Todays built in BMS (Battery Management System) all but eliminate battery failure by disconnecting when issues are detected. Go back several years and there was an issue but pretty much solved now with BMS. Lithium off gassing only occurs when the battery has failed as in bye bye no more. I would worry more about the possible fire than the off gassing at this point however this is very rare otherwise Lithium would be labeled with multiple warnings and would be a lawyers dream come true.

Good point though.

That being said, chit happens. This was in the news this morning. Ebikes from China are sometimes not exactly top quality especially with those little brick chargers that come with them. Overcharging seems to have been the cause here. Goes to show how important a good BMS and charging system is. https://www.nsnews.com/local-news/north ... re-5276734

[km1125]

When adding inverters (or really any stand-alone power generation), you need to consider how the neutral and ground are handled.

On shore power, the neutral and ground are connected at the shore breaker panel - the "source" - and should be connected no where else. When you have an on-board generator - whether that be a gas or diesel unit or an inverter - you also need to connect the neutral to ground. This connection needs to "go away" or be isolated when you are connected to shore power so you're not making a second connection when back on shore power. Normally the auto-transfer switch takes care of this in the generator scenario and in a marine inverter with a built-in transfer switch they do the same thing. If your boat has an isolation transformer, the connection is made on the output side of the isolation transformer.

Other applications need to address this issue correctly.

[g36]

Modified sine wave invertors cannot have the neutral and ground tied together it will fry it. Pure sine wave sometimes are different but which ever you must verify with the manual for the inverter about the grounding.

[Midnightsun]

As Viper mentioned this is not a whole house system, simply controls a single outlet without all the complexities/expense of a whole house system. If you look at the unit, there is not even a means of grounding the frame. These units are meant to be plopped down on the engine of your car and jumped from your car battery. Cannot see how I can be supplying a new ground or interconnecting one with this setup. No different than the smaller point of use units many use. The unit is off all the time unless we forget the manual switch and even then the auto transfer relay is preventing back feed. Appreciate the comments though as nobody is perfect and as a collective we can sort out any unforeseen issues.

[Rocketman]

I purchased this pure sine wave inverter that comes with the on/off remote switch and battery monitor.
https://www.amazon.com/gp/product/B07MTXZVBJ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
I also wired mine in with a relay to the generator breaker on the main power panel.
https://www.amazon.com/gp/product/B07FCJFGL9/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
This way when the generator is on - the relay automatically disconnects the inverter.
I also wired to the output of the inverter off this relay to additional small relays to turn off the battery chargers and the hot water heater automatically. This way you don't get a large load from the water heater and a never ending circle of current from the chargers trying to charge batteries from the batteries.
https://www.amazon.com/gp/product/B087G6D24G/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

I purchased 2/0 cable from Lowes and connectors to power the inverter that is setting next to my battery power distribution/isolation node in the floor that I am pulling the battery power from.

I saw where you can get 2/0 cables from Harbor Freight already made for about the same price.
https://www.harborfreight.com/3-ft-inverter-cable-set-20-awg-63748.html

Came to about $400.00 w/ wiring and everything. Now I have whole boat Pure Sine Wave inverter system for TVs, Coffee, Blender, even microwave for a couple minutes.

I also have solar panels on the hard top to keep everything charged during the day.

[bud37]

Here are some things that need to be considered when wiring up new appliances/devices on board your boat.

West marine has a quick read, there are much more detailed articles available with some quick searches.

https://www.westmarine.com/WestAdvisor/ ... Conditions

[Viper]

Source of the post Lithiums is really taking over the RV/van world when it comes to house banks. Batteries are stored under the bed and in confined spaces....

This is common but my concern is placing an appliance in the same space that is not ignition proof.

Source of the post....Todays built in BMS (Battery Management System) all but eliminate battery failure by disconnecting when issues are detected.....Lithium off gassing only occurs when the battery has failed as in bye bye no more.....

Over charging will do it too...

Source of the post That being said, chit happens....Goes to show how important a good BMS and charging system is....

That's the thing though isn't it? You're relying on and hoping that an electronic component doesn't fail and result in a runaway condition while charging, and charging is when most failures happen with these. We all know how reliable electronics are these days...NOT.

I have no problem with using properly installed lithium battery systems, I just wouldn't put the inverter next to the bank as you've indicated.

[Midnightsun]

I need to change my terminology here as I am using Lithium which is not the case in the battery type commonly used in boats and RVs today. The correct name or better yet "structure" of the Lithium is LifePo4 and is in fact what I have. Long read but this explains it. learning more and more every day.

Lithium is a reactive metal. It’s so reactive it will react with water. What that means is if the electrolyte ever dried up somehow and the two metals inside came in contact, the battery could explode or at the least catch fire.

That drawback kept lithium batteries from coming to the major consumer market for some time. It is also a worry you will find discussed in many RV forums. Many have heard of manufacturing defects in laptop and cellphone batteries melting or catching fire next to a person’s face.

To put this in perspective, millions of lithium-based batteries are manufactured each year, and very few malfunctions happen. You are more likely to wreck an RV on the road than have your cell phone spontaneously combust. RV lithium batteries come with a battery management system or BMS built into them that regulates charging, discharging, and other factors to prevent damage.

Another factor to consider when thinking about the safety of lithium batteries is their makeup. There is a reason that most RV lithium batteries are of the LiFePO4 type. According to RELiON’s FAQ page,

“Phosphate-based batteries offer superior chemical and mechanical structure that does not overheat to unsafe levels. Thus, providing an increase in safety over lithium-ion batteries made with other cathode materials…Lithium phosphate cells are incombustible, which is an important feature in the event of mishandling during charging or discharging. They can also withstand harsh conditions, be it freezing cold, scorching heat, or rough terrain.

When subjected to hazardous events, such as collision or short-circuiting, they won’t explode or catch fire, significantly reducing any chance of harm. If you’re selecting a lithium battery and anticipate use in hazardous or unstable environments, LiFePO4 is likely your best choice. It’s also worth mentioning, LiFePO4 batteries are non-toxic, non-contaminating, and contain no rare earth metals, making them an environmentally conscious choice.”