Volt amps? what's next?

[The Ents]

So there we were, rubbing down the paint with a 750 Watt drill. Power was supplied via a Kipor 2000 generator, ( which is, of course,) rated at 1600 KVA. (2000 by name, 1600 by performance? Hmmm.) The generator was plugged into the boat's charger/inverter a Stirling unit. after only three minutes the overload on the generator cut in and the (gas) kettle went on.

 

The generator was then run powering only the drill and all was well all day.

 

This suggests to my fuddled brain that the Stirling unit was taking over 850 Watts, at 12 volts allowing for losses, say, 85 amps just to keep my batteries, ( 4 off 110 AH,) going powering only the fridge.

 

Look it has been a long time since I studied such things, is watts to volt amps factor an issue here, or do I need to look at the demands of my battery bank? The batteries did set the CO alarm off in the heat two weeks ago whilst on shore power.

 

Any advice gladly received,

 

Mike.

 

 

[bigste]

When the drill is running it draws 560 watts but that is with not load. Soon as you put a load on it the draw will be much more and if you put 25 stone behind it who knows what it will draw.

How do I know you are 25 stone? Pure guess. lol

Edited August 12, 2013 by bigste

[Iain_S]

I think the drill rating will be on full load, although it could exceed that if overloaded, I suppose. What state of charge were the batteries? (and do you know what current was going into them?)

 

There is also the power factor to take into account. Both drill and charger/invertor are likely to be inductive loads, so this will be less than 1, possibly a lot less.

 

Iain

(who once fried a 4kVA genny with a 3kW welder )

[nb Innisfree]

Genny is 2kva max output, 1.6kva rated means continuous output. Most, if not all, gennies are quoted similarly, equivalent 2kva Honda is the same, 1.6kva rated.

[The Ents]

When the drill is running it draws 560 watts but that is with not load. Soon as you put a load on it the draw will be much more and if you put 25 stone behind it who knows what it will draw.

How do I know you are 25 stone? Pure guess. lol

Hi bigste,

 

OK, so I might have put some of my not inconsiderable weight on it. But it worked for several hours after the invereter was disconnected, so I guess I must look here first?

Mike.

I think the drill rating will be on full load, although it could exceed that if overloaded, I suppose. What state of charge were the batteries? (and do you know what current was going into them?)

 

There is also the power factor to take into account. Both drill and charger/invertor are likely to be inductive loads, so this will be less than 1, possibly a lot less.

 

Iain

(who once fried a 4kVA genny with a 3kW welder )

Hi Ian,

The batteries were down to 12.4 Volts, low as I like to see them perhaps, I do know that the charger/inverter was giving them 14.6 Volts. I have no ammeter on the charge circuit. Will the charger be an inductive load? or will this in turn be influenced by the drill load on top?

 

Mike.

Genny is 2kva max output, 1.6kva rated means continuous output. Most, if not all, gennies are quoted similarly, equivalent 2kva Honda is the same, 1.6kva rated.

Hi,

I should have guessed the rating system. Is there a standard time for overload, say one minute? Or is it in seconds?

Mike.

[nb Innisfree]

Hi,

I should have guessed the rating system. Is there a standard time for overload, say one minute? Or is it in seconds?

Mike.

From memory 30 mins.

 

Though I wouldn't go that long, 15min for me.

Edited August 13, 2013 by nb Innisfree

[bottle]

Generator runs drill.

 

Generator runs combi

 

Generator will not run drill and combi

 

Batteries set off CO alarm

 

Suspect battery problem and or charger (combi)

 

Any thoughts peolple.

[smileypete]

Generator runs drill.

 

Generator runs combi

 

Generator will not run drill and combi

 

Batteries set off CO alarm

 

Suspect battery problem and or charger (combi)

 

Any thoughts peolple.

 

 

Batt chargers can have a much higher power factor and genny requirement than their output power suggests, particularly if the genny is an inverter model.

 

This is because the current waveform can have much higher peaks than a normal load, this can overload the inverter part of the genny, or at least cause it to trip on overload.

 

cheers, Pete.

~smpt~

[The Ents]

 

 

Batt chargers can have a much higher power factor and genny requirement than their output power suggests, particularly if the genny is an inverter model.

 

This is because the current waveform can have much higher peaks than a normal load, this can overload the inverter part of the genny, or at least cause it to trip on overload.

 

cheers, Pete.

~smpt~

Thanks for that Smileypete,

 

How could I check that without an oscillascope? I have borrowed a clammeter to measure the dc current to my batteries when on charge and will report shortly on this.

 

Mike.

[smileypete]

Thanks for that Smileypete,

 

How could I check that without an oscillascope? I have borrowed a clammeter to measure the dc current to my batteries when on charge and will report shortly on this.

 

Mike.

 

Bit of a suck-it-and-see, sometimes the charger will have a VA rating on the nameplate. The more expensive chargers with 'Active PFC' (power factor correction) will be kinder to inverter gennys, some have an AC limiting function as well that can work well to limit the load on the genny.

 

The small el-cheapo inverter gennys seem to be least capable, best downrate quite generously if using with a cheaper charger.

 

cheers, Pete.

~smpt~