Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 02-12-2014, 21:12   #16
Senior Cruiser

Cruisers Forum Supporter

Join Date: Nov 2005
Location: Out there doin' it
Boat: 47' Olympic Adventure
Posts: 2,634
Re: Inverter for 4 ring Induction Domestic Hob?

Dashew switched to induction - you might post a comment here with your question(s): SetSail » Blog Archive » Efficient Electric Cooking Part 1
__________________

__________________
Lodesman is offline   Reply With Quote
Old 02-12-2014, 21:16   #17
Registered User
 
deckofficer's Avatar

Join Date: Feb 2011
Location: Northern and Southern California
Boat: too many
Posts: 4,198
Images: 4
Re: Inverter for 4 ring Induction Domestic Hob?

If your planning on cooking via inverter and lead acid batteries, I agree with the above posts. Induction is a great way to cook with gen set or shore power, but due to peukert effect and voltage sag of lead acid batteries, I don't think it will fly. If you had a LiFePO4 battery bank and 48 volt inverter you would be good to go.
__________________

__________________
Bob
USCG Unlimited Tonnage Open Ocean (CMA)
http://tbuckets.lefora.com/
deckofficer is offline   Reply With Quote
Old 03-12-2014, 00:50   #18
Registered User

Join Date: Jun 2013
Location: canada
Posts: 1,696
Re: Inverter for 4 ring Induction Domestic Hob?

if you're trying to get 5000 w for (a 4 element stove, no idea what a ring or hob is...), run the gen for 10 mins while cooking...


an inverter that big just for that would be silly
__________________
smac999 is offline   Reply With Quote
Old 03-12-2014, 01:33   #19
Registered User

Join Date: Oct 2014
Location: Sussex UK
Boat: Unique 1400 14M
Posts: 85
Send a message via Skype™ to brightontrader
Re: Inverter for 4 ring Induction Domestic Hob?

Thanks to all posters, lots of views.

I have already installed the whirlpool 4 ring cooker top, so committed.

The previous cooker ran on one ring only on inverter, my thinking is that with this system I can run 2, total load 3.8kw, and still have other items such as PC, fridge etc running concurrently.

Having an induction at home for 2 years I know how I use it: On induction you only use full power rarely as its so powerful you burn the bottom if not just water in pan, then simmer at around .6 power setting...I have a relatively low power electric kettle for tea/coffee...

So 2 x rings = 3.8x.6 =2.28kw plus some more on start up...The 4 rings would only be used on SP, ie: most of the time when the wife is on board messing up the galley.

Reality is you do not necessarily use a cooker for long periods if you have a microwave/combi oven (I have), fry some fish, veggies on another ring, (full english breakfast takes 10 mins to fry up) how long is that? 25 mins max...Bread making is in oven, same for stews (man food at sea).

As I have posted, when actually passage making have 30amps coming from Prop alternator continually under sail, 50amps from engine if motoring. If at anchor then the issues come into play, then I do have a generator albeit only 6.5kw.

How much loss does a 5000w 24v mastervolt do. Its supposed to be 91% efficient. What does this really mean? And is there a lot of power used when idle?

Anyway, have put a bid in now on ebay, if I win it will mean a cheap expensive 5kw quality inverter. If I lose will get hold of 3.5 or 4kw one to run 2 rings. I have a source of very heavy duty deep cycle batteries made for US Army tanks, hoping to get 2 shortly as a gift, seconds, ie rejects due to scratches apparently.Boat is presently under batteried anyway.

Really I should have gone back to gas but boat I have bought has never had gas and fitting it is problematic....

This yacht, a steel dutch built one off, 46' on deck, 40' waterline, has the space for more batteries and large inverter, its not a racing boat, its a go anywhere cruiser. I bought it for a good price (I think) and am prepared to spend some on it getting it right and going for new approach equipment is a risk but also I have spent 6 yrs cruising off grid before (15 yrs ago) so do know how I use stuff. I also spent most time when not actually passage making in marinas even in places like Phuket, going out into Pangna bay with guests for a week at most off grid. In Europe, the Med, its hard to even find anchorages as most good ones have been developed into marinas anyway (Spain)!!!!

Wonderful thing about this is can flog mistake purchases on ebay, am changing out 10 yr old Lowrance radar and chartplotter for Raymarine kit and new autohelm already, will ebay off old kit soon. Its winter here, the boat is in a marina presently, will try unhooking shorepower for a while and try systems for a couple of days, see how it goes.
__________________
brightontrader is offline   Reply With Quote
Old 03-12-2014, 03:43   #20
Registered User
 
transmitterdan's Avatar

Join Date: Oct 2011
Boat: Valiant 42
Posts: 4,019
Re: Inverter for 4 ring Induction Domestic Hob?

Efficiency of inverters is measured from input terminal to output terminal. You can never achieve that in a boat unless all your cables are zero length. I see too many inverter installations where the DC wires are too small and/or long thus efficiency is significantly reduced. If you do the math and use wire big enough to not significantly reduce efficiency you might be able to achieve 85% efficiency. But you may be surprised how big the wire has to be. At 5000W and 24V the RMS battery current is about 250A. The wire size will be huge (12mm minimum and preferably 15mm) for even a 1M length. And it would be even larger for longer runs. Most inverters will not accept large enough wire so creative installation is required.
__________________
transmitterdan is online now   Reply With Quote
Old 03-12-2014, 04:09   #21
Registered User

Join Date: Oct 2014
Location: Sussex UK
Boat: Unique 1400 14M
Posts: 85
Send a message via Skype™ to brightontrader
Re: Inverter for 4 ring Induction Domestic Hob?

Dan, very good point, thanks.

May have to go to much smaller inverter from comments on here, like a 2.5kw to 3kw and if I win ebay auction 5kw use for small hydro am installing on a weir or re sell it,,,,,,auction is in 4 hours, have put in a minimum bid..oh dear..

I also remember reading that inverters run best on near full load and if over specified waste a lot..
__________________
brightontrader is offline   Reply With Quote
Old 03-12-2014, 05:30   #22
Registered User

Join Date: Mar 2014
Posts: 225
Re: Inverter for 4 ring Induction Domestic Hob?

Quote:
Originally Posted by sea-bee View Post
Our house is off grid, with about 2000w solar and 400AHr LiFePO4 batteries. On these hot summer days we have excess power, and use a single induction hotplate for quick cooking off the inverter. Draws about 100 amps.

Chris
Chris, check your numbers. My 1800W induction hob draws less than 15 amps at full power.

I only use full power to quickly boil water; when I say "quickly", only other induction hob users know what I'm talking about. After the water reaches boiling, the power is lowered to 10% or 20% to maintain a simmer. I never cook anything at higher than 30%.

Brightontrader, I'm sure you are aware that any one of the coils on your hob cannot draw the full 7.2 kW and even with two coils active at 100%, you will probably not draw 7.2kW. Different manufacturers have different ways of distributing the power. You mentioned you don't have the distribution information on your unit; you might find it here:
The Induction Site: Whirlpool Induction Hobs

Meanwhile, to get to your inverter question, think about how you will really use the hob while asea. I doubt you will ever use all four zones simultaneously. Let's say you would use a small one at 100% and a large one at 30%. Then, put a pan of water on each and fire them up accordingly. Use a multimeter to measure your actual current draw. That will help you accurately size your inverter.

Good induction electrical requirement primer here: Induction Cooking: Kitchen Electricity 101
__________________
jwing is offline   Reply With Quote
Old 03-12-2014, 06:12   #23
Registered User
 
transmitterdan's Avatar

Join Date: Oct 2011
Boat: Valiant 42
Posts: 4,019
Re: Inverter for 4 ring Induction Domestic Hob?

Jwing,

Chris is talking about battery amp draw when he mentions 100A. You have to be careful when discussing amps to know whether it is the AC side or the DC side. As a general rule of thumb in 24V systems the DC current is 6 times higher than the AC. So your 15 amps AC becomes 90A DC. For 12V systems the DC current is 12 times more than AC.
__________________
transmitterdan is online now   Reply With Quote
Old 03-12-2014, 06:26   #24
Senior Cruiser
 
atoll's Avatar

Cruisers Forum Supporter

Join Date: Mar 2010
Location: gettin naughty on the beach in cornwall
Boat: 63 custom alloy sloop,macwester26,prout snowgoose 37 elite catamaran!
Posts: 9,311
Images: 75
Re: Inverter for 4 ring Induction Domestic Hob?

Quote:
Originally Posted by transmitterdan View Post
Jwing,

Chris is talking about battery amp draw when he mentions 100A. You have to be careful when discussing amps to know whether it is the AC side or the DC side. As a general rule of thumb in 24V systems the DC current is 6 times higher than the AC. So your 15 amps AC becomes 90A DC. For 12V systems the DC current is 12 times more than AC.
I think his cooker is 240 volts ac,not 110volts ac,so the draw would be;

24vdc-240vac=10x

12vdc-240vac=20x
__________________
my catamaran building project updates http://www.cruisersforum.com/forums/...36#post2502136
atoll is offline   Reply With Quote
Old 03-12-2014, 07:01   #25
Registered User

Join Date: Jul 2012
Location: Switzerland
Boat: So many boats to choose from. Would prefer something that is not an AWB, and that is beachable...
Posts: 1,241
Re: Inverter for 4 ring Induction Domestic Hob?

Is it single phase 240V? Most larger induction cookers sold in Europe are actually set up for 3 phase 400V. You would then need three inverters in parallel. However it would solve the problem of getting enough power.

You probably need an inverter with power assist. You won't often run your hob at full power. But when you do your generator will be used to provide most of the power, and the inverter only needs to add the balance. A Victron Multiplus for example.
__________________
K_V_B is offline   Reply With Quote
Old 03-12-2014, 07:12   #26
Registered User

Join Date: Oct 2014
Location: Sussex UK
Boat: Unique 1400 14M
Posts: 85
Send a message via Skype™ to brightontrader
Re: Inverter for 4 ring Induction Domestic Hob?

Jwing, very useful links....both of them. I do have the 1st Whirlpool cookertop, albeit a different layout (and only paid $377 new not $1000+) prices have obviously come down a lot since that was written.

I see that I could get by with my current inverter (Victron 1.5) for the one ring (1.4kw) which is exactly what I had before (ceramic) with the complicated power management system. Now have ditched that and am already better off as it worked intermittently.

The 30amp wiring to ring main was already in place as the ceramic on all 4 rings on full used 7kw, will take my chances on on 7.4kw on 30amp circuit (240V) as cannot think will ever use all 4 on full blast. (may print a neat sign to warn as much and put by cooker!) 2nd link from Jwing told me needed 30amp for 7.2 but also said that could probably get away with it if appliance used 7.4 as will never use all 4 on full power...so sorted...(At least on SP, if there is a fire can simply step ashore and call the insurance company

So, very pleased posted questions as replies have given me answers I needed, very quickly and now know that the induction change out from ceramic is worthwhile and do able, with maybe a slightly bigger (3kw) inverter with a overload cutout switch. Will give me 2 rings off grid on batteries and all 4 on SP obviously,.maybe 4 on genny...

now does anybody want to buy a 5kw Mastervolt Dakar Pure sine.....going very cheap//$1185
__________________
brightontrader is offline   Reply With Quote
Old 03-12-2014, 07:20   #27
Registered User

Join Date: Oct 2014
Location: Sussex UK
Boat: Unique 1400 14M
Posts: 85
Send a message via Skype™ to brightontrader
Re: Inverter for 4 ring Induction Domestic Hob?

KVB, you are writing concurrently with me.

Its a domestic Whirlpool, single phase....I had 3 phase in my factories, haven't thought of 3 phase on boat, I don't think marinas would supply it apart from to superyacht berths maybe.

Mine is a superyacht, to me anyway..
__________________
brightontrader is offline   Reply With Quote
Old 03-12-2014, 08:01   #28
Registered User
 
transmitterdan's Avatar

Join Date: Oct 2011
Boat: Valiant 42
Posts: 4,019
Re: Inverter for 4 ring Induction Domestic Hob?

Quote:
Originally Posted by atoll View Post
I think his cooker is 240 volts ac,not 110volts ac,so the draw would be;

24vdc-240vac=10x

12vdc-240vac=20x
Atoll,

You are probably right about the 240V (hob should have given it away). But since the inversion process is not 100% efficient I like to plan for about 20% more current to make up for inefficiencies in inverter and wire. So DC current would be 12X (24V) and 24X (12V) as a better rule of thumb for 240V inverter systems. Thanks for correcting my mistake.
__________________
transmitterdan is online now   Reply With Quote
Old 03-12-2014, 08:14   #29
Registered User

Join Date: Mar 2014
Posts: 225
Re: Inverter for 4 ring Induction Domestic Hob?

Quote:
Originally Posted by transmitterdan View Post
Jwing,

Chris is talking about battery amp draw when he mentions 100A. You have to be careful when discussing amps to know whether it is the AC side or the DC side. As a general rule of thumb in 24V systems the DC current is 6 times higher than the AC. So your 15 amps AC becomes 90A DC. For 12V systems the DC current is 12 times more than AC.
Thanks for the clarification!
__________________
jwing is offline   Reply With Quote
Old 03-12-2014, 09:29   #30
Registered User
 
ryon's Avatar

Join Date: Feb 2013
Location: Southern California
Posts: 588
Re: Inverter for 4 ring Induction Domestic Hob?

I could go on with my list of reservations, but it seems to be working for you and that's what's important. You make a point about pure sine wave inverters, and those shouldn't be necessary in this application at all. A dirty square wave or whatever should work just as well.
__________________

__________________
ryon is offline   Reply With Quote
Reply

Tags
inverter

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
induction hot plates running off inverter. sparrowhawk1 Product or Service Reviews & Evaluations 1 01-03-2014 14:10
"Stand Aside" Skipper Syd-Hob 1998 s76640 General Sailing Forum 5 13-01-2013 18:14
Diesel hob rocma Provisioning: Food & Drink 5 05-03-2011 13:37
Domestic Disturbance boats... shadow Monohull Sailboats 6 29-09-2008 12:23
Generator - marinised or domestic Ricky Electrical: Batteries, Generators & Solar 1 19-08-2008 04:50



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 15:10.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.