Converting to lithium...keep my converter (for now)?

[xrated]

I have to ask this. With stock converter and the solar panels would the batteries get to 100%? I am a bit confused because if the converter can only charge say to 80%, wouldn't the solar pick up the slack?

3.45V per cell, or 13.8V at the battery is considered by most to be fully charged for a LFP battery. As has been mentioned a lot on this forum during different threads, the problem with getting them fully charged with a non LFP charger setup is whether or not the charger will even put out 13.8 volts or more, and if it does, will it stay at that voltage long enough to fully charge a LFP battery before the float voltage kicks in and isn't enough to finish bringing the battery to full charge. In most cases, the answer is no, they will not fully charge a LFP battery.

[SolarPoweredRV]

I have to ask this. With stock converter and the solar panels would the batteries get to 100%? I am a bit confused because if the converter can only charge say to 80%, wouldn't the solar pick up the slack?

Yes, your Solar Charge Controller will charge to a higher voltage than your Converter, if it has a setting for Lithium batteries.

[SolarPoweredRV]

I do not know. Right now, I do not have solar so I can't say for certain. There are plenty of people here that do and maybe they can share their results.

If the converter is putting out 13.6v and your solar is putting out 14.2v [just throwing out numbers], those numbers would cancel out some how because you are not going to have both voltages at the same time. Would the converter eat up that voltage differential? Would the solar just drop the voltage?

Then you have to ask yourself, why would you have both going at the same time? Because you are too lazy to turn off the solar or unplug from the grid? I am lazy so I can see that is the only reason me doing it.

Let me answer your last question first, yes, you should be too lazy to switch one off. If your system is designed properly, you can set it and forget it. Granted it may take a few trys to get the system set the way you want it, but you should be able to ignore your system (for the most part) once everything has been setup.

For example: my system is intentionally setup very much like having an OEM Converter and Solar system. The two systems work in tandem to charge my battery bank. I consider my Solar as the primary source for charging the batteries. Consequently, my Inverter/Charger is set to charge the batteries to a lower voltage than the Solar Charge controller. My reasoning is this: if I am plugged into Shore Power, my batteries do not need to be fully charged (because Shore Power is available). This also works if I run my Generator to charge the batteries, the generator charges the batteries to ~ 80% and the Solar fills them up during the day.

Having an OEM converter and a Solar system (set for Lithium batteries) would work the same way.

PS: I have never run my Generator just to charge the batteries, I run the Generator to operate my A/C unit for longer periods.

[LanerC]

Let me answer your last question first, yes, you should be too lazy to switch one off. If your system is designed properly, you can set it and forget it. Granted it may take a few trys to get the system set the way you want it, but you should be able to ignore your system (for the most part) once everything has been setup.

For example: my system is intentionally setup very much like having an OEM Converter and Solar system. The two systems work in tandem to charge my battery bank. I consider my Solar as the primary source for charging the batteries. Consequently, my Inverter/Charger is set to charge the batteries to a lower voltage than the Solar Charge controller. My reasoning is this: if I am plugged into Shore Power, my batteries do not need to be fully charged (because Shore Power is available). This also works if I run my Generator to charge the batteries, the generator charges the batteries to ~ 80% and the Solar fills them up during the day.

Having an OEM converter and a Solar system (set for Lithium batteries) would work the same way.

PS: I have never run my Generator just to charge the batteries, I run the Generator to operate my A/C unit for longer periods.

I have add a PD 90 amp lithium converter to my original (replaced with 60 amp PD lithium converter) I only plug in the 90 amp when i run the on board cummins generator. Im running 3 100ah battle born lithium batts. Is it ok to run both converters at once. I seem to only get about 45 amps of charging power running both or only either one. Also have 300 watts of solar running at the same time. I was thinking I would have around 150 amps of charging power available. Cables from the 90 amp are separate and short straight to the battery bank.

[Butcher]

@SolarPoweredRV So, what you are saying, the higher voltage from the solar would not back feed into the stock converter and get wasted. If that is true [no, I do not have doubts you are wrong] then that is good to know. Thanks for that bit of information. I suspect that a good inverter/charger would certainly have this designed in it.

I do understand if you are plugged in, why do you need fully charged batteries? Well, you do not, but isn't the converters job to keep the batteries topped up and since it only works when it is plugged in, wouldn't they be charged until they are fully topped up? I know when I am plugged in, one of the first things I notice is that the converter fan comes on a few minutes later.

I'm taking my build in steps and I only have a small generator [2k if I recall]. The way I see it is that the generator will only be used to charge the batteries and nothing else. I suspect the inverter/batteries would run everything I would need and most of what I want. If I can keep the batteries in the working range, then I would not need a larger generator. It sounds like your system is similar to my goals.
Fortunately, I camp in places that I don't need A/C, it's certainly not mandatory.

[Butcher]

@xrated, on my quick, dirty, not so informational lithium charging, but certainly controversial test using a stock WFCO converter, after several days [too busy to monitor and just looked at it when I did], I noticed that the converter was not on the float level and the system stopped charging.

I was concerned with that, while trying to figure out how the 53% could be justified. I can see that a stock converter could drop to a float level prematurely and that for certain would give a good reason for the 53% value. I just never saw that.

[SolarPoweredRV]

I have add a PD 90 amp lithium converter to my original (replaced with 60 amp PD lithium converter) I only plug in the 90 amp when i run the on board cummins generator. Im running 3 100ah battle born lithium batts. Is it ok to run both converters at once. I seem to only get about 45 amps of charging power running both or only either one. Also have 300 watts of solar running at the same time. I was thinking I would have around 150 amps of charging power available. Cables from the 90 amp are separate and short straight to the battery bank.

Very interesting issue and the answer will be just as interesting.

Without seeing your installation, I can tell that you have wired your 3 BB batteries in parallel. I am further guessing that the load (both Pos and Neg) is attached to the terminals of a single battery.

As you know, each BB battery has an Internal Battery Management System (BMS). The specifications on your BB batteries limit charging to 0.5C. 0.5C means 50% of the battery's rated draw (100 amps), therefore each battery is limited to 50 amps when charging.

Below, I am attaching a report about wiring batteries in parallel that explores various ways to wire batteries in parallel and indicates what happens to each battery in the string under the different wiring methods.

What is happening in your case is that the battery that is attached to the load is receiving all the charging current and the internal BMS of the first battery is limiting the charging for all three batteries to 50 amps.

To fix this, you need to rewire your batteries using Buss Bars (one Pos and one Neg). You will run the positive cable from each battery to a Buss Bar and then attach the load to the Buss Bar (repeat with the Neg cables). This allows each battery to contribute it's full potential amps to the load (100 amps from each battery) and, more importantly to you, allows each battery to receive up to 50 amps of charging for each battery from your Dual Converters.

Just to make clear the type of Buss Bars I am talking about, I have included a sample photo of the Buss Bar below.

[SolarPoweredRV]

@SolarPoweredRV So, what you are saying, the higher voltage from the solar would not back feed into the stock converter and get wasted. If that is true [no, I do not have doubts you are wrong] then that is good to know. Thanks for that bit of information. I suspect that a good inverter/charger would certainly have this designed in it.

I do understand if you are plugged in, why do you need fully charged batteries? Well, you do not, but isn't the converters job to keep the batteries topped up and since it only works when it is plugged in, wouldn't they be charged until they are fully topped up? I know when I am plugged in, one of the first things I notice is that the converter fan comes on a few minutes later.

I'm taking my build in steps and I only have a small generator [2k if I recall]. The way I see it is that the generator will only be used to charge the batteries and nothing else. I suspect the inverter/batteries would run everything I would need and most of what I want. If I can keep the batteries in the working range, then I would not need a larger generator. It sounds like your system is similar to my goals.
Fortunately, I camp in places that I don't need A/C, it's certainly not mandatory.

I was answering the question posed about using the OEM Converter combined with a Solar System. In that case, the OEM Converter would not top off the batteries, however the Solar System would be able to (providing there is enough Sunshine).

When it comes to the OEM Converter not absorbing [feed back] the higher voltages created by the Solar system, All Converters already do not do this, just consider the higher (and variable) voltages produced by the Tow Vehicles. The Battery(ies) will simply accept the higher voltage and the Converter ignores the higher voltage.

In your case where the Generator (via the Shore Power connection) is the primary method for charging the batteries while boondocking, I would most certainly recommend upgrading the Converter to a Lithium Ready Converter as well as a higher amperage Converter (in the 80 - 100 amp range) to reduce run time on your Generator.

In my response, I mentioned that my Solar System is the primary charging source in my system. The Solar system is the only source I have to charge my batteries to 100%. There are a couple of reasons for this: First, my batteries are Lithium Ion, not Lithium Iron Phosphate (LiFePo4). Consequently, my batteries like to live at less than 100% charge, whereas, LiFePo4 batteries prefer to live at 100% SOC. Different batteries, different charging requirements. When I am plugged into Shore Power my batteries can live quite well at a lower SOC and that is why I set up my system that way. By-the-way, I could set my Inverter/Charger to fully charge my batteries, I have never found the need to do it yet. Second, I have 1,200 Watts of Solar on my roof and the Solar can easily increase the voltage in my batteries to 100% from the lower voltage I have set the Inverter/Charger to, even on a cloudy day.

[LanerC]

Very interesting issue and the answer will be just as interesting.

Without seeing your installation, I can tell that you have wired your 3 BB batteries in parallel. I am further guessing that the load (both Pos and Neg) is attached to the terminals of a single battery.

As you know, each BB battery has an Internal Battery Management System (BMS). The specifications on your BB batteries limit charging to 0.5C. 0.5C means 50% of the battery's rated draw (100 amps), therefore each battery is limited to 50 amps when charging.

Below, I am attaching a report about wiring batteries in parallel that explores various ways to wire batteries in parallel and indicates what happens to each battery in the string under the different wiring methods.

What is happening in your case is that the battery that is attached to the load is receiving all the charging current and the internal BMS of the first battery is limiting the charging for all three batteries to 50 amps.

To fix this, you need to rewire your batteries using Buss Bars (one Pos and one Neg). You will run the positive cable from each battery to a Buss Bar and then attach the load to the Buss Bar (repeat with the Neg cables). This allows each battery to contribute it's full potential amps to the load (100 amps from each battery) and, more importantly to you, allows each battery to receive up to 50 amps of charging for each battery from your Dual Converters.

Just to make clear the type of Buss Bars I am talking about, I have included a sample photo of the Buss Bar below.

Hey, Thanks so much! Im going to do just what you said, that makes total sense!

[Butcher]

There are a couple of reasons for this: First, my batteries are Lithium Ion, not Lithium Iron Phosphate (LiFePo4).

Don't you have Battle Born Batteries?

"For example, lithium iron phosphate (LiFePO4) is popular for replacing 12-volt lead-acid batteries. Lithium iron phosphate batteries have excellent chemical and thermal stability, which makes them safe for rugged applications. Additionally, they have a long life cycle and a high current rating. We use this chemistry in our Battle Born Lithium Batteries."

https://battlebornbatteries.com/what...m-ion-battery/