Which AGM (gel) battery to buy?

I wouldn't worry about the maker's spec too much. You don't 'need' gel or AGM, but check the mains charger if there is one as it may have settings for different types.
For the engine, anything that can put out the required CCA for a suitable period will do the job. You might want excess capacity as a house backup though.

For house battery, simply get the highest capacity decent quality that will fit in the box Yuasa commercial vehicle batteries are worth a look - see YBX range.
 
Those are standby batteries, they're not designed to be cycled and will fail prematurely if they are.

http://news.yuasa.co.uk/wp-content/uploads/2016/05/LIT_038_Yuasa_Industrial_Range_Web_2017.pdf

Interesting. I had two Yuasa 24 AH industrial standby batteries from a backup system for a computer set up.

They were changed twelve years ago for replacements at my place of work. They were then five years old. So, one is seventeen years old.

One is kept in my workshop for a portable 12v feed. The other was fitted in a sidecar when the battery of the motorbike pulling it failed. It was used weekly for six years before it died. At 11 years old.

A friend was a lift engineer. He supplied me with Yuasa emergency stop batteries which I used for total loss coil ignition on my longtrack bike, a Hagon - JAP Sandracer. When not on the bike they were dropped into a special holder under the race trucks seat and charged by a pair of jump leads from the trucks battery/charging system. That truck averaged 30,000 miles per year.

I never had a DNF from a bad battery. In fact, never had a mechanical failure, just falling or becoming filled in with sand and subsequently blind.

Yuasa advice might be as you say.

But they have certainly survived a regular charging routine in my use of discarded ones.
 
I did look into various battery technologies when refitting mine. Obviously lithium is the best at the moment but for £500-700/battery its ridiculous. Even diy-ing a lithium battery is expensive. AGM are ok but not that different to sealed lead acid. I went for the latter and too be honest they work well. Boat s more or less self sufficient during summer with the solar generated and the odd engine run. Winter it just needs more engine runs but still good. I went with 2 x 125ah hankook house & 1 x 75ah hankook engine. 2 way VSR so charges all from engine alternator and the other way round via solar connected to house. Reason being the coast of other technologies doesn't really warrant the benefit of just putting in new sealed lead acids every 3-5yrs.
Imagine spending £2000 on lithium batteries and then have an incident where you have water ingress that floods them!!
 
Interesting. I had two Yuasa 24 AH industrial standby batteries from a backup system for a computer set up.

They were changed twelve years ago for replacements at my place of work. They were then five years old. So, one is seventeen years old.

One is kept in my workshop for a portable 12v feed. The other was fitted in a sidecar when the battery of the motorbike pulling it failed. It was used weekly for six years before it died. At 11 years old.

A friend was a lift engineer. He supplied me with Yuasa emergency stop batteries which I used for total loss coil ignition on my longtrack bike, a Hagon - JAP Sandracer. When not on the bike they were dropped into a special holder under the race trucks seat and charged by a pair of jump leads from the trucks battery/charging system. That truck averaged 30,000 miles per year.

I never had a DNF from a bad battery. In fact, never had a mechanical failure, just falling or becoming filled in with sand and subsequently blind.

Yuasa advice might be as you say.

But they have certainly survived a regular charging routine in my use of discarded ones.

Using it as a starter battery on a motorbike isn't cycling it - the discharge caused by starting is minimal. Yuasa's specs say that standby batteries shouldn't be discharged by 30% more than 2 or 3 times a year, which basically makes them useless for most boat applications.
 
Using it as a starter battery on a motorbike isn't cycling it - the discharge caused by starting is minimal. Yuasa's specs say that standby batteries shouldn't be discharged by 30% more than 2 or 3 times a year, which basically makes them useless for most boat applications.
Yuasa are spec'ing these batteries to achieve a 10 year life.
If you want 10 years with a certain capacity at the end of it, you can't expect to cycle the batteries often.
A lot of 'back up' batteries are spec'd that way, because that is what the users need, in alarm systems, computer uninterruptible supplies etc.
Lots of people have used such batteries in cycled applications and had reasonable life. The battery chemistry is not wildly different.
If they were cheap enough they might be cost effective.
I had a couple of ex-telecoms backup batteries on a yacht, they performed OK despite already being 8 years old. They were certainly cost effective.
I suspect Rotrax's bike didn't have a starter and the battery was running an ignition system with no charging?
 
Those are standby batteries, they're not designed to be cycled and will fail prematurely if they are.

http://news.yuasa.co.uk/wp-content/uploads/2016/05/LIT_038_Yuasa_Industrial_Range_Web_2017.pdf
I’ve seen that said before and in the battery literature. On the other hand, our boat’s original 2x200ah Banner Stand By Bulls lasted 7 years under the original ownership which included transat and Caribbean cruising. We replaced like with like, mostly because they were the only way we could get max ahs into the very tight battery box, and now have 6 years on them including a year on a mooring and 3 x 7 months in the med mostly at anchor, so often not fully charged, and they are still doing fine. So may not be ideal, but at the right price might be worth a look.
 
I’ve seen that said before and in the battery literature. On the other hand, our boat’s original 2x200ah Banner Stand By Bulls lasted 7 years under the original ownership which included transat and Caribbean cruising. We replaced like with like, mostly because they were the only way we could get max ahs into the very tight battery box, and now have 6 years on them including a year on a mooring and 3 x 7 months in the med mostly at anchor, so often not fully charged, and they are still doing fine. So may not be ideal, but at the right price might be worth a look.

Banner use the "Stand by Bull" designation on a wide variety of batteries, not all of which are pure standby batteries. Some are designed for small traction applications. If yours are working well in cyclic application, they're unlikely to be pure standby batteries.
 
Yuasa are spec'ing these batteries to achieve a 10 year life.
If you want 10 years with a certain capacity at the end of it, you can't expect to cycle the batteries often.
A lot of 'back up' batteries are spec'd that way, because that is what the users need, in alarm systems, computer uninterruptible supplies etc.
Lots of people have used such batteries in cycled applications and had reasonable life. The battery chemistry is not wildly different.
If they were cheap enough they might be cost effective.
I had a couple of ex-telecoms backup batteries on a yacht, they performed OK despite already being 8 years old. They were certainly cost effective.
I suspect Rotrax's bike didn't have a starter and the battery was running an ignition system with no charging?

Yup - thats what 'total loss coil ignition' means.

Always put a fresh one in for the final though.

I have five 110AH AGM Lifelines on our Island Packet SP Cruiser. When I fitted the Genset three seasons ago I used a cheapo 110 spiral wound AGM. A third of the cost of a lifeline.
The voltmeter can check the voltage on each of the three battery systems, starter battery for the genset, ditto the engine and then the four in the house bank. All of the voltages are above 12.6 unless the house bank has had a bollocking for a while.
Not very often as we run the genset - 8KW - daily for an hour to charge batteries and heat water. Both starter batteries tend to show 12.8 or 12.9 pretty constantly at rest.
 
It says in the book, Applications • UPS • All other high rate discharge applications
They are good at deep drain recovery. I would say they are fit for use on a boat but happy to be corrected.

But they're not intended for repeated deep cycling. As I quoted before, Yuasa say 2-3 cycles a year if you're discharging by 30%. Most domestic batteries on boats get cycled much more than this.

I appreciate that you're trying to sell them, but you shouldn't misrepresent them.
 
But they're not intended for repeated deep cycling. As I quoted before, Yuasa say 2-3 cycles a year if you're discharging by 30%. Most domestic batteries on boats get cycled much more than this.

I appreciate that you're trying to sell them, but you shouldn't misrepresent them.
I have an idea, if the chap who asked question is local he is welcome to come and collect two for his boat, if they are still working ok in five years time he can pop back and donate what he feels fair for the batteries . I would rather someone has some use for them than keep tripping over them in the basement :)
 
I have two on our Kiwi boat, a Hartley 32 in steel.
Topped up by a little solar - 40 w - when we are in the UK, they were from a computer back up bank replaced for compliance with insurance co. rules at five years.
Still working good four years on.
Habit makes us frugal with DC electricity, so perhaps they dont deep cycle.
But, they stay charged with the use we give them, they cost $150 NZ - about £80 - for two used but good 90AH AGM Yuasa industrial jobs.
The guy who put me on to them has six on his boat. He lives aboard full time - his boat is his home, it has lots of bells and whistles.
His were fine when we left in late April.
True knowlege is, perhaps, the product of direct experience.
 
I have two on our Kiwi boat, a Hartley 32 in steel.
Topped up by a little solar - 40 w - when we are in the UK, they were from a computer back up bank replaced for compliance with insurance co. rules at five years.
Still working good four years on.
Habit makes us frugal with DC electricity, so perhaps they dont deep cycle.
But, they stay charged with the use we give them, they cost $150 NZ - about £80 - for two used but good 90AH AGM Yuasa industrial jobs.
The guy who put me on to them has six on his boat. He lives aboard full time - his boat is his home, it has lots of bells and whistles.
His were fine when we left in late April.
True knowlege is, perhaps, the product of direct experience.

If yours don't deep cycle, they should be OK.

As for true knowledge (sp), it also involves buying the right products in the first place. Whatever people say, standby batteries are no good for repeated deep cycling.
 
If yours don't deep cycle, they should be OK.

As for true knowledge (sp), it also involves buying the right products in the first place. Whatever people say, standby batteries are no good for repeated deep cycling.

The right products for me with my cheapo Kiwi boat were products at the right price.
Deep cycle leisure batteries were 600 bucks a pair, I paid 150.
For use where the boat is idle in its berth 7 months or more each year what I use appear to be perfect.
The far more sophisticated and expensive UK boat has the OE make and spec batteries, bar the genset starter battery.
That appears to work good too.
 
I am medway based . If your interested I have four of these, they are a couple of years old but not used, they were for a solar power system that never got installed. SWL3300FR
I have two on my boat and a 55w solar panel keeps them topped up, I use a split charger from the engine and a different controller for two banks from the solar as the engine battery is standard type. It all works well and they are all always fully charged.
They cost about £200 each but selling for £50 as I have no use for them.
Only just seen this but thanks for the offer
 
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