The “Impossible” Battery

I don’t know if you have come across this battery or the claims being made by Lifeline, the manufacturers.

  • Thick plates for deep cycle use
  • No maintenance required ever
  • Double the cycles than a standard Gel battery
  • Can be mounted in any orientation
  • No venting
  • Recharges 30% faster
  • No upper charging level limit
  • 5 year warranty

What caught my attention apart from the price (less than GEL) and the charging claims – which by the way makes them Lifeline batterymore suited to solar panel charging systems…was the safety aspect – “No Venting”. When batteries are mounted for bow thrusters or an anchor windlass they are often sited under the bed or at least somewhere within the fore cabin. So any improvement in safety here would be of interest.

A conventional electrical system would consist of two battery banks (one for engine starting, the other for house loads), a blocking diode split charger and alternator controller. The diode would split charge between the two battery banks while the alternator controller would develop high charging voltage to ensure rapid battery charging.

With this Lifeline system you could have the two battery banks and then a VSR (Voltage Sensitive Relay) that’s all. The system would work in exactly the same way and would also charge as quickly. While the initial battery cost is higher than conventional batteries, the expensive split charger and alternator controller isn’t needed. What’s more, the system would be easier, and less expensive overall, to install.

Due to Lifeline’s low internal resistance, response to high power surge demands on

inverters is better matched. Conventional thick plate lead/acid batteries or gel cells

take time to respond to, and deliver high currents; Lifeline provides high current

instantly preventing the surge from motors, power tools etc tripping out the

inverter’s low battery cut-out (this often happens even if the conventional battery

bank isn’t flat). Leading inverter manufacturers recommend Lifeline for professional

installations of their products.

Bow thrusters
Bow thrusters require high surge power to start (in the same way as inverters,

above) making Lifeline entirely appropriate for this application. However, how long

does a bow thruster run for? Typically, 3 minutes maximum. Say the thruster was

rated at 4kW at 12V (which equates to around 333 amps); Remember though that

this is an hourly rate (333 amps), so divide it by 60 to get an approximate 5.5 Ah per


pdfDownload the Merlin Split Charging Guide here for more info.

To download my free Excel spreadsheet showing how to assess your power usage while at marina, anchor, or sailing please click here


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