I've used both a Xantrex Link 2000, and a Mastervolt MICC to monitor battery status and they're both useless. Both of these devices count amp hours, but they quickly become out of sync with the actual status of the battery. Right now the Mastervolt MICC reports 25.5v and a 33% state of charge! I always end up using the morning voltage when there is very little current draw as the indicator of battery status but I know that's also not very accurate.
I have a 24v 1,000 ahr battery bank that is charged from solar, wind and the engine alternators which can bring it to 80-90%. About once a month it gets fully charged and topped up via shore power.
I came across a "not counting amp hours" solution at www.smartgauge.co.uk
Does anyone have experience with this device, or with any other device that accurately tracks battery charge status?