Question Questions Regarding Upgrading to Lithium

[Nomadist]

Hi, everyone. I'm upgrading my current system, which is the stock one that comes with a 1997 Four Winds rig, to one that includes lithium batteries.

I've settled on the Ampere Times 200ah battery for its cost-effectiveness (< $1k) and low-profile:
12V 200Ah Lithium Iron LiFePO4 Deep Cycle Battery, Built-in 100A BMS, 2000+ Cycles, 280amp Max
https://www.amazon.com/dp/B088RM4W48/?tag=rvf01-20

Now I need a lithium charger. At the same time, I'd like it to be an inverter. For that to work seamlessly, it should have a transfer switch built in. Here is one with the wattage and price I want.

AIMS Power PICOGLF12W12V120AL Green 1250W Power Inverter Charger with Transfer Switch
https://www.amazon.com/dp/B076ZQ9TP2/?tag=rvf01-20

So far, the same unit has:
• a charger
• an inverter
• a transfer switch

Here is my question: do I need to upgrade the converter that comes with the RV? It's the Model 6345 that has been retrofitted with the 7345 RU electronics:

Any input is appreciated!
-André

 

[RandyB]

It may be a case of semantics, but my understanding is that an inverter takes a DC input and changes it to an AC output, while a converter takes an AC input and changes it to a DC output. The converter is generally considered the battery charger. Since the AIMS unit appears to be an inverter/charger/transfer switch, the current converter needs to be taken out of the equation and isolated from your new setup. Since the existing converter looks to be incorporated into your DC distribution panel, some wires will need to be disconnected, or a circuit breaker might need to be permanently turned off (the far right circuit breaker labeled conv).

 

[Kevin D Pem]

Hi, everyone. I'm upgrading my current system, which is the stock one that comes with a 1997 Four Winds rig, to one that includes lithium batteries.

I've settled on the Ampere Times 200ah battery for its cost-effectiveness (< $1k) and low-profile:
12V 200Ah Lithium Iron LiFePO4 Deep Cycle Battery, Built-in 100A BMS, 2000+ Cycles, 280amp Max
https://www.amazon.com/dp/B088RM4W48/?tag=rvf01-20

View attachment 4069

Now I need a lithium charger. At the same time, I'd like it to be an inverter. For that to work seamlessly, it should have a transfer switch built in. Here is one with the wattage and price I want.

AIMS Power PICOGLF12W12V120AL Green 1250W Power Inverter Charger with Transfer Switch
https://www.amazon.com/dp/B076ZQ9TP2/?tag=rvf01-20

View attachment 4070

So far, the same unit has:
• a charger
• an inverter
• a transfer switch

Here is my question: do I need to upgrade the converter that comes with the RV? It's the Model 6345 that has been retrofitted with the 7345 RU electronics:

View attachment 4071

Any input is appreciated!
-André

Looks like you may have done your research and math. consistant 100a at 12v is 1200w the size of your inverter choice. You do not want a three stage charger for your lithium. Lithium asks for cccv charging (constant current, constant voltage) Your battery spec tells you the voltage you need to set your charger up for. Chargers work together and so both can be in the circuit as long as they have a lithium setting. the lithium setting simply takes the smarts out of a smart charger and allows you to set charging voltage.

You are on the top of the heap using Magna or AIMS low voltage low freq inverters. Should you allow the BMS to register low voltage and shut the battery down, time or a simple trick can jump start the battery.

 

[Nomadist]

Thank you @RandyB and @Kevin D Pem. After I posted my question, I also read in other places that I'll need to shut down (bypass) the converter in my unit in favor of the charger in the new unit so your information was spot on. And I didn't know what the difference was between a lithium and non-lithium charger; thanks for that detail. It appears the voltage the lithium battery will want is 14.2V.

I was also lucky to find someone else attempting to do exactly what I want to do over on a DIY solar forum. I added my details in case it helps others. I'm particularly pleased with my generator purchase so far since it allows my A/C unit to start without any modification. Regarding the new-on-the-market Ampere Time battery, the other fellow who purchased it responded and said that he's still happy with his purchase.

Trailer LifePo4 Upgrade + Add an Inverter + Solar in Future

Trailer LifePo4 Upgrade + Add an Inverter + Solar in Future

Hi all, We have a Jayco X23B Trailer that came with a WFCO 8735 Converter/Panel and a standard 60AH Battery. I recently ordered 8x 280AH Cells to build (2) 12V 280AH LifePo4 Batteries for a 560AH Upgrade. While doing some research, I have found out that our WFCO Converter/Panel will only charge...

diysolarforum.com

I'm probably ok with the 1200W inverter but I think I'll examine a few more power scenarios before I purchase it; adding another battery in parallel would give me 200amps of continuous draw so perhaps for some future proofing I should move to 2000W:

https://www.amazon.com/dp/B00I36K1VQ/?tag=rvf01-20

This fellow's experience with the fan and overheating and poor customer support is concerning, though:

Weak, flawed (oveheats) poor customer service
Reviewed in the United States on November 24, 2017
Size: 2000 Watt Single PhaseVerified Purchase
I have had this .... doorstop ... for about two years, and I cannot in any way recommend it.
We live off-grid, in a low-footprint model. This device was intended to serve our power needs, but also charge our batteries with a generator, if the sun vanished for a few days - which, living in the sticks of the East Coast of Canada, it does.

I have developed the same issues as other AIMS models (I thought I had done my research, but alas): it overheats, and cannot generate any notable power without shutting down.

The first issue came about a year ago, when the fan simply died. Fortunately, I had access to a spare computer, and was able to install a new fan. Then in August of this year, I tried out an induction element, which draws a max of 1,200 watts. At the time, the fan came on, and stayed on all the time - which, given that we live in 500 square feet makes for a bit of noise.

Last week, the inverter overheated and shut down, while in the generator mode. The negative terminal now grows incredibly toasty at the slightest application of power, either charging or discharging.

Today, it overheated and shut down twice: it now can't even handle a 250 watt crockpot.

DO NOT BUY. I spent $800 CDN on a piece of junk that gives out about as much power now as an old 300w Morningstar. Should have gone with an Outback or Xantrex. My old Prosine could power the woodsplitter without issues, this thing shuts down instantly.

As a guy with a fair bit of electrical savvy, I have replaced the fan myself (again). However, I expect it to last about a year or so, before it bakes again.

Oh, and a further update:: the plastic bridge that allows hard-wiring has melted, and the customer service department has ignored any queries. Again.

I'm perfectly happy paying more for quality and customer service. The last thing I want is to be boondocking and have the unit fail on me.

 

[Kevin D Pem]

I'm perfectly happy paying more for quality and customer service. The last thing I want is to be boondocking and have the unit fail on me.

Aims is a good brand. What you are reading is an inverter in a hot environment, or undersized for the load being applied. Even if the wire size is large enough the lugs used may be under size making the connection heat up. I use a 3000w inverter and do most anything with it. If the inverter detects a faulty fan, low voltage mostly because wire size is small, or loose lugs it will kick out. If you want reliable make sure you use good thick lugs on the over sized cable. That the inverter is larger than you need. mine is twice as big as I need. After you mess up the traces on the circuit board or fry the connecting terminals you can't expect anything to be reliable. It is not the fault of the manufacturer that one trys to use a small piece of equipment to do more than it is designed for and then has problems from that day on.

Over build and the fan will not come on very often, mine only comes on when I try to run things like my welder. Over build!!!

 

[Nomadist]

Thanks for the advice, I shall take it (overbuild). I also discovered that my microwave is 1450 watts so I need to use a larger inverter, anyway.

 

[Kevin D Pem]

Hey @Nomadist just talked to my friend that has an Aims inverter. Here is what he did and it is serving him well after 8 years.

He uses a separate charger than the one in the inverter. He charges the batteries and uses the inverter for all house power.

What that does for him is allow solar assistance to a grid connection to reduce the power he uses from the grid tie. this in turn reduces his bill while connected and because the grid tie is removed from solar or inverter power so as not to have transfer switches of any kind. When using generator it is used as grid tie and is used to charge the batteries. This is vary similar to an inverter generator in that the DC generator part of the genset charges capacitors that are then fed into the inverter circuit.

He tells me that the charge circuit on the Aims can be turned off and that is what he did. His inverter is likely 5000w because it runs his split A/C unit and everything else.

 

[Nomadist]

Thanks for sharing this, @Kevin D Pem.

Interesting that he went that route (disconnecting the charger). I came across this reviewer on Amazon who installed the AIMS on his boat. He recommends splitting the functions but for reliability reasons:

Here are what I consider the main flaws:

1. There is no way to intermittently charge without running the inverter. If you use power save, then the inverter runs when the power goes out, draining your batteries. This is terrible for unattended use, as when someone unplugs the cord, you have a reasonable drain on your batteries.

2. The device is too sensitive to AC voltage. Commercial AC is 120 +- 15%. A lot of marinas use that higher voltage, especially at night, to cover losses during the day. Anything over 131 and the charger shuts down, again draining your batteries (see #1)

3. There is no power share. This means if you want to charge at full power off a limited generator, you may not be able to run anything else or it overloads the generator.

4. It's not reliable. First to go was the power save mode, now the entire charger is not working. The inverter still works but it will soon be a heavy paperweight for me.

5. The remote display is almost useless. No amps in or out. No charge state info (it just says charging but it could be in float).

I didn't use the auto start features and didn't use tech support since installation was super easy. The manual wasn't great though.

Looking at each of his issues one at a time:

1. This is a fair criticism but seems like it applies to his marine dock situation more than mine.
2. Ok. This ought to be unique to the AIMS unit.
3. If I'm reading this correctly, it's not possible to get power from the batteries and the generator simultaneously for larger draw uses. I don't think my setup below can do this, either. This might be useful for me because I've discovered that my generator is overloaded with the microwave on but not with the AC. Getting 80% from the generator and 20% from the battery might be handy.
   
   The alternate way to do it is how your friend set his up: get all the power from the batteries and just let the generator fill up the battery. Might be the easiest/cheapest way to power the microwave thus saving me searching for a power-sharing transfer switch.
4. That's not good. But all equipment fails so without knowing the sample size there isn't enough to go on.
5. Ok.

At first I liked the idea of an all-in-one unit. Now I see the utility of having separate devices. Yes, it's more work to install but if one component fails it should be easier to replace. I'm looking for ways to increase reliability and separate components seems like a prudent strategy for that.

So, something like this would work (haven't settled on the brands, just assembling the pieces):

• Go Power Industrial Pure Sine Wave Inverter - GFCI - 2,000 Watt - 12V ($593, 3,500 starting watts; should handle the microwave)
• Progressive Dynamics Inteli-Power RV Converter and Battery Charger - Lithium - 12V - 60 Amps ($214; should handle the lithium battery)
• Progressive Dynamics Transfer Switch ($122; switches between shore power/generator and the batteries)

I'm just not sure how I feel about running everything through the battery—including the A/C when I'm hooked up to shore power/my generator. A power sharing transfer switch would truly be ideal.

 

[Kevin D Pem]

Thanks for sharing this, @Kevin D Pem.

Interesting that he went that route (disconnecting the charger). I came across this reviewer on Amazon who installed the AIMS on his boat. He recommends splitting the functions but for reliability reasons:

Looking at each of his issues one at a time:

1. This is a fair criticism but seems like it applies to his marine dock situation more than mine.
2. Ok. This ought to be unique to the AIMS unit.
3. If I'm reading this correctly, it's not possible to get power from the batteries and the generator simultaneously for larger draw uses. I don't think my setup below can do this, either. This might be useful for me because I've discovered that my generator is overloaded with the microwave on but not with the AC. Getting 80% from the generator and 20% from the battery might be handy.
   
   The alternate way to do it is how your friend set his up: get all the power from the batteries and just let the generator fill up the battery. Might be the easiest/cheapest way to power the microwave thus saving me searching for a power-sharing transfer switch.
4. That's not good. But all equipment fails so without knowing the sample size there isn't enough to go on.
5. Ok.

At first I liked the idea of an all-in-one unit. Now I see the utility of having separate devices. Yes, it's more work to install but if one component fails it should be easier to replace. I'm looking for ways to increase reliability and separate components seems like a prudent strategy for that.

So, something like this would work (haven't settled on the brands, just assembling the pieces):

• Go Power Industrial Pure Sine Wave Inverter - GFCI - 2,000 Watt - 12V ($593, 3,500 starting watts; should handle the microwave)
• Progressive Dynamics Inteli-Power RV Converter and Battery Charger - Lithium - 12V - 60 Amps ($214; should handle the lithium battery)
• Progressive Dynamics Transfer Switch ($122; switches between shore power/generator and the batteries)

I'm just not sure how I feel about running everything through the battery—including the A/C when I'm hooked up to shore power/my generator. A power sharing transfer switch would truly be ideal.

Let me start by saying this. If the inverter askes for more power than the line power is supplying lets say 50A service with a converter that supplies 12v at 60 amps about 720 watts the extra wattage will come from the battery. if the battery is fully charged and the inverter only requires 720 watts then the batteries will maintain their charge and all power will be supplied by the converter. Ask if this makes no sense to you, I sometimes don't explain my self well. it is about resistance and voltage levels.

When I talk about low frequency inverters, there are low frequency and high frequency units. When talking to an engineer about reliability what he told me was high power diodes do not work well at high frequency. The failure rate of high frequency inverters comes from this components inability to handle the load at the frequency it is asked to handle it. He let me know that High frequency inverters by design flaw will last only 1.5 years when on all the time. The low frequency unit because the high power components have no problem with the frequency will last at least 10 years. This is a link that might help you make a choice. News|Low-Frequency Inverter VS High-Frequency inverter|Solarbaba Expect the weight to be quite high because of the transformer weight. Oh yes, standby power drain is better with low frequency inverters.

I leave my inverter on all the time. I run one at a time; my table saw and other power tools. I use my mig welder with it. I have done the same using a high frequency inverter but would fight to get my table saw running at times. The other reason I would not buy another high frequency inverter was the roughly 1 year life. I am on my 4th year with my low frequency inverter.

If they don't say low frequency because it is such a sale tool, it is likely not. Compare weights between units. the low frequency unit will be about 3 or more times the weight of the high frequency unit. and more expensive, but cost will be equally low after about 4 years so a very good deal. I could and would explain my system if you ask, you might have to look long and hard to find another like it.

 

[Nomadist]

I'm convinced on the low-frequency inverter, thanks for the education @Kevin D Pem . I read your article on high-frequency inverters plus some others and they do have a reputation for being cheap—and unreliable.

And I do understand how the load will pull what it needs from both sources. At first I thought you were suggesting everything go through the battery and inverter, as shown in the All Battery/Inverter diagram below. It would incur unnecessary losses when using shore power (AC shore power -> converter -> charger -> battery -> inverter -> back to AC) but perhaps that's not really a big deal since that's unlimited power. Would it wear out the inverter and converter/charger more quickly? I don't know. It does have the benefit of being (slightly) more simple than the second model.

But I then I re-read your comment and considering that it's not much more complex, I think you were suggesting a model more like the one below (Automatic Transfer Switch Model). The switch will take power from AC4 or AC5 if AC4 voltage drops (i.e. shore power is disconnected). If shore power is plugged in and there is a high AC load, it's likely the load will mostly come from shore power but, as you mentioned, the battery is also available to help—though that would be a very large AC load to use power from shore power and the battery.

In both models, the 7345 is reduced to a junction and fuse box; I use neither the inverter nor the converter.

The only problem with this design is that DC comes only from the battery and never from shore power. I think my RV currently can get DC power from the shore so perhaps I'm missing an automatic switch that could select between DC2 and DC4 (perhaps there is one in the 7345?).

As for loads, most DC loads are typically low and 200AH in the battery seems like quite a lot. On the other hand, the portable freezer must always have DC power, so that's a constant albeit low draw.

Other loads are:

• propane furnace blower (is this AC or DC? and how many amps does it draw? need to find out even though it's intermittent)
• Webasto gas heater blower (this is DC; only about a 2A draw when it's on but it too is intermittent)
• microwave (@1500W); since I use this only for heating things up, the battery should not get drained quickly
• electric pressure cooker; this could pull 1200W for 30 min to get the food to temperature and pressure then much less to complete the cooking. But even here (0.75 hr x (1200W/120V = 10A) = 7.5A. That's only 7.5/200 = 3.75% of the battery capacity.
• laptop (60W when charging)
• cellular modem (5W)
• DC LED lights (maybe 20W?)
• computer display (70W and always drawing when on)
• not the AC unit; it's way too much of an energy hog and I know I will be running the generator every time I use it
• I don't use a hair dryer
• I would use an electric heater only when shore power is available
• in the rare occasions of needing high power for long durations, I'll just fire up the generator.

The benefit of both these models is that the portable freezer has access to battery without interruption. The freezer can't experience a power interruption when there is frozen food in it (I plan to do a lot of boondocking).

From watching the experience of others on Youtube, my guess is that a full battery (200AH):

• in winter
• using the Webasto heater
• using DC LED lights
• using the laptop and display and modem

Would deplete in about 3 days.

Given the above, I'm leaning toward the Automatic Transfer Switch Model.

How does all this sound? Did I understand you correctly?

 

[Kevin D Pem]

propane furnace blower (is this AC or DC? and how many amps does it draw? need to find out even though it's intermittent)

12vdc on the blower.

This is what I propose. Not only does my friend have his set up this way but I do, kind of. My solar and inverter/ battery bank is 24vdc and the inverter feeds the rv power cord. this handles all rv loads and charges and maintains the 12vdc battery and system native to the RV

A little about my set up. I use a refrigerator designed and built for apartment use, made by Avanti. I use a portable ice machine during the day. I use an Instant pot and inductive cook top. I have propane stove/oven and propane convective heater (not furnace). I have 1000w of my 2000w available solar. Seems that my almost identical solar controllers don't play together well, so I am waiting for another controller to get here.

With each RV I get I move my system from one to another as I store the unused RV. I have been using this type of set up for about 7 years with no problems. I have also set up such a system for at least 5 other RVers. Only difference between others system and mine is the choice to set up my solar as a 24 volt system, both systems work equally well, I just find adding a independent solar system simplifies the operation as only seldom do I need to plug into the grid and if I do I simply disconnect from inverter and connect to generator/grid.

One more note. I live off grid with my RV. Other than a 2 mo. stent while recovering this last year I could count the number of times I was on the grid sense 2003 on my fingers.

 

[Nomadist]

Ah, so you are suggesting the All Battery/Inverter Model. I'll do some investigation into that.

 

[Kevin D Pem]

Ah, so you are suggesting the All Battery/Inverter Model. I'll so some investigation into that.

Yes I am. I tried to modify the drawing more clearly but allas my software is not up to snuff. So I will show you.
Keep in mind that your charger has higher voltage than the battery produces. What that means is most power will come from the higher voltage connection. When the voltage sags from the 60a charger due to a higher load that It will produce, the remainder of that load will come from the battery. I keep saying this a little different so one of my comments will hit the spot.

I am building a box for this but for now I have power, Living in the same place you are remoding takes some adjusting. This is a 24v inverter, notice I have the house cord connected to the inverter. If I were running a 12v system I would disconnect the charger from the house wiring and run charger cord to the grid or genset If I were using one. My solar keeps up with my loads so I don't even have a cord run outside. I would do that by unplugging the cord from the inverter and sending it outside to plug in. Other than solar I only have a 24vdc poor boy generator that is connected directly to the battery from outside access door. I must admit however that the generator is in storage at this moment. I will have access to storage later today if that generator is of interest.

 

[Nomadist]

I asked around and I don't think this system will work for me. I understand why it works for you but here are the drawbacks for my situation:

Drawbacks of All Battery/Inverter System​

• unless plugging into shore power is rare, this shortens the lifespan of the battery even when plugged in since lifespan is best thought of as contingent on "power throughput over the life of the battery." Interestingly, this is the same thing when measuring refined carbohydrates (flour, sugar, etc.) in humans, too; the more refined carbohydrates through the body over the lifespan, the more damage and therefore the lower the human lifespan or at least lower healthspan.
• there are several single points of failure: converter/charger, inverter, battery. If any of those fail, I lose access to AC power
• the currently spec'd inverter is not large enough to run my air conditioner whereas the air conditioner will always start from shore power; said another way, I would have to greatly increase the size of the inverter to be able to run the a/c when plugged into shore power thus raising the price

On the other hand, using shore power/generator through a relay permits unlimited use of high-power loads such as:

• the air conditioner
• electric heater
• microwave
• electric pressure cooker

without stressing any of the other components of the system.

My guess is that the reason this works for you and the others is because you are rarely attached to shore power/generator and using an air conditioner. I expect I will be doing this often in summer. And you're comfortable with the several single points of failure...I'd like to avoid those.

 

[Kevin D Pem]

we all have our ways. I do have A/C and plug it in to shore power when needed, however a generator is used for this more than the grid. I guess what I am saying is I have my cake and eat it too because I can have both systems working at one time. The cycle life of Lithium is roughly 4000 cycles. a cycle is calculated in a calculated full discharge. Keep that calculated in mind as there is no suggestion full discharge is in anyway acceptable.

I fully accept the 10 year life of the inverter, the expected 10 year life of the solar AGM batteries, and have extra MPPT controllers. The converter I use to maintain the 12v house battery via the inverter was new in 1983' I have spare parts for the inverter( after all I built it), but don't believe I will need them. My inverter board is 3000w but the transformer is 1500w 100% duty cycle, capable of 3000w intermittent. I too am concerned about long term life of system.

My suggestion is think outside the box. I spend my insanity that way?, but don't expect others to see it my way.

 

[Nomadist]

we all have our ways. I do have A/C and plug it in to shore power when needed, however a generator is used for this more than the grid. I guess what I am saying is I have my cake and eat it too because I can have both systems working at one time. The cycle life of Lithium is roughly 4000 cycles. a cycle is calculated in a calculated full discharge. Keep that calculated in mind as there is no suggestion full discharge is in anyway acceptable.

I fully accept the 10 year life of the inverter, the expected 10 year life of the solar AGM batteries, and have extra MPPT controllers. The converter I use to maintain the 12v house battery via the inverter was new in 1983' I have spare parts for the inverter( after all I built it), but don't believe I will need them. My inverter board is 3000w but the transformer is 1500w 100% duty cycle, capable of 3000w intermittent. I too am concerned about long term life of system.

My suggestion is think outside the box. I spend my insanity that way?, but don't expect others to see it my way.

Don't get me wrong: I do appreciate you raising this model to me because it had me think through things. I'm learning a lot through this process.

Regarding the battery life, the way it was explained to me is that the flow of electricity through the battery is what diminishes working life. We tend to think if it as cycles because that's how we use batteries but an additional way of measuring it would be, "how many amps have gone through the chemistry?" Additional diminishment occurs with every deep discharge, of course, as you point out.

But it wouldn't work nearly as well if we rated batteries as "10,000 total aH." People would immediately ask, "How many charge/discharge cycles does that work out to?" And cycle count includes the extra diminishment due to deep discharges.

And you are plugging the AC directly into shore power so even your model allows for that.

 

[Kevin D Pem]

a couple of questions:
if the voltage never goes down to chemistry storage voltage then what actually goes through the battery?

Where are you getting your data? (Website or???) will you share?