Inverter installation

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Kemp

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About to get new inverter: cont. power 2500W; peak load 3000W (3s) ; 4000W (0,2s). According to the manual minimal DC fuse (slow blow) is 300A and minimal cable size 95 mm².

1) Should I get 350A or 400A fuse?
2) Would it be okey to combine two 50mm² cables instead of a single 95mm² cable?
 
Either fuse should do. It's OK to use 2 x 50mm2 cables. How big is your battery bank, and how far away from the inverter?
 
It is interesting how often a manufacturer will quote a cable size without specifying a maximum distance for that cable size and offering suggestions for different length runs.
 
Thanks. 500A fuse would be overkill? Have a spare one. Battery bank... well physically 8x 160Ah Winston cells should end up as 320Ah, but "somehow" they are marketed and sold as 360Ah.

Regarding the cable length. Now there is 1-1.5m of 50mm² cable from the battery to Mastershunt (500A). It will be additional min. 1-1.5m or max. 2.5-3m from Mastershunt to inverter.
 
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Kemp said:
Thanks. 500A fuse would be overkill? Have a spare one. Battery bank... well physically 8x 160A Winston cells should end up as 320A, but "somehow" they are marketed and sold as 360A.

Regarding the cable length. Now there is 1-1.5m of 50mm² cable from the battery to Mastershunt (500A). It will be additional min. 1-1.5m or max. 2.5-3m from Mastershunt to inverter.
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500A fuse would be OK, mounted next to the battery bank. I believe your Mastershunt contains an internal fuse rated at 300A continuously, so you may need to check that this is OK for the peak current (inverter plus anything else running off the batteries).

Your 8 160Ah Winston cells will give 320Ah at 12v, despite whatever marketing claims there are!

I'd think, with the cable distances you've quoted, you're right at the limit for 95mm2 cable, so perhaps best to double-check the voltage at the inverter when it's running at high output. Remember that you'll need equally meaty cable from the batteries to the Mastershunt.
 
pvb said:
I'd think, with the cable distances you've quoted, you're right at the limit for 95mm2 cable, so perhaps best to double-check the voltage at the inverter when it's running at high output. Remember that you'll need equally meaty cable from the batteries to the Mastershunt.
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totally agree. If it were at all possible I’d encourage the OP to get the inverter closer.
 
Mastershunt internal fuse is 500A (slow blow). I had an idea to replace it with 400A and use 350A for inverter.

I will try to figure out the shortest possible length with inverter on hands, but it is complicated with battery and Mastershunt installed in the engine compartment.

Welcome to the sweet lies of Mastervolt. Not sure this is even legal to package 8x160Ah rated cells and sell as 360Ah (at 12V).
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95mm cable is to combat voltage drop, the 300a fuse is to protect the cable. The cable is rated at 500a, so the fuse gives good protection.

50mm cable is rated at 345a, so a pair of cables would be rated at 690a and either of the 350a, 400a or 500a fuses would protect the cables. However, if one of the cables became detached or broken you are left with a single 345a cable carrying the full inverter load, but, more importantly, each cable would singularly be protected by the fuse. A 500a fuse is clearly overrated for 345a cable, as is a 400a fuse, so, fit the 350a fuse.

IMO, it's bad practice to run parallel power cables.

Regarding the cable length. Now there is 1-1.5m of 50mm² cable from the battery to Mastershunt (500A). It will be additional min. 1-1.5m or max. 2.5-3m from Mastershunt to inverter.
Click to expand...

Lets call it 1.5m to the shunt and 2.5 to the inverter, that's a single 1.5m cable and a pair of 2.5m cables, 7.5 in total. 12v Planet price for that is £116.40 (8m of tinned cable). Using 95mm cable you'd need 4m, which at 12v Planet prices would cost £103.16. Costs less to do the job properly and you have a 1.5m length of 50mm cable left over.
 
Kemp said:
Thanks for all info. The only problem... my crimping tools is max. 70mm² ;)
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Can you get someone to make the crimps for you ?

If not, just make sure you don't go over 350a with the fuse. Your inverter will draw about 250a if it's loaded to 2500w, 300a at 3000w, so you don't really need to exceed 300a for the fuse and that would protect a single 50mm cable.
 
I have a 2500W inverter/charger which required 95mm2 cable to avoid voltage drop.

I too only had a max 75mm2 crimper, so i took the cables to a local electrical workshop, (the type of place that does alternators and stuff), and they crimped my terminals on.
 
As a matter of interest what do you plan to run from it? Anything that takes 2500 watts is pulling over 200 watts from a 12 volt battery bank, and you will need a big battery bank to support that.
 
Norman_E said:
As a matter of interest what do you plan to run from it? Anything that takes 2500 watts is pulling over 200 watts from a 12 volt battery bank, and you will need a big battery bank to support that.
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Elessar said:
You have an Amps/watts typo.
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A 2500w 240v load on the inverter will draw about 250a from the batteries, but i get your point (y)
 
it is probably a good idea to buy a high powered inverter. Not so very expensive for large power rating. What is not a good idea is to use that power to any large extent. As mentioned the current drain at 12volts is just so huge at full power. if you really want that sort of power from an inverter you need to go to 24v or even 48volt battery sytem. Just to get more manageable currents. ol'will
 
Norman_E said:
As a matter of interest what do you plan to run from it? Anything that takes 2500 watts is pulling over 200 watts from a 12 volt battery bank, and you will need a big battery bank to support that.
Click to expand...

I specced my 2500W inverter to be able to use a Vacuum Cleaner I had at the time. Given the size of the boat, I never needed to run it for more than 10 or 15 minutes, max.. At 200A, I would use no more than about 50Ah out of a 300/400Ah bank. Always run the engine if I'm using it to draw high power, so at least something is going back into the batteries. Also use it to run less powerful stuff like a coffee maker, lawn mower, strimmer, etc..
 
Richard10002 said:
I specced my 2500W inverter to be able to use a Vacuum Cleaner I had at the time. Given the size of the boat, I Also use it to run less powerful stuff like a coffee maker, lawn mower, strimmer, etc..
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Lawn mower? strimmer? You have lawns on your boat ?
 
Richard10002 said:
I specced my 2500W inverter to be able to use a Vacuum Cleaner I had at the time. Given the size of the boat, I never needed to run it for more than 10 or 15 minutes, max.. At 200A, I would use no more than about 50Ah out of a 300/400Ah bank. Always run the engine if I'm using it to draw high power, so at least something is going back into the batteries. Also use it to run less powerful stuff like a coffee maker, lawn mower, strimmer, etc..
Click to expand...
My inverter is specced to run an electric kettle OR the microwave. So I can have hot stuff at anchor or at sea without firing up the genny.
In fact my inverter only feeds the microwave and one socket in the galley - nothing else.
My Dyson does all my vacuum cleaning without caning my batteries.
 
VicS said:
Lawn mower? strimmer? You have lawns on your boat ?
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:) :) :)

Narrowboat on a grassy/muddy offline mooring. One of the club rules is that you keep your mooring tidy - I didn't mention the brush cutter, hedge trimmers, and pruning chainsaw type thing :)

If I ever venture on a canal going trip, the strimmer can also come in handy if the eventual mooring spot is a bit overgrown.

I now have had a rechargeable Dyson V6 for a few years, so only need to connect the wired version occasionally.
 
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