Hi, I use a 240v to 12v transformer to run my 12v lights, water pump, toilet, winegaurd etc. My question is, is this okay or should I use a step down fro m 24v to 12v.
My coach has 4 X 175 panels (24v), 2 X 12v - 210 amp AGM's and 1000W inverter. The only 240v appliances we run are TV, microwave, domestic fridge, extractor fan in bathroom, CPAP machine.
My system will not run my air cons. Would a bigger inverter help this, or more batteries.
John
2foot6 said
10:50 AM Feb 9, 2014
Hi John.using an inverter and a step down transformer you have two areas for losses of power in the circuitry .I would invest in a 24v-12v converter to run your low power 12v appliances and perhaps change the exhaust fan for a 12v unit.When using batteries any savings are a plus, are you using LED lighting,as there is a great saving there? Cheers Peter.
-- Edited by 2foot6 on Sunday 9th of February 2014 10:52:57 AM
-- Edited by 2foot6 on Sunday 9th of February 2014 10:53:17 AM
learmo said
11:06 AM Feb 9, 2014
Thanks Peter, yes all LED lights.
Phil C said
11:49 AM Feb 9, 2014
You cant transform DC. 24 to 12 needs some fancy electronics called a DC to DC converter, just not worth the effort
You will need a very large inverter to run an aircon, I have some 8 inch 12V DC fans in my van they are OK on "most" hot nights. Running an aircon on an inverter will drain any battery bank fast, you may need 4 110AH batteries to get close to a full night, especially if the inverter cuts out at 10 odd volts.
My suggestion is to get at least a 2KVA generator (3KVA to be sure) that will run your aircon.
Safe travels.
BTW I would run all 12VDC gear direct from the battery, the solar stuff should be only charging the battery bank. FYI inverters draw a lot out of a battery bank even at low loads, we have a 3000W inverter and only run low end stuff at night. Im an advocate for the generator, sorry folks they work much better than inverters even though they have one on board, the trick is they will not flatten your battery bank.
-- Edited by Phil C on Sunday 9th of February 2014 11:54:47 AM
oldbobsbus said
01:01 PM Feb 9, 2014
Phil C wrote:
You cant transform DC. 24 to 12 needs some fancy electronics called a DC to DC converter, just not worth the effort
Thats not correct I use THESE and they work perfectly and have done for 2 years so for without a problem..
I also use a slightly larger one (10a) to run my water pump..
powerstream said
01:15 PM Feb 9, 2014
John
You have a 24V vehicle and rightly have a 24V house bank to allow charge while driving but you mainly run 12 volt so the best way to get maximum efficiency would be to use a BB241230 Battery charger from your cranking battery to your house bank which you convert to 2x batteries in parallel for 12V then configure your solar into 12V.
The BB241230 uses the same algorithms as a mains charger and can take your batteries to a higher state of charge than a standard alternator increasing your useable battery capacity.
You will still need to look to a generator to run your air con due to the type of unit it is but with Inverter air cons there are instances where they can run off batteries due to the greatly reduced power demand.
DC/DC Chargers are currently successfully driving DC air con systems in trucks but this is in a cabin area not a motorhome.
Ian
Phil C said
01:34 PM Feb 9, 2014
My apologies, I forgot about the newer battery chargers.. oopps living in the past..
learmo said
02:23 PM Feb 9, 2014
Thanks powerstream, I just looks these up on the net. I have 24v solar panels, 2 X 210 amp batteries in series, and 24v inverter. Will that charger still work?
John
powerstream said
02:40 PM Feb 9, 2014
Sorry John I missed the inverter and no it is 24V and am saying convert to 12V so no that will create an added cost. How long have you been on the Transformer and is it still doing the job because if its not broken then leave it alone as the cheapest fix is to do what Phil stated get a generator to run the air con. If and when you find that what you have is not sufficient for your needs or is broken then look to a potential upgrade for your system. But one further question how big is your alternator. Ian
-- Edited by powerstream on Sunday 9th of February 2014 02:41:05 PM
learmo said
02:51 PM Feb 9, 2014
At the moment my alternator is not hooked up to the house batteries. I relocated the house batteries and inverter, and need to run about 3 metres of cable to the smart charger.
The 240v -12v transformer has been in about 1 year.
I would connect the alternator to the smart charger to see what capacity gain I achieved but that would be limited to when you travelled as the more your travelled the better the gain so really you appear to be more reliant on the solar so does your use allow the solar to recover the batteries for you and do they get into float and if so at what time of the day.
This is just to see how things are panning out for you at the moment and to determine if your only shortfall is air conditioner use.
Ian
learmo said
07:19 PM Feb 9, 2014
Batteries are usually topped up by midday, unless overcast. If day is overcast I run out of battery.
brian said
07:20 PM Feb 9, 2014
learmo wrote:
Batteries are usually topped up by midday, unless overcast. If day is overcast I run out of battery.
How do you determine that they are "topped up"?
learmo said
07:22 PM Feb 9, 2014
I go by the reading on the P40 controller
powerstream said
08:11 PM Feb 9, 2014
John
So if that is the Plasmatronic PL 40 that is fine and that brings down the conversion cost as it is settable for either 12V or 24V if and when you desire to do it.
Ian
baysidetas said
12:36 AM May 10, 2014
oldbobsbus
Bob you cannot use a TRANSFORMER to change a DC voltage/current but you can use a CONVERTER to achieve that. If you look at the items in the link you posted you will see they are labelled as a CONVERTER.
Maybe I am being a bit pedantic but using the correct terms may avoid confusion.
dorian said
07:43 AM May 10, 2014
baysidetas wrote:
oldbobsbus
Bob you cannot use a TRANSFORMER to change a DC voltage/current but you can use a CONVERTER to achieve that. If you look at the items in the link you posted you will see they are labelled as a CONVERTER.
Maybe I am being a bit pedantic but using the correct terms may avoid confusion.
No, you are not being pedantic. There is a BIG difference between an AC-to-AC transformer and a DC-to-DC converter.
native pepper said
10:20 AM May 10, 2014
learmo wrote:
Hi, I use a 240v to 12v transformer to run my 12v lights, water pump, toilet, winegaurd etc. My question is, is this okay or should I use a step down fro m 24v to 12v.
My coach has 4 X 175 panels (24v), 2 X 12v - 210 amp AGM's and 1000W inverter. The only 240v appliances we run are TV, microwave, domestic fridge, extractor fan in bathroom, CPAP machine.
My system will not run my air cons. Would a bigger inverter help this, or more batteries.
John
G'day John, we've had a few 24v buses over the years and found the best set up for us is a follows.
We have 710w of solar,(1000w coming up soon), 250w is 24v and they all run through a 30amp MPPT into a 200AH lifepo4 bank. Our start batteries are connected via a redarc to 60amp AGM 24v bank and from their through a 60amp 24v-12v DC converter and into our lifepo4.
This means we can charge our transfer batteries and house batteries whilst travelling, then switch the 250w 24v panel to keep the start and transfer batteries charged when stopped, or keep them on the house system. All this operates on 3 way switches.
The only appliances we use on 240v is a big TV, everything else is 12v and LED lighting, changed all the bus lights to LED, except headlights and we never run out of power, even after 4-5 days of no sun we are fine.
We have HE and 12v hot water, backed up with solar, this reduces the need for power and the hot water can also be heated with 240v if we have mains power. We only use a 1000w inverter and always carry at least 2 spares of everything electrical.
If you're going to update your system go for the simplest and most versatile one you can come up with, the more options for charging and reduction of power lose you can come up with, makes life on the road so much easier and safer.
Make sure you have the right cabling size, ran across many people with 12v fridges who are having troubles with them. Most times it turns out they have to small cabling for providing the kick start fridges need. Cabling is another expense you can reduce by using the right size for individual appliance connections, our bus has different cabling for different things, which reduces lose and provides the needed power for what it drives.
oldbobsbus said
03:46 PM May 10, 2014
dorian wrote:
baysidetas wrote:
oldbobsbus
Bob you cannot use a TRANSFORMER to change a DC voltage/current but you can use a CONVERTER to achieve that. If you look at the items in the link you posted you will see they are labelled as a CONVERTER.
Maybe I am being a bit pedantic but using the correct terms may avoid confusion.
No, you are not being pedantic. There is a BIG difference between an AC-to-AC transformer and a DC-to-DC converter.
Just point out to me where I said they were a TRANSFORMER....
baysidetas said
06:33 PM May 10, 2014
oldbobsbus
That is the way I read your posting of 9 Feb - seems I mis understood what you wrote.
-- Edited by baysidetas on Saturday 10th of May 2014 06:34:58 PM
Hi, I use a 240v to 12v transformer to run my 12v lights, water pump, toilet, winegaurd etc. My question is, is this okay or should I use a step down fro m 24v to 12v.
My coach has 4 X 175 panels (24v), 2 X 12v - 210 amp AGM's and 1000W inverter. The only 240v appliances we run are TV, microwave, domestic fridge, extractor fan in bathroom, CPAP machine.
My system will not run my air cons. Would a bigger inverter help this, or more batteries.
John
Hi John.using an inverter and a step down transformer you have two areas for losses of power in the circuitry .I would invest in a 24v-12v converter to run your low power 12v appliances and perhaps change the exhaust fan for a 12v unit.When using batteries any savings are a plus, are you using LED lighting,as there is a great saving there? Cheers Peter.
-- Edited by 2foot6 on Sunday 9th of February 2014 10:52:57 AM
-- Edited by 2foot6 on Sunday 9th of February 2014 10:53:17 AM
Thanks Peter, yes all LED lights.
You cant transform DC. 24 to 12 needs some fancy electronics called a DC to DC converter, just not worth the effort
You will need a very large inverter to run an aircon, I have some 8 inch 12V DC fans in my van they are OK on "most" hot nights. Running an aircon on an inverter will drain any battery bank fast, you may need 4 110AH batteries to get close to a full night, especially if the inverter cuts out at 10 odd volts.
My suggestion is to get at least a 2KVA generator (3KVA to be sure) that will run your aircon.
Safe travels.
BTW I would run all 12VDC gear direct from the battery, the solar stuff should be only charging the battery bank. FYI inverters draw a lot out of a battery bank even at low loads, we have a 3000W inverter and only run low end stuff at night. Im an advocate for the generator, sorry folks they work much better than inverters even though they have one on board, the trick is they will not flatten your battery bank.
-- Edited by Phil C on Sunday 9th of February 2014 11:54:47 AM
Thats not correct I use THESE and they work perfectly and have done for 2 years so for without a problem..
I also use a slightly larger one (10a) to run my water pump..
You have a 24V vehicle and rightly have a 24V house bank to allow charge while driving but you mainly run 12 volt so the best way to get maximum efficiency would be to use a BB241230 Battery charger from your cranking battery to your house bank which you convert to 2x batteries in parallel for 12V then configure your solar into 12V.
The BB241230 uses the same algorithms as a mains charger and can take your batteries to a higher state of charge than a standard alternator increasing your useable battery capacity.
You will still need to look to a generator to run your air con due to the type of unit it is but with Inverter air cons there are instances where they can run off batteries due to the greatly reduced power demand.
DC/DC Chargers are currently successfully driving DC air con systems in trucks but this is in a cabin area not a motorhome.
Ian
My apologies, I forgot about the newer battery chargers.. oopps living in the past..
Thanks powerstream, I just looks these up on the net. I have 24v solar panels, 2 X 210 amp batteries in series, and 24v inverter. Will that charger still work?
John
Sorry John
I missed the inverter and no it is 24V and am saying convert to 12V so no that will create an added cost.
How long have you been on the Transformer and is it still doing the job because if its not broken then leave it alone as the cheapest fix is to do what Phil stated get a generator to run the air con.
If and when you find that what you have is not sufficient for your needs or is broken then look to a potential upgrade for your system.
But one further question how big is your alternator.
Ian
-- Edited by powerstream on Sunday 9th of February 2014 02:41:05 PM
At the moment my alternator is not hooked up to the house batteries. I relocated the house batteries and inverter, and need to run about 3 metres of cable to the smart charger.
The 240v -12v transformer has been in about 1 year.
This is just to see how things are panning out for you at the moment and to determine if your only shortfall is air conditioner use.
Ian
Batteries are usually topped up by midday, unless overcast. If day is overcast I run out of battery.
How do you determine that they are "topped up"?
I go by the reading on the P40 controller
So if that is the Plasmatronic PL 40 that is fine and that brings down the conversion cost as it is settable for either 12V or 24V if and when you desire to do it.
Ian
Bob you cannot use a TRANSFORMER to change a DC voltage/current but you can use a CONVERTER to achieve that. If you look at the items in the link you posted you will see they are labelled as a CONVERTER.
Maybe I am being a bit pedantic but using the correct terms may avoid confusion.
No, you are not being pedantic. There is a BIG difference between an AC-to-AC transformer and a DC-to-DC converter.
G'day John, we've had a few 24v buses over the years and found the best set up for us is a follows.
We have 710w of solar,(1000w coming up soon), 250w is 24v and they all run through a 30amp MPPT into a 200AH lifepo4 bank. Our start batteries are connected via a redarc to 60amp AGM 24v bank and from their through a 60amp 24v-12v DC converter and into our lifepo4.
This means we can charge our transfer batteries and house batteries whilst travelling, then switch the 250w 24v panel to keep the start and transfer batteries charged when stopped, or keep them on the house system. All this operates on 3 way switches.
The only appliances we use on 240v is a big TV, everything else is 12v and LED lighting, changed all the bus lights to LED, except headlights and we never run out of power, even after 4-5 days of no sun we are fine.
We have HE and 12v hot water, backed up with solar, this reduces the need for power and the hot water can also be heated with 240v if we have mains power. We only use a 1000w inverter and always carry at least 2 spares of everything electrical.
If you're going to update your system go for the simplest and most versatile one you can come up with, the more options for charging and reduction of power lose you can come up with, makes life on the road so much easier and safer.
Make sure you have the right cabling size, ran across many people with 12v fridges who are having troubles with them. Most times it turns out they have to small cabling for providing the kick start fridges need. Cabling is another expense you can reduce by using the right size for individual appliance connections, our bus has different cabling for different things, which reduces lose and provides the needed power for what it drives.
Just point out to me where I said they were a TRANSFORMER....
oldbobsbus
That is the way I read your posting of 9 Feb - seems I mis understood what you wrote.
-- Edited by baysidetas on Saturday 10th of May 2014 06:34:58 PM