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Old 01-16-2019, 02:40 PM   #1
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Looking for experience with Lithium Conversion

Hey everybody,

I'm looking for somebody that has done a lead-acid battery to lithium battery conversion, as I've got a few questions. Here are the facts thus far.

-I'm looking to replace my two marine deep cycle batteries
-I've already got a Victron solar smart controller (Works great, has lithium function)
-We do a lot of dry camping, I love my solar, never needed a genny
-We camp in the winter up at the ski hill. Colder temps.
-We use power conservatively, our 200W solar setup has lasted us 5+ days


Here are my questions
-I'm looking at either a 150ah battery, or a 200ah battery, is this good?
-When replacing the built-in converter, what charger/converter did you go with?
-How do you get around the cold-weather charging limitation?
-What do you use to measure SOC?
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Old 01-17-2019, 01:23 AM   #2
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I have 2 100AH Battleborns.


700W of solar with a Victron Solr controller and a Victron 712 battery monitor.


I put my batteries under my bed so they are not outside.


I bought a Progressive Dynamics Lithium charger although I rarely even use it with 700W of solar unless I am plugged in at an RV park. I probably could have gotten by with the original converter but it was a WFCO and I wanted the converter as close to the battery as possible.
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Old 01-17-2019, 12:07 PM   #3
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Quote:
Originally Posted by kfergiez View Post
Hey everybody,

I'm looking for somebody that has done a lead-acid battery to lithium battery conversion, as I've got a few questions. Here are the facts thus far.

-I'm looking to replace my two marine deep cycle batteries
-I've already got a Victron solar smart controller (Works great, has lithium function)
-We do a lot of dry camping, I love my solar, never needed a genny
-We camp in the winter up at the ski hill. Colder temps.
-We use power conservatively, our 200W solar setup has lasted us 5+ days


Here are my questions
-I'm looking at either a 150ah battery, or a 200ah battery, is this good?
-When replacing the built-in converter, what charger/converter did you go with?
-How do you get around the cold-weather charging limitation?
-What do you use to measure SOC?
-I'm looking at either a 150ah battery, or a 200ah battery, is this good?
I went with four 100ah Battle Born LiFePO4 batteries. I had originally planned on four 6v GC lead acid batteries. (My CPAP is why I installed four batteries.)
-When replacing the built-in converter, what charger/converter did you go with?
I installed a Samlex EVO-2212 Inverter/Charger. I customized the settings for my Battle Born LiFePO4 lithium batteries.
-How do you get around the cold-weather charging limitation?
If I was planning on winter camping, I would install the LiFePO4 batteries inside the the RV where it was warm.

My FR3 is at a custom RV shop where they are sealing up the battery compartment. It was open air for lead acid batteries. I will be installing battery warmers and/or blankets. But I don't do any winter camping.

Also make sure to install a power disconnect switch on the positive side of your batteries to remove any load when in storage.

-What do you use to measure SOC?
I have a Victron BMV-712. I works great.
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Old 01-17-2019, 12:24 PM   #4
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Originally Posted by babock View Post
I have 2 100AH Battleborns.


700W of solar with a Victron Solr controller and a Victron 712 battery monitor.


I put my batteries under my bed so they are not outside.


I bought a Progressive Dynamics Lithium charger although I rarely even use it with 700W of solar unless I am plugged in at an RV park. I probably could have gotten by with the original converter but it was a WFCO and I wanted the converter as close to the battery as possible.
Thanks for your insight.

I misspoke in my earlier post, for some reason I thought my Victron controller had a lithium function, but it doesn't. I can customize the output voltage, but it's default mode is for lead-acid.

Should I change it over so all three modes of charging at set at a steady 14.6v? I'm afraid it would not recognize when to cut off.
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Old 01-17-2019, 12:41 PM   #5
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I misspoke in my earlier post, for some reason I thought my Victron controller had a lithium function, but it doesn't.
Which model controller do you have?
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Old 01-17-2019, 01:19 PM   #6
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Originally Posted by kfergiez View Post
Thanks for your insight.

I misspoke in my earlier post, for some reason I thought my Victron controller had a lithium function, but it doesn't. I can customize the output voltage, but it's default mode is for lead-acid.

Should I change it over so all three modes of charging at set at a steady 14.6v? I'm afraid it would not recognize when to cut off.
You may need a firmware update. You can get a bluetooth dongle to be able to upgrade. Then you would also be able to monitor with your smartphone.
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Old 01-17-2019, 02:50 PM   #7
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Which model controller do you have?
SmartSolar MPPT 75/15

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Originally Posted by rk06382 View Post
You may need a firmware update. You can get a bluetooth dongle to be able to upgrade. Then you would also be able to monitor with your smartphone.
This model has built-in bluetooth, and the smartphone app is how I manage it. I've already done the latest update, so it should be current.
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Old 01-17-2019, 03:12 PM   #8
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SmartSolar MPPT 75/15



This model has built-in bluetooth, and the smartphone app is how I manage it. I've already done the latest update, so it should be current.
Your charger does not have a battery select. Only the larger ones do. Fortunately, batteries like BattleBorn have built in BMS so you won't have an overcharge issue. The problem you may have is that the charger won't stay in bulk.


Your controller is on the small side to me. If your plan would be to increase your solar array, buy the Victron controller like I have which is the 100/50.


BTW, make sure you put your panels in series if they have built in bypass diodes. Way better than putting them in parallel for your controller or any MPPT controller for that matter. If you have panels that are 18V peak voltage panels instead of 20V, you definitely want to have them in series to take advantage of MPPT.
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Old 01-17-2019, 03:13 PM   #9
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It's OK to leave them partially charged

The Lithium batteries work better not being continually topped off. Lead acid, nickel cadmium, and nickel metal hydride should be fully charged after every use.


In a RV situation it is hard not to charge all the time, when able. Also be aware that you will not see any voltage drop in Lithium batteries until they are about 90% gone. Lead batteries drop in a linear manner with discharge so volt meters work pretty well giving you a state of charge.


To prove the point in the above paragraph, have you owned and used any Lithium cordless power tools? They run perfect and then just stop working. same with a Lithium RV battery.

I run Lead batteries because they are inexpensive and they do what I need to have done.
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Old 01-17-2019, 03:24 PM   #10
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The Lithium batteries work better not being continually topped off.
While I agree with that statement, you do realize that batteries like BattleBorn leave headroom so that the batteries actually never get 100% charged or 100% depleted right?


I always allow my batteries to get to 100% while camping. When I store my trailer for longer than a few weeks, I allow the batteries to be at around 80%.


Your statement about lithium battery voltage not dropping is also false. Here is a chart from Battleborn. It maches what I see with my SOC measured by my Victron 712 very closely.






You have experience with RV lithium batteries? Doesn't seem like it.
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Old 01-17-2019, 03:30 PM   #11
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In a RV situation it is hard not to charge all the time, when able. Also be aware that you will not see any voltage drop in Lithium batteries until they are about 90% gone. Lead batteries drop in a linear manner with discharge so volt meters work pretty well giving you a state of charge.
You're right about that. Here's a voltage chart from BattleBorn:


For measuring state of charge, I use a Victron BMV-702 + bluetooth dongle. Coupled with the phone, it gives a great display of the current state:


Quote:
Originally Posted by kfergiez View Post
Here are my questions
-I'm looking at either a 150ah battery, or a 200ah battery, is this good?
-When replacing the built-in converter, what charger/converter did you go with?
-How do you get around the cold-weather charging limitation?
-What do you use to measure SOC?
I opted for four (4) BattleBorn 100AH batteries. I wrote up the installation here:
Let’s Boondock! Battery upgrade (to lithium)! | Learn To RV

When replacing the converter, I opted for a Progressive Dynamics PDsomething. It was a direct replacement for what I had before.

For the cold-weather charging limitation, BB has been getting to allow colder weather. I think they also have some battery "blankets" things that are supposed to help. I personally avoid freezing temps intentionally. If I was going to be doing it regularly, I would move the batteries to somewhere that is more temperature friendly that my ducting would heat up. In my fifth wheels, that space is under the steps/landing- it's usually dead space that could be utilized.

As I mentioned above, I measure SOC with the Victron BMV.

If you can program the output of the Victron inverter, you can contact your battery manufacturer (in my case, it was BattleBorn) and they'll tell you or help you figure out what settings to use.
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Old 01-17-2019, 03:44 PM   #12
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Your charger does not have a battery select. Only the larger ones do. Fortunately, batteries like BattleBorn have built in BMS so you won't have an overcharge issue. The problem you may have is that the charger won't stay in bulk.

That's good to know that the battery's BMS will prevent overcharge. That makes things easier.

Your controller is on the small side to me. If your plan would be to increase your solar array, buy the Victron controller like I have which is the 100/50.

200W seems to serve us well, and with our small trailer, we're pretty constrained on panel real estate. Does the 100/50 have battery type select?

BTW, make sure you put your panels in series if they have built in bypass diodes. Way better than putting them in parallel for your controller or any MPPT controller for that matter. If you have panels that are 18V peak voltage panels instead of 20V, you definitely want to have them in series to take advantage of MPPT.

Absolutely! Our panels are in series and they do have a bypass diode built in.
...
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Old 01-17-2019, 03:51 PM   #13
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The 100|50 does have the battery select.


There are a few Facebook pages run by a mobile installer that does it "his way or the highway" that insists that you always run in parallel. Of course he gives no good technical reason to do it that way. I actually have the panels he promotes which allow the panel to operate with half voltage so if one panel in my 2 string get shaded, I still get 75% power. Do that with a parallel panel and that panel delivers 0.



Good that you are running in series. I run 2 strings with 2 panels each so I at least get 72 cells in series which is what Victron reccomends with their controllers.
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Old 01-17-2019, 03:51 PM   #14
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Your statement about lithium battery voltage not dropping is also false. Here is a chart from Battleborn. It maches what I see with my SOC measured by my Victron 712 very closely.

Yes and no. It is well known that lead-acid batteries drop in voltage in a fairly linear way. Lithium on the other hand is pretty flat. Battleborn's batteries actually have more voltage drop than I expected. Other batteries experience maybe a 1% drop in voltage between 90% and 30% SOC. That's why a standard voltage meter is so difficult to use to measure SOC on lithium batteries.

I may be wrong, but I believe the victron BMV acts more like a coulomb meter than a voltage meter.


You have experience with RV lithium batteries? Doesn't seem like it.

No need to be rude.
. . . . .
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Old 01-17-2019, 03:56 PM   #15
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The Victron BMV measures the current in and out of the battery to determine SOC. It's just a shunt and measures current over time.It also uses a Peukert constant setting to correct for discharge losses which mainly applies to lead acid batteries but there is a small constant for Lithium. Lithium has an extremely low internal impedance which is why Lithium batteries are so great.


The voltage drop from full to 50% on a FLA is around 0.7V. For a LiFePO4 is around 0.5V.
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Old 01-17-2019, 04:01 PM   #16
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If you are getting the Victron BMV, definitley go with the 712 which is the latest model. It has builtin Bluetooth and has a fraction of the operating current draw of the older 700 models.
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Old 01-17-2019, 04:07 PM   #17
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If I were to install 2-4 lithium batteries, do I need to take special precautions regarding balancing them? Or is it as simple as hooking them up in parallel and letting their respective BMS's take care of things?
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Old 01-17-2019, 04:09 PM   #18
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If I were to install 2-4 lithium batteries, do I need to take special precautions regarding balancing them? Or is it as simple as hooking them up in parallel and letting their respective BMS's take care of things?
BattleBorn instructions said to separately charge them initially and then yearly but otherwise, plug and go.
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Old 01-17-2019, 04:14 PM   #19
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If I were to install 2-4 lithium batteries, do I need to take special precautions regarding balancing them? Or is it as simple as hooking them up in parallel and letting their respective BMS's take care of things?
Don't have to do anything over time. They are in parallel already. The only time you would need to do any balancing is if you put 2 in series for a 24V system which is the max number in series BattleBorn allows at present.


Before I put my 2 batteries in parallel, I made sure they were at the exact same voltage. If one happened to be discharged more, you could get a massive current from one to the other which would likely burn you as you hooked them up. You can also connect some light weight wires between them. The voltage drop across the wire would limit the current until they were balanced with each other.


Mine were completely charged to 13.6V when I received mine. You definitely want to check though.
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Old 01-17-2019, 04:18 PM   #20
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I'm still working out the issue with charging with my current solar controller. I'd rather not replace it if I can help it.

I'm thinking of just setting my Bulk, Absorption, and Float charge numbers to 14.6v and let the BMS handle the rest. Is their any harm in doing that?
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