Running aircon from 16A supply. More advice?

[boatmike]

The problem is the softstart has to be wired in such a way that is a mod to the OEM kit as supplied to any boatbuilder which i doubt they would be interested in as it's only a few cruisers that have this problem. Also it only really applies to chilled water systems as a multiple A/c install has seperate units/compressors so wouldn't normally be an issue. I have heard it can impact compressor life but i have never found a definite answer on that so i just use the softstart when needed which is very rare to be honest.

In fact when we started down here in 2001 we used to run the A/c for two months continously, got more used to the heat now & hate the shut in feeling so only run on days we are not cruising & if ultra hot with no breeze (like this afternoon!). Still we have lots of windows to open & all round white gauze blinds - which are the best thing ever, reduces the load on the A/c when it is running.

In fact my problem is my own fault for specing a single compressor chiller instead of a 2/3 compressor unit which would come on in stages reducing the draw. It's only occasionaly i can't get a 32A or two 16A feeds so not a big issue in Sof or Italy. By the way i would NEVER use the parallel 16A plug idea. For instance my marina uses different phases on sockets in the shore box. Big Bang, very dangerous. Wire something out to a seperate plug ie the chiller, much safer - anyway......

Talk to Dometic, they do supply softstart i believe. These days apparently its much better - there is a system that ramps the frequency up from 0 - 50Hz using a 3 phase chiller.

Having read this interesting thread throughout I think there is a need to restate the problem in simple terms. My own set up in a relatively small boat is a single 12000Btu self contained unit with "Smartstart" supplied by Dometic. The normal running load at 240v is 4 amps but the start up load (or in American Terminology Stalled Rotor Amps) is 28amps which would trip a 16 amp shore supply or be a problem with a small (4.5KVA) gennie or inverter. The Smartstart reduces the SRA from 28amps to about 13amps which would be within a 16amp shore supply and also allow a small inverter to run the aircon from the battery bank with sufficient alternator power (in my case 180 amps) with both engines running. While I hear all this stuff about increasing the shore supply by taking up two sockets it just ain't necessary if you keep to this kind of size of unit. If you have a greater need (which larger boats will) there is still a great advantage in fitting Smartstart which is supplied by Dometic for any of their units. The only reason boatbuilders don't fit it as standard is simply that owners don't specify it!

 

[Deleted User YDKXO]

Thanks Bart for comprehensive post

I assume the Victron power assist mode works to start your airco from 16A shore + extra power from the invertor ?

That is how I was given to understand it would work

- The max shore current is a setting that you should make yourselves, and can never be detected automatically. No unit can “see” how much current is maximum available.
Actually I never had a problem setting the max current at the NOMINAL current from the trip/fuse in the shore electric pole.

That was my mistake. Yes I assumed that detecting the trip setting was automatic but now I see of course that it could never do that and I will have to adjust it manually

This setting is something you need to change almost daily, so that extra “digital control” remote panel is almost indispensable for that;

Are you saying that I cannot make this setting from the VE Net controller?

If you want I can send you such a digital remote panel, (costs me less then 40 euro iirc)
Its really plug and play with a UTP cable.

Thanks for the offer and I may take you up on it but I'm going to review the whole system over winter when I take my boat back to Italy and can get a competent electrician. At the moment I can live with the way its set up and I don't trust Croatian electricians to mess around with it anymore

- Do you have a 3KW or a 5Kw unit ,
Remember a 3KW unit can only produce 13Amps in invertor mode, so you can never run your airco from the “invertor only” (your airco was 16A iirc ?)
Even if you have the 5Kw unit, (max 22A current invertor mode) might struggle with the startup current.

I have the 5kW unit

- The Victron can DEFO run on a Genny, I believe your supplier did wrong cabling of your unit,
Actually it is very simple, the unit should be cabled just “behind” the switch or relays that switches between shore or genny power supply.

OK thanks I accept this but as I say I dont want any more Croatian electricians messing around with my boat and I'll look at making this connection over winter

- The remote panel you have is handy for system settings and diagnostics, you can display all voltages and currents going in and out, … but not for daily display nor user settings

Again are you saying I can or cannot make the max shorepower current setting from the VE Net because the manual seems to say I can

I wouldn’t use it the way you do,
I believe you’d better put a soft start on your airco compressor, and then connect all the heavy 230V consumers; airco, boiler, dishwasher, washing machine, ice maker, desalinator, …on the AC2 output from the Victron.
This output doesn’t have the invertor nor power assist supply, it only works when shore power or genny power is available.

Yeah but surely the whole point of the Multiplus is that it augments with inverter power when the load exceeds the shorepower setting? Actually I dont have all the stuff you have. The only high load equipment I have is the aircon and boiler and I'm guessing those loads must be lower than on your boat. Agree though that soft start on the aircon is good idea

I had a hefty discussion with him about how to wire the Victron, Initially he didn’t want to do it like I asked, then two weeks later he came to excuse himself, and fully agreed with my setup, after reading and thoroughly investigating all features of the Multiplus.

I need to find somebody like that near Monfalcone this winter!

 

[Deleted User YDKXO]

Having read this interesting thread throughout I think there is a need to restate the problem in simple terms. My own set up in a relatively small boat is a single 12000Btu self contained unit with "Smartstart" supplied by Dometic. The normal running load at 240v is 4 amps but the start up load (or in American Terminology Stalled Rotor Amps) is 28amps which would trip a 16 amp shore supply or be a problem with a small (4.5KVA) gennie or inverter. The Smartstart reduces the SRA from 28amps to about 13amps which would be within a 16amp shore supply and also allow a small inverter to run the aircon from the battery bank with sufficient alternator power (in my case 180 amps) with both engines running. While I hear all this stuff about increasing the shore supply by taking up two sockets it just ain't necessary if you keep to this kind of size of unit. If you have a greater need (which larger boats will) there is still a great advantage in fitting Smartstart which is supplied by Dometic for any of their units. The only reason boatbuilders don't fit it as standard is simply that owners don't specify it!

Thanks for that boatmike. Since Dometic now own Condaria who manufactured my aircon unit, can I assume that they would approve the Smartstart for fitment to the Condaria? As you will have gathered, I am definitely not an electrical expert so I'm reliant on experts to tell me what can be done but this is something definitely worth looking at for me Actually I agree with you on the inverter running the aircon. At night we switch off all the air handlers except for the ones in any occupied cabins. When the system is stabilised close to the preset temp, according to the VE Net, the current draw is only 6-8A and I'm confident that my service batteries can handle that for a few hours

 

[boatmike]

Thanks for that boatmike. Since Dometic now own Condaria who manufactured my aircon unit, can I assume that they would approve the Smartstart for fitment to the Condaria? As you will have gathered, I am definitely not an electrical expert so I'm reliant on experts to tell me what can be done but this is something definitely worth looking at for me Actually I agree with you on the inverter running the aircon. At night we switch off all the air handlers except for the ones in any occupied cabins. When the system is stabilised close to the preset temp, according to the VE Net, the current draw is only 6-8A and I'm confident that my service batteries can handle that for a few hours

I am pretty sure you could retrofit a Smartstart but best to contact a competent dealer like Fischer Panda. They will be able to put you in contact with someone if you can't fit it yourself but it's pretty simple. As far as 6-8A is concerned be careful. I was talking about when underway with 180amp alternators replenishing the batteries. If that's 8 amps @240 volts then you need 8 x 240/12 = 160amps at 12 volts and for say 4 hours running that's 640 amp hours! (note that's a simple calc that ignores efficiency but near enough) I don't think your batteries would last long unless being boosted by an equivalent charge.....

 

[Deleted User YDKXO]

I am pretty sure you could retrofit a Smartstart but best to contact a competent dealer like Fischer Panda. They will be able to put you in contact with someone if you can't fit it yourself but it's pretty simple. As far as 6-8A is concerned be careful. I was talking about when underway with 180amp alternators replenishing the batteries. If that's 8 amps @240 volts then you need 8 x 240/12 = 160amps at 12 volts and for say 4 hours running that's 640 amp hours! (note that's a simple calc that ignores efficiency but near enough) I don't think your batteries would last long unless being boosted by an equivalent charge.....

Ah OK and yes you're right of course, boatmike, although my boat actually has a 24V system. I'll have to calculate my actual service battery capacity and make a judgement

 

[BartW]

Are you saying that I cannot make this setting from the VE Net controller?

I think you can, but it is not practical, you have to go in the menu,
Even with our small dedicated remote panel, we forget to change the max amp setting every now and then.

Yeah but surely the whole point of the Multiplus is that it augments with inverter power when the load exceeds the shorepower setting? Actually I dont have all the stuff you have. The only high load equipment I have is the aircon and boiler and I'm guessing those loads must be lower than on your boat. Agree though that soft start on the aircon is good idea

Well in that case, you can leave it all on the AC1 output, (Invertor)
you will have more invertor power available when the engine is running, to keep the boiler hot, and perhaps also for the airco, but you may not forget to switch off the Boiler nor Airco when you have no engines or genny running.
You also wouldn’t need the soft start then.
How many amps are the alternator’s on your main engine’s ?


Mike, believe me, you can NOT run your airco on the invertor only.
Even if you start the unit while the gen is running, (to cope with the start current)
Your airco consumes 8amps at 230V
Which is 77 amps at 24V
If you have a battery bank like mine, 600AH,
Wich you can empty only untill 80% , so use 20% of 600 is 120 AH,
Which means after 1,5hr your domestic battery’s would be useless ! (fridges and lights stop working !)

The invertor is usefull for low loads such a mobile phone chargers, computers, TV ,….

When the boat engines are running you have some more power available, depending on the capacity of the alternator. So then you can switch on the boiler and or the airco,
But this is all a lot of switching that you or your crew might forget !

 

[ARE]

Were you not offered the 5kW Victron Quattro Inverter/charger? this is the same as a Multiplus but does have two output, one for high current loads like A/C and boilers and is only avaialble with a shore or Generator supply, the second output can go to low power loads like lighting and sockets.

So if the shore supply gets disconnected while the air/con is running and you are away from the boat the inverter will not try and take the load. this does not effect the second lower power output from the Quattro that maybe powering lights or socket loads.

Anthony.

 

[BartW]

Were you not offered the 5kW Victron Quattro Inverter/charger? this is the same as a Multiplus but does have two output, one for high current loads like A/C and boilers

the Multiplus has also got two outputs (AC1 and AC2) for the purpose you explain,
but Deleted User's aim was to use the "power assist" function
which is mains + invertor power to start up the airco when mains power is limited to 16A.
This power assist function is only available on the "invertor" output,
not on the high load output, as explained in my earlyer post.


The quatro has indeed one extra input for the genny,
which make cabling more straight forward,
and
that genny / shore power / invertor power can all be managed from one system / remote

 

[John100156]

This looked interesting, not checked it out for size but might be worth taking a look....

http://www.britboatparts.com/domestic/heating/acssp.html

 

[Deleted User YDKXO]

I think you can, but it is not practical, you have to go in the menu,
Even with our small dedicated remote panel, we forget to change the max amp setting every now and then.

Bart, I have now read the manual(!) and played with the VE Net controller and actually it is quite easy to change both the max shorepower current and to change from inverter/charger to charger only. It involves scrolling through just 2 pages of the menu and editing the value. Even I can do that so now I'm happy using the VE Net controller

Well in that case, you can leave it all on the AC1 output, (Invertor)
you will have more invertor power available when the engine is running, to keep the boiler hot, and perhaps also for the airco, but you may not forget to switch off the Boiler nor Airco when you have no engines or genny running.
You also wouldn’t need the soft start then.

We don't use the aircon underway generally and if we do, we can switch the generator on. The way I intend to operate the Multiplus now is to leave it in charger mode all the time and only change it to inverter/charger mode when we are hooked up to a 16A supply. I have tested the Power Assist system with the shorepower limit set quite low and it seems to work fine and has no problem running the aircon even from start up although obviously I need to keep an eye on the battery condition

Mike, believe me, you can NOT run your airco on the invertor only.

Bart, yes having thought about it, yes of course you are right and I will be trying to avoid a situation in which the inverter tries to run the aircon by not leaving the boat with the inverter/charger mode on. Yes I will need to remember to make the change on the VE Net controller but I think I can get into the habit
As for the generator, that is still connected to the original Mastervolt charger fitted in the boat and I don't think this is a bad arrangement. If the Multiplus breaks down, I still have charging capability through the Mastervolt and gennie

 

[Deleted User YDKXO]

the Multiplus has also got two outputs (AC1 and AC2) for the purpose you explain,
but Deleted User's aim was to use the "power assist" function
which is mains + invertor power to start up the airco when mains power is limited to 16A.
This power assist function is only available on the "invertor" output,
not on the high load output, as explained in my earlyer post.

Thats correct, Bart. I did consider the Quattro but I only really wanted the Power Assist which the Multiplus had anyway