AC to DC Charger Specifications

[bajajoaquin]

I’m looking at AC to DC chargers to replace the one that’s in my ‘99 RV and I have a question about how they are labeled. Does a “35 amp” charger have 35 amps on the input (110) side or the output (12v) side?

I ask because my camper has 30a service so it would make sense to save a few bucks by buying a 35a charger rather than a 55a model, right?

 

[schmism]

My understanding is that is a 35amp 12v charger or about 420w

 

[Alphacarina]

Yes, it's 35 amps at 12 volts. If it was at 120 volts, your old 55 amp charger would pop your 30 ampm breaker every time you turned it on

Don

 

[bajajoaquin]

30 amps is the 110 service. But if it’s the output amps, then 55amps is no issue at all since 55 amps at 12v converts to 6 amps at 110.

 

[time2roll]

May as well post the '99 RV converter model number. Some are lousy and some are great.

Don't get too wrapped up in the "lithium" models with a DIY battery as they will be prone to charging all the way to battery shut down. Many normal converters are actually better IMO with limiting volts to 14.4.

Before you go larger than OEM, a review of the charging loop needs to be made to avoid overload or blow a fuse.

 

[bajajoaquin]

I’ll go to the camper tomorrow so I’ll have a chance to see the model number then.

To clarify: I’m not saying it has a 35 amp charger, I’m saying it has 30 amp shore power service. If the chargers were described by the input power, then it made no sense to spend an extra $100 for a 55 amp charger if it was only ever going to see 30 amps of input. However, since it’s output, I’ll see what is there before making decisions.

 

[NVS]

If you change the converter to a higher amps you will need to change the wire size to the batteries as well.

 

[schmism]

based on the power center thingie in my RV (when I had one) the plug was 30amp AC 120v. however the charger side of the DC was only 35a.

It would pass 120v through to the plugs in the RV (and run the rooftop air on 120v) however the 35amp part was the DC side. (12v fridge, charger overhead lights, fans etc)

 

[bajajoaquin]

Took me a while to get to it, but the charger is an Intellipower 9140A.

Opinions on whether this is compatible with LiFeSO4?

 

[John Frum]

Took me a while to get to it, but the charger is an Intellipower 9140A.

Opinions on whether this is compatible with LiFeSO4?

Home 3 - Progressive Dynamics

The Mighty Mini Compact All-In-One System offers an AC/DC Power Distribution Panel and Inteli-Power Converter with Charge Wizard battery charging technology.

www.progressivedyn.com

Seems to be a 1 stage charger otherwise known as a constant voltage constant current power supply.
Voltage of 13.6 volts is too low to charge your batteries quickly and a tiny bit high to float them for extended periods.

Will this be your primary method of charging your battery?
Personally I would be ok with using this as a backup solution.

UPDATE: doco mentions TCMS might be more going on.

Home 3 - Progressive Dynamics

The Mighty Mini Compact All-In-One System offers an AC/DC Power Distribution Panel and Inteli-Power Converter with Charge Wizard battery charging technology.

www.progressivedyn.com

 

[Sback]

With most of the new ac dc converter charger if you are plugged into a 110 outlet it will only charge at 15 amps, no matter what the size is.I believe they have what's called load sharing sensing technology, meaning your converter will not rob all the ac power when other ac devices are being used. Unless you do alot of camping at a rv park with rv hookups you will never see over 15amps charging. Most of us just plug into are 110 outlet so buying a larger ac dc converter is realy a waste of money.

 

[John Frum]

With most of the new ac dc converter charger if you are plugged into a 110 outlet it will only charge at 15 amps, no matter what the size is.I believe they have what's called load sharing sensing technology, meaning your converter will not rob all the ac power when other ac devices are being used. Unless you do alot of camping at a rv park with rv hookups you will never see over 15amps charging. Most of us just plug into are 110 outlet so buying a larger ac dc converter is realy a waste of money.

I have a powermax and an iota, neither of mine work as you describe.

 

[time2roll]

Took me a while to get to it, but the charger is an Intellipower 9140A.

Opinions on whether this is compatible with LiFeSO4?

9140 will serve you well. Although by itself it charges at a fixed 13.6 volts and you would benefit from adding the Charge Wizard. The Wizard takes voltage to 14.4 before dropping to 13.6 after a few hours. With minimal use the Wizard will drop voltage to 13.2 in 3 to 7 days for storage.

https://www.bestconverter.com/Charge-Wizard

For faster charging a 9180 or 9280 (includes wizard) would provide twice the power.

Be careful looking at the "lithium" converters as most go all the way to 14.6 volts and will probably shut down a DIY battery for over volt at the cell level. A few even hold 14.6 indefinitely and I can't recommend this.

 

[bajajoaquin]

Great, thanks! I’ll look into the wizard.

In any case, nothing needs to be done for the trip I have coming up. AC (generator or shore power) isn’t likely to be a big part of my power mix so it can just give me a few Ah if it’s cloudy.

 

[John Frum]

Great, thanks! I’ll look into the wizard.

In any case, nothing needs to be done for the trip I have coming up. AC (generator or shore power) isn’t likely to be a big part of my power mix so it can just give me a few Ah if it’s cloudy.

For a secondary charge source I wouldn't even worry about the wizard.
If it was me I would remove the cover and look for a trim potentiometer.
I'd set the voltage to 13.4 volts, making it safe to leave on indefinitely.

 

[bajajoaquin]

It’s “secondary” in the sense that it’s not my majority use case. But that’s because my camper trips are really bifurcated into two really different types of trips. On the one hand, I go to Baja where I camp for a week or 10 days (sigh, the days of 2+ weeks are behind me) in remote places. No services but lots of sun.

On the other hand, we take trips to the local mountains and up the pacific coast where we camp in wooded campgrounds. Lots of services but little reliable sun.

So for the next (first in this camper) trip, I’ll be in Baja for a week and I’m counting on the new solar system working. If not I’ll make do with inefficient generator power.

Although for $30, I might just order one and be done with it.

We’ll see. Even a small job can be a problem if there are enough other small jobs to do.

 

[bajajoaquin]

I asked about the wizard compatibility with my charger and they didn’t answer that question but said this instead:

“
Hello,

You can add the PD9105 for charging lithium batteries.

You will just have to remember to press the button each time you want to charge the lithium batteries.

Each time you press the button, you will get 4 hours of charging at 14.6 volts. After 4 hours the converter will drop back down to a 13.6 volt output.



If you don’t want to press the button each time you want to charge, then you could add our 14.6 TCMS module.

Once you connect the TCMS module to the converter, you will have a constant output voltage of 14.6. no need to worry about pressing the button. The unit does not drop back down to 13.6”

Is it okay to charge lithium batteries at 14.6 constantly with no float?

 

[John Frum]

Is it okay to charge lithium batteries at 14.6 constantly with no float?

No.
Exposing a 12 volt lifepo4 battery to greater than 13.4 volts is stressful.
Its a required stress in order to charge the battery but once the battery is charged the its just unnecessary stress.
It will shorten your battery's life.
Also 14.6 is the the maximum allowable charge voltage possible and you will very likely trip the battery's bms on every charge.
You can charge a battery full quite effectively with 13.7-14.2 volts.
I'm surprised they didn't try and sell you a new "lithium" converter.

If you have not already purchased an inverter I suggest you get an inverter/charger.
If you are interested I can tell you why I think its the best solution.

 

[bajajoaquin]

Absolutely!

I’d planned on getting a new charger but thought I could buy the wizard instead. So I’m back to getting a charger. An inverter is also on my list, but farther down. I don’t have a lot of inverter needs so I’d probably just buy one that will power my microwave for occasional use. It’s a 700w model so a 1000w or 1500w would probably be fine.

But please, I’m all ears!

 

[John Frum]

Absolutely!

I’d planned on getting a new charger but thought I could buy the wizard instead. So I’m back to getting a charger. An inverter is also on my list, but farther down. I don’t have a lot of inverter needs so I’d probably just buy one that will power my microwave for occasional use. It’s a 700w model so a 1000w or 1500w would probably be fine.

But please, I’m all ears!

Inverter/chargers combine and inverter, charger and automatic transfer switch.

Discrete inverters have gotten just about zero RnD since the the inverter/charger has eaten it's lunch.
Its even worse for RV converters, even the "lithium" converters are a joke.

The killer feature that inverter/chargers have is an embedded computer which allows for lots of features and granular configuration.
The most important for is the charge profile.
Typically you can choose the charge voltage, charge termination policy and float voltage.
The second most important bit is low voltage disconnect.
That means your inverter can stop inverting before the BMS has to disconnect the battery.
The BMS protects the battery and the inverter/charger protects the BMS.
Also the automatic transfer switch in an inverter/charger makes sure the ac current is synchronized before switching so that even your most sensitive loads won't even notice a thing.
With a olds style automatic transfer switches you will probably have to reset the clock on your microwave every time you switch power sources.

Finally discrete chargers are almost always high frequency which means their surge capacity is 2x for 20 milli seconds which is only important to the marketing department.
Most inverter/chargers are low frequency with a big honking iron transformer, these have surge capacity often rated in minutes.

Inverter/chargers cost more but they are better.
If you need 2 or more of inverter or charger or automatic transfer switch I suggest an inverter/charger is the way to go.