Gel Batteries

[rudolph_hart]

Our boat's present gel batteries are 55AH engine start and 135AH Domestic.

The on-board shore-power charging system is German (as is the boat - Dehler) and is labelled "fur gel batterien".

I suspect both batteries are the age of the boat - 10 years - because, although they are not yet 'cream crackered' they are showing signs of being a bit tired.

I understand that a Domestic (Deep Cycle?) battery has different performance charateristics from an Engine starting battery. However, the boat has 2x electric winches (it's a 'CWS' model) and an electric windlass, which I assume are all powered by the Domestic battery.

Given that the electric winch and windlass motors are all at least as big physically as the engine starter motor, should I consider an 'engine starter' type of battery to replace the existing Domestic?

Also if , for reasons of physical dimensions, I use wet-cell (i.e non-gel) batteries, will this then confuse the on-board charger, owing to possible differences from gel in 'charge-absortion' rates?

Any advice would be most welcome.

 

[steve28]

55ah seems very low for engine start capacity, what sort of engine do you have ?

 

[rudolph_hart]

Yanmar 3GM30 (27HP, 3-cylinder). It was when we put the boat back in, after the charger had been used over winter, that this battery showed signs of being tired. To be fair, we did a lot of cranking to clear air from injectors at that time (changed the fuel filter).

Since then, the engine has had a couple of decent runs, but is reluctant to start initially, and a less-than-rapid crank speed is evident, which could be the cause.

Our 2 previous Dehlers both had 55AH, both Yanmar (one was a 2GM20).

 

[duncan]

I believe that it's the CCA (Cold Cranking Amps) rather than the Ah that will affect the startign performance. The latter will come into it's own after you have been turning over for sometime not the intial attempt. Your experiences suggest that it is a little tired and needs replacing - which at 10 years isn't a surprise!
As an example I have a small spare (relatively) 85Ah / 650CCA battery similar to those used for small diesel vans and it fires up my 240hp Yanmar fine. However the 46 Kg 180 Ah / 1100CCA can do it for longer.......
The electric windlasses will draw a lot of current but not anywhere near the initial draw of the starter motor. To cope with their sustained drawing you will benefit from a good leisure battery with a high'ish rating and a good charging system to keep it topped up.

 

[steve28]

yanmar recomends a 75ah battery for engine starting a 1gm10 engine thats 10 hp engine with a 1 kw starter !

steve

 

[rudolph_hart]

Thanks for the advice on CCA.

The only time either of the electric winches gets any lengthy use is when hoisting the mainsail. By the time the headboard is 'topped' you can hear the winch gradually slowing down (not surprising after a hoist of some 14 metres!)

As the boat isn't marina-based, I will be fitting an Adverc battery management system. I fitted one to my last boat, and the improvement in battery performance was quite impressive.

 

[pvb]

Adverc...

If you're fitting an Adverc, you could really benefit from increasing the size of your domestic battery bank by adding additional batteries. An increased capacity will greatly improve your boating experience if you don't have access to marina shorepower. And, as I'm fond of saying, adding extra batteries is one of the most cost-effective improvements you can make to a boat's electrical system.

 

[rudolph_hart]

Re: Adverc...

Yes, I can see the sense in that idea. However, I'm somewhat strapped for space to put in an extra battery, without locating the extra one at the end of quite long cable runs.

The battery compartment is under the aft cabin bunk, and on the centreline, just aft of the engine, so it also has to accomodate the aft end of the drive train (gearbox flexible coupling, propshaft, Volvo shaft seal and exhaust gurgle box). So the present batteries are really shoehorned in there.

The domestic battery is quite unusual in having both terminal posts at one end of the battery. Without this arrangement, it would be quite impossible to connect or disconnect.

 

[pvb]

Re: Adverc...

Cable runs aren't necessarily a problem. My domestic batteries are located in 2 separate boxes in the aft cabin - one under the port berth, one under the starboard berth.

 

[LeonF]

Re: Adverc...

Hi PVB

My boat has 2 x80AH batteries amidships, port and starboard. The port batt is by the 1,2,both selector switch, and is also the engine start battery. I believe there is a diode in the system. I would very much like to increase the battery capacity but am limited by space. there is none on the starboard side. I could squeeze a smaller batteryin the under berth locker on the port side. Could I link the two existing batteries to form one domestic bank, and get a Red Start or some other similar battery as an engine starting battery ? Would having the domestic bank split P and S cause problems?? And a different kind of starting battery..would that cause probs ??
Many thanks for any suggestions /ideas you may have.

 

[Anonymous]

While I am no fan of gel batteries for cruising yachts, from all you have said, in your position I would replace like for like. If all has worked well for the last 10 years that speaks highly of the setup.

On the other hand, if you are uprating the system to get more domestic Ah then it might be worth considering a 'fast' 'smart' alternator controller such as ADVERC. Then, in my opinion, you would be better off with conventional flooded lead acid. You could go for fairly inexpensive 'truck' batteries if you are a typical season yachtsman who has to fit in his work around his sailing or a dedicated deep cycle battery if you use your boat more, or for longish spells off of shore power.

By the way, it's best not to use the starter to bleed the fuel system as it not only discharges and 'wears out' the cranking battery but cranking for longer than 20 seconds or so can, in some systems, result in cooling water entering the cylinders via the exhaust valves. Very expensive mistake. The fuel pump should have some kind of manual actuator that you operate by hand. It will either be a little lever that you toggle or a 'button' that you push down, I suspect.

 

[pvb]

Re: Adverc...

Leon, what you propose is quite feasible, and wouldn't cause any problems. Doubling the size of your domestic battery capacity is a good idea. You might not need a Redstart, a small conventional battery would probably do the job - remember that most boat engines are tiny in displacement compared with small car engines (a typical 10hp diesel is only about 450cc).

 

[halcyon]

Re: Adverc...

Starter motor loads can remain equal, for quite a big engine size range, there is also a differance between petrol and diesel starting loads. Check your engine specification for starter motor loading and recommended battery size.

Any body remember the Hella smart bolt on regulater from the mid 90's ? retailed for £60 ?

Brian

 

[pvb]

Hella regulator...

Did Hella take over the TWC regulator outfit (Swedish??)? And did Adverc emerge from the guys who'd previously marketed the TWC here?

 

[halcyon]

Re: Hella regulator...

At the time i understood that Hella took over TWC, then Hella stopped making the regulator, then Adverc appeared with the same the operating system as the Hella one.

At the time I was looking at adding the Hella to our range as it looked a resonable priced alternator regulator for boats, Hella were selling it to charge the battery and limit gassing on cars at the time. Hence the dropping to the lower voltage for periods. Next thing I knew was they stopped selling it, then I heard they had bought out TWC, so there ended the cheap regulator.

Brian

 

[LeonF]

Re: Adverc...

Thanks PVB....I shall live with the system this season and upgrade over the winter. Shall spend summer deciding if Adverc is best or I risk the Sterling. Am also considering one of these Dual RCB/mains charger units. Leon

 

[rudolph_hart]

While I am no fan of gel batteries for cruising yachts

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I (naively) believed that, apart from their 'unspillability', gel batteries performed in much the same way as flooded-cell.

The downside seems to be their cost, especialy when flooded-cell seem to be getting cheaper. The present ones are Vetus, which gives them an air of being subject to a 'For-Yachts Surcharge' (excuse pun).

Is there a gel vs flooded cell technical/performance penalty in addition to the 'FYS'?

Also, is there a risk that the on-board shore-power charging system, alluded to in my original post, will charge flooded-cell batteries too slowly/quickly, or does the unit simply adjust charge rate to the level the batteries can take?

Like many owners, I prefer to source OEM spares (oil filters, impellors etc), firsltly because I object to the sometimes-huge cost difference, and also I like the flexibility and convenience of local sourcing.

Flooded-cell batteries fall into this category, making it cost-effective to treat them as a routine 'consumable' on a small yacht, and replace them every 2-3 years, simply for peace of mind.

Despite being on shore-power all winter, the engine battery turned out to be all-but dead when my last boat was craned back in. I was able to obtain a correct sized new one from a local garage, and fit it (in a very cramped comaprtment), all inside 20 minutes.

That kind of quick reation is usually impossible with 'branded' products, let alone heavy batteries ('thank you for your telephone/internet order. You've missd today's delivery schedule, so it'll ship tomorrow and should arrive Monday. Shipping costs will add a further £xxxx + VAT')

 

[Anonymous]

There have been a number of threads discussing this over the last few months and I strongly suggest that you search through them (search for 'gel') as not everyone agrees. I have my opinions which are based on research and knowledge but the real benefit of an open forum like this is the opportunity for others to challenge the information given, or add to it. Though sometimes the information you get is worth exactly what you have paid for it! /forums/images/graemlins/smile.gif

The main downside of gel batteries in cruising yachts is the intolerance to overcharging. All lead acid batteries will gas at the end of charge (gels are lead acid with the electrolyte held in a gel). Gels and sealed lead acid batteries have chemicals inside the cells designed to recombine the H and O back into water but if too much gas is generated at a time, this mechanism is overloaded and the cells vent off. There is no way to put back that lost water. Not ever.

With open flooded lead acids you can put the water back if they should be overcharged for whatever reason. Overcharging is very common, especially with the so-called 'smart' chargers.

 

[halcyon]

One listed differance is life, one firm quotes AGM 3 x the life of standard flooded, Gel 4 x the life of standard flooded. They also maintan charge better.
The other point is that this firm gives a charge voltage for there SLA batteries of 14.7 volt !.

Brian

 

[Anonymous]

[ QUOTE ]
one firm quotes AGM 3 x the life of standard flooded, Gel 4 x the life of standard flooded. They also maintan charge better.
The other point is that this firm gives a charge voltage for there SLA batteries of 14.7 volt !.

[/ QUOTE ]Which firm is that?