12v electric for wifi

[Guest]

For small electrical equipment like a wifi box which uses a step down transformer, would I be able to somehow wire into the 12v system on the boat?

 

thanks

graham

[Robbo]

23 minutes ago, Charles_Graham said:

For small electrical equipment like a wifi box which uses a step down transformer, would I be able to somehow wire into the 12v system on the boat?

 

thanks

graham

Yes, but use a dc 2 dc transformer to get a stable voltage as your boat voltage can go up to 14+v which may be too high for some sensitive equipment.

Edited December 30, 2018 by Robbo

[Alan de Enfield]

20 minutes ago, Charles_Graham said:

For small electrical equipment like a wifi box which uses a step down transformer, would I be able to somehow wire into the 12v system on the boat?

 

thanks

graham

The thing to be aware of is that if the 'appliance' requires a stabilised 12v supply then you are likely to damage it running it from the batteries.

Your battery voltage will probably vary between 12v and 14.4 volts (depending if the engine is running / battery charger is on).

 

I have a 12v TV but cannot run it directly from the 12v batteries - I have to use a 'brick' in the supply line ( a stabilised 12v supply, that irrespective of the voltage going in will only put 12v out)

 

With right 'adapters' you can do pretty much anything

 

I run my 19v laptop from the 12v cigarette lighter socket, and I charge my 7.2 volt GPS and VHF radio from a 5v USB socket.

[Dr Bob]

Agreed, straightforward to find a solution but why not just use 240V? If you have a half decent inverter then it wont take that much power and you can use 240V on all the things you normally power. Our 240V is on 24/7 and powers our small and large electrical equipment - lights and pumps are on 12V of course plus the other boaty related stuff. I wouldnt have a boat again that had most stuff on 12V.

[Alan de Enfield]

12 minutes ago, Dr Bob said:

Agreed, straightforward to find a solution but why not just use 240V?

It does seem to be a pointless waste of energy to generate 12v DC, invert it to 230v AC (with all of the efficiency losses + Inverter powering losses), then reduce it back to 12v DC (with the attendant losses) when you can just take 12v DC and power a 12v DC appliance that you already have.

[ditchcrawler]

29 minutes ago, Alan de Enfield said:

It does seem to be a pointless waste of energy to generate 12v DC, invert it to 230v AC (with all of the efficiency losses + Inverter powering losses), then reduce it back to 12v DC (with the attendant losses) when you can just take 12v DC and power a 12v DC appliance that you already have.

I have often wondered what the differences in the efficiencies actually equal. The DC/DC converter is not 100% efficient. at the end of the day is it 1Ah per day or 10Ah per day My inverter probably uses 10Ah per day but then it also runs my fridge 12/7 or the bread maker every third day and the coffee maker every evening, so how much more power is being used by my MiFi plugged into the USB socket 24/7 ?

 

Edited December 30, 2018 by ditchcrawler

[Richard10002]

If you are running the inverter anyway, running a mifi via a USB wont use anything significant. If you are running the inverter just to power the Mifi, its quiescent current of 10Ah per day is wasted.

 

In fact, given that USB is 5v, you can plug a USB into the 12V system, and run the Mifi from the USB... no need for 240v.

[Dr Bob]

9 hours ago, ditchcrawler said:

I have often wondered what the differences in the efficiencies actually equal. The DC/DC converter is not 100% efficient. at the end of the day is it 1Ah per day or 10Ah per day My inverter probably uses 10Ah per day but then it also runs my fridge 12/7 or the bread maker every third day and the coffee maker every evening, so how much more power is being used by my MiFi plugged into the USB socket 24/7 ?

 

If you have a 240V fridge it is obvious to use 240v for the MiFi. A 12v fridge will be far less efficient and so, so, much more expensive. Choice of 12v TV's is much more limited. Washing machines, coffee makers etc are 240V. A 12V only boat seems too much like camping. We lived on one for 3 years in the Med with 240V only when plugged in in a marina so do know the difference.

[Phil Ambrose]

32 minutes ago, Dr Bob said:

If you have a 240V fridge it is obvious to use 240v for the MiFi. A 12v fridge will be far less efficient and so, so, much more expensive. Choice of 12v TV's is much more limited. Washing machines, coffee makers etc are 240V. A 12V only boat seems too much like camping. We lived on one for 3 years in the Med with 240V only when plugged in in a marina so do know the difference.

Strange, 20 years living aboard with both a 110 ltr larder fridge and a 80 ltr freezer both 12v and found them both to be efficient. Yes more expensive but hey so are inverters

I too cannot see the point in taking perfectly good 12v electricity and turning it into 240v

Phil

[Alan de Enfield]

17 minutes ago, Phil Ambrose said:

I too cannot see the point in taking perfectly good 12v electricity and turning it into 240v

And then turning it back into 12v, or even 5v (for USB powered appliances)

[Dr Bob]

6 minutes ago, Alan de Enfield said:

And then turning it back into 12v, or even 5v (for USB powered appliances)

Go back to posts 2&3. If you have a 240v fridge and need some form of stabilization for 14.2V to 12V then it's far less faffing to use 240V. The discussion then comes back to whether the OP wants the comforts of 240V devices rather than voltage changing efficiencies. I'm glad we are all different. This forum would be boring if we were all the same. 

 

Me, I like my 240V devices. 

A question for you 12V only peeps. How do you manage with soldering irons, dremmels, charging cordless drill batteries, charging cordless vacuum cleaner batteries, charging.......?

[Momac]

1 hour ago, Dr Bob said:

 A 12V only boat seems too much like camping. 

Interesting thought . But regardless of whether 12vDC or inverted to 240VAC is used  the electrical energy available when away from shore power is limited by the capacity of the  battery bank. And that energy is diminished by the inverter.

 

1 minute ago, Dr Bob said:

 

A question for you 12V only peeps. How do you manage with soldering irons, dremmels, charging cordless drill batteries, charging cordless vacuum cleaner batteries, charging.......?

 I charge them up when on shore power  or could (but don't need to) use a portable generator. But i don't live on the boat and  keep the boat in a marina with shore power so it has never been a problem . For living aboard I see your point especially if you have space for a 240V fridge  which will cost less than half a 12V/dual voltage fridge .

 

 

[colinnorth]

Having taken hundreds of routers/wifi boxes apart as part of a re-cycling effort I can say that all of them that I have looked at have a DC stabilisation circuit immediately after their DC input socket.

I have used all of my 12V appliances immediately off the boat 12v which for me normally sits at about 13.4v with the solar panels running, 14.4V whilst cruising and 12.6V during the evening. I have not experienced any overheating problems.

[dmr]

1 hour ago, Dr Bob said:

Go back to posts 2&3. If you have a 240v fridge and need some form of stabilization for 14.2V to 12V then it's far less faffing to use 240V. The discussion then comes back to whether the OP wants the comforts of 240V devices rather than voltage changing efficiencies. I'm glad we are all different. This forum would be boring if we were all the same. 

 

Me, I like my 240V devices. 

A question for you 12V only peeps. How do you manage with soldering irons, dremmels, charging cordless drill batteries, charging cordless vacuum cleaner batteries, charging.......?

 

We have an inverter that we turn on just when required for a few mains devices, the soldering iron, printer, and the little food processor are the most common. However we also have the wonderful Travel Power so things like drill and Dyson battery chargers are left plugged in all the time and automatically get a charge when the engine runs.

 

We are getting more and more stuff that charges from USB so I have fitted a few 12 volt USB sockets and this was maybe a bad idea as a lot of stuff is now on permanent charge putting a constant small drain on the batteries. Maybe I should get some mains powered USB charging for some of these things.

 

Got a new battery charger last year and leave it turned on all the time to help the alternators (via TravelPower), trouble is whenever I turn the inverter on I forget to turn the charger off and so send the leccy round in a very inefficient circle.

 

..................Dave

[Tony Brooks]

1 hour ago, Dr Bob said:

Go back to posts 2&3. If you have a 240v fridge and need some form of stabilization for 14.2V to 12V then it's far less faffing to use 240V. The discussion then comes back to whether the OP wants the comforts of 240V devices rather than voltage changing efficiencies. I'm glad we are all different. This forum would be boring if we were all the same. 

 

Me, I like my 240V devices. 

A question for you 12V only peeps. How do you manage with soldering irons, dremmels, charging cordless drill batteries, charging cordless vacuum cleaner batteries, charging.......?

 

Soldering irons as was normal - put it on the gas stove. I was sensible enough to rescue a number of different copper soldering irons when they were being thrown out. As for the rest I just use a small inverter as and when required, usually when the engine is running for other reasons.

[mrsmelly]

1 hour ago, Dr Bob said:

Go back to posts 2&3. If you have a 240v fridge and need some form of stabilization for 14.2V to 12V then it's far less faffing to use 240V. The discussion then comes back to whether the OP wants the comforts of 240V devices rather than voltage changing efficiencies. I'm glad we are all different. This forum would be boring if we were all the same. 

 

Me, I like my 240V devices. 

A question for you 12V only peeps. How do you manage with soldering irons, dremmels, charging cordless drill batteries, charging cordless vacuum cleaner batteries, charging.......?

Like you I cant be arsed with 12 volt. My boat has umpteen 13 amp sockets throughout. When I bought the boat it had 12 volt fridge and 12 volt freezer. I have sold these on and replaced them with proper mains kit. Much better build quality, bigger and vastly more space not to mention the massive price difference and availability. Inverter is never switched off. Travel power for doing the heavy stuff when moving. The inverter uses 0.3 of an amp on standby and kicks in instantly on demand of fridges. The fridges being better insulated units than the crappy 12 volt stuff run for less time so real world battery useage is no different to running twelve volt kit, but way more beneficial having mains stuff as instant as in a house. I think many who say stay 12 volt are either not liveaboards or have never had a properly specced mains boat. Modern mains stuff is way more efficient than even as recently ago as ten years.

[Robbo]

 

2 hours ago, Dr Bob said:

Go back to posts 2&3. If you have a 240v fridge and need some form of stabilization for 14.2V to 12V then it's far less faffing to use 240V. The discussion then comes back to whether the OP wants the comforts of 240V devices rather than voltage changing efficiencies. I'm glad we are all different. This forum would be boring if we were all the same. 

 

Me, I like my 240V devices. 

A question for you 12V only peeps. How do you manage with soldering irons, dremmels, charging cordless drill batteries, charging cordless vacuum cleaner batteries, charging.......?

I like my DC devices, 240v is good for high current usage like microwaves, motors and heating, but these are only used for brief periods.  Majority (if not all) low current devices run on DC (I can’t think of any that are really AC).   I have a few gadgets that run 24/7 from WiFi routers to raspberry pi’s and Amazon echos, all these run from my DC system via a couple of DC/DC converters (one for 5v and another for 12v), these all average around 1amp, but if ran from the inverter they average 2amp, now that is a big difference.

Edited December 31, 2018 by Robbo

[Phil Ambrose]

2 hours ago, Dr Bob said:

Go back to posts 2&3. If you have a 240v fridge and need some form of stabilization for 14.2V to 12V then it's far less faffing to use 240V. The discussion then comes back to whether the OP wants the comforts of 240V devices rather than voltage changing efficiencies. I'm glad we are all different. This forum would be boring if we were all the same. 

 

Me, I like my 240V devices. 

A question for you 12V only peeps. How do you manage with soldering irons, dremmels, charging cordless drill batteries, charging cordless vacuum cleaner batteries, charging.......?

Got a very good 12v soldering iron, got a 12v cordless drill and so on etc

Phil

[Sea Dog]

3 hours ago, Dr Bob said:

A 12v fridge will be far less efficient and so, so, much more expensive.

The first bit is bolleaux but the second bit is correct. This is because most 12v fridges are simply commercially available domestic units converted to 12v by replacing the 240v compressor with a very good 12v unit by, most probably, Danfoss.

[dmr]

3 minutes ago, Sea Dog said:

The first bit is bolleaux but the second bit is correct. This is because most 12v fridges are simply commercially available domestic units converted to 12v by replacing the 240v compressor with a very good 12v unit by, most probably, Danfoss.

Its generally accepted that 12 volt fridges are more efficient, I think a lot of design effort went into those Danfross compressors.

Its obviously important to use nice thick wires so as not to loose the efficiency gains in cable losses.

It irritates me that the "donor" fridges for 12 volt conversion are normally the cheaper units. I know that its important to keep the price down (cus its pretty astronomic as it is) but I would rather pay even more and have a really good fridge...why put such a lovely compressor into a crap fridge?.  I do wonder if an upmarket 240 volt fridge would have better insulation and so offset some of the efficiency gain of the 12 volt units?????

 

...............Dave

 

[cuthound]

Buying a 240 volt fridge or freezer and paying a fridge "engineer" to replace the compressor with a 12 volt Danfoss one is way cheaper than buying a dedicated 12 volt one and gets you a well insulated cabinet with modern features. 

 

Compromises the warranty though.

[Dr Bob]

3 hours ago, Sea Dog said:

The first bit is bolleaux but the second bit is correct. This is because most 12v fridges are simply commercially available domestic units converted to 12v by replacing the 240v compressor with a very good 12v unit by, most probably, Danfoss.

Well I'm confused. My new 2017 cheapo 240V exlectrolux (or wotever) is an A+ and uses 30 ish Ahr per 24hrs in the summer - maybe 10Ahr more in that really hot weather last summer. The latest Shoreline doesnt give a efficiency rating but instead gives an estimated 53Ahrs usage in 24 hrs.

https://www.elyboatchandlers.com/shoreline/ff2022-shoreline-88l-under-counter-12v/24v-boat-fridge-freezer

Not a clue what conditions that is measured over but our 240V is nowhere near that much. Maybe we have ours sited in a better environment - decent air circulation. Ours was £400 squid less than the Shoreline.

What power are your 12V or 240V fridges taking?

From memory our fridge takes 3.5A when the compressor comes on but not a clue about the cycle time (on/off) but it works out just over one 1/3rd of the time ish.

[Alan de Enfield]

9 minutes ago, Dr Bob said:

What power are your 12V or 240V fridges taking?

My 12v Waeco fridge is about 25-30Ah per day (depending on number of door openings, ambient temp etc)

My 230v Argos Freezer is around 40-45Ah per day + inverter at around 2a (48Ah per day)

[dmr]

24 minutes ago, Dr Bob said:

Well I'm confused. My new 2017 cheapo 240V exlectrolux (or wotever) is an A+ and uses 30 ish Ahr per 24hrs in the summer - maybe 10Ahr more in that really hot weather last summer. The latest Shoreline doesnt give a efficiency rating but instead gives an estimated 53Ahrs usage in 24 hrs.

https://www.elyboatchandlers.com/shoreline/ff2022-shoreline-88l-under-counter-12v/24v-boat-fridge-freezer

Not a clue what conditions that is measured over but our 240V is nowhere near that much. Maybe we have ours sited in a better environment - decent air circulation. Ours was £400 squid less than the Shoreline.

What power are your 12V or 240V fridges taking?

From memory our fridge takes 3.5A when the compressor comes on but not a clue about the cycle time (on/off) but it works out just over one 1/3rd of the time ish.

 

Where did you get this figure, was it in a data sheet or did you measure it?   It sounds a bit low.

 

.............Dave

[Dr Bob]

26 minutes ago, dmr said:

 

Where did you get this figure, was it in a data sheet or did you measure it?   It sounds a bit low.

 

.............Dave

From a power audit the first summer we got the boat. Not got the figures to hand...they are on the boat which is away being painted. The 3.5A is the measured value.