Li-ion battery charger suggestion

Hello,

What chargers do you suggest buying? I have one 36V battery and one 48V battery, and would like to charge them both with the same charger (they have different plugs, but that is not an issue for me).

The 36V battery charges to around 4.1V which is fine, but the 48V battery's charger charges it always to 4.2V which I don't like and would like to preserve it's life by charging it to 4.0 or 4.1V only.

I know about cycle satiator, but that is 350 euros. I've looked at ebay/aliexpress and found mostly chargers that charge only to 100% always.

Doing it right without becoming a DIY tinkerer & eBay guru costs **a lot** more money than the ignorant easy way.

Adjustability combined with reliability is very expensive, talking lab grade or industrial stuff like Sorenson, TDK/Lambda.

Satiator is actually a great compromise.

Another way to go would be to design with interchangable modular 12V blocks for bulk charging purposes, then put in series for use.

Of course I assume "high current" fast charging is required with the above comments.

If overnight plugging into mains is the use case, i.e. low amps, then just getting separate chargers or using DC converters off a common DC bus supply would cheaper than an all in one with full adjustability.

Frankly, don´t understand why you want so complicated solution. Charger for 36 V is OK for you. So you just need to wire in serial with 48 V charger general purpose 20 A diode ( for example FT2000AB, FT2000KB, FT2000AD, ….. ) to decrease final voltage .

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1 diode reduce voltage by cca 0,6 - 0,7 V, 2 diodes cca 1,2 – 1,4 V, .... Install diode on the small heat sink in small perforated plastic box. Applicable up to cca 5 A charging current.


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The diodes don't produce the same voltage drop at all currents, so they're not going to keep the voltage output the same during the charge cycle.

As the current drops, teh voltage drop becomes less, so the voltage goes up towards end of charge.

If the BMS on the battery does not shut off charge current once the voltage goes above what the battery is charged to, the battery will be overcharged. Whether that's a significant overcharge or not depends on the charger's end voltage, and the current still flowing at that point, and whether the BMS's balancing circuitry can bypass enough of the current to avoid too much overcharging.

If the BMS is working right it's not a problem...but cheap BMSs (which is almost all of what is out there in "ebike batteries") fail in all sorts of ways, all of them undetectable by the end user until something goes catastrophically wrong, such that the pack is damaged enough to make it obvious (decrease in range, pack shutoffs under load, smoke, fire, etc).


To the OP: My recommendation for a multivoltage charger is the Cycle Satiator, and make presets for each battery (and set the 36v preset as teh default)...but as you say, it isn't cheap.

My next recommendation is a lab PSU (sorenson, etc) that has adjustable voltage *and* current, with current limiting. But these aren't cheap either, and you have to make sure you set the voltage and current correctly each time you use it, because it's just knobs, with no presets.

My next recommendation is the HLG series Meanwell LED PSUs, in the -54A version, but I don't know how low the voltage will adjust. If it will go down to 42v you can use it on both packs, but you will have to adjust it every time you use it on a different pack. Eventually you'll wear out the pot, and it's sealed so you can't change it out. (the lab PSU knobs are designed to be changed a lot, but this little one isn't).

1) As the current drops, the diode temperature drops also. This in fact little bit shifts and compensates the voltage drops.

2) Charger usually stop charging at the same low current, so we can expect the same voltage drop and the same final voltage.

3) It is not important to have always absolutely the same final voltage to milivolt accuracy at the end of charging. Important is to get voltage per cell from 4,2 V down to 4,0 - 4,1 V range.

4) But it´s up to Sharkpoofie if he wants to invest 350 EUR or 10 EUR.

There seems to be an infinite number of meanwell led driver psu models, all with different specs. Here's a thread on 2 types that have a variable output range that could charge both 36 and 48v batteries.
https://www.endless-sphere.com/forums/viewtopic.php?t=92316

I have an HLG 150 watt model and its a world away in quality from the crappy chargers of old and pretty cheap too. You'll need a cheap watt meter attached to the output lead to let you know when its finished charging. There are a few complications: be careful of the accuracy of the voltage readings a lot of multi meter aren't sensitive enough to know the difference between 54.2v and 54.3v and the final voltage matters with lithium batteries. Also make sure you read the spec sheet carefully and get the right type, not all have the adjustable current and voltages. I've also read somewhere that if you pull the mains plug out and leave the battery plugged in it will drain the battery.

NickF23 said:

Also make sure you read the spec sheet carefully and get the right type, not all have the adjustable current and voltages.

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With HLG's, the A on the end means it's adjustable.

I've also read somewhere that if you pull the mains plug out and leave the battery plugged in it will drain the battery.

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True, the LED on the output does not have anything to keep a battery from powering it, so it has a tiny (few mA) drain on whatever's attached. But it's not much of a drain--it's less than most ebike controller

My trike has an HLG-600H-54A mounted to it, wired to the pack via the main cutoff switch (which also goes to the controllers). So anytime the cutoff is on, the LED is powered (along with the CA and controllers). I've left the trike switched on overnight (or longer) several times, and the 14s 40Ah pack has only dropped about half a volt (or less) from full.

A very small pack would be more affected by such a drain, but it probably wouldn't have two or three controllers plus the CA all powered by it at the same time, too.

I suspect if the HLG were the only thing connected to the pack overnight, I wouldn't see any noticeable drain of the pack (assume 10mA to power the LED; over 12 hours call it 120mAh).

So from reading here I gather my options are:

1. just buy the damn cycle satiator and be done with it
2. rabbit hole and buy led psu's with a programmable cc-cv module.

And what would be my options when I'd still like to go the diy route? getting led psu's is easy. I'd just string three 24V drivers in series and use them as the main power source. I've already built a crude programmable powersupply with a DPS3012 module and a meanwell led driver.

So my struggle is finding a programmable module where I could set the current and charging voltage.

I've only found the DPS5020 which can do 50V

DPS 8005, 80 V 5 A :

https://www.aliexpress.com/store/product/RD-DPS8005-programmable-constant-voltage-current-Step-down-power-supply-module-Voltmeter-Ammeter-buck-converter-80V/923042_32849962454.html?spm=2114.12010108.1000023.60.72477d70EosJFN

How the f*** did I oversee the dps8005 ? thank you very much docware!

Both Satiator and Mean Well are basically straightforward.

You have no idea the possible rabbitholes awaiting you so many alternatives, become an expert you can get everything you want for $30 but hundreds of hours' learning, including learn to solder, maybe have custom PCBs or 3D parts made to your design

Sharkpoofie said:

So my struggle is finding a programmable module where I could set the current and charging voltage.

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As stated, quality industrial PSUs that will do exactly what you want can easily be found, Sorenson, the various TDK buyouts Nemic, Lambda, maybe Samlex.

But $4-600 would be a bargain for a good one, even 10-15 years old. They do sometimes show up on eBay, but again, that can be a rabbithole in itself.

Maybe cheap Chinese, but risky that.

Cheaper to buy fixed voltage / amps, one per target bank.

Sharkpoofie said:

How the f*** did I oversee the dps8005 ? thank you very much docware!

Click to expand...

Looks nice on paper. Current high enough?

Cheap enough you can keep spares!

Yes, the current range needed is a critical factor in cost.

I am an outlier in that say 1-2kW is for me a small to medium unit. . .

I use this power supply:
https://www.ebay.com/itm/5A-60V-Lab-Adjustable-DC-Power-Supply-Line-Variable-Digital-Voltage/202347860740?hash=item2f1cdf5304:g:sjoAAOSwwTFcE134
It works great for all my packs. I usually set maximum volage to 4.15v/cell when I charge....cant do that easily with purpose-built 36v or 48v battery chargers.

PS: Dont short output wires when set to higher-voltage >1amp....I blew out pair of primary push-pull MSFETS, fuse, thermal-resistor, capacitor, and final regulated stage MSFET. It is fixed now just like new.

Great find!

Newegg sells them https://www.google.com/amp/s/m.newegg.com/amp/products/297-006V-00041

prolly means something.

Man, no wonder China's taking over the material world

Another approach

Get a PSU at a bit lower fixed voltage than the lowest you need, then

lots of cheap-Chinese adjustable DCDC boost converter boards, supposedly rated for 1200W, go up to 60V output

probably good for 300W continuous, maybe 600W with a fan.

Drok has a decent rep. . .

https://youtu.be/0Z5QWzSSvdI

Sharkpoofie said:

[*]rabbit hole and buy led psu's with a programmable cc-cv module.

Click to expand...

Don't need anything but the LED PSUs as long as you get the versions that are adjustable voltage and current. (like HLG-xxx-xxA) They're already CC (at whatever you set the current to), and will be CV at the end (at whatever you set the voltage to).

I've come across a mean well charger ESC-120-54.

On a local site it costs 70 euros and it's a adjustable voltage battery charger with battery under/over voltage and polarity protections(ESC models only).

What do you guys think of this as a battery charger? Seems quite nice for the price. Quite compact too. And when paired with a dc amp/volt/energy meter (this one for example) it would be a nice combo for charging batteries at home.

Spec sheet: ESP-120-spec.pdf
Product page: ESC-120-54

highlights:

• adjustable voltage 48-56V
• ESC-120 has 2A output and ESC-240 4A output
• under and over voltage protection - ESC model only
• polarity protection - ESC model only
• the ESC-120 models are fanless

I've found that meam well does make battery chargers, link to my post

So I'd probably go this route if it has everything I need

I don't see how it decides how long to hold Absorb / CV stage before dropping from Absorb to Float.

In other words, "deciding" the battery is full, to avoid overcharging.

If it does not have any such "intelligence", then it's just a power supply, should not IMO be called a battery charger.

Scheduled to be obsoleted, to replaced by ??

Con's, compared to HLG series:

216W is enough for you?

Not designed for resistance to weather/corrosion, vibration / shock.

Requires a fan for cooling.

Isolated output? Can be series'd and/or paralleled?

Since datasheet silent, believe means no. . .

So you'd get one for 48V, and use something else to step that down for the 36V pack?

What kind and type of battery are these and how big ?

Sharkpoofie said:

I've found that meam well does make battery chargers, link to my post

Click to expand...

It's not adjustable, so it doesn't do what you want. It's just a fixed power supply. Doesnt' even come in a voltage that would work on your 36v pack.