Boo2
Well-Known Member
I'm interested to know what decides which bank is in use at any one time ? Does the charger alternate between banks in a ping-pmg fashion or is something more complicated involving charge state used ?
Boo2
Why do I need a starter battery?
- Thread starter demonboy
- Start date
I'm interested to know what decides which bank is in use at any one time ? Does the charger alternate between banks in a ping-pmg fashion or is something more complicated involving charge state used ?
Boo2
Bosun Higgs
N/A
The argument for having a seperate battery for starting is the risk of flattening your batteries through domestic demand and then not being able to start your engine. There is no other reason for having a starter battery.
mikegunn
Well-Known Member
Per
I'm away from boat for a couple of weeks and have no details of part No on me, but will be very pleased to supply info as soon as I get back.
Mike
onenyala
Well-Known Member
Jump start battery
I have just bought a 1.5 watt solar panel (£9.99 at Maplins)which I intend to leave connected to the jump start battery so that it will keep it topped up when it is lying festering at the bottom of the fog locker.
I have just bought a 1.5 watt solar panel (£9.99 at Maplins)which I intend to leave connected to the jump start battery so that it will keep it topped up when it is lying festering at the bottom of the fog locker.
halcyon
Well-Known Member
The reson for a seperate engine battery was to avoid volt drop and power spikes affecting navigation equipment. This goes back to the late 70's early 80's when there was a big grouth in electronics fitted to boats, and system resets due to engine starting. Seperate power supply was a side feature, not the maine one.
The low battery problem was covered by the introduction of power lock-out in the same period. This isolated equipment to limit battery drain, providing a power reserve for starting, and improving battery life.
Brian
sailinglegend420
Well-Known Member
Red Flash or Odyysey are AGMs so check out the delivery costs from UK to India. Because they are AGMs they are not hazardous cargo so can be sent cheaply. They can also be mounted anywhere even upside down without the need for outside ventilation.
Our Red Flash is ONLY charged by a 5 watt solar panel, so no VSRs or split charging systems are needed. Even when on shore power it is not charged. Survived 7 years of permanent liveaboard use.
Our Red Flash is ONLY charged by a 5 watt solar panel, so no VSRs or split charging systems are needed. Even when on shore power it is not charged. Survived 7 years of permanent liveaboard use.
Avocet
Well-Known Member
I'd heard that the plate construction of a starter and a leisure battery are different. The leisure battery having thinner plates that are better for being deeply discharged without sulphating up so much, while the cranking battery has thicker plates. Apparently there's a danger of buckling the plates on the leisure battery if too big a current is suddenly asked of it for too long.
I've never seen it written anywhere though - is it a myth?
I've never seen it written anywhere though - is it a myth?
William_H
Well-Known Member
Batteries
If you are obsessive about your domestic battery supply of not discharging beyond 50% then no you don't need an engine battery. Any large deep cycle battery bank will easily supply engine start current. Just add another house battery in parallel which will get more charging current and reduce the % of discharge between charges.
However note you are now without a standby if and when you do discharge the house battery or it dies of old age. The ideal of course is a crank handle but not often supplied or usable.
I would not waste my money on one of those jump start batteries in a pack. Too small and they still die of old age after a few years whether you use it or not. olewill
If you are obsessive about your domestic battery supply of not discharging beyond 50% then no you don't need an engine battery. Any large deep cycle battery bank will easily supply engine start current. Just add another house battery in parallel which will get more charging current and reduce the % of discharge between charges.
However note you are now without a standby if and when you do discharge the house battery or it dies of old age. The ideal of course is a crank handle but not often supplied or usable.
I would not waste my money on one of those jump start batteries in a pack. Too small and they still die of old age after a few years whether you use it or not. olewill
whipper_snapper
Well-Known Member
I have a confession. I have 4 x 100AH batteries connected as a single bank. They are used to start the engine and run all the domestics. It is simple and it works. We also have lots of solar and wind charging - 95% of the charging comes from these so we can be a bit more relaxed about a flat battery, but it has never happened.
I may be a bad person, but I am very comfortable with the simplicity of the arrangement.
I may be a bad person, but I am very comfortable with the simplicity of the arrangement.
vyv_cox
Well-Known Member
It's the other way around, starter batteries have a large number of thin plates designed for maximum surface area, and therefore maximum current output, but which can easily be damaged by deep discharge. leisure batteries These batteries have thicker plates that can deliver less peak current, but can withstand frequent discharging. Quoted from Wiki so it must be true
See here. I have read that carrying out a drop test on a leisure battery is inadvisable due to the effect it may have on the plates.However, yacht auxiliary engine starter motors don't take a massive current, compared with big automotive engines in very low temperatures, so requirements of CCA are more relaxed. There are several good make leisure/starter combined batteries now on the market, I have them on both my boats. The ones in Greece are Bosch, not sure who made the Milford Haven ones but they are supposedly good performers.
BabaYaga
Well-Known Member
CTEK dc/dc-charger
The Ctek charger talked about must surely be the D250S Dual:
http://www.ctek.nu/gb/en/chargers/D250S DUAL
May or should be used together with the Smartpass, which as I understand it is a couple of VSR's in a box:
http://www.ctek.nu/gb/en/chargers/SMARTPASS
It seems to me that this combo basically does what Sterling's A to B charger does, although perhaps not in exactly the same way.
I have no personal experience with neither, but the concept looks clever.
The Ctek charger talked about must surely be the D250S Dual:
http://www.ctek.nu/gb/en/chargers/D250S DUAL
May or should be used together with the Smartpass, which as I understand it is a couple of VSR's in a box:
http://www.ctek.nu/gb/en/chargers/SMARTPASS
It seems to me that this combo basically does what Sterling's A to B charger does, although perhaps not in exactly the same way.
I have no personal experience with neither, but the concept looks clever.
halcyon
Well-Known Member
They can be quite high, a small diesel can pull 500 amp, they just fit a smaller starter motor, so it still pulls high current. It all depends on engine starter motor fitted, on engine temp, state of battery, voltage at starter, etc, but 250 amp is a working load, and is for 30 seconds use in a hour period
Brian
nimbusgb
Well-Known Member
If you are running 4 or 5 deep discharge batteries in parallel then the starter current ( < 250 amps? ) is being drawn equally ( roughly ) from each of the batteries. 50 to 100 amps off any one leisure battery for less than 30 seconds is extremely unlikely to break it.
Demonboy has access to one style of battery, probably a car type high current unit. Putting more in parallel is better for the batteries in the long run in any event because the percentage discharge to get x number of a/hrs out is lower.
Cranking a starter for 30 seconds, even at 250 amps ( unlikley ) only takes about 2.5 amp hours capacity from the battery bank.
Demonboy has access to one style of battery, probably a car type high current unit. Putting more in parallel is better for the batteries in the long run in any event because the percentage discharge to get x number of a/hrs out is lower.
Cranking a starter for 30 seconds, even at 250 amps ( unlikley ) only takes about 2.5 amp hours capacity from the battery bank.
vyv_cox
Well-Known Member
I'm not sure what you mean by a small diesel. The CCA of the 1, 2 and 3 cylinder Yanmars is 200 A and I don't suppose Volvos are a great deal different. That's at -18C. I'm sure the 2.3 litre diesel in my camper van will take a lot more at freezing temperatures, hence my statement.
lw395
Well-Known Member
The point about instruments dropping out on start-up is valid.
My boat used to kill the GPS every time the engine was started, which would normally be about when the pilotage got interesting.
But that can be dealt with very cheaply and more robustly with a small sealed battery backing up the GPS etc.
A single bank of batteries only needs one failure or error to go flat, whether it's leaving a light on for a week or a charger failing. It does happen, even to sensible people.
A dedicated engine battery can have simpler, lower resistance wiring, so it could start the engine more easily, with less wear on the starter. Nothing ruins starters more than starting engines with too little voltage or too much resistance.
But there are good installations with twin house banks, likewise there are poor systems with an independent engine battery. Often the quality of the installation is as important as the right basic configuration.
My boat used to kill the GPS every time the engine was started, which would normally be about when the pilotage got interesting.
But that can be dealt with very cheaply and more robustly with a small sealed battery backing up the GPS etc.
A single bank of batteries only needs one failure or error to go flat, whether it's leaving a light on for a week or a charger failing. It does happen, even to sensible people.
A dedicated engine battery can have simpler, lower resistance wiring, so it could start the engine more easily, with less wear on the starter. Nothing ruins starters more than starting engines with too little voltage or too much resistance.
But there are good installations with twin house banks, likewise there are poor systems with an independent engine battery. Often the quality of the installation is as important as the right basic configuration.
demonboy
Well-Known Member
Thank you all for your responses, they have made very interesting reading. In the time I posted the OP and now I've just read half of The Marine Electrical and Electronics Bible by John C Payne. That, along with this post and my other one about installing the Sterling unit, have been a real education.
FYI - this morning I had on board the 'alternator man', a local who came with my friend, the interpreter. He's only ever dealt with fishing boats so he was fascinated by our boat and its current set-up. His instinct is to mount two alternators, but then I reminded him I don't run a chest freezer to put my fishing catch in! Anyways, I've given him a list of different battery types for him to investigate, though I struggled to explain what AGM stood for! We'll probably end up going for the sealed once more but let's see what he comes back with.
Thanks all, once again.
FYI - this morning I had on board the 'alternator man', a local who came with my friend, the interpreter. He's only ever dealt with fishing boats so he was fascinated by our boat and its current set-up. His instinct is to mount two alternators, but then I reminded him I don't run a chest freezer to put my fishing catch in! Anyways, I've given him a list of different battery types for him to investigate, though I struggled to explain what AGM stood for! We'll probably end up going for the sealed once more but let's see what he comes back with.
Thanks all, once again.
nimbusgb
Well-Known Member
Revive an old thread for future reference ---
If your vessel is MCA coded ( blue ) then
7.5.2 When the sole means of starting is by battery, the battery should be in duplicate and connected to the starter motor via a “change over switch” so that either battery can be used for starting the engine. Charging facilities for the batteries should be available.
If your vessel is MCA coded ( blue ) then
7.5.2 When the sole means of starting is by battery, the battery should be in duplicate and connected to the starter motor via a “change over switch” so that either battery can be used for starting the engine. Charging facilities for the batteries should be available.