OK Ed, here's the new thread for the battery experts. My two Trojan 8D house batteries (3 years old) don't seem to hold their charge very well. Leave the dock with a full charge from a smart charger. Get to destination, drop the hook, and 18 hours later the voltage is down to 12.2 with only -75 amp/hours out of the system. The refrigeration compressor won't start at that voltage. (Is this a malfuction?) I think I should be able to get to at least -200 amp/hours (50% of capacity) and still have about 12.6 volts. I have equalized the batteries several times, and other than make a mess, it doesn't seem to do much of anything. Are my expectation reasonable? I think I'm carrying around a hundred plus pounds of battery for nothing. Please advise. Thanks. Larry W.
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A couple of thoughts...
Larry, Are you sure that the batteries are being fully charged? What is your charger configuration? Do you have a dc system monitor with amp-hour measurement? Do you have deep cycle batteries? I was surprised to find that Destiny had two 4D starter batteries as the house bank. I have been waiting for them to die for two years, and I'm finally getting my wish....
Even with two 8D's I would be very hesitant to run a refrigerator for any length of time off the batteries alone. What current does the refrigerator draw? If the average current is six amps, 18 hours use would consume about 110 amp/hours.
Larry, Are you sure that the batteries are being fully charged? What is your charger configuration? Do you have a dc system monitor with amp-hour measurement? Do you have deep cycle batteries? I was surprised to find that Destiny had two 4D starter batteries as the house bank. I have been waiting for them to die for two years, and I'm finally getting my wish....
Even with two 8D's I would be very hesitant to run a refrigerator for any length of time off the batteries alone. What current does the refrigerator draw? If the average current is six amps, 18 hours use would consume about 110 amp/hours.A couple more thoughts
You might want to load test the batteries to make sure the full charge is really full. Beyond that you might also want to do an energy audit of your usage. I'm not sure what you are monitoring with, perhaps a Link 2000. If so, I believe there are settings in the Link that might be out of adjustment for your battery brand, type, etc. Anotherwords, maybe -75 amps isn't really -75 amps. An audit should help to verify if the expected usage matches what the gauge is telling you. We have two 4D's in our 356. We run the refrigerator, radar, chartplotters, whatever we want and come no where near 50% discharge in that amount of time. If we stay out for a few days then we need to conserve some and think about engine run time to put it back. Let us know how it turns out. Dan Jonas (S/V Feije II)
You might want to load test the batteries to make sure the full charge is really full. Beyond that you might also want to do an energy audit of your usage. I'm not sure what you are monitoring with, perhaps a Link 2000. If so, I believe there are settings in the Link that might be out of adjustment for your battery brand, type, etc. Anotherwords, maybe -75 amps isn't really -75 amps. An audit should help to verify if the expected usage matches what the gauge is telling you. We have two 4D's in our 356. We run the refrigerator, radar, chartplotters, whatever we want and come no where near 50% discharge in that amount of time. If we stay out for a few days then we need to conserve some and think about engine run time to put it back. Let us know how it turns out. Dan Jonas (S/V Feije II)
Batteries
Larry Last weekend I checked the electrolyte level and the hydrometer readings on each cell, since our almost four year old batteries never gave us any problems, and rarely needed water. In addition to, and maybe even in spite of, all the Link measurement stuff, check each cell. Could be that one cell just fried and is taking down the whole house. Stu
Larry Last weekend I checked the electrolyte level and the hydrometer readings on each cell, since our almost four year old batteries never gave us any problems, and rarely needed water. In addition to, and maybe even in spite of, all the Link measurement stuff, check each cell. Could be that one cell just fried and is taking down the whole house. Stu
Check wire
Check the wire connections/wire size to the frig compressor. Bad connection/small wire could increase voltage drop to the point where even with fully charged batteries, compressor is only seeing 10.5 V which is where they usually have the cutoff on the compressors.
Check the wire connections/wire size to the frig compressor. Bad connection/small wire could increase voltage drop to the point where even with fully charged batteries, compressor is only seeing 10.5 V which is where they usually have the cutoff on the compressors.
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