Batteries!!!! need new ones. Info please

[PaulRainbow]

please see edited post above for the list of power consumption


Need to know what types of batterys would suit. It would be a house battery and wouldn't be needed for engine start.

what ah/cold crank values would I need to be looking at ?

Cranking amps are irrelevant, you're not cranking, ah is what you need.

You don't provide enough information for an accurate assessment. You need to work out how much power you will require in, say, a 24hr period

Take your nav lights, divide the 25w by 12 to give you amps, 2 amps is close enough. So if you were going to have the nav lights on for 10 hours they'll use 20 ah. Work that out for all of your equipment and add them together, that'll give you your total power requirements for a 24 hour period with no charging. To keep SOC above 50% you need at least double those ah, i'd go for 3 times. If you want enough capacity for more than 24 hours, you'll have to add some more.

If you have any sort of charging going on you can make an allowance for that.

Bare in mind that the fridge should not be running 24/7, it may only run 20-30 mins in the hour.

 

[tonkatoy87uk]

thanks for the reply.

Its on a fishing pleasure boat so the most we are out is 2 tides . 1-2hours before tide and same after. About n hour -2 hours steam on the way out and back in, Plus position changes through the day, so not totally reliant on the entire power availability of the battery if that makes sense

for the electrics that will be used when the engine is on would they just be waiverd in the calculations ?

trying to keep up lol

 

[PaulRainbow]

thanks for the reply.

Its on a fishing pleasure boat so the most we are out is 2 tides . 1-2hours before tide and same after. About n hour -2 hours steam on the way out and back in, Plus position changes through the day, so not totally reliant on the entire power availability of the battery if that makes sense

for the electrics that will be used when the engine is on would they just be waiverd in the calculations ?

trying to keep up lol

Assuming you start with the batteries charged (if not fit a mains charger or some solar panels).........

Using the figures i posted previously, work out how much you'll need for the whole round trip. If your alternator will keep up with consumption (it should do) you can disregard the time spent with the engine running.

50% is the max you want to discharge the batteries, to fit twice as many ah as you think you'll use. Better yet, fit enough so the batteries don't get below 75-80% and they'll last longer.

 

[tonkatoy87uk]

Solar panels. talk to me.

seen loads of ebay they ok or not to bother?

 

[PaulRainbow]

Solar panels. talk to me.

seen loads of ebay they ok or not to bother?

Quality panels last a very long time, i've got a pair from the 80's still working fine. I'd look at Photonic Universe.

 

[RobF]

Quality panels last a very long time, i've got a pair from the 80's still working fine. I'd look at Photonic Universe.

Lensun are also good. I think the general consensus with Solar is buy cheap, buy thrice (or something like that).

Would be interested to know why Mr Rainbox is extolling conventional lead/acid rather than AGM. I've heard AGM is the new panacea for all marine batteries?

 

[PetiteFleur]

I also use Photonic Universe solar panels but fitted a dual battery PWM controller so you can put an out put to either battery/battery bank. I'll be using 20% to the engine battery & 80% to the domestic bank. This can be varied in 10% stages. When one battery is fully charged, all the output goes to the other battery. I have 1 x starter battery & 2 x 90ah domestic batteries in parallel. Currently I have a 50w panel but am increasing to 80w this winter. I also have room for 2 x 20w extra panels if not sufficient in the future. Only fitted 5 weeks ago so still learning to see if it all works!

 

[tonkatoy87uk]

right here goes

going on the above math's

based on a 12hr outing at night everything on without any running of engine . all a very very rough guess

84 Ah

deck lights - 3.33A - 12hrs
cabin lights - 2.5A - 12HRS
Nav lights - 2.08a - 12hrs
Power sockets ( full capacity) 100a - 6hrs
fridge - 2.5A - 6hrs
radar - 2.5a - 12hrs
vhf - @ 25w full power 2.08A - 6hrs (guess)
raymarine a98 - 1.25A - 12hrs
with downvision&chirp - 3w - - 12hrs
diesel heater - 4.17a - 6hrs


ENGINE RUNNING

16ah

Window wipers 2.5a - 4hrs if over spray
window heaters - 50a - 4hrs
Search lights - 25a - 4hrs
front deck lights 4.17a - 2hrs
Windlass - 150- 2hrs

this is probbaly way out but its working on a rough guage of being out at night, cold and needing to chat to everyone on the vhf lol.

feel free to correct my errors.

86 x 3 = 252ah

16x3 = 48 - IF the workings are they same with a running engine?

need to check what size alt we have.

what size solar panels would I need. I'm gonna guess half of the value as the above was at everythings max tbh.

 

[PaulRainbow]

right here goes

going on the above math's

based on a 12hr outing at night everything on without any running of engine . all a very very rough guess

84 Ah

deck lights - 3.33A - 12hrs
cabin lights - 2.5A - 12HRS
Nav lights - 2.08a - 12hrs
Power sockets ( full capacity) 100a - 6hrs
fridge - 2.5A - 6hrs
radar - 2.5a - 12hrs
vhf - @ 25w full power 2.08A - 6hrs (guess)
raymarine a98 - 1.25A - 12hrs
with downvision&chirp - 3w - - 12hrs
diesel heater - 4.17a - 6hrs


ENGINE RUNNING

16ah

Window wipers 2.5a - 4hrs if over spray
window heaters - 50a - 4hrs
Search lights - 25a - 4hrs
front deck lights 4.17a - 2hrs
Windlass - 150- 2hrs

this is probbaly way out but its working on a rough guage of being out at night, cold and needing to chat to everyone on the vhf lol.

feel free to correct my errors.

86 x 3 = 252ah

16x3 = 48 - IF the workings are they same with a running engine?

need to check what size alt we have.

what size solar panels would I need. I'm gonna guess half of the value as the above was at everythings max tbh.

Assuming your figures are correct, i didn't check them, i'd be inclimed to fit 3 110-130ah leisure batteries. Battery megastore do some good deals.

As to what type, given the type of boat/use etc i'd just go with some plain old lead acid batteries.

Solar..... if you're only using the boat at night, not worth fitting unless you want them to keep the batteries topped up on a mooring. If you use it during the day, i's normally say fit whatever you have room/budget for, but no point going overboard if you have a big enough battery bank and you can charge the batteries with the engine and some shore power.

You keep the boat on a mooring or in a marina with shore power ?

 

[PaulRainbow]

Lensun are also good. I think the general consensus with Solar is buy cheap, buy thrice (or something like that).

I've always said that solar is a long term investment and good panels make sense. We are starting to see posts on here where the cheap and nasty panels are failing, for one reason or another, after a very short time.

Would be interested to know why Mr Rainbox is extolling conventional lead/acid rather than AGM. I've heard AGM is the new panacea for all marine batteries?

Until my last post, i don't think i've mentioned battery types. But, depending on various factors, i'd recommend different batteries for different circumstances.

 

[tonkatoy87uk]

Thanks for the replys

We have no shore power so have to live with what we can create within. I have a fair bit of roof space but not sure whats left of the budget after 3 batteries ha. Do I really need 300ah considering some of it will only be used when the engine is on Im thinking about weight now as we already have 2 other start batterys which are not that light either. The majority of the sessions are day trips but again with winter coming up its going to be heaters and lights. Mainly because some clever person at Arvor thought it would be a good idea to make the 25 with non removeable tinted windows. Add leaking seals to that leading to condensated windows. you might aswell put a bag over your head and sail.
the window heaters are an attempt (not yet tried) to keep the condensation down. and the search lights to see where we are gong to get out of our mud mooring and up the creak. dodging islands and scaffold poles. it can be fun and.... ill change me pants moments too ha.

 

[PaulRainbow]

Thanks for the replys

Do I really need 300ah

You did the sums

 

[tonkatoy87uk]

Can anyone rate Shield mf27100 batterys

 

[RobF]

...
Until my last post, i don't think i've mentioned battery types. But, depending on various factors, i'd recommend different batteries for different circumstances.

At the risk of being a bit pedantic, I understood you were recommending Lead Acid in Post #2 (with a link to a Lead Acid battery) and followed this up with a comment in Post #12 which referred to the size and type of battery noted in Post #2

However, would be interested to know when you would recommend AGM. The sealed design and deep discharge abilities of AGM appeal to me, but the additional cost doesn't.