Recharge Litium Power Station with RV Alternator?

[Chronic]

I bought a Big Blue CellPowa 2500 portable power station a year or so ago to use on a different project, but would like to use it in my Class C 2004 Winnie 324v as a supplemental power source. The power station has plenty of juice to run the microwave for a quick frozen meal or to heat up a cup of coffee, and it avoids firing up the on-board Onan generator. It would easily run the electric/gas refrigerator, if I could only recharge it while I am on the road. I tried plugging it into the 12v cigarette lighter, but have been able to recharge only plus/minus 30%, even with 10 hour driving days.

YouTube has many videos of people wanting to do the same thing, that is, recharge lithium batteries or power packs from their RV alternator. Different alternatives include DC to DC chargers, DC step-up converters, and 12v to 110v inverters. The trouble is that I am lazy and don’t want to have to string heavy-gauge wire through a maze of holes and channels. Thus, I first tried a plug-in 300w 12v to 110v pure sine wave inverter.

Unfortunately, although the Kill A Watt monitor plugged into the inverter showed the full 110v, there was no amperage output. My knowledge of electric function is near zero, but it seems to me that if there is voltage, there should also be amperage. Yet both the Kill A Watt monitor and my power station showed no amperage output.

So I am left with one of the two other alternatives: DC to DC charger or DC converter, both requiring stringing wires. I am hoping someone on this forum has been through the same process and came up with a simple and elegant solution; something that will work with an innately lazy person. If I have no other choice I will do what I have to do, but I am hoping one of you has a solution.

Thanks for your help, Ron

[creativepart]

The DC2DC charger is probably your only option. I don't know where you plan to place the CellPowa 2500 but you don't need big wires run every which way.

Since you have a Class C RV I would assume you have both a house battery and a chassis battery both under your stairs in the stairwell. Though since you have a 300 series Class C it's possible that the House battery is under the stairs and the chassis battery is under the hood.

Either way, let's say you get a Victron Orion 30-amp DC2DC charger you just need a minimum 10 gauge wiring from your battery bank to the DC2DC charger and the same to the 12v charging port on your CellPowa 2500. 10ga wire handles up to 30amps and since the Orion 30-amp only draws that much that's all you'd need.

Since your Alternator charges both your house and chassis batteries while you drive, if you connect the DC2DC charger to one of those batteries you will be connected to the charge current coming from your Alternator.

I don't know your RV's layout. But perhaps you can store the CellPowa 2500 in a basement compartment near your door. Then install the DC2DC charger in that same compartment or under the stairs with your battery and then just run one pair of 10ga wiring from the charger to your CellPowa 2500.

Only you can know the logistics.

I have this Victron DC2DC charger in my Class A, I use it to directly charge my Lithium batteries. I run a 10ga wire from my chassis battery in the stairwell to under the coach and across to the other side of the coach. So, the wire is probably 10' at most to the Victron charger that I've placed in a compartment with my 400-amp hours of LFP batteries.

This was a simple install for me and my layout. Took less than 3 hours start to finish. And, it charges my batteries very well.

The Victron has one great feature others do not - it is automatic starting and stopping. When it senses charging from the alternator it turns on and when you turn off the vehicle it turns off. Other brands of chargers require you to run additional sensor wiring to your battery combiner solenoid to turn the charger on when you start the engine and off when you stop.

Only you can figure out how to make a practical installation of the charger and the CellPowa 2500.

One other thing, if you plan to plug your RV into the CellPowa 2500 via your RV's 30-amp shore power cord, be aware that your OEM converter charger will see the 110v and think you are on shore power and try to charge your house batteries. You don't want that. You would have to throw the circuit breaker to the Converter and then remember to turn it back on when on shore power.

That's something people with these "solar generators" tend to forget. Using one of these to charge other batteries is really, really inefficient. And plugging in like shore power would automatically power your built in battery charger.

[Chronic]

Thank you for your response. My Class C does have the chassis battery under the hood, and while I suppose I could tie a DC to DC charger into the house batteries for a shorter wiring run, if I go the DC to DC charger route, I will run the wires from the chassis battery; the same for a DC converter.

I am still hoping an electrical engineer or similarly experienced person will take pity on me and tell me why my trial using the 12v to 110v 300w inverter didn’t output amperage. It doesn’t make any sense to me, although as I said earlier, my knowledge of electrical function is sadly lacking.

I intended to put in a solar system originally, but when we travel in the camper, we are usually on the move, rarely spending more than a night or two in one place. 10 hour travel days are common. If I can use extra alternator output, solar panels won’t be needed.

Again, I appreciate your help. Your system sounds about as simple as it gets, and I may end up there, but I am still hoping for a “plug n play” solution.

Ron

[Morich]

I can't say about the amps /voltage question but there may be an easy way to say why you get so little charge when pluggin into a cigarette lighter, etc.
The charge to the power station will not able to go higher than the power at the plug. That is often very limited due tot he way the plugs are made and the very small wiring and fuse to the plug. Many are not more than 5 amps, so when using that to charge, you will not get more than that 5 amps and that takes a long time.

One of the nice things about lithium batteries is also one of the complications! They can be charged really fast and take in a really large amount (amps) of power. That is nice and quick but it is also the problem as when we might want to connect it straight to the engine alternator, it may use so much power that it overheats the alternator to burn it out!

[powercat_ras]

I looked at the specs of the CellPowa unit you posted about ...

The CellPowa power station has 1,800 watt-hours of lithium battery storage inside.

Based on the specs I don't think the solar input fed by the DC-DC charger or using the 12 VDC charge inputs is going to work for you, too slow of a charge rate either way, the DC-DC is about as slow because it the highest output voltage it can be set to is only about 15 volts.

I think you might want to recharge with it's AC input using a 1,000 watt pure sine wave inverter tied to your chassis DC system.... You'll want to use your phone app to change the AC charging to 400 watts input from the default of 1200 watts. 1200 will be too much load for a Class C alternator to handle.

Renogy 1000 W Pure Sine Wave Inverter

The CellPowa can be set to draw one of 3 power levels from the AC input when charging: 400, 800, or 1200 watts with the cell phone app. I think I'd set your CellPowa to the setting where it draws 400 watts for recharging. This would give you a recharge rate of about 20% per hour. This would add about a 50 amp more load on the alternator over the existing load.

You said you have a class C so I think the 800 watt setting which would draw about an additional 100 amps from the alternator, over the existing load, might be too much load on the alternator, but if it is a Ford E450 chassis Class C you can chack your specs and if it has the heavy duty alternator, if so the 800 watt setting might work and be able to charge twice as fast, 40% per hour.

I would connect the DC input of the inverter to the chassis battery and not directly to the alternator. You should put a 100 amp ANL fuse in the B+ line for protection of the chassis system and for fire saftey. The Renogy inverter I posted a link to has a wired ON/OFF switch so you can shut it off when not in use, to stop it from being a vampire drain on the chassis battery when parked. I'd use 0 gauge wire runs from the chassis battery B+ and B- to the 1000 watt inverter. I'd place the inverter under one of the front seats in the cab and if you position it right you'll just be able to plug the CellPowa right into the receptacle on the inverter to charge it when driving.

[Chronic]

Randy, thanks for your reply. My 2004 Minnie 324v Class C is based on the 2003 Ford V10 E350 Super Duty chassis. I have not found a definitive answer to the question of my alternator output—the best info I have seen says probably 130 amps. I came to the same conclusion that charging the power station would go faster using AC, which is why I tried the 300w inverter plugged into cigarette lighter; however, as I noted, the Kill A Watt monitor showed no amperage at the inverter output. I am still scratching my head on that puzzle. Any idea why no amps? I would think I should have gotten at least a minimal output.

I appreciate your suggestion to use a 1000w inverter and turn the power station input down to 400w. I didn’t know I could do that. I will see if I can figure out how reset the input to 400w tomorrow morning when I am in the camper. The thought of running 0 gauge wire from the battery to the interior of the cab gives me the heebee jeebees, but if I have to do it, I am sure I can do it. I am a bit concerned about overloading the alternator, if I draw off 50 amps for the power station. As I said earlier, I am always a little over my head dealing with electrical stuff. I understand just enough to get experimental, which can mean trouble.

Again, I appreciate your suggestions. I am still hoping there is a simple “plug n play” solution, but the more I research, the less likely it appears.

Ron

[powercat_ras]

The 300 watt inverter probally is going into overload shutdown as the lowest you can set your power station for AC charging is 400 watts.

You should confirm you still have DC on the accesspry outlet, it is probally on a 15 amp fused DC circuit and inverter driving an AC load over about 150-200 watts is going to blow that DC fuse fairly quickly if not instantly.

Your power station probally will charge just fine with a modified sine wave inverter and if you want to experiment you can buy a 500 watt MSW inverter for as little as $ 28. Anytime you are going to drive an AC load over 300 watts you'll have to clip right to the battery posts as the accessory outlets will only be fused for 15 Amps DC and 400 watt load will require well over that.

[Chronic]

Randy, thanks for your response. You are right; the accessory plug is dead, although it must have lasted a bit because I had 110v AC measured with the Kill A Watt monitor. Voltage without measurable amperage doesn’t make sense to me. But then, what do I know. I tried getting into the cab fuse box to change out the 20 amp fuse, but this big, old, stiff body could not contort to get in there. I did manage to get stuck under the steering wheel and between the seat and doghouse; I am glad no one else was there to see the show! I will put that task off until I can get a flexible volunteer to do it for me.

I probably will get a pure sine wave inverter, just because it offers other potential uses. Your explanation of my situation and possible solutions is making sense to me, so I am going to follow your recommendations. I may drop below the 1000w inverter, but will wire in directly to the battery, properly fused, and reset the power station to 400w. What I really want is to recharge the power station while I am on the road, hopefully enough to run the refrigerator and occasionally the microwave. The dual house batteries should take care of the rest of our needs.

Do you have any thoughts about the adequacy of the 130A alternator, whether there is likely to be a problem drawing off enough power to recharge the power station? I suspect the draw from running the vehicle and lights is barely touching the alternator capacity. As I said earlier, I know just enough to get in trouble. Thanks again for your help.

Ron

[powercat_ras]

If you plug your refrigerator into your Kill-A-Watt and put it in AC mode, you'll see it drawing either 300 watts or 600 watts depending on if it is a 2 door or 4 door unit.

If it is a 2 door and using 300 watts AC when the fridge is running , which is about on average about 50% of the time in hot weather if you don't open the doors much, you could use the same inverter to power the refrigerator when driving. That said this type of fridge uses very little propane and it may not be worth the trouble.

[Chronic]

I am back for a “Rest of the Story” report regarding charging my power station using my RV alternator. I enlisted my son to give me a hand for a day, and followed Randy’s recommendations (powercat_ras), with a couple changes. We ran almost 15 feet of 4 AWG wire (Renogy’s recommendation for their 1000W inverter) from the chassis battery contacts, under the cab, up through a handy grommet under the passenger door step plate, and to the inverter mounted under the passenger seat. The wiring run was relatively simple, and close to invisible. We installed both an inline 100 amp circuit breaker and a one-way 100 amp diode in the positive wire—maybe a little overkill with the diode, but trying to protect the charging circuit.

Since the 1000W inverter could draw as much as 83 amps from the charging circuit, and to the best of my knowledge the stock alternator provides 130 amps, we replaced the alternator with an aftermarket 200 amp alternator. I have seen estimates of 30-40 amps for normal vehicle use, and when I factored in the additional 83 amps for the inverter, and the draw for the house battery charging circuit, I decided to spend the extra dollars and boost the available amperage. I figured it is better to have more than we need than to overload the stock alternator and cause an alternator failure in some remote location.

Following Randy’s recommendation, I reset my Cellpowa power station to 400W input, and find the inverter can provide a full recharge from empty within 6 hours. I might set it at 800W when I am on the road and recharge with 3 hours. This is exciting stuff!

The total spent for the inverter Randy recommended (Renogy 1000W), the wire, copper cable lugs, breaker and diode, and the new alternator and serpentine belt was right at $500. I would have spent that much or more for solar panels and associated supplies, and since we drive long distances, and spend short times in any one location, the inverter charging should work better for us, and should provide all the power we need.

Thank you to everyone who helped me think through this project. The Bible says there is wisdom in the counsel of many, and in this case, that is a fact.

Ron

[powercat_ras]

Great job!

The diode is not providing a benefit. It may be becoming very hot when using the inverter. So I'd lose it, or at least make sure if it is dissapating 25-50 watts as heat it's not going to damage anything, depending on how it is mounted and ventilated it may reach a temperature well above 150 degrees F. It could get even hotter than that if not mounted on a metal heat sink, it won't get hot enough to start a fire the diode will burn out before that, but it could get hot enough to melt plastic and or give a nasty burn.

A heads up on the 100 amp DC circuit breaker. If it is a inexpensive one you will find that it will trip with continuous current thru it well below 100 amps, generally unless I really need the ON-OFF toggle feature of the circuit breaker I have stopped using them and now use ANL fuses instead.

[Chronic]

Thanks, Randy, for your reply and recommendations. As I said earlier, I know just enough to get into trouble; it looks like the breaker and diode installation may be an example of that. Since everything is such a clean install, and the wires have already been cut to fit, I am hesitant to pull the breaker and diode and restring a positive line. I think I will run it awhile and see what results. I have an infrared thermometer, so will check everything after a day of driving and see what I have. Best wishes, and thanks to everyone for their suggestions. Ron

[Morich]

Not to say your plan is not good but just to add some ideas for thought if you want to use them?
A heat sink can sound like a big complex thing but when we get down to it, we might call them a heat dispersal unit!
A heat sink on computer stuff is often a chunk of metal that heats and cools pretty quick like aluminum. But if we just want to move some heat from the diode to the air around it, one way to get by on the cheap is to fold up some aluminum. Like metal guttering, soda cans, or whatever we have and feel is good to soak up heat from the diode and spread it around where it then moves out into the air! It is the amount of area that is exposed to the air. Instead of the little surface of the diode, we have the big surface of the metal?

Fold up a piece of flashing (?), mount it on the surface of the RV with a insulation item of some type and then mount the diode on the flashing?
If appearance is not a big thing, a soda can makes a really handy and easy thing to cut and fold! In the field, we never have to look far to find a can that works!
A nice shiny aluminum angle is nice but it might be 40 miles to town to get it, so the can works!

[l1v3fr33ord1]

Chronic-

I realize your project is complete; the information below is for anyone who comes upon this thread later.

I bought a Bluetti EB70 to power the residential refrigerator while underway. Bluetti said it could be charged and discharged at the same time; I found this correct.

It happened there was an "extra" 12V/10A circuit under the cabinetry, so I made a matching connector and charged the EB70 from the alternator. It put in about 60 percent of what the reefer drew. Shore power filled the rest (each evening).

The EB70 allowed charge voltages of 28A or so. I tried putting a 24V converter on the 12V line, but that blew the fuse, so I stuck with 12V.

[Marine359]

Glad you found a solution.
For others who might want to charge a powerstation from alternator, there are now two products designed for that purpose. Powerstations, when charged through their solar port want high voltage and relatively low amperage ( up to 15 amps). The new chargers from Ecoflow and Pecron are designed to do just that. I purchased the Pecron charger. It can deliver up to 500w of charging power to my powerstation, and it cost just $150. It’s programmable, so you can set the starting voltage based on the alternator/battery setup in your vehicle. It comes with everything, including a loom protected wiring harness and inline fuse. If your powerstation is more than 15ft from your engine bay, you may need a xt90 extension cable. The output side terminates with mc4 connectors, so you’ll need a dongle that fits your powerstation’s solar input port. Before installing, make sure your alternator can handle an additional load of up to 40 amps.

https://www.pecron.com/products/pecr...for-car-rv-van

[Chronic]

Thanks for the latest replies to my post. I hope I am done fiddling with this particular issue. I am very satisfied with the installation of the inverter--it is giving me everything I need to fully charge the power station in an easy day of driving, plus there is extra power available, if I need it.


Richard, I followed your recommendation, and improved the diode installation for better heat dissipation, mounting directly onto the steel door frame. Fortunately I had enough wire to re-position it without trouble.


Mark, I tried charging the power station from the 12V accessory plug in the beginning, and was only able to charge up 40-50%, even after a 10 hour driving day. With the inverter I can fully charge within 3-6 hours, depending whether I am charging at 400 or 800W.


Jim, it looks like the Pecron device is the plug & play solution I was looking for initially. Now that the inverter is in and working, I am happy with the result. For now at least, I will run it and see how it goes.


Now, I have a new problem to deal with: my power steering pump started leaking fluid. Because the engine sprayed leaking fluid everywhere, it was difficult to find the source of the leak. YouTube and Ford forums have been a Godsend. I started with the most common failure spot and replaced the teflon seal on the pressure hose, a miserable job. That didn't do it, so the chase began. After several days of crawling under the the engine, cleaning up fluid and inspecting suspects, I think we finally found the culprit. We will replace the pump this week, and hope for the best. I can tell you for sure that these old bones don't like crawling around on asphalt. In the meantime, there will be no traveling to test out the new energy supply system.


Thanks, everyone, for your comments and help.


Ron