Just starting to buy the electrics....need a bit of help (1 Viewer)

TommyG87

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Hi.
Thanks in advance for any help, new to the forum. I am a total novice with electrics...Me and my wife have stripped a horse trailer out, and in the middle of installing electrics. Ideally we want to use leisure batteries as our main source of power, when theres no hook up supply. As a back up to the leisure batteries, a pure sine inverter generator.

I have installed a 32amp 3 pin plug, which will then go to a consumer unit. From the generator, a 32amp hook up cable. However for the leisure batteries, I will be connecting a pure sine inverter, which will plug into my 32amp socket, via a 32amp to 13amp plug adaptor hook up cable. All I am wanting to power is some led light bulbs, a pretty big fridge and some small led striplites.

The leisure batteries will be installed in Parallel, and are 130ah each, 12v. To charge them, will be via a plug in battery charger, and additionally may go down the solar route later on. The inverter size, I have been told different opinions, one from an auto electrician, and one from a seller of inverters. The auto electrician said a 1600w inverter. The seller said 2500w with a peak power of 5000w. I have attached a image of the sticker off the fridge. Due to initial start up surge, id be more certain the 2500w/5000w inverter would be correct. Im also thinking I may need an additional battery or 2.

The 2nd query, when connecting batteries in parallel, does the live cables between each battery, and to the inverter need fusing, or will the built in protection of an inverter, and the consumer unit be sufficient?

Final query, from the leisure batteries, the post taking the negative cable to the negative terminal of the inverter, does an additional negative cable need taking and bolting to the metal body of the trailer for ground?

Sorry for the newbie questions, but I have had alot of mixed advice, and nowhere locally where I live, willing to undertake the work, as all the electricians seem pretty scared off, and the auto electrician wasnt 100% sure if the setup would run the fridge. Thanks
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Hi and welcome to the fun forum. I know nothing about electric apart from plugging in my hairdryer and straighteners but someone will be along soon with an opinion.
 
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Camdoon

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Hello, all this also beyond my pay grade but think about solar now as you will want to use it in the future and putting a fuse between batteries is sensible even if you consider it belt and braces.
 
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i wouldnt think any amount of batterys are going to run that fridge, i am no expert but done my own van and done a lot of reading up on it, and that one looks way over the top.
 
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138go

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No idea what a 32A three pin plug is. If it is round and blue then its 16A. If thats what you fitted then it should terminate in a Earth Leakage Trip Box. That gets the 240v into the Horse Box. Now you can sort out what you want to do. Inverters have to be matched to the load and will discharge batteries very quickly. A 2500W inverter will use about 200 Amps so two 130 Amp batteries will give you 130 Amps of useable power before you damage the batteries. You are looking at about 1/2 hour of 240V power with an output of 2500W. You will need a battery charger to charge the batteries when on hookup.

You could use 12V LED lighting which will save power and a 12v compressor fridge or a 12v and Gas fridge and use an external gas bottle when you get there. Trying to provide 240V like you get at home is really a none starter unless you have lots of battery capacity and can charge them up. You also have to consider the weight. Large leisure batteries are about 30KG each.
 
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Jun 17, 2012
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You may have to reconsider what you intend to do as your plans are somewhat ambitious.
The text in red below is from your post, please note fuses are to protect the wiring from faults/shorts so should be as close as possible to the battery.

The 2nd query, when connecting batteries in parallel, does the live cables between each battery, and to the inverter need fusing, or will the built in protection of an inverter, and the consumer unit be sufficient?
 
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Lenny HB

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No idea what a 32A three pin plug is. If it is round and blue then its 16A.
Looks the same as a 16amp just bigger, so he won't be able to plug it in anywhere.

If thats what you fitted then it should terminate in a Earth Leakage Trip Box.
They went out of fashion with the ark, I think you mean an RCD (Residual Current Device).
 
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Welcome , re the fridge , are you aware that not all are suitable for
"external" use , I run a Beko 220v external rated double door fridge freezer in my RV . I would suggest that you use a 2000w (min) psw inverter . You need more battery than you are proposing say double . I would also suggest that you want at least 500w of solar with mppt controller, if you want to operate any length of time off EHU . It is also efficacious to freeze down on ehu prior to going away . Is this going to be a "mobile Bar" ? I have seen a couple of Bedford TK Oakleys converted . Using a inverter charger would make more sense in view of possible usage eg
https://www.victronenergy.com/inverters-chargers
This would simplify the wiring set up , and give you more flexibility in what other power demands you might have . In combination with
using a smaller generator depending on what combination of solar , ehu, battery, generator you decide on .
 
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TommyG87

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That's an old fridge. R22 refrigerant is now banned, illegal even to repair such equipment :eek:
Thanks, really didnt know this, bought it 2nd hand...time to get rid lol.

Yeah the 32amp plug is basically the same as a 16amp plug, just thicker wiring. I wont be plugging into camp sites etc so thats not a worry.

Ive tried finding a suitable 12v alternative, but it needs to be a patisserie style display fridge, and just cant find any in 12v. Think I may need to buy a modern low power eco type fridge, to reduce the size of the inverter needed.

Yeah it's a mobile patisserie, and for wedding hire etc, really only need electric wise, the display fridge, lighting and a laptop (for mobile card payments).

The only thing regarding solar, why I wasnt putting as a priority now, but maybes to install for the future, is because of the UK weather, where a battery charger, and a generator for back up I can use all the time. The trailer will never be away from home for more than 1 day at a time, so can always recharge the batteries, but would be nice in the summer to just have them charging for me from solar.

So other than the fridge being illiegal and too power hungry, would you say the setup is ok, and with regards to earthing, its just done via the rcd in the consumer unit yeah?

Thanks
 
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Jun 17, 2012
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Can I suggest a gas fridge? If short trips then small bottle and cooking facilities as well. Buy a 100 watt panel to keep batteries charged so no big leads or genny required.
Simple and minimal.
 
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Can I suggest a gas fridge? If short trips then small bottle and cooking facilities as well. Buy a 100 watt panel to keep batteries charged so no big leads or genny required.
Simple and minimal.
Dont think you will find a gas powered display type fridge , also it would struggle to handle the door open time in a commercial application JMHO
@TommyG87 I have 4 T105 Trojan batteries and run the 2000w inverter to power 291 ltr Beko fridge freezer , it only drops voltage about 5 to 10 % overnight IIRC :) and that includes lights and telly etc after sunset .

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Dec 24, 2014
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I'd defo go for a quiet 240v generator. Most mobile catering units seem to use them. Much wider options for fridge etc. Running out of power at a wedding wouldn't do your reputation much good and you'd be wise to have a good supply of Diocalm available.
 
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TommyG87

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Yeah, tried finding a patisserie style fridge, 12v and gas, and couldn't find any at all. I was going to have a generator as back up, for if I do run out of power at an event, so to not leave me stranded, but did want to try and use leisure batteries as much as possible, for the noise etc, as my wife didn't want to be outside a wedding venue with a generator running. I will be making a silencer box for it, and getting a low noise genny as back up. With regards to the 100w panel to keep the batteries charged, am I right in thinking, that you can only charge them, whilst not drawing amps from them?

@tacr2man if you dont mind me asking, what watts is your fridge (im currently looking for a new fridge, as now I don't want to use that r22 one after looking into it) and what amp hour is each battery you are using? From what I can see, they are 6v is that right? Also regarding a inverter, does it constantly draw say 2000w, even when the fridge is in sleep mode or anything? or does the output of the inverter, depend on how much is being drawn? Thanks
 
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Jun 17, 2012
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Can I suggest a gas fridge? If short trips then small bottle and cooking facilities as well. Buy a 100 watt panel to keep batteries charged so no big leads or genny required.
Simple and minimal.
Apologies for not reading your 2nd post properly. Your 1st post did not suggest catering so I wrongly assumed your set up was like a trailer home, oops WRONG.
If you need to run the fridge for long, batteries are not the answer.
More practical to run a quiet 240v genny, but gas fridge is best option and use batteries for lighting. No need for inverter. (or genny)
Yes you can draw power from a battery whilst being charged whatever the charging method.
Install a solar panel and that will keep batteries charged and gas to run the fridge.
If there is 240v available switch fridge to 240v.
My MH has a 100w panel, it maintains 2 leisure batteries and a vehicle battery to be fully charged throughout the winter.
It allows me to be parked for 6 weeks on a site without hook-up in the summer.
 
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Jun 17, 2012
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Bear in mind most modern 3 way fridges default to 240v then gas, 12v is only when moving and power is sourced from the vehicle's 12v system. Generally 12v maintains temperature rather than cooling.
Anything here?
fridge.JPG
 
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Hi welcome to the forum it would be £15 pounds well spent on her just for the info you have received now
good luck with your electrics
bill

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As I'm sure you know, fridges draw power intermittently, because they run at full power for a while, then the thermostat cuts the compressor off when it's cold enough. If the fridge is already cold, and you open the door rarely, then it's probably only on for a tenth of the time. But if it's not very cold, and you're opening the door frequently, then the compressor might be running for 80 to 90% of the time. I'd say it's best to imagine it's on all the time, and treat any time that it's off as a bonus.

You need to know the power (watts) that your fridge is using, and how many hours it will be running from the batteries. For example, a 200 watt fridge running for 12 hours will use 200 x 12 = 2400 watt-hours.

Then you need to know how much energy (watt-hours) your batteries can supply. A single 100 amp-hour 12 volt battery can supply 100 x 12 = 1200 watt-hours in theory, but in practice it's best to aim to only use half of that, to avoid damage/reduced lifetime of the battery. Let's say 600 watt-hours from one battery.

So for 2400 watt-hours you will need 2400 / 600 = 4 batteries with capacity 100 amp-hours each.
If your venue is more than a few minutes away, it might be worth considering powering the fridge from the engine alternator (into an inverter) using a split charge relay that charges the batteries when the engine is running. Or a Battery-to-Battery (B2B) charger, which is more expensive but gives lots more charge.

For connections, if the batteries are all next to each other there's no need for a fuse between each battery. Fit an isolator switch and a big fuse in the positive wire right next to the batteries. It is usual to connect the negative terminals together, and to add a wire to connect to the chassis metalwork.
 
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TommyG87

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Thank you for the information. Thats a great help.
One last thing im unsure on, I have my consumer unit, which is protected with RCD & MCB's, which will be earthed to the chassis of the trailer. Coming from my outside 32a socket, will be the feed to the consumer unit. Ideally, would like to use this 32a socket, to plug the generator in directly using a 32a plug directly into the generator, and using a 32a to 13a plug adaptor directly into a domestic mains outlet.
I would also like to plug directly into this 32a socket when using my leisure battery/inverter setup. Obviously the outlet of the inverter is a standard 13a socket. So using the 13a to 32a converter lead, plugged into my 32a socket, would this be fine? I was reading about earthing issues etc. Does anyone have experience of setting up an inverter this way, so that I can use my pre installed sockets inside the trailer, or am I best off just using the inverter directly to the appliances? Reason being is the lights are 240v only, which are wired to the consumer unit. Im hoping its just a case of plugging the inverter into the 32a plug, which runs to the consumer unit.
 
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Since this is to be a business operating among the public I reckon he needs to have the work done by a professional...............but if not, good third party liability insurance (if he can get it without the work being signed off by a competent/qualified electrician).

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You say lights will be LED but later say 240v
You make the comment in red which suggests?? you will plug the inverter into 32a socket?? The inverter should be connected to the batteries.
I would also like to plug directly into this 32a socket when using my leisure battery/inverter setup. Obviously the outlet of the inverter is a standard 13a socket. So using the 13a to 32a converter lead, plugged into my 32a socket,

I have made a very quick sketch of what I think you need, or I may be wrong.
Bring 240v to consumer unit with a couple of spurs for 13a sockets and mains lighting.
When on batteries only, plug fridge into inverter and use 12v lighting.

The sketch is not intended for actual wiring but merely to find out what you actually are trying to achieve.

sketch.JPG




 
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Coming from my outside 32a socket, will be the feed to the consumer unit. Ideally, would like to use this 32a socket, to plug the generator in directly using a 32a plug directly into the generator, and using a 32a to 13a plug adaptor directly into a domestic mains outlet.
I would also like to plug directly into this 32a socket when using my leisure battery/inverter setup. Obviously the outlet of the inverter is a standard 13a socket. So using the 13a to 32a converter lead, plugged into my 32a socket, would this be fine?
Plugging the generator, mains hookup or inverter as necessary into the 32A socket will appear to work fine. However there is a fundamental problem if you have a mains charger permanently connected to the batteries.

When plugged into the mains hookup or generator, the mains charger will charge the batteries exactly as you want. However when the inverter is plugged in, the inverter (running from the batteries) will be powering the mains charger that is trying to charge the batteries. This is undesireable.

You can avoid this by remembering to manually switch off or unplug the mains charger when the inverter is providing power. Alternatively, it is relatively simple to set up a relay so that the mains charger is automatically switched on if the generator or mains hookup is connected, and otherwise remains off.
 
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TommyG87

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Many thanks for the help everyone, I have spoken to tacr2man via PM and has gave some great advice also.
Thanks autorouter, yeah I am covering this with a Isolator switch, because me and my wife will be the only ones using the trailer I will drum it in to her that this stays off at all times when the battery/inverter set up is being used.

I am certainly doing the work myself and although being new to the world of camper van electrics, i'm no fool! I already have contacted a professional who is going to check over my work and pat test any appliances prior to any power supply being plugged in. Only wanting to do the work myself, to learn and self satisfaction of doing this project, but certainly not skimping on safety. Yup, public liability is a must, I run my own car mechanic business. If any one ever needs any help or advice on the mechanic side of things, or running issues, feel free to PM me, I am pretty clued up on the engines used in a a lot of motor homes. (citroen, peugeot hdi engines etc)

Once again, many thanks for your help everyone.
 
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Cheshirecat57

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Many thanks for the help everyone, I have spoken to tacr2man via PM and has gave some great advice also.
Thanks autorouter, yeah I am covering this with a Isolator switch, because me and my wife will be the only ones using the trailer I will drum it in to her that this stays off at all times when the battery/inverter set up is being used.

I am certainly doing the work myself and although being new to the world of camper van electrics, i'm no fool! I already have contacted a professional who is going to check over my work and pat test any appliances prior to any power supply being plugged in. Only wanting to do the work myself, to learn and self satisfaction of doing this project, but certainly not skimping on safety. Yup, public liability is a must, I run my own car mechanic business. If any one ever needs any help or advice on the mechanic side of things, or running issues, feel free to PM me, I am pretty clued up on the engines used in a a lot of motor homes. (citroen, peugeot hdi engines etc)

Once again, many thanks for your help everyone.
Bye Bye.
 
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