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Old 09-27-2021, 05:15 PM   #1
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Lithium batteries

I have searched for specific information with no satisfactory results. If I am replacing the house lead acid batteries with lithium batteries, where is the best place to install and connect the DC to DC charger? Close to the alternator or in the battery box? Iím looking to install 600 AH of batteries. Looking closely at Dakota Lithium but also a few others.
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Old 09-27-2021, 05:16 PM   #2
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2021 36D7 GT7.
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Old 09-28-2021, 07:09 AM   #3
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If I understand it correctly, the DC-to-DC converter is a device needed to increase the charging voltage to a higher level than is produced by the engine alternator. That's because lithiums need a higher charging voltage than lead acid batteries in order to be charged fully.

The DC-to-DC converter also can reduce the massive draw of current from the engine alternator needed to charge a nearly dead or dead lithium battery. That's because a dead lithum battery, due to its low internal electrical resistance, can appear to be almost a dead short to the alternator. This avoids possible damage to the alternator and associated circuitry.

If those are correct then the phrase "massive draw of current" means the further you place the DC-to-DC converter from the lithium batteries, the thicker the cables from the DC-to-DC converter to the lithium batteries must be.

That would get my vote to put it in the battery box. In addition, the battery box will have a more stable operating environment with regard to water incursion and temperature swings due to the engine.

I do not have lithium but I've been trying to learn.

FWIW,

Ray
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Old 09-28-2021, 06:07 PM   #4
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Quote:
Originally Posted by NXR View Post
If I understand it correctly, the DC-to-DC converter is a device needed to increase the charging voltage to a higher level than is produced by the engine alternator. That's because lithiums need a higher charging voltage than lead acid batteries in order to be charged fully.

The DC-to-DC converter also can reduce the massive draw of current from the engine alternator needed to charge a nearly dead or dead lithium battery. That's because a dead lithum battery, due to its low internal electrical resistance, can appear to be almost a dead short to the alternator. This avoids possible damage to the alternator and associated circuitry.

If those are correct then the phrase "massive draw of current" means the further you place the DC-to-DC converter from the lithium batteries, the thicker the cables from the DC-to-DC converter to the lithium batteries must be.

That would get my vote to put it in the battery box. In addition, the battery box will have a more stable operating environment with regard to water incursion and temperature swings due to the engine.

I do not have lithium but I've been trying to learn.

FWIW,

Ray
I have not seen any problem with charging my Battle Born batteries from the alternator. There is a 1 AWG cable coming from the chassis battery to my Battery Control Center. Voltage drop of the 1 AWG limites the load on the alternator.

I have a been using the alternator for over 2 years to charge my Battle Born batteries. It is nice to get 90 amps of charge as I drive down the road. In addition, I also run my propane/120 fridge on 120 while I drive.

I did have to modify the BCC SDC-107A for the higher charge voltage of Lithium.
see: How to adjust SDC-107A BCC for Battle Born batteries. (10-23-2019, 01:30 AM)

I put over 5,000 mile on my FR3 this year and did not spend one night in a campground. I only stopped at campgrounds for fresh water and a dump.

Boondocking 9-12-2021 @ Mile 108 on Steese Highway (100 miles North East of Fairbanks, Alaska.)
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Samlex EVO-3012 Inverter/Charger | 600ah Battle Born LiFePO4 | Victron BMV-712 & MPPT 100/50 | 800W Renogy Solar | Fan-Tastic Fans | Blue Ox TruCenter | SnapPads | SumoSprings | Koni Shocks | RVLock
Solar Power & Battle Born batteries
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Old 09-28-2021, 06:51 PM   #5
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Where is your BCC located?
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Old 09-28-2021, 07:49 PM   #6
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rk
Where is your BCC located?
In the battery compartment. I had a RV customizer enclose it on three sides.


BCC before conversion to Lithium (Feb. 18, 2018):
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Enclosed battery compartment for six Battle Born Batteries:


After 600ah of Battle Born Batteries:
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Samlex EVO-3012 Inverter/Charger | 600ah Battle Born LiFePO4 | Victron BMV-712 & MPPT 100/50 | 800W Renogy Solar | Fan-Tastic Fans | Blue Ox TruCenter | SnapPads | SumoSprings | Koni Shocks | RVLock
Solar Power & Battle Born batteries
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Old 09-28-2021, 08:29 PM   #7
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Forest River changed away from the SDC-107A BCC to one by Precision Circuits sometime in the 2019 model year. Since you have a 2021 you will have the Precision Circuits one.

Ray
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Old 09-29-2021, 11:21 AM   #8
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Forest River changed away from the SDC-107A BCC to one by Precision Circuits sometime in the 2019 model year. Since you have a 2021 you will have the Precision Circuits one.

Ray
So is there a way to adjust it or since it is newer technology will it automatically adjust? Iíve looked at it and I donít see where it can be adjusted like the old one.
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Old 09-29-2021, 01:50 PM   #9
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So is there a way to adjust it or since it is newer technology will it automatically adjust? Iíve looked at it and I donít see where it can be adjusted like the old one.
It has nothing to do with the amount of charging, just the monitoring of the voltage and battery switching that I know of.

You likely have the Progressive Dynamics PD9270 Converter, a 70-amp unit. If so, you may need to charge the converter to their lithium-capable unit. See https://www.progressivedyn.com/lithi...acement-units/ for more information. That's only if you need to charge the lithium batteries from shore power or the generator.

Precision Circuits (BCC) contact info: https://www.precisioncircuitsinc.com/contact-us/

Progressive Dynamics (converter) contact info: https://www.progressivedyn.com/contact/

Good luck,

Ray
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Old 09-29-2021, 08:31 PM   #10
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So is there a way to adjust it or since it is newer technology will it automatically adjust? Iíve looked at it and I donít see where it can be adjusted like the old one.
You just need replace your BIM with a LiFePO4 Battery Isolation Manager (BIM225Li).


The LiFePO4 Battery Isolation Manager (BIM) monitors voltage and connects batteries when needed. Under normal charging conditions, the BIM will connect for 15 minutes every 35 minutes. That means that the BIM will connect for 15 minutes, disconnect for 20 minutes, and repeat this cycle until the coach battery is charged.

If the coach battery resting voltage exceeds 13.4 V then the BIM will disconnect. A resting voltage greater than 13.4 V indicates a fully charged battery. Note that ďresting voltageĒ means that no current is flowing to the coach battery.

The BIM will disconnect if the alternator voltage exceeds 14.4 V. This protects the coach battery from overcharging. The LiFePO4 Battery Isolation Manager will disconnect if the voltage difference between the alternator and the coach battery is less than 0.1 V. If the voltage difference is too low, then there is a negligible charging current, and no need to connect to the coach battery.

The BIM will disconnect if the alternator voltage drops below 13.3 V. If the alternator voltage is too low, then it cannot adequately charge the coach battery, so there is no reason to connect.
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2018 FR3 28DS | Boondock 99% of the time
Samlex EVO-3012 Inverter/Charger | 600ah Battle Born LiFePO4 | Victron BMV-712 & MPPT 100/50 | 800W Renogy Solar | Fan-Tastic Fans | Blue Ox TruCenter | SnapPads | SumoSprings | Koni Shocks | RVLock
Solar Power & Battle Born batteries
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Old 09-29-2021, 08:59 PM   #11
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If he does not replace the converter he'll get the voltages shown in the attached pic for the PD9200 series. He may not need to charge from shore power or generator, though.

Unfortunately Progressive Dynamics does not publish a similar graph for their 9100L lithium converter.

I guess some people have purchased the optional "pendant". It plugs into the converter and you can use it to change the converter to any mode when desired. I'd read that some people are using their OEM PD9270 converter with lithium and using the pendant to kick the converter back into Boost mode to get the higher voltage when needed for charging.

Ray
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