Also I would like to point out that it seems to be one of the few places on the internet that is still has rather positive vibes to it. Users make jokes and exchange ideas and more importantly you're not shot down immediately for having an opinion on a subject.
It's a great way to have a chat for quick questions like flashing etc without the need of opening a thread on the forum. However for some cases a permanent thread is required for more serious question, like the one I have for you today.
Let's get to the point
I got a pretty sweet deal on an ES1 last November but I soon realised that with my 7'0, 270 pound frame it needed a little extra juice, so I went ahead and installed an external battery, one of those official ones from Segway (not a DIY pack like some do with the 365's)
All was good until my girlfriend complained about the ext battery getting lose halfway through the ride, sometimes giving error 42 etc etc and she also asked if I could put lights underneath it like on the ES2. Now you guys need to know that I'm a vivid DIY'er with good knowledge of EV's (I did make my own e-bike after all).
First I thought about just putting 3x 18650 cells in the decking that would power 2 LED strips at the bottom. This would mean next to no risk of messing anything up with the internals). Then it occurred to me that since the connection between ext battery and scooter was failing anyway, I might as well open it up and have a look at that connector and test for continuity. After some struggling I got her apart and couldn't see anything suspicious so I continued working with the lights.
As I continued to disassemble the scooter I noticed this huge space in the bottom board underneath where your feet would be. The cavity measures 170mm across, 30mm tall and ± 4200mm in length so that would be perfect for for putting 20x 18650 cells + BMS!!
So one evening and a couple of beers later I got the ext battery cracked open and decided to switch it off before attempting to cut loose the individual cells and short something out. THIS was probably the mistake I made: I held down the button on the ext batt board to switch it off).
Skip forward a day and I got all the cells lined up in a row of 20, BMS connected on top of the cells and with 37.2v to the leads. Perfect right? Well upon hooking the ext battery up, bam, error 42
First I thought I messed up the polarity of the C-, C+, RX and TX pins (you know how the ext batt connects with 2 big power pins and 4 smaller ones, well the smaller ones are labelled C-, C+, RX and TX. (Charging and I suppose data transfer between control board and batt through RX and TX).
In the end the polarity was good, I made the wires shorter in case the RX and TX signals weren't strong enough to cover 2 feet of wire (
). I even hooked up that little circuit board of the ext batt that lights up 4 LED's according to the SOC.Well nothing seems to do the trick on the hardware end so I suspect something is failing me on the software end. Which is why I'm writing this (arguably too long) post.
I think I accidentally reset the ext batt when I held the button on the BMS down. So now the whole system is freaking out and it can't communicate any longer between the two..
When I first hooked up the ext battery when I got it, the scooter went beeping (can't remember the err code) but an FW update was prompted to the app. After this the two could communicate perfectly.
This didn't happen again not even after flashing older OFW versions onto the controller.
This leaves me with a couple of scenarios, some better than others:
#1: someone on here is my knight in shining armour and know how to flash the ext batt BMS (0.5% this will happen).
#2: buy a 10s BMS of the internet and hook that up to the controller. Two options to do that:
----hook it up in parallel with the int batt to effectively increase the capacity (of course making sure the voltages are the same to prevent one
charging the next. Problem with this is I'll have 2 charging ports (so you have to remember switching the charger over when one is full. And also
the capacity might not be the same of the int batt and the ext batt which will be catastrophic when one is already near 30v and the other still
has 36v in it.
----hook it up just like the ext battery is but skip the charging and data connections. This probably wont work as the err 42 still persists if I
connect
the current BMS with just the power leads. The controller probably detects a voltage across something and then proceeds to check it for
communication.
#3 organise the ext batt cells so that they have more or less the same capacity per 2 cells (I got a cell capacity tester here so that is not problem to
do). Then run 10 balancing leads from the internal batt BMS through the tube, through the front suspension and into the deck. Hook those leads
up to their respective pair. This will convert the int battery from a 10s2p pack to a 10s4p pack. At least now I got the range back that I now lack.
Problems: well the obvious, having 10 cables running down the tube and especially through the narrow suspension hole aint going to be easy.
With option 2 and 3 I will still miss the power boost that I desperately need. CFW might have the answer to this by simply adding more top speed and more torque but legitimate sources (one of which are the great guys at Banana Science) have pointed out that they could never reach the power boost provided by an ext batt with simply flashing CFW.
Rad606 on Discord had a good shout: "Someone here mentioned that you could get the power boost that you get from an external battery by connecting the internal battery to both inputs. I have not had it confirmed though."
This could indeed work although as I'm writing this I realise that this will most likely have the same problems as my #2 solution: controller detects a voltage and then tries to communicate which will lead to an err 42.
As you can see I am in quite a predicament here and am stuck in the mud.
What are your guys takes on this matter? What would you do if you were in my situation?
If you made it this far, thank you for taking the time to read half a book.
Bob
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