Second battery?

[SimonCh]

So i’m looking to get a mooring next year. i’ve purchased a new bilge pump with an internal float switch.

I think i’d like a second battery. i’m quite nervous about batteries anyway and don’t like floating with the GPS/bluetooth speakers going etc.

So id like to add a leisure battery. i’ve read mixed things about how you can’t have a leisure battery and an engine start battery on the same circuit as one will charge the other. I’ve also read that as long as they’re the same age, same style of battery then it’s fine.

Ideally i’d like a 1/2/both isolator and i’d like both to be charged by the engine, but just leave the leisure battery running with a solar panel whilst it’s moored.

Just looking for advice please!

Si out.

[GuyC]

Something like this:

https://www.bluesea.com/systems/42/2...ctrical_System

[Limecc]

I don't know how others have done it but you could use a high power blocking diode to separate the circuits for discharge. The one pictured is probably overkill.


Below is the best and most authoritative resource I ever found regarding batteries.
Car and Deep Cycle Battery FAQ 2020, Battery Manufacturers and Brand Names List 2020, Battery Information Links List 2020 and Battery Reference Links List 2020

[jeffstevens763@g]

you can get duel cycle batteries Numax does them for sure, if running a bilge pump id go for a deep cycle for the pump similar to what caravaners do OMO

[Last Tango]

Just bought a pair of Numax 75AH from Ebay this afternoon for £110 the pair to replace mine. The previous pair have lasted six years but just had a couple of messages from the tracker giving low battery warnings so.......It's less than the price of a tank of fuel.

I use one as by main working/starting battery and the other sits idle in the background being charged by a high current rectifying diode (about £3 if I recall). If it's needed I have a switch that simply connects them in parallel for starting.

[SimonCh]

Originally Posted by Last Tango

Just bought a pair of Numax 75AH from Ebay this afternoon for £110 the pair to replace mine. The previous pair have lasted six years but just had a couple of messages from the tracker giving low battery warnings so.......It's less than the price of a tank of fuel.

I use one as by main working/starting battery and the other sits idle in the background being charged by a high current rectifying diode (about £3 if I recall). If it's needed I have a switch that simply connects them in parallel for starting.

This sounds like what i'm after - do you have a photo or a schematic of what that setup would look like? cheers

[Last Tango]

Originally Posted by SimonCh

This sounds like what i'm after - do you have a photo or a schematic of what that setup would look like? cheers

PM'd.....

[Chanchan168]

I use dual batteries running through a blue sea isolated switch and acr split charge relay. My auto bilge pumps run off the leisure battery so the starter is kept separate.

Once up and running the split charge relay sends the charge to the battery that needs it most and when it’s charged it moves to the other, always keeping them fully up.

Got a little led light on the dash that tells me when it’s charging. Never missed a beat.

The switch is basically on and combine, so you never have to worry about selecting batt 1 or 2 or both incorrectly as it’s just one click.

The kit was called add a battery and I purchased the 120amp one

[SimonCh]

Originally Posted by Chanchan168

I use dual batteries running through a blue sea isolated switch and acr split charge relay. My auto bilge pumps run off the leisure battery so the starter is kept separate.

Once up and running the split charge relay sends the charge to the battery that needs it most and when it’s charged it moves to the other, always keeping them fully up.

Got a little led light on the dash that tells me when it’s charging. Never missed a beat.

The switch is basically on and combine, so you never have to worry about selecting batt 1 or 2 or both incorrectly as it’s just one click. Attachment 135518

The kit was called add a battery and I purchased the 120amp oneAttachment 135519

looks like a good bit of kit, i shall do some digging! cheers

[Salty Pete]

I bought a RIB with a 30 HP Suzuki. The only equipment running off the battery were the navigation lights.

I have installed an Echo Sounder/GPS and a Marine Radio.

Electrical equipment has what is called a "Duty Cycle," and I attempted to find out the Amp/Hours of the generator and its duty cycle. Without success.

I know people have had problems with loading up their vehicles with batteries for camping etc. and blowing up their generator from overheating. The same has occurred from dirty battery terminals, ie the generator can't charge the battery so it tries to keep charging with the same result.

I decided that for unessential power, I would have a separate battery charged from home power and if it runs out of herbs it won't effect the running of the boat.

[Pikey Dave]

Originally Posted by Salty Pete

I bought a RIB with a 30 HP Suzuki. The only equipment running off the battery were the navigation lights.



I have installed an Echo Sounder/GPS and a Marine Radio.



Electrical equipment has what is called a "Duty Cycle," and I attempted to find out the Amp/Hours of the generator and its duty cycle. Without success.



I know people have had problems with loading up their vehicles with batteries for camping etc. and blowing up their generator from overheating. The same has occurred from dirty battery terminals, ie the generator can't charge the battery so it tries to keep charging with the same result.



I decided that for unessential power, I would have a separate battery charged from home power and if it runs out of herbs it won't effect the running of the boat.

You’re overthinking this. The “duty cycle” of the alternator will be constant. For the (minimal) load that you’re using, the charging system will be well on top.

[Maximus]

[QUOTE=SimonCh;823577]So i’m looking to get a mooring next year. i’ve purchased a new bilge pump with an internal float switch.

I think i’d like a second battery. i’m quite nervous about batteries anyway and don’t like floating with the GPS/bluetooth speakers going etc.

So id like to add a leisure battery. i’ve read mixed things about how you can’t have a leisure battery and an engine start battery on the same circuit as one will charge the other. I’ve also read that as long as they’re the same age, same style of battery then it’s fine.

Ideally i’d like a 1/2/both isolator and i’d like both to be charged by the engine, but just leave the leisure battery running with a solar panel whilst it’s moored.

Just looking for advice please!



Absolutely NO NEED just a good quality adequately spec single will be fine
....and on a smallish RIB the extra weight will be detrimental...I have two bilges and pumps have moored in torential rain many times without any problem.
Save you're money Save weight and stop worrying is my advice

[Salty Pete]

G'Day Pikey

Yes, I am running minimal equipment at the moment but, you may have noticed I want to run some non-essential items, the reason for having an extra battery.

Maximus hi to you too

An extra battery is detrimental to what?

I am a member of the Sea Rescue and every month the statistics for rescues are emailed to me. Electrical faults are high on the list including flat batteries.

Without that information nobody really knows what problems boaters have.
That is why I prefer to keep my standard electrics as basic as possible and use a seperate battery charged independently

[GuyC]

Originally Posted by Salty Pete

G'Day Pikey

Yes, I am running minimal equipment at the moment but, you may have noticed I want to run some non-essential items, the reason for having an extra battery.

Maximus hi to you too

An extra battery is detrimental to what?

I am a member of the Sea Rescue and every month the statistics for rescues are emailed to me. Electrical faults are high on the list including flat batteries.

Without that information nobody really knows what problems boaters have.
That is why I prefer to keep my standard electrics as basic as possible and use a seperate battery charged independently

If the second battery is installed correctly, which is what the various links point to, then it won't impact on any of the 'safety critical' items.

With the relatively small load that 'hotel' services have, I've never come across issues with duty cycles but I don't think running lights, VHF and chartplotter would use more than about 6 Amps so it would be well within a duty cycle of a normal alternator.

I guess in vehicles, people have inverters, fridges, spotlights, air con etc that are big consumers so the problem might be more relevant. I think with boats it tends to be the length of time things are on rather than current draw.

The OP's question related to a bilge pump that would be left on whilst the boat was afloat so it isn't affected by any additional equipment. I don't think it would be practical to have a separate battery that you would manhandle on / off the boat each time particularly as the time you would want it on charge would be when you were on the boat.

A small bilge pump draws about 2 Amps when operating and if it is an auto pump, it only uses about 0.2A per day so I think it would be feasible to have it running from the main battery for quite prolonged periods of time. That approach would reduce the weight by 25kg'ish and free up space for your sandwiches.

That is not the route I've gone down and I've added a hotel battery as it just gives a bit more peace of mind that the boat will start regardless of what I've inadvertently left on.

I have a Rule 25SA that is connected to the battery side of the isolator via a 3A fuse and a switch. If the boat is in the water I leave it on. If it's not in the water I try and remember to turn it off. To simplify it, you could dispense with the switch and just pull the fuse.

[Pikey Dave]

Originally Posted by Salty Pete

....you may have noticed I want to run some non-essential items....

I must have missed that🤷*♂️[emoji848]

[SimonCh]

[QUOTE=Maximus;824372]

Originally Posted by SimonCh

So i’m looking to get a mooring next year. i’ve purchased a new bilge pump with an internal float switch.

I think i’d like a second battery. i’m quite nervous about batteries anyway and don’t like floating with the GPS/bluetooth speakers going etc.

So id like to add a leisure battery. i’ve read mixed things about how you can’t have a leisure battery and an engine start battery on the same circuit as one will charge the other. I’ve also read that as long as they’re the same age, same style of battery then it’s fine.

Ideally i’d like a 1/2/both isolator and i’d like both to be charged by the engine, but just leave the leisure battery running with a solar panel whilst it’s moored.

Just looking for advice please!



Absolutely NO NEED just a good quality adequately spec single will be fine
....and on a smallish RIB the extra weight will be detrimental...I have two bilges and pumps have moored in torential rain many times without any problem.
Save you're money Save weight and stop worrying is my advice

Decision made. I'll buy a new battery at the start of the season, and also a battery booster pack, just in case!