Extreme Team Lithium 48V 100AH (58.4V) Pack

[PingEye3]

Question for those who have purchased and installed an Extreme Team 48V Pack. Label on pack shows max voltage as 58.4V, Charger is clearly marked as 58.4V, but pack charges to only 55V. Anyone else have that issue?? Pack voltage reads 58.4v when charge is completed and green light on charger. When charger is disconnected, pack voltage drops to 55V. ET says that is normal to settle to 55V. ?????

I have built 32 Leaf packs, and NONE have ever had the voltage 'settle' to a lower voltage when charger is disconnected. The reading I am getting from their SOC meter shows 58.4 and so does the digital dash meter, with charger connected. Smart BMS app shows 55V. 55V is measured in the BMS, the others from the load side of the pack.

These are 16 cell LifePo4 packs with max cell charging voltage of 3.65V. 3.65 x 16 - 58.4V. So it appears that the battery is never fully charged due to BMS settings which are inaccessible with the app.

If you are using an ET pack, what is your fully charged voltage??

[Volt_Ampere]

I think that may be normal for LiFe batteries. They don't have the same voltage characteristics as the Leaf cells we know and love. :-) I have some LiFe batteries for model airplane stuff and the voltage stays very constant during discharge until it is almost at zero SOC so you can't easily tell SOC from cell voltages.

[PingEye3]

Thanks Charlie, I did some research on the LiFePo4 and found a chart that confirms that voltage characteristics during discharge are much different than the Leaf modules. Just needed some re-training. The difference between SOC at 58.4 and 55V is 0.5%. Pack is all good.

Attached chart is what I found.

[Volt_Ampere]

The voltage change from 90% to 20% is minimal - probably changes that much with temperature. Measuring SOC with LiFe requires other techniques like Coulomb Counting. With my Leaf pack, I can get SOC pretty accurately with cell voltage. It's nonlinear but my home built SOC display linearizes it using a lookup table and interpolation. My SOC vs odometer is pretty good - plenty good to predict when I need to charge. I typically go 20 miles between charges. If my leaf cells were new and at full capacity (which they ain't), I would probably get almost double that distance.

[fstop]

Originally Posted by PingEye3

Question for those who have purchased and installed an Extreme Team 48V Pack. Label on pack shows max voltage as 58.4V, Charger is clearly marked as 58.4V, but pack charges to only 55V. Anyone else have that issue?? Pack voltage reads 58.4v when charge is completed and green light on charger. When charger is disconnected, pack voltage drops to 55V. ET says that is normal to settle to 55V. ?????

I have built 32 Leaf packs, and NONE have ever had the voltage 'settle' to a lower voltage when charger is disconnected. The reading I am getting from their SOC meter shows 58.4 and so does the digital dash meter, with charger connected. Smart BMS app shows 55V. 55V is measured in the BMS, the others from the load side of the pack.

These are 16 cell LifePo4 packs with max cell charging voltage of 3.65V. 3.65 x 16 - 58.4V. So it appears that the battery is never fully charged due to BMS settings which are inaccessible with the app.

If you are using an ET pack, what is your fully charged voltage??

I had a RoyPow pack with same type of cells and the voltages you are seeing are consistent with what I saw with that pack. Sounds like all is fine to me.

[WalterM6]

Sort of like a lead acid battery. You charge those anywhere from 56- 60v, the next morning they are reading 50.9. I believe the same principles are involved.

[Tom47]

Same with the ECO Battery.

[mnealuf]

I have had a ET 100ah , 48v for a couple months now and still trying to capture the capacity since the SOC is inaccurate . I still get three wildly different readings from the SOC meter, the app and the meter on the case. I understand coulomb meters have some limitations and a golf cart is widely transient so Sam,e rate etc. plays a role but I can fully charge cart, everything reads 100% and unplug the cart and let it sit a week or two and the 48v to 12v draw will pull the voltage down to say 53.1(verifies with a DMM) so the battery is really like 90% I think based on voltage sag, and yet the SOC and battery case say 100%, The slight draw is definition of steady state and yet it misses it. Maybe the balancing is consuming it. I tried to talk to the ET folks and never called me back.

[Tom47]

Originally Posted by mnealuf

I have had a ET 100ah , 48v for a couple months now and still trying to capture the capacity since the SOC is inaccurate . I still get three wildly different readings from the SOC meter, the app and the meter on the case. I understand coulomb meters have some limitations and a golf cart is widely transient so Sam,e rate etc. plays a role but I can fully charge cart, everything reads 100% and unplug the cart and let it sit a week or two and the 48v to 12v draw will pull the voltage down to say 53.1(verifies with a DMM) so the battery is really like 90% I think based on voltage sag, and yet the SOC and battery case say 100%, The slight draw is definition of steady state and yet it misses it. Maybe the balancing is consuming it. I tried to talk to the ET folks and never called me back.

In fact the battery does settle quite a bit less than 100%. Mine does around 82%. However, the SOC meter is calibrated at 100% which indicates full SETTLED charge.

I have had no issues with duplication of results irregardless of outdoor temp so far at 50 degrees. I still get 30+ miles.

[Tom47]

As a very smart man (Pat911) told me early on, LiFePo4 voltage is not linear with the SOC meter and shouldn't be considered when deciding charge status.

In fact, you should charge your LiFePo4 pack, let the charger shut off, then zero your SOC meter at 100%. This will automatically put your Amp/hour meter at full pack Ah.

You can pretty much ignore the voltage readings for all practical purposes. Start your ride at 100%, and ride until you have a 20% SOC minimum. This will give you an emergency get home charge without damaging your pack.

Remember you can charge liFePo4 every day if you want. Ten 10% charges equal ONE life cycle, just as one 100% charge equals ONE life cycle. This way I always have my pack topped off in case I get the urge to take a 30 mile ride.

That doesn't happen too much this time of year!