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james

[quote:2fab09296b]But this would try to draw most of the current via the split charge relay, at best this would blow the split charging system relay (if there is a fuse fitted on several occassions I have come across systems with no fuse fitted, with no fuse its a serious fire hazard)[/quote:2fab09296b]

George

I have thought long and hard about a fuse for the split charge relay that will stand the theoretical draw from my 2500-watt inverter. This inverter has a surge capability of 5000 watts (over 400 amps at 12 volts). I certainly have a fuse for the rest of the domestic supply that does not involve the inverter.
I would have to have a fuse of over 400 amps and as the inverter has its own internal fuse, I cannot see any great need for it. No car has a fuse between the battery and the starter motor, which incidentally also involves a relay of sorts and a similar sort of amp draw. Am I wrong?

I also have a relay that is only rated for 200-amps which is about 2500-watts. I reason that this relay never switches a load and any surge is momentary, again I cannot see any problem. Surely, any relay that is rated for switching and continious use of 200 amps can stand a surge of double that for a fraction of a second? I have certainly had no problems.

James

GeorgeTelford

Hi Pete

This goes back to the earlier post about running a large invertor from the leisure battery, but at the same time running the engine to supplement the power, if this is done with a large invertor I contend that the split charge relay and wiring need to be able to handle the largest Draw that is possible, in the case of the Invertor mentioned its 250 Amps which is more than the staring ampage of most vehicles, of course the leisure battery will be the first port of call but further down the line is the Starter battery and then furthest away the Alternator, this means the share fromthe Starter and alternator need to be covered.

George

PS what always amazes me when buying new gear you will see 3 amp or 5 amp fuse specified and then when you check the Plug its still got a 13 amp fuse fitted.

Anonymous

George is still digging the same hole; he just does not know what he is talking about!!

Doug…

GeorgeTelford

Hi James

This goes to the root of the problem involving Large Invertor and then trying to power via Alternator and Starter battery too.
Its not as simple as some people think, the next major hurdle is the people who have got away with doing it wrong for years.

For momentary loads a slow blow fuse at the lower rating is called for, yep even fuses are not always the same some are rated to blow as soon as there max is exceeded (depending on temp) and others are designed to exceed the Nominal rating for a short period.

The internal fuse is usually just for reverse polarity.

The Car starter "relay"is actually a solenoid it takes a fair whack (ampage) to keep operating, because of the strong release required (it has to snap wide open very quick to avoid arcing and welding the switch) this high power overhead is not a problem due to very short time in use when starting, not so clever if you want to run stuff longer term.

Bottom Line

Use the Fuse reccomended by the Invertor manufacturer, this as nothing to do with the Split charge system fuses and the wiring rating for the split charge system.

George

GeorgeTelford

[quote:62ca6ac611="Doug60"]George is still digging the same hole; he just does not know what he is talking about!!

Doug…[/quote:62ca6ac611]

Hi Doug

Please explain where I am wrong, why does the invertor not draw current from the Starter battery and Alternator? when you are using the Invertor and have the engine running?

George

peejay · Campsite DB Admin

Hi,

Re my last post,

No blame or implication is directed against any particular person and i repeat the posts were removed because they were not deemed in keeping with the good nature and friendliness of this website.

It appears we are having a repeat episode from last night, the topic is locked 'till further notice.

pete.