What battery type for small offshore cruiser?

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thomd

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Some advice needed please.

I am currently overhauling my boats electrical setup in preparation for sailing offshore potentially Atlantic crossing next year. My boat currently has a basic electrical setup.

My local marine electrician has suggested I do the following

* Install Sterling Alternator booster to my 50A original Hitachi Alternator plus 70A split diode
* Install NASA BM-1 Battery Monitor
* Install 230V Shore supply system with 8A Sterling waterproof battery charger
* Replace my 110AH sealed Starter battery and 110AH sealed leisure battery with a dedicated 'wet' car starter battery and a leisure bank of 2 x 'wet' batteries

Reasons given to me for using wet batteries is that they can be charged more quickly at higher voltage than sealed or AGM batteries so the engine needs to be on for less time etc. I have concerns though about possible spillage threat, slight inconvenience of moving the batteries about in the locker to access the caps and keep them topped up regularly and also for the size of starter battery as I don't have a great deal of space in my battery box.

I would be grateful if anyone has any comments/suggestions/alternatives on the above and whether I should go for wet batteries over sealed or AGM batteries? My boat is only 28 feet with electric windlass but I don't have a refrigerator installed and LED's throughout so minimal usage. I will be installing Wind Gen and solar panels in near future so my intention is not to be too reliant on charging batteries from the engine.

Thanks in advance.
 
Slightly confused thinking here. You need to work out what your potential consumption is before deciding on the storage capacity and charging regime. For example, your needs will be very different if you want to run a fridge and an electric autopilot than if you have no fridge and a wind vane. The windlass, for example is a bit of a red herring as you only use that when anchoring with the engine running so does not require additional capacity or necessarily higher charging capacity. Not sure of the benefits of shorepower unless you intend spending time in a marina, in which case a small charger for the size of battery bank you are considering is a waste of time - you need a proper multistage marine charger.

If you are short of space, an AGM start battery is a good idea as you only need a small capacity, and therefore small physical size, with a VSR to split the alternator charge between that and your service bank. There are arguments for and against wet and AGM for your service bank. Again AGMs are physically smaller for a given capacity, but the choice is more likely to determined by how much capacity you want and the depth of your pockets. However, if you have modest capacity such as you indicate then there is arguably little need to increase your alternator charging capacity, but rely on your solar and wind capacity when sailing.
 
Tranona said:
Slightly confused thinking here. You need to work out what your potential consumption is before deciding on the storage capacity and charging regime. For example, your needs will be very different if you want to run a fridge and an electric autopilot than if you have no fridge and a wind vane. The windlass, for example is a bit of a red herring as you only use that when anchoring with the engine running so does not require additional capacity or necessarily higher charging capacity. Not sure of the benefits of shorepower unless you intend spending time in a marina, in which case a small charger for the size of battery bank you are considering is a waste of time - you need a proper multistage marine charger.

If you are short of space, an AGM start battery is a good idea as you only need a small capacity, and therefore small physical size, with a VSR to split the alternator charge between that and your service bank. There are arguments for and against wet and AGM for your service bank. Again AGMs are physically smaller for a given capacity, but the choice is more likely to determined by how much capacity you want and the depth of your pockets. However, if you have modest capacity such as you indicate then there is arguably little need to increase your alternator charging capacity, but rely on your solar and wind capacity when sailing.
Click to expand...

Thanks for comments. I have worked out some consumptions recently and will be going with approx 220AH storage capacity. I like the idea of an AGM start battery to save space but have been advised that it is not a good idea to use different types of battery for start and leisure bank? This is because the chargers and alternator booster can only be setup for one battery type. i.e if they are set up for wet batteries they would produce too high a voltage and damage an AGM and if set up for AGM charging would not charge a wet battery efficiently? Hence why I need to either go the wet or sealed/AGM route. I am still unsure what to go for.

Am I right in thinking that a VSR is an alternative to a split diode?
 
I've used wet open lead acid for 20 years and not had a spill, even in some very rough seas. You don't say how much solar you will be installing but to give you an idea, our 200W + Aerogen 4 keeps up with fridge 24/7 plus netbook, TV, LED lights etc. in sunnier places than the UK. We have 480AH domestic banks but could happily reduce that by 60% if no fridge, even more if no TV or computer use.

As Tranona says, the windlass can be ruled out due to the engine running when in use. The suggested battery charger size is a joke as 20 amp 3 or 4 stage would be the minimum I would install, only needs one output and much cheaper at caravan shops than chandlers. I treat the engine battery just like my car, needs no fancy charging regime and I just use a 1, 2 , both switch so I can charge or start from either bank. Alternator booster may be a good idea as not too expensive but repeatedly running the engine just to charge batteries isn't a good idea.
 
Rather than the alternator booster, consider a sterling alternator to battery charger. It puts an unboosted charge to the engine start and a boosted to the domestic. Optima also make very nice and physically small batteries - someone on here has them and rates them

Agree re the shore power. If you're crossing the Atlantic you will need quite a cable to run that!! I would instead spend the money on solar/ wind - possibly a wind/ towed generator. With enough capacity, that will also cover you in this country.

If you are keen on shore-power then don't bother with a tiny 8a charger. You need to be easily able to put back overnight the discharge. I would be looking for 3-4 times that capacity and via a smart charger that will drop to float charge as you get past 80% state of charge - that last 10-20% will take hours as the batteries become closer to capacity.
 
thomd said:
Thanks for comments. I have worked out some consumptions recently and will be going with approx 220AH storage capacity. I like the idea of an AGM start battery to save space but have been advised that it is not a good idea to use different types of battery for start and leisure bank? This is because the chargers and alternator booster can only be setup for one battery type. i.e if they are set up for wet batteries they would produce too high a voltage and damage an AGM and if set up for AGM charging would not charge a wet battery efficiently? Hence why I need to either go the wet or sealed/AGM route. I am still unsure what to go for.

Am I right in thinking that a VSR is an alternative to a split diode?
Click to expand...
Yes, a VSR automatically splits the charge but without the voltage drop you get with a diode. With your 220AH capacity the normal alternator will be sufficient to recharge effectively. If you have solar and wind and are not using high consumption equipment like fridges and radar then difficult to see how you will run down your capacity such that rapid charge is needed. No problem in having an AGM start battery and either wet or AGM for services. in reality you use very little from the start battery and it is fully recharged within minutes after a start and all the charge goes into the service bank. Suggest you have isolators for each bank and a means of paralleling to use the service bank for start in an emergency. Have a look at the BEP Marine switch cluster which does that and has a VSR built in. agree with the others about having a minimum 20A multistage mains charger. These usually have at least 2 outputs which can be set to charge any type of battery.
 
Much depends on just how much money you want to spend and how sophisticated you want the system to be. Yes a simple VSR for charging service battery from engine alternator and engine battery. The battery types are not so critical if you only charge them at 14 volts from existing alternator regulator.
From there next step in sophistication might be an alternator to battery charger for charging service batteries would be a better idea.
Here the charger box takes the voltage from the alternator and engine battery at about 13volts (hopefully correct voltage to charge engine battery) then converts it up to a voltage like 15volts to fast charge the service battery. (in stages for fast charge). This has some ineficiencies but will take the voltage from the alternator as it comes. ie at high current draw the alternator voltage might fall but that is OK. It could however run your alternator near max rating so shorten life.
battery monitors etc can be useful but are a real luxury. An amp meter or meters to different functions but especially charge current would be desirable so you know when further engine running for battery charging is not worth the fuel and noise. good luck olewill
 
Tricky :)

If there is a "standard" cruisers battery then it would be the trojan t105 6v 225Ah. But they're quite big and heavy, might not fit. A downside of AGM or sealed is you only need to get the charging wrong once and you've trashed the battery, also maintenance is important, it's very hard to get the batteries back up to full charge everyday so equalising is needed for a long life. But no real answer, your call.
Wing gens are good now and again but in the tropics tend not to do a great deal, Downwind sailing and anchorages can be tucked in behind hills away from the trades, so you are more reliant on solar and cycling the batts every night, though fridge less you might not use much unless you use a laptop. 10.1" tablets are great :)

What instruments are you running? With a good led masthead and ais standalone reciever you can see lots and be seen down to a low voltage.

Also a cheap class t amp uses much less power than a normal can radio with good sound quality so you can have music/podcasts as much as you want.
http://www.ebay.co.uk/sch/i.html? _odkw=class+d+amplifier+12v&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.Xclass+t+amplifier+12v&_nkw=class+t+amplifier+12v&_sacat=0

Happy hunting :)
 
jac said:
Rather than the alternator booster, consider a sterling alternator to battery charger. It puts an unboosted charge to the engine start and a boosted to the domestic. Optima also make very nice and physically small batteries - someone on here has them and rates them

Agree re the shore power. If you're crossing the Atlantic you will need quite a cable to run that!! I would instead spend the money on solar/ wind - possibly a wind/ towed generator. With enough capacity, that will also cover you in this country.

If you are keen on shore-power then don't bother with a tiny 8a charger. You need to be easily able to put back overnight the discharge. I would be looking for 3-4 times that capacity and via a smart charger that will drop to float charge as you get past 80% state of charge - that last 10-20% will take hours as the batteries become closer to capacity.
Click to expand...

Agree on larger AC charger will go for at least 20A.

For the DC charging if I have understood correctly I could install an 80A Sterling Alternator to Battery Charger which would send an unboosted voltage to the Start battery which would be safe for an AGM battery such as a Redflash or Optima. But it will also send a boosted voltage to the house bank and provide multi stage charging so wet batteries could be used. The built in split diode keeps the start battery and house bank separate meaning different battery types can be used safely i.e AGM start and wet house bank? No need for a VSR with this setup.

Have I got this right?
 
Possibly but why not go for the solar earlier in place of the alternator to battery charger? We have 125w of solar which means the 40ah digital mains charger doesn't get used much now and held back on a A2B as the benefits are less clear as the solar keeps the batteries charged up.

Pete
 
I think it depends really on how you use your boat and the load. Only mentioned the A to B as OP was suggesting alternator booster which usually involves opening up the alternator and was also going with VSR but had concerns re different battery types. All of which IMO the a to b could deal with.

Of course if you are going to using engine very little then anything engine driven is pointless and agree that solar / wind is the way to go
 
Thanks for all the comments. I have decided to go with.

* Sterling Alternator to battery charger
* Sterling 20A Pro Charge for shore power charging
* Odyssey AGM PC925a start battery
* I will likely replace my sealed leisure batteries with 2 x 6V Trojan T-105's in due course and wire in series to get 12V.

I am having difficulty deciding where to mount the chargers as my boat is only 28 feet and space is tight. My local marine electrician suggested mounting the Pro Charge and breakers in the cockpit locker and the Sterling A2B in the battery compartment.

I have concerns over both. The cockpit locker is damp and ventilation isn't great and the manual for the A2B says don't mount in battery compartment due to risk from spark from charger and vented gases from the batteries!

As an alternative I am debating whether to mount the Procharge and breakers high up in the hanging/wet locker in the cabin as this has much better ventilation than the cockpit locker. Have any others mounted a charger in the battery locker or is this a big no no? Any thoughts would be appreciated.
 
thomd said:
Thanks for all the comments. I have decided to go with.

* Sterling Alternator to battery charger
* Sterling 20A Pro Charge for shore power charging
* Odyssey AGM PC925a start battery
* I will likely replace my sealed leisure batteries with 2 x 6V Trojan T-105's in due course and wire in series to get 12V.

I am having difficulty deciding where to mount the chargers as my boat is only 28 feet and space is tight. My local marine electrician suggested mounting the Pro Charge and breakers in the cockpit locker and the Sterling A2B in the battery compartment.

I have concerns over both. The cockpit locker is damp and ventilation isn't great and the manual for the A2B says don't mount in battery compartment due to risk from spark from charger and vented gases from the batteries!

As an alternative I am debating whether to mount the Procharge and breakers high up in the hanging/wet locker in the cabin as this has much better ventilation than the cockpit locker. Have any others mounted a charger in the battery locker or is this a big no no? Any thoughts would be appreciated.
Click to expand...

Regarding the shore power charger: If you are willing to consider an other brand, the CTEK M300 (25 A) is IP44, so damp should not be a problem. But ventilation could still be, if the space is small. I have had a similar CTEK charger in the cockpit locker for 10 years +.
 
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