Inverter Position?

[syd]

Hi all,
I've just aquired a fan cooled inverter for my Bayliner. The instructions warn me not to extend the main wires to the inverter, keep it away from heat, moisture and fumes. The only place the wires will reach the batteries is in the engine bay, its dry and has a blower but there are still some fumes and some heat. Will the engine bay be suitable? Any help please?
cheers Syd

 

[BarryH]

If its anything like the inverter Ive got, you can cook breakfast on the damn thing when its running. My one is installed in the engine room? it don,t seem to affect it at all. the instructions that came with my one said the same thing about not extending the wires, i think this has to do with voltage drop. but i had too as the existing wires only allowed me to fit it right next to the battery and that was too low in the boat for my liking.

 

[Guest]

Think it's okay. the moisture and heat to keep away from are wetter and hotter than just a location in the engine bay. located it high up out of the way, praps bulkhead forward of the engine. it mustn't have rain on it, or have high heat attit. It's a transformer.

 

[byron]

Where-ever you site it, it would be an idea to have an 'off' switch between it and the battery. Remember Inverters are drawing some power all the time they are on, even if you aren't actually using them. Unless it's one of those super-duper ones that only switch on as you apply a load.

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[ccscott49]

I have just moved mione out of the engine room as it got too hot and triggered the thermal cut out! You can extend the cables, if you use bigger cables (cross section) Its the volt drop they are worried about. I moved mine onto the other side of the engine room bulkhead, its fine now, but they do get pretty hot on their own, they are doing a lot of work, and the low voltage current is very high!

 

[Geoffs]

I would say if at all poss. keep out of engine bay. I bought a 300watt inverter at SIBS, not sure why, it was a good price and thought it might come in useful! I've run it up to full load (3 X 100 watt bulbs) off car battery, with engine running, so 14 volts. It runs as cool as a cucumber, modern units are very efficient. Mine draws about 25 amps at full load, on 14V.

Colin is right, it's voltage drop that would be a problem with longer cables. How big is your unit? 300 watt, like mine, would be OK with 2 metre cable run and 10mm2 cable. As a guide a 10mm2 cable drops about 2mV per amp per metre. Rmember current goes to and from device, so a 2metre run is 4 metres of cable.

Byron is right about a switch. Even if the unit has a switch on it like mine, fit a switch, as often there is a wapping great capacitor on the input. Even when switched off, I get a hell of a flash when connecting to battery, as capacitor charges.

 

[syd]

Sorry, forgot to include the size, its a 1500 watt.
Syd

 

[Guest]

Should have a fuse as well!

 

[tripleace]

I have 500 watt unit, mounted in locker above engine bay. A good electrician extended the cables but did this by replacing and very much increasing the size. distance is not your enemy, it loss.

 

[Guest]

ooof! so that's drawing maybe 150 amps. you don't need extension cables, you need busbars.

 

[byron]

Whoa Syd, that's a whopper (as the girls never say to me). I guess it's one of those special super ones that cut in automatically when you put a load on. You will need very hefty cables coupled to tons of battery power for it. Surely it came supplied with a kit and instructions.

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[ccscott49]

Mines a 1800 watt one, Byron, but 24 volt, so the current is half that of Syds' He will need gigantic cables, it will be drawing 135 amps at max load, bloody hell thats like a starter motor on a small diesel! But of course the cables on a starter circuit are much smaller due to the fact they are not under that load for long, I would agree, he will need some fairly hefty batteries aswell. You say you aquired it, Syd, I bet it was cheap aswell! I would be thinking, do I really need this?

 

[Geoffs]

Wow that is a big ‘un. That will draw about 0.5amp under no load conditions, and about 10 amps per 100watt of load, as a rough guide for cable design. I think for such a whopper you will need to mount as close to battery as possible, probably need at least 150AH battery, otherwise the battery internal resistance may become a factor.

Don’t know what you want to run off it, but unless you’ve got lots of batteries, and a big Bayliner to put ‘em in, may need to run main engine(s) if going to be used at full load for any time. A 150AH battery won’t supply 150 amps for an hour, ½ hour maybe if lucky.

Cables will need to be at least 70mm2, that’s nearly starter cables, you say it comes with cables, if they are 70mm2 they’ll be about 12mm overall diameter. Electric pipe! You may need someone with a hydraulic crimper to make off terminal ends.

 

[syd]

Yep its a monster allright, I was advised this size because of the microwave on board.
it only came with an invoice and a bit of paper telling me what not to do i.e don't get it wet, or hot etc. The cables are 22mm thick! Rated at 600volts, I have three batteries on the boat and the intention is to use the inverter whilst under way for the kettle, microwave and toaster (not all at once). Do you all think 1500W is overkill. If it is its all her in doors blooody fault.
Cheers
Syd

 

[Geoffs]

Hmmm, cables sound OK, probably about 95mm2, my cable chart doesn't go above that! I think you will need to follow installation advice you have and use their cables. As I said as near to battery as poss., if heat and ventillation OK for battery should be OK for inverter. You'll have a right wrestling match with those cables.

Beware most electric kettles are 3KW (3000 watts). If you hunt around electrical stores you should find 1.5KW, but it will boil slower. Toasters not sure about, check rating on rating plate. Microwave, you'll need one of the smaller ones, 650W, as supply rating is a lot more. I think 650w is about 1KW. So for what you want 1500w is not an over kill, her in doors is off the hook! You just need a bloomin great 12v supply to run it.

Inverters and generators fascinate me. When I took the kids to the fun fair you'd hear the cry 'Where's Dad?'. 'Oh he's off looking at the generators!'

 

[BarryH]

Re: What about the alternater...

...I would seriously look at the output of the existing one. i would only spark this Behemoth up if the engines running. Knowing the yanks, if its a mercruieser its probably only got a 75-95 amp one fitted. That thing is gonna flatten those batteries in no time

 

[syd]

Do you think I ought to add another battery to the three I already have? Or will I get away with it.
Cheers
Syd

 

[syd]

Do you think I ought to add a fourth battery or will I get away with the three?
Cheers
Syd

 

[Geoffs]

Re: What about the alternater...

Good point. But if there's a couple of hundred amp hrs of battery and 75-95 amps from alternator might just get away with 1/4 or 1/2 hr kettle boiling or toast making, with engine run post use for battery top up. Need engine running at more than tickover, I suspect. It's on the ragged edge, 1500w is asking quite a lot of 12V.

 

[Geoffs]

What size, amp hour are the batteries? Are there 2 for domestic power and one on a separate circuit for engine starting? Whilst you don't want to complete flatten any battery, you are safer if you can at least start engine(s).