2022 2108FBS With Solar...Upgrade To Lithium

[jeffandtobi]

Hello, please excuse me if this topic has been discussed before, I couldn't find answers to my exact situation...details below:

Background: I just purchased a new 2022 2108FBS which includes the Solar Panel / Charge Control Monitor upgrade. My info about the Solar charge controller (GP-PWM-30-SQ) is that it can be set to 6 battery types, one being LiFePO4. I am hoping to simply replace the AGM battery with a LiFePO4 battery (and not have to upgrade any controller(s)).

1) Is the Solar charge controller the only charge controller, i.e. all charging sources (solar and electric) go thru this controller? And hence, I can simply swap out the batteries and change the battery type...good to go?

2) Or, Is there also another charge controller for the electric / AGM circuit, that is most likely not lithium compatible (that would be included with the base version of this camper)?

Thanks

[Marine359]

Base version can charge any lead acid battery, including 6v GC, 12v AGM, or marine deep cycle, but it will do so slowly because the stock charger is low amperage. You can swap out the charger/converter for an upgraded WFCO that can be programmed for all battery types. Keep in mind, upgrading to LiFePo is non-trivial, both in terms of cost, and in terms of effort if you want to do a DIY. DIY will take 25-30 hours if you don’t goof up.. additionally, if you’re gonna spend the bucks for LiFePo4, you might as well go ahead and upgrade to a hybrid inverter/charger, which will charge the lithiums at lightning speed. (About four times as fast as lead acid). It also involves routing ac wiring through the floor, under the chassis and back up through the floor. Once completed, the conversion to LFP is a dream. Cost of parts and pieces about $2,000 including 200ah battery, inverter/charger, cables, etc etc. there are several of us on this forum who have done this DIY, and I think all will tell you that if you have skills and tools, it’s not real hard, but it can throw you some curveballs. You can actually drop in a LFP replacement for the stock marine deep cycle on the tongue. However, you’ll not be able to use it to its full advantage because it will not charge to 100% SOC with a charger that doesn’t support LFP charge profile.

Solar charge controller actually have nothing to do with battery type, or your converter/charger except that LFP may be able to absorb more charge amperage faster than LA. They just are wired directly to the battery, or to a bus bar. The solar array is connected to the charge controller through a breaker or fuse. It’s pretty simple. Ad use you don’t undertake LFP conversion until you are well versed in the electrical underpinnings, and you are confident in your DIY skills.

[MicroMinnie]

More than likely you’ll have 2 charge sources

1) The solar controller
2) the factory 55A shore power charge controller,.

The shore power one may not have a setting for battery type. In our case I had to do a swap on the circuit board for the shore power controller that was fine tuned for LifePO4 (like no float charge and proper LifePO4 charge voltage)

Our 2019 2108FBS fuse panel/shore charger is made by WFCO 8955 model that was factory installed.
They offer 2 circuit boards for this thing. Lead/AGM or Lithium. it’s a direct fit if you swap it out.

Don’t think it will kill your Lithium batteries if you charge them with the lead/flooded type charger but they won’t output the 14+ Volt which the LifePO4’s ideally charge at.

[powercat_ras]

For sure re-program the solar charge controller to the Lithium Battery Setting. Type 2 if it has settings for 2 different types.

For when you are on shore or generator power, the OEM WFCO will be trying to charge the batteries, too.

The problem is that Lead Acid and LiFe04 batteries have different voltage curves:

The best a typical OEM charger will do for LiFe04 batteries is to quickly get them to about 50% charge, at that point the OEM charger reads a battery voltage that it thinks tells it the battery is 80% or more charged, and drops out of the mode that puts out the higher voltage (14.4) required to fully charge LiFe04 batteries.

In the lower mode, it may more slowly charge the battery past 50 % eventually not raising the charge level at all at some point around 75 %.

So, if you want to get the benefit of that last 25 % of your new batteries capacity when charging from a generator or shore power, you will want to change your AC converter-charger to the LiFe04 type.


LiFe04 Lead-acid
100% 14.4 12.7
99% 13.4 12.6
90% 13.3 12.5
80% 13.3 12.4
70% 13.2 12.3
40% 13.1 11.9
20% 12.9 11.6

[creativepart]

Jeff, LiFePO4 battery makers like to refer to their products as “drop in” replacements for Lead Acid batteries. But it’s not that simple.

You will have a number of decisions to make about charging and placement and optionally other equipment such as inverters and wiring, if you choose to go that route.

Keep asking questions and reading both here and at other RV websites like www,irv2.com. You’ll find lots of answers on YouTube, as well. Keep in mind that your questions are not exclusively about your exact travel trailer and these issues apply to most RVs. Once you learn about all the implications of this change then you can zero in on how they impact your specific TT.

[Marine359]

A few other comments Jeff, which you may find helpful.
The most important things you should decide before spending ANY money on upgrades are:

1. How long do you realistically believe you will own your trailer. Many or most RVers sell or trade their RVs within 3 years of purchase. So, it’s not a real good idea to perform upgrades that you may not be able to cash in when you sell or trade.

2. How will you use your trailer a majority of the time. You won’t get your money’s worth out of expensive upgrades that either you won’t use often, or can live without. Try to estimate what percentage of your trip days will be without hookups. And how many consecutive days of camping with hookups you’re likely to experience. If you’re not going to do much boondocking, spending on expensive battery and solar upgrades is mostly wasted.

3. Since you bought a 2022 Micro Minnie, most of your upgrade focus should be on the most cost efficient way to “feed the fridge”. Your 12v compressor fridge will limit the number of consecutive days you can boondock without generator use. The stock Micro Minnie has trouble just going one day. So, you first upgrade should be a batter battery or multiple batteries. If you don’t plan much boondocking, just stick with more amphrs of lead acid. That will obviate the need for upgrades needed to support a LiFePo4 installation. The fridge will use 50amphrs per day. So, use that consumption figure plus 20amps for everything else, to estimate your power storage and production needs.

4. Leave enough in your budget to buy a generator. It’s your best friend because a modest battery upgrade will leave you with a depleted battery when there’s no sun. It’s the mandatory back-up plan. Spending a little more to get an easy start for your A/C will allow you to buy a generator as small as 2000w and still run the A/C. The cost of a small generator plus the cost of an east start will be less than the cost of a larger generator that will run the A/C without an easy start. Plus you’ll burn far less fuel and it will be easy to store.

[Thindirtline]

I just bought a 2022 2108TB and put in a 100ah LFP battery. I changed the solar charger to lithium and the power converter automatically senses the battery type. My unit has the 190 watt solar panel. I mounted the battery on the inside below the bed about one foot back from the original battery. On a cold morning below freezing an external LFP battery would be damaged if being charged by the solar or power converter. Your tow vehicle may need a dc-dc converter if the alternator can’t handle the high current to charge an LFP battery. You also will want a battery disconnect switch to prevent battery charging from the solar which occurs even if your main battery switch is turned off.

[BobC]

Originally Posted by powercat_ras

The best a typical OEM charger will do for LiFe04 batteries is to quickly get them to about 50% charge, at that point the OEM charger reads a battery voltage that it thinks tells it the battery is 80% or more charged, and drops out of the mode that puts out the higher voltage (14.4) required to fully charge LiFe04 batteries.

Am I correct in thinking that, if one has solar in addition to a generator and some form of 120V shore-power charging that lacks a LiFePO4 profile, the 120V based charger or generator will rapidly bring your batteries to about 80% and the solar controller/charger will do the rest?

Clearly this would only be the case with adequate sunlight.

If so, changing out the converter/charger or inverter/charger would seem to be less of a priority.

[Marine359]

First, you do not need a dc/dc controller to protect your tow vehicle alternator from charge amperage being demanded by LiFePo4. The 7-pin is only going to deliver 3-5 amps. Installing a dc/dc controller with associated wiring is much more expensive than just installing some solar. You can do it, but why bother when all you need is enough battery voltage to run your rv, including compressor fridge.

When LFP is over 80% SOC, an OEM charger will not take it any higher, because LFP cannot absorb the standard float amperage/voltage. Similarly, if battery voltage of LFP is above 13.5 volts. A solar charge controller may not provide any charge amperage at all because it needs to see a 5v delta between pv voltage and battery voltage A typical 100w panel outputs 18.5v or less. And a LFP reaches 100% SOC at about 13.6 v. While charging it may say 14v, but the battery likes 14v charging, but doesn’t hold at that level. As soon as you remove charge voltage it will drop to 13.6v. I’ve found that when my LFP is near 100%, or let’s say above 90%, solar doesn’t do anything. At that level of SOC, only my lithium profile charger will take it to 13.6v, 100% SOC.

[Thindirtline]

Glad to hear that the charging current to a trailer LiFePO battery through the 7 pin connector will be low and should not damage my truck alternator. Question: did you measure this current yourself? I installed a 100ah battery and not a 200ah battery in my new Micro Minnie because I read elsewhere that this current could be high and tax my alternator. I did not want to install a dc-dc converter. I don’t have the ability to measure this current myself. Also, I don’t know yet if my 100ah battery will be enough as it is too cold to camp right now. I do have the absorption fridge, 190W solar, and am pretty frugal with power.
Thanks for being so helpful on all of these threads.
Scott

[Marine359]

Yes, I measure at 7-pin disconnected. And, I also checked my smart shunt while connected and didn’t notice a high amperage while compressor was running. Maxed out at 4amps. I been using this leaving my fridge on while traveling. It always seems that battery voltage is the same when I leave to when I stop driving. So, usually, I start the day with 100% SOC, and I’m at 100% SOC when we stop driving for the day. That indicates to me that the 7-pin is not charging the battery at high amperage, but is simply providing enough to run the condenser when it turns on. I dunno, I could be wrong about this, but it’s been working without mishap for about 2 years.

[Thindirtline]

If your trailer battery was really low before you hook up and start driving I would guess that you could get a much higher charge current than 4 amps though I am not sure. Perhaps the resistance in the wire from your tow vehicle battery to your trailer battery would help limit this current.
This is the situation that I am concerned about with my new lithium battery. I think the current could be higher with a larger lithium battery like you have.

[Marine359]

Wish I knew the answer to that question. Not often that I start driving with a very low SOC, but I have at times started driving after a couple days of boondocking with no generator. Have also gone to zero SOC while driving. This happened when I goofed and left my Inverter on while my A/C was on. The inverter would run the A/C until my battery was drained. But there didn’t seem to be any I’ll effect on my alternator.

[Fred 2106DS]

Originally Posted by Thindirtline

If your trailer battery was really low before you hook up and start driving I would guess that you could get a much higher charge current than 4 amps though I am not sure. Perhaps the resistance in the wire from your tow vehicle battery to your trailer battery would help limit this current.
This is the situation that I am concerned about with my new lithium battery. I think the current could be higher with a larger lithium battery like you have.

Scott,

Here's a link to the 7-pin and DC/DC charger tests I ran earlier this year with my Tundra and 200AH LiFePO4. There was no issues with the charge current flowing through the 7-pin even with the LiFePO4s at 40%.

Fred

[Thindirtline]

Thanks for the reply. Glad to know my alternator will likely be ok. I am going to look into measuring the charging current myself. I have a nice multimeter.
Scott

[jonnyr1]

Originally Posted by Thindirtline

I just bought a 2022 2108TB and put in a 100ah LFP battery. I changed the solar charger to lithium and the power converter automatically senses the battery type. My unit has the 190 watt solar panel. I mounted the battery on the inside below the bed about one foot back from the original battery. On a cold morning below freezing an external LFP battery would be damaged if being charged by the solar or power converter. Your tow vehicle may need a dc-dc converter if the alternator can’t handle the high current to charge an LFP battery. You also will want a battery disconnect switch to prevent battery charging from the solar which occurs even if your main battery switch is turned off.

Hey there,

I'm planning to do the same on my Mini 2301BHS. Do you have any info you'd be willing to share about extending the wiring to allow the new battery location?



Thanks,

[Thindirtline]

Here are pics of my lithium battery install in my Micro Minnie.
I used the original battery cables that came with the trailer.
Scott

[Marine359]

Originally Posted by jonnyr1

Hey there,

I'm planning to do the same on my Mini 2301BHS. Do you have any info you'd be willing to share about extending the wiring to allow the new battery location?



Thanks,

If you are referring to the ac wiring, AND you plan to mount an inverter/charger and battery in the pass thru, you’ll need to run the ac cables through the floor down along the frame rail and up through the floor again under the kitchen sink.

[Marine359]

Originally Posted by Thindirtline

On a cold morning below freezing an external LFP battery would be damaged if being charged by the solar or power converter. Your tow vehicle may need a dc-dc converter if the alternator can’t handle the high current to charge an LFP battery. You also will want a battery disconnect switch to prevent battery charging from the solar which occurs even if your main battery switch is turned off.

It is currently below freezing outside, and I am charging my LiFePo4 thanks to the 12v holding tank heater I installed under and around my battery. In the photo, you can see a lighted switch which is wired to the tank heater.

In the second photo, you need to install a breaker between your solar panels and the charge controller. Then also a fuse between charge controller and battery. In the third photo, notice my charge controllers are wired to a spade fuse block, which in turn is wired to my bus bars.

[sorry second photo, the breaker picture is sideways]. It’s mounted right next to where the solar wiring exits the front bulkhead.

[R1campr]

Marine359, what is the brand of that breaker? Its what I’ve been trying to find.