12v or 6v house batteries

[Nostrodamus]

My house batteries have lasted us pretty well as full time liveaboards spending a lot of time at anchor (all summer)
It is now time to change them and I am slightly confused.
We have 4 x 260 amp our batteries which are six volts.
We need more battery power if possible.
What is the best way to get as much power storage as possible?
would it be to go with 4x 6v batteries of 260amp hours or to get 4 x 12v batteries.
The batteries we have are normal wet cell batteries which seem to be the best value for money and as we have a very limited budget we will go the same way.
Are the better know batteries genuinely better than cheaper less well know brands.
Thank you for any advice.

 

[KellysEye]

6 volt batteries are wired in series to give 12 volts. If you have 6 volt they are probably deep cycle batteries that should be used for house batteries. The most popular are Trojan T105s. As with everything you get what you pay for, don't go the cheap route when house batteries are involved.

 

[sarabande]

if your boat systems are 12v, go for 12v batteries.

12v gives you more watts per amp than 6v, and the batteries are more easily available and replaceable. For the same 'volume' of batteries in the battery compartment, you will have - very roughly - twice the amount of power available from 12v than 6v. It is likely that you will need more battery space for 4x12v, than 4x6v.

You will need to re-route some of the battery connection leads though to parallel rather than series-and-parallel.

 

[Nostrodamus]

6 volt batteries are wired in series to give 12 volts. If you have 6 volt they are probably deep cycle batteries that should be used for house batteries. The most popular are Trojan T105s. As with everything you get what you pay for, don't go the cheap route when house batteries are involved.

Thank you Kellyseye.. Is it best to stay with 4 6v or change to 4 12v...?

 

[Nostrodamus]

if your boat systems are 12v, go for 12v batteries.

12v gives you more watts per amp than 6v, and the batteries are more easily available and replaceable. For the same 'volume' of batteries in the battery compartment, you will have - very roughly - twice the amount of power available from 12v than 6v.

You will need to re-route some of the battery connection leads though to parallel rather than series-and-parallel.

The re routing shouldn't be a problem at all. I just wondered why the put 6v originally rather than 12v ?

 

[sarabande]

Job lot of golf cart batteries or from the UPS system of a data centre ? ? Quien sabe

 

[Mistroma]

if your boat systems are 12v, go for 12v batteries.

12v gives you more watts per amp than 6v, and the batteries are more easily available and replaceable. For the same 'volume' of batteries in the battery compartment, you will have - very roughly - twice the amount of power available from 12v than 6v. It is likely that you will need more battery space for 4x12v, than 4x6v.

You will need to re-route some of the battery connection leads though to parallel rather than series-and-parallel.

Could you give some more data to back this statement?
12V will certainly give more watts per amp. However, you then jump to a conclusion that you'll get "twice the amount of power available" from 12V vs. 6V having same volume.

I'd expect the energy density to be similar, assuming 6V & 12V are using the same chemistry. I'd expect capacity in Ah to be similar if we are talking about output at 20-100 hour rate.

A quick comparison of Trojan T105 (6V) vs. Trojan 27TMX (12V) shows following:

2xT105s 225Ah@12V Volume 0.0264 cu.m
2x27TMX 210Ah@12V Volume 0.0275 cu.m

So no big difference between 6V & 12V in volume.

 

[Mistroma]

The re routing shouldn't be a problem at all. I just wondered why the put 6v originally rather than 12v ?

T105s are widely thought to give the best bang-per-buck. Other Trojan 6V models may give more Ah but increased cost outweighs the gain. T105s are probably their biggest seller and so you get a better price.

It is certainly the case that 12V Trojan batteries are not expected to survive same number of cycles as 6V range. Trojan's own data shows deep-cycle 6V range last 2xcycles of 12V "deep-cycle" range.

I'm only discussing flooded lead deep-cycle batteries, not AGMs, leisure etc. In that case, T105s are difficult to beat for value and reputation. Probably available for around 150 Euro per battery.

 

[Richard10002]

Trojan T105 £107.50 delivered from Battery Megastore.

http://www.batterymegastore.co.uk/product/T105/?ref=bmuk&gclid=CJPP7-Snkr4CFTMetAodUywAHQ

Probably slightly more expensive from Tanya.

 

[Nostrodamus]

Thank you for this information.
Currently i am in Sicily so most companies do not ship here or it is to expensive. They do sell Trojan batteries here though.
So are you saying that 6v would probably be better and will I get the same amp hours out of 4 x 6v batteries as I would out of 4 x 12v batteries if they were the same rating?

 

[TQA]

if your boat systems are 12v, go for 12v batteries.

For the same 'volume' of batteries in the battery compartment, you will have - very roughly - twice the amount of power available from 12v than 6v. l.

This is not the case. A 12 volt 225 amp/hr battery is approximately twice the size of a 6 volt 225 amp/hr. Check battery spec sheets for case sizes.

As others have said the standard golf cart battery, the ubiquitous Trojan T105 is the battery of choice of many in the cruising world. I have 6 configured to give me a single bank of 12 volts 675 amp hours. Yes they need topping up with water on a regular basis. Mine take about 2 pints every 2 weeks. I expect them to last 4 years with every year beyond 4 seen as a bonus. The type of battery construction used in the T105 withstands repeated deep cycling better than a typical 'leisure' battery.

The OP does not give a location so I can only give my experience. T105s are available at around $125 in the USA and $200 in St Maarten.

 

[Rigger Mortice]

So are you saying that 6v would probably be better and will I get the same amp hours out of 4 x 6v batteries as I would out of 4 x 12v batteries if they were the same rating?

Not really. If each of the batteries is, say, 100AH, you will get half the power from the 6volt set up.
(100ah@6voltsx4=2400watts. compared with 100AH@12voltsx4=4800watts)

If you want to compare like with like you should be looking at 4x6volt batteries, or 2x12volt batteries

Two questions then remain a. Which is the better battery? b. What space is available?

If the Trojan 6volt is the better deep cycle battery (and it is certainly the only one that I have seen consistently recommended) then, for a live aboard, it's probably the best choice.

 

[parbuckle]

It would be interesting to know what age your batteries are as it is useful for potential buyers to get an idea as to wether they are a good investment I would expect them to go on for 6 to 10 years as an everyday battery should go 2 to 3 years also what are the failure symptoms are you testing each cell with a hydometer and one has failed or has the overall performance become very poor . These type are used in forklift trucks that are charged daily and should give years of service hence high price .

 

[Jean]

Also need to be sure what voltage your load side takes, simply by checking how the batteries are wired together, as different combinations of connection options can give 6, 12 or 24 volt outputs, and whilst likely 12 volt, it's worth checking to be sure.

 

[nigelmercier]

A 12 volt 225 amp/hr battery is approximately twice the size of a 6 volt 225 amp/hr...

First of all, it isn't amp/hr (which is meaningless) it's amp-hr or normally Ah.

As you say, there is no advantage of size: a 12V 225 Ah battery is essentially two 6V 225 Ah batteries wired in series in a double sized case. Unless 6V batteries are readily available locally, I'd swap to 12V to reduce the number and complexity of connections.

 

[Deleted member 36384]

It would be interesting to know what age your batteries are as it is useful for potential buyers to get an idea as to wether they are a good investment I would expect them to go on for 6 to 10 years as an everyday battery should go 2 to 3 years also what are the failure symptoms are you testing each cell with a hydometer and one has failed or has the overall performance become very poor . ......

I have 4 x 6V Trojan's for my 24V system which are at least 7 years old and still going well. I have a bit more of a risk compared to 12V systems, if one goes I lose my 24V domestic power. One of my batteries needs topping up more than the other.

 

[Trident]

I have several Trojan 105 6v wired to give 675 Ah at 12v

These should last 15 years if treated right and so far have not needed any water top ups at all - I have very large solar panels and wind gen so even with several cloudy days in a row I've never taken them much below 80% charge which is the secret to making them last. Do remember that any battery when run down below 50% is essentially flat and will not power your systems - but ultra deep cycle batteries like the Trojan are designed to be run down that low and charged up again time after time whilst many "normal" leisure batteries can only stand relatively few deep discharge cycles. The Trojan 105s are 225 Ah each and each one is about the same size as a 100 Ah 12v - thus as you need two to make 12 v you have 225 Ah at 12 v for the same physical space as two 100 ish 12v batteries that make 200 ish Ah. So all in all there seems no better option than the Trojan T105s and I have been very happy with mine...

 

[William_H]

The question of which battery you fit is a function of what is available at what price. Do remember that 6v batteries are half the weight of the equivalent AH rated 12v battery. Indeed this is why 6v batteries are made becuase in large capacity it is more physically manageable. As said 2 6v 100AH batteries will be just slightly larger than one 12v 100AH so no real difference. good luck olewill

 

[Nostrodamus]

Thank you to every one for their help and advice. Looking at the options and room available I think the best thing for me would be to go with the T105's 6v and increase the batteries from 4 to 6 to give me the extra power.
Again thank you for all your replies and advice.

 

[charles_reed]

Thank you Kellyseye.. Is it best to stay with 4 6v or change to 4 12v...?

I'd agree that the Trojan 6v batteries are probably the "best" you can get.
However, capacity = volume available, so it's likely that you'll get in more amp-hours using 12v batteries, but if you do that you'll have to rewire. A circular argument...

My experience is that the cheapest, open-cell, lead-acid batteries have the lowest total cost of ownership - You'll be able to replace them 3 times for one replacement cycle of the Trojans and there's little to be gained by using a "named" brand, where you get stung for the name. When in doubt go for the heaviest you can get, there's no substitute for lead.