New questions about lithium batteries

[saflyer]

I’m getting closer to installing my LiFePO batteries. I just read something I hadn’t thought of before. Actually, in a way the subject did come up. Previously, the issue arose that lithium house batteries may not be very useful to help the chassis batteries if they are too low to start the engine.

Now an added issue. I only recently found out my generator uses the house batteries to start. It was pointed out in an article I read that lithium batteries don’t have the current capacity needed to start a diesel generator. I do know that I usually have to crank the generator starter for some time when it is cold. Is this going to be a problem?

Question two. I was planning to add a DCDC charger to effectively use the engine alternator to charge the lithium house batteries. Now I learn about a product called a battery combiner that will need to be upgraded. I have no idea what one of those is. I read the description but remain confused. Is it the same as my Trombetta relay? Does it replace it? I know the two voltages of the different battery banks are compared to tell the system when to charge the house batteries when the alternator is charging? Can someone educate me on this?

Ed         
’05 HR Ambassador 

From amsolar.com:

2.  Alternator Charging:  When upgrading to lithium batteries you will need to upgrade your battery combiner for alternator charging. Without this modification, the higher resting voltage of a lithium battery will trick the existing battery combiner relay into thinking the alternator is running and the lithium battery bank will be paralleled to the starter battery, even when the ignition is turned off. The result is lithium batteries draining into the starter battery until they crash to a dangerously low voltage or the lithium batteries’ internal BMS engages, preventing further discharge.

If you have a lithium battery system that can handle a charging current of 150A or more (three or more Battle Born lithium batteries), and you do not have a smart alternator (here’s the Smart Alternator Test) you use the Victron Cyrix-Li-Ct battery combiner, variant “Lithium / 230A”.

The Victron Cyrix-Li-Ct can quickly charge a lithium battery up to about 80% state of charge.

If you have a smaller battery bank (one or two Battle Born batteries) and/or a smart alternator, you will need to use the Sterling Battery to Battery Charger. The Sterling is programmable for any battery chemistry and can bring a battery up to 100% state of charge.

Neither device is needed if you plan on using AGM batteries.

Estimated Installation Labor
High Current Alternator Charging
3 hours / $435

 

Victron Cyrix Battery Combiner

from 40.00

Victron Cyrix battery combiners connect your house battery bank to your starter battery and alternator to allow alternator charging. Additionally, when a charge is applied to a house battery bank the Cyrix will close and allow current to flow to the starter battery. Select an appropriate Cyrix based on your house battery type and alternator current rating.

Alternator 160A or less - 120A Cyrix
Alternator more than 160A - 230A Cyrix

Battery Type / Rating: 

         Select Battery Type / Rating         AGM / 120AAGM / 230ALithium / 120ALithium / 230A       

Quantity:

ADD TO CART

 

Sterling Battery to Battery Charger 12V/60A

425.00

This device is ideal for lithium alternator charger system upgrades in motorhomes where a smart alternator is used, or when the lithium battery bank cannot handle high current.

 

 

 

Edited January 19, 2021 by saflyer

[Pepperell]

You probably won’t need to charge the LiFePO4 batteries with the alternator anyway.  Your inverter/charger will charge them in about an hour or so when you plug in the shore power.  And hopefully you’ve sized your battery bank to keep the fridge and furnace running for 24 hour or so.  
Starting the genset shouldn’t be a problem if the LiFePO4’s are above 40f.
2 & 3 cylinder diesel’s aren’t all that tough to start.  Plus the lithium’s have a slightly higher nominal voltage.  
If you have solar, that will also help to keep the bank charged up.  
 

Background info:  I added 4 75ah Relion LiFePO4’s to my 2003 Dynasty in 2016, set the modified square wave inverter to  AGM, no equalize; let the alternator charge engine plus house, and went on my merry way.  It didn’t seem to have any bad effect on engine or house bats.
I replaced the crappy old inverter to a full sine wave type which let me customize the charge profile to float at 13.8v that the Relion’s will accept.  
Fast forward 3 years, the 2003 Dynasty was totaled in an accident from which I was able to salvage the batteries.   Replaced it with a 2006 Dynasty.  It came with 8 AGM’s which I’ll replace with the Relion’s. I have a Magnum inverter in this coach, but it has the old controller that I’ll need to replace with newer type.  Also, this coach came with 4 100w solar panels, but the mppt is an obsolete Heliotrope that I have no documentation for.  I don’t think I can adjust/update the charging profile for the lithium’s.  I’ll likely have to replace it.  
 

Carl

edit:  you might try priming the genset by pressing the switch in the  “stop” (prime) position for a minute or so if its cold out or been sitting for a while.  

Edited January 21, 2021 by Pepperell
Forget to say...

[Ivylog]

Got a good deal on 26 100AH Lithium cells for $900. Built two 300AH batteries with 6 BMS... $1200 total and probably 8 hours.
We do some dry camping in cold weather and putting them outside in the battery compartment would require insulation and a heater plus the house AGMs still have more years in them...haven’t removed yet.

Found a compartment with a AquaHot radiator/fan under the washer dryer in the BR  with room for the 2 Lithium batteries. Built 2 wooden platforms to level the area and cut a rectangular hole in the floor for the wiring to the rear run box which is right behind.... short wire run to the battery banks.

Added a 500A fuse and a battery switch ... off, 1, 2, 1&2. Already had a 100A charger that I’d  previously mounted above the RRBox...will use it to finish charging the Lithium’s higher voltage.

Instead of a dc-dc alternator limiter I’m mounting on the alternator, a switch that opens at 200 degree turning the alternator off. I already run the generator after dry camping before getting on the road.

1st picture is the batteries partially completed.

2nd picture is the 2 platforms the batteries rest on.

3 picture is batteries shoehorned into place.

 

[96 EVO]

Don't know if your 05' will be the same, but I switched mine from house bank to chassis bank feeding the gen starter, easily with a short battery cable and a ANL fuse holder. All done in the rear run box. Took about 15min.

[waterskier_1]

I'm not sure about the Ambassador, but Dynasty & Exec that year have two buss bars in the Front Run Bay; one connected to the chassis battery & one connected to the house batteries.  That is where the generator feed connects.  It is a fairly simple matter of moving that generator feed from the house battery buss to the chassis battery buss. 

Regarding the alternator charging units, I did some research and most are designed to proofread the alternator from overheating by the batteries trying to draw too much current.  One solution was to simply turn oh the charge for a short time, then disconnect the lithium batteries for a while & then repeat.  There was no feedback as to the charge status of the lithium batteries.  I consider, from an engineering reference, they are "feel good" red-neck patched.  

You don't say what you have for solar, but my recommendation is to completely isolate (except for emergency "boost") the two systems.  That is what I have done, even with just Lifeline AGM batteries.  I generally begin a drive with mostly charged house batteries (>80% SOC) so I don't need my house batteries sitting under a 14.4 volt charge for 6 to 10 hours.  Plus I have 1400 Watts of solar on the roof which will keep them topped off & power anything on the house side when traveling. I have dedicated the original 100 Watt solar panel solely to the chassis battery which will maintain the fully charged chassis battery while parked w/o shore power.  This works for me.   If/ when I move to Lithium Batteries, I'll keep the same configuration. 

 

Edited May 31, 2021 by waterskier_1

[Ivylog]

I called Magnum (Sensata) about upgrading my ME-RC50 remote revision 1.6 to a version (2.9+ with custom settings) for Lithium... one that old cannot as supposedly it needs hardware changes. Not sure it’s worth $175 to buy a newer version as I’m topping the Lithium off with a separate PowMax charger plus the BMS stops the charging when the voltage gets to 14.6. 

[waterskier_1]

21 minutes ago, Ivylog said:

I called Magnum (Sensata) about upgrading my ME-RC50 remote revision 1.6 to a version (2.9+ with custom settings) for Lithium... one that old cannot as supposedly it needs hardware changes. Not sure it’s worth $175 to buy a newer version as I’m topping the Lithium off with a separate PowMax charger plus the BMS stops the charging when the voltage gets to 14.6. 

You do not want to leave the lithium batteries connected to 14.4 for more than the time it takes to replenish the charge (usually around 30 minutes for 100 A-Hr battery).  After that you want to decrease to below 13.5 Volts.  You do not want or need to float lithium batteries.  You don't want to keep lithium batteries stored with Moyer than 80% SOC for extended time.  Itmight be good to research all these parameters before you being designing your own charging system.  I've found that battery manufactures (versus the individual cell manufacturers) will tell you pretty much what you want to hear to make a sale.  Most battery sales people don't understand the engineering design that takes place.  I'm not aware of any battery manufacturers that actually manufacturer the cells they incorporate into their batteries, nor the BMS, but not 100%sure on the BMS, since I haven found one suitable for my needs and will likely design my own. 

[Ivylog]

I have studied what’s best for Lithiums. I’m currently discharging the Lithiums down to 60% SOC as it will be a month before getting on the road. Also didn’t charge the cells up since buying them several months ago until this past week to check the operation of the 6 BMS that have led indicator lights for their status... indicates when it’s reached 14.6V and stopped the charging. I’m using the second charger strictly for topping the Lithium’s up and I can turn it off using the block heater switch... no float charging.

During the winter while on FHU (or in long term storage) I’ll keep them at 50% SOC.

[wamcneil]

On 1/19/2021 at 9:23 AM, saflyer said:

.... I was planning to add a DCDC charger to effectively use the engine alternator to charge the lithium house batteries. 

 

Sterling Battery to Battery Charger 12V/60A

425.00

This device is ideal for lithium alternator charger system upgrades in motorhomes where a smart alternator is used, or when the lithium battery bank cannot handle high current.

 

 

 

So... I've got a related philosophical question...

What's the difference between a $425 60a DCDC charger, and a $100 60a PWM solar charge controller???

Why not just put a pwm solar controller between the alternator and the house batts? I'm not sure the solar controller cares what kind of technology is pushing the electrons.

Cheers,

Walter 

[Ivylog]

You size the solar controller for how many amps the panels can supply, not the other way around.  More than likely you would burn the 60A solar controller up with a 160+ amp alternator feeding it.

[wamcneil]

Nah. Solar controllers are routinely undersized with respect to the rated amperage of the panels. The controller will modulate itself down to its rated capacity. 

Cheers,

Walter

[waterskier_1]

2 hours ago, wamcneil said:

So... I've got a related philosophical question...

What's the difference between a $425 60a DCDC charger, and a $100 60a PWM solar charge controller???

Why not just put a pwm solar controller between the alternator and the house batts? I'm not sure the solar controller cares what kind of technology is pushing the electrons.

Cheers,

Walter 

The difference between a PWM or even a better MPPT controller is that they require a higher voltage (usually 18-24 volts) input to regulate down to 14.4 or lower output.  They can no increase the voltage.  A DC-DC charger/converter/controller, it goes by many names, but the main factor is it converts DC to AC, which then can go through a transformer and be increased or decreased, before rectifying and filtering it to yield DC out.  This means that a 14.2 Volt Alternator voltage can be "transformed" to over 16-18 Volts and then made back to DC at a voltage higher than 14.2 volts (typically a lithium battery likes 14.4 - 14.6 volts).  

[wamcneil]

Yeah, that's why I specified PWM. MPPT would serve no purpose in this application.

As long as the alternator voltage is sufficient to charge the battery (which it is...), that's all that's needed, right? The charge controller will run wide open till it hits rated amperage, or the voltage reaches absorption voltage. Then it'll throttle back.

The alternator provides enough volts to charge the lithium battery, so it doesn't need to be upconverted, just throttled back to the lithium battery's preferred voltages for absorption and then float or terminate. This might not be the fastest charge profile possible, but I'm not that interested in the shortest possible charge cycle. 

Why would the solar controller care if its current is coming from an alternator or a solar panel????

Cheers,

Walter

[waterskier_1]

5 hours ago, wamcneil said:

Yeah, that's why I specified PWM. MPPT would serve no purpose in this application.

As long as the alternator voltage is sufficient to charge the battery (which it is...), that's all that's needed, right? The charge controller will run wide open till it hits rated amperage, or the voltage reaches absorption voltage. Then it'll throttle back.

The alternator provides enough volts to charge the lithium battery, so it doesn't need to be upconverted, just throttled back to the lithium battery's preferred voltages for absorption and then float or terminate. This might not be the fastest charge profile possible, but I'm not that interested in the shortest possible charge cycle. 

Why would the solar controller care if its current is coming from an alternator or a solar panel????

Cheers,

Walter

There are two things you are not considering.  The first is that some (most?) lithium batteries require a higher voltage than the alternator (without modification to it's Voltage Regulator, which is often built-in) than the alternator produces.  As I mentioned above, most alternators put out 14.2 volts.  Lithium batteries require 14.4 - 14.6 Volts.  So, assuming there are not electronics involved, only a straight wire, your alternator will not charge the lithium batteries to 100%.  

But the other aspect which may not be as obvious, is that there is - there has to be - a voltage loss or drop across most devices, including all Solar Controllers.  It takes a higher voltage input to the device than what the device can regulate output.  Consider the simple Solid State (Diode) Isolator.  Each diode junction has a fixed voltage drop of 0.3 to 0.7 volts (depending on the chemistry of the diode and the current flowing through it).  That is why, decades ago, the remote sensing (Monacoers know it as DUVAC) voltage regulators were developed.  No, I'm not saying that the internal voltage regulator in our alternators (or an external regulator on a new replacement alternator) could not be developed, that would regulator the alternator output correctly for lithium batteries.  I'd be quite surprised if that doesn't already exist.  The problem is that would make the new alternator charging system incompatible with lead acid, AGM, gel cell battery technology.  So, the problem isn't that the alternator can't do the job, it is that it's more difficult to find a solution is we decide to use the same source for charging two different battery technologies.  The same holds true for the inverter/charger running off shore power (or generator) and attempting to charge the chassis battery with the lithium battery profile.  It's just a bit easier to decrease the voltage from what is supplied than to increase it (when it's direct current).  That's the main reason that alternating current still exists.  

The solution for me (as I mentioned before, I still only have AGMs because of the cold climate I store my coach) I don't let my alternator charge my AGM batteries.  I don't like the idea of having 14.2 volts for 8 hours or more applied to my house batteries.  I did the same thing with my old Dynasty even after I replaced the AGMs with conventional Trojan Lead Acid batteries.  I seldom need the alternator to charge my house batteries since they are already charged when I disconnect from shore power, and I have plenty of solar power to maintain them while I drive.  I typically don't drive at night for hours. 

 

[fredelkamp]

On 5/31/2021 at 11:24 AM, waterskier_1 said:

... my recommendation is to completely isolate (except for emergency "boost") the two systems... 

 

My solar installer completely disconnected the the Trombetta to isolate the LiFePO4 Batteries from the chassis AGM batteries. The 1440 watts on the roof keeps the house batteries nicely  charged, but parasitic draw on the chassis batteries when we are parked will kill them in about two weeks so I put in an AC trickle charger to maintain them. How can restore the emergency "boost" system?

[saflyer]

An RV tech showed me an item in the front run bay that is connected to the Trombetta. Said if I pull one item out it keeps the alternator from charging the house batteries but the emergency boost function is still available. Unfortunately I don’t remember what is to be pulled and that tech is no longer around.

Another thing to consider. I installed a Trik-L-Start to keep my chassis batteries charged while on shore power. That company says it won’t work with lithium batteries but their latest models of Amp-L-Start will.             

Ultimately I tend to agree with not charging the house batteries from the alternator and just figure there will always be enough solar while I drive to run the few things operating, mainly the refrigerator.

Edited June 8, 2021 by saflyer

[Ivylog]

Several years ago I added a manual disconnect switch to the wire that energizes my BigBoy relay to decrease its amp draw when dry camping…switch extends out the bottom of the rear run box. 
Just ordered a $12 WiFi relay to go in parallel with this switch so I do not have to go outside to put the BigBoy back in the system. Decided on the one below as it appears to have an antenna wire that I can run outside of the metal rear run box for better reception.

[saflyer]

On 6/1/2021 at 11:35 AM, waterskier_1 said:

You do not want to leave the lithium batteries connected to 14.4 for more than the time it takes to replenish the charge (usually around 30 minutes for 100 A-Hr battery).  After that you want to decrease to below 13.5 Volts.  You do not want or need to float lithium batteries.  You don't want to keep lithium batteries stored with Moyer than 80% SOC for extended time.  

I’ve never read this before. Where is this information from? Not that I don’t think you have it right but I’d like to learn more.

[Ivylog]

I’ve read much the same  for voltages plus for extended storage, 6 months, you want them at 60% or even 50% SOC to keep the positive post from being damaged.

[waterskier_1]

2 hours ago, saflyer said:

I’ve never read this before. Where is this information from? Not that I don’t think you have it right but I’d like to learn more.

Check out any of the DIY lithium battery design sites.  I think BattleBorn batteries states it under charging specs. 

[waterskier_1]

3 hours ago, fredelkamp said:

My solar installer completely disconnected the the Trombetta to isolate the LiFePO4 Batteries from the chassis AGM batteries. The 1440 watts on the roof keeps the house batteries nicely  charged, but parasitic draw on the chassis batteries when we are parked will kill them in about two weeks so I put in an AC trickle charger to maintain them. How can restore the emergency "boost" system?

It depends on what he did to disconnect it.  Does your alternator still charge your house batteries?  That is typically accomplished through the same relay. 

[fredelkamp]

1 hour ago, waterskier_1 said:

It depends on what he did to disconnect it.  Does your alternator still charge your house batteries?  That is typically accomplished through the same relay. 

Nope, the house batteries are quickly charged by the 1440 watts of solar panels on the roof, I even have turned off the Magnum charger and the Victron Orion DC-DC Charger connected to the alternator.

He removed the two battery bank jumper cables going to the Trombetta. You can see the jumper cables in the bottom of the first picture I posted. I assume I'll need to reinstall the jumpers and remove the purple "relay" wire from the Bird in the front run distribution box below the driver seat in the outside compartment.

 

Edited June 9, 2021 by fredelkamp

[waterskier_1]

I don't know your physical layout, but toss wires don't look long enough to reach the chassis batteries, so I'm assuming that there is an intermediary connection point.  Generally, the purple wire come from the BOOST switch or the Isolator Relay Delay (IRD) - the other was usually a red wire - both went to the same terminal on the relay coil.   The other terminal (no wire attached seen in the pictures) went to ground.  Removing the wire from the front run bay would not allow the BOOST switch to operate.  I believe you would need to leave the wire to the boost switch, remove the white from the IRD and connect ground to the other coil terminal.   And the positive terminals need to be reconnected to the relay large terminals.  It might be easier (assuming you'd use this function rarely) to just jumper the two positive batteries together. 

[saflyer]

12 hours ago, waterskier_1 said:

 It might be easier (assuming you'd use this function rarely) to just jumper the two positive batteries together. 

That seems to be the simplest thing to do.