There are numerous variations. “Heavy Duty” batteries (“car batteries”) will provide huge currents for very short periods, so they are ideal for engine starting, but they quickly deteriorate if they are discharged by more than about 30% of their capacity. “Deep cycle” or “traction” batteries are much better at withstanding deep discharges, but cannot provide such large currents, so they are better for supplying domestic power. “Leisure” batteries are an economical compromise between the other two types.
These “conventional” lead-acid batteries, supplying power to a vessel’s main fixed VHF set, can be conveniently kept at a reasonable state of charge by the boat’s engine-driven alternator. It isn’t perfect, but it is a common and very practical solution.
More sophisticated versions of lead-acid batteries are filled with an acid gel or acid-impregnated mats instead of the liquid acid that is used in a typical car battery. This makes them less susceptible to spills or damage, but in most cases reduces their ability to produce very high currents (such as for engine starting) or to accept rapid recharging.
The chargers for the more sophisticated types of lead acid battery should be built into the boat when the batteries are installed. They may provide a slower rate of charge than normal, but they are designed to make sure that the battery really is fully charged.
NiCad (Nickel Cadmium) batteries are compact and rather lighter than lead acid batteries, but they are more expensive, so they are mainly used in small sizes to power portable radios. They are potentially able to withstand thousands of charge/discharge cycles, but they are inclined to lose their charge gradually when stored and their ability to accept a full charge quickly deteriorates due to the so-called “memory effect” if they are subjected to “top-up” recharging without having been fully discharged. They produce a slightly lower voltage than alkaline batteries, so some equipment designed to accept alkalines will not work with NiCads.
NiMH (Nickel Metal Hydride) batteries are rechargeable, and have a higher capacity than NiCads of similar size and weight, as well as being able to deliver more current. They don’t last quite as long as well-maintained NiCads, but the “memory effect” is very much less significant. Unfortunately, they produce the same low voltage as NiCads, but they are more expensive and are inclined to self-discharge even when not used.
Lithium Ion batteries are rechargeable. For a given size and weight, they store more power than any other readily-available battery, but are very much more expensive, and very much more susceptible to overcharging.
Recharge NiCads only when they are flat.
Top up other rechargeables whenever you can.
Don’t overcharge any rechargeable, but particularly not a Lithium Ion.
Don’t recharge alkalines or lithiums.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92
