Boat service batteries

BlueChip

BlueChip

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On our cruise last week I realised that our 3 x Lucas 113Ah service batteries are not holding their charge.
I just found the original receipt and was amazed to find that I bought them in June 2010 for £92 each, so they don't really owe me anything.

Where are people buying new marine batteries? I'm looking for 2 or 3 maintenance free batteries about 95-110 Ah.
A web search shows lots of resellers with battery brands I've never heard of and sellers with some dubious feedback but branded batteries seem to be very expensive now.

Any suggestions?
 
BlueChip said:
Any suggestions?
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You'll get loads of suggestions, I'm sure. Whilst some will suggest obscure brands at optimistically-low prices, I reckon you can't go far wrong by buying decent branded batteries. My boat came from the factory with Exide AGM Start-Stop car batteries. They seem to be excellent. AGM - so clean, maintenance-free and accept charge readily. Decent brand, so should last well. You can buy these 95Ah batteries for £127 here - https://www.tayna.co.uk/car-batteries/exide/ek950/
 
pvb said:
You'll get loads of suggestions, I'm sure. Whilst some will suggest obscure brands at optimistically-low prices, I reckon you can't go far wrong by buying decent branded batteries. My boat came from the factory with Exide AGM Start-Stop car batteries. They seem to be excellent. AGM - so clean, maintenance-free and accept charge readily. Decent brand, so should last well. You can buy these 95Ah batteries for £127 here - https://www.tayna.co.uk/car-batteries/exide/ek950/
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On Tuesday I bought six Exide AGMs from Tayna - 3 x 100Ah start and 3 x 180Ah house. Excellent service .... I ordered at 3:45 in the afternoon and the batteries were delivered on a pallet at 11:00 am the very next morning. Mind you, a 250kg pallet does take some manual handing when it arrives at the end of your drive. :ambivalence:

Richard
 
When buying batteries do consider the weight of the batteries as you presumably will have to fit them. Hence you can get large capacity 6v batteries at manageable weight. Needs a wire between the 2 but means you get effectively one large capacity battery.
You do need to get deep cycle batteries designed for deep cycle as opposed to those designed for large current engine starting. But for me I would go on price. ol'will
 
I recently had to replace my domestic battery. The non-branded replacement was identical to the branded one that had died. Same case, same weight, same capacity. Obviously, I can't prove it, but I strongly suspect the only difference was the label.
 
William_H said:
When buying batteries do consider the weight of the batteries as you presumably will have to fit them. Hence you can get large capacity 6v batteries at manageable weight. Needs a wire between the 2 but means you get effectively one large capacity battery.
You do need to get deep cycle batteries designed for deep cycle as opposed to those designed for large current engine starting. But for me I would go on price. ol'will
Click to expand...

Really ?

Very few boats that i've seen are fitted with deep cycle batteries.
 
William_H said:
When buying batteries do consider the weight of the batteries as you presumably will have to fit them. Hence you can get large capacity 6v batteries at manageable weight. Needs a wire between the 2 but means you get effectively one large capacity battery.
You do need to get deep cycle batteries designed for deep cycle as opposed to those designed for large current engine starting. But for me I would go on price. ol'will
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I see this quite often on the forum and it’s always puzzled me - what does ol’will mean?
 
richardbrennan said:
I recently replaced my similar batteries with Trojan 31 AGMs from Tayna. Not cheap, but they are true deep cycle.
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Using proper deep cycle batts is a no brainer in monetary terms for people who regularly use them. But if one only does 15-20 cycles per annum, then the cheap and cheerful 'leisure' batts are usually more cost effective.
 
Wet lead acid batteries don't like being deep discharged and it shortens their lives.

A 30ft boat with a fridge, an autopilot, a chart plotter etc. will use around 0,75kWh in a 24hr period if you don't run the engine or charge the batteries. (This comes from measurements of my own typical AWB with the fridge on 24/7). With no fridge it would be around 0,25kWh.

It takes an engine run alternator an hour or two to completely replace that energy.

As a normal lead-acid battery does not like deep cycling, the house bank needs to be big enough for the electrical system. 0,75kWh is just over 60Ah. If 60Ah is only 20% of your total battery capacity (House batteries 300Ah) then you don't have a problem and can run up to around 2 days between charges, if it's 60% (House Bank 100Ah) then you will rapidly kill your house battery because it will regularly suffer deep discharges.

AGM or gel batteries will tolerate deeper discharging so the total capacity can be less than normal lead acid.

Basically, calculate an energy budget based on the equipment on board, decide how many days you go without charging and buy batteries based on energy budget with the maximum affordable capacity that will fit in the space available.
Supplement with solar, wind or any other "free" charging mechanism you can afford.

There is nothing wrong with normal wet lead-acid batteries as house batteries if correctly sized and regularly charged.
 
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BlueChip said:
On our cruise last week I realised that our 3 x Lucas 113Ah service batteries are not holding their charge.
I just found the original receipt and was amazed to find that I bought them in June 2010 for £92 each, so they don't really owe me anything.

Where are people buying new marine batteries? I'm looking for 2 or 3 maintenance free batteries about 95-110 Ah.
A web search shows lots of resellers with battery brands I've never heard of and sellers with some dubious feedback but branded batteries seem to be very expensive now.

Any suggestions?
Click to expand...

I had the same experience with my Lucas battery (LX31MF?), it lasted about 10 years before finally succumbing. Did lots of research that only proved how much mumbo jumbo there is out there. In the end I got the same again hoping for another 10 years. Currently only 2.5 years into that span.

Got mine here...
Free delivery... https://www.batteriesontheweb.co.uk/shop/leisure-batteries/caravan-battery/lucas-leisure-battery-lx31mf-12v-105ah/

Have a look at this https://www.thencc.org.uk/Our_Schemes/ncc_verified_leisure_battery_scheme.aspx
 
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Baggywrinkle said:
Wet lead acid batteries don't like being deep discharged and it shortens their lives.

A 30ft boat with a fridge, an autopilot, a chart plotter etc. will use around 0,75kWh in a 24hr period if you don't run the engine or charge the batteries. (This comes from measurements of my own typical AWB with the fridge on 24/7). With no fridge it would be around 0,25kWh.

It takes an engine run alternator an hour or two to completely replace that energy.

As a normal lead-acid battery does not like deep cycling, the house bank needs to be big enough for the electrical system. 0,75kWh is just over 60Ah. If 60Ah is only 20% of your total battery capacity (House batteries 300Ah) then you don't have a problem and can run up to around 2 days between charges, if it's 60% (House Bank 100Ah) then you will rapidly kill your house battery because it will regularly suffer deep discharges.

AGM or gel batteries will tolerate deeper discharging so the total capacity can be less than normal lead acid.

Basically, calculate an energy budget based on the equipment on board, decide how many days you go without charging and buy batteries based on energy budget with the maximum affordable capacity that will fit in the space available.
Supplement with solar, wind or any other "free" charging mechanism you can afford.

There is nothing wrong with normal wet lead-acid batteries as house batteries if correctly sized and regularly charged.
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That really is a misleading post!
Why do you say wet lead acid batteries dont like deep discharge. I am sure all those using Trojan 105s would not agree. Why do you say AGM or gel will tolerate deeper discharge? Unless they are deep cycle batteries they wont. AGM does not mean deep discharge. Its a type of battery. Of you want deep discharge you need a deep discharge AGM battery.
You dont actually need deep discharge batteries if you have a very large battery bank. Your 60AH nightly discharge would cause no problems to a 1000Ah set of starter batteries used as house batteries. What is a ‘normal’ lead acid battery? I have never seen a battery on a shop shelf labelled ‘normal’
 
geem said:
That really is a misleading post!
Why do you say wet lead acid batteries dont like deep discharge. I am sure all those using Trojan 105s would not agree. Why do you say AGM or gel will tolerate deeper discharge? Unless they are deep cycle batteries they wont. AGM does not mean deep discharge. Its a type of battery. Of you want deep discharge you need a deep discharge AGM battery.
You dont actually need deep discharge batteries if you have a very large battery bank. Your 60AH nightly discharge would cause no problems to a 1000Ah set of starter batteries used as house batteries. What is a ‘normal’ lead acid battery? I have never seen a battery on a shop shelf labelled ‘normal’
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Deep Discharge, Leisure etc. are marketing terms which may give some indication of the intended use of the battery. Fundamentally a lead-acid battery has only a few parameters you can tweak (chemistry, plate design and means of containing the electrolyte - wet, gel, AGM) ... they will never even come close to the properties of a Li-ion in their ability to almost fully discharge and re-charge.

Here is the experience of one Trojan owner for example ...

Why does it seem like we’re always having to replace our batteries? Maybe because we’ve owned the boat almost 15 years and replaced them now 3 times? But when you read the specs online, it doesn’t really seem to matter whether you opt for gel cells, AGMs or flooded lead acid batteries, all of them have lifespans of somewhere between 3 – 8 years.
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http://commutercruiser.com/house-battery-bank-dead-again/

A standard starter battery is designed to produce a high peak current to turn an engine over, typically down to a temperature of -30°C. It is then rapidly re-charged.

AGM and gel can't produce the same sustained high current of a starter battery. My statement that they will generally tolerate deeper discharge is not because of the AGM or gel part, but because they are generally built as service/house batteries ("liesure" batteries) - the technology is uncompetitive in the starter battery market (except perhaps motorbikes). "Deep Discharge" is a marketing label and won't give a lead acid battery Li-ion like discharge/recharge properties - it just means it's a robustly built battery that will tolerate abuse a bit longer - none of them can escape gassing/sulfation problems if they're abused. A "leisure" battery is designed to provide a steady flow of current over a prolonged period and generally doesn't get the instant recharge of a starter battery. Often they spend a lot of time partially charged until either the sun, wind or the user charges them up again. When they are discharged, a recharge must be provided. If left for a long period in a discharged state, or left connected to a load which forces the battery into an over discharged state, no battery will regain its former condition, if it's labelled "Deep Discharge" or not - see the Trojan experience above.

For lead acid batteries, the safest way to avoid battery problems is to have a battery bank that is as large as you can fit/afford, it really doesn't matter what type of technology you employ as long as it is not deep-cycling and is regularly re-charged to 100%.

That was the only point I was making ... you are absolutely right, a 1000Ah bank of plain old "normal" batteries would last for ages on a boat with a 0,75kWh daily energy budget (leisure, deep discharge, starter, golf cart ... it doesn't really matter.) What matters is the quality of construction and as the most expensive part of the battery is the lead plates, then thicker (therefore heavier) is usually better as a house bank. That's what Trojans are, extremely well built bog-standard lead acid batteries whose original design brief was to run golf carts. What label a company chooses to put on it's batteries is generally a marketing exercise and maybe accompanies a tweak to the design.

My house bank was marketed as auxilliary batteries for trucks, I bought them because the construction and price were both good. So far they've been excellent and are showing no signs of degradation after 2 years in service - but then they've never been below 10% discharge and are fully recharged every day.
 
Baggywrinkle said:
AGM and gel can't produce the same sustained high current of a starter battery. My statement that they will generally tolerate deeper discharge is not because of the AGM or gel part, but because they are generally built as service/house batteries ("liesure" batteries) - the technology is uncompetitive in the starter battery market (except perhaps motorbikes).
Click to expand...

If AGM batteries are no good as starter batteries, I wonder why so many modern cars are fitted with AGM batteries as standard?
 
Sailing boats have engine electrical systems resembling cars from about a decade to 2 decades ago - they also tend to have seperate starter and house batteries. A modern car doesn't have the space and can't afford the weight of 2 batteries so opts for AGM as a compromise - they have slightly lower specific energy and higher manufacturing costs.

The start-stop technology in modern cars (primarily to reduce CO2 emissions) is not the only cause for a shift to AGM - due to the increased energy usage in modern cars, bigger batteries are now needed anyway so the AGM compromise isn't as much of an issue.

Basically, the electrical system in a start-stop capable car means the "starter battery" is no longer purely a starter battery and must provide power to the electrical system while the engine is off, it is therefore subject to a much more variable charging regime than was previously the case and has to fullfil the requirements of a starter and a leisure battery at the same time. Given the choice, car manufacturers would fit cheaper wet batteries as before, but wet batteries can't cope with the modern charge/discharge regime as well as AGM can. The AGM batteries fitted to cars are sized as small as they can get away with and are dependent on the vehicles electrical accessory content. More toys = bigger battery.
 
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