So I bought the Victron MPPT 75/15 and a BP 12/24 low voltage disconnect for my Father-in-laws camper I want to know the best settings to keep his Lead acid batteries working the best. So I am thinking the undervoltage cut off on the auto disconnect should be 10.5 V to keep them working best. I want 11 but the lowest is 11.25 then next step is 10.5. Suggestions?
Best voltage ranges for Lead Acid
- Thread starter naelr
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gnubie
Solar Wizard
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- Sep 20, 2019
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10.5 is not working the best. Drawing down to 10.5v, idle, is in fact totally flat. It you want your LA battery to last only take it down to 12.2 volts, idle
idle being the voltage on the terminals when there is no load and no charge being applied for a few hours. I'm not completely aware of how the BP works, it would pay attention to the load to determine the real battery voltage but I can't say exactly how it should be set up. 11.25 sounds like what you want.
idle being the voltage on the terminals when there is no load and no charge being applied for a few hours. I'm not completely aware of how the BP works, it would pay attention to the load to determine the real battery voltage but I can't say exactly how it should be set up. 11.25 sounds like what you want.
See I installed a manual disconnect because he keeps leaving his camper for a few days and the batteries will be discharged to like 8 volts. I have yet to find the phantom load that is taking them that low. He keeps "forgetting" to turn that dial. So this will cut off the batteries before they get damaged. He has replaced 3 now and won't listen and just get some LiFePO4 drop in replacement. With that setting 11.25V will be the cut off but the device will not turn back on until batteries get to 13.25V. That seems like quite a spread to me.
Getyourbone
Hard to offend but hard to bend...
The bigger the load, the more trouble you are going to have with tripping the BP due to sag...voltage drop due to internal resistance of the battery.
Rider
Solar Addict
Being lead acid, you really don't want to drop below 50%, ie 12.2VDC should be your minimum. Anything lower and you risk shortening the battery life.
I think I am going to leave it at default ... 10.5 cut off and 12 turn back on and see what happens... yea I get you .. he has a 5th wheel and most of the time it is plugged into shore power but I suspect the problem is in the inverter that powers the residential refrigerator. Even when it is off something is still drawing power. His problem is when he is not there not when he is.
Getyourbone
Hard to offend but hard to bend...
Stick a decent trickle charger on it and call it good?
Can't really do that when your camping and there is no power to connect too. That is why I bought the Victron MPPT 75/15 like I said. But I am conserned on the low side at night when there is no sun.
Getyourbone
Hard to offend but hard to bend...
?
Sorry I I have been a little more descriptive… Meant solar one... Solar battery maintainer.
Sorry I I have been a little more descriptive… Meant solar one... Solar battery maintainer.
Amazon.com: SUNAPEX Waterproof 25W 12V Solar Battery Charger & Maintainer Pro - Intelligent and efficient Charging Controller - Portable Solar Panel Trickle Charging Kit for Car RV Marine Boat Truck: Garden & Outdoor
Amazon.com: SUNAPEX Waterproof 25W 12V Solar Battery Charger & Maintainer Pro - Intelligent and efficient Charging Controller - Portable Solar Panel Trickle Charging Kit for Car RV Marine Boat Truck: Garden & Outdoor
www.amazon.com
OH I see no I want to put some panels on the roof. Have this guy coming and going to play with it on the victron MPPT which has already arrived.
so if I put it on the roof it should have at least 50W of some kind of usable sun some time through the day and hopefully keep the battery from dying.
I'm not understanding the 50% part. Is there a section here to learn more about these discharge optimal settings? I have 2 FLD Trojan 6V T-105 Deep Cycles hooked in series for 12V. They are connected to a HQST 30A PWM Solar Charge Controller. Its default Over-discharge Return Voltage setting is 12.6V and the default Over-discharge Voltage setting is 11V. Not sure if these are optimal?? The Solar Panel is HQST-100P (which came in crossed out Renogy box, heh).
My objective is to connect my other 2 FLD battiers in series with the others for 24V once I purchase a second panel to hook in series for 24V. But, I need to better understand the percent stuff and which settings are best for the charge controller with the current setup and with the expanded one once I can. Any direction/help is appreciated. Links provided are to the manuals and Amazon link for panel.
Rider
Solar Addict
Yes. There is a whole section in the forum on Learning.
Battery FAQ
If you have a battery question and it's not a "beginner" question please try one of the battery boards. Batteries play an important role in solar PV systems providing power while the sun is down or during peak demand hours with excess grid charges. During the day solar energy is converted by...
www.diysolarforum.com
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