Separate LiFePO battery

[Urlauber]

Originally Posted by michaelingp

I'm in the same boat. I have solar panels on the van, but no gas-powered generator (and don't see it as a solution anyway). If we stay a couple of nights at a campsite without electricity, we're fine, but over two nights without plug in power is going to drain the batteries too much (we have two small compressor fridges, nothing else uses significant power). So the question is, has anyone else figured an easy way to use one of these "portable power stations" to supplement the house batteries? Has anyone tested using the 120v output of the portable power stations to charge the house batteries? In theory it seems there would be significant loss due to inverter/converter inefficiencies, but some real-life experience would be great to hear, since that would be an easy solution not requiring any wiring changes or access to the house batteries. Also, it would be wonderful to hear experiences with particular brands/models of portable power stations.

Not sure if you had a chance to read any of the preceding posts, but in #16 I explained how I wired the added power station into my campers system.

With a switch, I can either charge the power station from the house batteries (indirectly by the solar panel, generator, hookup, or alternator), or run the camper from the power station. The switch has a middle position where it just disconnects to do neither.

Charging the house batteries via the 120V inverter output of a power station doesn't make sense to me, since you are losing energy (not sure exactly how much) in the back and forth conversion. If your compressor fridges run on 12V you can either hook them up to run off the 12V output of the power station directly, or do what I did and run the entire camper from it, incl fridges lights water pumps etc.

I have not really used the setup that much since it is Winter and everything around here is closed due to some rain. However, I am planning the following:

At night, I will run everything from the power station. During the day, I will switch over to the AGM batteries, and charge the power station via the solar panel (via the regular coach batteries). There will be less energy returned to the power station, but it should last at least 3 nights, depending on what all is running (mostly fridge plus Truma heater and propane solenoid in Winter), and once it is empty I still have the coach batteries to extend things out for another few days, depending on the incoming solar power.

This would be for my usual 3-4 day outings in one spot. For longer trips which involve a lot of driving, I probably don't need to take the power station.

For example, end of May we will be 4 days in Yosemite. There is no hookup, and the camper will be in the shade. With the power station we won't have to run the generator.

There's an interesting idea about

directly connecting

a LiFePO4 battery to your existing AGM batteries... Just stuff to think about.

[michaelingp]

Originally Posted by Urlauber

Not sure if you had a chance to read any of the preceding posts, but in #16 I explained how I wired the added power station into my campers system.

Sorry, I should have read closer and I really appreciate your sharing your experience since it might save me a boatload of $$. Still, my situation is a little different. For one, I don't have a master cut off switch, so no easy way to disconnect the AGM's. I agree that there would be inefficiency in just using the 120V output of the power station to charge the house batteries (while running the 12V system), but for me the simplicity in not having to do the wiring and/or install switches might be well worth it if the hit was, say, 20% or less.

I'm looking into a major conversion of the AGM's to Lithium, and it seems extremely expensive and maybe not all that much better given the disadvantages of Lithiums. It sounds like I should buy the power station and see how it works. Worse that happens I have a power backup for my house if we ever lose power.

[Urlauber]

You don't have a main switch? What do you do if you want to store the camper in a place that does not have light/hookup? Hard to believe.

I have used the Power Station a couple of times for camping and am really happy with it. Less worry about running down the house batteries, and charging it up during the week when I don't use the camper makes good use of the solar energy from the 190W panel.

I am sure you can charge the house batteries with the Power Station, but someone else has to do the math to see if all that inverting and converting makes sense. I wanted to maximize the output I get and it seems to work well.

[hbn7hj]

The archives here are full off people directly connecting lithium and FLA or AGM. You will note they all quit posting. I can, and did, try it just by turning the battery switch to both. Bottom line is if you want full use out of each bank you need to separate them.

It may work for the sailboat guy but not for me.

To me the greatest advantage of the separate systems, since I use a generator, is that I can start the generator without knocking sat TV, Starlink, or DVD player off line. The FLAs stay in the original, non temperature controlled location and the lithiums are happy inside.

[michaelingp]

Originally Posted by Urlauber

You don't have a main switch? What do you do if you want to store the camper in a place that does not have light/hookup? Hard to believe.

I just pull the 3A fuse for the propane/CO detector, since that's all that uses power when we're not camping. And the solar panels keep the AGM's full and happy.

[Urlauber]

Originally Posted by michaelingp

I just pull the 3A fuse for the propane/CO detector, since that's all that uses power when we're not camping. And the solar panels keep the AGM's full and happy.

Interesting, didn't know there were campers without a main switch/battery disconnect. Yeah, I can see how that makes "switching over" to the aux battery a bit more challenging.

[Urlauber]

Originally Posted by hbn7hj

The archives here are full off people directly connecting lithium and FLA or AGM. You will note they all quit posting. I can, and did, try it just by turning the battery switch to both. Bottom line is if you want full use out of each bank you need to separate them.

It may work for the sailboat guy but not for me.

To me the greatest advantage of the separate systems, since I use a generator, is that I can start the generator without knocking sat TV, Starlink, or DVD player off line. The FLAs stay in the original, non temperature controlled location and the lithiums are happy inside.

Yeah, agreed, there is a lot of potential for Kaboom!
In theory, if the voltages are always synchronized, it should work. I guess the dude wants to sell his battery manager thing.

Using a Power Station with its own BMS seems much safer. The one I have maxes out at about 80W charging wattage (it's really made for 18V input), so very safe for everyone incl house batteries and alternator.

Couple of years ago this may have been a tastier option, but nowadays there is a plethora of these ~1280Whr Lithium Power Stations so the prices have plummeted to a level where it almost matches the naked batteries.

[hbn7hj]

Probably the greatest advantage of a dedicated system rather than a power station is charge rate on the lithiums. I’m at 100 amps right now still working toward 200 amps.

We expect to put something together and test it this summer. The goal is to get daily generator runs in the 15-30 minute range. This is for a stationary RV without shore power.

Two of my four Battleborn batteries are six years old and are not charging very well. I will pass through Reno this fall and may ask them to explain to me the reduced charge rate. In the meantime I’m gonna try the 206AH SOK battery. Using a different charger maybe I’ll get closer to 200 amps.

That would be a charging wattage of 2800 watts. (4k generator)

[booster]

Originally Posted by hbn7hj

Probably the greatest advantage of a dedicated system rather than a power station is charge rate on the lithiums. I’m at 100 amps right now still working toward 200 amps.

We expect to put something together and test it this summer. The goal is to get daily generator runs in the 15-30 minute range. This is for a stationary RV without shore power.

Two of my four Battleborn batteries are six years old and are not charging very well. I will pass through Reno this fall and may ask them to explain to me the reduced charge rate. In the meantime I’m gonna try the 206AH SOK battery. Using a different charger maybe I’ll get closer to 200 amps.

That is interesting on the Battleborns possibly not doing well at this point. Battleborn reduced the max charge rate a few years ago IIRC and many of us wondered why and I thought it may have been mostly due to BMS issues, but it may really be a battery damage issue depending how yours turn out


When all this lithium stuff started, they were touting 5C charge rates so 500 amps into a 100ah battery, but most have pulled way back on charge rate recommendations so something must be showing up for the them to do that change.


Early on the lithium systems tended to be quite large, like the ARV ones of the time, so high charging rates per 100ah were essentially impossible due to charging equipment that couldn't supply more then 300 amps continuous. No we see smaller lithium batteries with larger chargers so the charge rate may be starting to actually get tested in the real world, and Battleborn was in early on smaller installs so it makes sense they might see any issues first.

[hbn7hj]

Initially I charged to 14.6 volts. Now it seems prudent to use 14.3 volts. The max charge rate I could get was .3C or 30 amps per battery because the smart chargers interacted and would not put out their rated current.

I have a 100 amp dumb charger ready to go in to replace two 60 amp smart chargers that together put out 80 amps max. If it works I’ll replace the remaining 80 amp smart charger with another 100 amp dumb charger and see what happens.

[Urlauber]

Indeed, the rate of charge is a main difference between regular Lithium batteries and those Power Stations. The PS I purchased maxes out at 180W charge rate, so it would take about 7 hours to completely charge it from empty.

For me, a very slow charging rate works great, since I use the solar panel as the main power source. Fills up the PS over several days to be ready for the next outing.

[michaelingp]

Originally Posted by rvsprinterguy

I've added a port to connect an external power bank to my house battery. It's a fused Anderson Power Pole jack wired directly to the battery under the passenger seat in my Sprinter.

The intent is to have the power bank supply power to the 12-volt system until it's exhausted, at which point the house battery takes over.

So far, it's working as intended, with the major test being a trip to Death Valley and being able to run the refrigerator during nights when we didn't have hookups.

I haven't run the system very low, so I don't know how long it can run, but I'm happy with the results I've seen.

So this would be essentially the configuration described in the boat video (post #21 in this thread). I assume you are using the 12V out ports on the Yeti, which are limited to 15 amps. In addition to supplying power to the 12 volt system, it would seem that the power bank is also (somewhat) charging the house battery, no? If this works, then it seems that Urlauber (or me) doesn't have to worry that the AGM's are disconnected when the power bank is connected. So, the wire from the power bank and the fuse are sized for the 15 amp max from the Yeti? I like this solution, since it does not require much in the way of switches or re-wiring, which are both difficult in my van.

[Urlauber]

Good point. I have not actually tried to see what happens if both the PS and the AGMs feed the beast. Not sure how the PS would react if it receives higher voltage on its "Out" port.

My PS has a USB-C In and Out port, but it is limited to 60W, which I regularly exceed (fridge + lights + propane solenoid + fan), so that one doesn't work well to supply power.

[Urlauber]

To prepare for more drastic changes, I would like to test out running (almost) everything off this 1200Wh power station and see how it goes. Main reason is to see if a 100Ah battery would be sufficient for our needs.

1) I have already wired the PS into the 12V panel via a switch which allows me to connect it when the main switch is off. This way I am running most things off the power station - fridge, lights, Truma, fans, etc. The max it puts out through its 12V port is 120W, which is (obviously) insufficient to start the generator, but also not enough to work the awning. Otherwise everything mentioned above works normally. The house inverter is wired directly into the AGMs, but a) I don't use the inverter and b) the PS also has an inverter built in if I needed it.

2) I added a switch to divert the 190W solar panel output into the Anderson port of the PS, charging it with its maximum input of 120W.

3) This would leave three things that I want to disconnect; a) The Main Switch "off" to interrupt the connection to the 12V panel. b) The Converter - well I don't really have to do anything here, as long as I don't plug in or run the generator it is not being used. Or does it do other things like powering USB ports?? Or how do the 12V turn into 5V USB? And c) the alternator charging via the BIM. Does anyone know if there is a fuse or something to interrupt that? I would like to avoid screwing around with the battery poles.

All of this is just temporary to see if 100Ah is enough to run all stuff when being recharged during the day. The solar panel adds about 50-60 Ah per day which, if my observations are correct, will be enough to account for energy consumption.

Eventually I want to get a "naked" 100Ah LiFePO4 battery and replace the two AGMs as discussed in the thread linked to above.

[hbn7hj]

The generator does not get it’s starting current through the power panel. It is direct from the AGM battery without a circuit breaker. Just an FYI.

[Urlauber]

Originally Posted by hbn7hj

The generator does not get it’s starting current through the power panel. It is direct from the AGM battery without a circuit breaker. Just an FYI.

Yes, that, and the inverter as well.

Thinking about the need to rewire the generator to the chassis battery, as a single 100Ah LFP may not have enough ooomph to start the Onan. Not sure how that would affect the starting procedure, as well as the AGS system.

So much to learn...

[Urlauber]

The power station I mentioned in the OP has now dropped from 500 (when I bought it) to 360 (after a 200 coupon) which is pretty crazy for a >1200Wh LiFePO4 PS.
Good to see prices drop. Pondering to buy a second one but have absolutely no reason for it.

[michaelingp]

Originally Posted by @Michael

Take a power station along. When your AGM needs a recharge, plug the camper into the power station with an extension cord and recharge the camper. You probably could get another day or two off grid that way.

Any reason that would not work?

Getting the power station recharged while on the road might be a hassle.

I tried this with great expectations. I bought a pecron E2000 LFP power station rated for 2,000 watts on its 120V outlets. I know from testing that my van charger only draws about 500 watts for its Tripp Lite RV1512UL charger, so it seemed like it would work fine. To my dismay, it didn't work. The power station output when I plugged the van into it fluctuated wildly and never got near 500 watts. The instability worried me, so I halted my testing, but clearly it was going to take forever to charge the house batteries from the pecron. I contacted pecron support, and their response was that the Tripp Lite was essentially an inductive load, meaning that when it "started up" it exceeded the 2000 watt capacity of the pecron. (The charger acts, apparently, the same as, say, an A/C compressor, drawing a huge load at start up). They implied that the instability I was seeing was some protective circuitry cutting in and out.

Has anybody else tried this solution, with maybe a different brand power station? Would anybody with a power station be willing to try it in the interest of science even if they wouldn't actually use it camping?

[rvsprinterguy]

I have found the 10-amp limitation on the Yeti 1000x DC port to be kind of inconvenient. Sometimes, when I connect the battery bank to my AGM house battery, an overload prevention device in the Yeti trips, causing the DC output section LED to turn red and the output switches off. If I make sure everything is off before plugging in the APP cable, the LED remains white, and all is OK. I can then turn on the refrigerator and other things and all is well.

Turns out Goal Zero sells a "12 Volt Max Current Cable" that has plugs to tap all four 12-volt outputs to provide up to 40-amps. Their website says it's out of stock, but it looks pretty easy to build. Hmmm. Their website also says not to use it with Yeti X Power Stations, which is what I have. I wonder why this is so.

[Urlauber]

Originally Posted by michaelingp

I tried this with great expectations. I bought a pecron E2000 LFP power station rated for 2,000 watts on its 120V outlets. I know from testing that my van charger only draws about 500 watts for its Tripp Lite RV1512UL charger, so it seemed like it would work fine. To my dismay, it didn't work. The power station output when I plugged the van into it fluctuated wildly and never got near 500 watts. [...]
Has anybody else tried this solution, with maybe a different brand power station? Would anybody with a power station be willing to try it in the interest of science even if they wouldn't actually use it camping?

So you are trying to charge the camper house batteries from the power station 110v output? I haven't tried that, I am running the camper 12v accessories directly from the 12v outputs of the PS.