Camper LiFePo4 conversion charging options

[stewchi]

I am weekend camper and looking to increase battery AH to last 3+ days without needing the generator, which looks like ~300AH LiFePo4. My current setup in the camper is 2 12V 100AH FLA batteries (5 years old), single stage 55A converter (currently reading 13.72V at the battery), 1000W pure sine inverter, 2500W generator. I would like to rapid charge with the generator to decrease how long I make noise with it (when batteries are low). Most of the time the camper is "stored" in my yard with full hookups and used as an extension to the house (second office, pool house etc). So I need to be able to leave shore power plugged in for months at a time and not worry about the batteries but also be able to charge rapidly with a generator. This also means the camper will always leave the house on a full charge
Should I:
- Upgrade the converter to a lithium friendly converter
- Ditch the converter and add a charger like the Victron IP22 (only 30A compared to my current 55A setup)
- Add a DC to DC 12v - 12v converter with the input being from my single stage converter that I can program output for my batteries?
I am willing to pay a premium for things to just work that do not require manual intervention or constant tuning or maintenance
I really like the software interface options (Like the Victron platform)
Solar is a likely add on down the road for me (camper is pre wired with 10awg at the roof and hitch)
I am an Electrical Engineer and avid DIYer who likes to build stuff (but not maintain it LOL)
Future LiFePo4 battery location is ~5ft from the existing converter (inside the DC distribution panel) with existing 4awg wire. (its a straight pull if I need to swap it to bigger)
I look forward to everyone's thoughts

 

[HRTKD]

I understand your goal. I would rather be camping than watching dials, flipping switches and swapping cables. I designed my system so my wife could be by herself all day in the trailer without having to worry about power or following complicated instructions or any instructions for that matter.

I have 560 Ah of LiFePO4 battery with 640 watts of solar. I rarely run my generator to charge my battery bank. Only on extremely cold nights (< 10° F) will I run the generator for that. Otherwise, I run the generator to run the microwave. I have a small inverter that isn't big enough to run the microwave. The rest of the system could handle it though.

Your connection to shore power all the time presents a minor issue. You don't want to keep LiFePO4 batteries on a charger all the time. If you do, you would want an alternate charge profile that uses lower voltages.

You can stack chargers/converters to get more amps into the battery faster, within the charging limits of the battery.

I did change to a converter with a LiFePO4 charge profile. I do not use alternator charging for my LiFePO4. I disconnected that circuit. Maybe someday I'll put in a DC-DC charger to work with that. But for now, I have no need for a charge from the alternator.

Victron has a great landscape. I don't think any other vendor has anything close. Victron is quality gear. There are very few problems seen here on the forum with Victron.

 

[stewchi]

I am leaning towards adding the IP22 Victron 30A charger as the main shore power charger. Then adding a switch (disconnect) on my 55A converter that will only be on when I need to bulk charge the battery quickly (IE on generator power), think of it like a turbo button. It would be manual but if I am hooking up the generator I don't mind flipping on the converter too. I am not sure how much current will pull on the converter since the voltage is only 13.8, plus I will have to mess with the charge profile of the IP22 to keep it in bulk mode until the battery get up to 90% or so. Anything wrong with this approach?
What I have learned so far is none of the RV converters are designed for LiFePo4. The Power Dynamics and the PM3s use a dumb timer based system for bulk charge then lower float. The iota appears to somehow sense the voltage (or current changes) but then put it on float then 15 days later switch back to bulk which is totally unnecessary for LiFePo4 from what I read and could potentially put a fully charged battery into bulk charge.
I think with the IP22, BMV 712 I should be able to program something that charges up the battery when we return from our trip then leaves it on a very low float that is too low to charge but would power the DC loads while on shore power in the yard. I believe the IP22 will allow me to turn it off form the phone app giving me the option to not charge while plugged into shore power.
Also in another post somewhere I saw someone ask if you could just use the solar charge controller and plug the converter output into the solar charger input. It appears that wont work. The Victron had a footnote that said the input voltage had to be 5V more than the output voltage for the solar charge controller. Maybe someone who has one can validate seemed odd to me.

 

[Zwy]

I am weekend camper and looking to increase battery AH to last 3+ days without needing the generator, which looks like ~300AH LiFePo4. My current setup in the camper is 2 12V 100AH FLA batteries (5 years old), single stage 55A converter (currently reading 13.72V at the battery), 1000W pure sine inverter, 2500W generator. I would like to rapid charge with the generator to decrease how long I make noise with it (when batteries are low). Most of the time the camper is "stored" in my yard with full hookups and used as an extension to the house (second office, pool house etc). So I need to be able to leave shore power plugged in for months at a time and not worry about the batteries but also be able to charge rapidly with a generator. This also means the camper will always leave the house on a full charge
Should I:
- Upgrade the converter to a lithium friendly converter
- Ditch the converter and add a charger like the Victron IP22 (only 30A compared to my current 55A setup)
- Add a DC to DC 12v - 12v converter with the input being from my single stage converter that I can program output for my batteries?
I am willing to pay a premium for things to just work that do not require manual intervention or constant tuning or maintenance
I really like the software interface options (Like the Victron platform)
Solar is a likely add on down the road for me (camper is pre wired with 10awg at the roof and hitch)
I am an Electrical Engineer and avid DIYer who likes to build stuff (but not maintain it LOL)
Future LiFePo4 battery location is ~5ft from the existing converter (inside the DC distribution panel) with existing 4awg wire. (its a straight pull if I need to swap it to bigger)
I look forward to everyone's thoughts

If you're looking to last 3+ days without the generator (except to run air conditioning), then adding a few panels might actually work out best. Portable or permanent mounted, permanent preferred if you don't want hassle. Panels are cheap, not hard to install.

As this would be connected to shore power most of the time, the Victron 30a would be more than sufficient or I would swap out the converter.

If house batteries are currently connected to alternator, then yes, you should add a DC to DC. Some DC to DC also include an MPPT charger, this might be a great option for you. I'm currently looking at Kisae.

I see Kisae introduced this: https://www.kisaepower.com/bic-launch/

I wish that had been around before I purchased a Growatt.

 

[JimOK]

Not sure how much you know about LiFePO4 batteries. This is lengthy, but worth knowing since LiFePO4 batteries are so expensive.
They have specific operating parameters that need to be observed to get the most life from them.
They have a minimum and maximum operating voltage range. When the get outside this range, they die. 10 volts is the absolute minimum. For longer life, keep them above 12 volts. 14.6 volts is the absolute maximum voltage. For longer life, keep them below 13.6 volts.
They have a minimum and maximum operating temperatures.
The battery loves 77 degF. Do not charge the battery when it is below 32 degF. It will die. Do not discharge the battery when it is below 20 degF. The battery does not like high temperatures. High temperatures will kill the battery. Try to limit the maximum battery temperature to 90 degF.
The LiFePO4 battery does not like storage at full charge. Try to keep the battery between 50% and 60% charge when storing for long periods of time. A LiFePO4 battery can be stored up to a year at 60% charge. They have a very slow self discharge rate. Just disconnect the battery when storing. They can re-charge at a lot faster rate than a lead acid battery. Just connect the battery and turn on shore power few a few hours to top it off.
The absolute worst thing to do to a LiFePO4 battery is to store it at full charge in high temperatures.
Hope this helps.
Happy camping.

 

[stewchi]

Not sure how much you know about LiFePO4 batteries. This is lengthy, but worth knowing since LiFePO4 batteries are so expensive.
They have specific operating parameters that need to be observed to get the most life from them.
They have a minimum and maximum operating voltage range. When the get outside this range, they die. 10 volts is the absolute minimum. For longer life, keep them above 12 volts. 14.6 volts is the absolute maximum voltage. For longer life, keep them below 13.6 volts.
They have a minimum and maximum operating temperatures.
The battery loves 77 degF. Do not charge the battery when it is below 32 degF. It will die. Do not discharge the battery when it is below 20 degF. The battery does not like high temperatures. High temperatures will kill the battery. Try to limit the maximum battery temperature to 90 degF.
The LiFePO4 battery does not like storage at full charge. Try to keep the battery between 50% and 60% charge when storing for long periods of time. A LiFePO4 battery can be stored up to a year at 60% charge. They have a very slow self discharge rate. Just disconnect the battery when storing. They can re-charge at a lot faster rate than a lead acid battery. Just connect the battery and turn on shore power few a few hours to top it off.
The absolute worst thing to do to a LiFePO4 battery is to store it at full charge in high temperatures.
Hope this helps.
Happy camping.

Thanks Jim, I have been researching a lot. My camper is nearly never "stored" but it may go a week or so without active use. By that I mean its like a guest room in the yard. I have it on full hookups when at home, AC is running set to keep the camper below 85. Battery and controllers will be inside for the reasons you stated. That will be the state 90% of the time. We are taking it out in July for the full month mostly boondocking but staying where they have hookups when we can get a reservation. Otherwise it is weekend trips. As @Zwy points out it may be better or needed in addition to get some panels. Our camping is mostly sightseeing and the camp site is home base so there are lots of times no one is home making portable panels a little risky but roof top is a good option. My FLAs starting to degrade so I need batteries anyway and would hate to throw $300 more at FLA, but maybe I should to buy some time while I figure out what I want.

 

[Just An RVer]

My FLAs starting to degrade so I need batteries anyway and would hate to throw $300 more at FLA, but maybe I should to buy some time while I figure out what I want.

I'm right there with you, only my batteries are still in good shape. If it was just a matter of purchasing a set of LiFePO4's that would be one thing. But I just couldn't swing the batteries, a new converter, and DC-DC charging all at once.

If you do end up kicking the LiFePO4 can down the road, try to make sure any upgrades you make in the meantime will also work with your lithium batteries in the future. Virtually every solar charge controller I've seen lately would work with your FLAs now and could be reprogrammed for lithium.

I wouldn't want to charge lithium batteries with a converter made for lead-acid. Another option for fast charging from shore power/generator would be an inverter-charger with high amperage charging. The Victron ones I've seen charge at up to 80 amps for the 1800w and 120 amps for the 2400w. From what I can tell, there's a knob on the remote panel to adjust the max charging current.

Theoretically, you could change the charge profile for most smart chargers and some solar charge controllers for deeper charge/discharge cycles while you were on a trip and when you get home switch back to more conservative settings to prolong the battery life, but I don't have the experience to say which, if any, vendor that automates that enough to be practical for those of us who don't want to monkey around with the settings for individual devices.

 

[stewchi]

I am officially obsessed, I designed the system I want which includes LiFePos, roof and portable solar etc adds up to about $4k. If I stick with FLA batteries it cuts out a number of accessories and drops the cost to about $2500. Which us about how much it would be if I skipped the solar and only did the battery upgrade. Some items like the EMS and BMV-712, disconnects etc are needed for either.
When / if I pull the trigger I will post my build progress.

 

[HRTKD]

LiFePO4 has a fairly steep upfront cost. But the battery life should exceed lead acid. If you have to buy lead acid batteries two or three times when in the same time frame only one set of LiFePO4 batteries are purchased, the number for LiFePO4 look a lot better.

 

[Mittmy]

I want to swap from my FLA battery in my pickup camper to a LiFePO4. It would work great for all the normal loads of lights and fans. But I also need to start my onboard generator with the camper battery. The 3400 W generator is rated for 250 cranking amps. But actually only pulls about 50 a when starting. Has anyone had experience in using the 12v 100ah LiFePO4 battery for a camper with a generator to start also? Several of the 12v 100ah batteries are rated for 100a continuous output and 200a 5 sec burst output. Would this work?

 

[HRTKD]

There is a forum member that has a bigger generator than yours and he measured a surge in excess of 200 amps. He has a bigger battery than yours, probably 280 Ah with a 120 amp BMS. It worked to start his generator.

I retained a small lead acid battery to start my generator. I wasn't comfortable with a 200+ amp surge even though my LiFePO4 battery bank should be able to handle it. I have two 4s 280 Ah batteries, each with a 120 amp BMS.

 

[time2roll]

I am leaning towards adding the IP22 Victron 30A charger as the main shore power charger. Then adding a switch (disconnect) on my 55A converter that will only be on when I need to bulk charge the battery quickly (IE on generator power), think of it like a turbo button. It would be manual but if I am hooking up the generator I don't mind flipping on the converter too. I am not sure how much current will pull on the converter since the voltage is only 13.8, plus I will have to mess with the charge profile of the IP22 to keep it in bulk mode until the battery get up to 90% or so. Anything wrong with this approach?

Nothing inherently wrong with it. I plan to go a different direction and cut power to the converter when the set voltage is reached. Then the converter is off and I would run on battery power until the low voltage was reached.

I plan to use this or something similar to cut 120v power to the converter.

https://www.ebay.com/itm/191818637112?hash=item2ca9481f38:g:a4IAAOSw3gJZI~yO

Should fit right in the distribution panel. No second charger is needed. A true charge and off cycle vs float/storage etc.

 

[stewchi]

Nothing inherently wrong with it. I plan to go a different direction and cut power to the converter when the set voltage is reached. Then the converter is off and I would run on battery power until the low voltage was reached.

I plan to use this or something similar to cut 120v power to the converter.

https://www.ebay.com/itm/191818637112?hash=item2ca9481f38:g:a4IAAOSw3gJZI~yO

Should fit right in the distribution panel. No second charger is needed. A true charge and off cycle vs float/storage etc.

Unfortunately my converter is a fixed 13.8V so I don't think I could ever get the batteries fully charged in a reasonable time.

 

[Stupid Monkey]

I've an IP22 and 30A from the generator is slow (500w use of a 2.7kw generator in my case) so I bought a Victron Multiplus inverter charger, 80A of charging - great settings within the box to tell it its connected to a generator rather than grid, select maximum current the genny can give and a slow ramp-up on power use.

Top bit of kit, and with the 30A IP22 and the inverter/charger I can get over 100A of fast charge on the generator in winter and with great load balancing say if I run the genny while I have other large load going (dishwasher, washing machine or oven) charge will boost when the load is low and then reduce when the power need diverting to load. Really well designed for real world use.