Off-Grid DC – Beyondlogic

Review: Gatetop Low Voltage 12 – 48V DC/AC E27 Light Bulb

July 21, 2025 Craig Peacock 0

A couple of weeks ago, we reviewed the Heetech Low Voltage 12 – 85V DC/AC E27 Light Bulb. While it had a large input range of 12 to 85V, the luminous output started to dim as the voltage fell below 13.0V. If operated on a 12V battery, the reduction in light intensity was noticeable as the battery’s terminal voltage reduced throughout the night. It was also advertised and marked as 9W, but only consumed 7 to 8 watts. At that stage, it was time to try a different product and see if we could find anything better. I ordered two …

Review: USB-PD 65W Fast Charging Module (XPM52C)

July 10, 2025 Craig Peacock 3

This USB-PD (Power Delivery) Charging module is based on the XPM52C 65W USB-PD Multi-protocol Buck Converter. It allows USB devices (mobile phones, tablets, laptop computers, cameras etc) to be efficiently charged from a low voltage DC power source (8 to 30V DC) such as 12V/24V battery or power station. While my interest was in the USB-C power delivery capability, the device supports a range of legacy fast-charging protocols: This module is available from your usual cheap electronics sources such as AliExpress, Amazon, and Banggood. As the vendors normally don’t list the main part in their descriptions, search for “PD 65W …

Review: Heetech Low Voltage 12 – 85V DC/AC E27 Light Bulb

July 7, 2025 Craig Peacock 0

In off-grid systems, it can make sense to use a low voltage DC light bulb, instead of having the overheads of a DC to AC inverter – in terms of capital cost, quiescent (idle) current, conversion efficiency and risk of electrocution. For example, in a shed or other de-attached structure you could have a small 12V or 24V PV Solar system and run your lighting directly from that source. LED bulbs exist in standard E27 (Edison screw, 27mm) and B22 (Bayonet cap, 22mm) that can be powered from lower voltages – typically 12V, 24V or 48V. We review one such …

Review: Li-ion LiPo LiFePO4 Lithium Battery Active Equalizer Balancer Energy Transfer Board

August 10, 2019 Craig Peacock 31

Cheap Lithium Battery “Active Balancer” boards have been turning up on Aliexpress and other eCommerce sites. But there has been some scepticism if they are genuinely active balancing and quite a few conflicting forum posts. Some have even claimed the ‘1R0’ inductors are actually 1 ohm resistors. The more traditional passive balancer boards will simply dump any excessive charge into a resistor, wasting this energy. For example, if the maximum voltage threshold was set at 4.2V, once the cell’s terminal voltage exceeded 4.2V, any excess charge would be dumped into a resistor and dissipated as heat until the terminal voltage …

Review: BQ24650 5A MPPT Solar Controller 3S / 4S Li-Ion, LiFePO4, 12V Lead Acid

July 7, 2019 Craig Peacock 23

Designs based on the Texas Instrument’s bq24650 Synchronous Switch-Mode Battery Charge Controller for Solar Power With Maximum Power Point Tracking are commonplace on Aliexpress, ebay and Amazon. Consumers can purchase assembled PCBs, such as the one pictured above, or complete product enclosed in a relatively nice aluminium extruded housing. According to the silkscreen of versions pictured on-line, different variants are available including: 3S Li-Ion 4S Li-Ion 4S LiFePo4 12V Lead Acid I’m still old-school and wanted to purchase a 12V lead acid version, but couldn’t find any available for sale. And like many similar electronics products from the above mentioned …

Powerpole Distribution Box

February 5, 2019 Craig Peacock 2

For far too long, I have been on the search for the ideal way to distribute power for low voltage systems, typically 12V. I have an small assortment of domestic networking gear, small embedded systems, LED desk lamps, battery chargers and USB chargers that operate from a backed-up 12V PV solar supply. I have finally settled on the “Powerpole” 15-45 connector from Anderson Power Products. The 15-45 denotes that the connector comes with terminals rated from 15 to 45 Amp. The housings are designed for voltages well exceeding 100V AC or DC depending upon your choice of UL or IEC certification. …

LT8390 Synchronous Buck-Boost DC-DC Converter

January 31, 2019 Craig Peacock 17

For the past couple of years, I have been powering my Sony 55” LCD TV and charging a couple of laptop computers from a 12V solar system. Both the Sony TV and the laptop computers have an input voltage of 19.5VDC. To step up the voltage from the battery, I purchased two “LTC3780 Automatic lifting pressure constant voltage step up step down 10A 130W” a.k.a. LTC3780 – High Efficiency, Synchronous, 4-Switch Buck-Boost DC-DC Converters from ebay. These boards operated from a moderately wide 5 – 36V input and had an output voltage range of 1 – 30V. The LTC3780 has …

Review: WD2002SJ, XR-131 LTC3780 High Efficiency, Synchronous Buck Boost DC-DC Converter

July 30, 2015 Craig Peacock 0

Prevalent on ebay and Amazon is the “LTC3780 Automatic lifting pressure constant voltage step up step down 10A 130W” DC to DC Converter. (What a mouthful) I’m not quite sure what the “Automatic lifting pressure” is about (suspect Chinglish), but it is a fairly well designed DC-DC switcher based on Analog’s (formally Linear Technology) LTC3780 – High Efficiency, Synchronous, 4-Switch Buck-Boost Controller. The board sells for a bargain basement price of about $20 to $25 USD. My interest in this DC-DC switcher is to operate 19VDC laptops/notebooks and LCD TVs from 12V batteries/solar. I took the plunge and purchased two units. Here are …