Inverter Wiring In line Fuse?

[muzbaz]

Hi,

Should an in line fuse be added to the live of the 12v feed to the inverter? (near to the battery)

 

I am going to fit a single pole isolator to the live feed to avoid standby power drainage but wondered if the unit needs to be fused

as well?

 

Bazza

[ranworthbreeze]

Hello Bazza,

 

I would fuse it but at what rating is yet another question.

 

Regards

Alan

[650xs]

err what size is yer inverter.....????

 

it will dictate the size orf fuse and main batt switch used too......

 

 

what doo yer need ole 240v for 

 

wife can blow dry hair doo while jogging along the bank .....

 

 

don,t use yer comput thinghy at all while on ole  water 

 

cooker boil kettle  with that new stuff .............gazz.....

 

 

and watch free sky tv ............how ...????

 

 

easy lay on back at nite out side on roof orf yer new greet ole huge boot and watch "sky tv ".....simples ...................!!!!!!!

 

 

orf my land ....................!!!!!!

[Guest]

Hi,

Should an in line fuse be added to the live of the 12v feed to the inverter? (near to the battery)

 

I am going to fit a single pole isolator to the live feed to avoid standby power drainage but wondered if the unit needs to be fused

as well?

 

Bazza

 

Yes, definitely. It draws a very large current when running, so needs it's own fuse, close to the battery as you surmised.

 

I would use a "mega fuse holder" for a domestic sized inverter, they can handle the current rating you need.

 

Because of the very heavy gauge of the Inverter's DC input cables, the fuse holder is connected using large compressible crimps, so you'll need to use the correct tool to fit them. (The normal hand crimpers aren't meaty enough).

 

As for the fuse size, divide the maximum output wattage by 12 volts to give the theoretical maximum amps draw, and then add a small percentage for the inverter's efficiency losses, so for instance, a 2000 watt inverter would be 166 amps, so that would be 200 amps.

 

Whatever you do though, don't fit a fuse larger than the input cable's current rating.

 

For safety and to comply with the BSS, make sure that no live parts are exposed with the lid snapped shut, which usually means putting some heat shrink sleeving over the crimp tails.

[Hockham Admiral]

Bazza, Hi.

 

You won't go far wrong if you follow Strow's excellent advice above... :clap

 

But you really do have to look at the condition of your domestic battery befort you start drawing the sort of loads you might incur. As Strow says, you can draw a lot of current and 10-15 minutes at that sort of load will soon flatten, if not deaden, your battery...  :cry

[Mowjo]

Sorry I can't help on this one at all! but I have a question! I know what inverters do, but why would you need one on a boat, the only reason I can think of is for things like hairdryers and microwaves, seems a lot of trouble to warm your pies up, I have two 110 amp domestic batteries, I run an 65ltr Isotherm  fridge, two laptop computers, 12v hairdryer all my lights, charge phones and two tablets, plus the usual water pumps and general boat stuff and never had a flat battery, so I can't work out why anyone would actually need an inverter,,

 

Frank,,,,, 

[littlesprite]

I can't work out why anyone would climb Everest.

 

Variety is the spice of life, if everyone was the same it would be a boring world 

[muzbaz]

Thanks for the replies

 

Ok,,

 

The inverter is a 1500w continuous 3000w surge Pure Sine Wave unit,

Strowager,,the conversion you gave to obtain correct fuse protection, would that be the max power including surge (3000w)?

The Mega Fuse Holder you supplied an image of is something I had seen but wasn't sure it was what I needed, as usual the internet image doesn't give the presence like seeing it on the shelf. 

I intend to measure out distance from battery bank to inverter hidey hole and obtain correct size (length gauage and current handling) cable pre crimped as you say your DIY crimping tool isn't up to the job.

 

The need for an inverter Mowjo is not essential but really a luxury, the maximum I can envisage it being needed for is the things my wife wants to plug in, she has many toys the largest is possibly her hair dryer which is 1200w and really only on for 5-10m. Yet obviously it can't run the hair dryer AND an 800w microwave, but that problem is covered as the wife is unlikely to dry her hair while nukeing the frozen mash, even though she can multi task! as she constantly reminds me :-D

If we are moored al fresco and want to power such toys then an inverter will save the day,,, little 12v driers don't cut the mustard,, you haven't seen my wifes hair!! 

 

We have always managed on 12v on boats in the past but again intend to install a 240v system to use shore power when we want, just to have the luxury I guess.

 

Thanks HA John the cells have yet to be analysed, we do however have an allocated budget for 3 new deep cycle cells and a new cranking battery should none of the present ones be usable.

 

Strowager for your advice as above please

 

Regards to all

 

Bazza

[BroadScot]

And to think we use to solder those ends not crimp them lol Maybe 50 years ago it was the modern thing to do! lol

[Mowjo]

Thanks Bazza! I wasn't being negative about them, no pun intended  I just couldn't work out why they were needed, when we have good 12v and most of us now have 240v, but as you mention wild mooring it kind of makes sense, we do a lot of wild mooring but I'm not telling the Mrs about inverters, I'll just buy her a beany hat to hide her hair,,,,

 

Frank,,,,

[Guest]

......Strowager,,the conversion you gave to obtain correct fuse protection, would that be the max power including surge (3000w)?.....

 

 

No, that was for 2000w max.

 

If your inverter can surge up to 3000w then the fuse needs to permit that, so it would be 3000 / 12v =  250 amps, 

 

I believe the next size fuse up from that is 300 amps, so I think in this case I'd stay at 250 amps, as it's just for surges.

 

 

That is indeed a huge current, so even with a big battery bank of say three x 120 amps, it would reduce it from full capacity to half in just about 45 minutes.

 

If you're getting the shop to do the crimps, don't forget to ask them to heatshrink the crimp ferrules as well, so much neater than tape !

 

Re the post about soldering crimp connectors instead, it is very much frowned upon in high current wiring because it literally falls apart if it overheats, whereas crimps do not.

 

Here's the Mega fuse range and prices on the ASAP website at Beccles:

http://www.asap-supplies.com/search/mega+fuse

[muzbaz]

No Negative vibes received here Mowjo 

 

Strowager I couldn't think of that simple word 'formula' I should have said formula not conversion,,, anyway,

you've now saved me dusting off the abacus too,

The heat shrunk ferrules will be something more presentable than tape and I will make sure the cables are correctly rated too, the battery isolator that I have is rated to 450amps so it looks like I am there with the requirements for a safe install, the cells priced up are 135aph.

We went to the boat show on Sunday and bought a solar panel regulator etc to keep the battery bank topped up while away from the boat and was really happy with the price, the show was very interesting to us as we have learnt so much over the last couple of years, but I couldn't understand while my card was declined when I tried to purchase a 40 million pound yacht 

[BroadScot]

Strow I can assure you IT was the done thing to solder with a gas gun and molten tin solder to heavy single core VIR wire connecting to a BusBar Chamber in 1965. I agree that today it would be frowned upon.

[Guest]

Strow I can assure you IT was the done thing to solder with a gas gun and molten tin solder to heavy single core VIR wire connecting to a BusBar Chamber in 1965. I agree that today it would be frowned upon.

 

My avatar is a telephone dial because I did a three year apprenticeship with the GPO, (as it was then known), in the 60's.

 

Soft soldering, silver soldering, lead plumbing sheath closures.

 

Still got the bl**dy scars.....  

[BroadScot]

I am just about to officially retire as a Electrician this friday. We were given pig skin gloves doing that job, I remember some of the young lads getting the odd burn scar.   A mate of mine started as an apprentice with the trusted GPO but came over to my trade, more money! lol. Oh and of course not like now, a 5 year apprenticeship. Ah happy days.

[ranworthbreeze]

I came out of the trade at 25 because my boss would not pay the extra 2p per hour from £1.23 to £1.25 per hour for the approved electrician rate, the JIB sold everyone down the river before that of course prior to that.

 

Most of other apprentices I ran into at college were fearful of their jobs, at the time in Sheffield it was common practice for some firms to fire apprentices after serving their time rather than making them up.

 

4 years working in the amusement industry, it could have been worse I could have accepted the job as works engineer for a kitchen manufacture company. In 1981 I became self employed and have been working unpaid for the government ever since.

 

As you say happy days, still working, just! and everyone seems to be retiring but they won't let me join the club. 

 

Regards

Alan

[BroadScot]

When we were graded I was made up to Technician, my boss said no way am I paying you and extra 9d an hour. Rather than lose my job, I was regraded to Approved Lecky. As it happened our foreman left for more money elsewhere, and I got his job with an extra 1/- an hour think it was. Just crazy that SJIB idea, so many left the trade because of it. 1983 I was made redundant as my boss retired. So I too been self employed ever since. But due to health reasons not worked full time in years.

The good bit though, it meant I could drive down from Scotland three times a year to have my Broads fix! My wife being a teacher found it a great way to chill out! Sorry for going off topic. Hope you get your fuses sorted out ok.

[muzbaz]

Ha Ha,,, off topic is good when it's interesting 

 

I have received my battery isolator today and the fuse and holder have been dispatched

so once I get the chance to measure up I can order my cabling.

[kfurbank]

Slightly different subject, but have you given any consideration to how your going to recharge the batteries. As has been pointed out even with three batteries, an invertor of that size will soon drain them. However when it comes to recharging them, you are going to need to do a lot of engine hours. Do you have a split diode setup to separate the charging of the engine battery from your domestic setup? More importantly it stops you discharging the engine battery when discharging your domestic batteries. What size if the alternator? Most only give full output at a decent rev limit. If pottering up and down the Ant, they will probably be at about half output. If your domestic battery bank is 405 amps, even half flat an alternator running at say 40 amps output is going to need some hours to recharge. More and more boats with large domestic battery banks are looking at twin alternator setups. This is the standard setup on a lot of the Barnes hire boats.

 

My own has both 12V and 24V alternator. 2 x split diodes, one for 12V and one for 24V and six batteries.

[muzbaz]

I fully appreciate the load the inverter would put on the battery bank if used as a continuous power source for multiple items. As you suggest being able to replace the charge from a single alternator is a challenge so consideration to introduce a second alternator is one possibility.

 

I have looked at a product from Sterling which digitally manages the output from the alternator:

 

http://www.sp-shop.co.uk/Sterling-Power-Digital-Advanced-Alternator-Regulator.html

 

Or if that isn't ideal then a alternator to battery charger might be the way to go:

 

http://www.sp-shop.co.uk/Sterling-Power-Alternator-to-Battery-Charger-12V-80A.html

 

All things considered the inverter is only a luxury as up to now our demand for 240v when not connected to shore power is very minimal and then we just manage.

 

The boat will have a 50w solar panel producing up to 3 aph to trickle charge the cells when we are away from the boat and this has worked well in conjunction with the engine alternator and simple 12v usage in the past.

 

I watched a video that highlighted the current from alternators during normal cruising speed/revs and as you say at normal cruising you aren't always utilising the power available from the alternator, it made interesting viewing.:  

http://youtu.be/GRCrRwOi6_8 

 

Your thoughts on any of the products above are most welcome 

[Guest]

......I watched a video that highlighted the current from alternators during normal cruising speed/revs and as you say at normal cruising you aren't always utilising the power available from the alternator, it made interesting viewing.:......

 

 

Quite right, many alternators fitted in boats are not being run efficiently.

 

So many people fit two, or even three alternators to increase the charging output when the original single one can usually  have it's ouput significantly increased.

 

The alternator's output is normally controlled by it's own built-in controller, which can switch the charging coils in and out to increase the charging current without needing increased revs, just like when fitted to cars, unlike the old fashioned dynamos, where the output was always directly proportional to the revs.

 

Many controllers don't take advantage of this though, because they still follow the charging model needed by cars, where they give a strong charge just after starting, which then quickly reduces after it thinks it has replenished the amps used for starting. Boat usage is quite different though, where the deep cycle batteries are run down significantly while the engine is not running, something that doesn't generally happen with car batteries..

 

You can therefore get much higher charging rates from the original single alternator if you fit an intelligent controller specifically designed for boats.

 

I fitted the Sterling SplitR to my boat, which combines several devices in one small unit. It is an intelligent controller, maximising charging output while pulse monitoring battery levels, and also gives the advantage of split charging to two batteries, but without the volt drop problem of diode splitters. They do a three battery version too.

 

My batteries can now receive maximum (55 amp) charging rate at quite low revs, replenishing the deep cycle auxiliary very quickly, then dropping back to trickle charge.

[muzbaz]

 

I fitted the Sterling SplitR to my boat, which combines several devices in one small unit. It is an intelligent controller, maximising charging output while pulse monitoring battery levels, and also gives the advantage of split charging to two batteries, but without the volt drop problem of diode splitters. They do a three battery version too.

 

 

Strow,

When the unit says it will supply split charging to 2 batteries, would that be to 1 cranking battery and 1 liesure, or does it class the bank of domestic cells as one large battery and then the cranking battery as the 2nd? the reason for this question is we have 3 domestic and 1 cranking so will and how would the 2 or 3 battery version serve my set up? 

[Guest]

Strow,

When the unit says it will supply split charging to 2 batteries, would that be to 1 cranking battery and 1 liesure, or does it class the bank of domestic cells as one large battery and then the cranking battery as the 2nd? the reason for this question is we have 3 domestic and 1 cranking so will and how would the 2 or 3 battery version serve my set up? 

 

 

I use the two battery model on my boat for one cranking battery and one deep cycle auxiliary.

 

They do three and four battery ones as well.

 

http://www.sterling-power.com/images/downloads/pro-split-r-eng-ger-fre.pdf

 

http://www.norfolkmarine.co.uk/shop-online/marine-electrical-sterling-power-c-1036_1174-page-2.html?page=2&sort=3a

[Mowjo]

Bazza! looking at Strows links it looks to me like it's banks of battery's, because I'm good at looking at pictures but not reading stuff, the 3 battery is supplying 1 Starter and 2 banks of battery's, and the 4 battery shows as 1  starter and 3 banks of battery's, if you look at the Sterling link, it shows the 3 battery supplying 1 Starter, 6 main domestic and 3 general battery's, that's a lot of battery's my waterline would drop at least 1ft with that lot, think I'll stick with my 20 mile extension lead, only trouble with that is I have to keep returning to my moorings to top the leccie up,,

 

Frank,,,

[mbird]

I fitted one of those to my first boat, which had three banks of batteries (so I fitted the 3 battery one). My banks were; 1x starter, 1x dedicated inverter battery, 2x domestic batteries. Seemed to work very well indeed.