Batteries....what rating?

Hi is 90aH ok or should I go for the 140aH? Curious what other members have?

Depends on what you want the battery to do. 140 is bigger capacity than 90 but if an engine start battery both are probably too big, but if it is your domestic bank then usually the bigger capacity (assuming you have space) is better.
 
As said much depends... Do you have a battery powered fridge or do you run TV or computer for long periods? If yes then probably you will want more capacity. How will it be recharged? Will you be running the engine often or only recharge at marina. (or even take home to charge)
If you ony run LED lights and minimum instruments then small battery will be fine. Big battery will be heavy and expensive compared to smaller battery. You may find it a good idea to see how you get on witha smaller battery with the option of adding another later. More expensive but more flexible in options. good luck olewill
 
The practical consideration is the weight of the battery. I found that the bigest I could lift and move arrounf was the 110Ahr size, so we have 2 x 110AHr batteries in parallel for the house battery which gives us 4 or 5 days capacity or one day with the fridge on to chill.


Good luck
 
There is likely to be a large difference in the physical size of 90 & 140ah batteries and many boats are built to take multiples of 105/110ah batteries.
As others have said it depends what equipment you plan to run. For years we were happy with 110ah of domestic and a separate truck battery for the engine but now we have a fridge, many lights and lots of electronics so have 3 x 110ah & truck battery.
 
[hobby horse]A couple of decent sized solar panels weigh a lot less than a battery and will extend your independence of mains/engine charging significantly, as well as helping your batteries last longer by keeping them topped up[/hobby horse]
 
The practical consideration is the weight of the battery. I found that the bigest I could lift and move arrounf was the 110Ahr size, so we have 2 x 110AHr batteries in parallel for the house battery which gives us 4 or 5 days capacity or one day with the fridge on to chill.

I found the biggest I could lift and move around was 210Ah :). Though admittedly manhandling them down the companionway on my own was a stretch, should have used a tackle really but I was too lazy to rig one up. There was room for two of them in the battery locker, so we have 420Ah in total plus a small (8"x8"x4") engine start battery. Apparently it's usually used for starting snow-mobiles!

Don't really know what our battery endurance is, but it's certainly never been a problem!

Pete
 
[hobby horse]A couple of decent sized solar panels weigh a lot less than a battery and will extend your independence of mains/engine charging significantly, as well as helping your batteries last longer by keeping them topped up[/hobby horse]

You do need to find somewhere to fit them, though, which would be tricky on Ariam without seriously cluttering up the cockpit area.

In practice I've never found the need to urgently plug in, or run the engine just for charging. With AGMs that can accept fast charging, a decent-sized alternator and a smart controller, we get all the charging we need from normal engine use - and I don't think I motor excessively when I could be sailing :)

Pete
 
510 domestic, and another 170 for the engine. Obviously the start battery doesn't need to be nearly as big, but it means they are all identical. Also have wind generator. The original question is impossible to answer without more information re requirements.
 
What size battery you need depends on your usage which only you can estimate. Don't forget that a 110ahr rated battery will only give you approx half of that as you can't charge it above 90% and shouldn't let it drop below 50%. For engine starting, you only need something like a 55ahr provided the cranking current is enough - my engine is only 300cc or so and most yacht engines are less than 1000cc. You don't need a tank battery to turn it over.
 
Just to emphasise the importance that it depends on your needs I get away with about 10AH from a wet NiCad that must be 30 years old. That runs VHF and lights for night sailing. enough for me but probably not for others. olewill
 
I found the biggest I could lift and move around was 210Ah :). Though admittedly manhandling them down the companionway on my own was a stretch, should have used a tackle really but I was too lazy to rig one up. There was room for two of them in the battery locker, so we have 420Ah in total plus a small (8"x8"x4") engine start battery. Apparently it's usually used for starting snow-mobiles!

Don't really know what our battery endurance is, but it's certainly never been a problem!

Pete

When I re-batteried Bigwow, about 8 yrs ago this was my thinking, so I fitted 2X210Ah. Now comes the time to replace them, I am amazed at how they have gained weight and I will need someone to lift them out for me!:encouragement:
 
Curious what other members have?

550AH house bank and 110AH starter, topped up mostly by two 130W solar panels. However this was set up for a family of 4 liveaboard incl a fridge freezer, so overkill for normal sailing.

General rule of thumb is big domestic and smaller starter battery depending on need, but like others I'd strongly recommend getting a solar panel and charger to keep them topped up. Not expensive these days and will make a single 90AH seem like a much bigger battery even in the UK climate.

Another useful thing is a battery changeover switch which allows you to temporarily parallel up the house battery with the starter, so if your starter battery is flat you can use the house bank to get you going. This was standard on our boat and has proven useful on a couple of occasions.
 
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