2volt or 12volt batterys

[2cvblue]

I shall have to replace my Domestic batterys soon and would like to know the advantages and disadvantages of using a bank of 2volt batterys, we live onboard and cruise for about nine months of the year. I have a 175amp alternator for domestic and a 2800 inverter.

[Nickhlx]

I shall have to replace my Domestic batterys soon and would like to know the advantages and disadvantages of using a bank of 2volt batterys, we live onboard and cruise for about nine months of the year. I have a 175amp alternator for domestic and a 2800 inverter.

 

 

Just Me will be along soon as he uses them and is into these things... but I can suggest the following :

 

i) they will likely cost somewhat more unless you can find some good ex-forklift or UPS cells somewhere...

ii) you can replace individual cells if one developed a fault - not sure how useful in practice this might be though.

iii) their longevity is likely to be greater if correctly looked after...

 

Nick

[Tony Brooks]

I shall have to replace my Domestic batterys soon and would like to know the advantages and disadvantages of using a bank of 2volt batterys, we live onboard and cruise for about nine months of the year. I have a 175amp alternator for domestic and a 2800 inverter.

 

They will almost certainly have:-

 

a greater cyclic life, possibly 100 times greater like 1500 cycles against 150 cycles. This will make the 50% discharge rule less important in getting a long life.

 

a capacity rating over 5 hours instead of 20 so the effective capacity will be far more than the numbers indicate.

 

The major disadvantage - especially if away from some form of long term, low charge device is that they will sulphate just as easily as the cheap wet batteries but the the greater capacity would tend to hide this to some extent.

 

Unless you run the engine for up to (say) 16 hours a day you will leave your batteries permanently discharged to some degree but to what extent depends upon your electrical use and running hours.

 

I am not persuaded that a long term cruising boat would find the 2V cells cost effective because I feel sulphation will kill them long before they run out of cyclic life.

 

Please do not think a large alternator automatically means your batteries are kept fully charged.

[Justme]

I think most stuff has been covered already.

 

They are likely to cost more but last longer.

 

You will want to look after them better due to the cost.

 

You can charge them at quite high amps.

 

A used ex forklift bank will prob still have plenty of life left for off grid use.

(my current bank cost less than two 100ah 12v bats & has lasted two years so far, I am just about to add in 4 times more capacity which cost about half the first lot per ah, so I will have a 4300ah 5C 12v bank for about £600)

However as old bats now have a value of nearly £500 per tonne the price of used forklift banks is rising if you can get one.

(both my banks together prob weigh about 1800kg so even when no more use I will get back more than I paid for them)

 

If you have a specific question ask away.

[Arnot]

They will almost certainly have:-

 

a greater cyclic life, possibly 100 times greater like 1500 cycles against 150 cycles. This will make the 50% discharge rule less important in getting a long life.

 

a capacity rating over 5 hours instead of 20 so the effective capacity will be far more than the numbers indicate.

 

The major disadvantage - especially if away from some form of long term, low charge device is that they will sulphate just as easily as the cheap wet batteries but the the greater capacity would tend to hide this to some extent.

 

Unless you run the engine for up to (say) 16 hours a day you will leave your batteries permanently discharged to some degree but to what extent depends upon your electrical use and running hours.

 

I am not persuaded that a long term cruising boat would find the 2V cells cost effective because I feel sulphation will kill them long before they run out of cyclic life.

 

Please do not think a large alternator automatically means your batteries are kept fully charged.

Actually in practice although the advantages hold, the disadvantages you percieve are not bourne out in reality in my experience. It sounds like the OP has a Beta 43

 

As it happens I carried out a 2v cell installation for a couple who use their boat similarly and because of the low impedance of the cells, the high output of the alterantor could be maintained for longer and replenish the battery quite quickly up to 85% ish. What they have experienced is that during the two or three hours cruising they do most days they can more than top the battery up to a level whereby if they do want to moor up for a day or two they then don't need to run their engine for battery charging. This has resulted in a drop of about 40% in fuel usage according to the records they keep.

 

Obviously any battery left discharged for long periods will sulphate but again the pracitcal experience is that this is less servere than with leisure batteries.

 

The cells I used were a custom 600Ah low profile traction cell which seem to fit into the swim location used in many boats and tend to suffer less from stratification.

 

I think I am persuaded but in 20 years we should know for sure...

 

Regards

 

Arnot

[WotEver]

I think I am persuaded but in 20 years we should know for sure...

I'll check back with you then.

 

Tony