Ericson 27 1976 "Lotus Flower"
More Batteries;
After initial operations with the existing prop and minimal battery capacity (four group 27 AGM’s) I added four group 31 AGM batteries as a separate 48 volt bank for longer range and redundancy. This brought the battery storage up to about 200 amp hours at 48 volts total. There are valid arguments against the two separate banks system I chose and having all eight 12 volt batteries connected in series/parallel as one bank.
The main issue is the range loss to the Peukert Effect or Law. As I understand the Peukert Law (and I’m no electrical engineer!) a 200ah battery bank will have more usable amp hours at the same current requirement compared to two 100ah banks.
I should say here that there are EP systems operating with 100ah capacities - four 12 volt batteries and they are working fine.
For my confidence having a “spare” battery bank is worth the small loss in range. If one battery in a bank goes bad it pulls the entire bank down and the result is reduced range and eventually possible failure of the rest of the batteries in the bank. Shortly after adding the second bank one of the new group 31 AGM’s started to fail. It would not hold as high of a charge as the other three batteries. The battery company honored the warranty and sent me a new battery.
At this point in the repower I had one 48 volt charger that would be switched between the two banks. I liked this setup as it was simple and I was able to charge two banks with one charger. Unfortunately the 48 volt charger had trouble with the newer battery, even though it was the same exact battery as the others in the bank. The batteries would charge at wildly different voltages and never become balanced.
Another charger option for the four battery bank is a “quad” charger which is really just four battery chargers in one case. My hope was that the separate chargers would effectively balance the bank. It worked beautifully. Now I have two chargers aboard Lotus Flower with the up side being that shore power can charge and maintain both banks at the same time - and that redundancy thing.
After initial operations with the existing prop and minimal battery capacity (four group 27 AGM’s) I added four group 31 AGM batteries as a separate 48 volt bank for longer range and redundancy. This brought the battery storage up to about 200 amp hours at 48 volts total. There are valid arguments against the two separate banks system I chose and having all eight 12 volt batteries connected in series/parallel as one bank.
The main issue is the range loss to the Peukert Effect or Law. As I understand the Peukert Law (and I’m no electrical engineer!) a 200ah battery bank will have more usable amp hours at the same current requirement compared to two 100ah banks.
I should say here that there are EP systems operating with 100ah capacities - four 12 volt batteries and they are working fine.
For my confidence having a “spare” battery bank is worth the small loss in range. If one battery in a bank goes bad it pulls the entire bank down and the result is reduced range and eventually possible failure of the rest of the batteries in the bank. Shortly after adding the second bank one of the new group 31 AGM’s started to fail. It would not hold as high of a charge as the other three batteries. The battery company honored the warranty and sent me a new battery.
At this point in the repower I had one 48 volt charger that would be switched between the two banks. I liked this setup as it was simple and I was able to charge two banks with one charger. Unfortunately the 48 volt charger had trouble with the newer battery, even though it was the same exact battery as the others in the bank. The batteries would charge at wildly different voltages and never become balanced.
Another charger option for the four battery bank is a “quad” charger which is really just four battery chargers in one case. My hope was that the separate chargers would effectively balance the bank. It worked beautifully. Now I have two chargers aboard Lotus Flower with the up side being that shore power can charge and maintain both banks at the same time - and that redundancy thing.
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