I replaced the two, 65 pound each, 235 ah 6 volt lead acid batteries that were bought in 2021 by the former owner with two, 22 lb each 100 ah mini lithium batteries. Lithium batteries should give me 10 times the life of the lead acid batteries – which lived right up to their 5 year house battery life I found online. Much more useful power. And so much lighter.
I bought the batteries from Renogy and had them shipped to Lynden Transport in Seattle to come up on the barge. I note the shipping would have been $176 if the batteries were sent by Renogy in the same shipment, but they were not. The batteries arrived on separate days so I was charged $176 for the first and $85 for the second because, as the agent told me, Lynden does not consolidate shipments that arrive there. When I asked Renogy why they didn’t ship the batteries together as one piece, since that’s how I bought them, they said they could not do that due to hazardous material regulations. Tuition paid. Lessons learned.
I found Blue Marine, a Seattle business that seemed expert in lithium battery systems, online, and emailed to ask them what I would need to change from my old lead acid batteries to lithium batteries. I described my current system and said I mainly wanted to be able run my little 5 cu ft AC freezer overnight during the summer, as the lead acid batteries were at the end of their useful life and weren’t doing it anymore. I thought a 200 ah single lithium ion battery would work. They advised me to get two, 100 ah batteries instead – sort of for “backups to backups” system, which is my style. I’d written to them and didn’t hear back for a day or two, so continued searching for batteries when I found the Renogy mini batteries. Wow. 100 Ah each and so small. There were lots of cheaper batteries imported from overseas, but Renogy was a Canadian company with a US office, and I liked that. I found out at check out that the batteries were also on sale, so even better. I ordered two of the batteries. I then got a lengthy, detailed explanation and advice on the system I needed from Blue Marine.
I really appreciated their great information in layman’s terms, so I ordered the rest of the pieces they said I’d need to put the system together. For charging the battery bank – two 100 Ah lithium batteries connected in parallel for the boat’s 12 V system (the 6 V batteries were connected in series) – I’d need a DC-DC charger. This was because unlike conventional batteries, the lithium batteries would call for a lot of juice from the 80 amp boat alternator and likely overheat it. The charger meters the charge into the lithium batteries at a proper rate via the starting battery. Hooking up the wiring for the charger was the biggest chore. The 4 AGW wires were very difficult to get rounded to size to go into the little square compression clamp fittings of the charger. Two wires from the starting battery being charged by the alternator go into the charger, along with two wires going to the battery bank. I got three wire in tight, but one just would not hold and repeatedly fell out. So, I took a 4 AGW ring terminal, crushed the eye together by squeezing the sides of it with vice grips so it would fit in the square socket in the charger, then soldered the end of the wire into the other end of the ring terminal. That’s one part of the system I don’t like. The wiring sockets are right next to each other. You wind the stripped wiring as best you can and jam it into the socket and screw it down as tight as you dare. The + and – are adjacent to each other, and I worried a spark could jump across the bare wire that is slightly below each socket after you screw it it. I tried to make sure there were no stray strands sticking out, and used some heat shrink wrap up to where the wire insulation meets the exposed wire to make is safe as I could. I’d much prefer a ring terminal for a safer, more secure fit. These chargers would not take a 2 AGW or larger wire. 4 AGW wire was definitely the max.
I was a bit confused by the directions for the smart shunt gauge, but finally found it was simple after seeing an explanation on some facebook group: all your negative connections to the battery go to one side, and the other side has a single wire from it to the negative on the battery bank. It’s so simple, it sounded complicated. It’s like a single negative post that’s remote from the battery, except it has two posts instead of one, with a bar in between. The shunt is for monitoring the battery health. I’m not sure how useful I’ll find it over the battery meter on my plotter or battery guage on the electric panel, but Blue Marine said I should have it, so I got it.
There is a concern about fires with lithium batteries, and that was where the massive T fuses come in. I put one of these on each of the positive leads of the two batteries. From what I’ve read, traditional fuses blown in a lithium system can get so hot they actually fuse back together, and now you’ve got current and heat flowing unchecked and a fire can start. These fuses are made so they can’t melt back together.
There was lots of room now in the battery box due to the smaller batteries. I actually could have fit 3 of these 100 Ah batteries in there and that would have made for a nice tight fit. I considered lots of options for securing the batteries in place. I had a couple expired survival suits I got from Bear for some projects. I’d used a piece of another one to cover my anchor capstan on the bow, but realized after a few seasons that the closed cell neoprene was subject to fairly quick deterioration from sun/UV light, so I ended up not using the suit material for that. I cut off the arms and a leg of the suit. I rolled each piece up tight, and jammed them between the batteries and between the sides of the batteries and the battery box. That stuck the batteries in place well, and it will be easy to remove the neoprene rolls should I need to do anything with the batteries. I also found that closed cell neoprene is a very “non-flammable” material, which also made them a good choice. There is lots of air circulation between the batteries and the rolled neoprene and battery box, so I’m not worried about the neoprene material keeping heat in the battery box.
I tackled the job over several days. If I got tired or hungry or under caffeinated, I quit for the day. It’s alot easier not to be in a rush nowadays. This is the kind of job you don’t want to rush. I’ll be excited to see how it performs during deer season.
Now to tackle the pesky leak in my skiff. I took the skiff for a test ride with the new fuel tank and when I returned and pulled the plug, a significant amount of water drained out for the short run. I have a leak somewhere, but cannot find it with the naked eye. I parked the skiff on its trailer in the driveway on levelish ground and filled the inside of the hull with water from the garden hose. I checked awhile later and the hull below decks was nearly full. And not leaks. Except for the drip at the drain plug. What a relief. No patching or welding needed. Just need to coat the threaded plug with pipe dope each time I put it in for now. End of boat chores for now.