More battery questions.......

[All_at_Sea]

I have two sealed 200 ah domestic and a 100 ah starter battery. The two domestic ones are now 10 years old and starting to give problems. I have a smart charger and an uprated alternator onboard. Boat in Portsmouth, sailing boat.

I am thinking of buying two new similar ones but which manufacturer or doesn't it really matter? These are the big ones with poles at one end, should l go for a larger AH at the same time? (Not actually necessary but an option if l am buying anyway)

 

[dom]

You're really best to start with a full power audit to include both charging capacity and expected usage.

The idea is to have a little over 2x maximum expected usage as domestic bank capacity and some way to ensure that the batteries aren't left drained for too long.

Big banks beyond the charging systems reach to replenish are really only useful for overnight stops away from the marina.

 

[RichardS]

I have two sealed 200 ah domestic and a 100 ah starter battery. The two domestic ones are now 10 years old and starting to give problems. I have a smart charger and an uprated alternator onboard. Boat in Portsmouth, sailing boat.

I am thinking of buying two new similar ones but which manufacturer or doesn't it really matter? These are the big ones with poles at one end, should l go for a larger AH at the same time? (Not actually necessary but an option if l am buying anyway)

They sound like the same 4D-size 200 Ah sealed AGMs that I have with the at the terminals across the narrow end. Mine are in a battery tray which is simply not going to take a physically larger battery. I think you can get up to 210 Ah or so in the same 4D size but it's really a trivial difference.

Richard

 

[Puggy]

Hi

As Dom says, you should use this as an opportunity to look again at your capacity and charging arrangements. Having replaced all of my batteries and chargers, in summary this is what I did:

3x BP Rolls AGM 210AH deep cycle batteries - very expensive and very good quality
2 x Optima red top 75ah spiral batteries for the bow thruster
1 x Optima red top 75ah spiral batteries for the engine starter

I am very happy with all the batteries - the spiral ones are amazing and really pack a punch. With the bow thruster their endurance and ability to recharge quickly is amazing. Not a cheap solution though...

Battery charging - I have an 100AH alternator and smart charger off the main engine (not nearly enough but difficult to fit a larger or second alternator) with a MOSFET charge splitter across all batteries.
1 x 100AH Cristex charger for the domestics (noisy fans run all the time and has so far been unreliable so not really recommended) and ideally I would have a second in parallel to speed up charging when using the genny.
I have a 30AH Cristec charger for the engine and bow thruster batteries - works well, silent and so far reliable.

So work out what you need and make sure you can charge the batteries properly. Space will be a consideration so see what you can install. Go for a single large battery rather than multiple smaller ones if you can as simplifies installation, removes points of failure and the batteries tend to not increase in cost linearly.

Puggy

 

[temptress]

I have two sealed 200 ah domestic and a 100 ah starter battery. The two domestic ones are now 10 years old and starting to give problems. I have a smart charger and an uprated alternator onboard. Boat in Portsmouth, sailing boat.

I am thinking of buying two new similar ones but which manufacturer or doesn't it really matter? These are the big ones with poles at one end, should l go for a larger AH at the same time? (Not actually necessary but an option if l am buying anyway)

Put as big a capacity as you can fit in the sapce then make sure you can charge it properly. I am sitting on board in Malaysia with the fans going in each cabin 8 or 9 hours a day, the fridge is my biggest power user. i have 580ah in the domestics and a 160amp smart alternator on the engine with 200 wats of solar via an mppt controler. it is late afternoon and i am still getting 5.6 amps into the system from tbe solar (between say 10am and 3pm i usualy get 7 or 8amps)

forget these power audit junkies. in 17 years I have never been able to work out my consumption there are simply too many variables . Get the biggest battery bank you can and try not to take it below 40% (ideally 50%). go sailing and worry about other things.

imo just get big batteries. i have tried gel/agm/sealed/wet and anything else going and come to the conclusion batteries are consumable items and it is not worth the money paying for the fancy ones. Good wet cell traction batteries are fine. (although i do have a 110ah agm dedicated to the engine starting)