LiFeP04 Lithium batteries - Must read!!!

[gpounder]

Hidden in a drop-in battery is construction differences. Will Prose does a great job of showing what quality looks like.

One area of concern for the batteries that are made of small cells (the size between a AA and C cell) is the ability for them to withstand vibration. Every one of these small batteries and there may be several hundred of them is the fact they are all soldered together. Vibration is not a friend to this type of construction. They may be great for a home solar system but not so great for a RV. The better option is a prismatic cell.

[jcussen]

Originally Posted by gpounder

The BMSs I have seen all have little non load bearing wires just for sensing voltage. The purpose is to monitor cells internally so that the first cell the reaches high or low value turns off the entire unit. it is not a bypass. That is the point of balancing the cells so they all respond as a unit.

They do the same for all types of cells.

Imagine just for e moment you bypass a 3.6 volt cell, that would make your 14.4 volt battery a 10.8 v, worthless.

I can watch my leaf battery through a bluetooth app. When a cell reaches, say its high limit voltage, it connects it to a cell with lower voltage and balances the cells, have never seen it disconnect a cell completely. They start to balance at 3.9 volts and stop charging to that cell at 4.1 volts, still in the circuit but not receiving a charge, if charging, that cell will connect to a lower voltage cell to balance. This is on a top balance BMS, not sure how it works on other BMS's

[757driver]

Originally Posted by jcussen

One reason I went with Battle Born for the coach. Have never seen or heard of a catastrophic Battle Born failure. Will Prowse, who has tested more lithium batteries than I knew existed, thinks pretty highly of them.

Totally agree, Battleborn makes a great battery. Will has put out some good articles and videos on lithium batteries. There are pros and cons to each type of lithium battery (prismatic and cylindrical), just pointing out one difference.

[jcussen]

My Tesla has over 6000 individual cells. More vibration in my car than in my coach.

https://www.youtube.com/watch?v=c0IHNrW0QOA

[Teamfoxy]

Most people only have issues with lead acid batteries because they don't keep them watered properly. Installing a single point watering system makes that easy no matter how buried the batteries are. Just hook up the pump once a month, done! 6V golf cart batteries are cheap and we get 5 years from them.

[Persistent]

Originally Posted by gpounder

The BMSs I have seen all have little non load bearing wires just for sensing voltage. The purpose is to monitor cells internally so that the first cell the reaches high or low value turns off the entire unit. it is not a bypass. That is the point of balancing the cells so they all respond as a unit.

They do the same for all types of cells.

Imagine just for e moment you bypass a 3.6 volt cell, that would make your 14.4 volt battery a 10.8 v, worthless.

Check out the utube vid above. They have multiple banks of cell. Cells in each bank are in parallel. You can take one cell out of a bank and it will still be the same voltage out, but lower capacity. In Battle Born, each cell has built in safety devices that can disconnect individual cells.

In the Battle Born, each bank is charged separately. Each bank will stop charging when it is full. Each bank is individually managed. On output, the four banks are in series. Disconnecting one bank disconnects the whole battery.

There is probably more, but I could not easily replay it so you are on your own.

[Rockets160]

Long story short- New RVers and we purchased the coach a few months back and been on a few short trips where we had full hookups. Never a need to use the house batteries. We're planning to do a longer trip around Thanksgiving and checked how much time we would have available on batteries. Turns out, the manufacture date of the battery was Nov 2005- somehow, we managed about 10 minutes (LOL) with just lights and the tv on. It was deader than dead...

So, we have decided to switch from flooded lead acid to Lithium phosphate. I spoke with Magnum energy and have the updated firmware card for my inverter converter, and an updated remote inbound- these will allow custom/ lithium charging profiles to be input so the lithiums charge correctly.

The question I have is: will the flooded lead acids I have as chassis starting batteries interfere with charging or discharging? I've read arguments on both sides that say I'll need an isolator- but isn't that what the "big boy" relay is? Doesn't the Battery Control Center manage the charging levels? These arguments typically ignore the fact that I haven't heard of anyone using lithium as starting batteries- most use AGM, so how is that managed unless by the BCC?

I've also heard arguments that the lead acids may lose some life- I'm not too concerned about replacing them unless they pose a safety hazard.
Any help is appreciated.

Jeff
2005 American Eagle 40L
400 Cummins

[gpounder]

Originally Posted by Rockets160

Long story short- New RVers and we purchased the coach a few months back and been on a few short trips where we had full hookups. Never a need to use the house batteries. We're planning to do a longer trip around Thanksgiving and checked how much time we would have available on batteries. Turns out, the manufacture date of the battery was Nov 2005- somehow, we managed about 10 minutes (LOL) with just lights and the tv on. It was deader than dead...

So, we have decided to switch from flooded lead acid to Lithium phosphate. I spoke with Magnum energy and have the updated firmware card for my inverter converter, and an updated remote inbound- these will allow custom/ lithium charging profiles to be input so the lithiums charge correctly.

The question I have is: will the flooded lead acids I have as chassis starting batteries interfere with charging or discharging? I've read arguments on both sides that say I'll need an isolator- but isn't that what the "big boy" relay is? Doesn't the Battery Control Center manage the charging levels? These arguments typically ignore the fact that I haven't heard of anyone using lithium as starting batteries- most use AGM, so how is that managed unless by the BCC?

I've also heard arguments that the lead acids may lose some life- I'm not too concerned about replacing them unless they pose a safety hazard.
Any help is appreciated.

Jeff
2005 American Eagle 40L
400 Cummins

The best battery to start your vehicle is lead acid flooded or sealed. They are best suited for the high current discharge.

I run lithium for the house and lead acid for the chassis and have a cross over charger when plugged in and a relay to connect the two set together when driving. There is no problem doing this even though the charge profiles and operating voltage are different because at 13.8 volts (alternator) the lithium will slow charge and not hurt the alternator. When charging the chassis battery when plugged in the higher lithium voltage is limited by the trickle charger so no harm either. The only warning is if you try to charge the lithium at or below 32deg F you will injure them.

[Rockets160]

Originally Posted by gpounder

The best battery to start your vehicle is lead acid flooded or sealed. They are best suited for the high current discharge.

I run lithium for the house and lead acid for the chassis and have a cross over charger when plugged in and a relay to connect the two set together when driving. There is no problem doing this even though the charge profiles and operating voltage are different because at 13.8 volts (alternator) the lithium will slow charge and not hurt the alternator. When charging the chassis battery when plugged in the higher lithium voltage is limited by the trickle charger so no harm either. The only warning is if you try to charge the lithium at or below 32deg F you will injure them.

Is the crossover charger and relay different from the Battery Control Center installed by the factory? My understanding of the BCC:
it's sole purpose is to monitor and switch charging from house batteries to starting batteries depending upon which needs to be charged. Which sounds exactly like what your crossover and relay do.
Jeff

[CountryFit]

Originally Posted by Rockets160

Long story short- New RVers and we purchased the coach a few months back and been on a few short trips where we had full hookups. Never a need to use the house batteries. We're planning to do a longer trip around Thanksgiving and checked how much time we would have available on batteries. Turns out, the manufacture date of the battery was Nov 2005- somehow, we managed about 10 minutes (LOL) with just lights and the tv on. It was deader than dead...

So, we have decided to switch from flooded lead acid to Lithium phosphate. I spoke with Magnum energy and have the updated firmware card for my inverter converter, and an updated remote inbound- these will allow custom/ lithium charging profiles to be input so the lithiums charge correctly.

The question I have is: will the flooded lead acids I have as chassis starting batteries interfere with charging or discharging? I've read arguments on both sides that say I'll need an isolator- but isn't that what the "big boy" relay is? Doesn't the Battery Control Center manage the charging levels? These arguments typically ignore the fact that I haven't heard of anyone using lithium as starting batteries- most use AGM, so how is that managed unless by the BCC?

I've also heard arguments that the lead acids may lose some life- I'm not too concerned about replacing them unless they pose a safety hazard.
Any help is appreciated.

Jeff
2005 American Eagle 40L
400 Cummins

I didn't read the whole thread, just to throw in some of the info for your reference.

My li battery pack is 1200ah at 12v. Over a period of time, I had both house in li and chassis in lead acid. After realizing that I was mostly only using about 200ah overnight, I decided to delete the chassis battery, and connect the starting cables to the house battery pack directly. It has been running like that for 5 years now, no problems.

My original chassis battery had 1400cca spec. I tested with 100ah li batt, it started engine perfectly.

Steven

[Persistent]

Originally Posted by Rockets160

Is the crossover charger and relay different from the Battery Control Center installed by the factory? My understanding of the BCC:
it's sole purpose is to monitor and switch charging from house batteries to starting batteries depending upon which needs to be charged. Which sounds exactly like what your crossover and relay do.
Jeff

There are lots of different configurations in RV's and I am not experienced with yours. LiPO4 and lead acid have different charging and discharging profiles. Deciding when the house charger should charge chassis batteries and when engine alternator should charge house batteries is all different.

What voltage to regulate at is different for lead and Li and a large Li bank can draw enough current to over heat an alternator. The solution is sometimes to add a battery to battery charger that can control charging differently for the different chemistry.

Battle Born will probably have good advice for how to combine their batteries. They seem to have actually tested various systems. Other Li battery mfg may also give good advice.

I wish you good luck and happy trails ahead!

[SV K]

Installed 1000amps of lifepo4 house battery in 2014. At the time the coach had several year old AGM’s for chassis batteries. Installed a Balmer programmable alternator controller to keep the charging amps down to protect the alternator, not the batteries.

6+ years of full time timing with 6-8months boondocking each year the coach is stlll starting just fine with those chassis batteries.

When putting the Lifepo4’s in we considered the chassis batteries, but figured that under charge the amps would flow toward the path of least resistance, the Lifepo4’s, and therefore not overcharge or harm the AGM’s. So far the concept has obviously worked.

Dis-charging of chassis batteries should not occur unless your chassis and house are tied together when parked.

My new to me coach has lead/acid starts and I see no reason they would be effected using the same design.

I also upgraded my Magnums as you did for that first install. They have worked just fine.