Lipo battery charging specs for mbot

#22

@chuckmcknight thanks!

#23

It’s very ironic that the latest mBot comes with a little box to hold a Lipo battery but yet there is no specifications for the battery nor a link of where to buy one. This a very bad marketing.

#24

Hi Aramperez,

Since we do not sell the battery for the mBot, You can buy any 3.7v lipo battery online or local shop and just match the size of the lipo battery box provided.
Size for the battery holder cover:

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Size for the battery holder:
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Suggested size for the lithium battery:
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#25

While these drawings help a little bit, what people need is a battery number. It’s hard to search Amazon for a Lipo battery using just dimensions, e.g. you state that for the IR remote you need a CR2025 battery.

#26

Hi,

You are looking for a 3.7 LiPo battery. The larger the mAh (milliamp hours), the longer the battery will last. I use this one from Adafruit. Amazon, Jameco, etc. all carry these. :slight_smile:

#27

Thanks for the link and information. The Adafruit link states that the battery is 51mm x 65mm x 8mm which does not appear to fit in the battery box as it exceeds the recommended size of 50mm x 35mm x 10mm. I have a hard time understanding the reasoning for including a battery box but no link to a battery that fits inside the box, but that’s just me.

#28

@ tec_support

Your suggested size of the lithium battery does not fit in the provided box. The inside measurements on your drawings are 49.2 x 32 and your suggested battery is 50 x 35. So that is too big.

#29

LiPo batteries come in several sizes depending on amount of mAh the battery supports. I would suggest spending some time at Adafruit, et al., to find a battery that fits the available space. I’ve got the 1.0 mBots, so the LiPo I mentioned just slides in under the mCore board. :slight_smile:

#30

Hi MJP,

Since the external dimensions of the battery holder is 37, the above battery size should be ok for this battery holder since we use the lithium battery with this size and it can be putted into the battery holder.
The baterries with the suggested size or smaller can be putted into the battery holder

#31

Try searching for 103550 Lipo (or 103450 Lipo) batteries.
You’ll find ones like this on AliExpress.

#32

I have found 3.7v lithium ion batteries that fit into the container provided by make block. https://www.dfrobot.com/index.php?route=product/product&product_id=437&search=lithiu

They are only 1000mAh but seemed to work well so far and are only about $9.00 each.

#33

I have bought some Lithium batteries for my 14 STEM MBOTS, but they are not charging via the USB.

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Any ideas what the problem might be? I have been attempting to charge them via a 7-port hi-speed USB Hub with the MBots switched off. When I disconnect the USB cable and switch them on, nothing happens at all. They are fully functioning with AA batteries.

Help greatly appreciated.

#34

When you plug in the USB cable with the LiPO battery attached, what happens with the charging lights?

There’s two LEDs near the JST port. On my v1 mBots these are red and green. The solid red light indicates charging. A solid green indicates a fully charged battery (as detected by the liPo charging circuit). Flashing green indicates dead/bad LiPo battery.

–andrew

#35

Thanks for your response. There is a solid red light to indicate charging. I have tried leaving them to charge for a number of hours, but when I disconnect the USB and turn on the device there is no power or lights. I have 14 of the MBOTs and 14 Lipo batteries; all with the same problem. The bots all work with AAA batteries, but we would like to avoid this, if possible.

#36

Can you use a multimeter to test that the batteries have a charge? I’ve got v1 mBots, but @tec_support said the the differences between the two was mostly adding the opaque case.

#37

Have you tried to charge only one from a different charger, I once tried to charge two from a four port hub and the hub didn’t like it. I use a bank of 2amp phone chargers with each one charging a battery via the bot, you can also get a USB tester like this one http://m.ebay.com/itm/201389370707 which will tell you what the charger is delivering.

#38

Do these batteries require a special charger?

Can they be charged using the mBot USB connector?

#39

Just thought I would summarize some of the facts about mBot, AA batteries and LiPo batteries.

  1. mBot can operate from AA batteries (4 x1.5V) or LiPo battery (1 x 3.7V).
  2. mBot needs +5V internally to operate, mBot power supplied via a TP3605 switching regulator (U1). This regulator will supply the correct voltage to mBot provided there is sufficient energy in either the AA cells or the LiPo cell. mBot will cease to operate once the under-voltage threshold of the TP3056 is reached. The mBot motors are supplied directly from the battery, not via the regulator. This means that as the batteries deplete the motor speed will decrease.
  3. mBot will not charge the AA cells connected to JP2 (barrel).
  4. mBot will charge the LiPo cell connected to P1 (JST).
  5. mBot has an onboard charger TP4056 (U2) that will charge the LiPo battery from the USB connector.
  6. The onboard charger is programmed to charge the LiPo cell at a maximum current of 1 amp. This is interesting as most USB ports will generally only supply 500mA. If you wish to charge the mBot LiPo cell in the shortest time then ensure that you use a USB source that will supply more than 1 amp. I have bricked a couple of cheap < 1 amp USB chargers!
  7. The mBot onboard charger has two LED’s just near the mBot on/off switch, a solid red one to indicate charging and a solid green one to indicate fully charged. If the green LED flashes then there is a problem with the LiPo cell.
  8. If the mBot on board charger has a > 1 amp source connected then charge time = capacity (mAh / 1000) hours. If connected to a standard USB port limited to 500mA then charge time = (mAh / 500) hours
  9. The TP4056 chip has a battery over temperature cutout but this has not been implemented by Makeblock.
  10. You may have AA cells and LiPo cell connected at the same time, mBot will deplete the AA cells first and then switch over to the LiPo cell.
  11. Measuring battery charge level using battery voltage will not provide a reliable indication of remaining capacity.

Hope this helps!

#40

Great summary @phil!

#41

More on mBot batteries:
12. The mBot on board charger (TP4056) is designed to trickle charge the LiPo battery at 130mA if the battery voltage is less than 2.9 volts. Once the battery voltage rises to above 2.9 volts the charger will switch to high current mode and charge at about 1 amp, provided the USB power source can supply 1 amp. This trickle charge rate is designed to protect a over discharged battery. If the battery is over discharged then the 130mA trickle charge can take many hours to get the battery up to 2.9 volts so that the TP4056 can safely apply the high charge current of 1 amp.
13. The mBot on board power supply (TP3605) will supply +5 volts to the mBot until the battery voltage falls to about 3.0 volts at which point the power supply will no longer provide power to the mBot. This is done to protect the LiPo battery. A 3.7 volt LiPo battery with a terminal voltage of 3.0 volts is completely discharged. Taking any more energy out of the battery may damage it.

The 3.0 volt under voltage cutoff level above has been derived from sketchy data on the internet written in Chinese. My Chinese is not good so this figure may be incorrect. I have been hunting for a TP3605 data sheet for some time now but can’t find one. If any one has a copy please post it on this forum and I will revise my summary accordingly.

Regards Phil