4RExplorer
New member
I am looking into how to charge a LiFePO4 house battery from the vehicle alternator. Assumptions:
(1) The average daily electrical usage will be 300Wh, +/- 50Wh. With this usage, a 100Ah 12.8V LiFePO4 battery with 1280Wh capacity would last 4 days or so before it needs to be recharged.
(2) For cost reasons, it would be preferable to use the Toyota OEM alternator, instead of upgrading to a high output alternator.
(3) To avoid overheating the OEM alternator, the charge current will be limited to 20A or so.
Under these conditions, what battery charger works best?
Some options, with potential issues that have come up:
(1) Ctek D250SA. This multi-stage charger includes a 1st stage at 15.8V to desulfate the battery. Some LiFePO4 battery makers (e.g., the Trojan Trillium) say specifically to avoid chargers with an automatic desulfation stage, because the battery’s BMS might stop the charging at such high voltage, and charging might not resume when the charge voltage drops down to 14.8V or so.
(2) Victron Energy Buck Boost, 25A. Victron Energy released a video showing installation of a Buck Boost for charging a 200Ah Victron Energy LiFePO4 battery in a Volkswagen bus. The Help screen where they configure the Buck Boost displays a message saying that if the output current is limited (e.g. to 20A instead of the default 25A or 50A), and the house battery demands more than this limit (due to being somewhat discharged), then the voltage will not reach the programmed voltage.
(3) Balmar MC-614H. I’m told that to use this voltage regulator, the OEM alternator’s regulator should be disabled, so the starter battery will not be charged by the alternator, and the Check Battery light will always be on.
(4) Mastervolt Alpha Plus III. This device charges at 90A, so a high-output alternator would be required. The alternator may need to be modified so that it has “negative regulation”. The User Manual suggests having two V-belts to the engine.
(5) Mastervolt Mac Plus 12/12-50. This also requires the alternator have “negative regulation”.
I am not an expert, so some of the above issues might turn out to be non-issues. Which of the above chargers (or others, like the RedArc BCDC1225) would work well for charging a LiFePO4 house battery from the 4Runner’s OEM alternator? If not from the alternator, solar panels would be my 2nd choice.
(1) The average daily electrical usage will be 300Wh, +/- 50Wh. With this usage, a 100Ah 12.8V LiFePO4 battery with 1280Wh capacity would last 4 days or so before it needs to be recharged.
(2) For cost reasons, it would be preferable to use the Toyota OEM alternator, instead of upgrading to a high output alternator.
(3) To avoid overheating the OEM alternator, the charge current will be limited to 20A or so.
Under these conditions, what battery charger works best?
Some options, with potential issues that have come up:
(1) Ctek D250SA. This multi-stage charger includes a 1st stage at 15.8V to desulfate the battery. Some LiFePO4 battery makers (e.g., the Trojan Trillium) say specifically to avoid chargers with an automatic desulfation stage, because the battery’s BMS might stop the charging at such high voltage, and charging might not resume when the charge voltage drops down to 14.8V or so.
(2) Victron Energy Buck Boost, 25A. Victron Energy released a video showing installation of a Buck Boost for charging a 200Ah Victron Energy LiFePO4 battery in a Volkswagen bus. The Help screen where they configure the Buck Boost displays a message saying that if the output current is limited (e.g. to 20A instead of the default 25A or 50A), and the house battery demands more than this limit (due to being somewhat discharged), then the voltage will not reach the programmed voltage.
(3) Balmar MC-614H. I’m told that to use this voltage regulator, the OEM alternator’s regulator should be disabled, so the starter battery will not be charged by the alternator, and the Check Battery light will always be on.
(4) Mastervolt Alpha Plus III. This device charges at 90A, so a high-output alternator would be required. The alternator may need to be modified so that it has “negative regulation”. The User Manual suggests having two V-belts to the engine.
(5) Mastervolt Mac Plus 12/12-50. This also requires the alternator have “negative regulation”.
I am not an expert, so some of the above issues might turn out to be non-issues. Which of the above chargers (or others, like the RedArc BCDC1225) would work well for charging a LiFePO4 house battery from the 4Runner’s OEM alternator? If not from the alternator, solar panels would be my 2nd choice.
