deeznutz206
New member
Meant the battery. Got it, I'll wait for your testing!
Building 180Ah 12V LiFePO4 power pack
- Thread starter ShamusTX
- Start date
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Observer
My shipping updated and it's due 9/21 which isn't bad. It's weird because the country of origin appears to be US, as the label was created in the United States on 9/11, and sat in awaiting delivery to UPS facility (or something of that nature) until 3 hours ago and is in Cerritos, CA.
The funny thing is the package weight is listed at 31lbs, which for naked cells puts it in line with 100ah or a smidgen over (Battleborn with their plastic case and electronics is 31lbs on their 100ah 12v batteries). So, it seems highly unlikely that I'll be receiving anything near the advertised capacity. If that was their mistake then I'm not too keen on shipping them back (almost certainly at my expense) and running the risk of never hearing from them again.
I'll weigh and get a capacity test rolling the second they arrive, but if I got shorted I'll go ahead and ruin their company. If they're actually in CA and I can track them down... some ding dong will be eating a battery. If you needed a reason to buy CALB cells from the original poster's source, here it is. Truth be told, actual 100ah won't ruin my plan. But I probably would have bought some ~$600 100ah drop in replacement that Will Prowse has evaluated. Though if I could go back in time, I would have re-read this thread and ordered the CALB from aliexpress.
Edit people are awake in China and seller responded to my concerns instantly by sending a screenshot from their logistics system showing 18.3kg (or 40.3ish lbs). In my googling, one can expect 90-110 watt hours per kg of battery. So if shooting in the middle, 18.3kg * 100 = 1830 watt hours, or 18.3 * 110 = 2013 watt hours. I should be receiving 608wh per cell or 2432 watt hours. Now that's assuming the box and protective shipping materials magically weighed nothing, and the housing, wrap, and terminals also weighed nothing. Seems highly unlikely. Will update. Not to hijack thread OP, but I still feel you chose wisely.
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Lesson - get the exact weight per cell before pulling the trigger.
Not a guarantee of positive but definitely so the other way.
Some marketeers us "equivalent" Ah, based on lead being 50% usable.
99.9% cannot imagine an individual customer being able to accurately test for capacity, resistance etc upon receipt.
But shipping cost back to China means little recourse unless PayPal / credit card will go to bat for you, I doubt AliPay will.
Definitely a business opportunity here if a good supply chain could be established selling from Canada or the US, definitely worth paying 20-30% margins for lower risk factor.
Not a guarantee of positive but definitely so the other way.
Some marketeers us "equivalent" Ah, based on lead being 50% usable.
99.9% cannot imagine an individual customer being able to accurately test for capacity, resistance etc upon receipt.
But shipping cost back to China means little recourse unless PayPal / credit card will go to bat for you, I doubt AliPay will.
Definitely a business opportunity here if a good supply chain could be established selling from Canada or the US, definitely worth paying 20-30% margins for lower risk factor.
luthj
Engineer In Residence
Prismatic cells have less case material than packs made from many cylindrical cells, so they tend to be slightly lighter per AH. If this is a major dealer (bulk and small orders) I would guess you are getting something legitimate. It may not be like CALB level (with 10% extra capacity above rated).
The CALB batteries I got have a very thick casing and weigh 12.5lbs each. They are 7" wide and 3" deep and 5.7Kg. Your link to the battery page on Aliexpress shows the blue batteries and looking at the 190Ah cell it only weighs 4Kg each. That would mean four of these would only be 35lbs plus packaging. Also the dimensions state that they are only 2" deep and 7" wide. So the CALB has more plastic and internal stuff then the Blue colored cells. Which means you probably got 195Ah cells, but have to weight until you get them to be sure.
The way they my supplier shipped from China to meet the time line Alibaba imposed on the suppliers, is to create a US shipping notice within 7days of the order and report this to Alibaba. The pacakge was actually shipped from China. Alibaba gives them 7 days to ship the package and then another 15 for it to be delivered. My supplier created a UPS notice in LA and shipped it from China to LA where it was handed off to UPS and ground shipped to TX. Took the full 22 days that Alibaba gives for the package to be delivered.
hour
Observer
Ah that makes sense. Crafty, I guess. But glad you and luthj think there's a chance I got cells at least in the ballpark of the advertised capacity. Pretty set on using the ammo can you used, so that'll give me more room in the front of the box to fiddle with wiring - bms - active balancer. I have a lot of medium density foam from gun cases and pelican knockoff cases to pack them in tight, but it seems like you were getting encouragement to ensure absolutely zero movement. I used 3M VHB tape to attach my plastic cased cells in my current LFP setup and that has done an outstanding job to prevent movement between each. This might not work on these blue wraps as well as it did the plastic cased, since the wrap may stretch. Anyway, thanks for the encouragement and ideas.
So I received two GigaVac Gx21SB 150A contactors, the 150A is the smallest I could find. Theses are 12V Dual coil. Once the contactor is closed they only consume 82mA @ 12V to hold it closed.
I also made mounts for these, due to space limits I had to stack them. The 0.19" plates they are mounted to are also used to straighten the box. There is one plate on each side with the custom Band clamps.
Waiting on the BMS to rewire the box.
I also made mounts for these, due to space limits I had to stack them. The 0.19" plates they are mounted to are also used to straighten the box. There is one plate on each side with the custom Band clamps.
Waiting on the BMS to rewire the box.
luthj
Engineer In Residence
Sensata | Gigavac | Sensata Technologies
GIGAVAC GX21SCB DC Contactor
GIGAVAC GX21SCB DC Contactor. 150A, 12Vdc, NO Contact. GX21SAB Contactors can switch DC loads at both low and high voltage from 12 to 800VDC.
dc-components.com
Short answer, No real large loads, max load current currently would be ~60ish amps. Primary reason was the possibility for High Voltage Disconnect issues with MOSFET BMS with my original design.
Long Answer with more details:
Originally I did not have any backup protection on the solar controller. I only had a MOSFET based BMS on the inverter / AC Charger port. I was going to rely on the solar controller programming to not charge above 80% SoC and to cut out the DC loads at 15% SoC. But after thinking about the design more and based on feedback, I decided I needed to have a backup to the solar controller. Another problem I was concerned with is the possibility of High Voltage Disconnect issues when MOSFET BMS opens the Solar charger or AC charger port with either still charging and damaging DC devices on the load side. So I figured the mechanical route was a good choice. As for why these contactors, the Dual Coil contactors have a very low keep closed current consumption, only 82mA. In a 24hr period the 2 contactors would only consume ~8Ah verse a normal relay with a 1A keep closed current consuming 48Ah.
Since then I have decided to rewire and have one port dedicated to Solar or AC charging. Max current on input is 20A from the AC charger or 15A from solar. The solar charger would still be programed to cut off at 80%, BMS would back it up and cutoff at 90%. The AC charger charges to 100%, not programmable, so the BMS would again cutoff at 90%.
Then another port dedicated to DC loads. The DC loads are things like a National Luna 90L fridge, DC LED lights with Bluetooth & WiFi controllers, mobile device charging and a 500W inverter.
My solar controller only supplied voltage for the pack and did not provide any details about SoC. So I need something to display SoC and other information. When I acquired the relays I also picked up a Chargery BMS8T which is able to control them. The Chargery has a Charge relay control port and a Load relay control port. It also has the capabilities to monitor Amps in and out, via shunt, monitor individual cell voltages, monitor temperature and display SoC. But, it only connects to Relays or contactors, and does not have High Power MOSFETs.
I mentioned this in another thread - but I am not convinced there is an issue with BMS high voltage disconnecting. I have certainly not seen anything in running a LiFePO4 battery with a MOSFET based BMS for several years, and I have not heard of anything from the thousands of folks running Battleborn batteries with MOSFET BMS built in. Again if you suspect this might be an issue a clamping diode (TVS) across the output ports will protect against this.
I hate to say it, but I think your new setup will cause you many more problems than the Deligreen you had previously.
Charing based on SOC is a risky and unnecessary proposition. Coulomb counting SOC estimates are subject to integration errors - that is to say the small inherent errors in measuring current add up over hours, days and weeks to very large errors in SOC. The way Victron and other coulomb counting meters deal with this is to resync the SOC accounting on every full charge - ie when the voltage gets to some level that is indicative of 100% SOC (say 13.8V on a LiFePO4) then it resets the SOC to 100%. The problem is if you only charge to 90% SOC, you never have an opportunity to resync and the SOC measurement will get way out of sync from your batteries actual SOC.
It would be much more reliable just to use voltage to terminate charge - which is how everyone else does it. I am guessing you are trying to maximize battery cycle life by not charging to 100%, but this is more easily done by setting your charge voltage to 3.4 - 3.5 V/cell and is a secondary concern at best.
I don't know what your usage scenario is - but 8Ah a day to run the BMS and relays is a huge parasitic load and your battery will be dead flat if it sits for even a month. Typical MOSFET BMS have parasitic loads in the micro-amps. This may or may not be an issue for your particular usage scenario, but would be an issue for most camper batteries.
The Chargery BMS looks nice and gives you great feedback, but I would disable the SOC limits and switch to using MOSFETs (or Solid state relays) set on voltage limits. You could safely use the low SOC trigger to shut off the loads, but a low voltage limit should work fine for this too.
I hate to say it, but I think your new setup will cause you many more problems than the Deligreen you had previously.
Charing based on SOC is a risky and unnecessary proposition. Coulomb counting SOC estimates are subject to integration errors - that is to say the small inherent errors in measuring current add up over hours, days and weeks to very large errors in SOC. The way Victron and other coulomb counting meters deal with this is to resync the SOC accounting on every full charge - ie when the voltage gets to some level that is indicative of 100% SOC (say 13.8V on a LiFePO4) then it resets the SOC to 100%. The problem is if you only charge to 90% SOC, you never have an opportunity to resync and the SOC measurement will get way out of sync from your batteries actual SOC.
It would be much more reliable just to use voltage to terminate charge - which is how everyone else does it. I am guessing you are trying to maximize battery cycle life by not charging to 100%, but this is more easily done by setting your charge voltage to 3.4 - 3.5 V/cell and is a secondary concern at best.
I don't know what your usage scenario is - but 8Ah a day to run the BMS and relays is a huge parasitic load and your battery will be dead flat if it sits for even a month. Typical MOSFET BMS have parasitic loads in the micro-amps. This may or may not be an issue for your particular usage scenario, but would be an issue for most camper batteries.
The Chargery BMS looks nice and gives you great feedback, but I would disable the SOC limits and switch to using MOSFETs (or Solid state relays) set on voltage limits. You could safely use the low SOC trigger to shut off the loads, but a low voltage limit should work fine for this too.
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As soon as a bank is no longer cycling, going into "storage mode", should include dropping OCV, and if for a long period, isolating the cells from everything, including the BMS.
Not just for the sake of eliminating vampire load drains
but preventing the (many) bank failures, damage to very expensive cells, due to failures of the ancillary hardware infrastructure.
A single monolithic "BMS" gadget is not always the way to go, in reality if possible a minimalist approach is better, look at the actual functionality needed.
HVC is only needed while SoC is low, and charge inputs are active.
LVC is only needed while feeding loads.
Monitoring for relative imbalances does not need to be 24*7 while in operation, best done at the end of the charge cycle for top balancing.
Emergency cutoff for gross cell failure can be handled with mid-point tap monitoring.
Temperature protections depends on context.
Not just for the sake of eliminating vampire load drains
but preventing the (many) bank failures, damage to very expensive cells, due to failures of the ancillary hardware infrastructure.
A single monolithic "BMS" gadget is not always the way to go, in reality if possible a minimalist approach is better, look at the actual functionality needed.
HVC is only needed while SoC is low, and charge inputs are active.
LVC is only needed while feeding loads.
Monitoring for relative imbalances does not need to be 24*7 while in operation, best done at the end of the charge cycle for top balancing.
Emergency cutoff for gross cell failure can be handled with mid-point tap monitoring.
Temperature protections depends on context.