SeaMaster101
Senior Member
- Joined
- Oct 27, 2015
- Messages
- 101
- Location
- Canada
- Vessel Name
- SeaWitch
- Vessel Make
- 47' Cheoy Lee SeaMaster
I decided to share my experiences with Lithium batteries after left unattended for 26 months due to COVID Lockdown in New Zealand.
Here is how the story goes:
After crossing the Pacific Ocean on my 1972 Cheoy Lee power vessel called SeaWitch, I decided to upgrade my 18 golf cart house battery bank to lithium and after fair research I spend about 4.5k USD and ordered 3 X 300 amp/hr 12V batteries to be delivered to my vessel in Whangarei, New Zealand at the end of 2019. The batteries were ordered from Polynovel (Premium OEM Lifepo4 Battery Manufacturer | Polinovel) and contained special BMS with RS485 output, which I requested.
When I returned to the boat from my visit back home in Canada, I was very happy to find the batteries delivered to the boat.
On initial inspection I established that from the 3 batteries, two were holding exactly 13.12V but the battery number 3 was at 0.00V. I notified the manufacturer by email and they requested some pictures and videos. I have to admit, they stood behind their product and told me that they will send me a replacement battery for the one that had the problem.
We cruised NZ for couple of months on the 2 batteries and then we left NZ. That was in March 2020. Sequential the New Zealand boarder was closed for 26 months so just now I managed to get back to the boat. The replacement battery was delivered and the shipyard place it in the boat by my request.
Fist thing I did when I arrived was to check my precious four thousand dollars batteries that have been sitting for 2+ years. When I left I discharged the batteries up to 50% as recommended by the manufacturer and disconnected them completely from the vessel, but left two of them connected in parallel.
First I measured the new battery that was delivered in April 2020 (2 months after I reported to the manufacturer DOA battery problem)this new battery I presume was shipped with the same 3.1-3.2v state but after sitting for 2 years was slightly down to 12.89V. This appear to be good to me.
Next I measures the 2 batteries that was already installed and connected in parallel. They measured 13.4v due to my request to the ship yard’s Electician about 8-9months ago to connect a charger to them and charge to 13.2V -13.3V. I think he did exceeded my recommendation by little….
The cell voltages on all batteries measured within 5 or so millivolts from each other. So far, so good!
I then start dealing with the bad battery from the first shipment that had 0V. I connected just this battery to my ProMariner 1260 charger, but the charger wouldn’t start charging as it could not detect the battery. What I did them is I used my battery load tester in series ( to limit the possible high current )and connected the other batteries momentarily. That appears to make the charger to see battery and it took over. The bad battery appeared to be alive and charging. I immediately connected to my battery monitoring system and check the voltage on all 4 cell groups. Pleasantly surprised to find out that they were on few millivolts from each other and hovering around 12.8v. I changed the battery to full with about 0.2C (60A) and then decided to do capacity check with my electronic load/capacity tester. Loaded with 30A the battery was discharged to 11.0V at which state the BMS still reported 4% SOC and the total A/h consumed were 314.6 AH. I’m very happy as it appears that the battery cells are in great shape and obviously there is some glitches with the BMS that make the battery appear dead. So I might end up having 4 x 300AH battery bank, due to that fact.
I’m currently testing the capacity of the other 2 batteries that I left for 2 years connected in parallel but disconnect from the boat completely. Will report my findings when this test is completed.
I will be opening the battery that was with 0V to inspect the BMS and possibly order new one and replace it. If there is interest I will post video of the surgery…
Here are some videos from 2020 when I received the batteries and prepped for installation:
Comments are welcome
Here is how the story goes:
After crossing the Pacific Ocean on my 1972 Cheoy Lee power vessel called SeaWitch, I decided to upgrade my 18 golf cart house battery bank to lithium and after fair research I spend about 4.5k USD and ordered 3 X 300 amp/hr 12V batteries to be delivered to my vessel in Whangarei, New Zealand at the end of 2019. The batteries were ordered from Polynovel (Premium OEM Lifepo4 Battery Manufacturer | Polinovel) and contained special BMS with RS485 output, which I requested.
When I returned to the boat from my visit back home in Canada, I was very happy to find the batteries delivered to the boat.
On initial inspection I established that from the 3 batteries, two were holding exactly 13.12V but the battery number 3 was at 0.00V. I notified the manufacturer by email and they requested some pictures and videos. I have to admit, they stood behind their product and told me that they will send me a replacement battery for the one that had the problem.
We cruised NZ for couple of months on the 2 batteries and then we left NZ. That was in March 2020. Sequential the New Zealand boarder was closed for 26 months so just now I managed to get back to the boat. The replacement battery was delivered and the shipyard place it in the boat by my request.
Fist thing I did when I arrived was to check my precious four thousand dollars batteries that have been sitting for 2+ years. When I left I discharged the batteries up to 50% as recommended by the manufacturer and disconnected them completely from the vessel, but left two of them connected in parallel.
First I measured the new battery that was delivered in April 2020 (2 months after I reported to the manufacturer DOA battery problem)this new battery I presume was shipped with the same 3.1-3.2v state but after sitting for 2 years was slightly down to 12.89V. This appear to be good to me.
Next I measures the 2 batteries that was already installed and connected in parallel. They measured 13.4v due to my request to the ship yard’s Electician about 8-9months ago to connect a charger to them and charge to 13.2V -13.3V. I think he did exceeded my recommendation by little….
The cell voltages on all batteries measured within 5 or so millivolts from each other. So far, so good!
I then start dealing with the bad battery from the first shipment that had 0V. I connected just this battery to my ProMariner 1260 charger, but the charger wouldn’t start charging as it could not detect the battery. What I did them is I used my battery load tester in series ( to limit the possible high current )and connected the other batteries momentarily. That appears to make the charger to see battery and it took over. The bad battery appeared to be alive and charging. I immediately connected to my battery monitoring system and check the voltage on all 4 cell groups. Pleasantly surprised to find out that they were on few millivolts from each other and hovering around 12.8v. I changed the battery to full with about 0.2C (60A) and then decided to do capacity check with my electronic load/capacity tester. Loaded with 30A the battery was discharged to 11.0V at which state the BMS still reported 4% SOC and the total A/h consumed were 314.6 AH. I’m very happy as it appears that the battery cells are in great shape and obviously there is some glitches with the BMS that make the battery appear dead. So I might end up having 4 x 300AH battery bank, due to that fact.
I’m currently testing the capacity of the other 2 batteries that I left for 2 years connected in parallel but disconnect from the boat completely. Will report my findings when this test is completed.
I will be opening the battery that was with 0V to inspect the BMS and possibly order new one and replace it. If there is interest I will post video of the surgery…
Here are some videos from 2020 when I received the batteries and prepped for installation:
Comments are welcome
