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12v battery or do i go 6v


Matt&Jo

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I know this has been done to death but i have a specific question id like experience to answer.

 

I am new to this malarky but im okay.....ish with batteries and how to keep them healthy. I know of the different stages ie bulk or abs....now our boat we brought has knackered and i mean shot to bits 4 x 110amph leisure batts so get your wallet out time matt.....

Know do i get a rewire and go 6v trojan t105's x4 aware i may need to mod my batt box or just get 4 x 110amph varta replacements both around £140 a batt......or do i get cheapos and expect to kill them and learn so when i do spend more i practicaly in application make them last.....

 

What ya reckon wonderfluffle forumites?

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It depends on how you use them, how much capacity you actually need, and how you intend to charge them.

 

My experience was 2 sets of el cheapo leisure batteries. Both sets started to lose capacity very quickly, within a few months, despite long cruising days when we were out and on shore power in the marina. But we did use them fairly hard. I rather got the feeling that once the capacity had fallen to 50% it tended to plateau there so if in fact the usage was mostly lights, pumps etc this wouldn’t matter. I changed the first set after about 6 months (but they had been on the boat for a while when it was in build). I managed to scrape 2 years leisure use out of the second, but only with a lot of faffing (regular equalising to restore major lost capacity which eventually killed them)

 

I suspect that people who claim a set of el cheapos lasts 2 years of liveaboard use are very light users and don’t notice a problem until they are down to 25% capacity or thereabout. They tend not to have any means to determine remaining capacity.

 

But as I said we are fairly heavy users. Eg we tend to run the toaster and Nespresso machine in the morning, after a night of boat well lit, recording HD sat box and TV on for hours and in winter, (thermostatic) electric blanket on all night.

 

So we got Trojans, now in their 5th year and still giving as-new capacity. Chalk and cheese and I would never willingly go back to el cheapos. But of course you need to charge them properly.

Edited by nicknorman
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Another argument in favour of going straight for Trojans is if you mess up and let them get sulphated they are recoverable with equalisation, while recovering el cheapos seems to be a lost cause. 

 

DMR seems to find his need equalisation regularly even with proper charging, so don't overlook arranging a way to equalise. It isn't easy to get the proper voltage. DMR resorted to modifying an external alternator controller as there are no products on the market that deliver the voltage required for equalising specified by Trojan. 

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4 minutes ago, Mike the Boilerman said:

Another argument in favour of going straight for Trojans is if you mess up and let them get sulphated they are recoverable with equalisation, while recovering el cheapos seems to be a lost cause. 

 

DMR seems to find his need equalisation regularly even with proper charging, so don't overlook arranging a way to equalise. It isn't easy to get the proper voltage. DMR resorted to modifying an external alternator controller as there are no products on the market that deliver the voltage required for equalising specified by Trojan. 

It depends on which Trojan document you read. I find the 14.5 or so we get from our alternator perfectly adequate in summer and dont need to equalise. In winter it probably isn’t quite enough and I tend to finish at 15v or so (travelpower /Combi). I don’t keep a record but reckon I have only done a “proper” equalise a couple of times in 5 years, but on occasion in winter give it 15.5v for 30 mins or so at the end of the charge.

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Why not go for the 12v Trojans? They are the same size as standard batteries, so no need to mess with the electrics or battery box. I bought one 2 years ago, think it's 105ah, still has its full capacity, more or less. From memory it was 130 quid but might be more expensive now.

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26 minutes ago, Gareth E said:

Why not go for the 12v Trojans? They are the same size as standard batteries, so no need to mess with the electrics or battery box. I bought one 2 years ago, think it's 105ah, still has its full capacity, more or less. From memory it was 130 quid but might be more expensive now.

In the past the 12v ones have been a lot more expensive than the equivalent 2 x 6v cells, although I haven’t checked the prices recently.

 

edit: just checked, around £170 for the same watthours at 12v as you get for £145 at 6v. So less difference than their used to be.

Edited by nicknorman
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I bought 3 x Rolls S-170 from Tayna in May. 390Ah. Just over £500 delivered, (the £38 delivery charge is for a pallet, so covers delivery for several batteries, at least 4). I collected myself, so cost was about £465.

 

I think 4 x T105s are about £650 delivered for an extra 60Ah. You could buy 4 x Rolls for £650, so 520Ah, and they would slot straight into the same space as 4 x Varta normal sized.... 

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8 minutes ago, Mike the Boilerman said:

Another advantage of going 6v is you get only half as many caps to remove and dip, should you like to check the SG of your electrolyte as part of your battery cosseting regime. 

True, and fewer interconnects too.

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18 minutes ago, Richard10002 said:

I bought 3 x Rolls S-170 from Tayna in May. 390Ah. Just over £500 delivered, (the £38 delivery charge is for a pallet, so covers delivery for several batteries, at least 4). I collected myself, so cost was about £465.

 

I think 4 x T105s are about £650 delivered for an extra 60Ah. You could buy 4 x Rolls for £650, so 520Ah, and they would slot straight into the same space as 4 x Varta normal sized.... 

Yes pretty good price. Trojan do seem to be getting very expensive. Rolls are a good make but the claimed cycle life for Trojans is higher, eg around 1700 to 50% DoD vs ~1400 for the Rolls. Although whether manufacturers’ claimed cycle life has any value is a moot point!

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Okay. So im thinking varta are a good brand and about £130ish a battery. They can handle supposedly discharge down to 60% before needing to be charged. Very little saving on a set of t105 but i guess a saving on installation etc....im going to get 12v varta and see what happens. I wont be reading the sg but i want maintenance cells so i can top them up as necessary. Learn by my mistakes and invest in a decent set next time........

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3 hours ago, Mike the Boilerman said:

Another argument in favour of going straight for Trojans is if you mess up and let them get sulphated they are recoverable with equalisation, while recovering el cheapos seems to be a lost cause. 

 

DMR seems to find his need equalisation regularly even with proper charging, so don't overlook arranging a way to equalise. It isn't easy to get the proper voltage. DMR resorted to modifying an external alternator controller as there are no products on the market that deliver the voltage required for equalising specified by Trojan. 

That's not completely correct. I do charge the Trojans at 14.8, or even 15 in winter, but am not very good at getting them right up to 100% charge in winter (when we cruise less) so I am not really charging them correctly. I sometimes go two weeks, or even a month, without doing a real full 100% charge. I therefore rely on an equalisation to sort things out as reckon this is easier than trying to do a full charge every week. I also start the equalisation well before we get to 100% charge as there are not enough hours in the day to do a full charge and an equalisation, but this is mostly because I don't get out of bed early enough ?.

 

I was looking at Trojan prices only yesterday as I really must get some new ones. The original pair date from October 2011 so have done almost 7 years of full time off grid boating. They are now drinking a lot of water. The other 4 date from March 2015 and are still fine.

 

I also had a serious look at Lithiums as they have some big advantages but at present I conclude that Trojans are still the better option. Lithiums are currently too expensive, the chance of a total loss is too great, and I could not get enough capacity into the space available.

 

................Dave 

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18 minutes ago, Matt&Jo said:

Okay. So im thinking varta are a good brand and about £130ish a battery. They can handle supposedly discharge down to 60% before needing to be charged. Very little saving on a set of t105 but i guess a saving on installation etc....im going to get 12v varta and see what happens. I wont be reading the sg but i want maintenance cells so i can top them up as necessary. Learn by my mistakes and invest in a decent set next time........

It will be interesting to see how you get on. Varta are at the upper end of the “el cheapo leisure” market but personally I think they are still chalk and cheese from Trojan or Rolls. I suspect in less than 2 years you’ll be looking for new batteries and you will finally come to realise that the modest extra cost of Trojan, Rolls etc is well worth it!

 

DMR’s 7+ year life of full time off grid boating is a pretty good testament to the longevity of Trojan!

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15 minutes ago, Matt&Jo said:

Okay. So im thinking varta are a good brand and about £130ish a battery. They can handle supposedly discharge down to 60% before needing to be charged. Very little saving on a set of t105 but i guess a saving on installation etc....im going to get 12v varta and see what happens. I wont be reading the sg but i want maintenance cells so i can top them up as necessary. Learn by my mistakes and invest in a decent set next time........

I am not familiar with the Varta but I suspect a set of Trojans will likely last 3 or even 4 times as long so are much more cost effective. It all comes down to the difficulty of fitting the Trojans into the available space and the ability to charge them at a decent voltage. Accepted wisdom is either to get Trojans (or similar), or get cheapos. It might turn out that the Varta are just cheapos at a premium price, the worse of both worlds? Can you give me a link to a data sheet????

 

In my opinion all this stuff about 50% discharge is all a bit of a giant Red Herring. I suspect that all batteries can be discharged to whatever level you choose (well down to 80%) and you are just trading depth of discharge against cycle life, though with better batteries the penalty for going lower might be less severe.

 

.................Dave

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8 minutes ago, dmr said:

 

I also had a serious look at Lithiums as they have some big advantages but at present I conclude that Trojans are still the better option. Lithiums are currently too expensive, the chance of a total loss is too great, and I could not get enough capacity into the space available.

 

................Dave 

Bit surprised about the space comment, I thought lithiums were much more energy dense than LA by volume, especially when one takes into account the ability to use a greater proportion of the capacity.  Or is it just a shape issue?

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1 minute ago, nicknorman said:

Bit surprised about the space comment, I thought lithiums were much more energy dense than LA by volume, especially when one takes into account the ability to use a greater proportion of the capacity.  Or is it just a shape issue?

It might just be a shape issue, I need to work it out in more detail and look at a wider range of Lithiums. But, from a quick look I think lithiums have a lower energy density in volume terms (which is important to me) but a better energy density in mass terms, which is usually not important on a boat or might even be a disadvantage if the batteries are part of the trim ballast.

 

I estimate that comparing Lithiums to Trojans the Lithiums have about 4 times the cycle life but are almost 7 times the price, and weigh in at about 100kg compared to 170kg for the Trojans (for 700Amp-hour). I don't really go along with the concept that a Lithium bank can get away with less amp-hours than lead bank.

 

...................Dave

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8 minutes ago, dmr said:

It might just be a shape issue, I need to work it out in more detail and look at a wider range of Lithiums. But, from a quick look I think lithiums have a lower energy density in volume terms (which is important to me) but a better energy density in mass terms, which is usually not important on a boat or might even be a disadvantage if the batteries are part of the trim ballast.

 

I estimate that comparing Lithiums to Trojans the Lithiums have about 4 times the cycle life but are almost 7 times the price, and weigh in at about 100kg compared to 170kg for the Trojans (for 700Amp-hour). I don't really go along with the concept that a Lithium bank can get away with less amp-hours than lead bank.

 

...................Dave

But a massive advantage for a live-aboard surely has to be the much faster recharge time - the charge current barely tails off as the battery approaches 100% SoC - and the absence of need for daily charging to ward off sulphation. So it is not just about the cost of the product, it is also about the cost and convenience / nuisance value of daily charging. I wonder how many hours of engine running would be saved per day, times 365 (well OK, times the number of static days) times say 20 years, and what the cost of that is in terms of fuel and engine wear not to mention annoyance.

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45 minutes ago, nicknorman said:

Bit surprised about the space comment, I thought lithiums were much more energy dense than LA by volume, especially when one takes into account the ability to use a greater proportion of the capacity.  Or is it just a shape issue?

 

Not that much bigger. Approaching 100% SoC represents a really big risk of wrecking the set. If you hit 100% and charging continues (how confident are you the charger will know, during charging?) then the batteries will probably be wrecked. So charging to 80% SoC is prudent. Maybe 90% if you are sure you know the SoC whilst charging and feel brave. And at the other end discharging to say 20% then starting to charge means you are using only 60% of capacity. 

 

The other approach is to hand it all over to say Victron, RELiON or Valence and pray their integrated management actually works. Every single time ever. 

 

 

 

Oh and another reason not to charge to 90% or more is these cells don't like being stored at over 80%. Not sure why not or what happens if you do. 

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The last time there was a long thread on this I did a back of an envelope calculation based on members experiences with cheap batteries vs my experience with Trojans and to be honest it seemed to be a six and two threes. 

 

But these days I suspect buying cheap and accepting you might have to replace more often makes more sense financially.  I think now we have cheap solar the problems of keeping batteries charged tilts the seesaw towards cheapos. And if you only boat during the "season" I think buying cheap wins hands down.    

 

Personally next time around I'd be tempted to go down the 6v route but only because they are easier to manhandle and I've never had a boat where the batteries were easily accessible (is there such a boat?)  

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57 minutes ago, Neil2 said:

Personally next time around I'd be tempted to go down the 6v route but only because they are easier to manhandle and I've never had a boat where the batteries were easily accessible (is there such a boat?)  

 

I'm just in the process of changing my batteries - the batteries are in the engine room, in front of the engines, they are in a 'well' with 2 in the port-side well, 2 in the centre, and 2 in the Stbd side well, they are below the height of the crawl-way - the front of the engines make getting them in & out very tight, with having to slide them in at a 45 degree angle before fitting the front retaining rail.

 

The big issue is lying on your side, trying to gently lower a 58kg battery at an angle of 45 degrees with one hand without smashing any bits off the engine.

 

Yes - 6X 58 Kgs (Type 625) 230Ah

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