Lithium charging

[Tom47]

Originally Posted by Ronno6

i dunno....looks kinda complicated to me.....

I thought the same thing. If I have a problem setting it up, I'll PM WalterM6.

He knows all about it!

[Tom47]

Here's several more questions that sort of pertain to lithium charging.

Should the tow/run switch be turned off when charging? With FLA batteries, I left the tow/run on all the time except when I was working on the electrical items.

Is the same procedure used with lithium batteries? On my Alltrax, there is voltage on pin 9 whenever the tow/run is in the run position.

I'm not sure what pin 9 does internally in the Alltrax, but if it is a keep alive voltage, what should I do during and after charging?

[Pat911]

i dunno....looks kinda complicated to me.....

Ummm, that's about the simplest you can get. Can't tell if you're being sarcastic there.

If not, I apologise and you simply plug it in and turn the dial to how long you want to charge for, Anywhere from 15 minutes to 12 hours, and then turn on the switch on the side of the unit.

[Pat911]

Tom,

You can charge in either Tow or Run, it doesn't matter.

You use the TOW/RUN switch in exactly the same way you did with Lead Acid.

[Ronno6]

Originally Posted by Pat911

Can't tell if you're being sarcastic there.

Ummmmmmmmmm, ayup....

[Tom47]

Originally Posted by Pat911

Tom,

You can charge in either Tow or Run, it doesn't matter.

You use the TOW/RUN switch in exactly the same way you did with Lead Acid.

Thanks, Pat!

[Pat911]

Originally Posted by Ronno6

Ummmmmmmmmm, ayup....

[TMZ222]

Originally Posted by Pat911

Hi,

Leaving a charger connected to a lithium battery indefinitely is not recommended, neither is relying on the BMS to stop charging. In your current situation you only have a single point of failure before you start overcharging your battery, the BMS.
In normal use, the BMS should never trip off, either charging or discharging.


If I were you, I would lower the charge voltage if you can, that will have two benefits, it will lengthen the life of your battery and will not let the battery voltage get high enough to trip the BMS. I would then get a timer and use it as has already been described.

You will then actually have 3 points of failure before you damage your battery.
Firstly, the charge voltage will never be high enough to overcharge the battery.
Secondly, if the charger fails and puts out a higher than acceptable voltage, the BMS will do its job and trip off
Thirdly, if all else fails, the timer will shut off, stopping charge.

The timer will also have the added benefit of not continuously saturating the battery. That is not good for lithium.

In battery backed solar installations they use an MPPT charge controller to control the current coming from the solar panels. That is totally seperate to the BMS protecting the battery pack. As stated, the BMS should never trip off, if it does, you have a problem somewhere.

Cheers
Pat.

Thanks Pat for the reply and I’m also going to go with that timer.
And thanks Tom didn’t want to seem like I was stepping on any toes asking questions here.

[Tom47]

Originally Posted by TMZ222

And thanks Tom didn’t want to seem like I was stepping on any toes asking questions here.

You're welcome TMZ!

[dc.901]

Originally Posted by WalterM6

Your getting LiFePo4 and NMC batteries run together. For a Nominal 48v pack a LFE has 16 cells and is charged to 58.4 for a single cell voltage of 3.65V. A NMC(aka Leaf) has 14 cells and is charged to 58.8 for a individual cell voltage of 4.2v.

I've the Bigbattery BDGR kit 2x48v (80Ah)... It exhibits something similar as others mentioned; fan on the charger never shuts off.

The battery monitor/meter I have shows that once the voltage reaches 50.1v it does not go any higher. I've confirmed this also with a multimeter.

BB datasheet on these BDGR (NMC) batteries has top cut-off voltage to 50.1v, which is exactly I am seeing.

So, if NMC batteries could reach 58.8v then they have the BMC programmed to cut off charging at 50.1 (~15% less).

It sounds like I also need to get that timer...