Affordable fast charging for 48v system

Announcement - Help us fight the BOTS! Please report all spam including stuff in your inbox!

orrorin6

New member
Joined
Jan 1, 2022
Messages
2
Hi everyone,

This is my first post, but I've been absorbing all the amazing information on this forum. Truly awesome.

So I have an array of 40x 48v 13S6P packs with Panasonic NCR18650BD cells that I am prepping for my camper van build. It's going to be great having ~35kWh of capacity in a van, but charging it does present a problem.

There will be about 1,200 watts of solar (so max 750 watts IRL probably) and an actual 2,000 watts coming in from the alternator (when the van is running, which is hopefully not that much.)

That's not going to be enough to keep the battery topped up, so I've been considering using a J1772 EV charger to charge the array. From what I understand, almost all (J1772) EV chargers provide single-phase 220V AC at around 30 amps, sometimes up to 50 amps. But assuming 30A EV chargers, that's 6,600 watts.

There are some expensive 48v 60A chargers out there (the highest wattage I've seen), but is there a cheaper way? I've seen some people post about 48v server power supplies and buck boost converters, but I don't know if they support CC/CV? Are there any other cheap alternatives?

For the 48v 60A charger mentioned above, I asked the vendor whether they could be used in parallel and he said they could. Does this check out? And can all chargers be used in parallel?
 

OffGridInTheCity

Active member
Joined
Dec 15, 2018
Messages
1,863
2 thoughts to share....
1) Stand-alone chargers - I use several YZPOWER 48v@15a ~ 800w chargers for my home powerwall. I have 4 of them so I can increment in 800w till I reach generator max. These are pretty well priced ($125 for 15a@48v) - here's a lithium-ion (14s) example: https://www.ebay.com/itm/283842662237
2) All-in-one units - In my trailer I use an MPP Solar 3048. It will allow up 3000w of charging thru the incoming AC input if you max it out at 25a@120v. So my suggestion is an "all-in-one" of some kind.
 

Korishan

Moderator
Joined
Jan 7, 2017
Messages
6,635
I have an array of 40x 48v 13S6P packs
Why 13s? 48V systems are generally 14s. This allows for a better voltage range to extend the length of life-cycles of the cells
13s:
13 * 4.2 = 54.6 - Fully charged to absolute max per cell
13 * 3.2 = 41.6 - Considered fully discharged (some manufacturer specs state 2.8V is fully discharged, but this puts the cells at risk of being damaged)
14s:
14 * 4.1 = 57.4 - Recommended fully charged voltage for Lithium-Ion cells (excluding LiFePO4 cells)
14 * 3.4 = 47.6 - Recommended discharged voltage for Lithium-Ion cells (excluding LiFePO4 cells)
Lead Acid:
4 * 14.5 = 58V - Fully charged lead acid batteries sit around 14.5V, and will slowly drift down to 13.5V if not charged/discharged, or 54V
4 * 11.1 = 44.4V - This is considered the "empty/dead" voltage for lead acid batteries
4 * 10.5 = 42 - This is considered extremely low, even for lead acid batteries

48v server power supplies and buck boost converters, but I don't know if they support CC/CV
Most likely no, as these are designed for Lead Acid, which doesn't need/require CC/CV

To bring around to what I asked earlier, OffGridInTheCity brings up a point with his post of the charger. It was designed for 14s, with max charge of 58V. 58 / 14 = 4.143V. This is considered within safe extended operating range of lithium ion cells.

The reason why I'm asking this is because just reducing from 4.2V to about 4.1V, you can almost quite literally add almost 1000 life-cycles to the cells. This would be likened to filling a jug up with water, but not pressurizing it to max its capacity. Do this enough times, and the bottle will split from the continued stresses. (not exactly like this, of course, but a basic generalization of what happens)

The other reason for going 14s of 13s is that you will put less amps on the cells for a given wattage. This equates to a slightly longer run time because it will take longer for the cells to reach the plateau of discharge where it just drops off (which is usually around 3.2-3.4V)
 

orrorin6

New member
Joined
Jan 1, 2022
Messages
2
Agree with @Korishan on 14s. If you stay with 13s, the YZPOWER chargers also have a 13s flavor at 15a - https://www.ebay.com/itm/283974355018

This is great, thank you!!

Why 13s? 48V systems are generally 14s. This allows for a better voltage range to extend the length of life-cycles of the cells
13s:
13 * 4.2 = 54.6 - Fully charged to absolute max per cell
13 * 3.2 = 41.6 - Considered fully discharged (some manufacturer specs state 2.8V is fully discharged, but this puts the cells at risk of being damaged)
14s:
14 * 4.1 = 57.4 - Recommended fully charged voltage for Lithium-Ion cells (excluding LiFePO4 cells)
14 * 3.4 = 47.6 - Recommended discharged voltage for Lithium-Ion cells (excluding LiFePO4 cells)
Lead Acid:
4 * 14.5 = 58V - Fully charged lead acid batteries sit around 14.5V, and will slowly drift down to 13.5V if not charged/discharged, or 54V
4 * 11.1 = 44.4V - This is considered the "empty/dead" voltage for lead acid batteries
4 * 10.5 = 42 - This is considered extremely low, even for lead acid batteries


Most likely no, as these are designed for Lead Acid, which doesn't need/require CC/CV

To bring around to what I asked earlier, OffGridInTheCity brings up a point with his post of the charger. It was designed for 14s, with max charge of 58V. 58 / 14 = 4.143V. This is considered within safe extended operating range of lithium ion cells.

The reason why I'm asking this is because just reducing from 4.2V to about 4.1V, you can almost quite literally add almost 1000 life-cycles to the cells. This would be likened to filling a jug up with water, but not pressurizing it to max its capacity. Do this enough times, and the bottle will split from the continued stresses. (not exactly like this, of course, but a basic generalization of what happens)

The other reason for going 14s of 13s is that you will put less amps on the cells for a given wattage. This equates to a slightly longer run time because it will take longer for the cells to reach the plateau of discharge where it just drops off (which is usually around 3.2-3.4V)

I completely agree, it's just that I also happen to have 20x of these 13s batteries from batteryhookup, and though I probably won't use them together now that I have these Panasonic packs, I did want to share equipment between them because they are nice batteries.
 

Solexx X

Member
Joined
Nov 16, 2017
Messages
59
I'm using this charger, https://www.fullriverbattery.com/fullriver-fr1-battery-charger/ to charge 14s 48 volt lithium Ion packs that I'm building from these, https://batteryhookup.com/products/36v-48ah-1776wh-spim08hp-36v-power-module packs. The charger has a LI setting that is accessible if you purchase the Wi-Fi dongle with the charger. It will charge CC CV at up to 20amps. It charges to 57.8 volts on the 48 volt CCCV setting. This is just for testing and bulk charging the "48 volt" batteries. I bought it so I could also charge 12/16/24/36/42/48 volt batteries by changing the settings with the Wi-Fi dongle. The WI-Fi dongle does not provide real time charging data and is just for changing the settings and viewing the last 100 charge cycle data when the charge is complete and the battery has been disconnected from the charger. You can also download the charge cycle data as a CSV file. It plugs in to a standard 120 volt outlet and I ordered it with a 50 amp Anderson plug for easy connection to my batteries. I'm happy with the performance of the charger because each 48 volt battery (5 of them made from 7 of the battery hookup 36 volt batteries) will be at the same voltage when I get the 5 BMS's completed and parallel the 5 batteries. I'll start a battery thread with photos on the build when I get some time.
Cheers!
 
Top