I keep a pretty tight watch on my batteries via a link 1000... Something interesting has been happening when the batteries are left on the charger solar or shore. While the charger is on it is reading about 13.1v which is the float voltage and the link will show no amp discharge. When the charger is turned off the voltage drops to about 12.3-12.4. If the charger is turned back on the batteries will accept no amp input. Weak batteries? Hold on a minute! If a load is put on the batteries and they are allowed to discharge 75amps or so (440ah bank)and then allowed to recharge to "0" and then the charger is turned off, the batteries will hold 12.6v+. After that if discharged, the realtionship between amps used and voltage readings are wherethey should be based on Casey's book.... What could be happening in the float mode to cause this to happen or am I missing something else? Brian
Float voltage...
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temperature???
The temperature of the battery will affect voltage. A battery will warm up some while being charged. Tom
The temperature of the battery will affect voltage. A battery will warm up some while being charged. Tom
Float V > Battery V
Brian The float voltage is higher than the hold voltage a battery will do when fully charged. A fully charged battery is 12.8 V. Float is 13.1 V > 12.8. You turn your charger off, the batteries revert to 12.8 V which is what the earlier charge and then the 13.1 V float allowed them to get to in the first place. When you restart your charger, there's no input because the batteries are FULL. Read West Marine Advisors and Ample Power Primer in addition to Casey. Stu
Brian The float voltage is higher than the hold voltage a battery will do when fully charged. A fully charged battery is 12.8 V. Float is 13.1 V > 12.8. You turn your charger off, the batteries revert to 12.8 V which is what the earlier charge and then the 13.1 V float allowed them to get to in the first place. When you restart your charger, there's no input because the batteries are FULL. Read West Marine Advisors and Ample Power Primer in addition to Casey. Stu
Acceptance rate
Most manufacturers specify a Bulk Charging Voltage at 14.4V. HOWEVER - 15.2V (or thereabouts) might be better. See the recent discussions at Cruisers’ Forum: http://cruisersforum.com/showthread.php?s=&threadid=1442 http://cruisersforum.com/showthread.php?s=&threadid=1432 Rick is a professional, and offers some interesting information.
Most manufacturers specify a Bulk Charging Voltage at 14.4V. HOWEVER - 15.2V (or thereabouts) might be better. See the recent discussions at Cruisers’ Forum: http://cruisersforum.com/showthread.php?s=&threadid=1442 http://cruisersforum.com/showthread.php?s=&threadid=1432 Rick is a professional, and offers some interesting information.
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I realize that the batteries drop once taken off of float voltage.. And they SHOULD be at 12.6v-12.8v not 12.3-12.4v after resting for 24 hours. 12.3v is the voltage the batteries should be at if discharged a 100ah or so...(based on my bank) My point about "turning the charger back on and the batteries not accepting a charge" was to indicate that the charger had not "misread" the voltage somehow and switched to float mode. Thanks Brian
I realize that the batteries drop once taken off of float voltage.. And they SHOULD be at 12.6v-12.8v not 12.3-12.4v after resting for 24 hours. 12.3v is the voltage the batteries should be at if discharged a 100ah or so...(based on my bank) My point about "turning the charger back on and the batteries not accepting a charge" was to indicate that the charger had not "misread" the voltage somehow and switched to float mode. Thanks Brian
Open Lead acid vs. Sealed AGM
The float voltage of 13.1-13.2 is a good number if you have conventional lead acid batteries, the kind were you can take the caps off and add water. The sealed battery (AGM)should have a float voltage a little higher, about 13.7-13.8. This is from a web page of Professional Mariner, Inc, who made the charger on my Cat 27, a Readiamp 8. http://www.promariner.com I found a very good webpage with instructions on testing a deep cycle battery at http://pacificpowerbatteries.com, they also have a good explaination of surface charge. They say the float voltage for an AGM should be about 13.4-13.5. They are also pretty emphatic about not putting an equalizing charge (the 14.4-15 volts mentioned in one post)on an AGM battery. IMHO if I was to charge a battery in my boat at that voltage, I would monitor the temperature pretty closely. It would tend to outgas pretty quickly and carry acid with the gas, getting onto everything in the battery compartment. Things I just found out about my batteries: Because my charger was set up for AGM batteries, and the guy I bought the boat from put in unsealed lead acid cells, the water has to be topped off every two weeks or so. Even when the batteries are fully charged, the 13.7 volts pushes about 1/2 an amp through each battery, causing gasing and loss of water. If it was 13.2, this wouldn't happen. This has caused sulfation on my battery plates, taking the sulfur out of my sulfuric acid and leaving more water. This has reduced the capacity of my batteries, because the sulphur coats the plates and keeps them from storing or discharging electrons. Adding acid to the water probably won't do me a lot of good, since its the plate area that determines capacity. There are chemicals to remove this, but they don't seem to be recommended by the experts. And there is an expensive system called pulse charging that promises to remove the sulfation, but I am a little skeptical of all their claims. Has anyone on the list used pulse charging on a sulphated battery, or used restore chemicals, and had good success?
The float voltage of 13.1-13.2 is a good number if you have conventional lead acid batteries, the kind were you can take the caps off and add water. The sealed battery (AGM)should have a float voltage a little higher, about 13.7-13.8. This is from a web page of Professional Mariner, Inc, who made the charger on my Cat 27, a Readiamp 8. http://www.promariner.com I found a very good webpage with instructions on testing a deep cycle battery at http://pacificpowerbatteries.com, they also have a good explaination of surface charge. They say the float voltage for an AGM should be about 13.4-13.5. They are also pretty emphatic about not putting an equalizing charge (the 14.4-15 volts mentioned in one post)on an AGM battery. IMHO if I was to charge a battery in my boat at that voltage, I would monitor the temperature pretty closely. It would tend to outgas pretty quickly and carry acid with the gas, getting onto everything in the battery compartment. Things I just found out about my batteries: Because my charger was set up for AGM batteries, and the guy I bought the boat from put in unsealed lead acid cells, the water has to be topped off every two weeks or so. Even when the batteries are fully charged, the 13.7 volts pushes about 1/2 an amp through each battery, causing gasing and loss of water. If it was 13.2, this wouldn't happen. This has caused sulfation on my battery plates, taking the sulfur out of my sulfuric acid and leaving more water. This has reduced the capacity of my batteries, because the sulphur coats the plates and keeps them from storing or discharging electrons. Adding acid to the water probably won't do me a lot of good, since its the plate area that determines capacity. There are chemicals to remove this, but they don't seem to be recommended by the experts. And there is an expensive system called pulse charging that promises to remove the sulfation, but I am a little skeptical of all their claims. Has anyone on the list used pulse charging on a sulphated battery, or used restore chemicals, and had good success?
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