How many hours on batteries ?

SpottyDog5

SpottyDog5

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I have 2 x 165ah domestic batteries, managed to run them flat over 3 days without shore power or running the engines.
I was running 2 x fridges, lighting and 2 x water pumps for the loos.
Would this be considered "normal" or would you expect them to last longer ?
Even after 2 hours of engine running, whilst returning to our berth, they were taking 50 amps of charge from the battery charger, however they dropped down to slightly less than 30 amps after about an 1 1/2 hrs.
Any thoughts welcome.
Cheers.
 
Sounds about right although you really shouldnt flatten them completele as this vastly reduces their useable capacity when they are recharged. As a rough guide you shouldnt really allow them to drop below about 50% SOC or about 12.1 volts. This would give you a useable 165ah not a lot when you consider you are running two fridges!!

We have 2 105ah batteries but only have one fridge, the lighting is all LED (it is surprising how much power lighting will use) and the usual water pump etc. We can manage three days without running the engine but after that it is time to start giving them some charge again.

Sounds like your batteries were well flat if they were trying to be charged at 50 amps!!
 
As has been already said sounds perfectly feasible with no charge over 3 days.

I think the F43 is a 12-Volt system?

- Depending upon sizes of fridges, ambient temps etc ---- 2-6 A per fridge ?
- "Lighting" ... 8A for each 100watts

soon adds up.
 
Thank you for the replies, its not often, I'm away from shore power for very long, and I was was wondering if the shore power was "masking" poor batteries.
I've just had a call from the Marina, they are are now charging a just a couple of amps, felling much more relaxed now...
I will be sure to check the fluid levels, when I'm over next.
 
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SPOTTYDOG3 said:
I have 2 x 165ah domestic batteries, managed to run them flat over 3 days without shore power or running the engines.
I was running 2 x fridges, lighting and 2 x water pumps for the loos.
Would this be considered "normal" or would you expect them to last longer ?
Even after 2 hours of engine running, whilst returning to our berth, they were taking 50 amps of charge from the battery charger, however they dropped down to slightly less than 30 amps after about an 1 1/2 hrs.
Any thoughts welcome.
Cheers.
Click to expand...

I have 4 250AH batteries (24V so 500AH Capacity) - and two compressor fridges - I would not expect to get more than 3 days use without discharging the batteries more than I would like.
You need to use the rating plate on the fridges to work out how much they will consume so you can work out if your batteries are big enough to cope - and as already mentioned, you need to halve your 'quoted' capacity as you should not go below 50% discharge.
 
There are ways of reducing your power consumption. LED replacement bulbs are a big one. On a larger boat there are a lot of halogen bulbs, changing them greatly reduces your power consumption. Turning the fridges down overnight will also help (although we dont tend to bother as we only have the 1 fridge).

How old are your batteries? It could be they are getting on a bit and have lost a lot of their capacity as well, which would further compound your problem.
 
On reflection, I should have given this more thought, I have 10 lights in the saloon, 6 in the galley area, 4 in the front cabin, 6 in the aft, none are LED.
I have a generator, but didn't use it as we were sharing the pontoon.
 
SPOTTYDOG3 said:
On reflection, I should have given this more thought, I have 10 lights in the saloon, 6 in the galley area, 4 in the front cabin, 6 in the aft, none are LED.
I have a generator, but didn't use it as we were sharing the pontoon.
Click to expand...

Thats getting on for 20A of power just for lighting!! (assuming you had them all on at once of course)
 
you could think about one of these ?

Provides hot water , charges boat batteries , phones,laptops etc all through the mains.
hour in the morning hour at night :)
 
I think you were luckily to survive 3 days frankly. Esp. in some heat.


FWIW - my domestics used to always charge on 50a when charger switched on after say 1/2 day on domestics - with similar use to you. Once voltage restored a bit the charger output would drop to 30a and continue its slope downwards until just trickle.

On occassions when they had some mega drain overnight occassionally my previous 'shot' batteries would not accept any charge from the charger until 1/2hr had passed and then the charger would kick in and slow mount up to 50a over the ensuing 1 hr.
 
BGW said:
I have 4 250AH batteries (24V so 500AH Capacity) - and two compressor fridges - I would not expect to get more than 3 days use without discharging the batteries more than I would like.
You need to use the rating plate on the fridges to work out how much they will consume so you can work out if your batteries are big enough to cope - and as already mentioned, you need to halve your 'quoted' capacity as you should not go below 50% discharge.
Click to expand...

Something I don't quite understand... We are also 24 volts and have 4 x 110AH batteries. Wired up the 'normal' way I understand that we still have 110AH available. Wired them up in both series and parallel which is supposed to give us 220AH. I have no idea how this affects safe usage time. Perhaps someone could explain. :confused:
 
stuhaynes said:
Something I don't quite understand... We are also 24 volts and have 4 x 110AH batteries. Wired up the 'normal' way I understand that we still have 110AH available. Wired them up in both series and parallel which is supposed to give us 220AH. I have no idea how this affects safe usage time. Perhaps someone could explain. :confused:
Click to expand...

When wiring batteries together in series you get the same capacity, but double the voltage - when wired in parallel you get the same voltage but double the capacity.

When wiring 4 batteries for 24V you do both. Firstly you wire two banks of two batteries in series to create two 'large 24V batteries' (in my case 2 X 24V @ 250AH) then you wire those two together in parallel to create the same 24V but with 500AH capacity.

You should have 24V 220AH capacity (and as always, you halve that to the safe working capacity, 110AH @ 24V) - Of course 24V has half the current draw of 12V so you have the same capacity as 220AH @ 12V
 
On of the problems with capacity on batteries are that it is impossible to get near to the total capacity of he battery, and even deep cycle batteries are not meant to be discharged to more than half their theoretical capacity. Having two fridges running plus lights etc and water pumps, seems that you did quite well. I have got an 80 watt solar panel which puts quite lot back into the house batteries when there is no other input, such that it normally keep the fridge running over a 24 hour period without any discharge of the house batteries
 
Thanks for all the replies, I have come to the conclusion, my batteries are probably OK, just a bit of lack of thought on my part regarding consumption.
Cheers again.
 
CX54WEK said:
There are ways of reducing your power consumption. LED replacement bulbs are a big one. On a larger boat there are a lot of halogen bulbs, changing them greatly reduces your power consumption. .
Click to expand...

Can you change halogen bulbs for LED ones in the same fitting or do you have to change the fitting as well?
 
SPOTTYDOG3 said:
On reflection, I should have given this more thought, I have 10 lights in the saloon, 6 in the galley area, 4 in the front cabin, 6 in the aft, none are LED.
I have a generator, but didn't use it as we were sharing the pontoon.
Click to expand...

It is surprising how many amps lighting uses. Try looking at your ammeter and then get somebody to switch on the lights and you'll see what I mean. We regularly spend nights at anchor and I'm paranoid about getting my crew to switch off lights. It's also surprising how much juice the anchor light alone uses too. If you've managed 3 days without any problem, you've done well
 
Deleted User said:
Can you change halogen bulbs for LED ones in the same fitting or do you have to change the fitting as well?
Click to expand...

Yes, there is a very good choice here .

Go for warm white and the biggest wattage you can get for your fitting.
If you are unsure give the guy a ring he is very helpful and knowledgeable.
 
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