Lithium implementations A comparison between different implementations

Standard lead-acid installation

Standard lead-acid installation
Standard lead-acid installation

This drawing is provided for comparison. Note that usually charge sources and consumers are added at random somewhere on the single power bus (red wire). There is no separation between charge sources and consumers because there has never been a reason to do so.

Lithium only, no disconnectors, voltage based regulation

Drop-in lithium replacement
Drop-in lithium replacement

This is also called a "drop in replacement" as no modifications are carried out. Note that the lithium battery may have a BMS, but it is unable to offer much protection (if any at all) because it is unable to disconnect the battery in case of overcharging or overdischarging. Don't get lured into the false notion that the battery may have an internal disconnector. It doesn't, and if it had one, your equipment would fry at the moment the BMS activates the disconnector while the alternator is running.

Advantages

Disadvantages

Lithium only, overdischarge protection

Lithium overdischarge protection
Lithium overdischarge protection

Advantages

Disadvantages

Lithium only, overdischarge proctection, charge termination with interruptor

Lithium overdischarge protect, charge term. by disconnection
Lithium overdischarge protect, charge term. by disconnection

Advantages

Disadvantages

Lithium only, overdischarge proctection, charge termination by communication

Lithium overdischarge protect, charge term. by communication
Lithium overdischarge protect, charge term. by communication

Advantages

Disadvantages

Lead-acid/Lithium hybrid

Lithium/Lead-acid hybrid
Lithium/Lead-acid hybrid

Advantages

Disadvantages

Conclusion

A lead-acid/lithium hybrid implementation clearly offers the most advantages.

Despite its clear advantages, the lead-acid/lithium hybrid implementation is relatively unknown. There might be a few reasons for this:

We hope to bring the advantages from lead-acid/lithium hybrid installations more into the well deserved spotlight. Read more about it on our article about lead-acid/lithium hybrid systems.


Comments

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So, when the lithium pack switches off because of low voltage, how does it recognize that it is ok to switch on again? Manually? If you have two circuits (charge and discharge) like usually with LF packs, you will need to redesign a lot.
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We both seem to have adopted exactly the same approach. I too use esp8266 and wireless connection for everything including remote displays, web interface, remote monitoring, etc etc.i have the hybrid BMS as a stand alone unit that can perform all required protection and control of the battery environment and that communicates via MQTT with a Pi and direct to other esp control units including proportional dump load control and various other power control and optimising systems. I think hybrid rocks!
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Dank je wel voor een zeer interessant artikel!
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Frans, finally someone who sees a hybrid system with the same view! I have been struggling with some of the same questions, even the same thoughts about hardware for a BMS. I would enjoy hearing more as you move forward, and could possibly work on the Pro a bit. I am not an EDA expert, but I have worked with it a bit.
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Frans we zijn zelf bezig met het voorbereiden van een li ion verhaal. Wat ons nog niet duidelijk is, is hoe je omgaat met je alternator. De meeste alternatoren branden door als ze li ion laden zonder dat er een regeling is in functie van de temperatuur ten gevolge van de hoge laadstroom? Hoe vangt jouw systeem dat op? Voor ons is juni 2021 of 2022 de vertrekdatum en hopen we jullie ergens in de pacific nog te ontmoeten. Bert (schip: Evarne)
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