16S 120Ah from XUBA - Capacity Test and putting into service in a Golf Cart

[AussieInSeattle]

My 16S 120Ah order from XUBA ($837 shipped via sea to Seattle) should arrive the first week in September so I've done a lot of reading on what to do when they arrive. I've come up with the following approach for doing a capacity test as quickly as I can with only having to purchase minimal items - anyone have any comments on this approach? I know I could buy one of those 150watt single cell capacity testers but even with "only" 120Ah cells it would take a long time to test each one based on my calculations - they'd also take a month to get here so would need to order asap if my calcs are wrong

Items I have already that will be used when golf cart is put into service:

• Golf cart - 2011 Precedent with AllTrax 500amp controller and Admiral MOT-A2 speed motor - 12" wheels (these things will all matter for real world capacity test)
• 1200 watt heat gun
• 16S 30Amp Bluetooth BMS
• Relays, etc to control charge and discharge cutoff (need these as a golf cart can draw 200+ amps)
• 10Amp 58.8 volt (adjustable) AC charger
• Renogy Battery monitor to track capacity remaining once pack is in use

Items I'll have to buy for capacity test (~$390):

• 100 Amp shunt based battery monitor that shows Wh consumed ($20 on amazon)
• Two 8S battery monitors - could also get this info via BMS Bluetooth app but this is easier ($30ea on amazon)
• 1500 watt AIMS 48v inverter ($250 at home depot) - will likely sell on Craigslist once I am done testing to recoup some of my cost
• CC/CV 10Amp adjustable DC power supply recommended by Will ($60 on amazon)

STEP 1 - TOP BALANCE:

1. Upon arrival put cells in 16P using XUBA supplied busbars for 48 hours
2. Put cells in 16S and hook up 30Amp BMS and set BMS to HV cutoff of 3.6 volts per cell
3. Hook up two 8S battery monitors so I can watch voltage per cell (easier than phone based app)
4. Charge 16S pack using 10Amp AC charger I purchased for the golf cart - charger set to 57.6 vols (3.6 volts per cell)
5. Put cells in 16P again and use CV/CC power supply (recommended by Will) set to 3.625 volts and wait for amp draw to drop to 0

STEP 2 - CAPACITY TEST (did I get what I paid for):

1. Put cells in 16S and hook up 30Amp BMS and set BMS to LV cutoff of 2.5 volts per cell
2. Hook up 100 amp shunt based battery monitor that measures cumulative Wh
3. Use AIMS 1500 watt 48v inverter (90% efficiency) and 1200 watt heat gun - at 1200 watts and 90% efficiency I should draw 1333 watts per hour from the pack - run heat gun and check watts draw on battery monitor from step 2
4. Pack should start with 6960 watts (3.625 x 16 x 120) so expect the BMS to cut off after about 5 hours and 13 minutes - pretty close to a 0.2C discharge
5. Analyze test results

STEP 3 - PREP PACK FOR PUTTING INTO SERVICE:

1. Charge thedepleted 16S pack using the 10 Amp AC charger and take note of voltage via the shunt based battery monitor when I've put 90% of the charge into the pack and 95% - can get these total watts numbers by multiplying Wh from capacity test above by .9 and .95
2. Once charging has finished, set charger to desired absorption voltage (90%, 95% or 100%) - will likely use 90% as I have lots of capacity for my needs
3. Set BMS settings appropriately to match charger voltage for HV cutoff from step 2 above and set LV cutoff to 3V per cell
4. Remove the 100amp battery monitor
5. Hook up shunt based 500 Amp Renogy battery monitor and set its 100% Ah capacity based on above settings - this will be used to track remaining Ah while cart is in service - due to cart pulling 200+ amps at times my 100Amp monitor would not work - Renogy monitor does not track Wh so cannot use it for capacity test - also like the appearance/layout of the Renogy monitor over the cheaper ones

STEP 4 - REAL WORLD CAPACITY TEST:

1. Fully charge pack to whatever I decided above (90% capacity)
2. Use golf cart until BMS cuts out - track how many miles I drive via phone app, how aggressive I drive, hills, etc - expecting this to take 3-4 rounds of golf (20-25 miles) and errands
3. Analyze results - this capacity test is moreso for likely questions I'll get regarding "how many miles can you drive with a 120Ah pack?"

 

[legacyturbo]

"STEP 1 - TOP BALANCE:

1. Upon arrival put cells in 16P using XUBA supplied busbars for 48 hours"

If you put them in parallel you have to load them till at least 3.5V better 3.6V to top balance. Just to put the cells in parallel and just wait will help nothing.

 

[Gazoo]

Put cells in 16P again and use CV/CC power supply (recommended by Will) set to 3.625 volts and wait for amp draw to drop to 0

Why don't you make this the first step? I am not going to use the power supply recommended by Will. I am going to use a single cell lifepo4 charger or an R/C hobby charger. Not willing to take the risk of ending up with a bloated cell. I didn't want to top balance in the first place but have decided to.

 

[AussieInSeattle]

Why don't you make this the first step? I am not going to use the power supply recommended by Will. I am going to use a single cell lifepo4 charger or an R/C hobby charger. Not willing to take the risk of ending up with a bloated cell. I didn't want to top balance in the first place but have decided to.

@legacyturbo - Thanks - did not know that I needed a higher voltage for that to work - should I just skip that step (step 1.1) entirely?

@Gazoo - How is there a risk of a bloated cell if I am charging a 16S pack with a BMS or a 16P pack via a CC/CV charger?

 

[Craig]

@legacyturbo - Thanks - did not know that I needed a higher voltage for that to work - should I just skip that step (step 1.1) entirely?

@Gazoo - How is there a risk of a bloated cell if I am charging a 16S pack with a BMS or a 16P pack via a CC/CV charger?

There is no risk if you trust BMS to stop charging at 3.65v

 

[AussieInSeattle]

There is no risk if you trust BMS to stop charging at 3.65v

Good point - I'll add a test step in to set BMS to cut off at something like 3.4v first to ensure it is working correctly since it will be it's first use.

 

[Craig]

My 16S 120Ah order from XUBA ($837 shipped via sea to Seattle) should arrive the first week in September so I've done a lot of reading on what to do when they arrive. I've come up with the following approach for doing a capacity test as quickly as I can with only having to purchase minimal items - anyone have any comments on this approach? I know I could buy one of those 150watt single cell capacity testers but even with "only" 120Ah cells it would take a long time to test each one based on my calculations - they'd also take a month to get here so would need to order asap if my calcs are wrong

Items I have already that will be used when golf cart is put into service:

• Golf cart - 2011 Precedent with AllTrax 500amp controller and Admiral MOT-A2 speed motor - 12" wheels (these things will all matter for real world capacity test)
• 1200 watt heat gun
• 16S 30Amp Bluetooth BMS
• Relays, etc to control charge and discharge cutoff (need these as a golf cart can draw 200+ amps)
• 10Amp 58.8 volt (adjustable) AC charger
• Renogy Battery monitor to track capacity remaining once pack is in use

Items I'll have to buy for capacity test (~$390):

• 100 Amp shunt based battery monitor that shows Wh consumed ($20 on amazon)
• Two 8S battery monitors - could also get this info via BMS Bluetooth app but this is easier ($30ea on amazon)
• 1500 watt AIMS 48v inverter ($250 at home depot) - will likely sell on Craigslist once I am done testing to recoup some of my cost
• CC/CV 10Amp adjustable DC power supply recommended by Will ($60 on amazon)

STEP 1 - TOP BALANCE:

1. Upon arrival put cells in 16P using XUBA supplied busbars for 48 hours
2. Put cells in 16S and hook up 30Amp BMS and set BMS to HV cutoff of 3.6 volts per cell
3. Hook up two 8S battery monitors so I can watch voltage per cell (easier than phone based app)
4. Charge 16S pack using 10Amp AC charger I purchased for the golf cart - charger set to 57.6 vols (3.6 volts per cell)
5. Put cells in 16P again and use CV/CC power supply (recommended by Will) set to 3.625 volts and wait for amp draw to drop to 0

STEP 2 - CAPACITY TEST (did I get what I paid for):

1. Put cells in 16S and hook up 30Amp BMS and set BMS to LV cutoff of 2.5 volts per cell
2. Hook up 100 amp shunt based battery monitor that measures cumulative Wh
3. Use AIMS 1500 watt 48v inverter (90% efficiency) and 1200 watt heat gun - at 1200 watts and 90% efficiency I should draw 1333 watts per hour from the pack - run heat gun and check watts draw on battery monitor from step 2
4. Pack should start with 6960 watts (3.625 x 16 x 120) so expect the BMS to cut off after about 5 hours and 13 minutes - pretty close to a 0.2C discharge
5. Analyze test results

STEP 3 - PREP PACK FOR PUTTING INTO SERVICE:

1. Charge thedepleted 16S pack using the 10 Amp AC charger and take note of voltage via the shunt based battery monitor when I've put 90% of the charge into the pack and 95% - can get these total watts numbers by multiplying Wh from capacity test above by .9 and .95
2. Once charging has finished, set charger to desired absorption voltage (90%, 95% or 100%) - will likely use 90% as I have lots of capacity for my needs
3. Set BMS settings appropriately to match charger voltage for HV cutoff from step 2 above and set LV cutoff to 3V per cell
4. Remove the 100amp battery monitor
5. Hook up shunt based 500 Amp Renogy battery monitor and set its 100% Ah capacity based on above settings - this will be used to track remaining Ah while cart is in service - due to cart pulling 200+ amps at times my 100Amp monitor would not work - Renogy monitor does not track Wh so cannot use it for capacity test - also like the appearance/layout of the Renogy monitor over the cheaper ones

STEP 4 - REAL WORLD CAPACITY TEST:

1. Fully charge pack to whatever I decided above (90% capacity)
2. Use golf cart until BMS cuts out - track how many miles I drive via phone app, how aggressive I drive, hills, etc - expecting this to take 3-4 rounds of golf (20-25 miles) and errands
3. Analyze results - this capacity test is moreso for likely questions I'll get regarding "how many miles can you drive with a 120Ah pack?"

Putting them in series is the fastest way to charge them. Just know that they may not all reach the top voltage at the same time so you may need to manually charge some to get them up to 3.6. I charge them in series for bulk then finish individually or 2 to 3 at a time in parallel.

 

[Craig]

Overall I think you have a good plan. I test cells individually so I know the exact data for each cell. However the drawback is that it takes some time as I can only test 4 cells at once as I only have 4 testing units. Gonna build more in my SPARE time lol.

 

[AussieInSeattle]

Overall I think you have a good plan. I test cells individually so I know the exact data for each cell. However the drawback is that it takes some time as I can only test 4 cells at once as I only have 4 testing units. Gonna build more in my SPARE time lol.

Hmm SPARE time - haven't found that on Alibaba yet . I read your thread on how you are doing your testing - thanks for chiming in.

Even if I only get 100Ah or 110Ah for my results I'll be fine (despite not getting what I paid for) - that will still be 3 rounds of golf per charge I think - six cheap 8v FLA batteries for my golf cart run around $700 and goes beyond $1000 for better quality and my current set lasted <5 years - even at reduced Ah I'll be coming out well ahead for my application. I'll likely only do 50 cycles per year so these "should" be the last set of batteries I buy.

 

[Gazoo]

I think I am

@Gazoo - How is there a risk of a bloated cell if I am charging a 16S pack with a BMS or a 16P pack via a CC/CV charger?

I am referring to top parallel balancing. 16P. There have been reports of users accidentally over charging their cells using a bench top power supply and ending up with bloated cells. I have come to the conclusion, and I think it's a good idea, that the safest way to top balance is to use a single cell 3.65 volt charger or program an R/C hobby charger to charge a single cell lifepo4 battery. That's what I am planning on doing. I have no need for a bench top power supply however a hobby type R/C charger might come in handy. I do understand why you want to charge the batteries first in a 16S configuration and the rest of your steps look very good to me. And I like your idea of testing the BMS to cut off at 3.4 volts. But I am not willing to take the risk of using a bench top power supply. Not saying I am against it. But it's not for me.

 

[AussieInSeattle]

One potential issue I just came across in my list of testing components is the 100A battery monitor - link below is the 300A version. From what I can tell the Wh will only increase when I am discharging as part of the capacity test (according to amazon reviews). So it appears I cannot use this device for Step 3.1 when I want to take note of the voltage at 90% of my Wh capacity when I am charging? Anyone know of a battery monitor that I can use to measure discharge Wh (Step 2.2) and charge Wh (Step 3.1)

Robot Check

 

[Craig]

One potential issue I just came across in my list of testing components is the 100A battery monitor - link below is the 300A version. From what I can tell the Wh will only increase when I am discharging as part of the capacity test (according to amazon reviews). So it appears I cannot use this device for Step 3.1 when I want to take note of the voltage at 90% of my Wh capacity when I am charging? Anyone know of a battery monitor that I can use to measure discharge Wh (Step 2.2) and charge Wh (Step 3.1)

Robot Check

reset it and turn it around so that it thinks it is discharging when you are charging.

 

[AussieInSeattle]

reset it and turn it around so that it thinks it is discharging when you are charging.

makes sense - to confirm i could do either of these?:
in the 5th image on the amazon ad I can just swap the blue and yellow wires (cant find an image to see if this is easy via ring terminals)
OR
flip the shunt so blue wire is on the load side and yellow wire is on battery side

 

[Gazoo]

One potential issue I just came across in my list of testing components is the 100A battery monitor - link below is the 300A version. From what I can tell the Wh will only increase when I am discharging as part of the capacity test (according to amazon reviews). So it appears I cannot use this device for Step 3.1 when I want to take note of the voltage at 90% of my Wh capacity when I am charging? Anyone know of a battery monitor that I can use to measure discharge Wh (Step 2.2) and charge Wh (Step 3.1)

Robot Check

I like mine as it measures in both directions. I believe it measures coulombs accurately. Most of these cheap meters have problems with accurate capacity readings. I reset mine when I discharge and charge. Other than that I am really happy with it. I have the 100 amp version but they make up to a 300 amp version.

juntek battery monitor - Buy juntek battery monitor with free shipping on AliExpress

Quality juntek battery monitor with free worldwide shipping on AliExpress

www.aliexpress.com

There are youtube videos to reference concerning the meter.

 

[AussieInSeattle]

I like mine as it measures in both directions. I believe it measures coulombs accurately. Most of these cheap meters have problems with accurate capacity readings. I reset mine when I discharge and charge. Other than that I am really happy with it. I have the 100 amp version but they make up to a 300 amp version.

juntek battery monitor - Buy juntek battery monitor with free shipping on AliExpress

Quality juntek battery monitor with free worldwide shipping on AliExpress

www.aliexpress.com

There are youtube videos to reference concerning the meter.

Thanks - will see if I can get one here quick enough. This meter is only for capacity testing and finding by 90% / 95% capacity. I plan on using the Renogy one for full time monitoring once the pack is in service on the cart.

 

[Gazoo]

Please keep us updated. I will be interested to know how many miles you can go in your golf cart with the new cells.