Batteries?

[skipmac]

Originally Posted by Chris777

Looked at Golf -Batts (6V) I really like the idea..... BUT they wont fit, my batt box have a hight limit of 9 3/4" and there is no pracvtical way to deepen it. So I am back to Grp 31's. I cant find any wet cell batts that compare to the grp-31 AGM's amp capacity. I like to get a batt bank of 500-600 amps, the AGM's will more than cover that. I can fit 4, but maybe 3 will be enough. All my lights, nav, interior, mast top, etc is LED. Really only draw when under sail is the fridge and plotter, depth and speed...

Hi Chris.

Sounds like you're stuck with what you can fit.

Depending on the size, insulation and ambient temps your fridge could draw as much as 50-60 amp hours/day. If no AP, not running a stereo or any other high draw gear as a wild guess, under 100 amp hours/day. Have you don't an energy audit to confirm?

Regardless, as mentioned AGMs do have some shortcomings for boat use, especially if you are usually off the grid. If you are at a dock for a few days a few times each month and can plug in to fully charge the batteries you will probably do OK.

The problem with AGMs is they don't like to be left in a partially charged state for long periods and really like being fully charged on a frequent basis. The more you can follow these guidelines the longer the batteries will last. If you can't you may lose a set of expensive batteries in just a couple years.

[john61ct]

Good G-31 FLA:

US Battery 31DCXC

Crown 31T-1000

Deka / Duracell SLI31MDC


Not as good value as GC but better than going AGM unless you really need to

[Paul L]

Originally Posted by Chris777

Looked at Golf -Batts (6V) I really like the idea..... BUT they wont fit, my batt box have a hight limit of 9 3/4" and there is no pracvtical way to deepen it. So I am back to Grp 31's. I cant find any wet cell batts that compare to the grp-31 AGM's amp capacity. I like to get a batt bank of 500-600 amps, the AGM's will more than cover that. I can fit 4, but maybe 3 will be enough. All my lights, nav, interior, mast top, etc is LED. Really only draw when under sail is the fridge and plotter, depth and speed...

A significant advantage to AGM batteries is that they can be installed on their side. In tight boxes this can sometimes make a big difference to how many ah you can fit in.

[john61ct]

Yes, that's the best reason to pay the premium and sacrifice all the other benefits of FLA.

Need to be a lot more careful with them to get good longevity, more precise charging parameters, higher amp rates, more important to avoid over discharge and PSOC abuse, etc.

[Chris777]

Ok.... More questions. As I have stated above I am limited in my battery compartment to any thing less than 9 3/4" height. I can fit 4, Group 31, AGM or FLA. However I can fit 3 Group 31 FLA @105 amps each and 3 Group 24 FLA @75 amps each. This combo will maximize my batt comp....... BUT is it compatible to have these 6 batts wired in series for a total amp of 540 amp and 12 volt?

If not I will have to go with the Trojan Grp 31 overdrive at 180 amps each..... unless someone has a better idea.

I charge with a 100 amp alternator, 315W solar panel to be instaled shortly and shore power.

Starting battery is totally separate so we are only talking about "house".

36' Sailboat.

Thanks,

Chris

[hellosailor]

AFAIK if you are putting different capacity batteries in series, every time you draw down the bank the bigger cells will be able to discharge to, say, a 70% state of charge, while putting up the same power may take the smaller batteries down to a 55% SOC. So you will be wearing out the smaller batteries. It will work, it will just consume out set faster than the others, and as that continues, the difference in consumption rates will grow.

You'd have to consider that as opposed to having less capacity overall and cycling a smaller bank more heavily as a result of that. If it helps, remember that AGM and gel can be installed on their sides. Maybe that makes something fit?

[Chris777]

Thanks "Hellosailor". Just what I wnted to know..... even thou it wont work. I think I will just bite the bullit and go with the "overdrives".

Cheers

[zboss]

Originally Posted by Paul L

A significant advantage to AGM batteries is that they can be installed on their side. In tight boxes this can sometimes make a big difference to how many ah you can fit in.

This is true. We ended up putting our fireflys on their bottom but we could have put them “end up” and expanded our box only a few inches, doubling our capacity. In the end, we are perfectly fine with the price we paid not to have to be concerned with all the issues mentioned in this thread about AGM or FLA.

[john61ct]

Do not put unlike batteries together in a single bank.

Link to the Trojans you're considering?

[Chris777]

Jihn61ct,
Reliant AGM | Trojan Battery Company

Very bottom of page

OverDrive AGM 31™
180

[john61ct]

Originally Posted by Chris777

Jihn61ct,
Reliant AGM | Trojan Battery Company

Very bottom of page

OverDrive AGM 31™
180

So this? http://www.trojanbattery.com/product/31-agm/

Personally unless they're 30+% cheaper including the driving/delivery factor, I'd stick to Odyssey Lifeline or Northstar.

There just isn't enough experience out there with Trojan's AGM over time to see how long they last in real world usage.

But just my 2¢, obviously do what you want.

And sorry to harp, but I must have missed why you think you need sealed?

Originally Posted by john61ct

Good G-31 FLA:

US Battery 31DCXC

Crown 31T-1000

Deka / Duracell SLI31MDC


Not as good value as GC but better than going AGM unless you really need to

[contrail]

Originally Posted by zboss

This is true. We ended up putting our fireflys on their bottom but we could have put them “end up” and expanded our box only a few inches, doubling our capacity. In the end, we are perfectly fine with the price we paid not to have to be concerned with all the issues mentioned in this thread about AGM or FLA.

I don't think you can overstate the tested advantages of the Firefly AGM's with regard to real use scenarios and ability to withstand Partial State of Charge Use. Huge advantage over Lifelines and other batteries. Greater depth of discharge, too, all adding up to the ability to use a smaller bank. "poor man's Lithium battery" they have been called. Zboss, how long have you had yours, and how do you like them.

They have been hard to source, but I found a good supply at Fisheries Supply in the PNW, and mine are on their way. Looking forward to putting them in shortly.

[contrail]

Originally Posted by Chris777

Ok.... More questions. As I have stated above I am limited in my battery compartment to any thing less than 9 3/4" height. I can fit 4, Group 31, AGM or FLA. However I can fit 3 Group 31 FLA @105 amps each and 3 Group 24 FLA @75 amps each. This combo will maximize my batt comp....... BUT is it compatible to have these 6 batts wired in series for a total amp of 540 amp and 12 volt?

If not I will have to go with the Trojan Grp 31 overdrive at 180 amps each..... unless someone has a better idea.

I charge with a 100 amp alternator, 315W solar panel to be instaled shortly and shore power.

Starting battery is totally separate so we are only talking about "house".

36' Sailboat.

Thanks,

Chris

"wired in series"? I think you mean parallel.

[john61ct]

Originally Posted by contrail

I don't think you can overstate the tested advantages of the Firefly AGM's with regard to real use scenarios and ability to withstand Partial State of Charge Use. Huge advantage over Lifelines and other batteries. Greater depth of discharge, too, all adding up to the ability to use a smaller bank. "poor man's Lithium battery" they have been called. Zboss, how long have you had yours, and how do you like them.

They have been hard to source, but I found a good supply at Fisheries Supply in the PNW, and mine are on their way. Looking forward to putting them in shortly.

Yes Firefly Oasis are fantastic, but like LFP do require some good knowledge and gear to care for properly.

And at $500 per 100AH are IMO only justified if PSOC abuse is really unavoidable.

Not for the OP, but in general you could also just buy Duracell GCs at under $100 per 100AH and replace them every 2-3 years, rather than hoping the Firefly's will make it over a decade.

PS best way to source is contact the NA distributor, Bruce @ Ocean Planet and ask which authorized dealer in your region has the shortest waitlist.

When I last checked backorders were 3-5 months.

He is also fantastic for high end solar, helped design Lithionics' LFP systems, a fantastic resource and great guy!

[contrail]

Originally Posted by john61ct

Yes Firefly Oasis are fantastic, but like LFP do require some good knowledge and gear to care for properly.

And at $500 per 100AH are IMO only justified if PSOC abuse is really unavoidable.

Not for the OP, but in general you could also just buy Duracell GCs at under $100 per 100AH and replace them every 2-3 years, rather than hoping the Firefly's will make it over a decade.

PS best way to source is contact the NA distributor, Bruce @ Ocean Planet and ask which authorized dealer in your region has the shortest waitlist.

When I last checked backorders were 3-5 months.

He is also fantastic for high end solar, helped design Lithionics' LFP systems, a fantastic resource and great guy!

Agreed, they are pricey, but I think far more folks are PSOC challenged than realize it, particularly when one factor's in the faster charge acceptance rate of more deeply discharged batteries. I am in that category, having used FLA golf car batteries, both Trojans and, yes, Rolls, for many years.

Bruce is, indeed, a great guy and terrific resource, and he did help me. However, he was as astounded as I was that Fisheries had some, in stock. Ordered mine a couple of weeks ago....should be here in the BVI any day. Took the time to call all the dealers. They had 110 group 21's at the time!