Lithium Batteries

[Maine Sail]

I have been monitoring my new LFP batteries for a few months now. 2) 100 Ah LIFEPo4 smart batteries, My only real issue is that the 2 batteries generally don’t have the same SOC, except maybe after charging them independently at 14.6 volts (per mfg recommendation).

But despite the SOC issue, the batteries work well and typically share the house load just fine, and almost always have the same voltage . After a sail…
View attachment 234412 View attachment 234412
And today after sailing 3.5 hours…
View attachment 234414 View attachment 234415

I have yet to have any concerns about heat or fire with these batteries.

Greg

Impossible to help without brand/model... Keep in mind the accuracy of the SoC counters in the BMS are not pin point accurate they are a guide. If you have multiple batts in parallel you will want a shunt based BMS & balanced bank wiring. Always start with well balanced batts before wiring in parallel. Tap on the round V button and show us the cell balance. You do not want to be charging at 14.6V as this is the absolute max. 14.2V is far safer...

 

[Maine Sail]

Yes, these are a new set of 2) Humsienk 100Ah 12v smart batteries. Yes, they have Bluetooth, so I can monitor the status.

They are wired to the house load only, and are NOT charged at all by the alternator.

L ike I mentioned, HumsiENK gave me the charge parameters to “equalize” the batteries before connecting them in parallel. This was supposed to get the. Both 100 SOC and same voltage. That is not my daily charge profile. I am using a Victron charger with a Li-Ion profile.

Unfortunately, the HumsiENK app will not display the individual cell voltage. They told me they are working on it (apparently in conjunction with WattCycle), but not available yet.

i don’t think that the both of the BMs’s are shutting off at any given point. But you will see some times where one or the other battery is not contributing to the load. Usually when the load is very light. But one battery is always keeping the lights and radio on…

I have been one the hook for 2 days (going on second night tonight) and have been monitoring the battery status in a spreadsheet. I will share that if anyone cares. I don’t really have a way to charge when off shore power, except to jump the start battery to the house bank when the engine is on and the alternator is charging the starter battery. Not very efficient, and today, I motored a total of 30 minutes.

Home tomorrow and back on shore power.

Greg

Humsienk batts have over-charge protection in both BT & non BT batts, just like Wattcycle. Wattcycle is extremely responsive and already has a fix I don't believe Humsienk has addresed it yet as these are loss-leader batts.

 

[Tally Ho]

Humsienk batts have over-charge protection in both BT & non BT batts, just like Wattcycle. Wattcycle is extremely responsive and already has a fix I don't believe Humsienk has addresed it yet as these are loss-leader batts.

Oddly, when I wrote to HumsiENK about an updated app, I got a response from WattCycle…

Is there any connection between these 2 companies that you are aware of?

Separately, here is the latest note I have received from HumsiENK…

The issue you’re seeing with batteries not staying perfectly in sync when paralleled is a common phenomenon across lithium batteries. Our team is already working on optimizing the app to improve monitoring and ease of use.

Impossible to help without brand/model... Keep in mind the accuracy of the SoC counters in the BMS are not pin point accurate they are a guide. If you have multiple batts in parallel you will want a shunt based BMS & balanced bank wiring. Always start with well balanced batts before wiring in parallel. Tap on the round V button and show us the cell balance. You do not want to be charging at 14.6V as this is the absolute max. 14.2V is far safer...

The 14.6 v charge was only to try and get both batteries ( charged independently) to 100% SOC before wiring them in parallel. This instruction came from Humsienk. They also said limit the amps to 5. Charge for a couple of hours.

It seemed to help.

When I was out this week, this was the state of the batteries after charging…
Both batteries at the same voltage and a % difference in SOC


After sailing, and before I put them back on the charger…identical.


Greg