02-12-2019, 09:20 AM | #1 |
Gone Wild
Join Date: Jul 2018
Location: Central Ohio
Posts: 1,720
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ZEVA setup ?'s - Guru thoughts to Ian's info
I am ready to order the components to finish up my build. Due to the number of folks on this forum who have been using the Zeva system and happy with it as well as the customer service, I have decided to go with them.
I decided to email Ian before placing my order. I just wanted to make absolutely sure that I was ordering the appropriate components. Here is what I emailed him: I am building a golf cart, using 14 lithium battery modules from a Nissan Leaf. I would like to know what items I need to make this work. From what I understand, I need:BMS, gigavac contactor, hall affect sensor, temperature sensor, CAN current sensor and monitor. Is this all I need? I would like to utilize the CAN BUS. Here is Ian's reply: Our most popular option for 14-cell packs is the 8-16 cell integrated BMS. Most people also add the EVMS Monitor, for viewing operating information and doing system setup. Temperature sensor is optional, but a good idea if you are in an area that can get very hot or very cold, or expect to push the cells hard. The BMS has built-in support for a current shunt, which works fine in most applications. Probably in a golf cart you would only need a 100A or 200A shunt. Hall effect current sensors are also supported via CAN bus connection, but are generally only needed in very high current applications (500A+). You may not need to purchase an additional contactor. Normally the vehicle will already have a main contactor, and if so you can route the power going to its coil through the “LV Relay” terminals in the BMS, so that the BMS can break power to the contactor if any cells go under-voltage. You can also use the “LV Relay” output from the BMS to interrupt the key signal, the throttle signal to the motor controller, or in series with the seat switch if there is one (the switch that only allows the buggy/cart to drive if someone is sitting down). Basically it just needs to interrupt some signal wire that will prevent further driving of the cart. You will also need to set up some way for the BMS to stop the charger, using the BMS’s HV Relay outputs. (The only charger our BMS supports CAN bus integration with are the TC Chargers, but there are many other ways to integrate with other brands of chargers that don’t involve CAN bus.) Your existing charger can probably be used so long as its target voltage is suitable for the 14-cell lithium pack - probably 58V peak would be ideal. Some chargers have “enable” pins/wires you can connect the BMS signal to, otherwise you may need to wire in a power relay either on the AC input side to the charger, or the DC connection from the charger to the batteries, so the BMS can stop the charger if any cells go to high. Or, if preferred you could change to a TC Charger. Their 1.8kW model is a few hundred USD, works well, and can integrate over CAN bus with our BMS which is quite nice (allows you to adjust voltage and current output via the Monitor, view charger data while operating, and the BMS can start/stop it over CAN bus so no need for additional power relays etc). I would like to get you electrical guru's opinion on: 1. Utilizing Current shunt vs. Hall effect sensor - what is the benefit of one over the other, other than cost? 2. Shunt size - Think I read on here some where that it is not a good idea to go to big, or to small with the shunt? 3. In his third paragraph, he talks about possibly not needing to purchase another contactor. I'm assuming he is referring to the gigavac contactor. What are the thoughts with what he is suggesting there? Would this be more wear and tear on the solenoid, thus shortening it's life? Long post, sorry! Thought this was good information that everyone could benefit from. I have been looking over all the threads I can find on here dealing with the Zeva setup, and these are a few questions that I don't recall seeing information on yet. Thanks! Hope this is helpful to someone... |
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02-12-2019, 09:53 AM | #2 |
Gone Wild
Join Date: Sep 2012
Location: Charlotte, NC
Posts: 9,329
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Re: ZEVA setup ?'s - Guru thoughts to Ian's info
Here are my thoughts:
1) The major benefit of the Hall effect CAN sensor is the easy of installation and reduction of connections since You don't have to cut the negative pack cable to connect the shunt. 2) The shunt should be capable of reading the max pack discharge current, which typically is less than the Motor current so a 500 AMP shunt should be more than adequate. Also remember that you can also limit the max battery current if you have an Altrax controller. 3) I agree that You do not need the GigaVac contactor since you can use inexpensive $6 relays for LVD and HVD, here is one idea, the K1 and K2 relays are the only ones "needed", but adding K3 and K4 fully automates the entire process. http://www.buggiesgonewild.com/all-t...ml#post1543106 |
02-12-2019, 12:58 PM | #3 |
Not Yet Wild
Join Date: Jan 2016
Location: New Smyrna Beach, FL
Posts: 44
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Re: ZEVA setup ?'s - Guru thoughts to Ian's info
Interesting post. What about his suggestion of interrupting the ignition wire, etc. straight through the Zeva controller in lieu of an external relay? That combined with a CAN Bus controlled charger would eliminate the need for relays at all, right?
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02-12-2019, 01:16 PM | #4 | |
Gone Wild
Join Date: Sep 2012
Location: Charlotte, NC
Posts: 9,329
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Re: ZEVA setup ?'s - Guru thoughts to Ian's info
Quote:
You also must use a flyback diode on the external relays due to the use of Solid State relays in the Zeva. The diagram I posted interrupts the key switch power. If You add the two additional relays, the key switch is also used to automatically "wake up" the Zeva BMS. |
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02-12-2019, 03:11 PM | #5 | ||
Gone Wild
Join Date: Jul 2018
Location: Central Ohio
Posts: 1,720
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Re: ZEVA setup ?'s - Guru thoughts to Ian's info
Quote:
Quote:
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02-12-2019, 05:19 PM | #6 |
Gone Wild
Join Date: Nov 2012
Posts: 379
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Re: ZEVA setup ?'s - Guru thoughts to Ian's info
Following this, as I am about to head down the same road.
I'd like to know what shunt to buy if I am using it as hunting/off road cart. Looks like DaveTM used the 500A which Ian provided. |
02-13-2019, 07:57 AM | #7 |
Not Yet Wild
Join Date: Feb 2018
Posts: 15
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Re: ZEVA setup ?'s - Guru thoughts to Ian's info
For regen golf carts, I didn’t think interrupting the key switch would keep the motor from sending power to the batteries; hence the tow switch. Would the HV relay need to somehow be wired to the tow switch?
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02-13-2019, 08:48 AM | #8 |
Just Gone
Join Date: Sep 2015
Location: North Carolina
Posts: 3,549
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Re: ZEVA setup ?'s - Guru thoughts to Ian's info
You don't HAVE to use the Gigavac. I use a simple 48v relay that my charger is wired through as a back up just in case my charger goes over the 58.4v it supposed to terminate at. The BMS will shut the charger down if any one cell goes over the max voltage setting.
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02-13-2019, 08:59 AM | #9 |
Gone Wild
Join Date: Oct 2012
Location: Southwestern Pa.
Posts: 6,204
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Re: ZEVA setup ?'s - Guru thoughts to Ian's info
For my build I did these options:
#1--I went with the 500amp shunt. Why? Because when I connected my laptop to my Alltrax controller my cart pulled just shy of 400amps. #2--I went with inexpensive relays and flyback diodes. No need for the more expensive Gigavac relay. BTW.....I set my relays up just using two. One LV and one HV. The auto-setup works fine I'm sure, but I didn't feel it was necessary. #3--I went with an integrated CAN-Bus charger that I could control the settings. Once set, it's likely that I will never have to change that. But I like the option. (Don't buy one from China as they were clueless on the CAN-Bus setup.) #4--As for S4TA's question on the run\tow switch, someone with experience will need to answer that one. My cart doesn't have a run\tow switch or a regen option. |
02-13-2019, 09:09 AM | #10 | |
Gone Wild
Join Date: Sep 2012
Location: Charlotte, NC
Posts: 9,329
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Re: ZEVA setup ?'s - Guru thoughts to Ian's info
Quote:
It is important to properly configure the Zeva BMS when using Regen brake. The "Max Cell Voltage" should be set to the highest voltage that any cell should reach. The "Charger Maximum voltage" should be set to a value lower than "Max cell Voltage" x "Number of Cells" to allow for Regen headroom. The "Cell Balance Voltage" should be set to "Charger Maximum voltage" / "Number of Cells" (round the number UP if needed). That allows for the Zeva BMS to perform a Top Balance at the end of the charging cycle while leaving enough room to absorb Regen charge. If using an Alltrax Controller, You should also limit the "Max Battery Regen" amps to 100 amps or less. The Alltrax setting for "Max Armature Regen Brake" can still be set higher if you want more braking power. The current shunt (wired or hall effect) is really not needed unless you are planning on using the "Coulomb Count" method of keeping up SOC based on remaining AH. The "Maximum Battery Discharge Current" can be controlled by the Alltrax Controller. The EVMS Monitor is a must in my opinion as it allows You to modify and fine tune parameters after the original design. Having a CAN controlled charger is nice since it allows You to fine tune the setup but is not required, You just need to make sure you have your charger voltage pre-set to a value low enough to allow for Regen headroom. |
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