inverter connection

[colin loach]

Hi all. I Want to install a 1000 watt inverter on my boat, what is the best way to do this. Do I go from the batteries to a fuse block and then to the inverter, or from the batteries straight to the inverter. Also what is the best way to connect the batteries to the fuse holder, do I go through some sort of connecting block first on the plus side and neg side. Dose anyone have any pictures or drawings. Thanks Colin.

[DHutch]

Hi, colin.

 

Its usuall to incorporate a fuse between the inverter and the batterys. Often using a dedicated fuse/isolator rather than taking the supply through or from the main fuse/distro board, which often isnt upto the job of supplying such a high current device (1000w at 12v is around 100amps or more).

 

Its also very much advised to keep the cable length to an absolute minimum as well, for the sake of cost (you need thick wire) and voltage drop (which loops back to needing thick wire).

 

Theres loads of simular topics to this if you do a search, and the inverter should come with some form of installation instuctions. However maybe this will help for now.

 

 

Daniel

[colin loach]

Hi Daniel, should I put the fuse near the batteries or the other side of the bulk head near the fuse box, and have you any suggestions what sort of fuse board I should buy.

[stuart]

Hi Daniel, should I put the fuse near the batteries or the other side of the bulk head near the fuse box, and have you any suggestions what sort of fuse board I should buy.

 

Both have been covered plenty of times before, have a search!

 

The fuses generally go near the battery - they protect the cable not the inverter.

[pagan witch]

2 things here . . . .

 

1) Without wishing to sound unhelpful if you are not sure about wiring one of these up then don't. You are almost certainly connectiong up to a bank of at least 3 batteries at 110 Ah each with enough raw power to do some serious damage - remember you can easily weld with 40A and if you manage to short these out accidentaly that's what you'll be doing. Burns are a real danger here.

 

2) If despite this you wish to proceed then please make sure the neg connection goes through a battery isolator - not doing so is a pretty quick way to fail your BSS. This can be either a seperate isolator to the boats' other systems or can share the same one but remember to check the current rating of the isolator. A 2kw inverter at full whack is around the 200A mark.

[steelaway]

Hi all. I Want to install a 1000 watt inverter on my boat, what is the best way to do this. Do I go from the batteries to a fuse block and then to the inverter, or from the batteries straight to the inverter. Also what is the best way to connect the batteries to the fuse holder, do I go through some sort of connecting block first on the plus side and neg side. Dose anyone have any pictures or drawings. Thanks Colin.

 

Hi Colin

 

Have a look at this fuse holder on ebay -- Midi / Strip Link Fuse Holder Box with 100 Amp Fuse TVR

You need to fit something similar in the live cable to your inverter.

You will need a 150 amp version from a chandlers and cable (Red & Black) of at least 16mm.

Plus cable lugs to fit the cable and connections. (16mm cable/ 8mm holes?)

You may have to borrow a cable crimper or have them made up at good motor factors.

Take the red direct from your battery's isolating switch to the fuse and then onto the inverter.

Return with the black wire to the battery's.

 

Alex

[Nickhlx]

What size cable (CSA) is needed with the 3KVa sine wave inverters then - must be massive ?

 

Nick

[Dylan]

What size cable (CSA) is needed with the 3KVa sine wave inverters then - must be massive ?

 

Nick

I believe that the cables supplied with my Sterling 3kW are 75mm sq (2 metres long) but I would need to double check that.

[chris w]

Hi all. I Want to install a 1000 watt inverter on my boat, what is the best way to do this. Do I go from the batteries to a fuse block and then to the inverter, or from the batteries straight to the inverter. Also what is the best way to connect the batteries to the fuse holder, do I go through some sort of connecting block first on the plus side and neg side. Dose anyone have any pictures or drawings. Thanks Colin.

 

Colin

 

You need a fuse in both the positive and negative cable. You do NOT need an isolator to pass the BSS (in fact it would add additional loss) but you DO need the fuses. Wire the inverter DIRECTLY to the batteries through these fuses. (150A fuse in each cable) for a 1000W inverter. You can buy these large fuses in holders for about £20 each. The cables connect to them via crimped-on ring terminals.

 

Cable length should be a minimum, preferably no more than 1 metre. Volts drop on the cables should be lower than for nornal wiring to avoid the inverter's dropping out due to low voltage when other devices are also drawing significant current. For a maximum drop of 0.2v over 1 metre (ie: 2 metres round trip total) you will need 20mm² cable for a 1000W inverter.

 

For a distance of 2m between the battery and the inverter (ie: 4 metres round trip) you would need 40mm² cable.

 

Chris

[Nickhlx]

Thanks for the info - I don't think I have ever even seen 75mm cable ! But I suppose its what connects onto car batteries as the starter motor probably takes around 300 to 500 amps

 

Nick

[Gibbo]

You need a fuse in both the positive and negative cable.

 

 

??????????

 

Gibbo

[stuart]

??????????

 

Gibbo

 

 

Seems over kill to me too! Why 2 fuses Chris?

[chris w]

Seems over kill to me too! Why 2 fuses Chris?

 

 

The fuse in the negative line is to protect against your accidentally connecting up the positive and negative cables the wrong way round. The fuse in the positive line is to protect the cables in the normal way.

 

Chris

[Gibbo]

The fuse in the negative line is to protect against your accidentally connecting up the positive and negative cables the wrong way round.

 

 

??????

 

Gibbo

[ChrisPy]

The fuse in the negative line is to protect against your accidentally connecting up the positive and negative cables the wrong way round. The fuse in the positive line is to protect the cables in the normal way.

 

Chris

yeah, well ..........................

[steelaway]

yeah, well ..........................

 

 

Ditto

[colin loach]

Hi All. Thanks for all the information I have just got back on the computer, been away for a few days. I’m going to fit a 1000 watt inverter and a 300 watt inverter to run the TV DVD and cooker fan, the 1000 watt is just for tools and hair dryer. I’m going to run 150 amp cable from the battery to the isolator with a inline fuse connected on the positive. From the isolator I will go direct to the switched fuse box buzz bar and then to both inverters. The neutral will be connected from another buzz bar and go back to the negative on the battery. Both inverters will be protected by a r.c.d. which in turn protects me from getting a 240 volt shock. I have got 12v white led lighting, two pumps and a small amp for the Arial coming from the same fuse box, my other fuse box works the horn, headlight and navigation lights and is connected to my starter battery. By the way the boat is a sail away from lb so I have got a lot to do, any advise will be welcome. Colin.

[chris w]

Hi All. Thanks for all the information I have just got back on the computer, been away for a few days. I’m going to fit a 1000 watt inverter and a 300 watt inverter to run the TV DVD and cooker fan, the 1000 watt is just for tools and hair dryer. I’m going to run 150 amp cable from the battery to the isolator with a inline fuse connected on the positive. From the isolator I will go direct to the switched fuse box buzz bar and then to both inverters. The neutral will be connected from another buzz bar and go back to the negative on the battery. Both inverters will be protected by a r.c.d. which in turn protects me from getting a 240 volt shock. I have got 12v white led lighting, two pumps and a small amp for the Arial coming from the same fuse box, my other fuse box works the horn, headlight and navigation lights and is connected to my starter battery. By the way the boat is a sail away from lb so I have got a lot to do, any advise will be welcome. Colin.

 

1. What do you mean by 150A cable? What cross-sectional area is it?

 

2. What is the distance between the battery and the inverter?

 

3. To allow the RCDs to operate and give you protection you MUST:

 

(i) connect the hull to the battery negative

 

(ii) connect the mains earth to the hull close to the battery negative hull connection

 

(iii) connect the mains neutral and earth on the inverters together (some inverters already have this done when supplied but do check)

 

The RCDs will not operate, in the event of an earth fault, if you don't do all three things above in part 3.

 

4. You should install a separate fuse for each inverter rated at 150A for the 1000W and 50A for the 300W

 

5. I would not mix the inverters and other circuits on the same busbar.

 

Chris

[colin loach]

1. What do you mean by 150A cable? What cross-sectional area is it?

 

2. What is the distance between the battery and the inverter?

 

3. To allow the RCDs to operate and give you protection you MUST:

 

(i) connect the hull to the battery negative

 

(ii) connect the mains earth to the hull close to the battery negative hull connection

 

(iii) connect the mains neutral and earth on the inverters together (some inverters already have this done when supplied but do check)

 

The RCDs will not operate, in the event of an earth fault, if you don't do all three things above in part 3.

 

4. You should install a separate fuse for each inverter rated at 150A for the 1000W and 50A for the 300W

 

5. I would not mix the inverters and other circuits on the same busbar.

 

Chris

I am not sure of cable size I was going to ask in the shop, but the run will be about a metre. Yes that’s a good point about the fuses. Do you mean that I cant use the rcd or is it ok to connect the neutral to the boat.

[chris w]

I am not sure of cable size I was going to ask in the shop, but the run will be about a metre. Yes that’s a good point about the fuses. Do you mean that I cant use the rcd or is it ok to connect the neutral to the boat.

 

You MUST use RCDs !! Ergo, you must connect the neutrals and earths as articulated above.

 

The cable size for your 1000W inverter should be at least 40mm² (I have assumed 1.5m each way ie: 3m total). The 300W inverter needs at least 20mm² cable for the same distance. Don't trust the "man in the shop". He/she is unlikely to know how to calculate cable sizes for inverters.

 

Don't use max current rating for cables in 12v systems (they are for mains systems). Volts drop is the primary parameter. I have calculated the above based on a maximum 0.2v volts drop.

 

Also ensure all the cables have professional crimps on them; ie: they are put on with a ratchet crimper. You can buy them pre-crimped if you don't have access to a crimper.

 

Chris

Edited February 29, 2008 by chris w

[colin loach]

You MUST use RCDs !! Ergo, you must connect the neutrals and earths as articulated above.The cable size for your 1000W inverter should be at least 40mm² (I have assumed 1.5m each way ie: 3m total). The 300W inverter needs at least 20mm² cable for the same distance. Don't trust the "man in the shop". He/she is unlikely to know how to calculate cable sizes for inverters.Don't use max current rating for cables in 12v systems (they are for mains systems). Volts drop is the primary parameter. I have calculated the above based on a maximum 0.2v volts drop.Also ensure all the cables have professional crimps on them ie: they are put on with a ratchet crimper. You can buy them pre-crimped if you don't have access to a crimper.Chris

You MUST use RCDs !! Ergo, you must connect the neutrals and earths as articulated above.The cable size for your 1000W inverter should be at least 40mm² (I have assumed 1.5m each way ie: 3m total). The 300W inverter needs at least 20mm² cable for the same distance. Don't trust the "man in the shop". He/she is unlikely to know how to calculate cable sizes for inverters.Don't use max current rating for cables in 12v systems (they are for mains systems). Volts drop is the primary parameter. I have calculated the above based on a maximum 0.2v volts drop.Also ensure all the cables have professional crimps on them; ie: they are put on with a ratchet crimper. You can buy them pre-crimped if you don't have access to a crimper.Chris

Thanks Chris I will make note of what you have said, but if I get the cable already crimped will I still get them through the bulk head and a grommet. It may be better if I buy the crimper. Colin.

[chris w]

Thanks Chris I will make note of what you have said, but if I get the cable already crimped will I still get them through the bulk head and a grommet. It may be better if I buy the crimper. Colin.

 

 

They are a useful tool to have but will set you back about £70 for one that does the big cables. Small ratchet crimpers for the more normal cables up to 6mm² are about £15.

 

Chris