I just installed four new house batteries Trojan 6V deep cell 220 amp hr. Do I keep the on board charger - West Marine smart charger - on all the time or charge them let them run down some and then recharge? and not keep the shore power connected all the time.
Charging Batteries - What right ?
- Thread starter Ron D
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With the proper charger...
Ron: With the proper charger you should be able to leave it connected to shore power 24x7. You may want to consider getting some of those special caps if you are not dilligent about checking the fluid level on a regular basis. I know nothing about the WM Smart Charger. We have a Statpower 40+ on our boat and it keeps the batteries in very good shape.
Ron: With the proper charger you should be able to leave it connected to shore power 24x7. You may want to consider getting some of those special caps if you are not dilligent about checking the fluid level on a regular basis. I know nothing about the WM Smart Charger. We have a Statpower 40+ on our boat and it keeps the batteries in very good shape.
for what it's worth
I don't leave the shore power connected.I plug in when I get there and uplug when I (with the obvious exception of when not at dock) leave the boat. If your batteries are properly charged and in good condition they should stay charged for weeks.My reasoning is there is not a galvanic issues if not connected to shore ground.Also as Steve mentioned if you are not diligent about keeping the battery acid level full you risk a battery burning up. Last year there was a battery that exploaded on a boat at our marina for this exact reason of no water in battery,not a pretty picture,as well as needing a new battery there was a major clean up of battery acid and lead.There are lots of people who leave it connected for weeks at a time but if you use your boat every week or two and the boat is water tight there is no good reason I can think of for keeping it on all the time. Electric and water just don't mix well and there is always a risk.Unless there is a overwhelming reason for leaving shore power connected I would advise unpluging it unless you are there at the boat. Your batteries will be fine as todays "smart chargers" will not overcharge your batteries even if your turn the charger off and on several time a day.Talk to a good marine electrican and ask about stray voltage (in the water)and you will never want to swim around your boat when connected to shore power (or even if the boats around you are connected)I always cringe when I walk down a dock and see power cord IN the water. Bottom line here is its your boat your choice.
I don't leave the shore power connected.I plug in when I get there and uplug when I (with the obvious exception of when not at dock) leave the boat. If your batteries are properly charged and in good condition they should stay charged for weeks.My reasoning is there is not a galvanic issues if not connected to shore ground.Also as Steve mentioned if you are not diligent about keeping the battery acid level full you risk a battery burning up. Last year there was a battery that exploaded on a boat at our marina for this exact reason of no water in battery,not a pretty picture,as well as needing a new battery there was a major clean up of battery acid and lead.There are lots of people who leave it connected for weeks at a time but if you use your boat every week or two and the boat is water tight there is no good reason I can think of for keeping it on all the time. Electric and water just don't mix well and there is always a risk.Unless there is a overwhelming reason for leaving shore power connected I would advise unpluging it unless you are there at the boat. Your batteries will be fine as todays "smart chargers" will not overcharge your batteries even if your turn the charger off and on several time a day.Talk to a good marine electrican and ask about stray voltage (in the water)and you will never want to swim around your boat when connected to shore power (or even if the boats around you are connected)I always cringe when I walk down a dock and see power cord IN the water. Bottom line here is its your boat your choice.
What is the IQ of your 'Smart Charger'?
I will offer this situation to you. I have 4 Trojan T-120 like you. I have my original Guest 30A automatic charger. This charger is designed to switch from a 'bulk' mode to a 'float' mode when the batteries are nearly at full charge. (Yes I know that the Guest charger is not highly regarded, but it is a multi-stage device) This works OK for a battery bank that is 100-200 AH in size. However for a bank of 440AH there is a problem. The switching mechanism from bulk to float on this charger depends upon the charging current into the batteries. On this particular charger, the trip point is about 4-4.5 amp. This means that as the batteries become nearly charged and the charging current into the batteries drops to below 4A, the charger switches to the float mode. It stays in the float mode until the charging current becomes greater than 4A due to the battery's discharge. Here is the problem: When flooded lead acid batteries reach full charge, the charging current drops to about 1-2% of the bank capacity at a charge voltage of 14.4V (this is about the bulk charging voltage). For a small bank, that is 2-4 amps. This is low enough for the charger to switch to the float mode. However, for a larger bank like 440 AH 1-2% is 4.4-8.8 amps. At this charging current the 'smart' charger 'thinks' that the batteries are still not fully charged and does not switch to the float mode. Instead it continues to charge the batteries at the bulk voltage and the batteries eventually cook and boil dry. This is a good reason NOT to leave the battery charger connected 24/7. My first set of 6V golf cart batteries fell victim to this situation. Yes, I could have avoided this with more frequent electrolyte checks on the batteries, but I failed to do so. Bottom line- make sure that your charger is the correct size for the bank you are charging. Just because you have a 'smart' charger doesn't mean that is it a genius. I agree that for the conserns of electrolysis that it is definately a BAD idea to stay plugged in all the time.
I will offer this situation to you. I have 4 Trojan T-120 like you. I have my original Guest 30A automatic charger. This charger is designed to switch from a 'bulk' mode to a 'float' mode when the batteries are nearly at full charge. (Yes I know that the Guest charger is not highly regarded, but it is a multi-stage device) This works OK for a battery bank that is 100-200 AH in size. However for a bank of 440AH there is a problem. The switching mechanism from bulk to float on this charger depends upon the charging current into the batteries. On this particular charger, the trip point is about 4-4.5 amp. This means that as the batteries become nearly charged and the charging current into the batteries drops to below 4A, the charger switches to the float mode. It stays in the float mode until the charging current becomes greater than 4A due to the battery's discharge. Here is the problem: When flooded lead acid batteries reach full charge, the charging current drops to about 1-2% of the bank capacity at a charge voltage of 14.4V (this is about the bulk charging voltage). For a small bank, that is 2-4 amps. This is low enough for the charger to switch to the float mode. However, for a larger bank like 440 AH 1-2% is 4.4-8.8 amps. At this charging current the 'smart' charger 'thinks' that the batteries are still not fully charged and does not switch to the float mode. Instead it continues to charge the batteries at the bulk voltage and the batteries eventually cook and boil dry. This is a good reason NOT to leave the battery charger connected 24/7. My first set of 6V golf cart batteries fell victim to this situation. Yes, I could have avoided this with more frequent electrolyte checks on the batteries, but I failed to do so. Bottom line- make sure that your charger is the correct size for the bank you are charging. Just because you have a 'smart' charger doesn't mean that is it a genius. I agree that for the conserns of electrolysis that it is definately a BAD idea to stay plugged in all the time.
Ron, it's your call
The question of staying plugged in to shore power always gets a variety of opinions here at HOW. Here in Puget Sound, in the 35 years I've been hanging around marinas, I've never seen a boat unplugged. And boats here, are in the water year around.
The question of staying plugged in to shore power always gets a variety of opinions here at HOW. Here in Puget Sound, in the 35 years I've been hanging around marinas, I've never seen a boat unplugged. And boats here, are in the water year around.
and how would you keep your beer cool?
Ron: This also brings up the point of how do you keep the beer cold if you are not plugged into shore power? You have got to have your priorities!
Ron: This also brings up the point of how do you keep the beer cold if you are not plugged into shore power? You have got to have your priorities!
charging batteries
Ron: According to MFGRS, wet cell batteries discharge at the rate of 10 percent per week at an ambient temp of 90 degrees F. If you are unplugged, and don't sail for two months, you do the math.
Ron: According to MFGRS, wet cell batteries discharge at the rate of 10 percent per week at an ambient temp of 90 degrees F. If you are unplugged, and don't sail for two months, you do the math.
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