Swithcing to Li-ion, please help me be lazy

[JeffKim]

Originally Posted by smithcreek

Wow, thanks for all the replies! I see some of you have/had very similar goals to mine. I just don't want to be on a three day camping/travel trip worrying about trying to find the spot of sunlight in the densely forested northeast state park campground, then follow it around all day or else run out of juice for the propane fridge!

I ordered the Epoch 300Ah battery with heater and bluetooth, the Epoch 50amp charger and the Epoch battery tray in case I end up moving it under the bed in front.

I'm skeptical of the charger (see above), but sounds like a good choice. Can you post how it goes and take some pictures? Always useful for anyone following in your footsteps. Thanks.

Our 4x100Ah batteries are inside under a twin bed. Freeing up the battery compartment and having the batteries sheltered is nice. The Epoch Essential is IP54, so not very waterproof. I pulled the battery cable through and shortened it. You will need to crimp on battery lugs.

[smithcreek]

Originally Posted by JeffKim

Can you post how it goes and take some pictures? Always useful for anyone following in your footsteps. Thanks.

I will do that. I moved to VT in '21 and have not had the trailer off my property since then. I built a garage with a carport and lived in the trailer for over 2 years both inside the garage and outside under the carport, while doing all the interior work on the shell of a house I had built. I moved out of the trailer and into the house about a year ago.

In a couple weeks I am taking a shakedown trip to visit friends back in RI, about 3 hours south of me. With new tires and new batteries I'm hoping to be good to go for a few years. I've got some longer trips planned for this summer and can't wait to get back on the road!

For now the plan is to put the battery wherever I have time to put it. I'm hoping to get it under the bed, but if I don't have time and the wiring gets difficult it's going in the battery box.

[Bill M.]

Are you going to re-cable the batteries with a buss bar?

[uncle_bob]

Originally Posted by Bill M.

Are you going to re-cable the batteries with a buss bar?

Hi

There's been more than a few twists and turns. Aren't we talking about a single 300AH battery? If not, I could have easily missed that turn in the road.

I'd measure *your* battery(s) and *your* battery box. If things *might* go in there that's going to be needed data. The battery boxes on AS trailers do vary a bit. Even the batteries get minor tweaks from time to time.

You may have plenty of room for all sorts of stuff in there. It's also possible you just might not have much room at all .....

Fun !!!

Bob

[TJBus]

I haven't had a chance to read through all of the responses, but I also want to upgrade to lithium.

[marynya]

LiFePO4 batteries with a built-in battery management system (BMS) are generally compatible with lead-acid batteries. They have a nominal output of 12.8 volts while the BMS handles the charge cycle and also provides a number of protective functions. They will generally work with any charger set up for AGM batteries but you should check the specs carefully. The LiTimes 100AH batteries I have (two in parallel) require a charge voltage between 14.2 and 14.6 volts and a float voltage of 13.4 or more. They don't talk about float voltage in the literature because the battery itself does not need it. You can leave it at 14.4 indefinitely and the BMS prevents overcharging. If your charger has a float mode to handle 12 volt loads, it needs to be at least 13.4 volts to prevent some discharge of the battery with 12 volt loads in operation. My inverter has a powerful charger built into it with selectable profiles for various types of lead-acid batteries. It has two profiles for AGM types and one is just what the BMS requires. The other is usable but the float voltage is a bit low.


These batteries are available with a Bluetooth interface to a phone app which will give you the state of the battery. I had an inexpensive battery monitor which worked well enough so I didn't buy that feature. You can't tell much about the battery state from the voltage so you need a monitor which can sense the current going into and out of the battery and total it up to give you an estimated charge level.


One thing I don't know about is the reliability of the BMS electronics. It is possible that the BMS might fail before the battery does and they do not seem to be replaceable. It might be safer in the long run to buy batteries without the BMS and get a charger intended for this type of battery. For use with an existing system that is satisfactory, the BMS makes good sense.


LiFePO4 batteries will maintain their nominal 12.8 volts until almost completely discharged and then draw the maximum output of the charger until they are almost completely charged giving you longer run times and shorter charge times than lead-acid batteries.

[RMNummi]

WFCO WF-5110R is the inverter on my 20 25FBT. It’s a 1k Inverter. My preliminary research has provided a couple of options….
1. WFCO makes a 2k version.
2. I shot myself in the foot by ordering a Victron Phoenix to “swap”… immediately noticed the OEM WFCO 1k is a “smart” inverter.. it auto switches to shore power when it senses same. Phoenix is a “”dumb” inverter suitable only for those older ASs that have dedicated Inverter outlets.

[gypsydad]

Originally Posted by marynya

LiFePO4 batteries with a built-in battery management system (BMS) are generally compatible with lead-acid batteries. They have a nominal output of 12.8 volts while the BMS handles the charge cycle and also provides a number of protective functions. They will generally work with any charger set up for AGM batteries but you should check the specs carefully. The LiTimes 100AH batteries I have (two in parallel) require a charge voltage between 14.2 and 14.6 volts and a float voltage of 13.4 or more. They don't talk about float voltage in the literature because the battery itself does not need it. You can leave it at 14.4 indefinitely and the BMS prevents overcharging. If your charger has a float mode to handle 12 volt loads, it needs to be at least 13.4 volts to prevent some discharge of the battery with 12 volt loads in operation. My inverter has a powerful charger built into it with selectable profiles for various types of lead-acid batteries. It has two profiles for AGM types and one is just what the BMS requires. The other is usable but the float voltage is a bit low.


These batteries are available with a Bluetooth interface to a phone app which will give you the state of the battery. I had an inexpensive battery monitor which worked well enough so I didn't buy that feature. You can't tell much about the battery state from the voltage so you need a monitor which can sense the current going into and out of the battery and total it up to give you an estimated charge level.


One thing I don't know about is the reliability of the BMS electronics. It is possible that the BMS might fail before the battery does and they do not seem to be replaceable. It might be safer in the long run to buy batteries without the BMS and get a charger intended for this type of battery. For use with an existing system that is satisfactory, the BMS makes good sense.


LiFePO4 batteries will maintain their nominal 12.8 volts until almost completely discharged and then draw the maximum output of the charger until they are almost completely charged giving you longer run times and shorter charge times than lead-acid batteries.

My LiTime Group24 12V batteries are now 9 months old and doing well, I think. I did install a new Boondocker converter that is for Lithium. If doing it again, I would have selected a Progressive Dynamics model, but mine works well. It does charge at 14.6 but batteries show 13.4 when full typically, and converter is not charging. The built in Bluetooth BMS shows state of charge, status, voltage, equalization, and is very convenient. I recently went on a week long trip, after returning, I tuned into the BMS and noted one battery showed 88%; the other showed 100%. Plugged into shore power over night, and next day both showed 100%. Wondering if I need to rewire the connections using the (+/-) buss bar's mounted to the battery box to better balance the loads?

[uncle_bob]

Originally Posted by RMNummi

WFCO WF-5110R is the inverter on my 20 25FBT. It’s a 1k Inverter. My preliminary research has provided a couple of options….
1. WFCO makes a 2k version.
2. I shot myself in the foot by ordering a Victron Phoenix to “swap”… immediately noticed the OEM WFCO 1k is a “smart” inverter.. it auto switches to shore power when it senses same. Phoenix is a “”dumb” inverter suitable only for those older ASs that have dedicated Inverter outlets.

Hi

If you are playing with an inverter as well, the answer is pretty simple:

Get a device that is *both* an inverter and a converter / charger. Victron calls them Multiplus devices. They come in several sizes. Xantrex also makes pretty good ones for a bit less money.

You want to get one with a remote display panel (often an add on option). Some do (and some do not) come with Bluetooth. If possible, get the Bluetooth version.

Bob

[marynya]

Originally Posted by gypsydad

My LiTime Group24 12V batteries are now 9 months old and doing well, I think. I did install a new Boondocker converter that is for Lithium. If doing it again, I would have selected a Progressive Dynamics model, but mine works well. It does charge at 14.6 but batteries show 13.4 when full typically, and converter is not charging. The built in Bluetooth BMS shows state of charge, status, voltage, equalization, and is very convenient. I recently went on a week long trip, after returning, I tuned into the BMS and noted one battery showed 88%; the other showed 100%. Plugged into shore power over night, and next day both showed 100%. Wondering if I need to rewire the connections using the (+/-) buss bar's mounted to the battery box to better balance the loads?

Bus bars are a good idea with parallel batteries but heavy-gauge jumpers should work fine so long as the connections are good. The main problem is that you end up with two or three connectors on one battery terminal which is not so good if there is any chance of corrosion, such as with an external battery box intended for flooded-cell batteries. If the batteries are inside or in a protected box, that should not be a problem with Li-ion batteries which do not contain corrosive acid.


If you are cycling batteries, they should be charged to 100% periodically. The cells are never quite identical and will accumulate different charge levels over multiple cycles unless charged to 100% occasionally. That is what "equalization" is all about.


Note that Li-ion batteries have a greater fire risk than lead-acid batteries but the LiFePO4 type is considered to be much safer than other types and the BMS circuits are designed to protect the battery from overheating.

[gypsydad]

Originally Posted by marynya

Bus bars are a good idea with parallel batteries but heavy-gauge jumpers should work fine so long as the connections are good. The main problem is that you end up with two or three connectors on one battery terminal which is not so good if there is any chance of corrosion, such as with an external battery box intended for flooded-cell batteries. If the batteries are inside or in a protected box, that should not be a problem with Li-ion batteries which do not contain corrosive acid.


If you are cycling batteries, they should be charged to 100% periodically. The cells are never quite identical and will accumulate different charge levels over multiple cycles unless charged to 100% occasionally. That is what "equalization" is all about.


Note that Li-ion batteries have a greater fire risk than lead-acid batteries but the LiFePO4 type is considered to be much safer than other types and the BMS circuits are designed to protect the battery from overheating.

Thanks for that. Makes sense from what I am seeing. I do flip manual switch when storing after a night charging. Went back after returning from our trip and charging overnight at storage, and both were 100%. They are LiPO4, Group 24 with bluetooth BMS from LiTime. So far, no issues.

[uncle_bob]

Hi

The argument *against* bus bars is shock and vibration. Yes, this is assuming you mount the bus bars directly to the batteries. That may or may not be what is being done by this or that person.

Your batteries will never be totally stable, no matter how you try to mount them. As they move around, the terminals get closer or further apart. It may be a pretty tiny amount, it's still motion.

A bus bar is a very rigid thing. When the battery tries to move, it "holds" the terminal in place. It's a really good bet the terminal is designed for electrical connection and not as a strong mounting point.

A jumper (even a beefy one) provides some amount of flex. This gets the terminal on the battery out of the equation.

In a stationary setup (solar in your home) there really is no issue like this. In an RV blasting down that rock strewn road at high speed there most certainly is an issue.

Bob

[gypsydad]

Originally Posted by uncle_bob

Hi

The argument *against* bus bars is shock and vibration. Yes, this is assuming you mount the bus bars directly to the batteries. That may or may not be what is being done by this or that person.

Your batteries will never be totally stable, no matter how you try to mount them. As they move around, the terminals get closer or further apart. It may be a pretty tiny amount, it's still motion.

A bus bar is a very rigid thing. When the battery tries to move, it "holds" the terminal in place. It's a really good bet the terminal is designed for electrical connection and not as a strong mounting point.

A jumper (even a beefy one) provides some amount of flex. This gets the terminal on the battery out of the equation.

In a stationary setup (solar in your home) there really is no issue like this. In an RV blasting down that rock strewn road at high speed there most certainly is an issue.

Bob

Good input UB, but I am able to use the existing battery screw/wing nut threaded rod tie down that came with the AS in the battery box, since I have 2, 100AH Group 24 LiTime batteries. I would like to have known/gotten the Epoch 300AH, but I'm finding these 2 batteries are actually proving to work pretty good for our use model; never have run down below 50% even after a week of normal use. (always carry the Honda 2200 if needed!

[JDN31PDX]

We bought an Epoch 300 during their Black Friday sale. Then we got lost is all the opinions on what else we needed to do to make it work.

We finally took the trailer in for service two days ago and asked the guy if he installed lithium batteries. YES. he changed the converter to one compatible with lithium and installed a self resetting fuse that trips if the battery tries to draw too much power from the truck’s alternator. That was it. We can monitor the battery over Bluetooth with Epoch’s app.

Good luck on your install!

[smithcreek]

I got the battery, charger and mounting plate earlier this week and put it aside until the weekend to install it. Got it done this afternoon. I went as simple as I could. I cut off the terminal connectors and pulled the battery cables into the trailer under the front bed. Cut the cable to length and crimpled and soldered new terminal connectors on. Screwed the mounting plate down, strapped the battery down and attached the cables.

At the converter/panel end I removed the old converter. I used the breaker the old converter was hooked up to to install an outlet box and outlet. Cut the terminal cables off the cable that came with the battery and hooked it up to the 12v panel.

The most difficult part was cutting the first inch off the face of the old converter box since that is what the access panel/cover mounts to. Once I cut it I installed it back where it was originally and mounted to cover.

All it all it took 5-6 hours and half of that was head scratching. If I had a plan I knew would work going in it would have taken 3-4 hours. All done and ready for my first trip this Thursday. I'll be on the road for 3 nights, leaving on Thursday afternoon and returning Sunday. A good shakedown run for the new tires and battery system. Thanks to everyone for the advice on what to get and how to install it!

[PeteC17]

I am converting my FLA batteries to 2 100 Ah Lifepo batteries. Although I would prefer to mount them inside the trailer, for various reasons, I am leaving them in the battery box for now. I intend to use 2 bus bars for positive and negative connections. I also installing a Blue Sea battery disconnect switch. I have the stock 1000w inverter, stock WFCO AD converter (hoping that will correctly sense the Li batteries!) and 300 watts of solar. I am going to use a MRBF fuse on the positive battery terminal. I am using 2AWG cable from the battery to the positive bus bar. I am thinking that 200 amp MRBF fuse should protect the short run of 2AWG cable to bus bar, with the disconnect in line between the bus bar and the MRBF fuse block. Am I in the ball park with 200 amp fuse, or would 150 suffice? As near as I can figure, the inverter (infrequently used, so far) should be the biggest draw at about 90 amps, with normal trailer dc usage maxing out at about 50 amps? Appreciate any feedback.
Thanks,
Pete
2023 Flying Cloud 25 RBT

[richard5933]

Originally Posted by PeteC17

I am converting my FLA batteries to 2 100 Ah Lifepo batteries. Although I would prefer to mount them inside the trailer, for various reasons, I am leaving them in the battery box for now. I intend to use 2 bus bars for positive and negative connections. I also installing a Blue Sea battery disconnect switch. I have the stock 1000w inverter, stock WFCO AD converter (hoping that will correctly sense the Li batteries!) and 300 watts of solar. I am going to use a MRBF fuse on the positive battery terminal. I am using 2AWG cable from the battery to the positive bus bar. I am thinking that 200 amp MRBF fuse should protect the short run of 2AWG cable to bus bar, with the disconnect in line between the bus bar and the MRBF fuse block. Am I in the ball park with 200 amp fuse, or would 150 suffice? As near as I can figure, the inverter (infrequently used, so far) should be the biggest draw at about 90 amps, with normal trailer dc usage maxing out at about 50 amps? Appreciate any feedback.
Thanks,
Pete
2023 Flying Cloud 25 RBT

Fuses protect the wiring, not the devices. You're trying to prevent running more current over your cables than they can safely carry.

If you have an expected load higher than the cables can carry, the solution is to use larger cables, not adjust the fuse.

So, figure out your largest anticipated current draw, size the wiring appropriately, and then use a quick-blow fuse that will protect the wiring.

[DCPAS]

Originally Posted by PeteC17

I am converting my FLA batteries to 2 100 Ah Lifepo batteries. Although I would prefer to mount them inside the trailer, for various reasons, I am leaving them in the battery box for now. I intend to use 2 bus bars for positive and negative connections. I also installing a Blue Sea battery disconnect switch. I have the stock 1000w inverter, stock WFCO AD converter (hoping that will correctly sense the Li batteries!) and 300 watts of solar. I am going to use a MRBF fuse on the positive battery terminal. I am using 2AWG cable from the battery to the positive bus bar. I am thinking that 200 amp MRBF fuse should protect the short run of 2AWG cable to bus bar, with the disconnect in line between the bus bar and the MRBF fuse block. Am I in the ball park with 200 amp fuse, or would 150 suffice? As near as I can figure, the inverter (infrequently used, so far) should be the biggest draw at about 90 amps, with normal trailer dc usage maxing out at about 50 amps? Appreciate any feedback.
Thanks,
Pete
2023 Flying Cloud 25 RBT

I have a similar setup but without the solar. I also have the batteries in the box and OEM wiring to the interior. I had one OEM 100 amp MRBF fuse on the positive terminal of the series connected lead acids. I reused it on one battery on its positive terminal to the bus bar cable and bought another 100 amp fuse for the other battery positive terminal to the bus bar. Given that my wiring was OEM sized and they used a 100 amp fuse, I thought it best to stay at that level.

As an aside, we got very little use of the inverter with the lead acid batteries. Now we use it a lot. Great improvement.

[marynya]

Originally Posted by PeteC17

I have the stock 1000w inverter, stock WFCO AD converter (hoping that will correctly sense the Li batteries!) and 300 watts of solar.
2023 Flying Cloud 25 RBT

You need to check the spec or measure the converter output voltage when charging. The outside battery box means that it was set up for flooded batteries which must be charged at 13.8 volts. LiFePO4 batteries require around 14.4 volts to charge properly, as do AGM batteries. It is very unlikely that it can sense the battery type. It may have a switch that can be set to different battery types, in which case you need an AGM setting.

[uncle_bob]

Hi

There's a bit more to this ....

The wires have some amount of current they can carry before they catch fire. There are tables out there that will give you this information. You will need to know the type of wire (copper or aluminum) and the temperature rating. There is a rating for the jacket material on the wire. You also need to be aware of the temperature limits on anything the wire might ago by.

Next up is the voltage drop on the wire. In a 12V system you can easily set up cables that don't catch fire, but have way more drop under load that they should have. Starting with 12V at the battery and getting 8V at (say) the inverter is not going to make the inverter happy. Again there are tables that will give you the ohms per foot for this or that size wire. Voltage drop in ohms times amps. You get drop from both the hot wire and from the ground wire.

Fuses are rated not just for current, but also for time. Since they protect wire, heat takes a while to build up. More current for a very short while may not overheat the wire. Something like an inverter just might pull a big chunk of current for a short while. Ideally the fuse, wire temperature, and wire voltage drop would be ok with this.

Next up, a lot of folks have lithium batteries these days. The BMS in the battery (hopefully) will not allow massive current to be pulled. Like the fuse, this probably is a "how much for how long" sort of number. You might get 100A long term and 200A short term.

How well batteries in parallel deal with big loads is very much a "that depends" sort of thing. Does one battery supply most of the load? It just might ( more likely if there are odd things done when wiring them up ...).

Fuses are much slower than a BMS. A 201A overland might well cause a BMS to shut down. A 100A fuse likely will pass that 201A and not even blink at it. Once the BMS shuts down who knows how it gets started up again ( = this very much depends on which BMS in what brand battery ...). The answer here is not fuse stuff, it's not putting to big a surge load on the battery bank.

.... and this all seemed so easy

Bob