The difference between wire and cable

Double Insulated wire can be referred to as Insulated (protective layer directly surrounding the conductors) and Sheathed. The outer protective layer which encapsulates 1, 2 or more conductors also changes a single wire to a multiples of wire referred to as cable. If 2 conductors the cable is referred to as 2 core. 3 insulated wires would be 3 core cable etc

Active BMS

Active battery management means the BMS is always recording data, therefore you can record lifetime operation and cycle-life. Passive only manages balancing when the battery is on, for the time it’s off the cells will continue to self-discharge and could therefore drop below minimum voltage levels without warning or alert.

One downside to an active management system is the need to constantly replace the energy being used by the BMS to monitor the batteries health. This isn't ideal in a boat if only used seasonally, but would be perfect for an off-grid solar system connected to solar panels which would recharge the battery daily.

How to test a solar panels output

A single Solar Panel can have its positive and negative cables connected together to test the total max current (Amps) generation without damage.

You can also insert a voltmeter directly into the ends of a solar panel to check its voltage, but its voltage will change depending on how much light the panel receives so it's really only used to check V.O.C. (Voltage Open Circuit) and that the panel doesn't have a fault.

What is a BMS

B.M.S. stands for Battery Management System. But a cheaper battery solution which includes a BMS might actually refer to a Battery Monitoring System.
A management system can isolate a cell or disconnect a battery pack if an error is detected. A monitoring system might show an error code in software, or maybe an LED will flash or an audible alert. But if you aren’t able to respond to what’s happening immediately the result could be catastrophic.

Secondary Batteries

Did you know all rechargable batteries are referred to as secondary batteries. A primary battery can't be recharged. i.e. a watch battery. Batteries made using acid and lead are all approx. 2v so a 12v battery is actually a combination of 6 cells in series making a 12v battery. Our 16 volt batteries are 8 cells, 6 volt are 3 cells etc etc.

Why would someone ask the voltage of a battery?

Well, a 12-volt battery is made up of six 2v cells, and a 6v battery is 3 cells. With Flat plate AGM chemistry batteries each cell is 2.14v so a 12v battery is actually 12.84 (or almost 13 volts).

When someone estimates a batteries state of charge they check the voltage and as a rough guide reduce 25% of a batteries capacity by 0.25v. So a completely flat battery is approx 11.84 volts and 50% capacity is approx 12.34 volts - these voltages are taken without any discharge load on the battery.

These voltages per cell aren't exactly correct, as many types of lead acid batteries like flooded (calcium, maintenance-free), or GEL have slightly different characteristics therefore changing the battery's potential output but they serve as a guide.

A flat battery is not zero volts, technically all manufacturers will use a figure in the 10-11 volt range with parameters/conditions of temperature which will vary the actual figure But the thing to take away from this is a lead acid battery has no usable capacity below 10 volts so this is your base number when it comes to the health of your battery. Furthermore, a battery below 2 volts will rarely recover to fully charged unless it is brand new. Capacity can be dramatically reduced if a battery is left for a few weeks in a discharged state.

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