Battery Charging Rate

[huntindog]

I think that would be fine if your were boondocking, but the OP did state the park he wants to stay in allows limited daytime use of the generator.

Well then that really eliminates a lot of options.

Probably be best to make sure he has a site with electricity.

[CoChris]

We have a 2017 Imagine 2950RL. The GD parts-locator says our converter/charger has a 55 amp output. Does anyone know how much of that goes to recharging the battery (or where I can find out)?

In Nov, we will be dry camping for a few nights (first time, and in the cold) in a park allowing limited daytime generator use. I am concerned about the time to recharge our battery after nights of furnace use (Suburban claims 9.4 amps!) - we'd really like to get out and enjoy the park instead of sitting next to a noisy generator all day ...

Thanks,
Mark

A simplistic answer to your original question is the converter/charger will provide power to all of the 12V DC appliances in the trailer. After that load is satisfied, whatever capacity is left over (out of the 55 amps) is available to the battery for charging. If the battery is low, it may take all of the available remaining current. If it is fairly full, it may take only a little of the available current. The converter charger is capable of UP TO 55 amp output. It will only output what is needed, up to 55 amps. There is a lot of discussion about how good of a battery charger the WFCO units are, but that is a different discussion.

Chris

[SolarPoweredRV]

We have a 2017 Imagine 2950RL. The GD parts-locator says our converter/charger has a 55 amp output. Does anyone know how much of that goes to recharging the battery (or where I can find out)?

In Nov, we will be dry camping for a few nights (first time, and in the cold) in a park allowing limited daytime generator use. I am concerned about the time to recharge our battery after nights of furnace use (Suburban claims 9.4 amps!) - we'd really like to get out and enjoy the park instead of sitting next to a noisy generator all day ...

Thanks,
Mark

My main concern with your plan is that you may not have enough battery for your actual needs. RV furnaces are notoriously heavy consumers of electrons, I call them energy pigs.

You need to know exactly how many amp hours you have in your battery before you attempt to boondock in conditions that may require use of the RV furnace. Unless you have replaced the battery that your dealer installed, you may have less than 75ah (ah = Amp Hours) available in your battery. Combine this with the 50% discharge limitations of Lead Acid batteries and you have 37.5ah available to run your lights, water pump and 9.4 amp furnace.

On a previous coach I tested my 100ah, Deep Cycle Marine/RV battery and determined I could run my coach overnight using the furnace. One thing to note is that this test was performed using a fully charged battery and I did not run the test a second night ( I also was in a campsite with electric hookups so if the battery gave out in the middle of the night, I could simply turn on the breaker for the Converter). With your limited generator hours you are going to have a very hard time getting your Lead Acid battery back to 100% charge after the first night.

I would seriously recommend upgrading to a Lithium battery (LiFePo4) and a separate Lithium charger (I would recommend replacing your OEM Converter, however your time frame is a bit tight for getting it installed) . Of course if your Converter is a newer Converter that is Lithium capable, then you can avoid the separate Lithium charger.

The advantage of converting to Lithium batteries is that you can use 100% of the 100ah rating versus only 50% of the Lead Acid batteries. Additionally, the Lithium batteries can accept charging at a higher rate and much faster than the Lead Acid batteries. Longer life, combined with faster charging will make your boondocking trip with Lithium batteries much more enjoyable.

I would recommend at least one 100ah Lithium battery as a minimum, however, you should strongly consider 200ah of Lithium battery storage for boondocking.

PS: To avoid extra expense, instead of just getting a Lithium charger, you could actually purchase an 80 to 90 amp Progressive Dynamics Converter and connect it directly to your new Lithium battery(ies) for your trip and install it permanently in the coach after the trip.

Good luck on your trip and please let us know how you faired on your boondocking trip.

[rv quilters]

A simplistic answer to your original question is the converter/charger will provide power to all of the 12V DC appliances in the trailer. After that load is satisfied, whatever capacity is left over (out of the 55 amps) is available to the battery for charging. If the battery is low, it may take all of the available remaining current. If it is fairly full, it may take only a little of the available current. The converter charger is capable of UP TO 55 amp output. It will only output what is needed, up to 55 amps. There is a lot of discussion about how good of a battery charger the WFCO units are, but that is a different discussion.

Chris

While there may be a large capacity AVAILABLE to the charger, I'm wondering how to find out the limitations of the charger itself -- at what maximum amperage will it try to charge my battery, so I can estimate the time required?
Other members have posted a range of possibilities from a couple of hours to a full day of generator time.

[rv quilters]

@SolarPoweredRV ,

"My main concern with your plan is that you may not have enough battery for your actual needs. RV furnaces are notoriously heavy consumers of electrons, I call them energy pigs."

Lots of good info in there, and I have similar concerns about making it through the night and getting recharged during generator hours. If we survive and enjoy this part of our trip, I'll be looking seriously at lithium and solar; they would open up so much more of the camping world to us.

[jkwilson]

While there may be a large capacity AVAILABLE to the charger, I'm wondering how to find out the limitations of the charger itself -- at what maximum amperage will it try to charge my battery, so I can estimate the time required?
Other members have posted a range of possibilities from a couple of hours to a full day of generator time.

The battery largely determines how much current flows from the charger to the battery, up to the limit of the charger. A larger output charger only helps during the early stages of charging a heavily discharged battery.

Depending on the weather, you may be deeply discharging your battery running the furnace, and recharging it to state to get you through the next night will likely take 6-8 hours depending on the size of the battery. Conventional lead-acid batteries aren’t very efficient at charging, wasting around 50% of the energy provided to them.

Bottom line is that there are too many unknown variables for any answer to be more than a guess.

The converter won’t be your limiting factor.

My recommendation is to take a lot of blankets so you can deal with things while you figure out what works.

[rv quilters]

@jkwilson ,
This helps a lot. Even with the uncertainties involved, it's good to know that the onboard converter/charger should work as best as the battery can take and that I shouldn't need an external battery charger.
From the combined advice on the list, looks like our plan going in will be to generator-charge most of the day, get the trailer as warm as possible with the electric "fireplace" heater just before quiet hours, and cover up well during the night. Luckily, we are quilters and have a lot to cover up with.

[jmbopp]

@MoonShadow_1911
Thanks. I forgot these don’t always follow in order.

@jmbopp ,
Thanks.
Do you let the generator charge the battery through your trailer system or through an external charger?
Mark

Actually, I have an Iota-55 deck mount converter mounted inside the hookup center in the pass-through. It's a shorter run to the batteries and has a better charging profile for getting a faster charge off a generator. The factory WFCO is still wired in but turned off at its breaker.

[SolarPoweredRV]

@SolarPoweredRV ,

"My main concern with your plan is that you may not have enough battery for your actual needs. RV furnaces are notoriously heavy consumers of electrons, I call them energy pigs."

Lots of good info in there, and I have similar concerns about making it through the night and getting recharged during generator hours. If we survive and enjoy this part of our trip, I'll be looking seriously at lithium and solar; they would open up so much more of the camping world to us.

I just found several LiFePo4 batteries on Amazon below $299 and one as low as $279. Even if you don't upgrade your Converter you could easily install one of these Lithium batteries before the trip which will at least let you charge faster and give you more energy storage even with the OEM Converter.

PS: If you find a battery you are interested in, you can check out YouTube to find out if someone has done a tear-down of the battery to see if they are any good. I recommend videos from both Lithium Solar and Will Prowse, they both perform excellent tear-downs and solid information on Lithium batteries.

[CoChris]

While there may be a large capacity AVAILABLE to the charger, I'm wondering how to find out the limitations of the charger itself -- at what maximum amperage will it try to charge my battery, so I can estimate the time required?
Other members have posted a range of possibilities from a couple of hours to a full day of generator time.

Ther is no "one answer" to your question. It depends on many variables. The main ones are the state of charge of you batteries, battery technology (Flooded lead Acid vs Lithium vs xxx) and how much other load (furnace, fans, lights, radio, etc.) you are drawing off the 12V system at any given time. These will all vary depending on YOUR particular usage, season, weather, etc.

The best way to find out (after the fact) your specific use and charge rate/time is to install a battery monitor (Victron 712 are very well regarded) and see what your exact usage is. That will tell you at any given time what is your battery charge or discharge rate and current State of Charge.

Chris