Replacing a Promatic 30-3 with an Inverter/Charger

[Tenedos]

We are spending more time on the hook and lack of AC is becoming a problem. Portable inverters don't exactly meet the need for various reasons.

I have lead acid batteries. I have started contemplating to replace my existing charger (Promatic 30-3, photo attached) with a TruePower Combi Inverter/Charger but honestly I am not sure if I am looking for trouble.

I am space constraint on a 32ft boat so I hope having a combo unit will save me some space and prevent installing new thick cables from the batteries.

I will appreciate thoughts and tips.

[smac999]

not sure what you mean not needing thick cables.

An inverter or inverter charger will both need thick cables.

[Dsanduril]

Easiest way to think about it, your 30A charger is ~420W. A 2000W inverter is 5x that much. You’ll need bigger cables. Much bigger cables.

[Tenedos]

Originally Posted by smac999

not sure what you mean not needing thick cables.

An inverter or inverter charger will both need thick cables.

I mean I want to use the existing cables but @dsanduril’s point in the next post is spot on.

[Pete7]

Originally Posted by Tenedos

I am space constraint on a 32ft boat so I hope having a combo unit will save me some space and prevent installing new thick cables from the batteries.

I will appreciate thoughts and tips.

That inverter charger is a hoofing great lump and not cheap either, check the weight.

Since you are planning spending more time on the hook, why do you need a new mains charger rather than continue to use the existing one?

What you might want is a new inverter, probably pure sine wave. Just be aware that even a 1000w inverter will draw 80A at 12.5v. That's a lot for a small yacht battery system.

We have similar issues, so use a 100w and 350w inverter most of the time, but have the big boy 1000w inverter if we need it for a short burst for the main electric drill or hoover.

Put it another way, the starter motor on my 28hp engine is 1100w. Wouldn't want to turn the engine over on the house bank for long if the engine didn't start.

Pete

[ranger58sb]

We installed a ProMariner 2000W/70A Combi on one of our house banks, and it worked fine. No way around the proximity and wire size requirements; it needs what it needs.

We didn't install ours in the same location as our original charger. Instead, we installed the new unit according to the manual's recommendations: close to the battery bank, and with fat wires.

You can download the manual in advance and have a look at those instructions...

-Chris

[Tenedos]

Originally Posted by ranger42c

We didn't install ours in the same location as our original charger. Instead, we installed the new unit according to the manual's recommendations: close to the battery bank, and with fat wires.

You can download the manual in advance and have a look at those instructions...

Thanks Chris. I looked at the manual. Unfortunately, I don't have the room to install the charger to a closer position, space is really limited.

Following Pete's suggestion:

Originally Posted by Pete7

What you might want is a new inverter, probably pure sine wave. Just be aware that even a 1000w inverter will draw 80A at 12.5v. That's a lot for a small yacht battery system.

I am trying to see if I can install a separate 1500w inverter, somewhere closer to the battery since it is smaller but then it sounds complicated to integrate it with the charger. Ideally I would like to connect the inverter to existing outlets and AC system but then it has a risk of causing a loop (shore power to battery, battery to inverter, inverter to charger etc). I am sure either me or my lady will forget to turn the charger off when on inverter. This complicates things a bit. How do we people avoid this? What is the best way to integrate a separate inverter and charger?

[stormalong]

Yes, you will need larger cables but they can be sized based on expected loads rather than peak inverter load provided that you put a circuit breaker in at the battery.

Example: You buy a 1 KW inverter but only intend to draw 500 watts max. You can size your cables for the 500 watts plus the overhead of the inverter (about 10% usually) as long as a circuit breaker is there to prevent drawing more than the 550 watts.

Also, there are many switching technology inverter/chargers that are lighter and smaller than the old style transformer based inverters.

When purchasing an inverter/charger you have to look at the peak load figure with some skepticism anyway. As said previously 1000 watts is over 80 amps at 12 volts. You probably don't want that kind of load for any length of time on lead acid batteries. Not driving the inverter that hard will probable extend it's life as well.

[Tenedos]

The biggest power draw is from my Nespresso machine. I know there are alternatives and I already have a manual nespresso machine I can use but nothing makes us happier than waking up and pressing a button to get our Espresso and Cappuccino. Those machines use up to 1250 watts for a short time. Maybe I should just give up on the idea...

[stormalong]

Originally Posted by Tenedos

I am trying to see if I can install a separate 1500w inverter, somewhere closer to the batter since it is smaller but then it sounds complicated to integrate it with the charger. Ideally I would like to connect the inverter to existing outlets and AC system but then it has a risk of causing a loop (shore power to battery, battery to inverter, inverter to charger etc). I am sure either me or my lady will forget to turn the charger off when on inverter. This complicates things a bit. How do we people avoid this? What is the best way to integrate a separate inverter and charger?

That's easy. You want a manual transfer switch to select shore power or inverter for your outlets. They work on a lockout basis - you can't have both on at the same time. The battery charger in not wired to the transfer switch, only to the shore power side. If you have an electric water heater you do not want to run that off of the inverter either.

[mitiempo]

I would never wire an inverter or inverter/charger with smaller cabling than its maximum output required. For a 2000 watt inverter that means 2/0 wire and a run of less than 5 feet.

As far as not leaving charger, water heater etc on when using the inverter/charger the best solution is to run the AC to the inverter from a breaker and wire the inverter output to a sub-panel that only only feeds the outlets.

How large is your battery bank? I would hope over 300 AH, 4 golf cart batteries being ideal.

I have always used 10% as the expected draw for an inverter - in other words 2000 watts draws 200 amps at max output. A bit high but it pays to be conservative in this case.

[Pete7]

Originally Posted by Tenedos

Ideally I would like to connect the inverter to existing outlets and AC system but then it has a risk of causing a loop (shore power to battery, battery to inverter, inverter to charger etc). I am sure either me or my lady will forget to turn the charger off when on inverter. This complicates things a bit. How do we people avoid this? What is the best way to integrate a separate inverter and charger?

We only plug mains voltage items directly into the inverter. The yacht's mains circuits are only live when plugged into shore power.

If you only want a couple of sockets, wire them separately from the inverter with a different colour socket so you know it's an inverter socket. For example at work we have red sockets that run off a bank and standby generator.

There was a huge debate about coffee on here a while back, but perhaps a french press would solve the problem rather than a coffee maker? or drink tea

[Tenedos]

Thanks a lot, lots of good suggestions.

Originally Posted by mitiempo

As far as not leaving charger, water heater etc on when using the inverter/charger the best solution is to run the AC to the inverter from a breaker and wire the inverter output to a sub-panel that only only feeds the outlets.

I like this idea. I looked at my wiring, this requires me to mess with the setup quite a bit. It is doable but basically I need extend the current outlet connection to the inverter and carry it back from the inverter.

Originally Posted by mitiempo

How large is your battery bank? I would hope over 300 AH, 4 golf cart batteries being ideal.

I have always used 10% as the expected draw for an inverter - in other words 2000 watts draws 200 amps at max output. A bit high but it pays to be conservative in this case.

I have two 210 AHs, a total of 400+. I agree with the DC cabling to be on the safe side and that is what worries me the most. Even if I choose a 1500W inverter, the closest I can bring it to is 6-7ft and that requires quite a bit of thick cables.

Originally Posted by Pete7

There was a huge debate about coffee on here a while back, but perhaps a french press would solve the problem rather than a coffee maker?

I am about to give up on the idea, however tempting it is... This project may need to wait for a bigger boat and I use my manual coffee machine until then...

[Quadrille in JB]

Over the past 20 years I've had 3-2,000 watt high end inverter/charger units fail. When 1/2 fails the entire unit is junk.
For the past 5 years I've used a Kisae 2kw pass through inverter with 2-50amp sterling chargers with Zero problems
Every thing runs through the inverter except the air conditioning.
The feed through feature automatically switches between shore power and inverter power. Its a no brainer.

[Tenedos]

I have one last test/attempt to do before I give up on this. I bought a standard 1500w inverter, nothing special. I also keep one of these on the boat in case I need to jump start the engine: 200Amp 12V car Jump Starter (21,000mAh)

I am thinking of testing the inverter with this battery, with obviously no connection whatsoever to the boat electrical systems except for a direct connection to the coffee machine.

21aH is not much but the coffee machine should not need more than 30 seconds of load. The peak power draw should not be an issue either. All in all, it probably won't work but I am planning to try anyways.

Any reason (particularly related to safety) why this is not a good idea to try?