11-28-2019, 12:50 PM | #31 |
Gone Wild
Join Date: Sep 2012
Location: Charlotte, NC
Posts: 9,329
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Re: Need help with some details on this lithium conversion
I would go a different direction with the EVMS3 on a golf cart application.
Since that device is really designed for an automobile application, lets keep all of the critical control devices powered by the same +12v Battery source. You need a dedicated +12v battery to power the BMS and relays, you can get a small 12v charger and connect it in parallel with the 120VAC power. Make sure the Elcon charger +12v pin is not connected to the CAN bus cable connection. This setup will provide full HV and LV projection during traction or charging, controller lockout during charge and charger isolation during traction or other fault. Sample 12v relay with harness: https://www.amazon.com/Pack-EPAuto-R...ZRD/ref=sr_1_7Sample 120v relay: https://www.amazon.com/American-Zett...1NE/ref=sr_1_2The diodes are 1N4007 or equivalent for flyback of the DC relay coils. Edit: I will upload a new diagram later, I tried to fix the original diagram I drew using the image editor but it looks bad. The main Solenoid function is part of the Controller setup and not the concern of the BMS since the Controller needs to activate the Solenoid for pre-charge check purposes. You can use whatever Solenoid is appropriate for your Controller setup with a coil voltage matching your pack voltage. The second 12v relay is not necessary but for $3 I prefer to isolate the charger output. References to +48v are the same as Your +80v. I am moving the diagram to my Google drive so I can post a revised diagram later. Last edited by Sergio; 11-28-2019 at 04:43 PM.. Reason: Diagram label corrections |
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11-30-2019, 10:45 AM | #32 |
Gone Wild
Join Date: Sep 2012
Posts: 245
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Re: Need help with some details on this lithium conversion
Thank you all for your advice and thank you Sergio for the feedback and taking the time on the sketch. I will see if I can't go through all of this new info and sort something out finally. Thanks again
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12-07-2019, 04:31 PM | #33 |
Gone Wild
Join Date: Sep 2012
Posts: 245
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Re: Need help with some details on this lithium conversion
Sergio, if you wouldn't mind clarifying, I have a couple questions. The 120v relay that you suggested; it doesn't have a metal prong for NC and it also says 277VAC and 28VDC on it.
Is this the correct relay? (I ordered the one directly from your link, just curious if they sent the right one) There are 4 metal prongs on it but its empty where it says NC, how can I hook that up? On the 14V relay, none of the 5 prongs are identified; how do I know which ones are NC, NO, COM? Are you indicating that I need to buy the diodes and hook them to the relays? (is that the squiggly line in your drawing and is it built into the relay) What is cart power on your sketch? I see that the two 14v relays NO should go to the Pack Positive terminal. However, the COM of one goes to the Charger+ (makes sense) and the other goes to Cart Power (?). Thanks!! |
12-08-2019, 09:30 PM | #34 |
Gone Wild
Join Date: Sep 2012
Location: Charlotte, NC
Posts: 9,329
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Re: Need help with some details on this lithium conversion
Sorry, I originally found the link for the two pack of the SPDT relays and saw the link for the single unit on the page but it is for a SPST relay, this is the correct link from Amazon:
https://www.amazon.com/American-Zett...952133-0237056What are you using for you main Solenoid/Contactor, the one the Controller turns on/off? Given the higher DC voltages you are switching, it may be better off controlling the charger on the AC side as it is a lot easier to switch that load On/OFF. I am also assuming you have a small load that was being switched on/off by the Key Switch, less than 5 amps. The idea is to disconnect the hot and the switched side wires from the Key Switch and connect them to the relay K2 contacts, the key switch then gets re-wired to turn on/off the 12v signal to the BMS Key IN input. Here is another place You can order the relay and diodes from: 12v Relay SPST (K2 and K3): https://www.mouser.com/ProductDetail...YxdlOkSBp0I%3D 120VAC Relay SPDT (K1): https://www.mouser.com/ProductDetail...AENZrAmmiTg%3D Flyback Diode 1N4007 (D1 and D2): https://www.mouser.com/ProductDetail...xY3rLmCS1i8%3D You need a flyback diode in each of the DC relays controlled by the BMS (K2 and K3). Please notice that you are wiring both 12v and 120VAC to the same relays so it is important to get the wiring right the first time. The LED indicator lamps in the previous drawing are optional but can be used if You program the MPO1 and MPO2 outputs to alert of Low SOC or high Cell Temperature. |
12-09-2019, 06:54 AM | #35 |
Gone Wild
Join Date: Sep 2012
Location: Charlotte, NC
Posts: 9,329
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Re: Need help with some details on this lithium conversion
If You are not very comfortable working with this type of automatic setup, You can just do a simple manual charging switch design.
The K2 relay (and diode across its coil), the one that replaces the Key Switch is the only Relay absolutely needed. That BMS requires You tell it when it is time to charge, that is the function of the 120VAC Relay K1, but You can replace it with a manual SPDT switch wired like the contacts of the relay (no 120VAC is needed for manual charging activation). You can get a ON-OFF-ON toggle switch so one position is "Run" the other "Charge" and on the middle the system is OFF. The last relay K3 is just a redundant safety since You have a CAN bus enabled charger that turns ON/OFF by CAN commands. Make sure you notice the comment I made about not connecting the 12v CAN bus line to the charger connector. |
12-09-2019, 01:11 PM | #36 |
Gone Wild
Join Date: Sep 2012
Posts: 245
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Re: Need help with some details on this lithium conversion
Thanks Sergio, I'll get that order in for the correct relays and start dissecting what you just said lol. I started assembly in the cart so it feels like its coming together more now, even if it really isn't.
Thanks again! |
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