Separate LiFePO battery

[Urlauber]

Been intrigued by these Portable Power Stations... prices have been dropping and I finally got me one of them ($500 for 1200Wh seemed fair, but there are many to choose from).

So these are only slightly more expensive than a "naked" Li battery and come with a nice shell and outlets and different ways to charge etc.

I got it mostly to easily keep the fridge, computer, etc running in case of power outages at home.

But, I wonder if anyone has used something like that to extend their Camper battery capacity. One could run the compressor fridge on one of these for a while. Of course, that is what the Coach batteries are for, but for extended dry camping in a shaded place where the solar panel does not keep up with the electricity use it may be nice... of course, driving and generator are other options. This is more of a nice to have than necessity.

Just bouncing around ideas... the next step would be to replace the AGM batteries with one of these.

[@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.

[Urlauber]

Not sure there would be enough juice to charge the camper itself with the 1000W inverter. Maybe.

Basically I'd charge the Power Station via the camper's Solar Panel while the camper is not in use. This should work well in Summer while being parked during the week waiting for the weekend trip.

And then during the trip, I was thinking to use the Power Station to reduce the load on the AGM batteries. The 12V fridge is what mostly comes to mind... since that would be running pretty much all the time. Also I might be able to run the microwave without having to crank up the genny. I don't remember the wattage offhand... I think it was 800W or so.

So more for shorter (2-3 day) trips, not necessarily for the yearly 2+ weeks vacation trip.

[@Michael]

Originally Posted by Urlauber

Not sure there would be enough juice to charge the camper itself with the 1000W inverter. Maybe.

Maybe - depending on the amperage of your converter/charger. Mine was a 55A converter rated at 900w peak, 750w continuous.

Shifting loads around would work too - but might be less convenient to manage. My compressor fridge can run from either 12V or 120V power, with 120V prioritized. So plugging the 120V cord into the portable power would shift the load to the portable power.

[Urlauber]

I don't like all the converting and inverting... seems like it would waste a lot of juice (inverting the 12V from the Power Station to plug in the 110V and then the camper converting it back down to 12V. I'd rather stay at the 12V level if possible. My fridge is just a 12V compressor fridge, so no choice here anyway.

[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.

[Urlauber]

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.

That's a good idea! Thank you for sharing! May be better than just hooking up the fridge as I had intended originally.

I am not clear how I would wire that - my camper has two house batteries, both AGM underneath the camper. Wondering if there is a way to rig it so the power bank can be plugged in while the main switch is off. Could I just plug it into the 12V outlet to supply power to everything? If so, what would happen if I would turn on the main switch while the power bank is plugged in?

I am testing the power station right now... I plugged it into the 12V camper outlet to charge it and it sucked in 22W, meaning it would take about 60 hours to recharge it from the solar panel. That works for me, for example to re-charge it during the week for the weekend trip. One of the reasons I bought that thing was to use the excess capacity of the solar panel while the camper is parked. Plugging it into a USB outlet (just for fun) showed 3W delivered, so that is pointless. Specs say it takes 65W but I guess the vehicle USB ports don't deliver that much power.

[booster]

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.

I would suggest that anyone that is considering using the starting battery for backup for the coach very, very carefully consider the overall situation of power capacity and use.


Starting batteries are designed for high amperage output, and often have quite low amp hour capacity and will fail quickly if discharged very deeply a few times.


You need to look up the full specs on the battery and calculate how long you can run before getting to about 50% capacity so you have enough left to start the van. Big killer is that unless you have driven for a long time before parking, the battery may be at only 70-80% full, leaving a pretty small amount of power to use for the coach.


I built such a system early on in our power evaluation progression to supplement our 200ah battery bank, but the calculations showed the stock Chevy starting battery would give us very little usable power compared to the hassle of it all. I replaced the factory starting battery with a gp27 deep cycle battery that had about 115ah of capacity so we did have enough available to make it worth while. It was for emergency use only so only got used once or twice before we upgraded the entire system.


IMO, from a usable power and practicality standpoint unless you can significantly increase the stock starting battery capacity, you would probably be better off using a portable jump starter pack to supplement, but it would be more cost. Or you could just add another coach battery.

[rvsprinterguy]

The battery that I'm boosting by connecting the power bank in parallel fashion is the house battery, distinct from the starting battery under the hood. The power bank is a Goal Zero Yeti 1000x with a lithium battery and a regulated 12-volt output. Running it until it's flat should not damage it.

[Urlauber]

Agreed. I didn't suggest or want to discuss using the chassis battery. We're talking about a separate "Power Station" or Power Bank or, as some call them, solar generator (total misnomer).

The chassis battery is great for starting the van engine and perhaps an emergency boost if the house batteries are dead and the genny needs to be started. For many reasons it's not a good idea to drain it.

External LiFePO4 battery banks in the 100AHr range are getting pretty competitive price-wise, and I wonder if there is a simple way to use them to extend the energy supply of the existing coach battery/batteries.

Basically a Li system on the cheap.

[Urlauber]

After some googling/youtubing (or whatever that's called) I found confirmation that YES, I can just plug the Power Station into the 12V port and it will feed the camper! Love that simplicity.

However (isn't there always) a few gotchas:

1) The camper power switch (AGMs) has to be OFF while doing that. I am not sure what happens if it is on... best case a fuse blows or the Power Station turns off. Worst case?

2) The output of the Power Station is only 10A (120W) max for the 12V side so I will have to watch that. Fridge is 45W I believe, plus the fan or the heater (Truma), time will tell if that gets to its limit.
(Yes I know I can plug the camper into the 110V of the power station, but I don't want to do that since the inverter eats up quite a bit of the juice, and I don't really need 110V).

3) In the WWTT (what were they thinking) department - my RV has one single 12V outlet, and it is located extremely inconveniently. Once I plug in the Power Station I can't run anything else on 12V. Blah.

There are probably a few more I can't think of, but will experience soon.

[@Michael]

Originally Posted by Urlauber

1) The camper power switch (AGMs) has to be OFF while doing that. I am not sure what happens if it is on... best case a fuse blows or the Power Station turns off. Worst case?

Just off the top of my head - if the voltage at the output of the power pack is less than the voltage of the AGM bank, no power will flow from the power bank. If the AGM voltage is lower than the power bank voltage, the power bank will charge the AGM's at either the max that they can absorb, or the max output of the power bank.

Whether or not damage occurs to the power bank would depend on the circuitry in the power bank - if they have protection against incoming voltage out the output ports.

[Urlauber]

Did a quick test via the 12V cigarette lighter port and indeed - the camper can be powered easily that way.

The fridge - when the compressor is running - eats about 70W. The Truma heating (fan) about 20W. Both cycle on and off.

The Propane solenoid takes about 12W, and other stray currents maybe 8W.

So... quick math says max would be 110W, so just under the 120W max output. Would need to be careful with lights etc to not overwork the port of the power station.

Next step: find a way to connect a wire to the fuse panel. That wire then goes to a DPDT switch which connects to the charging port and output port(s) of the power station.

There is some space between the sofa and drivers seat, seems perfect to situate the LiFePO apparatus. The switch can be attached to the sofa support panel, and the fuse box happens to be not too far off in that same area.

[booster]

Originally Posted by Urlauber

Did a quick test via the 12V cigarette lighter port and indeed - the camper can be powered easily that way.

The fridge - when the compressor is running - eats about 70W. The Truma heating (fan) about 20W. Both cycle on and off.

The Propane solenoid takes about 12W, and other stray currents maybe 8W.

So... quick math says max would be 110W, so just under the 120W max output. Would need to be careful with lights etc to not overwork the port of the power station.

Next step: find a way to connect a wire to the fuse panel. That wire then goes to a DPDT switch which connects to the charging port and output port(s) of the power station.

There is some space between the sofa and drivers seat, seems perfect to situate the LiFePO apparatus. The switch can be attached to the sofa support panel, and the fuse box happens to be not too far off in that same area.

My thought would be very careful if you start pulling a continuous 10 amps out of the a "lighter" style power port. I have seen them get very, very hot on as low as 6 amps continuous. The quality of the ports themselves has gone severely downhill in the recent 10 years or so and they are now just plain poor in nearly every model I have seen. I have replaced ours 3 times now to try to get some that stay connected and don't get too hot.

[Urlauber]

Agreed... I am planning to pull the max 120W out of two 5.5x2.5mm outlets (Power Station has those two plus the lighter port). I bought some fitting plugs which I will solder onto some 14AWG wire. I hope that will be sufficient.

There shouldn't be a problem combining the two 12V outlets... right?

[Urlauber]

I have been testing this power station and various connections to and from the RV and it is working well.

Initially I bought this mainly to use up excess energy from the RV solar panel and to have a convenient backup to run the refrigerator/internet in my house in case of power outages. Of course, I can also plug things directly into the RV via a long extension cable.

But the more I thought about it, the more I like it as an extension of the existing coach batteries. There are two 100Ah AGM batteries. In Summer, when parked in full sun, the 200W solar panel keeps up with the energy usage (fridge, fan, lights, charging phones, propane solenoid, etc).

However, in Winter (shorter days, lower sun, Truma Heater running) or when parked between trees or otherwise shaded, the batteries will only last for a day or two.

This is where I see the 1200Wh power station come in. As far as I know, AGM batteries can only be run down to 50% of their capacity (maybe more as an exception), so adding the LiFePO power station doubles my energy supply. Not bad.

I am hooking it up via a DPDT switch which can be off, charging the power station, or electrifying the camper. It connects to the fuse panel, using an empty spot with a 15A fuse. Need to be careful not to switch the power station to "Camper" while the main switch is on. At least 3 ways to prevent that: pull the fuse, switch the DPDT switch to 0 or charging, and/or unplug the cables from the power station. I am putting that switch into a location where it should not get accidentally flipped.

Going on longer trips where I regularly drive distances and/or stay at full hookups, I won't need the power station. But to stay 3 or 4 days at a dry camp/boondock/dispersed, I can see it improve the situation. I don't really like to run the generator to charge the batteries, always seems a bit wasteful to me.

Anyway... hope everyone has a merry Christmas or whatever you celebrate.

[booster]

Originally Posted by Urlauber

I have been testing this power station and various connections to and from the RV and it is working well.

Initially I bought this mainly to use up excess energy from the RV solar panel and to have a convenient backup to run the refrigerator/internet in my house in case of power outages. Of course, I can also plug things directly into the RV via a long extension cable.

But the more I thought about it, the more I like it as an extension of the existing coach batteries. There are two 100Ah AGM batteries. In Summer, when parked in full sun, the 200W solar panel keeps up with the energy usage (fridge, fan, lights, charging phones, propane solenoid, etc).

However, in Winter (shorter days, lower sun, Truma Heater running) or when parked between trees or otherwise shaded, the batteries will only last for a day or two.

This is where I see the 1200Wh power station come in. As far as I know, AGM batteries can only be run down to 50% of their capacity (maybe more as an exception), so adding the LiFePO power station doubles my energy supply. Not bad.

I am hooking it up via a DPDT switch which can be off, charging the power station, or electrifying the camper. It connects to the fuse panel, using an empty spot with a 15A fuse. Need to be careful not to switch the power station to "Camper" while the main switch is on. At least 3 ways to prevent that: pull the fuse, switch the DPDT switch to 0 or charging, and/or unplug the cables from the power station. I am putting that switch into a location where it should not get accidentally flipped.

Going on longer trips where I regularly drive distances and/or stay at full hookups, I won't need the power station. But to stay 3 or 4 days at a dry camp/boondock/dispersed, I can see it improve the situation. I don't really like to run the generator to charge the batteries, always seems a bit wasteful to me.

Anyway... hope everyone has a merry Christmas or whatever you celebrate.

We have discussed the question of how deep AGM batteries can be discharged extensively on this forum.


Bottom line, based on all the data we found, is that the 50% rule is an extreme exaggeration. It does not reduce the battery by 1/2 as claimed.



Long story short is if you look at battery life as the total number amp hours in vs amp hours out of an AGM battery, discharging to 20% on every cycle would only reduce life by somewhere around 15%. The cycles also average so one cycle down to 80% would balance that out to be same as two at 50% in terms of battery life.


There is a ton over information and data in those the discussion threads, so if the geek in you get bored there is plenty to read.

[Urlauber]

Yeah I know, just trying to justify my purchase.

[booster]

Originally Posted by Urlauber

Yeah I know, just trying to justify my purchase.

That works

[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.