This shall be the third and last post on Redemption’s electrical bits as it has come, as all things do, to an end. If you haven’t been keeping up with this electrifying trilogy, you can see the previous two here and here. Well we left off the last one with the boat being completely rewired from all accessories to cabinet and cabinet to switch panel, new items were installed or old items were cleaned and reused. Let’s dive right in and see just what else has been done since!
From the beginning in Vol. 1, we said we were going to be installing some second hand, ex-EV(electric vehicle) CALB SE 180ah lithium iron phosphate batteries instead of the typical lead acid variety. We have shaved weight(only ~150lbs now), increased both usable and total amphour capacity, and decreased charge time due to higher acceptance rate from charge sources. Once we dove fully into this there was no turning back, it had to work! I won’t get into the overly technical aspects of these batteries as this isn’t really about that, what I can tell you is how I am using them and protecting them.
The cells need a box or rack of some sort to not only keep them together when in the boat but also to keep them in compression as lithium cells can expand if abused. Keeping them in compression can save a cell if it gets abused briefly, think over charge. I set off making a rack for them. I placed the batteries on the ground in the order they would be in the boat, 3P4S(3 parallel 4 series). This give me three 180ah 3.34v batteries in parallel which gives me 540ah cell. Put those four cells of 540ah 3.34v in series, connecting them from + to – making sure to cross the entire cell(think diagonally), to give me a battery pack of 540ah of 13.36v. When they were in a pack I made my measurements and cut 3/16″ aluminium plate I had left over from my fuel tanks(LINK) and some 1/2″ aluminum square tubing to size. I bought some 1/4 20 all-thread to go inside the tubing to connect the two plates together and compress the pack. Welded some angle to the bottom of the plate to allow me to secure the pack to the boat with 8 large screws. I had a piece of 3/8″ Plexiglas laying around so I made a cover with that and some Al angle to fasten to the rack. When it was all finished and fit nicely, I gave the Al bits a little paint to dress them up a little and give a level of protection to keep it from future oxidizing.
Once the rack was complete, it was time to prep the boat where the batteries would be going. I decided to put the batteries in the port aft stateroom under the bunk. This was the best place we could put a pack that size without putting them in the engine compartment, which wasn’t an option really as the heat kills all batteries. Luckily, there was JUST enough room between the foot of the bunk and the water tank to fit everything. I first sanded the compartment down to give it a good cleaning. Then we needed to add a brace to keep the plywood from bowing over time due to the weight of the batteries. Got some resin mixed with bubbles and short hair I stuck a piece of treated 2×6 I had cut down to fit. When that was all finished and the board fit, everything got a fresh coat of white epoxy paint, because everything always looks more professional with fresh paint! I dry fitted the rack in the compartment to double check that it fit, all good thank goodness.
Next, it was time to run the 1/0 main cables that run from the compartment to the panel. Before I ran the cable I twisted them on the dock. My theory for this was to reduce RF noise, I have read online that this can help so it was worth a try. Put some chafe sleeve on a the portion that goes from the batteries, through the engine space, under the starboard bunk where the sea strainer is and then up the side of the hull to join the rest of the wires. This took finagling, modification, contorting, and I think some skin when pulling these large cables around the boat. BUT it’s done! I ordered my cables from genuinedealz where you can order made to size, already crimped and heat shrink’ed.
From here it was time to bring the batteries to the boat for final resting. Between Michelle and I, it was a long job. From the garage to the truck, truck to the dock slip(which is down the dock away from the truck 50 yards), dock to on the boat, the cockpit to the galley counter, and then finally I started putting the cells inside the rack which was inside the compartment. Granted they aren’t that heavy (~12 lbs) but there was twelve of them so at best you could only take two when walking and then handing them over one at a time, took some trips needless to say. All inside the rack, I tightened everything down and began to put the cells back in connection with one another and put the individual cell boards on. These monitor cell level(the three cells in parallel) voltage to make sure they are not wandering around too high or low from the rest or from a high or low voltage situation.
With the easy stuff over, it was now time to wire up the BMS(battery management system), buses, contactor, and fuses to everything.Now this is where I had to change plans about three times before I finally figured out how it was going to be done. I drew up diagrams of how things would be laid out before, got to the boat, wasn’t going to work. Start over. Fail. Try one more time. Got it? Maybe. I ended up finally settling on a layout that would work for me and the compartment. I had to make a new shelf to the right of the pack to hold all of these components down because there wasn’t enough room once the batteries were in place. The left side is where the BMS and Balmar alternator regulator is mounted. I started to wire up the pack to the components, mounted the new Victron Phoenix 30amp-12v battery charger in the back of the lazarette away from the engine and hatches so it should be okay. We didn’t need a big charger because I figured if I’m at the dock I’ll be there long enough to charge the batteries up and if I’m at anchor a big charger won’t do us any good without a genset. We will primary use the alternator to charge when away from the dock until we get some solar to supplement.
While running various wires, we installed the Victron BMV-702 to monitor amphours going in and out of the battery. These neat little gadgets allow us to know exactly when to charge and when we are all topped up on electrons.
They do require a good setup and need routine checks and calibration to make sure they are calculating correctly. All that is needed to wire this thing up was to run the provided CAT-5 cable to the shunt which has its own little circuit board attached. A small sense wire is ran from the battery + (I ran it to the battery side of the contactor that way its always on). That’s it! I wish everything was that plug and play.
I had to make up some brass connector bars from some stock we had laying around because using 1/0 wire plus lugs to go a few inches wasn’t going to work. Each bar was a custom fit and each had different hole diameter and spacing. Once fit, the bars were polished to a high shine and a fitted with a piece of adhesive heat shrink in the middle.Everything was hooking up nicely and started to look great at this point. House panel, battery charger, and alternator wires were connected to their respective ANL fuses to protect the wires in case of a short somewhere. We have two common bus bars from the main, one for charge sources and the other for load sources. The charge sources will be from the alternator, shore battery charger, and future solar controllers. The load will include the house panel, the starter, and the bilge pumps. This makes it easy to not only keep wires separated but to keep from having more than one or two wire lugs on one bus bar bolt.
When the right side of the pack was just about as complete as it could be, I started on the BMS box. I had been working on this box at home at night for some time. It was now time to hook everything up where it needed to go so the BMS could do its thing. I have a main On/Off switch with a blue LED light to turn on the entire system. When that is flipped on, the board comes to life, a red LED status light comes on, the main contactor clicks close and now there is power to the main bus. There is a small piezo horn on the box to alarm in the event we have a problem with the cells or pack, to which the red light will flash a certain sequence to let you know whats going on. There is also a momentary On/Off switch to reset the board when you acknowledge the alarm. The board will also shutoff the charge sources if the voltage of the pack or a cell gets too high, say if a regulator or solar controller goes bad and starts charging at a higher voltage than previously set. Also, any of the loads pull the voltage down too far it can close a relay to shut off the load bus. (NOTE: I do not have this installed to date) Lastly, if something happens where the charge or load sources are not cut off, the board will open the main contactor and shut the whole pack off from everything. Think of that as the final emergency shutoff. And that ladies and gents, is what the BMS box does in a nut shell.
Knowing I was going to need a way to isolate the house panel and starter from the load buses, I made a bracket out of some spare Al plate and installed two Blue Sea On/Off battery switches. One will be for the house panel, the other to shut off the starter on the engine. As it goes: load bus > fuse > On/Off switch > to panel/starter. This panel goes just next to the left of the pack but inside the two doors at the foot of the bed. This way we don’t have to lift up the mattress and board to turn these on or off, easy access.
With everything hooked up in the battery compartment, it was time to turn on the BMS. If you asked Michelle about my reluctance to flip that little switch she would tell you the look on my face when that little blue light came on and that contactor gave out a loud “click”. I was so overwhelmingly joyful, I just started smiling and was just so stinking happy it. Also, there was no smoke or sizzling and I was getting 13.36v at the main bus! I turned on the house panel switch and rushed to the panel to see if I was getting voltage… 13.36v!! AWESOME! What a relief! I have been poring time and energy into researching, building, and planning this entire system for months and it all came to a magnificent end.