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Running the XTR Di2 system on 6 V
- Thread starter HDMW
- Start date
What happens when you try it? (shouldn't hurt anything).
It may be more important for the current capability of the 6v source to be high enough, than the voltage to be perfectly correct.
It may be more important for the current capability of the 6v source to be high enough, than the voltage to be perfectly correct.
Hello Amberwolf (interesting name):
I'm in the process of ordering a new trike. I don't have the equipment at the moment.
I've asked Shimano but I don't expect an intelligent answer. I expect they don't like the lower orders modifying their equipment.
The battery for the XTR Di2 is small, like a pen light and could be hidden in the handle bar. Also, there's a container which can be fixed to the frame. However, drawing power from a single source for lights, derailleurs and motor is more elegant.
An acquaintance remarked 7,4 v is an odd number for electronics. He suggested the 7,4 v is down to three lithium ion cells. If that's the case then two might not have been quite enough and the electronics might have a way to reduce the 7,4 to say 5v which is more normal.
Your advice is likely the only way to find out, namely, try it.
Regards : Hubert Wagner
France
PS : I've been riding trikes for years and every year I look for ways to electrify. Until now I've not found a setup I thought sensible and this has nothing to do with price except indirectly. There are plenty of good trikes but here in Europe most of the motors are down right silly. The costs are outrageous and the performance is restricted to 25kph. Worse, at least one outstanding hub motor turns into generator over that speed so this adds to the drag. This of course is the price one pays for living in a communist collective.
I might add for years I've been dreaming of a solution without derailleurs.
Yet, now I believe I've found the ideal setup. A trike with Heinzmann hub drive which can be tuned to a sensible speed by the supplier (unlike all the others). Shimano Di2 front and rear derailleurs with full synchronization. Shifting is so refined on might as well an IGH running like a Swiss watch. And the price is sensible.
I'm in the process of ordering a new trike. I don't have the equipment at the moment.
I've asked Shimano but I don't expect an intelligent answer. I expect they don't like the lower orders modifying their equipment.
The battery for the XTR Di2 is small, like a pen light and could be hidden in the handle bar. Also, there's a container which can be fixed to the frame. However, drawing power from a single source for lights, derailleurs and motor is more elegant.
An acquaintance remarked 7,4 v is an odd number for electronics. He suggested the 7,4 v is down to three lithium ion cells. If that's the case then two might not have been quite enough and the electronics might have a way to reduce the 7,4 to say 5v which is more normal.
Your advice is likely the only way to find out, namely, try it.
Regards : Hubert Wagner
France
PS : I've been riding trikes for years and every year I look for ways to electrify. Until now I've not found a setup I thought sensible and this has nothing to do with price except indirectly. There are plenty of good trikes but here in Europe most of the motors are down right silly. The costs are outrageous and the performance is restricted to 25kph. Worse, at least one outstanding hub motor turns into generator over that speed so this adds to the drag. This of course is the price one pays for living in a communist collective.
I might add for years I've been dreaming of a solution without derailleurs.
Yet, now I believe I've found the ideal setup. A trike with Heinzmann hub drive which can be tuned to a sensible speed by the supplier (unlike all the others). Shimano Di2 front and rear derailleurs with full synchronization. Shifting is so refined on might as well an IGH running like a Swiss watch. And the price is sensible.
HDMW said:
Dunno how it could be 3 lithium ion cells--that would put each one at a median voltage of 2.4v, which is in the kill-the-cell-overdischarged range--and since the 7.4v is going to be the *middle* of the range, it'd damage the cells at the bottom end of it every time you used it (with a small risk of fire upon recharge, growing with each cycle). Well, probably not for LiFePO4 with it's 2.8v median vs 3.7v, but I doubt they're using that chemistry; it's just overwhelmingly more common for LiCo, LiMn, or some other higher voltage (3.6-3.7v) flavor to be used for a variety of reasons.
7.4v is about 6 NiCd or NiMH or SLA cells, or 2 lithium rechargeable cells, at their average voltage. If it's lithium, then at minimum voltage of around 3v/cell that's 6v just before you have to recharge them, and at full charge of around 4.2v that's 8.4v max at full charge.
So at a guess, as long as it can supply the necessary current, the 6v would probably work--but if the shifter electronics are designed to stop working (LVC) at a voltage higher than that (to protect the cells) then it wouldn't work. Or if the 6v is just right at the edge of that LVC, it would work fine most of the time, then sometimes just not work, if the 6v was not well-regulated, and sometimes dropped a bit low.
If they're using a common buck regulator like a 780x to get that down to 3.3v, for an MCU or other control logic, then using the full voltage for the shifting motors themselves (or even the regulated voltage), then 6v would probably work fine. Unlikely to be a 7805 for 5v as taht should have 7.5v minimum input. But it could be any number of possible voltage conversion methods / chips, so you can't really tell without trying it. :/
I've never found anything (in any technology section) that does what I want, so always end up either making my own or modifying what I do get so heavily that when I'm done it'd've been easier to start from scratch if I could have. :lol:
That's how I ended up with the SB Cruiser as it is now, though it's still a ways from being ideal. Probably gonna need a few more major revisions before I get there. :lol:
Did anyone have any success with this?
I have a Bafang mid-drive motor with a 6V out and would rather use it than an additional battery.
I gave it a try and the A Junction did not light up for me.
Anyone tried to run 12V through it? Would that fry the electronics?
I have a Bafang mid-drive motor with a 6V out and would rather use it than an additional battery.
I gave it a try and the A Junction did not light up for me.
Anyone tried to run 12V through it? Would that fry the electronics?
