My New Lithium Battery Setup

[JackandJanet]

Most of you long-time members will recall that I have been a staunch nay-sayer regarding use of Lithium batteries in our trailers due to the high cost and my doubt that you could recover that outlay and beat what you would have paid for lead-acid batteries over the same projected lifetime.

Well, I recently had a change of mind, due to the drop in cost of many of these new battery designs, a change in chemistry (LiFePO4 vs Li-ion), and a reduction in size of the batteries, allowing me to install two of them in the same space that I had for two Group 24 lead-acid batteries. Also, the new converter that I installed has a switch that allows it to charge LiFePO4 batteries correctly.

But, just so you know, this is NOT just a simple, drop-in, PnP replacement! You DO have to set up the correct charging process for these batteries. It is different than the algorithm used for lead-acid batteries. The new converter I installed does that, but at a minimum, you need to install a DC-DC converter so that the tow vehicle's alternator will not be damaged.

I didn't take pictures of the installation, but am posting pictures of the finished system in this thread, as well as my thoughts on why I chose the components I used.

I'll show this in the next post.

 

[JackandJanet]

First, the installed batteries in the battery box in the tongue. It is rather "cluttered", so I tried to label things you might find interesting.

I already had a small water pump mounted in the lower right-hand corner of the box and the plastic tubes you see coiled over the batteries are part of this. I use PVC capped PVC tubes over the ends of these to keep them clean.

Now, the batteries are REDODO (pronounced RED-odo) 12.8V 100Ah Smart LiFePO4 batteries. They are just slightly larger than ordinary Group 24 lead-acid batteries so they cause the box to "bulge" slightly, but this is no problem. They fit and they are connected in parallel so they provide 200Ah of capacity. This is far superior to the capacity of lead-acid batteries , whose voltage drops significantly as they are used. The useful capacity of LiFePO4 batteries is at least double that of lead-acid batteries and they weigh less than half the weight of lead-acid.

I bought these batteries through Amazon, and was impressed with the packaging, build quality, instruction manual and the customer support when I had a couple questions, which were answered promptly.

You'll notice the blue rectangular box mounted on an aluminum plate at the front of the battery box. This is a Victron Orion-Tr Smart DC-DC Charger (Isolated), that is installed to prevent possible damage to the tow vehicle's alternator. The internal resistance of a LiFePO4 battery is much less than that of a lead-acid battery, which could potentially cause the alternator to overheat, by sending too much current to the battery, or, more likely, would cause the 30Amp fuse in the tow vehicle to blow. The model I bought limits the charging current to 18 Amps, (model 12/12-18), and was bought through Amazon.

I DID NOT have to buy the "Isolated" version of this charger, and SHOULD have bought the non-isolated version, which would have been a bit simpler to hook up (and possibly cheaper). With this charger, I had to add a new white negative connection to the batteries, which would not be needed with the non-isolated one.

The charger is controlled and monitored with a free smartphone app from Victron which I downloaded to my Android phone from the Google Play Store. I'm sure there's an I-Phone version as well. It connects to the charger through Bluetooth and allows you to adjust the charging voltage (14.6V) and float voltage (13.5V).

There is one other connector I've installed on the batteries, and this is a quick-disconnect connector that allows me to attach a Haisito, 20Amp Smart Charger, Model P20/20AMP/N20, which is powered by 120V shore power. This allows me to quickly charge the batteries, even with the top down, if needed, and it's designed to work with LiFePO4 batteries. I bought it through Amazon too.

More in the next post.

 

[JackandJanet]

Finally, I've labeled the two charging leads from the solar panels I installed on my trailer a long time ago. Sadly, the MPPT controller I used then was not designed to work with LiFePO4 batteries, so I had to replace it too. I ordered a new one through Amazon.

I chose a Victron SmartSolar MPPT 100/30 controller for this task and mounted it in the same place that I used for the old solar controller, on the end of the overhead cabinet on the street side of the trailer. It is shown in the two pictures here, and I apologize for the blurred second picture (I didn't hold my phone steady), but you can see how it is hooked up and mounted. The controller can accept an input voltage from the solar panels of up to 100V and it can deliver up to 30Amps to the batteries at the correct bulk charging voltage (14.6V) for LiFePO4 batteries. It is also controlled/monitored by the same phone app that I used for the DC-DC charger in the last post. The app gives a great picture of the solar charging process. It shows the current Wattage, the input and output Voltage and Amperage and then on a separate screen shows the accumulated Amp-Hours stored on the battery each day.

The connections were essentially the same as the old MPPT controller, so no new wiring was needed. It did not need, or work with, the separate monitoring screen needed with the old controller so that was eliminated.

In summary, this setup worked perfectly on my recent camping trip to a week-long boondock campsite in Utah. My batteries stayed charged during the drive to and from Kodachrome Basin and throughout the stay, with no need for supplementary generator power. Overall, I'm quite pleased with this installation and would be happy to answer any questions any of you might have.

Edit: REDODO now offers even smaller LiFePO4 batteries for about the same cost as I paid and they have the same Amp-hour capacity. There are other manufacturers that offer similar ones too. Shop around if you decide to take this plunge.

- Jack

 

[sam-HILO]

Battery change up.

We don't boondock. Just wanted to say that it was nice of you to do the write up. Some body will benefit from the information.

 

[JackandJanet]

I forgot to mention why I installed an "aluminum mounting plate" in the battery box in front of the DC-DC converter. I had two reasons for this.

First, the instruction manual says the converter can run hot - you can see the heat dissipation fins on it and I figured an aluminum plate against them would help with that heat transfer. It increases the conductive surface area and should help to keep things cool. In my recent trip though, close to 800 miles of towing, I never found the converter to be more than pleasantly "warm", when I checked it along the way.

Second, I wasn't quite sure the ABS battery box would provide quite enough support if I mounted the converter directly to it with the four mounting points provided and four bolts into the box's wall. The aluminum plate is the depth of the battery box and the bottom of it is a section bent at a 90 degree angle so that any weight is mostly supported by the floor of the battery box. This also raises the converter off the floor, which helps air circulation over the fins. Then, the converter is mounted to the plate and the plate is attached to the box by two bolts at the top, which don't really have to support weight - they just keep things in place.

- Jack

 

[Johnnie-HILO]

I have been thinking about upgrading to lithium batteries on my trailer. I have two 100 ah agm batteries and two 100 watt solar panels. One free standing panel and one on my roof. If I up grade to lithium I would have to do something with my truck alternator, replace my Elixir Power Converter and both of my solar voltage regulators. I also have a 2000 watt inverter generator. So my question is? Why not leave every thing and just buy a stand alone solar generator for extra my power needs. If I had a stand alone solar generator I wouldn't need to use my noisy generator as much. I have found that using my CPAP machine at night, I can't keep up with my power needs with out using my generator.
Any comments?

 

[Johnnie-HILO]

Another potential problem. Removing the lithium batteries in the winter because lithium batteries don't like cold temperatures.

 

[JackandJanet]

Johnnie - Yes, converting to LiFePO4 batteries is not CHEAP, but, they're long life mitigates that issue somewhat, and, the longer discharge capacity is an additional plus. You should replace the converter in your trailer with one that charges Li batteries properly if you regularly use the converter when camping. I don't used the converter much, but my Elixir converter became too much trouble and I wanted something better. My replacement had the ability to charge Li batteries.

I DO use solar cells to keep the batteries charged when camping so I DID need to replace my solar controller. I am very happy with the Victron controller. The cell phone monitoring app is easy to use too.

The Victron DC-DC converter takes care of the charging problems between the batteries and the alternator when driving. It, and the Victron Solar Controller are basically "set and forget" devices.

I don't use the trailer in the winter and I store it with the batteries in a charged state. My lowest temps are about 15 degrees here, but I know your temps in Michigan are something below zero. I would not find it too difficult to remove the batteries if I was concerned about them in cold, but I know that's a subjective opinion.

I don't have any experience with a CPAP machine, but the LiFePO4 battery has about twice the useful capacity as an equivalent lead-acid battery. I also don't have any experience with solar generators, but my impression is that they would not carry you through the night either, due to their relatively small battery size.

Finally, I still take my Honda generator with me when camping. I learned that if camped in heavy shade, while the batteries DO get some charge from solar power, that it was not enough to keep up with my demands.

- Jack

 

[Johnnie-HILO]

Thanks for the reply. It looks like you crossed all the t's and dotted all of the i's. After reviewing all of the changes I would have to make to change over to lithium, I am leaning toward a solar generator for the extra needed capacity. Part of my problem, at my age (78), is I don't know how many years I will be able to camp. It's not a likely I would be getting my investment back when I sell. Also, with the portable power supply, I can keep and use for other purposes. If I was some what younger I think I would lean toward the lithium upgrade. Again, thanks for your very thought out perspective.

 

[Red Green]

Thanks for the write up Jack! I also have installed solar and LiFePO4 batteries in the last 2 campers I had. I believe the set up like you described is about the best way to go at it.

I do understand where Johnnie is coming from as well.

I haven’t thought much about converting my HiLo over yet, I think I will see if I survive the current project first. (Besides, if I switched gears and started focusing on a different project, my DW may decide I should just move into it right now! (And rightly so!)

But it was nice to read how you did it, and what you did. It helps by keeping the words and terminology (lingo) a little fresher in my mind. If I don’t keep up thinking about it, reading about it, soon I start to forget the little things, which seem to become the big things.

I used to think it was maybe old age, but now I think maybe my brain is so packed with all the decades, and decades, and decades of stuff, that it isn’t any wonder things randomly disappear! (Ok, maybe it is old age.) Ha!

 

[sam-HILO]

Lithium batteries.

Jack is a retired engineer and a good technical contributor to this forum.

 

[Red Green]

Yes, a wealth of information!