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01-31-2022, 01:17 PM
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#1
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Member
Join Date: Jul 2021
Posts: 40
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How to find out if RV can use lithium battery?
I have a 2015 crossroads zinger 26bt. I'm wanting to put in a lithium battery/batteries. But I'm reading you can't just swap and call it good. If the charger isn't compatible I'll just be throwing money away. So how/where do I check if my charger will work with a lithium (lifepo4) battery? Any info helps.
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01-31-2022, 01:55 PM
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#2
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Senior Member
Join Date: May 2018
Posts: 890
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Lots of issues
It definitely tends to be more of a project then a direct swap.
The first question is can your inverter/charger be programmed for Lifepo4. If not it won't be ideal, but some people roll that way and it works. One of the advantages of Lifepo4 is it can be charged more quickly, so you may want to get an additional charger which can greatly reduce generator run time.
Another issue is that Lifepo4 batteries in some cases draw too much current from your alternator when the Lifepo4 is at a low state of charge. One option is to just check the current draw and if your current draw is less then 25% of your alternator output then it shouldn't burn up your alternator. But also realize that an alternator won't be able to fully charge the batteries because the voltage is too low. You can disable your merge relay and get a DC to DC battery charger to get around these 2 issues.
Lifepo4 batteries will be destroyed if you charge them bellow 32°f, so you want one that has low temperature charge protection and you probably want to put them in a place you can keep from freezing.
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01-31-2022, 03:36 PM
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#3
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Senior Member
Join Date: Sep 2016
Location: Sarasota, FL
Posts: 5,228
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Quote:
Originally Posted by Torchic
I have a 2015 crossroads zinger 26bt. I'm wanting to put in a lithium battery/batteries. But I'm reading you can't just swap and call it good. If the charger isn't compatible I'll just be throwing money away. So how/where do I check if my charger will work with a lithium (lifepo4) battery? Any info helps.
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I think you answered your own question - check with the charger Mfr. If you don't know how your battery bank(s) are charged - that is a different question, one that needs to be answered first.
__________________
Rick and Larrie Dee
1997 40' Newmar London Aire DP CTA 8.3 (Mechanical) 325 Spartan MM
Bringing her back to her glory.
'08 Jeep GC Overland.
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02-05-2022, 12:09 PM
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#4
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Senior Member
Join Date: Jun 2016
Location: SW Louisiana
Posts: 8,939
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If you tell us the brand and model of converter you have, we might be able to help
__________________
2002 Safari Trek 2830 on P32 Chassis with 8.1L w/ 400 watts solar 420Ah LiFePo4
2017 Jeep Cherokee Overland & 2007 Toyota Yaris TOADs with Even Brake,
Demco Commander tow bar and Blue Ox / Roadmaster base plates
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02-05-2022, 02:13 PM
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#5
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Senior Member
Join Date: Jul 2017
Location: Michigan
Posts: 1,010
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Quote:
Originally Posted by dssl
Lifepo4 batteries will be destroyed if you charge them bellow 32°f, so you want one that has low temperature charge protection and you probably want to put them in a place you can keep from freezing.
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True. They can be discharged safely when it's cold, but not charged.
A lot of people install them in the (warm) living area for this reason.
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02-05-2022, 02:50 PM
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#6
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Senior Member
Join Date: Jun 2016
Location: SW Louisiana
Posts: 8,939
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Also more and more of them are coming equipped with low temperature disconnect sensors on the BMS, some even with internal heating elements that will use the available charging current warm them before reconnecting the battery to allow charging.
__________________
2002 Safari Trek 2830 on P32 Chassis with 8.1L w/ 400 watts solar 420Ah LiFePo4
2017 Jeep Cherokee Overland & 2007 Toyota Yaris TOADs with Even Brake,
Demco Commander tow bar and Blue Ox / Roadmaster base plates
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02-05-2022, 05:48 PM
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#7
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Senior Member
Damon Owners Club
Join Date: Apr 2020
Location: Clovis NM
Posts: 4,389
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Quote:
Originally Posted by dssl
Lifepo4 batteries will be destroyed if you charge them bellow 32°f, so you want one that has low temperature charge protection and you probably want to put them in a place you can keep from freezing.
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32 is misleading. The maker of my batteries said they are ok down to 15.
__________________
2006 Damon Daybreak 3276 35'with 5 Star Tuner. 3 200 Amp Lithium batteries and 2000 watt PSW inverter/charger. 2013 Elantra on a Master Tow dolly.
Retired USAF
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02-05-2022, 06:29 PM
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#8
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Senior Member
Join Date: Jun 2016
Location: SW Louisiana
Posts: 8,939
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It depends on the specific lithium battery, most are 29-32F for lowest allowed charging voltage
__________________
2002 Safari Trek 2830 on P32 Chassis with 8.1L w/ 400 watts solar 420Ah LiFePo4
2017 Jeep Cherokee Overland & 2007 Toyota Yaris TOADs with Even Brake,
Demco Commander tow bar and Blue Ox / Roadmaster base plates
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02-05-2022, 06:49 PM
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#9
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Senior Member
Join Date: May 2019
Posts: 172
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So, back to the issue of charging voltage and current from the tow vehicle. I note on almost every hookup that my 2017 F350 Ford is charging the 2 deep cell batteries at 14.4 VDC and up to 10 amps - I have a shunt battery monitor. So, on a cold day I won't be able to do that until the batteries get above 32 degF? And I literally need to disconnect them? At a time when I really need that high voltage and amps for the hookup process?
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02-05-2022, 07:51 PM
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#10
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Senior Member
Join Date: Jan 2017
Location: "Murvul", TN
Posts: 1,665
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Quote:
Originally Posted by cletesingler
So, back to the issue of charging voltage and current from the tow vehicle. I note on almost every hookup that my 2017 F350 Ford is charging the 2 deep cell batteries at 14.4 VDC and up to 10 amps - I have a shunt battery monitor. So, on a cold day I won't be able to do that until the batteries get above 32 degF? And I literally need to disconnect them? At a time when I really need that high voltage and amps for the hookup process?
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As a general statement LFP batteries should not be charged when the temperature is 32 degrees or below......check with the battery manufacturer to see what their rated temperature is. 14.4 volts will fully charge a LFP battery to 100% SOC. In fact, 13.8 to 13.9 volts (approx. 3.45 volts per cell) will fully charge a LFP battery. The difference between the 13.8 or 13.9 and the 14.4 is that the 14.4v will charge it more quickly. Having said that, just make sure that you don't try to charge at 32 degrees or lower.....or whatever the battery manufacturer recommends as the cutoff voltage for charging.
The problem with a "traditional" charger that is made for FLA batteries is that it will likely product a Bulk charge voltage of around 14.4 volts (which is just fine), for a certain amount of time, depending on how low the battery's state of charge is. After that, it will switch to absorption mode and that is usually around 13.6 volts. That voltage works out to 3.4 volts per cell which will not get a LFP battery to 100% state of charge. After some further time, it will drop to float voltage, usually around 13.2 volts and that is why most FLA chargers will work, but they just don't fully charge a LFP battery.
__________________
2016 F350 Crew Cab Dually Diesel King Ranch 4x4
2018 Grand Design Momentum 394M Toy Hauler
Excessive Payload Capacity is a Wonderful Thing!
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02-05-2022, 08:16 PM
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#11
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Senior Member
Join Date: Jun 2016
Location: SW Louisiana
Posts: 8,939
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One thing to be aware of here, is that it is true that 13.9 - 14.1VDC is 100% charge on a LiFePo4 battery, but what many fail to realize or appreciate is that the charge curve for LiFePo4 is not linear, and spikes up between 99-100% state of charge, so that 13.6VDC is close to 99% state of charge, and that due to their low internal resistance LiFePo4 batteries don't need that circa 1 VDC voltage difference to push charge into a battery, and will happily get to near equal charge voltage with the charging source fairly rapidly, so a charger that absorbs at 13.6VDC will let a LiFePo4 battery reach 98-99% SOC in fairly short order (typically hours, not days with a reasonably appropriate size charger), and those that do float at 13.2 -13.4 will typically stay in absorption for at least 8 hours before switching to float. This means a 50 amp converter charger with a charge profile of up to 4 hours of bulk charging, followed by up to 8 hours of absorption charging (typically cut off of each stage is based on charge acceptance (resistance, which LiFePo4 will not trip), or timer can pump nearly 50 amps per hour into a LiFePo4 battery bank for 12 hours straight, or in other words nearly 600 Amp hours of power, before switching into float mode. Yes I know that it will tend to be less than 50 amps in the real world, probably closer to 45, but even at 40 amps you are talking about nearly 500 amp hours of power over the 12 hour period before the charger drops into float mode.
__________________
2002 Safari Trek 2830 on P32 Chassis with 8.1L w/ 400 watts solar 420Ah LiFePo4
2017 Jeep Cherokee Overland & 2007 Toyota Yaris TOADs with Even Brake,
Demco Commander tow bar and Blue Ox / Roadmaster base plates
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02-06-2022, 03:41 AM
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#12
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Senior Member
Join Date: Jan 2017
Location: "Murvul", TN
Posts: 1,665
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Quote:
Originally Posted by Isaac-1
One thing to be aware of here, is that it is true that 13.9 - 14.1VDC is 100% charge on a LiFePo4 battery, but what many fail to realize or appreciate is that the charge curve for LiFePo4 is not linear, and spikes up between 99-100% state of charge, so that 13.6VDC is close to 99% state of charge, and that due to their low internal resistance LiFePo4 batteries don't need that circa 1 VDC voltage difference to push charge into a battery, and will happily get to near equal charge voltage with the charging source fairly rapidly, so a charger that absorbs at 13.6VDC will let a LiFePo4 battery reach 98-99% SOC in fairly short order (typically hours, not days with a reasonably appropriate size charger), and those that do float at 13.2 -13.4 will typically stay in absorption for at least 8 hours before switching to float. This means a 50 amp converter charger with a charge profile of up to 4 hours of bulk charging, followed by up to 8 hours of absorption charging (typically cut off of each stage is based on charge acceptance (resistance, which LiFePo4 will not trip), or timer can pump nearly 50 amps per hour into a LiFePo4 battery bank for 12 hours straight, or in other words nearly 600 Amp hours of power, before switching into float mode. Yes I know that it will tend to be less than 50 amps in the real world, probably closer to 45, but even at 40 amps you are talking about nearly 500 amp hours of power over the 12 hour period before the charger drops into float mode.
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I agree that time based charging is not a good thing for LFP batteries, but fortunately, most modern converter/chargers are not time based. Changing states from bulk/boost down to absorption mode is normally based on the charging profile that is programmed into the charger and utilizes tail current to make the determination of when to switch. Current can only flow if there is a voltage differential between what is doing the charging (the charger) and what is getting charged (the battery). So a charger that has dropped down to absorption mode and is at 13.6 will not be sending current to the battery if the battery voltage is also at 13.6 Obviously, 13.4-13.5 would be a better/less stressful voltage to float at for the LFP battery, but most of the LFP battery chargers will float at 13.6, so in my opinion, switching to a LFP charger vs. a charger for FLA doesn't really get you a lot, other than faster charging of the LFP battery. The end result of a battery being floated at 13.6 is the same....not ideal, but workable.
__________________
2016 F350 Crew Cab Dually Diesel King Ranch 4x4
2018 Grand Design Momentum 394M Toy Hauler
Excessive Payload Capacity is a Wonderful Thing!
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02-06-2022, 08:09 AM
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#13
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Junior Member
Join Date: Jul 2020
Location: Reading, PA
Posts: 23
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Old M/H Disable Emergency Start Function
Hi All!
I so appreciate all the input in this forum, both questions and answers! I have made the redo/upgrade project a major hobby on my '97 H/R Vacationer 32cg.
Just finished installing lithium batteries (2ea SOK 206 A/H, mounted under the bed) and a DC to DC 20 amp charger with a dash mounted on/off switch.
I disabled the Emergency Start relay under the hood which is supposed to connect the house and chassis battery systems while driving. (This is in addition to the dash switch and described in the H/R manual.) I added an under-hood toggle switch into the relay wire that closes it with a tag attached so that in an emergency I can use the dash switch if needed. I made this move in order to protect my alternator which is the original (1997) rated for 150 amps and still works well.
I found the idea from this forum and again find so much that to enjoy from you all!
__________________
Dirtman64
1997 Holiday Rambler 32cg Vacationer F53
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