curious about battery charger specs

[rgarrison@gmail.com]

I recently bought a used Cat 30. There is a 5 amp battery charger installed charging 3 batteries. It has been recommended I upgrade to a 20 amp. by a well meaning friend.

Curious, is he right? Seems that the output current would only impact recharge time.

I would appreciate any thoughts...if not necessary I would like to budget the money to other upgrades.

 

[Stu Jackson]

You might want to get familiar with the online West Marine Advisors, also found in the paper catalogs.

Like this one:

http://www.westmarine.com/webapp/wc...ogId=10001&page=Battery-Charging#.UcM8T5ymXFk

Maine Sail has a great website, in addition to his Musings with Maine Sail topics right here on co.com

http://www.pbase.com/mainecruising/installing_a_marine_battery_charger

 

[Benny17441]

It all may depend on your boating style. If you are like many that use the boat in the weekends and then leave it unattended for the 5 work weekdays that charger might work for you as it will have plenty of time to fully recharge the batteries with no other loads present. On the other hand if you also like to take her out midweek or like to spend some time on her at nights using lights and radio you may want to conduct an electrical survey to determine the adequacy of such a charger. I know someone that runs a 2A charger on his boat but his electrical needs are very small and the boat is used infrequently. Whatever works for you.

 

[rgarrison@gmail.com]

thanks, I'll take a look at this article...appreciate it

 

[rgarrison@gmail.com]

My wife and I spend a lot of time putzing around the boat. We leave it on shore power, motor around the marina then sail. Yesterday, we lost our instruments after 2-3 hrs under sail.

 

[Stu Jackson]

rg, not sure if there was a question in your post. First thing to do, before plugging back into shorepower (or leaving it unplugged for at least an hour or two) would be to check the voltage at the house bank. Then restart the charger and check the voltage.

Could be either: broken charger (leading to undercharge), dead batteries or poor connections.

How big a house bank, what kind of charger and batteries, how old are the batteries...

 

[Benny17441]

I presume you have a dedicated engine starting circuit as I heard no complaint other than the loss of instruments. It likely possible that your house bank is composed of the two remaining batteries connected in parallel and that the two banks are controlled via a battery switch. How the charger is connected will play an important part in determining which batteries are being charged. I will risk it and surmise that the shorepower charger is a single bank unit and that the leads are connected solely to the house bank. Now the health of the batteries is of utmost importance as they will determine the storage capacity they can attain. In a two battery bank one weak or damaged battery can discharge or damage the other. You must also ascertain that the battery charger is working by measuring the output voltage which should be between 13.3V and 14.4V. Finally insure you understand the workings of the battery switch to determine which bank is handling the load and or receiving the charge from either alternator or shorepower charger. There are many different ways to wire batteries and dedicate their use and I have just explored the most common so it may or may not apply to your boat. Just insure battery health, charger operation and connectivity.

 

[rgarrison@gmail.com]

good idea, thx, I am off to the boat this morning...taking my multimeter and will test per ur recommendations. FYI there are 2 batteries relatively new, installed mid 2012