Tech FAQ

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- Charging
- Sourcing
- BMS Battery Management System
- Solar
- Support

- "Waking up" battery packs
- JAG35 PCB Battery Module Starter Kit
- JAG35 PCBs
- Scooter Battery Packs
- Scooter Packs Dongles
- Charging Scooter Packs
- BMS Battery Management System

- Electric Cars
- Electric Bikes
- ES4 DIY Scooter

- 24v Ammo Can Battery


- 7S 24V PCB Battery Modules
- 14S 48V PCB Battery Modules








All rechargeable batteries have inherent risks under any circumstance. Use caution with working with lithium-ion batteries (li-ion), lithium-ion polymer (LiPo), and any rechargeable cells and  batteries. They have dangerous charging characteristics and are known to explode or burn if mishandled. Before using rechargeable batteries you should educate yourself on rechargeable batteries, especially charging, discharging, assembly, and storage. We are not responsible for any damage caused by the misuse or mishandling of rechargeable batteries.

Lithium ion batteries may explode or burn due to improper use. Using these batteries for purposes not intended by the manufacturer, including outside a battery pack and/or without a BMS, may cause severe injury and damage. We are not responsible for any injuries caused by lithium ion batteries. Use at your own risk.

To learn more about lithium batteries click here. To see videos about lithium batteries and projects, see Jehu Garcia's Youtube channel.


  • Charge batteries fully before first use.
  • Never completely discharge batteries.
  • Never over-charge batteries.
  • Do not charge unattended.
  • Do not store your li-ion batteries fully charged for an extended period of time, ie: weeks, months.
  • Only store in a case or individual box in a cool and dry place at approximately 3.6-3.7V
  • Use only high quality battery chargers.
  • Do not expose to heat.
  • Do not connect the positive contact to the negative contact without an appropriate load.
  • Never exceed the battery's specs.
  • Never try to charge or discharge li-ion batteries with battery chargers that are not made for li-ion batteries.
  • Always charge these batteries on and within fireproof material.
  • Never leave rechargeable batteries in a recharging station unattended.
  • Do not use any rechargeable battery or charger if any visible damage is present, or if known mishandling, accidental or otherwise, has occurred.
  • Always store and transport rechargeable cells in a safe, non-conductive container. Never keep a spare battery loose in a pocket, purse, etc. Always use protective cases.
  • Properly dispose of all battery cells and chargers in accordance with local laws and mandates. If unsure, contact your local municipality.
  • If a rechargeable battery overheats, hisses, or bulges, immediately quarantine the battery from any combustible materials - preferably, take the battery outside.
  • If a rechargeable battery catches fire, the FAA recommends pouring water or soda on the battery and surrounding areas - preferably, use a foam extinguisher to quell the fire.



Is it OK to leave lithium ion batteries on a charger all the time?
Nope. Don't leave lithium batteries fully charged when not in use. Discharge about halfway for storage.

How to charge lithium batteries


What is "battery balancing"?


Must lithium batteries be "balance charged"?


Where can I buy lithium batteries?
Jehu shares many great cell sources, to see them click here:

About FAKE cells
Don’t get duped into buying fake cells, which can not only underperform but can be unsafe! Jehu discusses what to look out for in this video: 




Where can I get a BMS (Battery Management System)?
Though there are many BMSs out there, to see the ones Jehu uses and recommends, click here:



Where can I buy Solar Panels?
Here are some of the ones Jehu uses and recommends:

Flexible -
Glass -



Where can I get community support?
You can find many people like you who are sharing resources and information in Jehu's various DIY communities. Check out:





"Waking up" eScooter battery packs

I have a battery pack but the BMS is in hibernation, how can I wake it up so I can discharge?

In this video Jehu shows you how to "wake up" several popular eScooter battery packs.


JAG35 PCB Battery Module Starter Kit  (+Complete)

I notice the 8s tester/alarm has 9 pins but the jumper cable has only 8 pins, will it still work for my 7s system?
The 8s tester/alarm does work with 7s, simply plug in the jumper cable starting from (-), the last pin (+) can be left out.

Connect 8s tester/alarm to 8-pin jumper cable |


What size (mm) are your standard PCB's?
The 7S PCBs and the BMS PCBs are 87mm W x 163mm L. Most of the modules have PCBs that are this same W x L (except for the small ones like the dongles).

Check out our PCB Based Products.





I want to use the sleeping scooter battery packs, but how do I make them “wake up”?

Here's how to "wake up" the scooter batteries BMS with a digital key. First you will need to get the scooter battery packs: 40 CELL NCR18650BD 18650 LITHIUM SCOOTER BATTERY PACK W/CASE

These scooter packs normally come with female connectors attached, so you will need to get the male connectors: MALE BATTERY CONNECTOR FOR SCOOTER BATTERIES OKAI ES200G or an ACTIVATING DONGLE.

These are the male battery connectors you need for your OKAI ES200G scooter battery modules to connect to the programmed Arduino that "wake up" the scooter batteries. Each battery pack needs a male connector.

Any voltage below 30v at the Discharge port is an indication that the BMS is hibernation mode. The Internal BMS can be turned on by applying voltage to the charging port (smaller cable) The battery pack will remain in the "ON" state for as long as it has a voltage of 30v or above and without a load.  Applying a load will cause the battery to shut 'OFF" after 5 seconds then remain off for 60 seconds, ON for 5 seconds, OFF for 60 seconds for an indefinite amount of cycles. Using this Arduino Controller connected to the blue cable will instruct the BMS to remain ON for an indefinite amount of time.


This MicroController is used in conjunction with the Okai ES200G scooter Battery Packs. These battery packs require a status/unlock signal to their BLUE (Tx) wire with 9600 Baud serial: 0x3A, 0x13, 0x01, 0x16, 0x79
Then the battery replies with an extensive status report on the GREEN (Rx) wire. We are currently designing a device to display the status report from the battery, but for now we can turn them on and use them to power many 36v devices.

The Arduino is pre-Programmed with the following code:

void setup() {
void loop() {
// 0x3A, 0x13, 0x01, 0x16, 0x79

To keep the battery awake you'll need 1 Arduino per scooter battery pack, or aACTIVATING DONGLE to activate x1, x2 or x4 scooter packs. For more than 4 scooter packs, you can DIY a solution to send the signal to multiple packs at once, like Jehu's prototype here: DIY Powerwall Design - PCB PowerStripIt's almost ready for production soon, so stay updated by signing up for Jehu's early access updates to be among the first to know about new products and deals:

To power your Arduino you have to use a DC-DC that makes the battery packs 42v down to at least 3.6VJehu recommends the JAG35 ACTIVATING DONGLE which includes a DC-DC, or you can buy it on it's own: DIGI-KEY STH0548S3V3.

Here's a simple diagram for reference. Jehu explains more in this video:  Okai ES200G Battery Arduino Controller - DiY Powerwall Building

In these videos Jehu explains more details on how to wake up the batteries:

These scooter packs are powerful and versatile. These instructions should get you well on your way to building your own DIY booster battery packs, emergency packs, and powerwalls.

Click here to get your 40 CELL NCR18650BD 18650 LITHIUM SCOOTER BATTERY PACK W/CASE.


I purchased some scooter batteries and I’d like to use the built in BMS if possible rather than harvesting all the cells. I only see 15.5V DC at the output port, and even when using a battery activator as you show in your videos I cannot get the batteries to wake up. I'm not getting the 36V DC I expect. Any suggestions?
Charge the battery,  use a 10s charger like this one Connect the negative pin on the small connector to the negative pin on the large connector of battery. Use the arduino controller ( ) to prevent the battery pack from turning off when you apply a load above 1 Amp.

I watched your video about adding extra battery capacity to the Bluetti AC200P with the ES200G Scooter Batteries, will this system work for the Bluetti EB 150?
Yes, you’ll just need a different connector, you'll need a DC 7.9mm x 5.5mm Male Adapter Cable, available here:

Click here to get your 40 CELL NCR18650BD 18650 LITHIUM SCOOTER BATTERY PACKS W/CASE.


For some reason my BLUETTI does not charge fast on scooter batteries. Are the scooter packs bad?
No, the scooter packs are OK. The issue is with the Bluetti settings, according to Bluetti Support. See the image below to fix this.

In the BLUETTI settings:

  1. Press DATA
  2. Then press FAULTS
  3. Press and hold CLEAR FAULTS
  4. Click YES on the pop-up icon
  5. Turn off the unit
  6. Wait 30 seconds
  7. Turn unit back on

Thx to Bryan McFalls for sharing this with our community!



What's the weight of each 40-cell scooter battery pack with aluminum case? 
Each scooter battery pack with aluminum case weighs approximately 9 lbs 2 oz. We can ship up to 2 packs in 1 box. Box dimension: 6" W x 20.5" L x 6.5" H. 2 packs with case = 18.25 lbs. Packaging will add ~1.5 lbs.

Click here to purchase the ES200G scooter battery packs without case.

How can I harvest the cells from the 40-cell scooter battery pack with aluminum case?

A table saw or a small circular saw can cut open the case, just be careful not to cut so deep that it cuts the cells. You want to go only deep enough to cut the case only. A few straight cuts all the way through on each side should suffice to separate the battery module from the aluminum casing. Better to go too shallow on the first test cut than too deep. Remember to wear eye protection. After the first cut, you'll have a good idea of the correct depth and the rest is fairly easy, just a few quick straight cuts. Several customers have decided to carefully cut them open and have done so successfully. I repeat, carefully.

To harvest the cells, Check out Jehu's step-by-step guide.

Did you know Jehu can remove the case for you? Click here to get the ES200G scooter battery packs without case.




What's the weight of each 40-cell scooter battery pack without aluminum case? 
Each scooter battery pack without aluminum case weighs approximately 6 lbs 2 oz. We can ship up to 4 packs in 1 box. Box dimension: 6" W x 20.5" L x 6.5" H. 4 packs without case = 24.5 lbs. Packaging will add ~1.5 lbs.




I got the 4x scooter battery dongle. Can I use just one or two or three packs, or do I have to connect all 4?
You can use any number of packs you like, up to the number of available connectors, of course. The dongle will do its job of feeding the digital key to keep the battery awake for any and all packs that are connected to it.

I notice the 42v 2A charger's 3-prong connector doesn't fit the XT connector on my dongle, how can I make it work?
You need to cut and strip the charger’s 3-prong cable and add an XT90/XT60 male (depending on which dongle you have) to the leads, hot & neutral (the DC side ground is on the AC). This should fit perfectly with the female XT connector on the dongle.


I bought the 1x dongle, can I just buy a few of the Okai ES200G Male Connectors and add it to the board I already have?
Yes, you should be able to add more male connectors by DIY soldering to the existing activator board with dongle. In true DIY spirit, you are fully responsible for the performance of modified dongles.


I can't insert the male connector on the Dongle into the female scooter pack connector. There seems to be no threads inside the female connector grip ring on the scooter battery for the male Dongle connector to screw into. Any suggestions?
Here's one possible solution: The female connector should only have a wide grip ring. The male connector should only have a skinny grip ring. It's possible that an extra male grip ring is threaded onto the female ring (this happens when an old male connector breaks off but leaves its skinny grip ring threaded in). The solution is very simple, just get some pliers and remove the extra skinny grip ring from the female connector and then both connectors should mate and thread on easily.


I wired two scooter packs in series with the dongles, and the voltage output is hitting around 72v, which is exactly what is expected. But as soon as I plug the series into my 72v motor controller the dongles shut off and I get no voltage. Is there something that would cause them to shut down as soon as connected to load like this?
A load above 25A will shut down the BMS on the packs, or a load above 1A on a malfunctioning dongle. If it happens immediately it’s likely a shorted controller, but if it takes 5 seconds then it could be a bad dongle.




Which charger do I need to charge the 40-cell NCR18650BD OKAI ES200G scooter packs?
You can use this 42v 2A charger:
For a faster charge, use this 36v 15A charger:

The charger's 3-prong connector doesn't fit the XT connector on my dongle, how can I make it work?
You need to cut and strip the charger’s 3-prong cable and add an XT90/XT60 male (depending on which dongle you have) to the leads, hot & neutral (the DC side ground is on the AC). This should fit perfectly with the female XT connector on the dongle.


The 36V 18A battery charger is listed as "for charging lead-acid batteries", is this OK to charge the ES200G scooter batteries?
Yes, the lead acid charger can be used to charge these packs.


Is it possible to charge 4 batteries at the same time using the 4 to 1 dongle and a higher amperage power supply?
Yes, that is how you're supposed to charge them.

 My battery pack won’t charge higher than 3.6, 3.6 and 3.7v. The dongle red light comes on, but one goes out right away. Is my pack bad?
Your pack is still good. Most of these battery packs are in hibernation mode, this means that even though the pack is resting at around 30v the output connector shows sometimes 1v to 15v. This means the MOSFETS in the BMS are off.

To use the battery you have to charge the battery pack to 42v. Once charged, some packs will automatically turn on, others will require you to bridge the negative pins on both connectors together using a jumper cable. Applying 42v to the small charging port will also take the battery out of hibernation. If you don’t have the small connector you will have to cut the original connector and solder in your own. XT60 connectors work great here.



Is it OK to leave the scooter batteries on a charger all the time, to act like a UPS (Uninterruptible Power Supply) so that it's fully or nearly fully charged all the time so it can power my devices during a power outage?

Yes. Connect the charger thru the small charging port and it will turn the FETS off at 100% SOC and it will turn on once the battery is discharged and hits a threshold.






I'm interested in purchasing the Daly 60A 24V BMS. Would I be able to program the BMS to use 6 cells in series instead of 7, and can I configure the max charge limit?
That model is locked at 7s and 60A max power both ways.




What parts do you use on your Samba?
Jehu uses and recommends these parts for his Samba conversion, click:



Do you have parts to build e-bikes?
No doubt! Some of our customers use these e-scooter batteries and e-bike wheels to make their own DIY e-bikes and to bring their old cruisers back to life. Check out Jehu's videos: 
Here are some of the things you'll need: E-Bike parts, batteries and cables
I'm interested in these wheels with motors, but am wondering if the spokes can be removed and re-laced onto a new wheel?

I purchased one of the eBike wheels with the Bafang motor and it appears that the wheel is inoperative. It does not appear to have been damaged during shipping. Is the motor bad?
Not necessarily. It's a good idea to check the motor cables first. Sometimes the color of the face wires and the phase motor wires are not the same. Here’s a picture of a combination that has worked.
Image courtesy of  Charles Newman.

I bought the eBike controller you recommended, but how do I wire it all together?

In my $150 DIY eBike video I focused on the basic function of powering your eBike, but the controller has other functional attributes.
For a complete view of its functions and how to wire them, see this unofficial video manual.


How can I fix error #32 on the ES4 kickscooter? I charged & tested voltage of all batteries, even purchased a new controller, but still need help. Any ideas?
We had 1 scooter that I can recall that had an error 32, we got the scooter working by changing the entire top stock, but we couldn't identify the specific issue, yet. Here’s some info about in on Google that could be helpful: ES4 error 32.








About charging my battery pack, do I hook up the positive and negative to the positive and negative wires of the battery so that the power flows back through the BMS circuit? If so, will that protect the battery pack from being overcharged?
Yes to both. The BMS is protecting the battery both ways, charge and discharge.





I'm interested in building a DIY Powerwall as a backup power source for my home. Do you have a step-by-step video?

Jehu has several videos showing how to build your DIY Powerwall, click:

Which would be more advantageous to build my DIY Powerwall, your regular PCB Module kits or the HP High Power kits?
The answer depends much on your own personal needs. It’s important to keep in mind that the regular PCB modules are 1C rated and the HP High Power kits are 2C rated.




I bought some 18650 modem packs and a few of the cells have 1.24v or less, are they bad cells?
Did you know that many lithium ion cells with low voltage can be revived back to normal voltage levels? Low voltage lithium ion cells are not necessarily dead or "bad", even though some chargers won't recognize them right away. Many of them can be revived by "parallel charging" between a fully charged good cell and a supposed "bad cell".

Here's how to do it:
1) Using something like alligator clips, connect the positive of the good cell to the positive of the "bad cell".
2) Then connect the negative of the good cell to the negative of the "bad cell".
3) Parallel charge for a few seconds (5-10 seconds).

That's it! This short parallel charge can increase the voltage of the supposed "bad cell" to a high enough level that chargers should be able to recognize and charge them again.


I purchased some 2600mAh modem packs to salvage the 18650 cells. I'm wondering what the specs for your High Power module boards, since it's 7s and double sided. Would each board house 5.2 ah @ 24v with my salvaged 2600mah batteries?
Yes, that's correct.




Does this kit come ready-to-use or do need to assemble it?
It comes as a parts kit and is fairly easy to assemble with standard tools.

Would this setup work with a solar panel?
It can work if the solar system will be on 24V. You can set it up with a solar panel, controller and BMS.


What do I need to make a 24V 200AH powerwall?
You would need x50 7s2p PCB Battery Modules with x700 cells (18650) 2600mA 

I've been using two 7S modules together to create a 48V pack. Unfortunately, I plugged my 29.4v charger to each BMS when the pack was in a 48V mode, resulting in a spark, now I see no voltage on my BMSs. When I check each 7S module for its 24 output, I do see 0 volts. Does it mean I blew the 5A fuse that was soldered onto the board?
Yes, most likely the 5A fuse is blown. Use a multimeter to check continuity across the fuse.



I bought your 10x Populated PCB Battery Modules to make a 48v setup, I was wondering if there’s a way to hook up a Daly 48v BMS to the packs on to the standoffs between the boards?
Yes, see the following images to see how I do it:




I'm trying to build a solar generator for an off-grid setup, using approximately 800w - 1000w, around 14 hours daily. How many 18650s would I need to be running it?
You need 14kWh, each cell is 11.80Wh, so 14000/11.8 = 1186 cells.

Here's a good place to find 18650 cells.


I recently made your 7S10P solar pack, why are we using a solar charge controller when we have a BMS controller for the pack? Doesn't the BMS already do the job?
The BMS is a smart switch. The solar charge controller is a charger. They are 2 different devices with different functions.




Who is Jehu Garcia?
VICE / Motherboard (CNET) did a short documentary about him, to see it click here:

Can I consult 1-on-1 with Jehu?
Jehu has done consulting, but the timing is not great right now, he's currently swamped with multiple projects. We’re working on indexing and compiling Jehu's content so it's easier to find and we'll be sharing that resource with you soon. Stay updated by signing for Jehu's early access updates to be among the first to know, sign up on or click here:






What is the best fuse wire?
I only use 1/8w resistor legs. They’re available here:

Why not use Super-capacitors?
Batteries work better at this time, caps are rare and expensive devices that are very good at doing things not needed for storage systems typically.

Why do some listings re-direct to Battery Hookup, BCH, etc?
When we don't have certain products in stock we redirect to our partners so you're still able to get what you need for your builds.

Do you ship internationally?
The answer is yes and no. JAG35 can ship anywhere in the contiguous 48 USA states, but is unable to directly ship internationally. We do have partners that can likely ship to you in your country. Click on our global page here:



Have a general order question?
Get your question answered by clicking > here.

Need more help?




Still need help?
Do some research and figure it out, this is DIY after all ;)