# Invertor - seems expensive



## FrankiaMH (Jul 2, 2005)

Hi, 

We've been offered a invertor by our salesman and wanted to know what they are for? Are they much use in practice because I thought that normally the leisure battery would not sustain 240v for very long. However, the salesman informs us once it is connected to the engine it will run indefinately when the engine is running, is that correct?

FH


----------



## DABurleigh (May 9, 2005)

FH,

Yes, it all depends on the power consumption of the mains appliances you are running (a digital camera charger is a bit different from a hairdryer or an aircon!) together with whether the engine is running (the alternator can charge batteries at up to ~600Watts).

They are, indeed, popular. Just make sure you buy a suitable one for the applications and situations you envisage. A salesman offering a single product might not give you impartial advice here.

Dave


----------



## nukeadmin (Oct 10, 2003)

which inverter is he offering you, and how much ?


----------



## FrankiaMH (Jul 2, 2005)

*Inverter -expensive?*

The dealer is offering a built in PRO Sine 1800W for €1900 (fitted), and he claimed it would run the Dometic B 2100 air con. He recommended this model because it produces a pure sine-wave which we would need to run a laptop. However, it seems very expensive - are we being taken for a ride?


----------



## DABurleigh (May 9, 2005)

Well, I'd say a sine-wave inverter is desirable and maybe necessary to drive a mains aircon (a compressor is an inductive load), but rarely needed for a laptop, which is a low-power device anyway.

I'd be more interested in how the dealer intends arranging your alternator to deliver 85Amps continuously while doing its more normal jobs as well.

Dave


----------



## 95853 (Jul 25, 2005)

I have just got a 600w modified wave invertor from Maplins for £39-99.

It powers a 15" tv, playstation2 and a big fan for the kids whilst we are travelling. I guess we will use it mainly when travelling - but the wife is looking forward to being able to plug in her hairdryer when not hooked up!


----------



## FrankiaMH (Jul 2, 2005)

Many thanks for the answers so far. Another question:
Will a built-in invertor run continuously from the engine without draining the leisure batteries as the dealer seemed to imply?

FMH


----------



## gaspode (May 9, 2005)

Hi FrankiaMH

Sounds to me as if your salesman is more of an expert at selling than he is at inverters :lol: 

An 1800 watt inverter will draw 150+ amps from your battery when running on full load so unless you have a massive array of batteries you'll be flattening the battery in a matter of minutes. As for use with the engine runnning, that would only apply if you were running the inverter from the engine battery - unless you have a facility to switch the alternator to feed the leisure battery instead of the engine battery. The normal arrangement would be for the alternator to only charge the leisure battery after the engine battery is fully charged - and even them there would normally be a fuse in the charge line which would restrict the charging current. As with all things electrical, there are ways of overcoming these shortfalls, high output alternators, massive leisure battery banks etc. But you would have to have a very specific and compelling reason to make the expense and trouble worthwhile.

If you want to run aircon on the move, the best bet would be to retro fit engine driven aircon. Otherwise I would only advise using an inverter for low current devices such as TV, laptop, satellite, DVD etc. In which case a small (300w) modified sine wave inverter would be more than enough - and would involve no expensive fitting charges. Expect to pay £50 maximum - and a good deal less probably.


----------



## nukeadmin (Oct 10, 2003)

I have to ask, who are these dealers you are buying from FH ?


----------



## DABurleigh (May 9, 2005)

"Will a built-in invertor run continuously from the engine without draining the leisure batteries as the dealer seemed to imply?"

That was exactly the point I was making regarding 85A continuous from the alternator, as that's what you need DEDICATED to running the B2100 aircon through that inverter, which is 90% efficient max (I checked both Dometic and ProLine spec, too).

An aircon needs to run for hours at a time. This is quite different from a 1.2kW short duration device such as a hairdryer (well it is short duration so long as Alison hasn't conned me into leaving the van while she does the necessary ......)

Dave


----------



## Fatalhud (Mar 3, 2006)

Macro have a 1000watt inverter on offer £50 + vat
a saving of around £1850
for that you could afford a new lap top plus loads of spare batteries and ice creams all your round for at least a year
or as said above for about £1500 you could have aircon fitted to the motor

It would take the best salesman in the world to make me spend £1900 on a device that would pull more currant than an average home


----------

