Upgrading to lithium battery

DIY
1

Hi everyone

I’d like to upgrade my current 105ah lead acid leisure battery to lithium.

I currently have a SmartSolar charge controller MPPT100/30 and BMV-712 Smart battery monitor.

What else will I need please?

TIA

2

You probably mean LifePO4 or LFP in short. Li-ion is rare on yachts. You’d need a good charger which is capable of charging your LifePO4 batteries with a LFP profile. Normally, modern Victron charges have these profiles and they can be chosen (in case of the bluetooth chargers) or programmed to do so. The Victron BMV712 has bluetooth and a shunt placed at the battery. So that one is capable of measuring the new batterie voltage more accurate than the charger does, because the charger only knows the voltage it self delivers via cables to the battery. Because of that, in case of LFP it is important to connect your BMV to your Victron charger via the (bluetooth) VE network. Then your charger sees the correct battery voltage and knows when it has to stop bulk charging and go to absorption. Last; (I guess this setup is for a boat) you might need or might need not a DC DC converter between the dynamo and the LFP battery. This is because the internal resistance of the LFP battery is so low that your dynamo will run hot. The DC DC converter will manage that the dynamo does not deliver it’s full power. But, consider that you might need not to connect your dynamo to your LFP battery, because it does not make a lot of sense. Charging by dynamo might not be necessary anymore because of the large capacity of the LFP battery. Next to that you also have a solar panel which can charge during anchoring, docking and sailing.

3

What else you need depends on what you want to do with the system.

Upgrade by definition means you already have a working system in place that you are altering. In your case with a fairly simple swap.

it should be as simple as

  1. Replace the battery physically,
  2. update components and
  3. reprogram with the lithium profile and voltages.
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4

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