Flooded "leisure" or Trojan AGM?

[Yellow Ballad]

I plan on building a new battery tray and fitting a second leisure battery. I was planning on using two "31" sized leisure batteries (Numax XDC31MF) in parallel due to cost and ease of availability but I'm interested to see what peoples thoughts on Trojan T105 sized AGM at twice the price?

My flooded batteries have been fine for my uses so far (pretty light use) but I'm fitting an EV100 tiller pilot, a fridge and heater are on the to do list. At the moment a 50w panel is keeping everything topped up (every other weekend, solar topping up inbetween) plus a but of running the engine getting in and out. I'll probably fit a bigger alternator when the little ones come sailing more and useage increases, probably more solar but no shore power or fancy chargers.

What would you do? I only want to build it once!

 

[peteK]

A larger alternator wont make much difference.

 

[Goldie]

I’d be tempted to build a large enough battery box to cover all options and if you end up with space to spare, use wooden blocks as chocks. If you subsequently change batteries, you should be fine.

 

[lw395]

You either go with your own prejudices, borrow someone else's, or spend a lot of time seriously analysing your predicting use of the boat and cost/benefit of the options. Unless you know you're going to do a lot of cycles, paying extra for batteries with a good cycle life is a punt at best.
Have you considered Lithium?
or maybe Vallium?

 

[James_Calvert]

Consider leaving out the fridge.

Everything else is then easily manageable.

 

[BabaYaga]

I plan on building a new battery tray and fitting a second leisure battery. I was planning on using two "31" sized leisure batteries (Numax XDC31MF) in parallel due to cost and ease of availability but I'm interested to see what peoples thoughts on Trojan T105 sized AGM at twice the price?

My flooded batteries have been fine for my uses so far (pretty light use) but I'm fitting an EV100 tiller pilot, a fridge and heater are on the to do list. At the moment a 50w panel is keeping everything topped up (every other weekend, solar topping up inbetween) plus a but of running the engine getting in and out. I'll probably fit a bigger alternator when the little ones come sailing more and useage increases, probably more solar but no shore power or fancy chargers.

What would you do? I only want to build it once!

If considering AGM's for a new house bank, I would also be looking at the many offerings that are similar in shape to standard, wet batteries.
If space, and especially height, is no problem, follow Goldie's advice.

 

[ryanroberts]

Bigger alternator only really gets used pretty briefly for bulk charge and a lot of cells, or if you have a big inverter and the load for it. Most of the time its going to be siting there putting in a few amps

 

[Stemar]

I'm unconvinced of the advantages of AGM over ordinary leisure batteries for this application, and I don't think LiFePo batteries are cost effective on a cruising boat yet. I expect them to come, but we're no there yet unless you're going for electric power. I agree with the other posters that a bigger alternator will give limited benefits. A smart regulator may be worth while, though.

My first thought for increasing available power would be to increase your solar power. If and when you install a fridge, make sure it's extremely well insulated. The other thing, if you haven't already done it is to fit LED lighting everywhere.

 

[peteK]

A smart regulatoris only worth it if your alternator is not putting out 14.5v.

 

[Yellow Ballad]

Thanks for the replies, it'll be a bit of a pain to make it to fit both types but I think sealed lead acid batteries are the way to go. I only mentioned AGM for the Tojan as I didn't want to be messing about with topping them up.

Thank you for the info on the alternator, I assumed it would get run down batteries back up faster (less engine running time). I'll look into a sterling charger but more solar will be on the cards, plus I have a aquagen for long passages if needs be.

Back to plan A.

 

[pvb]

Thank you for the info on the alternator, I assumed it would get run down batteries back up faster (less engine running time). I'll look into a sterling charger but more solar will be on the cards, plus I have a aquagen for long passages if needs be.

The charging current is determined by the batteries - you can't simply fit a bigger alternator and expect to get more current into the batteries. If you're only having, say, 200Ah of battery capacity, they won't accept a very large charging current. Perhaps your most cost-effective improvement would be to increase the size of the battery bank to 300 or 400Ah. Larger battery banks accept charge more readily, and last longer for a given usage pattern as the depth-of-discharge is less.

 

[Yellow Ballad]

Cheers PVB, I understand they will only take what the need so to speak but I get what your saying. Unfortunately a bigger bank isn't going to really work with the space I have.

 

[duncan99210]

Size matters when it comes to battery banks. I (usually) spend the summers on board and have a 500 amp hour bank, which is about double the size of the original bank I fitted when I left UK to live aboard. Soon found that wasn’t anywhere near big enough so as well as fitting ever more solar I also increased the size of the bank. I use whatever sealed lead acid batteries are available locally when time comes to replace them. I’ve found that they last about 4 years before giving up the ghost.
I don’t have battery boxes, just space under seating where I can fit them, secured by Lidl ratchet straps bolted in place. Even when I’ve cooked a battery the grp doesn’t get damaged by the acid spill, so I’ve never seen the need for boxes. They also limit the size of batteries that’ll fit, which sometimes means having to spend time searching round for ones that’ll fit rather than being able to accommodate the easily available ones.

 

[BabaYaga]

Unfortunately a bigger bank isn't going to really work with the space I have.

The advantage of AGMs vs. wet MF, in theory, is that the former should tolerate a deeper regular depth of discharge without jeopardizing life span.
In other words, more usable AH's for a given battery space/given service life.
Whether this more than pure theory, I don't know.

 

[[70521]]

The advantage of AGMs vs. wet MF, in theory, is that the former should tolerate a deeper regular depth of discharge without jeopardizing life span.
In other words, more usable AH's for a given battery space/given service life.
Whether this more than pure theory, I don't know.

they also cope with vibration better.

 

[pvb]

The advantage of AGMs vs. wet MF, in theory, is that the former should tolerate a deeper regular depth of discharge without jeopardizing life span.

I don't think so - regularly discharging to 50% DoD will shorten the life of most batteries. One advantage of AGMs is that they will accept charge more readily.

 

[ditchcrawler]

I had 2 of the 110a/h sealed Numaxs as my domestic bank and they lasted 8 seasons. They were still OK but I replaced them with the same batteries again as I was going on a longer trip to Holland. I have a Red Flash AGM as my starter battery. I bought mine from Tayna batteries. I have my Sterling alternator management system set to charge at 14.4 volts on the advice of an electrician to suit the sealed batteries and the AGM.

 

[BabaYaga]

I don't think so - regularly discharging to 50% DoD will shorten the life of most batteries. One advantage of AGMs is that they will accept charge more readily.

I based what I said on Exide's guidelines for the wet MF battery that I currently have x 3 in my house bank:
Exide ER350 DUAL Leisure Battery 80Ah (Porta Power PP75)
Those are soon entering their 10th and probably last summer, so I am considering these AGMs as a replacement:
Exide EP650 DUAL AGM Leisure Marine Battery
As can be seen these two batteries from the same manufacturer are practically identical in physical size and Ah capacity.
Their designation, 350 vs. 650, relates to the number of watt hours that can safely be taken out before recharging, "without exceeding the recommended depth of discharge", all according to Exide.
Furthermore, the graph below, also from Exide, compares the number of cycles vs. depth of discharge for those two technologies, the wet MF Dual and Dual AGM.
It suggests to me that to get 250 cycles out of a Dual battery, I would have to limit DoD to just over 50 percent. While I could get the same number of cycles out of a Dual AGM, although it has been cycled down to something like 85 percent DoD.
But maybe this is all theory – I honestly don't know.

 

[pvb]

I based what I said on Exide's guidelines for the wet MF battery that I currently have x 3 in my house bank:
Exide ER350 DUAL Leisure Battery 80Ah (Porta Power PP75)
Those are soon entering their 10th and probably last summer, so I am considering these AGMs as a replacement:
Exide EP650 DUAL AGM Leisure Marine Battery
As can be seen these two batteries from the same manufacturer are practically identical in physical size and Ah capacity.
Their designation, 350 vs. 650, relates to the number of watt hours that can safely be taken out before recharging, "without exceeding the recommended depth of discharge", all according to Exide.
Furthermore, the graph below, also from Exide, compares the number of cycles vs. depth of discharge for those two technologies, the wet MF Dual and Dual AGM.
It suggests to me that to get 250 cycles out of a Dual battery, I would have to limit DoD to just over 50 percent. While I could get the same number of cycles out of a Dual AGM, although it has been cycled down to something like 85 percent DoD.
But maybe this is all theory – I honestly don't know.

So you're saying that the Dual AGM lasts 3 times longer than the Dual? But the Dual AGM costs more than 3 times the price of the Dual. Where's the advantage?

 

[john_q]

I have just fitted 12 volt Trojan Reliant AGM's Group 31's, too early to really report back on how they compare to my previous wet lead acid cells but I can tell you

• They are heavy - around 67 lbs, 30 kgs
• The handles are very thin and painful to use, use a cloth wrapped around the handles
• They are very large Group 31's ,they seem to be a bit wide than any of the other Group 31's I have fitted over the years - one just fitted the custom made battery box