AnswerID: 285068 Submitted: Saturday, Feb 02, 2008 at 07:53
Member - Tony W (VIC)
replied:
I reckon there are about 4 types on the market. Before deciding look up battery voltage and battery capacity. the differece between a full battery ( of charge) is 12.7 full verses 11.9 for 40% which is as low as you should usually go.
1)Bar Graph LED ones like at Jaycar and Dick Smith for $10 - 30
These look good and make you feel good but don't really tell you much other than emptyish, or fulish. I had one of these and basically decided I am wasting my time
2)Voltmeter - Panel meter digital ( or good analogue). From Ebay , Jaycar, Pirhana, Dick Smith Derek etc $20 up
Good and accurate, however you must remember the relationship between voltage and charge which can vary under different conditions. Anything over $30 and you are wasting money.
Minimum you should get in my view.
3)Digital or claibrated LED Bar graph meters with some kind of capacity indication and alarms. Eg Opposite lock chargemaster,
ABR Battery monitor. $120 - $200
Easier to monitor without remembering voltage relationships. If you need to rely on charged batteries these are great.
4)Proper full on battery monitoring with charge in / out measurements. You will know everything that is going on in your batteries. $300 - 800 Eg NASA battery Monitor from
ABR. These are brilliant.
After having researched this I have found that the most important thing is to understand how batteries work and what the voltages mean. I used to think a 100AH Deep cycle battery would reliably give me 1 A for 100 hours or say 2 A for 50hours but in reality if I get half that I am doing well. ( 90% charged and discharge to 40%).
Hope this helps.
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