01-28-2020, 04:14 AM | #1 |
Gone Wild
Join Date: Jan 2016
Location: Central Florida
Posts: 295
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Question on BMS
Sergio or others. When Sergio said:
But it was December, lots of Christmas expenses and my wife often reminding me: "it is just a golf cart ", so I decided to use a cheap FET based BMS and add relays for the LV and HV setup. Does that mean that the Zevo BMS and an All trax controller will prevent HV and LV issues without rinning through external resistors? Also, who is a supplier for this BMS? |
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01-28-2020, 06:33 AM | #2 |
Gone Wild
Join Date: Jul 2018
Location: Central Ohio
Posts: 1,720
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Re: Question on BMS
The supplier is Zeva, they are out of Australia. Their website is: zeva.com.au
The Zeva BMS will prevent HV and LV issues. However, you have to add either relays or a contactor in order to have the HV/LV protection. Sergio has shared a good setup and wiring diagram for utilizing relays. Zeva offers a contactor that you can buy from them, or you can source a contactor else where. Utilizing a relay setup like Sergio has shared is much less expensive. If I can find a link to a thread where he has shared it, I'll post it here. However, I am sure someone will be along shortly and be able to share it here. |
01-28-2020, 06:55 AM | #3 |
Gone Wild
Join Date: Oct 2012
Location: Southwestern Pa.
Posts: 6,204
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Re: Question on BMS
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01-28-2020, 07:21 AM | #4 |
Gone Wild
Join Date: Sep 2012
Location: Charlotte, NC
Posts: 9,329
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Re: Question on BMS
I think BBBHC was referring to the thread when we were discussing putting the Zeva BMS to sleep to save power during stand-by.
While the diagram may look involved, the Zeva standard layout already uses two relays (LV and HV). I just added two more, one to only attach the onboard charger to the pack when the AC power is present and the other to put the Zeva to sleep when the cart is neither being driven or charged. http://www.buggiesgonewild.com/all-t...ml#post1543106 |
01-28-2020, 10:16 PM | #5 | |
Gone Wild
Join Date: Oct 2019
Posts: 646
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Re: Question on BMS
Quote:
I wonder in your setup (not Zeva) if you don't use the cart, how much current draw the BMS itself would have? I notice my controller (Navitas) draws around .07 amps, but I don't know what the actual BMS itself is drawing since it's inside the metal case of my Lifepo battery (and I don't want to go disconnecting power leads in there to insert my ammeter leads to test it). |
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01-28-2020, 10:47 PM | #6 |
Gone Wild
Join Date: Nov 2018
Location: Lady Lake, FL.
Posts: 457
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Re: Question on BMS
Both Zeva and the generic Chinese BMSs (obviously I can't speak for all of 'em) draw a very minute current while it is attached and monitoring the pack. I played with the Zeva a little and left my pack at 50% woth the BMS "Shutdown" and pack disconnected after about a month it lost around 1 volt.
On the Zeva's and the chinese BMSs I'm using the ONLY way to completely shut it off is to remove the tap wire connector from the BMS and disconnect the main pack connection. The Zeva "sleep" and even using the "Shutdown" function does not stop the BMS from having a slight drain. It's in the manual. Sent from my SM-G960U using Tapatalk |
01-29-2020, 08:08 AM | #7 | |
Gone Wild
Join Date: Oct 2019
Posts: 646
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Re: Question on BMS
Quote:
That seems like a lot, but even small draws add up when they're 24x7. It's great the LiOn chemistry has such low self discharge, but it's becoming clearer to me that the BMS and possibly controllers are what will be responsible for smaller daily drains. Guess I hadn't really considered it adding up to as much as it does. I'm curious - using the Zeva, is part of the amperage it is drawing for keeping the HV and LV solenoid coils powered? I'm probably not understanding its operation correctly but think that those coils would need to be energized to make the connections (normal operation), and a fail-safe LV condition would have to remove voltage (at least from the LV disconnect coil)? If this is the case, I'd imagine a large part of the current draw when the cart is "armed", but not in use, would be powering those coils? |
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01-29-2020, 09:01 AM | #8 |
Gone Wild
Join Date: Sep 2012
Location: Charlotte, NC
Posts: 9,329
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Re: Question on BMS
Every controller uses power when the cart is OFF, how much depends on the features and functionality provided.
If You have a cart with roll away brake then the speed sensor and all controller logic involved in detect and prevent motion are active. The Controller is always checking input pins and measuring voltage levels. The same is true for BMS, Zeva powers the CAN bus and Monitor screen, the LV & HV relays depending on design are only powered when the cart is active, but not much of a load. Putting the Zeva to sleep powers down the CAN bus and monitor which consume a good percentage of total power. If Your BMS has Bluetooth or any other type interface then it also uses power for those even when the cart is OFF. It seems like You more interested in hyper mileage at the expense of performance which is not always the motivation for people converting to lithium. I would be interested on how your drop-in pack performs in the heat of summer since it appears to have the same Chinese FET BMS or equivalent that we have discussed as potentially dropping out due to a overheated board. |
01-29-2020, 09:13 AM | #9 |
Gone Wild
Join Date: May 2012
Location: Rio Verde, Az
Posts: 7,125
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Re: Question on BMS
When I left my cart for 6 months at a time, I disconnected the BMS and the main terminals. Battery voltage was almost exactly as I left it after 6 months. I designed and built my own BMS and I designed it to draw zero current when the cart is turned off. I used a bank of small relays to connect the BMS to each cell.
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01-29-2020, 11:15 AM | #10 | |
Gone Wild
Join Date: Oct 2019
Posts: 646
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Re: Question on BMS
Quote:
Since I don't have the knowledge you do, I have to ask questions and try to learn what I can about multiple aspects in order to get to that point. I hope that neither of us has issues due to summer temperatures, but if I do (BMS or anything else inside the battery box), I'll let the group here on BGW know how warranty claims are handled by RoyPow USA. |
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