I went out to charge my batteries today. I have 200AH Battleborns The Victron app said there was a low voltage alert, but the state of charge was 100%. This was wrong; it was really about 20%, based on it being at 12.9 volts. I connected shore power -15 amps - and the Victron app showed 10 amps. This slowly dwindled down to 3.5 amps over an hour. It's been charging for 7 hours and I only went from 20% to 39%. I disconnected shore power and reconnected, and it went back to 10 amps, but it's already down to 7 amps after 10 minutes. The batteries are nowhere near charged enough to warrant such a slow charge.
Why is it taking so long? Why isn't it charging at 10-15 amps consistently? Why would the state of charge show 100% in the app, but also show a low voltage alert? Why would I even get a low voltage alert when lithium batteries can be depleted to 0? Why would my solar controller stop charging upon a firmware update (it suddenly showed only 17.5 volts despite being in direct sun, no issues with loose wires, and Victron won't turn the charger on unless the voltage is +5 VDC over the battery voltage, which is about 13.
I can't find any good answers to these questions online.
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2013 CS-S us@gi
2015 Toyota Tacoma PreRunner Double Cab
https://tab-rv.vanillacommunity.com/discussion/16210/wfco-wf-8735-ad-lifepo4-fyi-on-annoying-auto-detect-quirk/p1
If you want to post screen shots of your solar controller settings page, we could help you ensure the settings are correct for lithium.
2023 Tab 400 / 2022 F150 XLT Sport 3.5EB
Traded in - 2018 T@B 320 S/2019 Toyota 4Runner SR5
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Beyond that, some of what you are describing may be associated with the Battle Born BMS "low voltage disconnect," which is described by Battle Born below. I am suggesting this, mainly because your Victron displayed a "low voltage" alert, plus you wrote that the SoC is 20%. Maybe try disconnecting the battery from the WFCO power center and charge the battery with a stand-alone lithium capable battery charger (at least partially) to get it out of that "low voltage disconnect" state:
"Sometimes, after fully discharging a Battle Born battery, a user won’t be able to get any more power out of the battery, even after charging it. To troubleshoot batteries, measure the battery’s voltage. A voltmeter will register a low voltage of between 0V to 5V, or maybe a little higher. It may seem like the battery is malfunctioning, or damaged, but actually, the battery has gone into low voltage disconnect. In this mode, the internal Battery Management System (BMS) is protecting the battery from falling below 10V and won’t allow a charge to be drawn from the battery, even to a voltmeter. To get a battery out of low voltage disconnect mode, simply take the battery out of the system, connect it to another 12V source for about 5 to 10 minutes. This process is similar to jumping a dead car battery and will “awaken” the battery. After the battery receives a charge in this way, it should register above 10V and will be able to accept a charge from your normal charger."
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Finally, here's an interesting article that showed up in my inbox today, regarding why voltage is not a reliable indicator for a lithium battery's state of charge. It provides helpful info for anyone interested in the topic:
Why Voltage Isn't a Reliable Indicator for Lithium Battery State of Charge - Camper Smarts
(Alde: 3020; Refrig: Isotherm Cruise 65 Eleg; Battery: BB 100Ah LiFePo4; Solar: Renogy 100Ah Suitcase; Victron BMV-712; Pwr Cntr: PD-4135KW2B; EMS: PI-HW30C)
Greg & Marlene (Tucson, AZ)
(Alde: 3020; Refrig: Isotherm Cruise 65 Eleg; Battery: BB 100Ah LiFePo4; Solar: Renogy 100Ah Suitcase; Victron BMV-712; Pwr Cntr: PD-4135KW2B; EMS: PI-HW30C)
Greg & Marlene (Tucson, AZ)
Another disappointment is how little wattage the solar panel produces. In perfect conditions it is maxing out around 19 volts, or 60 watts. It's a brand new panel, and the original one would generate close to 100 watts before it dies on me. This is my third panel.
Regarding the solar panel. Are you talking about the panel that came installed on your Tab?
Ken / 2023 Tab 400 “La Bolita” (23,000+ miles) / 2024 Toyota Sequoia
2024 - 3 Trips - 35 nights - 9 National Parks, 3 National Forests