Inverter current draw

[EnglishRob]

Hi all,

Just had 3000W inverter fitted to my motorhome, twin 75 amp/hr Exide leisure batteries, cable size 00 gauge with 300 amp fuse. When the fuse was connected it sparked on first contact, then settled down. Inverter worked ok (when tested for 20 seconds) powering our microwave but even when the inverter is switched off it was still drawing 3.4 amps! Is this to be expected?

Thanks in advance

Rob

 

[BillyKontiki]

Perhaps I need to search down the back of the sofa for any loose change to enable me to purchase a Lithium battery by the sounds of it

Hope you had some rich dudes sitting on your sofa.

 

[John H.]

Capacitors needs to be energised before use.

That is the trick. Keep the DC power (and hence the capacitors) on all of the time. The inverter should have an on/off switch (preferably with a remote switch, then the inverter can be out of sight). Ours uses next to no power when switched off.

 

[Raul]

That is the trick. Keep the DC power (and hence the capacitors) on all of the time. The inverter should have an on/off switch (preferably with a remote switch, then the inverter can be out of sight). Ours uses next to no power when switched off.

That’s normal operation not a trick. The reason I mentioned it, is because it’s been mentioned to isolate the dc from battery when not in use. That’s not good, each time you turn on DC supply, you give a jolt of inrush current to the caps. You could add a resistor to energise then remove it. That would be a right faf about. If it has consumption with AC off, then DC is leaking, not properly isolated. Usually with Chinese inverters they skimp on components, and only minimum is used. Same goes for their lousy transformers, noisy and power hungry.

 

[pappajohn]

Raul,

I hope to confirm in the next few days whether the inverter is up to the job without draining the batteries whilst on standby - not too confident though

At present it's drawing 3.4ah on standby and you have 2 x 75ah batteries.
3.4 x 24hrs..... 80amps or in other words just over the 50% recommended maximum discharge rate.

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[Raul]

At present it's drawing 3.4ah on standby and you have 2 x 75ah batteries.
3.4 x 24hrs..... 80amps or in other words just over the 50% recommended maximum discharge rate.

That is only true, assuming there is no charge coming in, during inverter operation.

 

[pappajohn]

That is only true, assuming there is no charge coming in, during inverter operation.

That's true.... But assuming no hookup or solar it will consume 80amp in a 24hr period if not isolated from the battery. .

 

[Richard n Ann]

The first thing I'd do is fit a NASA BM2 Battery monitor. Can't imagine life without one now

 

[EnglishRob]

That's true.... But assuming no hookup or solar it will consume 80amp in a 24hr period if not isolated from the battery. .

I do have 100w solar which I estimate puts back 4-5 amps/hr.
The bottom line I think is to upgrade my batteries to gel, rated at 170 amp/h (according to an online calculator I came across), in order to power our microwave for 30 mins max at any one time and to not deplete the batteries below 50%.

Hope you had some rich dudes sitting on your sofa.

Only the missus