Leisure batteries - relocation

[SkyMover]

All of my boats batteries (1 x Start and 3 x 110AH domestic; all of the ‘sealed’ type) are in the engine compartment - which doesn’t have much room. Their placement isn’t ideal ; they affect the trim of the boat (there is a definite list to port) and they are very difficult to get at (not that l need to get at them very often). Also the wiring has become a bit of a mess and needs a complete rewire to tidy it all up.

What are the possible issues/risks if l were to relocate the leisure batteries to the main cabin under the main bed? The benefits for me: the weight is moved centrally (albeit about 5’ further forward from their current location), they will be easier to access, port/starboard trim should improve and l could add a 4^th leisure battery in the future. I’ve reviewed the BSS schedule and cannot find anything that forbids such an arrangement. l think it will come down to a having a suitable battery box with adequate venting to the outside?

 

Any views on this? Does anyone have a similar arrangement?

 

Additionally the 12v breaker box is far from perfect; both in its position and type: awkward to get at and it’s a 240v domestic box – it works but l’ve never been happy with it where it is; l’d rather have something at eye level, alongside the solar and Smartgauge readouts – so l intend to replace it with a more suitable 12V breaker panel. Whoever did the wiring put a separate breaker in for the fridge (for some reason) although the master switch on the main breaker box still has to be switched on. Seems a bit unnecessary to me - I’m all for keeping things as simple as possible.

Any do/don’t do here?

 

Chris

 

P.S - I’ll add some photos of the current setup later when l can get to the boat.

Edited June 7, 2018 by SkyMover
typos

[Alan de Enfield]

Check the BSS section 3:1:1

 

Identify the location of all batteries.
If batteries are stored within an engine, accommodation or other nondedicated
battery space, check that the space is ventilated.
If batteries are stored within a dedicated battery space or box:
• check if the space or box has any ventilation; and,
• check the height of the ventilation provision and the route of
any ducted ventilation.
Check the ventilation pathway from all battery storage locations
leads to the outside of the hull or superstructure.

 

NOTE ‐ if batteries of a ‘sealed’ type are stored in a non‐ventilated space verify that storage in
unventilated spaces meets with the battery manufacturer’s recommendations by reference to presented
documentation from the manufacturer.
NOTE – ventilation pathways into accommodation spaces having fixed high‐level ventilation or into canopied
areas are acceptable.
NOTE – battery covers must not allow the accumulation of hydrogen gas.

[SkyMover]

Thanks Alan,

 

That's the section l'd read - if the venting is just to prevent possible Hydrogen build up them a suitable route from the lid of the box to an exit point which is higher would be adequate? It wouldn't need to be 'actively' vented? Or maybe just a grille on the lid would be OK?

 

It sounds like it's achievable; l won't be starting this until September (ish). So plenty of time to plan.

 

Chris

 

[MtB]

53 minutes ago, SkyMover said:

What are the possible issues/risks if l were to relocate the leisure batteries to the main cabin under the main bed? The benefits for me: the weight is moved centrally (albeit about 5’ further forward from their current location), they will be easier to access,

 

Really? Batteries under the bed sound a right PITA to access, to me. 

 

Best place for optimum access is in racks on the wall in the engine room in my opinion.

 

If you don't have an engine room, the kitchen worktop is pretty good too. But the wimmins usually have some petty and trivial objections to that, in my experience. Huh.

[mrsmelly]

One other point would be you will need substantial electric string if its several feet away from alternater.

[Alan de Enfield]

28 minutes ago, SkyMover said:

Thanks Alan,

 

That's the section l'd read - if the venting is just to prevent possible Hydrogen build up them a suitable route from the lid of the box to an exit point which is higher would be adequate? It wouldn't need to be 'actively' vented? Or maybe just a grille on the lid would be OK?

 

It sounds like it's achievable; l won't be starting this until September (ish). So plenty of time to plan.

 

Chris

 

I would suggest taking advice from the BSS, it reads a little confusing.

 

1) Vents must lead to outside

2) "Ventilation pathways into accommodation spaces having fixed high‐level ventilation or into canopied
areas are acceptable" Could that be taken to mean that if your 'seat box' vents into the accommodation space, and the accommodation space has 'high level venting' (mushrooms) that no additional venting is needed ?

2 minutes ago, mrsmelly said:

One other point would be you will need substantial electric string if its several feet away from alternator.

Good point - he may need to move the engine to be alongside the new battery location. (insert smiley of choice here)

[peterboat]

My leisure batteries are under the back step in the main cabin where they stay warm and safe!! They are Lifepo4s so dont require venting, they are charged by solar and the whispergen, and arnt attached to the engine [which after the blacking trip in July will be an ex engine]. The electic drive batteries however are in the stern but in insulated boxes to keep warm.

[SkyMover]

17 minutes ago, mrsmelly said:

One other point would be you will need substantial electric string if its several feet away from alternater.

It would be about 5' - so l would think some 16mm2/110A cable would suffice? It would be from the split charge relay rather than the alternator. Alternator is a basic 60A one.

 

[EDIT] - Main charging is solar (400W) for the leisure batteries. I don't use the boat much October - April.

18 minutes ago, Mike the Boilerman said:

 

Really? Batteries under the bed sound a right PITA to access, to me. 

 

Best place for optimum access is in racks on the wall in the engine room in my opinion.

 

If you don't have an engine room, the kitchen worktop is pretty good too. But the wimmins usually have some petty and trivial objections to that, in my experience. Huh.

There is plenty of space under the main bed with easily detachable panels; access would be far, far easier than it is now - l would sacrifice a bit of storage space but worth it. I think....

 

Chris

Edited June 7, 2018 by SkyMover
typo

[Alan de Enfield]

1 minute ago, peterboat said:

The electic drive batteries however are in the stern but in insulated boxes to keep warm.

Do they each have electric blankets like on F1 tyres ?

If so - Doesn't that detract from the available number of electrons that are available to roam around your wiring ?

[peterboat]

2 minutes ago, Alan de Enfield said:

Do they each have electric blankets like on F1 tyres ?

If so - Doesn't that detract from the available number of electrons that are available to roam around your wiring ?

They might do but fortunately the Whispergen creates heat and the wheelhouse is above them as well to keep them warm?

[Tony Brooks]

11 minutes ago, SkyMover said:

It would be about 5' - so l would think some 16mm2/110A cable would suffice? It would be from the split charge relay rather than the alternator. Alternator is a basic 60A one.

 

[EDIT] - Main charging is solar (400W) for the leisure batteries. I don't use the boat much October - April.

There is plenty of space under the main bed with easily detachable panels; access would be far, far easier than it is now - l would sacrifice a bit of storage space but worth it. I think....

 

Chris

 

The BSS specifies a minimum diameter for battery leads and i don't think 16sq mm CCSA is thick enough.

 

The implications from the your second sentence is that the system is wired in a way that invites split charge relay failure. The alternator should supply the domestic bank (and that raises volt drop issues on longer runs) and the relay then sends charge to the engine battery. However you wire it I think you will need larger cable, especially if you wire as your words suggest. This is because the cables will not only have to carry the alternator output but also an undetermined amount of current from the engine battery.

Any inverters or other high current devices in use?

[SkyMover]

Thanls Tony - l was hoping you'd reply to this.

 

As is the split charge relay does supply both start and leisure batteries. The solar via a Tracer 4215BN to the leisure batteiries.  Maybe l worded my reply badly.

Only other high current device is a 1.8kW inverter.

I see what you mean about voltage drop - even with 4AWG/21mm2 cable then the voltage drop would be too much if the alternator is putting out 14.6-14.8v?

 

Worse case is I'll live with the batteries as they are.

 

Chris

 

Edited June 7, 2018 by SkyMover
info

[Dave Payne]

Putting under the bed and venting to the outside would bring cold air in to a place where you dont want cold air to be, cold air meets warm air creates damp bed?

[Tony Brooks]

9 minutes ago, SkyMover said:

Thanls Tony - l was hoping you'd reply to this.

 

As is the split charge relay does supply both start and leisure batteries. The solar via a Tracer 4215BN to the leisure batteiries.  Maybe l worded my reply badly.

Only other high current device is a 1.8kW inverter.

I see what you mean about voltage drop - even with 4AWG/21mm2 cable then the voltage drop would be too much if the alternator is putting out 14.6-14.8v?

 

Worse case is I'll live with the batteries as they are.

 

Chris

 

14.6 to 14.8 volts from an alternator tells me the batteries are moving towards well charged so the current flow will be low, possibly 10 amps or less.

 

Its when the charging voltage is below about 13.5V that the current flow is high and as volt drop on a cable is a function of cable run length, current flow, and the cable CCSA that is when charging volt drop will be high. We can assume that the alternator will be supplying 60 amps to the domestic battery because it is at that voltage its is well discharged BUT well charged (all but fully charged) engine battery will have a higher voltage than the domestic bank so will add some current of its own. I have no idea how much but best assume at least another 20 amps. However if you run the inverter flat out the engine battery will supply even more current up to about 180 amps and that is three times the alternator output.

 

NO - a split charge relay can NOT supply both batteries. The only things that can do that are split charge diodes, four position switches, and fancy electronic gizmos. All a relay, be it split charge or other, can do is connect two circuits items together. In your case the domestic and engine batteries. Once that is done then the charge from whatever source will flow to both banks in proportion to their relative depths of discharge. The problem comes when you connect the alternator to the battery that spends most of its time all but fully charged because if you do that you not only pass the full charging current through the relay but also charge provided by the better charged batteries (as explained above). That tends to overload many split charge relay contacts and eventually burn them out.

 

For simplicity and their own ease marinisers tend to connect the alternator output to the main starter positive terminal that in turn feeds the engine battery and the boat builders rarely change that.  They just wire the split charge relay between the two banks. This is how you imply yours is wired.

 

As we now know you have solar I would suggest that you maximise the effectiveness of your solar when you are away from the boat by changing the split charge relay for a voltage sensitive relay sensed from the domestic bank. Then get some decent able and connect the alternator output to the domestic bank positive. This will allow the solar to charge both battery banks when the domestic bank is well enough charged to allow the charging voltage to reach 13.6 to 13.8 volts (depending upon the relay bought). This is a plus for when you are away from the boat, especially in winter). It will also ensure that the current passing through the relay contacts is normally only the low current demanded by the all but fully charged engine battery.

 

My split charge relay was already wired as I suggest and this autumn I changed it for a VSR. Winter cold starting at monthly intervals was noticeably improved, in fact all cold starting has been.

 

Do not try to oversimplify things to a point of unreliability. There is a good reason why you have a separate breaker for your fridge. The 12V compressor fridges are VERY susceptible to volt drop on start up so need to be wired in exceptionally heavy cable for the running current. Unless the cable from the batteries to master switch and master switch to DC distribution board is huge sharing it with the fridge is likely to end in tears so typically one would wire the fridge from the master switch, via a fuse close to that switch, direct to the fridge with or without a switch at a convenient point but such a switch needs a high current rating. I used a mains 20 amp double pole isolator (maybe 40 amps, can't remember) with the supply passing through both contacts in parallel.

 

Sorry of its all a bit technical.

[Machpoint005]

37 minutes ago, Dave Payne said:

Putting under the bed and venting to the outside would bring cold air in to a place where you don't want cold air to be, cold air meets warm air creates damp bed?

Law of Unintended Consequences again.

There must be some reason why people don't usually put batteries under the bed...

[Tony Brooks]

4 minutes ago, Machpoint005 said:

Law of Unintended Consequences again.

There must be some reason why people don't usually put batteries under the bed...

Yeh, a bit like wanting to connect the fridge to the domestic distribution board.

[cuthound]

Having seen the results of an exploding battery in a dedicated battery room, I certainly wouldnt want to sleep on top of one ?

[MtB]

1 hour ago, Machpoint005 said:

Law of Unintended Consequences again.

There must be some reason why people don't usually put batteries under the bed...

 

 

Another reason not to is you need to be ble to peer down vertically into each cell periodically to check the electrolyte level, and to see the relative amounts of gassing in each cell during charging.

 

Difficult with only one foot of headroom available above batteries fitted under a bed. A mirror and a torch would be one way I suppose....

[Alan de Enfield]

13 minutes ago, Mike the Boilerman said:

 

 

Another reason not to is you need to be ble to peer down vertically into each cell periodically to check the electrolyte level, and to see the relative amounts of gassing in each cell during charging.

 

Difficult with only one foot of headroom available above batteries fitted under a bed. A mirror and a torch would be one way I suppose....

I started to misread that with 'peer' as 'pee' to top up the electrolyte levels …………….

[Detling]

20 minutes ago, Mike the Boilerman said:

 

 

Another reason not to is you need to be ble to peer down vertically into each cell periodically to check the electrolyte level, and to see the relative amounts of gassing in each cell during charging.

 

Difficult with only one foot of headroom available above batteries fitted under a bed. A mirror and a torch would be one way I suppose....

The OP said sealed batteries, they don't have a hole to peer or pee down.

[WotEver]

5 hours ago, SkyMover said:

It would be about 5' - so l would think some 16mm2/110A cable would suffice?

No...

4 hours ago, Tony Brooks said:

The BSS specifies a minimum diameter for battery leads and i don't think 16sq mm CCSA is thick enough.

Yes...

 

From 3.2.2 of the BSS Guide:

The battery cables prescribed in the check must be approximately 25mm2.

[SkyMover]

Thanks for all the replies so far. Learned a few things I didn't know.

 

Very much appreciated.

 

Chris

 

 

[SkyMover]

2 hours ago, Mike the Boilerman said:

 

 

Another reason not to is you need to be ble to peer down vertically into each cell periodically to check the electrolyte level, and to see the relative amounts of gassing in each cell during charging.

 

Difficult with only one foot of headroom available above batteries fitted under a bed. A mirror and a torch would be one way I suppose....

 

Well, there is about 6-7" between the top of the batteries and the rear deck at the moment. A foot would be a big improvement!

 

Chris

 

[Jen-in-Wellies]

3 hours ago, Alan de Enfield said:

I started to misread that with 'peer' as 'pee' to top up the electrolyte levels …………….

Well if it makes the batteries last longer...