Just installed my new Overkill BMS and getting used to all the bells and whistles. On the home screen top left is the charge indicator. Directly under that is a an on-off switch. When I touch that switch the app posts a caution message asking if I am sure I want to LOCK the charger's FET's. Here's the deal. I use the system to support an off-grid water well pump and provide emergency backup to my house. It doesn't take much (about 4kwh a MONTH) to get what I need from the well. My 5000 watts of panels are capable of fully charging my 48V 280Ah battery in a matter of a few hours. I have actually turned the charge current DOWN to 10A on my controller/charger/inverter to avoid hammering my batteries when they are so close to fully charged all the time. I find that the gentle charge cycle keeps them balanced better and I'm not in any hurry. As my charger nears the assigned threshold of 54.4V and the cells are all bouncing around the 3.4V SOC, I hate to keep trying to cram one more watt into a virtually full and balanced battery. Typically, I've been going to the Solar Shed and turning the panels off to eliminate the charge source. It would be handier if I could disconnect charging with the app from the comfort of my house, BUT, I don't want to screw up and kill the charger or the BMS. Question: Can you safely suspend charging from the app and can you safely re-start charging from the app by simply flipping the app charging switch back and forth? Thanks for any guidance from someone using the app and a similar setup.
Charge kill switch on XiaoXiang Overkill app?
- Thread starter gnomie
- Start date
Pierre
Somewhere down South
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- Dec 21, 2019
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You can do that , no problem. I do it from time to time. You can individually turn input / output off. My units are JBD from China.
mikefitz
Solar Wizard
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Manually disabling charge or discharge BMS fets is not recomended. If for example the charge is disabled whilst there is a low current discharge taking place , the power loss across the fets could cause overheating and possible failure.
Suspending charge would be more ideal if carried out on the charger.
Suspending charge would be more ideal if carried out on the charger.
Tomthumb62
Solar Wizard
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- Sep 25, 2022
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Why not just turn the charge voltage down? 14.0v with a 13.5v float, for example. If your cells start to get out of balance due to not hitting a high enough voltage to trigger BMS balancing, then maybe 1-2x a month, up the voltage to 14.4 or 14.6v into balance is achieved.
Manually disconnecting seems like a bad idea except in emergencies, as @mikefitz points out.
Manually disconnecting seems like a bad idea except in emergencies, as @mikefitz points out.
That option is not available on the Growatt 6000 controller/charger/inverter I am using. You can turn the output off a couple of different ways but if there are live solar cells attached then it's going to provide voltage to the battery terminals. I can either (A) disconnect the panels with the master panel breaker or use the software switch in the bluetooth app to suspend charging. Other than turning the battery switch off, which also disables my inverter and shuts down the whole system, those are my options. Seems like a couple of other users have tried the software switch without any problems.
As far as I can tell, the Overkill BMS is just a tuned up JBD. Built in China but finished and calibrated in Tampa, FL.
That's good to know. I was just hesitant because of the caution message. It wouldn't make sense to include such a simple on/off option that might damage your BMS or charger but this is all pretty new to me, and I have seen a friend grenade a controller when he accidentally disconnected his battery while the controller was live on a much smaller system.
