On board charging system verses BMS system in Lithium Batteries

I recently purchased and installed a quality lithium battery with supposedly a quality BMS system. I also purchased a recommended two bank on board charger which has the capability to charge regular wet cell battery and able to choose second battery as a lithium battery with a protection system of over charging, also prevents charging when conditions are too hot or to cold. In short both systems have ultimate protection for battery.

My question is this, once the battery goes to full charge either the BMS system in the battery stops letting it charge or the charger does. It doesn’t seem to work like the wet cell side and continue to keep trickle charging.
The question, is this normal with a lithium battery?

Appreciate you guys input as the electrical side of things continues to be my weakness with any system.


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What brand and Amp hour is battery? Does it have a Bluetooth app where you can see the individual cell voltages of the battery?

What brand and model is the charger?

Do you have a master cut off switch on the Lithium battery? What are you powering with the Lithium battery? Is there a chance it is having a little power being drawn from the battery and the charger keeps topping it off.

Zekepa, thank you for your response.
I am using the same brand as I have been using on my RV toy hauler. With good results and service.
Vatrer but on the boat it is a deep cycle marine battery 12V 50Ah.

There is no blue tooth on this small battery. I am running the LiveScope with a Garmin 93SV with the 32 transducer.

I am charging the battery with, a Noco genius Gen 5x2 charger with settings set for lithium battery.

I do have a master cut off switch.
I am only running LiveScope off of this battery.

It simply changes up and once it’s charged up it kicks the charger offline and does not do like the wet cell lead battery does and continues to take a trickle charge.

Just wondering is that normal for the BMS system to do that or possibly the charger only on the lithium battery?


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By the way, I keep the master switch cut off and only on during the use of the LiveScope.


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I initially miss read what you were asking. I thought the charger was continuing to trickle charge the Lithium battery. I thought maybe something was drawing some power when you didn't intend for it to do that. The cutoff switch makes that impossible.

Anyways. I also use a NOCO charger but haven't really paid attention to the difference between it charging the one lead acid battery I have on board vs how it is charging the Lithium batteries.

You question got me curious. Doing a little research here BU-409: Charging Lithium-ion - Battery University Lithium batteries are not designed to have a trickle charge applied to them. Once charged to a specific voltage you don't want them to overcharge.

Looking at the specs for your battery it is designed to be charged at 14.2 to 14.6 volts. The company recommends a 14.6V charger. The NOCO charger in Lithium mode is supposed to be 14.6 Volts.

I can't accurately say whether it is the Battery BMS stopping the charge (I suspect it probably is, as they design it to the specs they want to protect the battery from being overcharged, probably a tighter tolerance) or the NOCO Charger (I suspect the tolerance is probably wider).

The important part is that one of them is protecting the battery from being overcharged. I've heard some Lithium batteries don't have a BMS (all my Lithium Batteries have a BMS and a Bluetooth app, I can even see what voltage the 4 individual cells inside the battery are charged to) for those batteries without a BMS, you would have to rely on the charger stopping the charge to avoid overcharging.

I personally would want a battery with a BMS.

No need for trickle charging on a lithium ion battery.

Thank you sir, it definitely appears that you are much more knowledgeable on this subject matter than me.
I felt that it was the BMS system on the battery kicking it off.
I have a buddy that didn’t research lithium batteries very well his had a BMS system but it didn’t keep it from overcharging and he has had issues. He has the same charger but his battery wasn’t purchased with the BMS system in mind. His lithium battery would stay on trickle charge on his just like the wet cell lead battery would.
Thanks again for researching and helping me. There is a lot that one can learn in addition to crappie fishing by being a member.


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If his is switching over to trickle charge, he should make sure the mode is set to Lithium. If it's still doing it I would not leave it plugged in all the time. Once it starts to do a trickle charge I would unplug the charger.

I work on electronic systems for the Army. Your question got me curious so I learned some new stuff today also. The people here are great at helping each other out.

Again thank you sir. As for the Crappie .com group helping one another “absolutely”!!!


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