Dual Charger Setup with 3 charging options

[Tinkererboi]

First i would like to thank @Seba for giving me the idea and sharing his knowledge without which I would not have thought of this project. 

Check out his thread first:

 

Decided not to go this route after the news of adjustable chargers going rogue and killing several 16x wheels with 100v++ despite being set to 84v.

Felt more comfortable using my tested and proven GT16 chargers which are decently fast and never get hot. You can use any charger for this mod, just install the right connectors for your adapter/meter.

For those who might attempt this: Mains voltage is dangerous, even more so when combined with mislabelled chinese components. My GT16 pinouts were completely reversed despite what the sticker read, and the Lenovo plug was wired backwards from what is used on the KS-16x. CHECK ALL POLARITIES WITH A MULTIMETER!

Do not recommend the first half of this project for the inexperienced DIYers. It's much more worth it safety wise to just buy a chargedoctor off ebay or a ready-made meter/adapter from a trustworthy source. So much could have gone wrong

Parts used:

Lenovo male cable for 16x
https://s.click.aliexpress.com/e/SGpXCDJXH

GX16-3 female socket for GT16 chargers
https://s.click.aliexpress.com/e/dz4VdU8Rt

Coulometer
https://s.click.aliexpress.com/e/qh7dWjVcX

GT16 Charger (or whatever you like)

This setup gives me 3 options:

5.5a fast charge, 84v, 100%

2.7a slow charge, 82v, 90%

2.7a slow charge, 84v, 100% 

I forgot to document the assembly of my coulometer as the mislabelled markings were pissing me off and giving me a headache.

The next part onwards is relatively safe and easy to attempt.

The GT16 charger has only one tamper-resistant triangle screw hidden under a sticker

Trimpot was hidden under a glob of silicone probably to prevent tampering as well. Peel it off carefully. The dial is fragile and can be yanked off easily. Keep a close eye on the meter and turn very slowly and gently until you reach your intended voltage. 

My charger only had one trimpot which makes things simpler. However, note that many chargers have 3 according to Seba. Check his thread to make sure you do not adjust the wrong one if you have one of those.

82.5v: close enough for me.

Put everything back together and its done!

Now I can charge to 90% - my daily use option, or 100% for balancing once a month, or fast charge at 5.5A which is always nice to have when in a hurry.

[EUC Custom Power-Pads]

I don't get it. 

How can one charge with 5.5A if the charger only has 3A? 

How do you switch between 82.5 and 84V? I hope you don't turn the potentiometer all the time?

[Tinkererboi]

Whoops, did not realize the context was lost with this picture missing thanks to only being able to upload 3mb per post:

@buell47 my setup allows 2 chargers to be used at once in a single port just like the chargedoctor for 2.75A+2.75A=5.5A. Normally I only use one charger (82.5v) at a time if i'm not in a hurry. 

If i only want to balance the battery pack, I use one 84v charger (2.75A)

If i want fast charging, i plug in both chargers at once and get about 84v 5.5A.

Actually there is a fourth option, and that is to plug my adapter into one port (5.5A monitored) and the stock Kingsong in another port (1.5A unmonitored). This gives a combined 7A fast charge. However i do not use that as I like to log all my charges with the coulometer.

Thought i would like to share this as it may be an alternative to having an adjustable charger especially since most of us already have a ton of chargers sitting around. This also allows one setup to be used for all your wheels instead of having to swap between the huge pile of chargers in your charging corner.

Theoretically one could build their adapter to accept as many chargers as they want at once with and even get 20A, but the thought of putting that much stress on the battery makes me shudder.

[EUC Custom Power-Pads]

Okay, now I get it.

Charger 1 = 84V / 2.75A

Charger 2 = 82.5V / 2.75A

You choose the right charger for your needs.

Do you still have a 3rd charger with 84V / 2.75A?

If not, I am sceptical if it is good to use charger 1 + 2 with different voltages in parallel. 

[Tinkererboi]

Yes I do, but want to reduce clutter to a minimum, so 2 is enough for me. It works fine, once the battery reaches 82.5v the first charger switches off.

It is true batteries should never have different voltages in parallel, as the concern is the batteries try to charge each other in an endless loop and very quickly kill each other.

However, in this case the voltage source is not a battery but a charger so there is no problem, or a fully charged battery at 84v would be able to damage a charger set for 82v.

It is for this same reason that EUC manufacturers build wheels with two charge ports. This allows users to use different chargers in each port. If it were unsafe manufacturers would have stopped producing dual charging ports long ago or at least come up with some countermeasure that makes it impossible to use two different chargers at once.

[EUC Custom Power-Pads]

All right, that was your plan. Almost charge only up to 82.5V, then it goes on with half power. 

I know it's possible to charge with different chargers and different currents at the dual port. The statements of the manufacturer were as far as I can remember but always so that it is recommended to use two identical chargers with the same amperage to avoid problems. 

I don't have a plan myself, just wanted you to know what statements have already been made here.