Deep cycle domestic batteries-which ones should we buy?

MikeBz said:
There seems to be contradictory advice on the max charging voltage for AGM batteries, with one website stating that you will destroy them if you use more than 14.2V, whilst others suggest that they can be charged at a slightly higher voltage than a normal lead acid battery. Confusion reigns.
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Quote from Trojan - Equalizing
(deep-cycle flooded/wet batteries only)
Equalizing is an overcharge performed on deep-cycle flooded/wet batteries after they have been fully
charged. Trojan recommends equalizing only when batteries have low specific gravity, below 1.250 or
wide ranging specific gravity, > 0.030 points between cells, after fully charging a battery. Deep-cycle
AGM or gel batteries should Never be equalized
 
JohnGC said:
For the T105s (per 100Ah capacity);
- The lifetime capacity at 30% discharge/charge is 2780 X 30Ah = 83400Ah.
- For 50% discharge the lifetime capacity drops to 1650 * 50Ah = 82500Ah.
- That's a difference of (83400 - 82500) / 83400 = 0.01 or 1%.
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Mostly curious - do you have a reference for those Trojan discharge/life numbers please? Its not obviously on the Trojan website. I didnt have the height for T105s anyway, especially not with the water recycling caps that I looked at. For reference mine are for DMS Red Flash (deep cycle) AGMs, also 6 volt - the GC6s - but I think the numbers are good for the whole deep cycle range. I asked the company for the numbers.
 
Pete7 said:
Those Varta are dual purpose batteries according to Varta. If you are looking for house bank batteries you would be better off with the Varta Hobby series which will discharge to 60% without harm. Notice the extra lead in them compared to the LF 105 (28kgs v 23kgs). Ohand they will still start our Volvo 2003 if we need too.

http://www.tayna.co.uk/813010-Varta-Hobby-Leisure-Battery-A28-P3641.html
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The Varta A28 is available here http://www.amazon.co.uk/Varta-Hobby-Leisure-Battery-813010/dp/B00ANKGGQO for rather less than that, and with a significantly lower delivery charge. (I have no connection other than as a recent customer.)
 
RobbieW said:
Mostly curious - do you have a reference for those Trojan discharge/life numbers please? Its not obviously on the Trojan website. I didnt have the height for T105s anyway, especially not with the water recycling caps that I looked at. For reference mine are for DMS Red Flash (deep cycle) AGMs, also 6 volt - the GC6s - but I think the numbers are good for the whole deep cycle range. I asked the company for the numbers.
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The numbers I have quoted came from a graph on a T105 datasheet and I plugged those into a spreadsheet.

I haven't done this for any other battery; it was an exercise in trying to get a handle on how the T105s behave at different discharge depths. I didn't use the price per Ah in my selection of the T105s, that's just an extension of the analysis.

Since then I have received the figures below in an email from Trojan, my interpretation from the graph was a little off. Trojan's own figures lead to flat lines when you plug them back into the lifetime capacity calculations. IE for T105s depth of discharge has no effect on the total Ah you get from the battery over its lifetime. The rate at which you take it makes a big difference.

PM me if you'd like the spreadsheet; it's in Open Office ods format.

T105.jpg

Here is the %DOD/Cycle:

20% 4000 cycles
30% 2667
40% 2000
50% 1600
60% 1333
70% 1143
80% 1000
100% 800

Self discharge:
@ 42 F - .0015 SG loss per week
@ 75F - .0050 loss per week
@ 86F - .0075 loss per week

No data for capacity/age

 
Many Thanks for all the input and info. Much Appreciated.
In the event, to ensure power over the weekend and Given the service life of the last two Auto Elite 110?s from Harbour Chandlers here in EYH(3years 8months including several deep discharges and 4.5 months Liveaboard last year), we have gone for two more of the same Auto Elite 105ah from them.
£104.95 less10% Club member discount each made them attractive on price, backup if problems, and convenience-
two in the shop, pouring with rain, and help with loading aboard.
Tipping the scales was ;
Use your local Chandler or lose them, and ours will sell you loose nuts, bolts, screws, etc. -and ours is open 6.5 days a week too
 
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I've been following this thread with interest as I am doing a TOTAL refit of all electrics on Evangeline (F&C 44).
The house-bank battery debate has answered some questions but raised many others. New boxes will be needed so no size issue.
Decisions reached so far: Sealed batteries 12V, The smartest charger I can afford, (but should I get a combined charger/inverter or go with separate units??) etc.
Is there a website where the ideal system is discussed/agreed?:confused:
I have read Nigel Calders excellent book many times over but still remain confused.
 
evangeline44 said:
...Decisions reached so far: Sealed batteries 12V, The smartest charger I can afford, (but should I get a combined charger/inverter or go with separate units??) etc.
Is there a website where the ideal system is discussed/agreed?:confused:...
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All I'm going to do is a little more complexity :) Have you considered lithium batteries, LIFEPO4? If youre doing a total refit it might be worth future proofing so that you could slot those in in the future - unless you've money to burn I think theyre still too pricey for most of us (think first born). The advantages seem to be weight and life; something like 30-50% weight reduction for the same capacity, better capacity/life figures - even than the T105s - but hard figures arent easy to get so the cost/benefit seems more a matter of faith at the moment.

I've never come across a single source for the 'ideal system', I think there are generalities but your system is your system and has to match what you think your requirements are going to be. The only way I know to do that is extensive Google searching, then reading and playing with numbers! One key question is consumption - as a liveaboard on the hook in the summer in the Med we use around 150amps/day, as measured by a Link 2000 system. The spreadsheet referred to in post #19, assuming its one I found too, was useful in focusing some of my thinking about usage - I'll try to find a link and post it.

EDIT: Link to spreadsheet pages http://www.vonwentzel.net/Battery/index.html. As these pages were written between 2000-2005 they are now a little dated, they dont address the use of solar charging which is now most cruisers preferred long term solution.
 
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Yes, I think that this does refer to the spreadsheet file I used. I seem to remember that it was a decent enough tool but the hidden data was wildly out for current UK prices 2-3 years ago. I seem to remember that it had a hidden "Data" sheet with details of individual battery models (capacity, dimensions and cost). I modified the data to use UK prices and use a few different models.
 
I had Varta Hobby batts, which were irreparably destroyed by a single dead discharging incident (bilge pump cycling) at less than one year of age. I replaced them with the cheapest Trojan 12v -- only because the superior 6v ones wouldn't fit my battery boxes. These have survived two dead discharge incidents (shore power cord pulled out; can't remember the other) with no ill effect at all. They test better than new after more than 2 years of hard use and the two aforementioned incidents.

Needless to say, I have a very good impression of Trojans.
 
Thanks for the link RobbieW - very concise.
I would like to 'futureproof' and opt for Lithium batteries HOWEVER (as you note) they are still astronomically priced.
Too far for my budget wiv' all the rest of the kit still to buy.

It sounds like we are on the same track as once re-fitted in the UK, we will be living aboard in the Med. so your indication of draw-down sort of equates with my own guesstimates, solar panels will be a certainty as Evangeline is a ketch and couldn't mount a wind generator even if I could abide them! (although looking at vertical mast mount turbines:confused:!)

Thinking of sizing a house bank of 400aH+ to give me some leeway in future.
 
evangeline44 said:
...I would like to 'futureproof' and opt for Lithium batteries HOWEVER (as you note) they are still astronomically priced.
Too far for my budget wiv' all the rest of the kit still to buy...
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It wasnt so much the batteries themselves, I think they've a way to come down in price yet as the market evolves, but if any ancilliaries (chargers etc) come with a 'lithium' setting it might be worth thinking about. I'm not clear if mixed systems (lead/acid & lithium) are even viable given the different charging regimes, it is a technology worth keeping an eye on - IMO. For reference my house bank is 720ah, which helps keep me within the 30% DoD range.
 
Mine is 675Ah, made up of 3 pairs of Trojan T105s.

An alternative option that's worth a look, is to get an EFOY Fuel cell. Then you only need 1 house battery. It's the way I intend to go when the current Trojans bite the dust.
 
EFOY: Methanol powered fuel cell. I considered one 2-3 years ago but had to drop the idea due to high cost of fuel, difficulty of sourcing it plus worry about longevity.

I don't have calcs. to hand but remember that I'd need to carry a lot of MeOH if used as a primary power top-up source instead of a gen-set. I think it was around 1 litre per day to balance usage of about 80Ah/day.

However, it would probably work out OK with my solar/wind setup now as it would just make up the shortfall. Still expensive though at >£3.5k and difficult to get any real tech. data from manufacturer before buying. I think academic papers indicated that I could expect output to drop to 75% within a year and further drop to 50% over next few years. So not great news there either.
 
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