dhays
Guru
- Joined
- May 26, 2015
- Messages
- 9,045
- Location
- United States
- Vessel Name
- Kinship
- Vessel Make
- North Pacific 43
I have known this was coming, but the time is now. My almost 7 year old house bank with 3 Chinese made sealed LA 8D batteries is dying. I need to replace it and am trying to come up with options. I am hoping that you all can help me walk through the decision process.
I have a MagnaSine 2812 inverter charger and a 6KW genset. No solar at this time. The other batteries in the boat are an 8D AGM start battery of undetermined age, 2 original 8D sealed LA batteries for the thrusters, windlass, and crane, and a group 27 AGM genset start battery that is a year old.
The batteries are in the aft lazarette underneath the cockpit. They are not easily accessible with very little overhead clearance. In this same space are the thruster batteries, DC electrical panel, and a diesel hydronic furnace. I can changed the form factor of the batteries if needed.
I would prefer to not go with the 8D size again. They are simply hard to manage. However, I certainly can if that is going to be the best option. Watering batteries in this location will be tough. However, I could opt for a watering system if I went with wet LA batteries. I would prefer to spend as little money as possible (I am a sailor after all) but at the same time am looking at long term cost per kWh.
Here are the options as I see them. I am also open to others I haven't thought of.
Wet GC2 batteries - I can buy these at Costco for under $80 each with each pair giving me 210 AH. I could fit 8 to 10 where those three 8D batteries are now by changing the battery boxes. A watering system would keep them watered. It would take a bunch of cables but I figure for under 1 boat unit I could install everything. This would give me 800-1000AH of capacity, 1/2 of which would be usable so 400-500AH.
8D AGM - Other than the 160lbs each, this would be the simplest and easiest to do as three would drop in to replace what I have. More expensive at ~$1,800 for three of them. 700-750AH with about 350-375AH usable.
Firefly Oasis: I would prefer to be looking at this in a couple years instead of now. I'd like to have other folks get more experience with them. $500 each for 116AH. Can be discharged down to 20% SOC apparently, but doing that dramatically reduces the number of life cycles. They claim a 50% depth of discharge will give 3600 cycles, 80% will give 1000. That is still about 2x the number of cycles a wet cell GC2 would have at 50%.
I'm sure there are other options as well. I'm not interested in LiPo batteries at this point and I know there are other form factors which would be good to look at. AGM GC2?
For the way we currently use the boat most of the time, the Oasys is likely overkill. We primarily weekend the boat with an occasional week or two away from dock power. GC2 wet cells would be fine for us but I have an ignorant question. What risk is there to have the wet cells in the same space as the diesel furnace? What is the realistic risk of an explosion due to gas buildup in the same space as a flame?
I have a MagnaSine 2812 inverter charger and a 6KW genset. No solar at this time. The other batteries in the boat are an 8D AGM start battery of undetermined age, 2 original 8D sealed LA batteries for the thrusters, windlass, and crane, and a group 27 AGM genset start battery that is a year old.
The batteries are in the aft lazarette underneath the cockpit. They are not easily accessible with very little overhead clearance. In this same space are the thruster batteries, DC electrical panel, and a diesel hydronic furnace. I can changed the form factor of the batteries if needed.
I would prefer to not go with the 8D size again. They are simply hard to manage. However, I certainly can if that is going to be the best option. Watering batteries in this location will be tough. However, I could opt for a watering system if I went with wet LA batteries. I would prefer to spend as little money as possible (I am a sailor after all) but at the same time am looking at long term cost per kWh.
Here are the options as I see them. I am also open to others I haven't thought of.
Wet GC2 batteries - I can buy these at Costco for under $80 each with each pair giving me 210 AH. I could fit 8 to 10 where those three 8D batteries are now by changing the battery boxes. A watering system would keep them watered. It would take a bunch of cables but I figure for under 1 boat unit I could install everything. This would give me 800-1000AH of capacity, 1/2 of which would be usable so 400-500AH.
8D AGM - Other than the 160lbs each, this would be the simplest and easiest to do as three would drop in to replace what I have. More expensive at ~$1,800 for three of them. 700-750AH with about 350-375AH usable.
Firefly Oasis: I would prefer to be looking at this in a couple years instead of now. I'd like to have other folks get more experience with them. $500 each for 116AH. Can be discharged down to 20% SOC apparently, but doing that dramatically reduces the number of life cycles. They claim a 50% depth of discharge will give 3600 cycles, 80% will give 1000. That is still about 2x the number of cycles a wet cell GC2 would have at 50%.
I'm sure there are other options as well. I'm not interested in LiPo batteries at this point and I know there are other form factors which would be good to look at. AGM GC2?
For the way we currently use the boat most of the time, the Oasys is likely overkill. We primarily weekend the boat with an occasional week or two away from dock power. GC2 wet cells would be fine for us but I have an ignorant question. What risk is there to have the wet cells in the same space as the diesel furnace? What is the realistic risk of an explosion due to gas buildup in the same space as a flame?