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I want to supply a 3Kw inverter it will allow 6Kw for up to 5 minutes but with the supply from 3 x 110AH batteries at 3Kw the maximum time will be 1.5 hours and likely less than that. Looking at Table 4F1A it states 95mm² but that does seem a very thick cable and considering the limited time for which the maximum demand can be drawn it seems a little OTT.
I was considering between 35mm² and 70mm² welding cable. Looking at welding cable 35mm² is ratted 225A at 100% and 50mm² is ratted 285A at 100% which seem far more realistic figures. The temperature is higher than table 4F1A at 85ºC. BS638 HOFR cable being oil resistant does seem the right cable to use within the engine compartment. And although 3Kw equates to 250A I would consider it very unlikely that maximum would be drawn for anything more than a few minutes.
If in an emergency an electric kettle was used it boils in 6 minutes. And with a range stove it would only be an emergency where an electric kettle is used.
So to make install easy I was considering using 35mm² but having never run such a large inverter on such a low voltage before I am uncertain as to how it will perform. Has anyone tried using an inverter of this size?
Second question is the switching. There is a small switch on the unit I would guess no more than 20A so I am sure not connected to the 10mm DC in studs. And I was wondering if it needs it’s own isolator. There is a main isolator already on the batteries but the details say it draws 1.25A when idle and that is quite a draw. I have considered getting either an isolator or a relay the latter would allow remote operation but would be a further draw on the battery. I seem to remember some small round relays used on fork lifts which would likely fit the bill but no idea where to get them from. Think last ones I had came from Durite (Gordon Equipment). Again has anyone experience with these?
The inverter will be passed over at Christmas and until then I don’t have a battery big enough to power it and even if I did I only have an AC ammeter able to measure that amount of current. So I want to find out what I need to go with it before passing over as everything will be closed at Christmas. I already have a set of 120mm² crimp pliers ready to put on the lugs and some 35mm² cable but no isolator or lugs yet.
Any help in getting all set up ready will be appreciated. I would normally stick this on a canal forum but the recipient might read it so don’t want to do that.
I was considering between 35mm² and 70mm² welding cable. Looking at welding cable 35mm² is ratted 225A at 100% and 50mm² is ratted 285A at 100% which seem far more realistic figures. The temperature is higher than table 4F1A at 85ºC. BS638 HOFR cable being oil resistant does seem the right cable to use within the engine compartment. And although 3Kw equates to 250A I would consider it very unlikely that maximum would be drawn for anything more than a few minutes.
If in an emergency an electric kettle was used it boils in 6 minutes. And with a range stove it would only be an emergency where an electric kettle is used.
So to make install easy I was considering using 35mm² but having never run such a large inverter on such a low voltage before I am uncertain as to how it will perform. Has anyone tried using an inverter of this size?
Second question is the switching. There is a small switch on the unit I would guess no more than 20A so I am sure not connected to the 10mm DC in studs. And I was wondering if it needs it’s own isolator. There is a main isolator already on the batteries but the details say it draws 1.25A when idle and that is quite a draw. I have considered getting either an isolator or a relay the latter would allow remote operation but would be a further draw on the battery. I seem to remember some small round relays used on fork lifts which would likely fit the bill but no idea where to get them from. Think last ones I had came from Durite (Gordon Equipment). Again has anyone experience with these?
The inverter will be passed over at Christmas and until then I don’t have a battery big enough to power it and even if I did I only have an AC ammeter able to measure that amount of current. So I want to find out what I need to go with it before passing over as everything will be closed at Christmas. I already have a set of 120mm² crimp pliers ready to put on the lugs and some 35mm² cable but no isolator or lugs yet.
Any help in getting all set up ready will be appreciated. I would normally stick this on a canal forum but the recipient might read it so don’t want to do that.
