What Needs to be Changed When Upgrading to a Lithium Battery System?
There are 5 products to keep in mind when upgrading your battery bank from lead acid to lithium in your caravan, 4WD or boat. Lithium batteries offer faster charging, longer runtime, longer life, and weigh less than the equivalent size lead-acid battery. However, it’s essential to understand that lithium batteries also feature significant differences compared to lead-acid batteries. Safely charging the new lithium battery system requires all charging devices to use a new charge profile that explicitly matches the lithium battery. Additionally, the electrical system must be protected from load dumps and voltage spikes. Some additional pieces of equipment will be required:
240V Battery Charger- A 240V battery charger with programmable charge settings that matches the lithium battery. Lithium batteries have superior charge acceptance over lead acid batteries so it's also worth considering a higher charge current, around 0.2C or 20% of the battery bank's capacity. I.E for a 200Ah lithium battery bank a 30-40A AC charger would be well sized.
Solar Charger- If you have solar panels or a wind turbine, they require a charge controller with programmable charge settings matching the lithium battery. Older charge controllers don't usually have a lithium setting, so you might need to upgrade to a newer charge controller (such as Victron MPPT) that will feature a lithium setting.
DC-DC Charger- A DC-DC charger with programmable charge settings matching the lithium battery to regulate voltage and control the flow of current between the alternator and lithium batteries. The alternator is the primary method of charging the battery system for boats and caravans when away from 240V power.
Shunted Battery Monitor- Unlike your lead acid batteries you can't accurately measure your lithium batteries state of charge from voltage alone as they'll generally sit above 13.0V. A shunted battery monitor will accurately measure your batteries voltage, % of charge, time remaining and much more! See our Victron BMV-712 or Victron SmartShunt range in the "Monitoring" section for more information. Note: If your lithium battery has a built-in Bluetooth monitor already then this would be an optional extra.
Low voltage disconnect / Battery Protect- The Low voltage disconnect will switch off your loads before it drains your battery dead flat, which prolongs battery life. This is especially required for the Victron Lithium Smart batteries. It can also be used as a "charge" protect. (See the Victron BatteryProtect Data sheet for more information). If your lithium battery has a built-in BMS then this is an optional extra as it is already built into the battery. You can still use a BatteryProtect as "extra insurance" so that the BatteryProtect will switch your loads off before the BMS switches your battery off, meaning your chargers can still charge the battery.
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