Best off grid charging method?

[Frost]

We have a 2024 19' Bambi, not quite a year old. I added 2, 100 ah LiTime batteries and a DC to DC connector shortly after purchase. I know I've more to add and have been reading here a bit.

Just returned from 5 nights boondocking, was a learning experience. Was in complete shade and clouds as is often the case here in northern NY. Without getting into solar and loads on batteries, I'm curious why my generator takes so long to charge. I have a Honda 2000i generator and was disappointed in how long it would take to bring batteries back up to decent soc. Yes, I'm now one of "those guys" that runs a generator.

It seems the generator will need 2 hrs or more to get batteries form 65% soc to 85% or so. The thought of letting things get below 50% and having to run gen for 4 hrs is painful. Looking to improve on that as even a quiet Honda is too loud for me. Was thinking that maybe I should just use my lithium charger plugged into generator and direct to batteries. Maybe there are other solutions.

Any thoughts?

[BGClassic]

After much boondocking, and a trip to Alaska and back, I'd say the best and most economical charging method is by generator. I have the stock 270W of solar, and a portable panel. But, solar only works when it's sunny, and the stock panels are probably not the most efficient. Also, a portable panel needs to be moved to get the most solar energy.

Your charging depends on the converter's DC charging output current. I upgraded to a Multiplus II, and it will output well over 100A into my 400Ah lithium battery bank.

I don't know what your Bambi has for a converter. I do carry a small Victron battery charger, as a backup. I have not even installed a DC-DC charger, as the generator costs less, and I already have it, and it goes on all trips.

[vanderwielen]

Originally Posted by Frost

We have a 2024 19' Bambi, not quite a year old. I added 2, 100 ah LiTime batteries and a DC to DC connector shortly after purchase. I know I've more to add and have been reading here a bit.

Just returned from 5 nights boondocking, was a learning experience. Was in complete shade and clouds as is often the case here in northern NY. Without getting into solar and loads on batteries, I'm curious why my generator takes so long to charge. I have a Honda 2000i generator and was disappointed in how long it would take to bring batteries back up to decent soc. Yes, I'm now one of "those guys" that runs a generator.

It seems the generator will need 2 hrs or more to get batteries form 65% soc to 85% or so. The thought of letting things get below 50% and having to run gen for 4 hrs is painful. Looking to improve on that as even a quiet Honda is too loud for me. Was thinking that maybe I should just use my lithium charger plugged into generator and direct to batteries. Maybe there are other solutions.

Any thoughts?

Install a Victron Current shunt. Additionally, charging is limited by your converter/charger not by the size of your generator.

[LNBright]

So, (assuming an Orion DC-toDC charger), that will help charge the batters while you're towing, but, what else is stock in your system, what else is changed? Do you have a shunt?

If your system's stock charger is still what you're using, it's not quite as efficient as a Victron charger would be; just to double-check, your stock unit is lithium-compatible? Did you need other move the jumper to make it lithium-compatible? The auto-detect for lithium is known to be wonky, it may be trying to apply a lead-acid charge profile to your lithiums. Yes, you could bypass your camper's stock charger and use your lithium charger from the generator, if that's convenient enough (we moved our batteries inside, so that wouldn't be as practical for us, but if you're using the factory battery box, maybe that's easy enough for you). Your Honda should be capable of getting your batteries charged back up much faster than what you're seeing: it really does sound like your charger isn't thinking it's charging lithiums.

FWIW, I swapped out our 1000w inverter for a Victron 3kw charger/inverter, inverted the whole camper: the Victron is much better charger than the factory one, I just turned the factory one off at the breaker, let the Multiplus handle it all now. (You would want two more batteries to be optimal, the Multiplus prefers having 400ah at a minimum, if possible.).

Good luck sorting it out....

[uncle_bob]

Hi

Ok let's do the math:

200AH of battery

65% to 85% is 40AH

If you have the stock converter / charger it may well be putting 20A into the batteries. A lot of folks see this sort of charge level.

2 hours times 20A = 40AH.

So, the math works out.

What to do?

The "easy answer" is to swap the existing inverter for a hybrid inverter / charger. Then set it up to charge at 40 to 80A. Your 2 hours just went to 30 minutes to an hour.

At an 80A charge, your generator will be putting about 10A into the system at 120V. That's a bit over half the output your generator is capable of.

For a full top off of the batteries, you probably should add another half hour of run time. That will allow things to properly equalize. Your example of 50% to full would still take over an hour with an 80A setup or close to 3 hours with a 40A.

Bob

[Frost]

So, I have a WFCO converter that is supposed to auto detect for battery type. Just removed the panel and saw blue light is on.
I'm a little dense about this stuff. Just occurred to me that a generator/inverter supplies AC power through umbilical. Maybe as a test while at home I should run batteries down a bit and see how long it takes for house power to bring them back .
It's a 20 amp receptacle,should be close in output to Honda 2000i generator.
Thanks for help.

[jeffb831]

AC Power is AC Power to the trailer. It doesn't matter if it's plugged into a "wall" outlet or a generator outlet. The path is still the same, it flows through the same 120V inlet on the side of the trailer which then flows through the converter and then onto the batteries

[Frost]

Bob,
Your reply makes real sense to me, thanks.

For now,I'll try generator direct to battery charger to batteries to see if it's any faster. Not too happy about prospect of new converter on new trailer but oh well.

We're not energy users, only 12 volt fridge on low. Nothing else and even that will stop while off grid,it becomes an icebox. Have a little power station for coffee and phone charging.
Can you recommend another converter?
Thanks again

[JeffKim]

Originally Posted by Frost

So, I have a WFCO converter that is supposed to auto detect for battery type. Just removed the panel and saw blue light is on.
I'm a little dense about this stuff. Just occurred to me that a generator/inverter supplies AC power through umbilical. Maybe as a test while at home I should run batteries down a bit and see how long it takes for house power to bring them back .
It's a 20 amp receptacle,should be close in output to Honda 2000i generator.
Thanks for help.

At least you have the coveted blue light. With our 50A WFCO-AD it was a pain to get it to switch to lithium. And when I did get it to work, it would charge at 40A or so for a bit then decline to around 18A. I gave up on it and now I never waste an opportunity to disparage it. I installed a Victron IP43 charger which consistently outputs close to 50A in bulk charging.

I assume you using the Li-Time bluetooth app to determine charging state? With our Victron shunt I can see what the charging amps are. I'd guess the Li-Time app will tell you that as well. If I'm correct, the Honda 2000 is 2000W, so that is 167A DC at 12V. Your WFCO should not be limited by the current available from the generator. If it's slacking, I'd consider another charger. They are not hard to install.

[Frost]

Thank you Jeff,
I do have the LiTime Bluetooth as well as Victron shunt. Shunt confuses me a bit.

Off track here, but my AC panel has 30 amp main breaker and only 15 amp for converter (says 15 amp converter,internal on label). Is that typical for a converter? 15 for converter and 15 for everything else would make sense though. Asking if a 40-50 amp output,or higher ,converter would work on a 15 amp breaker?
Thanks again, simple stuff for many of you but I'm in the learning stage.

[JeffKim]

Originally Posted by Frost

Thank you Jeff,
I do have the LiTime Bluetooth as well as Victron shunt. Shunt confuses me a bit.

Off track here, but my AC panel has 30 amp main breaker and only 15 amp for converter (says 15 amp converter,internal on label). Is that typical for a converter? 15 for converter and 15 for everything else would make sense though. Asking if a 40-50 amp output,or higher ,converter would work on a 15 amp breaker?
Thanks again, simple stuff for many of you but I'm in the learning stage.

We were all at the learning stage at some point (I still am). So keep those questions coming.

Watts are often used to convert from AC to DC. So it's a 15A AC breaker. That's 15A x 120V=1,800W. Your 50A converter will put out a maximium 50A x 12V or 600W, so plenty of room.

I'd trust the shunt more than the batteries. There are some nuances with getting the state of charge reset settings correct. But I have the automatic reset turned off and will periodically manually recalibrate it to 100% when the batteries are no longer absorbing a charge. Is there anything in particular that is confusing?

[PB_NB]

Originally Posted by Frost

We have a 2024 19' Bambi, not quite a year old. I added 2, 100 ah LiTime batteries and a DC to DC connector shortly after purchase. I know I've more to add and have been reading here a bit.

Just returned from 5 nights boondocking, was a learning experience. Was in complete shade and clouds as is often the case here in northern NY. Without getting into solar and loads on batteries, I'm curious why my generator takes so long to charge. I have a Honda 2000i generator and was disappointed in how long it would take to bring batteries back up to decent soc. Yes, I'm now one of "those guys" that runs a generator.

It seems the generator will need 2 hrs or more to get batteries form 65% soc to 85% or so. The thought of letting things get below 50% and having to run gen for 4 hrs is painful. Looking to improve on that as even a quiet Honda is too loud for me. Was thinking that maybe I should just use my lithium charger plugged into generator and direct to batteries. Maybe there are other solutions.

Any thoughts?

We have been adjusting our power system since we got our Bambi in 2020. Ours was void of anything other than the prewire for the solar roof connector and the hitch solar connector. We had one Lead Acid battery up front,

We spent some time getting used to the trailer and finding out the way we wanted to use it. It seemed that we would encounter more primitive sites than fully serviced sites. We tend to like the more primitive situations so we started off adding to the trailer so that we could stay in these spots.

We added a 250ah Lithium battery and changed the converter to one that would charge Lithiums correctly. Then we added a portable 180W solar panel but it just didn't do much for us. Then a MPPT solar charge controller and the panel started to improve (after deleting the onboard charge controller). Then more solar on the roof. We added panels that would fit around the roof hatches and AC unit. Now we have 360W up-top and the portable 180W which I brought out once during the trip just to see what it added to the charge. We got up to 24amps with this but usually we are sitting at 20 amps give or take with the roof solar panels.

We also added an inverter to power all our 120V outlets for the occasional TV time or microwave use. A shore switch manages the 120V input into the breaker panel.

The good part about the Bambi is that anything factory could be upgraded without too much pain to the pocket book.

We just returned from 4 weeks away and the power system worked and handled all our needs without coming close to struggling. We didn't plug the trailer in once during this trip.

We often saw campers using generators during generator hours. There were times when all we could hear were generators running!

If there are times when the solar couldn't keep up due to clouds, we never experienced that but it could happen. We also have a Honda 2000i but haven't used it with the trailer.

[Frost]

Shunt's just confusing because there's often gibberish that I don't understand. Words you can't make out etc. It does give some readout of my modest solar. Victron app was not friendly to me a yr back and I gave up, should just try again.
You've been very helpful,thanks once more.

[BGClassic]

Originally Posted by Frost

Shunt's just confusing because there's often gibberish that I don't understand. Words you can't make out etc. It does give some readout of my modest solar. Victron app was not friendly to me a yr back and I gave up, should just try again.
You've been very helpful,thanks once more.

Start here. Nate runs a great educational channel. I studied and planned for weeks, and it took me a month to upgrade our electrical system.

Everybody has to start somewhere.

https://www.youtube.com/watch?v=ckSiFNv5UvI

[27ftToaster]

Frost,
Welcome to the world of “Do it yourself and figure it out!” We are all there!

My old WFCO 55 amp AD was only putting out about 18 amps when charging as well. Ended up with a Multiplus 3000, and am extremely happy with it. But that is some major work, perhaps for you in the future. But what I found out when I needed to charge my 4 Lithium batteries to 100% when setting them up was that my WFCO could charge at a full 55-60 amps with a short 2 foot cable! When re-wiring for the Multiplus, I saw how the factory had not only left long excesses of cable rolled up, but I also had multiple connection points with poor (high resistance) connections.

What I would recommend is that you trace the output wires from your WFCO to your batteries. If appropriate, shorten any excess wires and inspect each and every connector and connection. Both positive and negative side. That will improve the charge rate substantially, for no cost. Just some good sweat and perhaps a few cuss words!

[BGClassic]

Great point on the cable length. Sadly, most likely OP will have to use larger gauge copper cables as well.

[PaulBristol]

Originally Posted by Frost

Bob,
Your reply makes real sense to me, thanks.

For now,I'll try generator direct to battery charger to batteries to see if it's any faster. Not too happy about prospect of new converter on new trailer but oh well.

We're not energy users, only 12 volt fridge on low. Nothing else and even that will stop while off grid,it becomes an icebox. Have a little power station for coffee and phone charging.
Can you recommend another converter?
Thanks again

The solution to the problem is to replace the WFCO auto detect converter/charger. Sometimes they work and sometimes they don't. In either case it probably does not have a high output.

It does not matter if the WFCO is plugged directly into a generator or is wired through the house 120 volt system. The WFCO will perform the same.

For generator charging, how long the generator runs is important to owners. The higher the capacity of the charger, the shorter the charging time will be.
The pair of Litime batteries can absorb 100 amps. That is a lot more than the WFCO can deliver.

Alternatives:
All these will reliably charge lithium batteries.
Victron Multiplus II - State of the art, but expensive and complicated. If you are willing to learn it is an excellent choice (120 amps max) It also has a built in inverter. There is a cheaper 100 amp model that does not have an inverter.
Progressive Dynamics - Comes in high capacity models. High capacity models do cost more. 80 amps
https://www.etrailer.com/RV-Power-Co...cs/PD89RR.html
GoPower - similar to PD above. 100 amps
https://www.etrailer.com/RV-Power-Co.../34266912.html

https://www.etrailer.com/s.aspx?qry=converter+charger

100 amps charging will charge the pair of completely discharged Litime batteries in a little more than two hours.

[Frost]

Thanks for responding, makes great sense. I'm on it when time allows.

[Frost]

Thanks for the recommendations,is what I was looking for.

[Forester2]

I had the same problem on my old camper with the then new WFCO AD converter. My solution was same as yours- lithium charger direct to batteries. Problem solved.