EFB Leisure battery

[alahol2]

Our 'House' battery is dying. We only have one 100Ah leisure battery as our 'House' bank. An 85Ah leisure for the engine provides a little bit of reserve. A 30W solar panel (usually) gets them up to full charge during the week.
Since I last went through the replacement exercise it seems that EFB Leisure batteries have come onto the market.
The blurb says that they can accept charge faster and have better deep cycle characteristics than 'standard' leisure sealed lead acid batteries. Both characteristics sound desirable.
Pricewise, the EFB are only marginally more expensive than standard SLA.
This is the one I'm looking at... Yuasa M31-EFB

Anyone any experience/knowledge? Is it worth the (small) premium?

 

[[70521]]

Personally, I'd install an AGM over a EFB as a replacement for about the same price . You might find a 130 AH battery of the same physical dimensions as your existing one.

 

[KompetentKrew]

From Yuasa's site:

Q. What are the differences between EFB and AGM batteries?​

A. EFB batteries have been introduced as a lower tier option to AGM batteries in terms of performance and durability. EFB technology relies on improvements to existing flooded technology through the addition of Carbon additives in the plate manufacturing process. AGM batteries benefit from the inclusion of unique design features not found in wet-flooded batteries.​

EFB batteries seem to be designed for cars with the stop-start feature, and I don't see the benefits for your purposes - if you do primarily use the boat at weekends, and it does indeed get 100% charged over several days between uses then higher charge acceptance isn't going to be much benefit.

High charge acceptance would be useful if all your charging was done whilst motoring, for example, because it would maximise the charging achieved when leaving the mooring or the marina.

In light of your usage I would have thought the best solution would be to spend your money on the highest capacity lead acid batteries you can get for your money,.

I'm surprised you can manage with only 100Ah, and I am happy to spend your money on a more substantial solution. Do you know how deeply you cycle the current house battery?

 

[alahol2]

The majority of our sailing is done each weekend for (usually) 3 days, back on Monday. If the weather looks good we will go off for a week maybe two. We are permanently 'off-grid'. When the house battery is in good condition we can last about 5 days without needing to re-charge although we would normally move in that time which means, at least some, motoring thus there would be some re-charging (as well as a small amount from the solar). The better charge acceptance would be a definite help in this scenario.
All lamps are LED, entertainment is the radio and Buetooth music, no fridge so the battery capacity is not normally a problem to us. We probably don't get to more than 30 - 40% DOD.
The Yuasa EFB is about £10 more than replacing our current battery like for like (Lucas LX31MF).

Has anyone got a reason NOT to use EFB?

 

[Tranona]

No reason not to, but as already suggested for very little more you can fit an AGM for even longer potential life, faster charge and lower self discharge. These are what I will be fitting tayna.co.uk/car-batteries/exide/ek950/ I have 5 of them in my current boat (3 in house bank) now 6 years old and still performing well.

As explained EFBs are in between standard LA and AGMs, but the price differential has shrunk since they were introduced and it now makes little sense to buy them. They are probably still available only because of demand from cost conscious car makers!

 

[PaulRainbow]

I'd also go for the AGM option.

 

[alahol2]

These are what I will be fitting tayna.co.uk/car-batteries/exide/ek950/

I thought for a minute you had found something I had missed. Unfortunately the space for the battery is absolute max length of 330mm and that one (at 353mm) just won't go in the space. The cheapest type 31 AGM (which has to be shoehorned in) I can find is closer to £200 than £100.

 

[Porthandbuoy]

I was under the impression you couldn't just drop in AGM batteries instead of LA, or EFB, without changing all your battery charge voltages to suite. eg. Alternator regulators and mains chargers.

 

[alahol2]

As I understand it, EFB uses the same settings as SLA. AGM can take higher charging voltage levels but they are not imperative.

 

[Tranona]

I thought for a minute you had found something I had missed. Unfortunately the space for the battery is absolute max length of 330mm and that one (at 353mm) just won't go in the space. The cheapest type 31 AGM (which has to be shoehorned in) I can find is closer to £200 than £100.

There is always an "ah but" which kills it! On my project boat I have just enough room to build a battery box that will take 2 Exides, but then not enough room for a conventional starter battery, so will be using a Red Flash. Expensive but gives me what I want without building another box in a different location for the start battery.

Given the space constraint the EFB is the logical choice - better value than the leisure battery.