New battery bank size, charging mods... AGM or Carbon Foam

[Good Vibes]

First off thank you all for the help making last season (our first with our 2001 310 #63) a huge success!

We are replacing our current FLA batteries (2xGC2, 1 sealed G31) with AGM mostly due to their age and also due to concerns with off gassing. We do not have shore power but have a 180W rigid solar panel and the stock alternator (50A). Our major drain is the fridge and auto helm as well as charging of ipads etc, All lighting is LED. I'm looking for 100Ah as a budget for weekend and the occasional longer trip. I figure 100Ah is a reasonable guess at our energy budget.

I have read much of the wealth of info available on the forum (again thank you Mainesail and StuJ). We plan to go with 4x GC2 AGM and possibly a reserve if we can fit it in. We are adding a smart(er) charger and an ACR.

If I combine the GC2s into one large series/parallel house bank the capacity should be 440 ah (220 useable). This would be great but I'm not sure I can fit the reserve and worry that I may not have sufficient charge capacity to keep them topped up.

Am I any better off keeping them as 2 separate 220 Ah banks (no reserve) ? Same charging requirements, more switching. What are the thoughts on having two equal sized banks like this? It seems that I would be keeping a lot of our capacity in reserve and drawing down the house bank significantly overnight.

Another thought is to go with 2x Firefly GC31 as a house bank and a single firefly GC31 as a reserve. Still about 230 Ah but able to draw down deeper and the recharging is less critical. I'm not clear if the carbon foam technology has issues still or requires additional mods to the system...

Thanks for any thoughts.

 

[Tom J]

If you go with the two separate 220 Ah banks, you will have a similar setup to the original 4D's that Catalina installed. This will give you a reserve, but involves a lot of switching. The ACR would alleviate some of the switching by first charging the "house" bank, and then automatically charging both banks.
Personally, I prefer a large house bank (4xGC2) and a start (reserve) bank. I located my start battery under the port settee, just ahead of the battery compartment.

 

[leo310]

I currently have 4 Fld GC battery and have been looking at replacements in the next few years. I have talked to a Catalina owner in Vancouver who replaced his Fld batteries with 2 firefly not only did he saved on weight he figures that over time he will save money also.

 

[Maine Sail]

We are replacing our current FLA batteries (2xGC2, 1 sealed G31) with AGM mostly due to their age and also due to concerns with off gassing.

This is a non issue provided you are charging them properly. The idea that AGM's or GEL's can't vent is a fallacy. The ABYC standards, now accepted as Federal Law in Canada, require the exact same venting of AGM, GEL and Flooded batteries. If you want to limit electrolyte use you can install Water Miser Caps on the GC2's.

We do not have shore power but have a 180W rigid solar panel and the stock alternator (50A). Our major drain is the fridge and auto helm as well as charging of ipads etc, All lighting is LED. I'm looking for 100Ah as a budget for weekend and the occasional longer trip. I figure 100Ah is a reasonable guess at our energy budget.

You alternator is a major weak link, especially if considering AGM batteries. If going AGM temp compensation is absolutely critical as burned off electrolyte cannot be replaced.

We plan to go with 4x GC2 AGM and possibly a reserve if we can fit it in. We are adding a smart(er) charger and an ACR.

With AGM's a truly smart charger (temp compensated) and alternator regulator (temp compensated) and good solar controller (temp compensated) are critical. Flooded batteries can take a ton of incorrect charging abuse then just have the electrolyte topped up or the batteries equalized. You can't top up with AGM's and most, other than Lifeline, cannot be equalized. Charging needs to be correct or you can easily burn a large hole in your wallet. Any upgrade to AGM batteries should be treated as a system wide upgrade.

If I combine the GC2s into one large series/parallel house bank the capacity should be 440 ah (220 useable). This would be great but I'm not sure I can fit the reserve and worry that I may not have sufficient charge capacity to keep them topped up.

Unlike flooded batteries the Lifelines use the same plate technology and a G-31 has the same rated cycle life as a GC2 so there is no benefit to using a GC2 Lifeline's over a 12V G-24, 27 or 31. Your 220Ah spec indicates a Lifeline GPL-4CT... The GPL-31XT is a 125 Ah G-31 12V battery which would be a good option in the Lifeline brand and likely afford more space for a reserve bank. Always be sure to only consider AGM batteries specifically built and intended for deep-cycle use. This would include known quality brands such as Lifeline, Northstar TPPL AGM, Odyssey TPPL AGM, Firefly Carbon Foam AGM, Rolls or Full River. It is too early to tell how the Trojan Reliant AGM's will hold up to deep cycle use. I would urge a strong caution on any AGM made by East Penn/Deka for deep cycling use. This would include all the "sticker brands" such as West Marine, NAPA, Sam's Club, Duracell, Mega Crank, Die Hard, Nautilus, Super Start etc. etc. etc.. That said the East Penn GEL batteries are very, very good cycling batteries. However, they require very precise charging so as not to risk over-charging.

Am I any better off keeping them as 2 separate 220 Ah banks (no reserve) ? Same charging requirements, more switching. What are the thoughts on having two equal sized banks like this? It seems that I would be keeping a lot of our capacity in reserve and drawing down the house bank significantly overnight.

One large bank... Why? Multiple House Banks vs. One House Bank

Another thought is to go with 2x Firefly GC31 as a house bank and a single firefly GC31 as a reserve. Still about 230 Ah but able to draw down deeper and the recharging is less critical. I'm not clear if the carbon foam technology has issues still or requires additional mods to the system...

The Firefly batteries are by far the most tolerant AGM to PSoC (partial state of charge cycling) abuse. However like any AGM they must have the correct charging voltages and temp compensated charging. It would be a waste of money to use one as a reserve battery when a cheap East Penn AGM could be charged at the Firefly voltages and would get you buy in a pinch. I would not however suggest an East Penn made AGM for cycling use.

 

[Maine Sail]

The ACR would alleviate some of the switching by first charging the "house" bank, and then automatically charging both banks.

An ACR does not charge either bank "first" or do any priority charging it is simply voltage triggered. The article below goes into great detail on how an ACR actually works. Blue Sea tech support actually sends customers to the article for a better understanding..

Making Sense of Automatic Combining Relays (LINK)


.

 

[SawyerCurt]

I'm sure he'll weigh in when he can, but Jesse wrote up a blog post about his battery upgrade project, and I think he may have discussed why he selected the options he did.

 

[Maine Sail]

I'm sure he'll weigh in when he can, but Jesse wrote up a blog post about his battery upgrade project, and I think he may have discussed why he selected the options he did.

Jesse is now running a LiFePO4 bank. IIRC prior to LFP he was able to fit four GC2's and a cranking battery in the C-310.

 

[SG]

Following on Maine Sail's (and Tom Young's) comments above. If you battery compartment has some reasonable ventilation already; and, you aren't going to be monitoring and upgrading your charging system, then I'd go with Gel Cells.

A quality gel cell will be not that much more expensive than your current set-up. They are more forgiving, out gas (unless over charged) very little. YOU HAVE TO HAVE THEM IN A LOCATION WHERE THEY CAN VENTILATE -- just in case you abuse them and you generate hydrogen gas, as in the Hindenburg.

From m experience, AGM's are not the panacea that you might think. My experience with Lifelines, with a series of quality charging systems and "religious" adherence to procedure went from happy to disappointing to "I had it" over 12 years.

I have a Mastervolt charging system, Balmar Alternator with smart regulator, and Lithium Ion Batteries for my house banks. My two other batteries are AGM Optima start batteries for the generator and main engines.

 

[Maine Sail]

A quality gel cell will be not that much more expensive than your current set-up. They are more forgiving, out gas (unless over charged) very little.

To clarify, GEL's are quite tolerant of PSoC cycling, are valve-regulated, same as an AGM, but do not and will not tolerate over charging. Once you over-charge a GEL battery they go down hill really, really fast. Max charging should be limited to 14.1V to 14.2V and all charge sources temp compensated.. Do this and they can easily last in excess of 10 years (we had a bank last 17 years (max charge rate 14.1V)). Charge them at more than 14.2V and their life can be measured in months.

 

[marchem]

If you go with the two separate 220 Ah banks, you will have a similar setup to the original 4D's that Catalina installed. This will give you a reserve, but involves a lot of switching. The ACR would alleviate some of the switching by first charging the "house" bank, and then automatically charging both banks.
Personally, I prefer a large house bank (4xGC2) and a start (reserve) bank. I located my start battery under the port settee, just ahead of the battery compartment.

Same setup here. Putting reserve in the port settee was easy. We used a battery box for containment, with NRS straps.

 

[marchem]

Jesse is now running a LiFePO4 bank. IIRC prior to LFP he was able to fit four GC2's and a cranking battery in the C-310.

Jesse and others have posted (with pictures) about getting four GC2s and a cranking/reserve battery in the standard battery compartment. I couldn’t figure out how to make that work, plus another issue with doing that is the fore/aft orientation for some of the batteries ends up being non-optimal (Installation & Orientation of Flooded Batteries on Boats), at least for flooded cells.

 

[JRT]

@Good Vibes this is the thread on my 310 from the previous owner and I'm very happy with the setup and battery installation location. My 31o has the wood trim that was added to the top for the extra ruffle around the cushions and is removable to completely access all the batteries.

Battery Charger question...

If that location works I could use #6 according to the chart. How much heat would it add to the aft berth? We only use it for storage.

forums.sailboatowners.com

 

[Good Vibes]

Thank you all for the detailed replies. Ill need to spend some time digesting. I had been leaning to the Carbon foam as a bit of a simple fix but will take some time to really think it through. We were looking at Rolls AGMs or FLA if we decide to go the route. Our charging is limited to our Solar panels since we only use the engine fo two or three hours a day when out. less if the wind is doing what it should.

I have to learn about temp compensated charging. This is the first I have read about it.

Our concern with off gassing stems from our existing set up which is constantly setting off our CO detectors on hot days when we aren't at the boat. The 2xFLA GC2s are 5 yrs old.

Thank you again for all the input.

 

[Maine Sail]

Our concern with off gassing stems from our existing set up which is constantly setting off our CO detectors on hot days when we aren't at the boat. The 2xFLA GC2s are 5 yrs old.

If they are doing this, something is wrong with the PV controller or the batteries. What model PV controller..?

 

[Good Vibes]

If they are doing this, something is wrong with the PV controller or the batteries. What model PV controller..?

Thanks for the reply. Its an Enerwatt EWC30. Ive attached a pic of the spare the PO included.

 

[Good Vibes]

I thought I would help clarify the discussion with a picture of the existing installation. Note the orientation of the GC2s is in the wrong direction and the group 31 is maintenance free vice FLA. The red GC2s are forward port side.

 

[CYQK]

Getting ready to set up new batt boxes and want to install a vent system,there was not one previosly installed
Where did you and how did you vent your boxes? Do you vent overboard?

 

[Good Vibes]

This is a non issue provided you are charging them properly. The idea that AGM's or GEL's can't vent is a fallacy. The ABYC standards, now accepted as Federal Law in Canada, require the exact same venting of AGM, GEL and Flooded batteries. If you want to limit electrolyte use you can install Water Miser Caps on the GC2's.



You alternator is a major weak link, especially if considering AGM batteries. If going AGM temp compensation is absolutely critical as burned off electrolyte cannot be replaced.



With AGM's a truly smart charger (temp compensated) and alternator regulator (temp compensated) and good solar controller (temp compensated) are critical. Flooded batteries can take a ton of incorrect charging abuse then just have the electrolyte topped up or the batteries equalized. You can't top up with AGM's and most, other than Lifeline, cannot be equalized. Charging needs to be correct or you can easily burn a large hole in your wallet. Any upgrade to AGM batteries should be treated as a system wide upgrade.



Unlike flooded batteries the Lifelines use the same plate technology and a G-31 has the same rated cycle life as a GC2 so there is no benefit to using a GC2 Lifeline's over a 12V G-24, 27 or 31. Your 220Ah spec indicates a Lifeline GPL-4CT... The GPL-31XT is a 125 Ah G-31 12V battery which would be a good option in the Lifeline brand and likely afford more space for a reserve bank. Always be sure to only consider AGM batteries specifically built and intended for deep-cycle use. This would include known quality brands such as Lifeline, Northstar TPPL AGM, Odyssey TPPL AGM, Firefly Carbon Foam AGM, Rolls or Full River. It is too early to tell how the Trojan Reliant AGM's will hold up to deep cycle use. I would urge a strong caution on any AGM made by East Penn/Deka for deep cycling use. This would include all the "sticker brands" such as West Marine, NAPA, Sam's Club, Duracell, Mega Crank, Die Hard, Nautilus, Super Start etc. etc. etc.. That said the East Penn GEL batteries are very, very good cycling batteries. However, they require very precise charging so as not to risk over-charging.



One large bank... Why? Multiple House Banks vs. One House Bank



The Firefly batteries are by far the most tolerant AGM to PSoC (partial state of charge cycling) abuse. However like any AGM they must have the correct charging voltages and temp compensated charging. It would be a waste of money to use one as a reserve battery when a cheap East Penn AGM could be charged at the Firefly voltages and would get you buy in a pinch. I would not however suggest an East Penn made AGM for cycling use.

Thank you again for the in depth response. I just got off the phone with the battery salesman who was quick to point out that the both switch needed to be disconnected if I mixed fireflies with another AGM. True? He is trying to sell me another firefly battery so I am a bit suspect...

 

[Maine Sail]

Thank you again for the in depth response. I just got off the phone with the battery salesman who was quick to point out that the both switch needed to be disconnected if I mixed fireflies with another AGM. True? He is trying to sell me another firefly battery so I am a bit suspect...

Who is this "battery salesman"?

Firefly's charge at 14.4V absorption (no higher and always temp compensated) and 13.2V - 13.4V float. An East Penn AGM can also be charged at these same voltages. While 14.4V is slightly less than optimal for a cycled East Penn AGM, that battery would not be being cycled so 14.4V and 13.2-13.4V would be fine. You DO NOT need to waste money on a Firefly AGM so that it can sit there as a $550.00 piece of ballast.

I do not however recommend using the BOTH switch for charge directing. Too much room for error and a simple 7610SI ACR would be a much safer approach. Feed all charging to the house bank (temp compensated) and use the ACR to charge the start bank..

 

[Good Vibes]

Ahhh no names, no pack drill... But thank you for the quick response. I think he was well intentioned and thinking about drawing off both types in the BOTH position. Your answer makes great sense...(no surprise) Thanks again for the help.