ksanders
Moderator Emeritus
Yesterday I replaced my 9 year old house battery bank.
The new bank consists of four Crown CR430 Flooded Lead Acid Batteries which are a L16 form factor, making for a 860 amp hour house bank.
In the afternoon I topped off the charge, and calibrated my Xantrex link pro battery monitor.
Right before bed I turned off all shore power. At that time I was drawing approx 40 amps.
I let the batteries drain to 50% charge, and recorded the voltages under load along the way. Here are a highlight of the results
-345 amp hours, 60% charge 34 amp draw, 11.73 volts
-430 amp hours, 50% charge 33 amp draw, 11.57 volts
These voltage reading were taken under load, as my battery bank was and always is supplying my house loads.
The Crown Battery manufacturers specification for under load at a 20 hour rate is 11.64 volts at a 50% charge. They say that a battery bank needs to be cycled 20-25 times to get up to its full capability.
Crown also indicates that at 0 charge the bank will read 10.5 volts under load at a 20 hour rate.
This was very interesting data to gather, and I hope it helps others determine when to replace their house bank. I will be recording the results in my log book and using it as a future reference.
This should also help dispel many of the myths floating around the boating world about house battery voltages. There are many charts and graphs out there and pretty much every one of them call for reading battery voltage with no load, which never happens in a real working boat, and the house bank is always in use. Crown and Trojan are the only manufacturers that I have found to present real world voltage data under load.
The new bank consists of four Crown CR430 Flooded Lead Acid Batteries which are a L16 form factor, making for a 860 amp hour house bank.
In the afternoon I topped off the charge, and calibrated my Xantrex link pro battery monitor.
Right before bed I turned off all shore power. At that time I was drawing approx 40 amps.
I let the batteries drain to 50% charge, and recorded the voltages under load along the way. Here are a highlight of the results
-345 amp hours, 60% charge 34 amp draw, 11.73 volts
-430 amp hours, 50% charge 33 amp draw, 11.57 volts
These voltage reading were taken under load, as my battery bank was and always is supplying my house loads.
The Crown Battery manufacturers specification for under load at a 20 hour rate is 11.64 volts at a 50% charge. They say that a battery bank needs to be cycled 20-25 times to get up to its full capability.
Crown also indicates that at 0 charge the bank will read 10.5 volts under load at a 20 hour rate.
This was very interesting data to gather, and I hope it helps others determine when to replace their house bank. I will be recording the results in my log book and using it as a future reference.
This should also help dispel many of the myths floating around the boating world about house battery voltages. There are many charts and graphs out there and pretty much every one of them call for reading battery voltage with no load, which never happens in a real working boat, and the house bank is always in use. Crown and Trojan are the only manufacturers that I have found to present real world voltage data under load.
