I have a 13s6p Lion array with BMS I want to charge from a 12v source.

This is the Arduino Lion charger project I am attempting

After letting the smoke out of an undocumented Chinese boost converter, I was wisely directed to Mouser where I bought a GE 65W Boost Converter (8Vdc –16Vdc input; 32Vdc to 54Vdc output; 65W Output power (max.)) for the same purpose. Very compact.

Boost converter datasheet

I attached a variable pot to program it's output voltage and managed to tune it to a desirable output of 54v.

My QUESTION regards how to deal with a dramatic voltage drop to 34v when connected to the BMS. I am hesitant to adjust the voltage programming. The resistance adjustment can actually program to module to produce voltage much higher than 54v when there is no load.

Q: Is it safe to adjust it's output (that drops to 34v) back to the desired 54v output when applied to the load of my un-documented BMS?

I know the batteries can be charged at much higher current than I am using (12v at 3 amps input). For 54v, at 65w, the booster is rated for just over an amp which is within the individual battery's tolerance. It seems like it would not be enough however since I have 6 18650's in each cell.

I have ordered an inexpensive 54v charger which is yet to arrive but I would prefer to use this GE module in conjunction with an Arduino and INA219 GY-219 Bi-direction DC Current Power Supply Breakout Sensor Module.

If my boost converter can't keep up a trickle charge I don't want to waste my time.

I am unfamiliar with some of the features for which I would appreciate some clarification (indicated with (?))

Features: ▪ 8Vdc –16Vdc input ▪ 32Vdc to 54Vdc output ▪ 65W Output power (max.) ▪ Output voltage programmable from 32 to 54Vdc via external resistor ▪ Tunable LoopTM to optimize dynamic output voltage response (?) ▪ Power Good signal ▪ Output over current protection (non-latching (?)) ▪ Over temperature protection ▪ RemoteOn/Off ▪ Ability to sink and source current ▪ Support Pre-biased Output (?) ▪ Optimized for conduction-cooled applications ▪ Small size: 27.9mm x 11.4mm x 8.5mm (0.8% the size of Chinese model)

As I interpret the datasheet, the "Tunable Loop" feature is intended to handle fluctuations in current draw. I don't know if this is required to fix my problem.

  • \$\begingroup\$ What you need is a boost converter with CC/CV limit in order to charge your battery. \$\endgroup\$ – winny Jun 19 '18 at 21:25
  • \$\begingroup\$ So then my GE module in conjunction with an Arduino and INA219 GY-219 Bi-direction DC Current Power Supply Breakout Sensor Module could accomplish this task? Can I safely raise the output voltage if I did so? \$\endgroup\$ – Jean-Paul McCoy Jun 19 '18 at 21:51
  • 2
    \$\begingroup\$ "If my boost converter can't keep up a trickle charge I don't want to waste my time." You don't trickle charge Li-ion cells. So, since you don't understand how to handle your battery, you need to keep your hands off and buy a good (not cheap Chinese) charger. Do not, under any circumstance, think that you can simply buy a power supply and charge a Li-ion directly from it. One of these days you're going to let the magic smoke out of your battery. \$\endgroup\$ – WhatRoughBeast Jun 19 '18 at 22:12
  • \$\begingroup\$ Excuse my terminology failure. I meant "standard" charge opposed to "rapid" charge. I had to google the difference: "Trickle charging means charging a fully charged battery under no-load at a rate equal to its self-discharge rate, thus enabling the battery to remain at its fully charged level. A battery under continuous float voltage charging is said to be under float-charging." -not what I meant at all. My bad. Also, I am not charging them directly either. I do have a BMS and my battery's specifications for CC and CV. BTW, magic emanates from Lion cells as fire. Foot off throat please? \$\endgroup\$ – Jean-Paul McCoy Jun 20 '18 at 1:05
  • \$\begingroup\$ You need to address the voltage drop under load. And NOT by readjusting, that won't fix it. Your boost converter is going into current limit due to overload, and the voltage falls to 34V (or 2.6V/cell, telling me the battery is fully discharged. Is the converter rated for this mode of operation? What does it do under current limit conditions for a long time? Can you adjust the current limit? As "6P" means about 15Ah and you're probably getting a bit more than 1A, best case is, wait about 12 hours, watch the voltage rise to 54V, then watch the current fall to the cutoff point. Worst case: fire \$\endgroup\$ – Brian Drummond Jun 20 '18 at 13:11

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