Oasis Firefly vs Victron SuperCycle AGM batteries

[mpstan]

Our new to us OA 42 came with 6 serviceable lead acid Trojans which are 7 years old. We planned on upgrading next year, but our 29 year old Trace inverter has died so we are planning our electronics upgrade now.

We have an authorized Victron distributor out here near Bellingham WA, and our electrician likes and is comfortable with Victron products, so that's what I would like to go with for an inverter.

Based on space constraints I am thinking a Vicron Multiplus 3000 12v makes the most sense. If it is possible I'd like to have a dedicated charger for the starting batteries and a second for the genset battery, and if feasible direct the engine alternators to charge the house bank.

Would love input from anyone who has experience with both Firefly carbon foam batteries as well as the Victron Super Cycle AGMs. For me it appears that arranging two sets of Fireflys, with each set consisting of 3 4v batteries, would yield 900 AH for about $4700; going with 6 12v Supercycles, 170AH each, I'm looking at 1020 AH bank for $2820. That's cheaper than even going with Trojan Golf Cart AGMs rated at 1080 AH although with a potentially shorter cycle life.

If I have this right, I'm thinking Victron batteries might be the way to go, but comparing life cycles for these two batteries is not easy. would love to hear other's insights.

 

[Comodave]

I am installing a new house bank made up of LiFePo4 batteries. They are great in a deep cycle bank. I went with Lion Energy batteries. They come with a lifetime warranty and are rated for 3500+ cycles to 0% but is better to stick to 20% SOC. They weigh 23 pounds each. They aren’t cheap but did I mention they have a lifetime warranty.

 

[Gordon J]

I installed fireflies 18 months ago. I combined engine start bank with house bank. I think the total is rated at 932 amp hours. I have two generators, each with its own start battery. I disabled the internal voltage regulators on my twin Cummins 330hp engines and installed two Balmar regulators controlled by a Balmar center fielder, which coordinates output of both alternators.

I chose fireflies because they offer near lithium performance, but are rugged enough to live in the engine room. Think high temps.

As an aside, this past summer, the power pedestal went out and my batteries were totally drained. I was able to bring them back to 100 percent as advertised. I think it was money well spent.

I am guessing these are the last batteries I will buy, other than for the generators.

Gordon

 

[rslifkin]

On the charger front, if you want to simplify a bit, ditch the generator start battery. Keep the separate engine start batteries, but just give the generator a 1-2-both-off switch to allow it to start from either engine battery. It's a smaller load than starting an engine, so plenty of power available. And 1 less battery to maintain (and have to charge) with accordingly less weight and space usage too.

Personally, when I re-did my setup, I went to 3 battery banks. Start 1, Start 2, House. Each engine gets its own battery, generator normally runs from Start 2. Either engine or the gen can use either of the start batteries though.

For house charging underway, each engine alternator feeds to its start bank (start power is safety critical IMO) and then has an ignition-interlocked ACR to the house bank. So once each engine is running, voltage on the start battery comes up (alternator online) and then a couple second delay, the ACR for that engine engages and feeds power to the house bank.

On shutdown, the ACRs are disabled as soon as each engine's key is turned off (so the ACRs are out of the picture for shore or generator charging). So far, that setup has worked perfectly. Easy to confirm all is working as well. Watch each engine's volt meter at startup and you see it climb as the alternator brings voltage up, then a downward twitch as the ACR engages. If you see that happen on both engines, then you know both alternators and ACRs are working.

 

[Pau Hana]

I considered Firefly batteries, but decided to go the lithium route, in conjunction with Victron for the charging/inverting duties and management, Lee-Niceville alternators, and Wakespeed for alternator control.

I’m also combining the start batteries into 1 8D from 3.

Fun stuff- writeup to come as soon as complete...

 

[rgano]

If you have a depleted house battery bank with ARC connection to a relatively better charged start bank, what happens when the alternator connected to the start side begins to charge? The voltage at the ACR is going to very quickly be at the "combine" threshold. Then there is a surge of current to the "thirsty" house bank and a possible consequent lowering of the voltage at the ACR to the low-voltage open value. It seems that this could cycle the ACR for a while until things get sorted out. OTOH, if the alternator output goes to the house bank, the possibility of such cycling is eliminated. Anyway, the argument always seemed to make sense to me.

 

[rslifkin]

If you have a depleted house battery bank with ARC connection to a relatively better charged start bank, what happens when the alternator connected to the start side begins to charge? The voltage at the ACR is going to very quickly be at the "combine" threshold. Then there is a surge of current to the "thirsty" house bank and a possible consequent lowering of the voltage at the ACR to the low-voltage open value. It seems that this could cycle the ACR for a while until things get sorted out. OTOH, if the alternator output goes to the house bank, the possibility of such cycling is eliminated. Anyway, the argument always seemed to make sense to me.

I did have that concern when I first put the setup together, although there's a delay on engage and disengage to avoid it cycling too quickly. I've yet to actually experience the issue though, even with the house bank around 60% and using the windlass to pull in the anchor.

In my case, my engines need power to run, so if I wired it the other way, I'd be slowly depleting the start batteries until the house bank came up enough for the ACRs to engage. I'd rather have them cycle a few times and have slower initial house charging than draw down the start batteries.

 

[ksanders]

I recently completed a dual Victron installation using parallel Multiplus 12-3000 units, a BMV 712 battery monitor and a CERBO GX with touch screen.

I did not replace my FLA house bank as it is only 1 season old and is properly sized.

I cannot be happier with the installation. It maximizes my charge current when on generator and reduces output when the main engine alternator is operating as to not over current the batteries. When In port I reduce the AC input limit from the touch screen to match whatever shore power is available.

Even though I am now maximizing my 200 amps of battery charge current capability, with any FLA bank you are essentially operating in the 50-80% SOC range when on the hook. The beauty of the newer battery technologies seems to be the ability to maintain high charge currents to near 100% capacity, which would reduce generator run time when on the hook. The mitigation factor to that is on days when you are underway your batteries will get 100% charged anyway.

 

[Insequent]

I installed 10 x 170Ah Victron SuperCycle for house bank in early Sep. Happy so far but obviously very early days.

Firefly aren't available here, so were not an option. I chose the SuperCycle versus normal AGM due to the claim by Victron that they can tolerate full discharge. Now that is not something I plan to do, but it can happen due to power outage at my marina and a quirk in my reverse polarity device.

 

[rgano]

I did have that concern when I first put the setup together, although there's a delay on engage and disengage to avoid it cycling too quickly. I've yet to actually experience the issue though, even with the house bank around 60% and using the windlass to pull in the anchor.

In my case, my engines need power to run, so if I wired it the other way, I'd be slowly depleting the start batteries until the house bank came up enough for the ACRs to engage. I'd rather have them cycle a few times and have slower initial house charging than draw down the start batteries.

Fair enough. My engine has nada electrical needs outside of the alarms once started. There used to be a massive draw by the two air heater coils in the air box at startup, but they are gone now. I am guessing that unless the alternator is undersized or house outsized that the ACR closed voltage would not take long to be reached; so it the real world, maybe it makes little difference which way we hook these things up. Interesting to consider though.

 

[mpstan]

At the end of the day, my mechanic recommended AGM Lifelines, so we now have 1200 AH new AGM house bank, Victron 3000 Multiplus, and 2 Gr31 AGM starting batteries. I have a finicky 8KW Westerbeke to charge. We are still researching alternators which will be regulated by Wakespeeds.... we are not seeing any well established upgrade options beyond 105A Leece Nevilles for 3208 CATs. . Thanks everyone

 

[DavidM]

I am a little surprised that everyone on this thread has installed super premium Firefly, Victron and Lifeline batteries. Well I guess a comparison of super premium batteries was the premise of the OP. Sure those are very good batteries although I have some doubts about the first two until we get some real, long term feedback.

OTOH, I decided to go in an entirely different direction. I installed two very cheap WindyNation 106 Ah AGMs for $180 each. Those were the cheapest semi name brand AGMs I could find. I went with these mostly due to price, but also with the expectation that I could occasionally discharge them to 20% of SOC without too much harm.

Time will tell.

David

 

[Pau Hana]

I am a little surprised that everyone on this thread has installed super premium Firefly, Victron and Lifeline batteries. Well I guess a comparison of super premium batteries was the premise of the OP. Sure those are very good batteries although I have some doubts about the first two until we get some real, long term feedback.

OTOH, I decided to go in an entirely different direction. I installed two very cheap WindyNation 106 Ah AGMs for $180 each. Those were the cheapest semi name brand AGMs I could find. I went with these mostly due to price, but also with the expectation that I could occasionally discharge them to 20% of SOC without too much harm.

Time will tell.

David

Cheap is ok on the purchase side: the known quality of the premium brands suggest that there is a reason for the higher price.

Personally, I want to not worry about the battery bank on the hook- and don’t get a warm and fuzzy from off brands.

 

[rsn48]

I am a little surprised that everyone on this thread has installed super premium Firefly, Victron and Lifeline batteries. Well I guess a comparison of super premium batteries was the premise of the OP. Sure those are very good batteries although I have some doubts about the first two until we get some real, long term feedback.

So I will link to a discussion in the cruising forum. The title of the thread is: "I tried to murder my fireflies." This guy is one of those early in types. He has a beautiful classic lines sailboat. He bought Efoy fuel cell as he didn't want to wreck the visual lines of his boat by installing solar panels. In the thread I like to he discusses his use of fireflies with Efoy.

https://www.cruisersforum.com/forums/f14/my-attempt-to-murder-my-firefly-batteries-221607.html

I edited this in, I noticed the first reponse to his opening post challenges the voltage drop saying fireflies loose juice just like any battery. They do not. Fireflies are the closest non-lithium battery to lithiums, the only one big negative is their weight which is like an AGM not like lithium. Fireflies lose 1 % of juice per month, FLA's 15% per month, Lithium's 1 % a month.

 

[Bacchus]

I am not familiar with Windy Nation that David mentioned but East Penn, maker of Duracell and many other branded battys sells AGMs at about the price David listed.
I have had good experience with them, will continue to use them and believe they represent a very good value. These less expensive ones may not provide equivalent output or total AHs over their life as the more expensive ones but I think on a $/Total AH basis they are a better buy.

 

[ksanders]

Cheap is ok on the purchase side: the known quality of the premium brands suggest that there is a reason for the higher price.

Personally, I want to not worry about the battery bank on the hook- and don’t get a warm and fuzzy from off brands.

I suppose budgets are budgets.

If someone were re-doing their charging system I would rather see them (if need be) buy premium high capacity inverter/chargers and the appropriate sized wiring and cheapo batteries with the idea that in a season or two they can drop in a set of premium capability batteries.

I took the route of keeping my 840AH FLA bank since it was a this season purchase, and upgrade the charging system with stacked Victron units.

That way I received a huge benefit of faster recharge times (almost half in real use), with the knowledge that if I want to further enhance my system all it will take is a battery purchase.