House Battery Bank Size

[Zil]

There is a balance that has to be met. Yes we have to account for the daily use. But installing a battery bank should always include the means to recharge the bank. Different chemistry requires different charging arraignments.

[mr-canada]

I have a boat similar in size to you (26.7 ft). I use a simple $150 large truck battery (990 cca) with a small $40 1.1amp smart charger (chipped, five phase) thats always connected to the battery and plugged in. It has a memory so when i plug the boat back in it automatically starts testing the battery for its state and picks up at the right phase and voltage.

Because its always plugged in when the boat is at rest it gives the battery an amazing charge (these smart chargers can revive old batteries that no longer hold a charge) and im good with a similar setup to you for three days as long as im not blasting the stereo amd running all the lights all night.

My load is a vhf radio, sounder, small gps, stereo, some 1A interior lights and i have a small inverter for phones/ tablets that can output up to 100w burst or 45w steady.

Ive contemplated a bigger battery as i ran out of juice last year at a dock without shore power, but since ive ditched my old 15A dumb charger and gone with two 1.1A smart chargers (one is on my truck as a battery maintainer as i dont drive it) i dont think ill need it.

Depends how long you figure your going to need to go without access to power. If you plan on long voyages or a lot of time in areas where you cant overnight at a marine without shore power you will want more capacity than my rig. If your gunkholing around doing coastal cruising where there are usually decent marinas nearby you will be fine.

Also, you dont mention the capacity of your alternator which is key. If you have a 6-12 amp alternator you can always run the motor for a while if the juice is getting low, plus there are always going to be times when you are either too lazy to hang the rags or there is no wind and you want to get someplace. A days worth of motoring with a 12A alternator would be enough to take a nearly dead battery to half way if your using a truck battery, enough to get you closer to shore power for a night.

In conclusion id say the litmus test for you would be how long you expect to be away from a dock with shore power. If most of your trips are coastal gunkholing and weekenders just get a smart charger for when the boat is at rest and between that and your alternator you should be fine if the battery is in decent shape.

[Kevin84]

Originally Posted by mr-canada

I have a boat similar in size to you (26.7 ft). I use a simple $150 large truck battery (990 cca) with a small $40 1.1amp smart charger (chipped, five phase) thats always connected to the battery and plugged in. It has a memory so when i plug the boat back in it automatically starts testing the battery for its state and picks up at the right phase and voltage.

Because its always plugged in when the boat is at rest it gives the battery an amazing charge (these smart chargers can revive old batteries that no longer hold a charge) and im good with a similar setup to you for three days as long as im not blasting the stereo amd running all the lights all night.

My load is a vhf radio, sounder, small gps, stereo, some 1A interior lights and i have a small inverter for phones/ tablets that can output up to 100w burst or 45w steady.

Ive contemplated a bigger battery as i ran out of juice last year at a dock without shore power, but since ive ditched my old 15A dumb charger and gone with two 1.1A smart chargers (one is on my truck as a battery maintainer as i dont drive it) i dont think ill need it.

Depends how long you figure your going to need to go without access to power. If you plan on long voyages or a lot of time in areas where you cant overnight at a marine without shore power you will want more capacity than my rig. If your gunkholing around doing coastal cruising where there are usually decent marinas nearby you will be fine.

Also, you dont mention the capacity of your alternator which is key. If you have a 6-12 amp alternator you can always run the motor for a while if the juice is getting low, plus there are always going to be times when you are either too lazy to hang the rags or there is no wind and you want to get someplace. A days worth of motoring with a 12A alternator would be enough to take a nearly dead battery to half way if your using a truck battery, enough to get you closer to shore power for a night.

In conclusion id say the litmus test for you would be how long you expect to be away from a dock with shore power. If most of your trips are coastal gunkholing and weekenders just get a smart charger for when the boat is at rest and between that and your alternator you should be fine if the battery is in decent shape.

Only downside to this is constantly having to be at a marina to recharge. That can get expensive after awhile. If you stay in the same area and maintain a slip there, its great. But if you're planning on doing any sailing outside your normal area, you may want a bit more robust charging system.