Inverter question... (1 Viewer)

[mark e]

I have a 85 amp/hour battery located under the passenger seat of my ducato. Eventually fitting my 600 watt inverter tommorow before leaving for St ives on Friday.

Planning on using cables supplied with inverter but I am going to cut off the 2 battery clamps and replacing with 2 round metal rings straight to the battery.

What size inline fuse should i fit ?

 

[hilldweller]

I have a 85 amp/hour battery located under the passenger seat of my ducato. Eventually fitting my 600 watt inverter tommorow before leaving for St ives on Friday.

Planning on using cables supplied with inverter but I am going to cut off the 2 battery clamps and replacing with 2 round metal rings straight to the battery.

What size inline fuse should i fit ?

600 / 12 = 50Amps.

Start at 50A then - remember a 50A fuse blows at much more than this, they are not exactly accurate devices.

 

[scotjimland]

A fuse is to protect the cable from overload, not to protect the device , and we can assume the manufacturer supplied it with large enough cable to supply 600watt , then as Brian said .. 50A

However, If you are mounting the inverter close to the battery with short leads where there is no danger of them being damaged or chaffed and touching the chassis then personally I wouldn't bother with a fuse .. the inverter will have it's own fuse or thermal cut out to prevent it being damaged.

Jim

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[vwalan]

i use a 2500wt inverter close to the battery bank i dont use a fuse i always thought the inverter had it bult in. may be wrong but its worked for years.

 

[sinbad1]

I agree with what's been said , i would say yes to fitting a circuit breaker /fuse if it were to be used with the clips ;but as you say these will be cut off and rings either crimped or soldered on.

regards

Check with the manufacturer wether or not the unit should be earthed

 

[hilldweller]

i dont use a fuse i always thought the inverter had it bult in. may be wrong

Indeed you may be. As has been said the fuse is only to protect the wire. If there is ANY chance of the wire shorting out then fuse it.

The inverter should protect itself internally, that is not your problem.

What is without doubt, short a thick wire to earth and oh boy do you know about it. Most people will have seen a good approximation with an arc welder. In fact there is/was a cheapo kit on sale that used one or two car batteries as an arc welder. All it was was two BIG wires one with an earth clip, the other with a welding rod holder. Thinks.... was it more than that ? If the rod got stuck, as they do, it would certainly melt pretty quickly if it got full battery current.

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[vwalan]

i have used that type of welding .not very effective as battery goes flat very quick. i hope if you install it correctly it shouldnt earth out. must say be a bit difficult to fuse mine as the wire is as htick as snap on jump leads . if it catches fire best to pour more fuel on cant do much with a part burnt out van.

 

[scotjimland]

i have used that type of welding .not very effective as battery goes flat very quick. .

you don't say

 

[hilldweller]

i hope if you install it correctly it shouldnt earth out. must say be a bit difficult to fuse mine as the wire is as htick as snap on jump leads

Thinking about this a bit more, yes it shouldn't earth out but if it did, with wires that thick it will get very nasty.

Suppose the wire breaks inside the inverter, due to vibration, suppose this bypasses any internal protection, then you have one very hot box getting hotter as is the battery. Now assume this happens when you are trundling down the motorway, which is likely being caused by vibration. Oh boy, you've got burning, you've got acid fumes, you've got PROBLEMS.

So IMHO the bottom line is *always* fuse.

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[hilldweller]

battery goes flat very quick
you don't say

This should give MHers food for thought. An arc welder uses around 40...140A which at 12V is only 1600W. There are people on here regularly asking "Can I use the electric kettle on the inverter ( 3000W )". "Can my wife use her hair drier ( 1200W )" with no thought that the battery will indeed go flat very quickly.