Installing Lithium with older Charging Systems

Installing Lithium with older Charging Systems





This technical article is designed to give value to the reader knowledge on upgrading to Lithium batteries but keeping older charging systems. 

If you have AGM batteries and an AGM charging system and are looking at upgrading your batteries, this is a practical and lower cost way of upgrading.

Lets say you have this setup on your AGM batteries:

  • 2 x 100Ahr to 130Ahr AGM batteries
  • Redarc BCDC 1240 Charger
  • Ctek 30A 240V Charger (with quiet night mode)

Here is our guidance with the reasons why that follow:


  • Redarc BCDC 1240 Charger
  • Ctek 30A 240V Charger (with quiet night mode)


  • 1 or 2 x 125Ahr Lithium with Victron Mesh Enabled feature inbuilt
  • 1 x Victron Smart Solar 10/15/20A depending on the size of your solar panel system


  • The Exisiting Redarc BCDC will output 14.4V in bulk mode (if AGM has been selected). This will raise the Lithium battery to 95% charge quickly and over a very long time eventually get to 99%. Holding at this charge in the event that nothing else is connected, will not damage nor reduce the cycle life of the lithium batteries.
  • Providing the Ctek charger doe not have an automatic “de-sulphate or eualization” mode, it will perform in  a similar way to the DC to DC. Most of the Ctek chargers require a manual “press” to activate the “de-sulphate” mode. So avoid selecting this and there is no impact on the batteries.
    If it does have an automatic “de-sulphate”, you will have to replace it.
  • The Victron Smart Solar communicates directly via Bluetooth mesh Network with the Safiery Lithium battery and reads the exact battery voltage via bluetooth. It then ramps up the smart solar output volatge and holds it until the Lithium Batteries get to 100%.
  • The Victron Smart solar will operate in addition to the Readarc BCDC so you get charging from both sources at the same time.

Are they other benefits?

  • Yes, the Victron Smart Solar is an ultra fast MPPT charger and out-performs the Redarc BCDC in solar mode by at least 20% in variable weather. It is perfectly coupled to Lithium batteries.
  • You will read the solar charging history AND the battery voltage on the Victron Smartphone App. This is not possible on Redarc , Enerdrive or Intervolt systems. 

What if I dont have Redarc?

  • Any DC to DC that has an AGM profile applies with the same logic above. Other brands are Projecta, Intervolt, Sterling and Enerdrive.
  • Likewise with the 240V charger…Other brands are Projecta, Intervolt, Sterling and Enerdrive.

What are the displays for older BCDC before and after upgrade?

You get excellent histroy and trend data on solar, something you wont see in other brands:

Two Victron Smart Solar examples :

victron smart solar history results on smartphone victron smart solar history no 2 results on smartphone