Lithium battery swap

[bleslie]

I am about to receive a new 24 32RLS,
The dealer only puts in a single lead acid group 24 battery. I am thinking or replacing the single lead acid battery with two lithium 100 amp batteries in parallel. My unit is stock and has a single, factory 320 watt solar on the roof. I have read about changing the setting on the controller to lithium.
Will I have any problems with towing or using either a Honda 2000 or a predator 3500 generator while boondocking? I sometimes will be with no shore power for up to two weeks at a time. Is there a fire hazard with lithium batteries?

Thanks

 

[Oregon_Camper]

you will have no issues with anything you've listed. One thing you do need to consider is adding a shunt. With Lithium batteries, you won;'t be able to determine proper charge levels with the the 4 LED. Here is the best shunt on the market...IMHO. You can save a few $$ and ge the verson without Bluetooth, but then you'll have to wire the display up..into the RV, so you can read it. The version with BT will allow you to access everyting from a Victron app.

Link to Victron BMV-712 shunt on Amazon

 

[darrell]

And here is the same thing without the display if you want to save a few dollars. It has bluetooth and mobile device apps, so the display may or may not be required.

 

[bleslie]

thanks to both of you. I will definitely install the shunt so I can see the state of discharge on new batteries

 

[Deanstephens62]

This is good info as I want to replace the lead acid with a lithium as well. I do have a question about the shunt though. If there is a Rover Li 20 Amp MPPT Solar Charge Controller on the 5th wheel what is the purpose of the recommended shunt? I want to be sure that I understand everything before swapping the battery. Does the charge controller not give the needed information for changing and discharging?

 

[Oregon_Camper]

This is good info as I want to replace the lead acid with a lithium as well. I do have a question about the shunt though. If there is a Rover Li 20 Amp MPPT Solar Charge Controller on the 5th wheel what is the purpose of the recommended shunt? I want to be sure that I understand everything before swapping the battery. Does the charge controller not give the needed information for changing and discharging?

Your solar controler will only report power coming into the RV from solar. If you're connected to shore power, the solar controller will not have access to that incoming power. A shunt will monitor all incoming (shore, solar, generator, dc-to-dc, etc...) power AND all power consumption. It will give you an actuate amp percentage, so you will always know the correct battery level.

 

[Deanstephens62]

Thanks for the details Jim. That makes a lot of sense and something that I need to keep in mind for the replacement.

 

[darrell]

Once you program the shunt, you will be able to see a rather accurate display of your battery SOC (state of charge) because it monitors everything in and out of the battery (including your solar if you install it right). So you can see how much solar you are producing on your SCC as a gross value, and the shunt will be able to tell you if you are charging or discharging (using more than solar is adding). It will tell you how much net power has actually flowed to and from the batteries. So if you have 200ah of battery, and the shunt has seen 40ah used, it knows you have 160ah (less the floor percentage - dependent on your battery but often around 10%) left. So usable, it will say 140ah left. It doesn't rely on the voltage as the measure as that is very difficult to do on LFP.

 

[daemonic3]

Alternatively, some batteries have the in/out current and SOC% available over BT built in. For example, I wanted to start with a group 24 battery in the same box so I got a Lion Energy 105Ah battery with BT capability. I think they only make group 24's, so it's the easiest drop in upgrade, but not as good for scaling into a battery bank.

 

[AMW]

How much should a good lithium battery cost?

 

[darrell]

How much should a good lithium battery cost?

Depends on size. LiTime are fairly well reviewed, as are SOK. Battleborns are popular but pretty spendy. Search Will Prowse videos on battery reviews on youtube, he is quite helpful.

 

[Gord&Cindy]

You may want to consider the charge line from your truck.
Depending on your truck configuration, you may need a DC to DC charge controller. I installed a 20 amp version to manage the current flow from the truck.

 

[daemonic3]

How much should a good lithium battery cost?

I'm fairly new to Li, but doing research in the fall here were some things I learned, experts feel free to correct me:

Seems like the cells themselves all come from China. The differences will all be in the 1) BMS (battery management system), 2) Packaging, and 3) Customer Service. The BMS is responsible for charge rates, evenly wearing the cells, output limits, etc. The better the BMS the more life and reliability you get out of the cells. The packaging will be how they package and wire the cells, the quality of the build, standard battery box shape vs custom shape, how much airflow they get, moisture proofing, (optional) heating elements, etc. The customer service should be obvious, but apparently some are non-existent, whereas a US based company with actual humans during business hours is super helpful.

Since it was my first time, I didn't want an inexpensive one. There are TONS for <$500. I figured I would go top of the line before risking the cheap ones. Battle Born, Lion, Tracker, Dakota all were expensive options ($500 to $1000), and I gravitated to the Lion due to the BT integration (plus the most A-h and lightest weight of any Group24). Lion was definitely not the cheapest, but was less than Battle Born. Their customer service was OUTSTANDING. I accidentally bought the non-BT version from Sportsman's warehouse before realizing the BT version is only available through Lion directly. Sportsman's does NOT allow battery returns, but Lion said they will take it back. Sent me a return packaging box, gave me the new one for 15% off, AND gave me a free portable power brick for my time and trouble + misunderstanding! All this over text messaging with fast responses. They also kept following up to make sure I was happy and satisfied.

Anyway, my battery is awesome, I love being able to watch the charge rate while driving or while in the RV using my phone. I can learn the draws of my DC loads (like the fridge), the 7-pin output, and the solar (separate BT app). You should be able to get the same thing using the add-on shunt, which is a separate purchase. I'll probably get a 2nd Lion group24 and a locking box on the tongue, and each will show up in the app individually.

 

[darrell]

You may want to consider the charge line from your truck.
Depending on your truck configuration, you may need a DC to DC charge controller. I installed a 20 amp version to manage the current flow from the truck.

IMO, it would be better money spent adding solar to the trailer over a DC-DC charger for the TV.

 

[Gord&Cindy]

IMO, it would be better money spent adding solar to the trailer over a DC-DC charger for the TV.

I would tend to agree, but you may still need to address the charge line. Either add the DC - DC charger to disconnect the charge line all together.

 

[darrell]

There is no reason to disconnect it. The charge they will get from the TV and the solar would be additive. There is nothing special about LFP batteries that would require you to disconnect the 12v+ from the 7-pin.

 

[Ben and Kathy]

IMO, it would be better money spent adding solar to the trailer over a DC-DC charger for the TV.

Friendly disagreement...

Benefits of a DC-DC converter:

• Prevents draw on TV batteries if TV is turned off
• Balances voltage between TV and trailer, 12v to 14v for lithium
• Provides a higher current feed from your TV electrical system to your trailer then is possible through the 7 pin 12v+
  • Especially important with lithium batteries, they charge at a much higher current rate then other types of batteries
• Cloudy day, night time travel, long travel day, inverter power draw (refrigerator, AC unit, etc) on trailer batteries could result in drained batteries; DC-DC prevents this by providing power from TV electrical system

If no solar, and you are going to run things that draws significant power from your batteries, you will need a DC-DC converter and a separate power circuit on your TV.

If solar, DC-DC will provide supplemental power to the solar and also offset power deficit if solar is not providing enough to keep up with the power demand of the trailer.

 

[darrell]

It all depends on your own situation.
1. My TV doesn't provide power when the ignition is off. Also, many modem trucks have a diode to prevent backfeeding from the trailer to the truck.
2. My truck can put out as much as 14.8v if needed and the alternator is controlled by the computer. I have 10g wire and a 30-anp fuse, so I can get power to the battery if needed.
3. Yes, you can get higher current, potentially, using a DC-DC charger. The key you are getting wrong here is that LFP will absorb what a charger can throw at it. It does not actually control anything about the charging process from the supply side though.
4. These can all be a problem during inclement weather or traveling at night.

However, this only really helps a ton when you are driving a lot, and even then, only when your destination doesn't have power available. Otherwise, your batteries need to only hold you from pole to pole if that is the type of camping you do. And a cold refrigerator and freezer will stay that way for long periods of time if you are not opening the doors. What else would really drain your batteries while traveling?

Case in point, I have a 45' fifth wheel, residential refrigerator, and a bunch of low power drawer electronics in my trailer that I run off the inverter. Between my solar and my 7-pin, I can get up to about 25 amps of power into the batteries when the sun is shining while driving. I use about 10-15 amps of power through the inverter on average when traveling. And that is with running everything including the fridge. I am still netting about 10-15 amps of charge through all of that.

In my case, a DC-DC charger would not buy me anything really. Worst case - I have a Onan 5500 LP generator on board.

All that to say, sure, for some use cases a DC-DC makes sense, but for many, imo, solar is a better investment. DC-DC doesn't help much when you are boondocking. However, my solar can run about anything I need (coffee is harder but doable with a stove top percolator we have from tent camping) as long as the sun is shining and will keep my batteries topped up. If not, my batteries can hold for a few days with careful usage of the fridge and cycling even with low levels of sunlight.

I have 3x190w PV on the roof,a 30a PWM SCC, a 1500w pure sine inverter, and 2x100ah of LFP. I monitor usage with a Victron SmartShunt. My solar package was provided by the manufacturer and is GoPower oem equipment.

 

[bleslie]

some of my boondocking and winter storage will have temps in the mid 20s
with lithium will i need units with built in battery heaters
any thoughts on two 100 in parallel versus a single 200 unit i have two gen sets so charging is not a problem
thanks

 

[Oregon_Camper]

some of my boondocking and winter storage will have temps in the mid 20s
with lithium will i need units with built in battery heaters
any thoughts on two 100 in parallel versus a single 200 unit i have two gen sets so charging is not a problem
thanks

Add up amp output. Some 100's will do 100 amp each, so 200 total. See what the 200Ah (single unit) can output.