05-21-2021, 09:55 AM | #21 |
Gone Wild
Join Date: May 2012
Location: Rio Verde, Az
Posts: 7,125
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Re: Is RoyPow a fake company??
@Pat911, I agree with you on all of that! The big drop in lithium battery prices was several years ago. The Leaf cell (and most other EV cell) chemistry does require more care to use it safely but there are lots of EV's on the road doing so. I like it much better for my use partly because it's relatively easy to measure SOC based on cell voltage. It's not deadly accurate but pretty good if you have good discharge data for your cells. This is very difficult with LiFePo4 cells because their discharge curve is much flatter. I have two carts running Leaf cells - one has been going for over four years now, the second I just built. These cells are nowhere near new condition but I can get three rounds of golf out of them and the four year old one has not degraded much through my use. I hope that by the time I need new ones there are other reasonable alternatives. I do not like any of the "drop in" or even the ones offered by the cart manufacturers. I would still prefer my "old very used" Leaf modules to any of those packages!
I built my own SOC meter based on cell voltages and the discharge curve for Leaf cells. I also have a Speedometer/Odometer that I built so that I know how far I have driven. I reset the "trip" every time I charge. I usually go about 20 miles between charges and it's at about 25% SOC then. If I had new Leaf cells, I would get much more range! |
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05-21-2021, 10:35 AM | #22 | |
Gone Wild
Join Date: Oct 2019
Posts: 646
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Re: Is RoyPow a fake company??
Quote:
For those considering or using LiFepo4, I'd suggest a shunt-based coulomb counting meter for precise SOC monitoring. You can get them in the $40-$90 range that work really well. My current LiFepo4 pack came with a voltage based meter, but really it is useless (as Volt_Ampere points out). My previous RoyPow however had a coulomb meter built into the BMS for display on the included meter. With my current pack / meter I can use the cart for 10-20 miles and charge some (I usually don't charge to 100%), use it again, charge some etc... and after a week or so I might charge back up to 100% before I use it for a longer period, and the meter (which counts up as it is charging) hits the 100% mark within 1-3 minutes of the charger shutting off. It has been very precise in my experience and I'd definitely recommend for LiFepo4. One thing I noticed however with the FET-based BMS units, is that they draw some power if the pack is set to have output at the terminals. My RoyPow would drop a bar or so every 2 days or so IIRC, and my current pack drops around 1.4% / day sitting with output "ON". I had the supplier wire a port for a simple SPST switch to control BMS output, and turning off the BMS output with that drops idle pack loss to something so low I haven't been able to measure it. The RoyPow behaved similarly, meaning if you turned off the power switch there was no (or super low) drain while not being used. That power drain isn't reflected in the SOC meter I use because the BMS is not on the load side of the shunt, but the RoyPow's configuration would, and that's why the meter would drop with the RoyPow. With my current pack, if I leave the main switch "ON" all the time, the SOC meter will get behind a little over time, and show a little more remaining than there is, and when recharging to 100% the meter will show 100% when counting back up before the charger shuts off (but when the charge is complete, the meter and battery SOC are in sync again). But by normally leaving the switch "OFF", the meter stays within 1-2% at all times. The meter I use also shows current voltage, which is nice for keeping an eye on things as well. |
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05-21-2021, 11:06 AM | #23 | |
Getting Wild
Join Date: Apr 2020
Posts: 95
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Re: Is RoyPow a fake company??
Quote:
Manufactures and their processes are young (maybe they don't really know what they're doing while "enclosing everything in a case"?), their quality assurance seems to be suspect, and some of the customer service seems to be lacking. 3 strikes in the current lithium market from my evaluation. Especially at the cost of 2x+ FLA. I'll enter the market when there is higher quality competition across the board and, hopefully, the cost of the technology reduces. |
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05-21-2021, 11:21 AM | #24 |
Gone Wild
Join Date: May 2012
Location: Rio Verde, Az
Posts: 7,125
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Re: Is RoyPow a fake company??
Coulomb counting is really the only way to do accurate SOC with Lithium - especially LiFeP04 but doing that well isn't easy either. Integrating the chopped battery current is somewhat difficult to do accurately. I have no experience with doing that myself. My odometer is as good as anything once I have experience with my batteries. My usage is fairly consistent so my range is also. If I have driven 20 miles, I know I have to charge before playing another round of golf.
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05-21-2021, 02:56 PM | #25 | |
Gone Wild
Join Date: Sep 2014
Location: Orlando, FL
Posts: 1,308
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Re: Is RoyPow a fake company??
Quote:
Note: Read the Nickmaster2 comment directly under the video. https://www.youtube.com/watch?v=Jz37WycW-7E Here is a link from a BGW member using Chevy Volt batteries, which will catch fire. https://www.buggiesgonewild.com/show...m+battery+fire |
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05-21-2021, 05:48 PM | #26 |
Gone Wild
Join Date: May 2012
Location: Rio Verde, Az
Posts: 7,125
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Re: Is RoyPow a fake company??
As long as you don't drastically overcharge or underdischarge a Leaf module, it is quite safe to use in a golf cart. Using a proper charger and BMS is required. I'm fine with that but I have lots of battery experience and I am comfortable with electronics and high current power systems. Volt cells are no more likely to catch fire than Leaf cells IMO. Both are likely to go up if you drastically overcharge them. They are a very similar chemistry.
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05-22-2021, 09:44 AM | #27 | |
Gone Wild
Join Date: Oct 2019
Posts: 646
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Re: Is RoyPow a fake company??
Quote:
I understand you've had lots of success with this type of cell and are clearly very skilled in your execution, and fully appreciate efforts have been made by the manufacturer to make them as safe as possible. I read much of the same info that you reference before making a decision. But to reiterate - it is just my opinion that older/used Leaf cells (or Volt, etc...), where the use / charge / discharge history is unknown could potentially be less-safe than new enclosed LiFepo4 cells. That's just the conclusion I felt comfortable with. I certainly don't claim to know all the answers on any subject, and fully admit as much, and appreciate being able to use the input here on the forum from so many knowledgeable contributors such as yourself to form my own opinions on various things. |
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05-22-2021, 02:24 PM | #28 | |
Gone Wild
Join Date: Sep 2014
Location: Orlando, FL
Posts: 1,308
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Re: Is RoyPow a fake company??
Quote:
I built a pack in late 2015 for a member from cells supplied by Nick and were tested at 64AH by him. About 3 months later, the member made a big mistake and went on vacation for a week leaving the KS on in the cart and the charger not plugged in. TOTAL pack voltage was down to 3.86V (.275V per cell) Talked to Nick and he had me connect a 36V standard EZGO PowerWise charger to the pack for a few minutes until the pack reached a high enough voltage for the Lithium charge to pick up and finish the charge. I had put a speedometer on his cart which maintains the total mileage driven. He now has over 2500 miles on the cart and can still drive over a mile to the course play 36 holes, come home and still have voltage to spare. The cells are still all within .020V balanced. For another member, last year I built a pack for him from the lower capacity Tech Direct cells. It was fine until he let voltage get to the point that the cart stopped running. The lithium charger was able to recover the pack but range was soon diminished (damaged the cells like the pictures attached but only small expansion of modules) to where he could not get past 18 holes on a weekend. I managed to get lucky and find him 7 modules with much lower mileage (not from TD) and his cart is fine today. My conclusion was that high quality cells could take more abuse than heavily used cells. Another member with a double pack from 2016 cells from Nick moved to coast from Orlando in late 2018 after a lot of use on street and golf course. He let his cart sit unplugged from charger for about 6-7 months, until he called me. That pack showed total voltage of .001V on a Fluke 73. In other words 0V. I tried the Nick trick and the modules could not recover they expanded fast. I had to rebuild him an entire new pack. These pictures are from that pack and the damage caused by heavier used modules and trying the Nick recovery. It didn't go well. After pulling the pack to disassemble, removing the first nut from the all thread sounded like a rifle shot and knocked the battery drill out of my hand. No fire or smoke, just puffed up like a blowfish. That is why I trust these modules not to be a fire hazard. Because of the Chevy Volt pack fire in the link earlier and of the Tesla fires all over the country, I would only build from Leaf modules. These days, any Gen2 modules found will be high mileage and far more susceptible to damage, but not fire. |
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