08-21-2022, 04:40 AM | #11 |
Not Yet Wild
Join Date: Aug 2022
Location: Arizona
Posts: 49
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Re: Battery bms shutoff
[QUOTE=Pat911;1905179]48v will not work, it must be higher than the battery voltage to work. You most likely won’t find a waterproof one, just purchase a standard one and build it into a waterproof enclosure. This one will work.
Pat, What gauge wire would you use for the input and output wiring? Thanks! |
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08-21-2022, 09:01 AM | #12 |
Gone Wild
Join Date: Dec 2020
Location: Melbourne, Australia
Posts: 1,919
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Re: Battery bms shutoff
Pretty much anything you have lying around should be ok. Nothing too thick is required as the output will be under one amp and the input about 6 amps. Also, the cycle time will be very short. 22-20awg should do it.
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08-21-2022, 01:53 PM | #13 |
Not Yet Wild
Join Date: Aug 2022
Location: Arizona
Posts: 49
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Re: Battery bms shutoff
Pat,
Thanks big time! |
10-06-2022, 12:32 PM | #14 |
Not Yet Wild
Join Date: Aug 2022
Location: Arizona
Posts: 49
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Re: Battery bms shutoff
Thanks!
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10-08-2022, 06:50 PM | #15 |
Gone Wild
Join Date: Dec 2020
Location: Melbourne, Australia
Posts: 1,919
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Re: Battery bms shutoff
Did you build one and does it work as expected?
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10-10-2022, 12:58 PM | #16 |
Not Yet Wild
Join Date: Aug 2022
Location: Arizona
Posts: 49
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Re: Battery bms shutoff
Yes, I built one and it works great. Thanks so much for the idea! I also found out why my batteries were shutting down. There is a glitch in the firmware from the Navitas controller that monitors the battery charge level. When the batteries get to 87% charge left, Navitas thinks the batteries are drained and shuts off the power to the motor which triggers a battery shutdown. I am currently waiting for Navitas engineering to fix the bug and send me a firmware update to download! So for now, I charge the batteries when they get down to 90%. Not much range, 10% gets me about 15-20 miles of 40-45 mph driving. So far no more shutoffs.
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10-10-2022, 04:23 PM | #17 |
Gone Wild
Join Date: Dec 2020
Location: Melbourne, Australia
Posts: 1,919
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Re: Battery bms shutoff
Good to hear the concept works well. What current did you ultimately set the output to and what did you use as the input power source? Pictures would be nice too :)
Also, I believe you’re using far more than 10% of your battery if you’re getting 15-20mi. I doubt you’ll get 150-200mi on a full charge. The Navitas will be looking at battery voltage to shut off, not state of charge and SOC cannot be reliably estimated with voltage. Your SOC could be anywhere when the Navitas decides it’s time to shut down. Cheers Pat. |
10-10-2022, 06:02 PM | #18 | |
Not Yet Wild
Join Date: Aug 2022
Location: Arizona
Posts: 49
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Re: Battery bms shutoff
Quote:
Also, I believe you’re using far more than 10% of your battery if you’re getting 15-20mi. I doubt you’ll get 150-200mi on a full charge. The Navitas will be looking at battery voltage to shut off, not state of charge and SOC cannot be reliably estimated with voltage. Your SOC could be anywhere when the Navitas decides it’s time to shut down. I don't have an odometer so I am just estimating, but it is at least 10 miles for sure. Also, I am running a 432-volt system so my range is more than the usual 48v system most guys are running. I tested when the shutdown occurred three times and got the same results each time. At 88% SOC I lost 50% power and at 87% I lost all power. I talked to Navitas and they said I am not the only one. They said their engineers are working on a new firmware fix. Supposed to be this week. |
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10-10-2022, 06:03 PM | #19 |
Not Yet Wild
Join Date: Aug 2022
Location: Arizona
Posts: 49
|
Re: Battery bms shutoff
Also, I believe you’re using far more than 10% of your battery if you’re getting 15-20mi. I doubt you’ll get 150-200mi on a full charge. The Navitas will be looking at battery voltage to shut off, not state of charge and SOC cannot be reliably estimated with voltage. Your SOC could be anywhere when the Navitas decides it’s time to shut down. I don't have an odometer so I am just estimating, but it is at least 10 miles for sure. Also, I am running a 432-volt system so my range is more than the usual 48v system most guys are running. I tested when the shutdown occurred three times and got the same results each time. At 88% SOC I lost 50% power and at 87% I lost all power. I talked to Navitas and they said I am not the only one. They said their engineers are woking on a new firmware fix. Supposed to be this week.
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10-13-2022, 09:03 PM | #20 |
Gone Wild
Join Date: Apr 2017
Location: SE TN
Posts: 2,218
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Re: Battery bms shutoff
Here is the reason the charger has to be plugged in before the BMS will turn on again. The BMS will open the discharge switch if a individual battery cell falls below 2.5v. But it won't turn back on again until that cell recovers to 2.7v It happened to me yesterday. It confused me for a while because my lowest battery was setting above 2.5v.(2.637V) What I did to fix it was temporally reduce the recovery voltage to 2.55v and the BMS turned on w/o connecting a charger. This probably won't help with the store bought batteries because you don't have access to your BMS settings but it's worth mentioning. But it will work for DIY batteries.
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72v, allied, navitas |
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