03-29-2021, 06:07 PM | #31 |
Getting Wild
Join Date: Mar 2021
Location: Ancient City
Posts: 112
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Re: RXV Leaf Gen 1 to Leaf e+ Upgrade Build Thread
Very nice work. Keep looking at different cell options for my cart and circling back to the Leaf as I have to believe they are much higher quality than most of the stuff out there
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04-12-2021, 12:49 PM | #32 | ||||
Getting Wild
Join Date: Oct 2014
Posts: 102
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Re: RXV Leaf Gen 1 to Leaf e+ Upgrade Build Thread
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I’m admittedly very new to Lithium conversions on these carts so forgive me if my questions seem silly or worded incorrectly. I’m in the process of getting my BMS in place. I’m looking at the Chargery 2-16S BMS @ 600A. I’ve been in several conversations with Jason Wang at Chargery and we both seem to be a bit confused on how the 3P7S modules are configured and subsequently how the BMS ties in and functions. As I understand it there are 3 of the plates (?) tied together in parallel and this makes up a cell. Then since there are 21 of these per module there are seven sets in series. Each group of 3 should have a wire to connect to and monitor voltage, correct? So if I am thinking correctly, tying 2 of these modules together gives me a total cell count of 14 cells? I’m a bit confused on the discussion of having to use the main positive and connecting that to the BMS. What is that needed for? Would that apply to both modules or just once to pick up total voltage? If someone could sketch up a wiring diagram that would be extremely helpful. Regarding chargers, I am considering using their (Chargery) battery charger as it is adjustable for cell count, voltage, current and it communicates directly with their BMS to prevent an over voltage situation on any cell. They have a unit that can charge batteries with up to 24S and that is a programmable function hence my question above for what the total cell count would be on these. https://www.chargerystore.com/index....&product_id=62 Would this be a good solution or would I be better served to just use a “dumb” transformer based charger and use a relay/contactor to stop charging at a set point from the BMS? If the second scenario is a better solution, is it preferable to break the charger output (DC to battery) or input (AC to charger)? I plan to mount whichever charger I choose on board if that matters. Thanks for any insight/help you can offer. Sent from my iPhone using Tapatalk Pro |
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04-12-2021, 01:06 PM | #33 |
Gone Wild
Join Date: May 2012
Location: Rio Verde, Az
Posts: 7,190
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Re: RXV Leaf Gen 1 to Leaf e+ Upgrade Build Thread
These "modules" consist of 21 cells wired in 7S 3P configuration. The BMS requires 8 sense wires to measure the 7 individual cell voltages. The plug that comes out the top of these modules only has 7 wires so you need to connect an 8th wire to the positive terminal of the second module. The two modules are wired in series. You have to consult your BMS diagram for wiring.
DO NOT rely on the BMS to stop charge cycle!!! The BMS is there in case the charger fails to stop the charge for some reason. Get a charger designed to charge a 14S lithium pack. (4.2V per cell at 100%) |
04-12-2021, 08:22 PM | #34 | |
Getting Wild
Join Date: Oct 2014
Posts: 102
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RXV Leaf Gen 1 to Leaf e+ Upgrade Build Thread
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So am I understanding correctly that the 3 cells in parallel operate as 1 cell? The would seem to make sense since the BMS harness that comes out only has 7 wires. Regarding the charger, I’ve already purchased one charger that is allegedly set up as 14S and shut off voltage of 57.4V. It smoked within 2 hours of connecting it the first time so I’m Leary of buying one of these “smart” chargers that are cell count based. I can buy a dumb transformer based charger at 58.8V, but I would prefer to stop charging at 57.4V. I have my old Club Car power drive charger that is supposed to shut off at 58.8V but I’ve seen it go as high as 62V when charging my old FLA batteries. So I’m leery of buying a different transformer based charger even though they say they cut off at 58.8V. I have the cart all put back together and have taken it for a test drive and everything works, I just need to put to bed this BMS issue and charger issue. That’s why I was hoping someone would be willing to share info. FWIW this is a wiring diagram of the Chargery BMS using the older generation Leaf Cells. As you know unfortunately none of the terminals are exposed on the new Leaf cells so I guess I’ll break out the multimeter and try to figure out how to wire this in. Sent from my iPhone using Tapatalk Pro |
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04-12-2021, 08:38 PM | #35 |
Gone Wild
Join Date: May 2012
Location: Rio Verde, Az
Posts: 7,190
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Re: RXV Leaf Gen 1 to Leaf e+ Upgrade Build Thread
Yes - I had to spend time with a multimeter to figure out the wires coming out of the modules. You have to be very careful with these wires! Short one out and you are in big trouble. DO NOT use a simple transformer based charger - it won't have the necessary control on the end charge voltage. Buy a good one. Do not rely on the BMS to terminate the charge. It's not intended to do that except in the case where the charger fails.
My advice is don't fool with Lithium unless you take the time to understand exactly what you are doing. |
04-12-2021, 10:44 PM | #36 |
Getting Wild
Join Date: Dec 2011
Location: Colorado Springs, CO
Posts: 83
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Re: RXV Leaf Gen 1 to Leaf e+ Upgrade Build Thread
Yes, each pack has 7 sets of 3 cells in parallel. Your diagram of the old leaf cells still generally applies, you can see that the last bms wire references pack positive. On our packs there’s no direct access to the individual cells which is why the bms tap wires are provided. They don’t need to provide the last wire because you can use the positive terminal. Use a DVM and start to match the wires to their respective cells. As mentioned, be VERY careful. My diagram is specific to my Frankenstein bms and wouldn’t be very useful to you. Chargery’s setup is pretty good IMO, I considered it for my system and wouldn’t hesitate using it.
Sent from my iPad using Tapatalk |
04-12-2021, 10:48 PM | #37 | |
Getting Wild
Join Date: Oct 2014
Posts: 102
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Re: RXV Leaf Gen 1 to Leaf e+ Upgrade Build Thread
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I believe I got the harnesses figured out. Measuring each wire to pack negative one wire resulted in 0 volts so I assume that is B-. The remainder of the wires stepped up in 3.7V +/- increments. Measuring up between the wires one at a time resulted in 3.7V for each pair so the batteries appear to be well balanced. Sent from my iPhone using Tapatalk Pro |
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04-13-2021, 08:31 AM | #38 |
Gone Wild
Join Date: May 2012
Location: Rio Verde, Az
Posts: 7,190
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Re: RXV Leaf Gen 1 to Leaf e+ Upgrade Build Thread
Picture is too big for me to digest but that's what I did as well. The two cables I got were not the same colors or connections so I had to figure them both out. I have my cart completed - I have some pix but I have not posted them yet. I am working to calibrate my speedometer for my new tire size but I think top speed is about 25 which is plenty fast for me.
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04-14-2021, 10:25 AM | #39 |
Getting Wild
Join Date: Oct 2014
Posts: 102
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Re: RXV Leaf Gen 1 to Leaf e+ Upgrade Build Thread
Sorry about the picture size. I used the Tapatalk browser and it doesn’t allow resizing of the pictures when posting multiples at one time. It does allow resizing if posting individually
If it helps other people going through the same conversion I may repost one at a time and resize to a usable size. Thanks for your feedback so far. Sent from my iPhone using Tapatalk Pro |
04-14-2021, 11:07 AM | #40 |
Gone Wild
Join Date: May 2012
Location: Rio Verde, Az
Posts: 7,190
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Re: RXV Leaf Gen 1 to Leaf e+ Upgrade Build Thread
I always resize my pictures with Photoshop before posting or emailing them. Cameras these days generate way too many pixels for a normal 72 dot per inch display.
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