Battery Charger vs Converter

[DDOK]

Newbie question here:

What's the difference between a converter, and a battery charger like this one:

30 Amp 12 Volt Battery Charger *UL Listed* | SEC-1230UL

Can converters usually run your 12 volt system while charging your batteries, but battery chargers can't (although the samlex above appears to be able to do both)?

I get the differences between an inverter and a converter, but the differences between battery charger and converter seem a little more confusing.

Thanks,

DD

[ROBERT CROSS]

This statement in the product description.....
"Charge with a battery load or stand alone."

Sez to me that its a 'converter' and will supply 12v with no battery in the loop, something I wouldn't try with a 'battery charger".

Bob

[rodsterinfl]

Battery Chargers are usually lower output as they have limitations using 120v supply. I have a charger for storage that is 6 amps. It takes up to 30 hours or so to charge up my batteries but that is ok since it is a smart charger and its purpose is to keep the batteries up (I went to solar last spring for this purpose) while the larger charger/converter unit in the trailer charges at a much higher rate. Mine claims to charge the batteries from 50% in 3 hours I believe. Compare that to the 120V model. The conversion part is that it uses power to provide AC and DC power to trailer systems as there are both. My converter is 55 amps. In auto stores, for example, chargers recommended are 1.1 amp to 6 amp for a single battery and will do more if time is not an issue. The intent is small lightweight, etc.

I can use my DC powered accessories while on a battery charger. It will simply charge at whatever rate it charges and my usage will draw whatever. I will not have AC accessory power unless using an inverter.

[DDOK]

Thanks guys. I think what was throwing me off was that the Samlex in the link was listed as a 'battery charger' but I think it's really more of a converter.

[blkmagikca]

The Samlux SEC-1230UL output is only 30 amps according to their specifications - by comparison, the maximum charge output of the Xantrex Freedom 3012 installed in my AS is 150 amps.

[55AS]

Originally Posted by blkmagikca

The Samlux SEC-1230UL output is only 30 amps according to their specifications - by comparison, the maximum charge output of the Xantrex Freedom 3012 installed in my AS is 150 amps.

50 Amp 12 Volt Battery Charger *UL Listed* | SEC -1250UL

[Inland RV Center, In]

Originally Posted by DDOK

Newbie question here:

What's the difference between a converter, and a battery charger like this one:

30 Amp 12 Volt Battery Charger *UL Listed* | SEC-1230UL

Can converters usually run your 12 volt system while charging your batteries, but battery chargers can't (although the samlex above appears to be able to do both)?

I get the differences between an inverter and a converter, but the differences between battery charger and converter seem a little more confusing.

Thanks,

DD

A battery charger puts out a small amount of current, that also does not have a brain, meaning a charger does not know when to back off the charging rate. End result is if you don't disconnect it when the battery is fully charged, it will ruin the battery.

A converter on the other hand, has a brain, and knows when to back off the charging rate, meaning if you leave it on continuously, it will not hurt the battery. RV's never use a battery charger, but they do use a converter.

By definition, a converter changes the city power, which is 120 volts AC, down to a DC voltage that slightly varies around 12 to 14 volts, depending on the battery condition. An inverter, does exactly the opposite of a converter, in that it takes the battery voltage which is pure DC electronically chops it into 60 cycles and with a transformer, step the voltage up to city power, which is 120 volts AC.

The problem with converters, assuming 100 percent efficiency, is the amount of DC current it requires. As an example, if you wanted to have as little as 10 amperes output from a converter, it would require an input current of at least 100 (one hundred) amps, again assuming 100 percent efficiency, but in reality it's closer to 75 percent, therefore the input current draw for those 10 amps @ 120 volts AC would increase to 133.34 amps @ 12 volts DC. That means one fully charged 12 volt battery would last maybe 15 minutes, or so. But that could easily be rectified if you had about 20 or more big batteries in the trailer. NOT

A inverter in an RV, has it's purpose, but only for very small current requirements, and for a very short time.

Household items such as a hair drier, coffee pots, toasters, deep fat fryers, and the like, are all left at home, if your going to operate self contained. If the coach will be pluged into city power, then and only then can you use those heavy wattage demand items.

A 50 amp converter is about the best size converter to use. Anything with a higher current output basically, is a waste of money. Since your camping, "what's the hurry" ?

Andy

[DDOK]

Hah! BlkMagika - You could run an arc welder off that thing :-) Also, it's $1500 which is a little steep for me.

Seriously though - Point well taken on the Amps. I think I'd probably want to bump it up to at least the 50 amp that BambiTex listed so that I can run my air conditioner and a microwave and maybe a few lights....

--DD

[TouringDan]

Originally Posted by Inland RV Center, In

The problem with converters, assuming 100 percent efficiency, is the amount of DC current it requires. As an example, if you wanted to have as little as 10 amperes output from a converter, it would require an input current of at least 100 (one hundred) amps, again assuming 100 percent efficiency, but in reality it's closer to 75 percent, therefore the input current draw for those 10 amps @ 120 volts AC would increase to 133.34 amps @ 12 volts DC. That means one fully charged 12 volt battery would last maybe 15 minutes, or so. But that could easily be rectified if you had about 20 or more big batteries in the trailer. [B]NOT[/B

Andy

You are describing an inverter, not a converter.

Dan

[blkmagikca]

Originally Posted by DDOK

Hah! BlkMagika - You could run an arc welder off that thing :-) Also, it's $1500 which is a little steep for me.

Seriously though - Point well taken on the Amps. I think I'd probably want to bump it up to at least the 50 amp that BambiTex listed so that I can run my air conditioner and a microwave and maybe a few lights....

--DD

Actually, no. It's a safety margin you hope never to exceed.

My setup is ine to necessary as I run a CPAP machine for my obstructive sleep apnea - that machine has a heater in it for the humidifyer. I had JC complete my install when I changed my batteries. In the photo you can see the two size 4D AGM batteries (totalling 420 Amp-Hrs) with the Xantrex FS3012 in between.

[blkmagikca]

This photo was taken at JC when the work was in progress. The original battery compartments and doors were removed; two stainless steel battery trays for the 4D-size batteries were bolted through the floor into the frame. The outer skin (the "plate") - the panel that runs across the front under the window, was replaced - no cut-outs for any battery doors - and a frame segment was added. The inner skin was patched with insulation between the inner and outer skins. The quality of workmanship is superb at JC.

[Rich W]

Originally Posted by rodsterinfl

Battery Chargers are usually lower output as they have limitations using 120v supply.

On board battery chargers for bass boats are fairly powerful. I have a 3-bank Pro Charger for my 2-trolling motor and ignition batteries. Each bank is independent of the others and does 15 amps with a total shutoff when they are charged.

I got mine back in the 90s, paid about $250 for it, still going strong. They are called Tri (Dual) Pro now and are $350 on Amazon today, down from $450

[DWG-77]

Hi all,

I have a question that I think I know the answer to but would really appreciate some advice on replacing the original converter on the 1977 21' Globetrotter I just purchased.
We purchased the trailer which the previous owner had started the renovation on. He gave us a:

Schumacher Model SSF-1000A Ship’n Shore Speed Charger

which he was planning on using to replace the original converter.

Correct me if I am wrong but I do not believe that this charger is what we need to replace the old converter.

Our plans for the trailer are to use it at campsites with shore power access so I was planning on having a single 12v battery.

My understanding is that I will need a converter not a charger so I am assuming that I will have to buy one and find another use for this battery charger.

Any advice on whether I am correct on this would be greatly appreciated along with recommendations on what type of converter to purchase based on the assumption that our trailer will be used with Shore power access.

[richard5933]

A converter/charger is what you need. Usually we refer to these as converters, but they have both converter functions and charger functions.

A charger like the one you were given is designed for use to charge batteries, but it is not designed to operate without batteries like most converter/chargers are. Another difference is likely that the charger won't be able to automatically adjust to increased usage from things like an inverter.

Most converter chargers combine multi-stage charging functions with a 120vac-to-12vdc converter which can be used without batteries if necessary and will be able to duck and roll as the devices like an inverter, fans, lighting, etc. draw from the battery bank.

All that said, I do carry a small charger like you're describing for emergency situations, especially for times when the TV battery needs a charge.

[TouringDan]

I recommend you purchase either a 45 or 60 amp converter from Progressive Dynamics. They are about $200 from Amazon, made in America and very reliable and easy to install. Mine is 10 years old with no problems.

Dan

[DWG-77]

Thanks for your response. Basically confirmed what I suspected.

[bigrig]

2005 19' Bambi: installed new batteries (fully charged) - shore power works fine, but no power when on DC power. Converter issue? Does converter have a reset button?
Thanks.

[richard5933]

Originally Posted by bigrig

2005 19' Bambi: installed new batteries (fully charged) - shore power works fine, but no power when on DC power. Converter issue? Does converter have a reset button?
Thanks.

By "no power when on DC power" do you mean. when you're unplugged from shore power? If so, your converter has nothing to do with operating when you're not plugged in.

Where are you trying to get power when you're on DC power? The lights, water pump, fridge, furnace, and water heater should work on DC (assuming propane is on/working). However, none of the outlets will work, the a/c will not work, and the microwave will not work.

What are you trying to operate on DC which has no power?

[Ephraim]

Originally Posted by rodsterinfl

Battery Chargers are usually lower output as they have limitations using 120v supply. I have a charger for storage that is 6 amps. It takes up to 30 hours or so to charge up my batteries but that is ok since it is a smart charger and its purpose is to keep the batteries up (I went to solar last spring for this purpose) while the larger charger/converter unit in the trailer charges at a much higher rate. Mine claims to charge the batteries from 50% in 3 hours I believe. Compare that to the 120V model. The conversion part is that it uses power to provide AC and DC power to trailer systems as there are both. My converter is 55 amps. In auto stores, for example, chargers recommended are 1.1 amp to 6 amp for a single battery and will do more if time is not an issue. The intent is small lightweight, etc.

I can use my DC powered accessories while on a battery charger. It will simply charge at whatever rate it charges and my usage will draw whatever. I will not have AC accessory power unless using an inverter.

A chargers main function is to provide optimal charging to the battery and a converters job is to provide dc to run things.

There is some crossover in functionality but a charger will typically proved a 3 or 4 stage charging capability. A converter will generally provide a constant voltage. Any more the names are used interchangeably as the single voltage system has fallen out of favor since multistage chargers are so easy to produce.

Where you will find the biggest difference is how the charger acts like a converter. The better ones will provide the heavy current to run your trailer while in ANY stage of charging. The next level down will monitor the battery and shift into bulk/absorption charge when the battery voltage drops to low. Otherwise it lets the battery do the work.

[SHaley]

#19 Is the best answer yet.
Did you see in section 8 what you have to do to hook the unit up as a power supply.
Automotive Chargers started out as 6vdc then 12v, so chargers and they way they operate have changed a lot. My 90 AS just uses a converter, 12vdc constant current power supply hooked to the batteries as a charger. The LO bought new batteries in 2016 and they are still good.