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48V electric vehicles into practical lithium battery

Wednesday on March 25th, 2020Life

This article will share electrons DIY four essential fetish: Boston lithium battery, the battery case with a needle 18650, heat shrink tubing, aluminum wire. Many DIY is not the key to success lies in how good, but the clever election materials, as well as the right solution right.

DIY advantage lithium battery electric vehicles, is half the price of the lead-acid battery, is more than five times the life of lead-acid batteries, lead-acid batteries of 1/7 by weight, particularly light lithium batteries.

Introduction: Although the car has a lot of convenience, but also to meet the needs of "face", is an essential tool for modern business. However, electric cars have many benefits, saving time, effort, and cheaper prices. Some owners of electric vehicles is not to be seen, some people really do not make very rules of the road. As long as keep the traffic rules, then the electric car is still the best means of transport.

For example, my work is six kilometers and 15 stops. Out walk from home to the bus station 10 minutes (4 minutes by bike), no traffic jams to the unit, then spent a total of 45 minutes, traffic jam going about 70 minutes. Electric cars, about 16-20 minutes to reach the destination. Cause of the traffic jam, in addition to cars, there is a big reason for my side of the traffic lights, there are several intersection red light 99 seconds. 99 seconds is not practical, because only two digits to display up to 99 seconds, 99 seconds before the still remain for 10-20 seconds, then the green light for 30 seconds.

Before we're in the red, up to about 30 seconds. This 110-120 seconds red light, what role? Many on the block wall junctions 3-5 minutes. Also been in 3-way car, a wall that is 10 minutes.

I just assembled lithium battery in 2017, because some single battery over-discharge, as long as the cause of the current ride 2 stops on the loss of electricity, already close to retirement. (Talk about the reasons behind scrapped) 2017 assembly, not making plans, this time shot down.

Lithium battery electric vehicles, mostly by spot welding, soldering or directly. However, I did not spot welder, lithium, tin eat too difficult, and heat intolerance, great difficulty welding, so 2017 I exhausted all means, spent about a month, and finally with 18650 battery box with needles successfully connected, "Boston" 5300mAh Li-ion battery, the connection is as follows:

In the figure, the left 18650 lithium battery, lithium batteries right is Boston. These two cells are the same, the same voltage, the difference is more than twice the capacity of Boston 18650, Volume 2 18650 also happens to be connected in parallel.

Boston battery is a fetish, for notebook computers, desktop computers (converted to DC power) supply available, the shield plate 4 strings + 12V + XL4015 turn the computer power supply, power perfect, DIY enthusiasts may be concerned about such a battery, is best to use currently known, the most stable, least expensive rechargeable batteries, a single cell Boston 8-10 yuan.

Section 2 + cells in series Boston protection board, plus a 5V buck boards, can be made into a charge 10600mAh Po. Etc ...... There are many applications.

Important assembly ideas, 13 string, 14 string exactly which is better?

2017 I before assembly, access to a lot of forums, most people think 48V electric car to 14 string is better, stronger.

But yesterday, I suddenly discovered a new problem, 14 string may not be good. In fact, the protective plate 14 string, 14 string charger has been on the road (like the two spent a total of 75 yuan), I regret it.

Theoretically, 13 strings better. Market finished lithium battery electric vehicles, are mostly string 13. 13 strings of power I have not tried, from the point of view voltage, and lead-acid should be about the same, the new battery within 20 km of power is also very strong.

Voltage string 13 is fully charged 4.2V 14 = 54.6V, 4 strings lead-acid battery fully charged voltage of approximately 13.6V 4 = 54.4V.

The controller brownout voltage is 48V 42V. Thus, the string 13 undervoltage protection voltage is 42V 133.23V.

If the string 14 is, undervoltage protection voltage is 42V 143V.

The higher voltage protection voltage, the more benefit the life of lithium batteries. So, the next time the assembly, I will consider 13 string, 13 string would be more beneficial for lithium batteries, because a single undervoltage protection voltage up to 3.23V.

Use absolute protection board

Later go into details, because the first one did not work with a protective plate, resulting in a lot of single battery over-discharge, direct scrapped, this has been scrapped for more than two years Section 30. Protective plate, a single over-discharge can be prevented.

The key to long life lithium battery, you must add the protective plate to protect the board's role is to prevent the single over-discharge. Try to avoid power loss, power loss occurs once, do not ride, or it may cause a single over-discharge.

Theoretical life lithium battery charge shallow shallow 1000-3000 times charge cycles, but may lead to one-off put scrap.

Lithium no memory effect, remaining power of 50?60?an be charged.

This article core: 48V electric car lithium battery pack finished

Below, this is the night spent more than 4 hours, with a hot melt adhesive of the battery case. 2 and is made, the string 14 (amount equivalent to about 48V12AH).

4.2V 14 = 58.8V, when fully charged is 58.8V.

Below, it is a rear:

48V lithium battery pack electric vehicles starting material

Below, above the black cartridge is provided with a needle 18650, requires 28; an intermediate aluminum plate is 4mm, the thickness of the card slot as an electric vehicle I is just 4mm; bottom is 1mm thick PP plate, for fixing .

1mm and 4mm aluminum composite panel board can be used with the PP. The PP plates 1mm although soft a little bit, but after pasting, excellent strength. What is PP board? Liner is the kind of student exams, but students with relatively thin.

Boston lithium look

As shown below:

Boston and other various lithium batteries, the negative electrode portion of the protrusion. Most of the conventional battery, the protrusion portion mostly positive electrode. As shown below:

Like the original electric car battery box

Below, because the bulky original box, so no, this figure is made for comparison:

Also need to purchase materials

Protection board charger. Chargers, Boston and a few batteries, use a few A. 2 and example:

13 string 13 string buy protective plate of 54.6V, 2A charger.

14 string 14 string buy protective plate of 58.8V, 2A charger.

This article has ended

In order to make this article thinking clearly, so here draw a terminator, the article so far is over.

See the aforementioned "electric vehicle 48V lithium battery pack of FIG finished" button. Key article, is the battery box 28, glued together with hot melt adhesive. Shape of the finished product, based on the position of each electric vehicle battery design.

Do not underestimate this battery box design. Such a design of the battery case, especially bother. 2017, I used the idea more than a month, finally made this double down.

Recently spent half a month idea, I would like to change the front and rear two rows, but well done. Finally, still like the original, made double down.

The remaining work is to wire bonding, these battery case 28, and is connected to 2, the string 14, and then the protective plate 14 is connected to the string.

Welding is a time-consuming work, and this battery box 18650 with a needle, not eat tin, solder multiple needs.

The battery case is expected to be finished welding, have the fastest 1.5 to 2 hours.

Annex 1: production of tools and materials

Electric iron, tin, rosin, the basic tool for welding, as shown below:

The most commonly used tool paste, hot melt adhesive. This hot melt adhesive, I thought tack strong. In fact tack is not very good, general application can be. But the shock of electric vehicles for a long time, will gradually open plastic. After a plastic, transparent glue can be used to stick instead to use. Hot melt adhesive can only deal with half a year, as follows:

Fetish 3: heat shrinkable tube

Heat shrinkable tube, about 2017 I was searched. DIY is wired in insulation artifact, if there is no heat shrink tubing, only with insulating tape, insulation tape high costs and too thick.

Usage of the heat shrinkable tube, a short cut only 1 ~ 2cm, first set in advance on the line, the weld line (until cool), the heat-shrinkable tube is moved to the position of the line, with a lighter can be blanched, heat shrink tube below, I bought variety, such as the diameter of 3mm, 4mm, 5mm are the most common:

Use heat shrink tubing as shown below (not hot before):

Annex 2: The first failure of the works

This is the end of August 2017, a first string 14 and 2 (equivalent to approximately 48V12AH power), as shown below, just the battery case being time consuming manual assembly 2 days, more time concept. No added protection board, because it was see friends say, plus a good protection board. In 1 year, basically no problem. Particularly easy to use, the first few months can ride about 20 kilometers.

If you do not add electric car lithium battery protection board, the disadvantage is that after one year, because the resistance of each string is not the same, will result in a single discharge accelerate until the release, it is easy to create a single direct scrapped, it has been two years in succession scrapped of ten or more. Was scrapped after a single section, put a new, whole battery back to normal use.

If the protective plate to prevent over-discharge, in theory, the electric car lithium battery life of 5 - 10 years.

If there is no protection board, within two years of life.

In the following figure, the middle of each cell to see a metal, with a diameter of 1.5mm aluminum wire and secured against sliding out of the battery.

Aluminum wire, but also want to share this article fetish fourth of DIY. 2016 I was in search for material, searching wire made of various metals, and she has aluminum wire. It can be used for a variety of fixed life, and with the use of wire.

Aluminum wire, two kinds of wire used was the opposite advantages and disadvantages. Aluminum wire is relatively soft, easy to fix, does not rust, but the limited strength; wire too hard, strong and rust.

The back of the figure below, I added a fuse for preventing the short circuit on a motorcycle:

In the back on the map, it is not able to see the crowded line? The improvements have been made. Since the direction of the first work, all the same cell, when so connected in series, each line will again go from top to bottom respectively, taking a total of 14 times, resulting in a trunk wire more than 70 cm.

This time, when instead the series, the series direction of the battery in accordance with the "head-tail" sequence, so that the line will be significantly reduced.

These wires, used was a square, or 1.5 square copper wire.

The non-discharge protection plate 14 string 14 string corresponding lithium battery charger:

Also consuming manual full two days, a plurality of pads 100, with the power 5V2A bare board 14, plate 14 TP4056 charging, the charging current of the current nearly monolithic TP4056 2A, TP4056 maximum originally designed to 1A. When charging, the power supply board 5V2A, TP4056 charge sheet are hot, must always blowing fan.

As shown below:

FIG backside follows:

Appendix 3: Can a multi-cell box?

18650 battery box with a needle, there are two sections, section 3, section 4, as shown below. This kit for 18650 no problems. However, the battery will not fit in Boston, the Boston battery and a period of time will naturally bulge. Therefore, the battery must be single Boston of "18650 battery with needle cassette."

Annex 4: unprotected string lithium battery charger plate 7 Memorial

The lithium battery string 7, 7 TP4056 string charger for electric scooter I, below. In this article, Du has absolutely no protection board, it must be added to promote the protection board, otherwise it will lead to a single after another scrap.

The following figure is only memorial to be abandoned works, works pretty good, right? Stand with barbecue stick to do. The 7 string charger, using 5V1A bare board, because at that time to do housework every day, on and off with a full 2 ??days Completion:

There may be a friend to ask, how I have such a variety of raw materials? Alas, much of the material required, all bought on Taobao for many years, this image was just very, very small part of my closet there are many, have the opportunity to list them.

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