2P4S 280A build with JK BMS for sailboat

[740GLE]

Could you rotate the BMS 90degrees?

 

[hwse]

I just finished my first cruise with my new battery and it performed fantasticlly. Most days I motored for a couple of hours which brought the battery back up to full charge but on a couple of days, I had a bit of breeze so sailed with no recharge.
Inspite of having 6 of us aboard and using the deep freeze, 12v icebox conversion fridge and the hydronic heater a couple of times each day to get hot water we never dropped below 78% SOC
I am using my old Xantex InCharge for alternator regulator but have added a 1.0ohm 100W resistor to the blue field wire which limits the output to 60A. At that level with my fully sound insulated engine bay and no blower running, it ran at 95ºC to 95ºC which is ok given that my Ample Power alt is hot rated at 100ºC but higher than I like. I turned on the bilge blower which ends about 6" away from the engine bay the temp went down to 85ºC to 90ºC. I will be extending the duct to pick up air from the above the front of the alternator so that it pulls the heated air directly out of the engine bay which should also help a great deal. I also plan to add a 120mm pusher fan to increase the airflow to further cool it. With that I should be able to crank the output by another 20A.

 

[740GLE]

What was your max current draw of the battery?

 

[hwse]

I do not have any big draws, just a lot of long term draws in the 5-7 amp range. The main ones are:

• Refer
• freezer
• hydronic boiler,
• five +3A fans on heating system
• autopilot

My daily usage is in the range of 125Ah - 175Ah so with the old 210Ah AGM. I needed to pull it down 80% and recharge fully each day which given their recharge rate is a losing proposition. I was constantly worried about SOC and would need to run my portable generator for 6 hour/day min to have any hope of keeping up. On this cruise, I never even started the generator and even on days when I motored very little, the SOC never dropped below 75% and I can safely take it down to 5% without any damage to the pack.
Looking forward to many days at quiet anchor.

 

[hwse]

After our first cruise with the new LFP battery we are thrilled. It was 6 days and 2-hours and during that time we did not give any thought to power conservation. We had the fridge, freezer, and all electronics running the whole time.
We used a total of 626 amps for an average of 102A/day. This is significantly less than we have used on any previous cruise in spite of adding the freezer. I have modified the AB icebox conversion from a mechanical thermostat to a digital that runs the compressor on low speed and eliminates the short-cycle that happens with the mechanical. I also added a much more efficient PWM controlled fan that both cools better and is completely silent. We also get a huge boost from the Peukert's ratio being 1.0 rather than the normal LA 1.25. We also get gains from the discharge voltage being 13.2v rather than 12.6 or lower for LA.
All-in-all, it comes to +30% gain in total efficiency.

 

[Marinepower]

After our first cruise with the new LFP battery we are thrilled. It was 6 days and 2-hours and during that time we did not give any thought to power conservation. We had the fridge, freezer, and all electronics running the whole time.
We used a total of 626 amps for an average of 102A/day. This is significantly less than we have used on any previous cruise in spite of adding the freezer. I have modified the AB icebox conversion from a mechanical thermostat to a digital that runs the compressor on low speed and eliminates the short-cycle that happens with the mechanical. I also added a much more efficient PWM controlled fan that both cools better and is completely silent. We also get a huge boost from the Peukert's ratio being 1.0 rather than the normal LA 1.25. We also get gains from the discharge voltage being 13.2v rather than 12.6 or lower for LA.
All-in-all, it comes to +30% gain in total efficiency.

I put 280 ah of lithium on my boat and have the some observations as you. No longer worried about charging the batteries back up to 100% and even some light motoring seems to keep up with my power needs (similar to you - fridge, freezer, instruments, some inverter use).

I like your meticulous mounting of your battery. Very tidy instal.

I'm sure you aware but one item to consider is a load dump from your alternator if /when your BMS cuts out. You need to have a lead acid battery in parallel or some other solution to absorb that energy or things are liable to get fried.

Also, seems like you are relying on the BMS to stop charging the batteries when they are full. For me, I would prefer to have some redundancy to avoid overcharging. Even a mechanical thermo fuse on the cells which in turn powers a rely which in turn powers the field wire to the alternator would be a last line of defence protection from dangerous (i.e. fire) levels of overcharge.

Better alternator solution would be a Balmar or other external regulator but there is a cost of course....

 

[hwse]

I put 280 ah of lithium on my boat and have the some observations as you. No longer worried about charging the batteries back up to 100% and even some light motoring seems to keep up with my power needs (similar to you - fridge, freezer, instruments, some inverter use).

I like your meticulous mounting of your battery. Very tidy instal.

I'm sure you aware but one item to consider is a load dump from your alternator if /when your BMS cuts out. You need to have a lead acid battery in parallel or some other solution to absorb that energy or things are liable to get fried.

Also, seems like you are relying on the BMS to stop charging the batteries when they are full. For me, I would prefer to have some redundancy to avoid overcharging. Even a mechanical thermo fuse on the cells which in turn powers a rely which in turn powers the field wire to the alternator would be a last line of defence protection from dangerous (i.e. fire) levels of overcharge.

Better alternator solution would be a Balmar or other external regulator but there is a cost of course....

Thanks.

First off, the alternator is an Ample Power 105A hot rated externally regulated alternator. The Regualtor is a Xantrex InCharge with added controls for limiting the max field current and electronic thermostatic control based on the alternator case temperature.

For alternator protection, I have an AGM start battery and they are both connected to the alternator through a diode-based combiner but that will be changing to an ArgoFET combiner. The LFP can shut off, but the AGM cannot so no diode "boom"

I am not relying on the BMS for charge cutoff. The alternator is externally regulated, and I have the charge voltage set to 14.2V (3.55v/cell) with the sense wire on the AGM side of the combiner. Absorption time is set for 30-minutes to allow the BMS to top balance the cells up to 3.55V then it drops to 13.3V for float. The active balancing comes on at 3.45V.

I have a 1.0ohm resistor on the field wire which limits the output on my 105A Ample power alternator to 60A max and keeps the temperature below 90ºC. I will also be adding a thermostatic switch to the field wire that will cut the alternator off if the output lug hits 95ºC as a safety backout. So far, the BMS has only shut down for HVC once and that was for testing purposes on the first charge. I had the charge current at 25A with the cells out of the box and no conditioning or top balance. I set the HVC at 3.55V and it tripped with 250Millivolts of delta. I then reduced the current to 2A with a 14.0v cutoff and the active balancer in the JK proceeded to top balance the cells to 3.499v with delta = 0.003V. (see screen shot.)

 

[Marinepower]

Thanks.

First off, the alternator is an Ample Power 105A hot rated externally regulated alternator. The Regualtor is a Xantrex InCharge with added controls for limiting the max field current and electronic thermostatic control based on the alternator case temperature.

For alternator protection, I have an AGM start battery and they are both connected to the alternator through a diode-based combiner but that will be changing to an ArgoFET combiner. The LFP can shut off, but the AGM cannot so no diode "boom"

I am not relying on the BMS for charge cutoff. The alternator is externally regulated, and I have the charge voltage set to 14.2V (3.55v/cell) with the sense wire on the AGM side of the combiner. Absorption time is set for 30-minutes to allow the BMS to top balance the cells up to 3.55V then it drops to 13.3V for float. The active balancing comes on at 3.45V.

I have a 1.0ohm resistor on the field wire which limits the output on my 105A Ample power alternator to 60A max and keeps the temperature below 90ºC. I will also be adding a thermostatic switch to the field wire that will cut the alternator off if the output lug hits 95ºC as a safety backout. So far, the BMS has only shut down for HVC once and that was for testing purposes on the first charge. I had the charge current at 25A with the cells out of the box and no conditioning or top balance. I set the HVC at 3.55V and it tripped with 250Millivolts of delta. I then reduced the current to 2A with a 14.0v cutoff and the active balancer in the JK proceeded to top balance the cells to 3.499v with delta = 0.003V. (see screen shot.)

Sounds like you have all the details in hand.

I use the Argofet and it stays cool even at 60 - 70 amps of charging. Seems like a good product. Not great battery lug terminals however - very small surface area. I do wonder how robust it would be if there was a voltage surge.

I have a high / low setting on the Balmar, so charge at either 40 amps or 60 amps, depending my need at the time. I use a lower bulk absorb voltage than you (14v) and then absorb charge for 20 min at 13.8v. It took awhile to dial in what charge settings worked in my system. At 14v, the bulk charging reduces the current early, but often I don't mind not getting to 100%.