Do I need to a converter if using a battery charger

[ScottP101]

Hello, my converter just died and I was wondering if I needed to replace it, or if I could just hook up my NOCO 5AH battery charger and it would do the same thing. I just did this on my last camping trip where I used an extension cord to plug in my battery charger the whole time while my battery ran all the 12v systems. I was wondering if there is a long term issue doing this, and/or if the converter does other things I'm not aware of that I need. I generally dry camp, so connecting to shore power only happens once or twice a year, so I'm considering not replacing the converter. Thanks!

 

[AudiDudi]

Your converter is likely at least 55A. How many AH of batteries do you have and are they FLA Or Lithium? If you're boondocking, how will you plug in your charger? If lithium, does your charger put out enough voltage to fully charge them?

 

[D W]

The problem I see is when you're dry camping what is going to charge the battery? Without shore power to run your charger, it won't take long to run the battery down.

 

[TitanMike]

If you mainly dry camp I would strongly recommend replacing the converter. A five amp battery charger will most likely not keep up with power use long term.

It's usually recommended that converter/chargers be at least the same output as 25% of the total battery storage capacity.

 

[ScottP101]

Your converter is likely at least 55A. How many AH of batteries do you have and are they FLA Or Lithium? If you're boondocking, how will you plug in your charger? If lithium, does your charger put out enough voltage to fully charge them?

I just have one 100ah lithium battery. I also have a 200 watt solar panel that I'll hook up if needed. I figured when I'm boondocking I won't have shore power either, so it's more of a question of when I'm hooked up to a place with shore power, can I just use my battery charger instead of the converter.

 

[ScottP101]

The problem I see is when you're dry camping what is going to charge the battery? Without shore power to run your charger, it won't take long to run the battery down.

I have a 200 watt solar panel to help keep it charged. And we don't run the heater or other high energy needy appliances when boondocking so we're normally okay on that front, so my question was mainly about when I'm connected to shore power.

 

[ScottP101]

If you mainly dry camp I would strongly recommend replacing the converter. A five amp battery charger will most likely not keep up with power use long term.

It's usually recommended that converter/chargers be at least the same output as 25% of the total battery storage capacity.

Thanks for the info on the 25% ratio, I'm definitely below that at the moment.

But one follow-up question, what role does the converter play while boondocking? If I'm not connected to shore power, is it even doing anything?

 

[jlankford]

I think an important point of the OP is being ignored here. They mostly dry camp and rarely use shore power, so they rarely use the converter, and therefore will rarely use the 5A charger. So why waste money replacing the converter that is hardly ever needed? I think their plan makes sense, with a few caveats.
I carry a separate AC-DC charger, and if my converter ever dies I will do exactly what is proposed here -I won't waste money replacing the converter and will simply use the charger when we have hookups. In my case the charger does a better job than the converter anyway.

Some caveats:
My AC-DC charger is a 20A model. I don't know your 12V load requirements. Only you can do the math to decide if a 5A charger is going to keep up with your load requirements.
If you dry camp with a generator then your converter is being used more than you've stated, and the 5A charger may not be a suitable replacement.
If during the few times you use shore power you expect to recover a depleted battery overnight, you'll probably need a bigger charger (e.g. you've been dry camping in bad weather and the solar hasn't kept up, so you figure one night with full hookups will get you going again).
If you have a 12V only fridge the 5A charger isn't going to keep up with your 12V loads while on shore power.
I presume your NOCO charger is a Li capable model. If not, your converter might be keeping your Li battery better conditioned / balanced. I'm unaware of any other reason you need the converter. And your solar is presumably Li capable anyway, so this is a moot point.

I don't know where that 25% ratio rule comes from, but I'm nowhere near it. My converter is rated for 35A, so I'm at 11%. And actually, I never see more than 22A of charging current from the converter (usually it's closer to 10A), so the real ratio is 3 ~ 7%. And we're fine.

 

[TacomaJoe]

Thanks for the info on the 25% ratio, I'm definitely below that at the moment.

But one follow-up question, what role does the converter play while boondocking? If I'm not connected to shore power, is it even doing anything?

While boondocking the converter does nothing. When you have shore power or generator, the converter takes that 120VAC and makes 12VDC to power your fans and lights, and charge your battery. The converter at 55A will charge the battery 10 times faster than the NOCO.

 

[D W]

... and don't forget, the onboard battery also powers your emergency break-away trailer brakes, so you'll want to keep that battery charged. I'd replace the converter myself.

 

[Larry-NC]

I respectfully disagree...

I think an important point of the OP is being ignored here. They mostly dry camp and rarely use shore power, so they rarely use the converter, and therefore will rarely use the 5A charger. So why waste money replacing the converter that is hardly ever needed? I think their plan makes sense, with a few caveats.

I respectfully disagree.

I learned the hard way that there is a difference between battery chargers and RV converters, while taking several weeks to find and fix a significant parasitic drain (120 mA) on our 2015 GMC Sierra 2500HD.

The difference is that, unlike converters, battery chargers (two or three different ones I tried) charge a battery and shut off. They don't start recharging, regardless of the drain and state of the battery. Ruined a battery that way. Converters continually check battery state and increase charging voltage as necessary.

 

[jlankford]

I respectfully disagree.

I learned the hard way that there is a difference between battery chargers and RV converters, while taking several weeks to find and fix a significant parasitic drain (120 mA) on our 2015 GMC Sierra 2500HD.

The difference is that, unlike converters, battery chargers (two or three different ones I tried) charge a battery and shut off. They don't start recharging, regardless of the drain and state of the battery. Ruined a battery that way. Converters continually check battery state and increase charging voltage as necessary.

Well, that's an excellent point. Now you've caused me to need to test my Li charger's behavior. I know most (all?) chargers will enter a trickle / maintain mode once a battery is full, but that's no assurance it will source enough current if loads later increase.

 

[AudiDudi]

<snip> I know most (all?) chargers will enter a trickle / maintain mode once a battery is full, but that's no assurance it will source enough current if loads later increase.

My standalone charger (2/10/25 amp with repair mode) shuts off when it is done charging. I've never seen one that will restart.

 

[Backcountryboondocker]

I respectfully disagree.

I learned the hard way that there is a difference between battery chargers and RV converters, while taking several weeks to find and fix a significant parasitic drain (120 mA) on our 2015 GMC Sierra 2500HD.

The difference is that, unlike converters, battery chargers (two or three different ones I tried) charge a battery and shut off. They don't start recharging, regardless of the drain and state of the battery. Ruined a battery that way. Converters continually check battery state and increase charging voltage as necessary.

Depends on the charger. I know the NOCO GenPro is a charger AND maintainer, and once the battery is fully charged it stops charging until it hits a certain level and then starts charging automatically again.

 

[Backcountryboondocker]

My standalone charger (2/10/25 amp with repair mode) shuts off when it is done charging. I've never seen one that will restart.

https://no.co/genpro10x1

The NOCO GenPro’s automatically restart charging once the battery level hits a certain point.

 

[Backcountryboondocker]

Hello, my converter just died and I was wondering if I needed to replace it, or if I could just hook up my NOCO 5AH battery charger and it would do the same thing. I just did this on my last camping trip where I used an extension cord to plug in my battery charger the whole time while my battery ran all the 12v systems. I was wondering if there is a long term issue doing this, and/or if the converter does other things I'm not aware of that I need. I generally dry camp, so connecting to shore power only happens once or twice a year, so I'm considering not replacing the converter. Thanks!

Using the NOCO to charge the battery while hooked up to power is perfectly fine if you don’t use a lot of battery power to begin with. (Propane fridge, minimal lights usage, etc…) And if you have the solar panel connected while also using the charger than you should be putting in enough power to keep it up. When my trailer is sitting there at the house I have a NOCO 10 plugged into it to keep it charged and maintained instead of using the converter.

 

[MR.M]

Hello, my converter just died and I was wondering if I needed to replace it, or if I could just hook up my NOCO 5AH battery charger and it would do the same thing. I just did this on my last camping trip where I used an extension cord to plug in my battery charger the whole time while my battery ran all the 12v systems. I was wondering if there is a long term issue doing this, and/or if the converter does other things I'm not aware of that I need. I generally dry camp, so connecting to shore power only happens once or twice a year, so I'm considering not replacing the converter. Thanks!

It will work but 5 amp is to small . for the price of a converter i would just replace the converter . most can be had for $150 or less and be lithium capable . even when boodocking if you run out of battery and have a generator the converter will charge the battery faster .

 

[Aussieguy]

Upgrade the Solar if you going to spend any money
And / or …… another 100ah battery
Have now camped from Florida to Ohio and have had no issues with keeping battery charged each day


I have turned OFF my converter even while connected to 120v
Saves power while mooch docking on limited amps

 

[jlankford]

I respectfully disagree.

I learned the hard way that there is a difference between battery chargers and RV converters, while taking several weeks to find and fix a significant parasitic drain (120 mA) on our 2015 GMC Sierra 2500HD.

The difference is that, unlike converters, battery chargers (two or three different ones I tried) charge a battery and shut off. They don't start recharging, regardless of the drain and state of the battery. Ruined a battery that way. Converters continually check battery state and increase charging voltage as necessary.

Well, that's an excellent point. Now you've caused me to need to test my Li charger's behavior. I know most (all?) chargers will enter a trickle / maintain mode once a battery is full, but that's no assurance it will source enough current if loads later increase.

Unfortunately my test has proved out Larry-NC's point. My Li charger runs a one-and-done charging profile. It was a bad assumption to think the thing would stay in a maintain mode - it doesn't even output 0.25A once charging is complete. I'm a little surprised. All the FLA car chargers I've ever used stay in an indefinite maintenance/trickle mode.

I hereby retract all my statements above. If my converter ever dies, I will plan to replace it.

My test started with discharging batteries to about 80%, then starting the charger. At first I thought this was going to work - when the batteries reached full and there was zero current flowing on the shunt the charger kept running. But that was because my fridge compressor was running and pulling ~4A. After the fridge cycled the charger indicated "charge complete" and at that point my base current (parasitic current) of 0.26A started coming from the battery - zero being supplied by the charger.
I let the battery discharge down to 20% and 12.9VDC to see if the charger would reach a trigger threshold and resume a new charge profile, but it never did.

 

[jcarenz]

Replace the converter

Definitely replace the converter. You can replace the converter for the same cost as a decent battery charger. The converter is more than a charger, hence the term. "converter". Converting 110VAC to 12VDC is crucial if you are on any type of external shore power, including on generator or at home.

Could you get by, probably... but why would you want to? The cost of a few hundred $ to replace the converter will contribute a lot to the value of the RV / TT / 5'er that is worth several thousand $, compared to the value of an RV that has a non-working converter. Think a bit about resale or trade value of your RV. just my $.02.