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We were hanging in Annapolis on a June evening when Brian offered us Delos’s couple year old lithium bank. My immediate response was that I would have to think it over. The conversion process seemed like such a daunting project to take on and there really wasn’t anything wrong with our current bank of AGM’s. After a night of sleeping on it I came to my senses and said “Hell Yea we will take em!”. Our AGM’s were about five years old and would likely need replacement in a few years. We decided to take the money that we would have spent on a new bank and use that to complete the conversion process. With the decision made I got down to researching what would be required to successfully convert our electrical system.
We are installed Battle Born (Labeled Transporter Energy which is the UK Distributer) lithium iron phosphate batteries. These batteries come with a built in B.M.S (Battery Management System) that protects the battery from high/low discharge, high/low temperature compensation as well as short circuit protection. Lithium batteries have many benefits over traditional lead acid batteries including much faster charging times, reduced weight, and ability to be fully discharged. The result is a battery that is 2-3 times more energy dense, and charges 5 times faster than a traditional lead acid of the same physical size. We are able to fit six, hundred amp batteries in our battery box.
Where to start? Our lithium batteries are advertised as “drop in” but what does that really mean? What systems could reprogramed and what do we need to replace? We are hoping to use as much of our old gear as possible to keep the conversion on budget.
Lithium batteries a rest at a higher voltage than traditional lead acid batteries. A fully charged lithium battery rests at about 13.4v and by time the battery voltage is at 12.8v it only has 17% capacity left. This is very different than a lead acid which will rest at about 12.8v when full. This voltage difference makes proper programming of charge sources very important.
Calico Skies is charged by several means; we have solar panels, a wind generator, a/c battery charger as well as the alternator on the main diesel. All these sources combine to keep the battery bank topped up in a variety of conditions as well as provide redundancy in the event of failure of a charge source.
Solar/Wind
Programming the solar and wind controllers was pretty straight forward. Our wind generator has a bluetooth interface easily allowing changes to the charge voltages (Bulk/Absorption 14.4v Float 13.5v). Our solar controllers needed upgrading to newer units as I wasn’t happy with the performance of our Gensun controllers. I think the main issue is that we wired our solar panels in parallel, with a controller for each panel. I did a little research and the charge controllers don’t kick in until the panels voltage is roughly 5v higher than the batteries. This was causing the controllers to prematurely end charge despite the batteries not being fully charged. We wired our solar panels in series for the panels in like shading. Our new controllers are from Victron energy.
Victron Charge Controllers:
50 Amp https://amzn.to/3orkL8w
30 Amp https://amzn.to/3frb4Ty
Alternator
Calico Skies has a newer Balmar 6 series 80 amp alternator. We had the alternator paired to a AR-5 external regulator but opted to replace the AR5 with a new Lithium specific regulator the MC614. We were able to program this regulator to the proper voltages, in addition we added an alternator temperature sensor which is very important as lithium batteries have the ability to accept a tremendous amount of power which can cause alternator overheating or failure. Through trial and error we determined that we had to reduce the alternators power from 80 amps to 55amps to avoid triggering the regulators overheating protection.
The other piece of gear we added to protect the alternator was a Sterling Alternator Protection device. This device is required in the event that our lithium batteries BMS prevents charging while the engine is running. Without the protection device there is no place to safely route the charging current of the alternator leading to possible alternator failure.
Battery Charger
Our battery charger is our second most used charging source behind our solar panels. We have a Honda 2200 onboard that we connect to the boat’s shore power to charge the batteries. On passage we typically have to run the generator each morning to keep up with our autopilot and instrumentation. On a cloudy day we will run generator to top off the batteries.
We installed a Magnum Energy 2000w inverter charger back in 2015, too old to have a lithium charge profile. We had some issues getting it to charge at the the proper voltage. The charger would see batteries sitting at 13.3v and kick into float charge mistakingly thinking we had a full lead acid battery. A quick call to tech support and we were able to fix the issue, we had to remove the temp compensation as that function is built into the BMS. We also had to adjust the re-bulk rate to account for the lithiums higher voltages.
We got the Magnum Energy inverter/charger working correctly but we ultimately decided to upgrade to a new Victron Inverter/Charger. The main reason being that our Magnum was modified sine and the Victron is pure sine. Modified sine is “dirty” power and doesn’t work for some sensitive electronics. In addition the Victron has the ability to charge a dead battery. In the event the BMS shuts down the battery due to low voltage the Magnum is unable to charge the dead battery. We had an issue with the batteries shutting down due to improper charging and we were unable to use the generator to turn the batteries back on. We actually had to get another battery and jump the bank “on” to allow the generator to start charging.
https://amzn.to/3r26sZl
