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Slow charge

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(@freddez)
Active Member
Joined: 2 years ago

Hi,

I would like to be able to charge my CPX batteries slowly when I have a little excess production from my solar panels (between 200 and 500W).

Is it possible to force the original charger to reduce power, like when the battery is around 80% ? Or should I buy a less powerful charger ? I've seen 4A 17s chargers pointed by @curlyboi , but how to deal with the 7 pins battery plug ?

10 Replies
curlyboi
Posts: 28
(@curlyboi)
Eminent Member
Joined: 3 years ago

The connector pinout is explained on our Wiki - https://wiki.voltgaraz.cz/index.php/Battery_connector#Gen_2

Just short 2 to Negative and the battery will accept any DC charger...

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6 Replies
(@freddez)
Joined: 2 years ago

Active Member
Posts: 4

@curlyboi OK thank you !

So I will get the 300W/4A charger

Did you find a separate gen-2 male plug ? Or did you do it differently?

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(@andre)
Joined: 1 year ago

Active Member
Posts: 19

@curlyboi ... i fount no way to send a private message so i try it on this way... i use your wiki to set my batterie in mode A to get out the power but it aktived the battery not with the full power so i can´t use it as a powerpank. i looks like it allowed only 3-5 Amp get out... do u have any idea how i can solve that??? regards Andre

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curlyboi
(@curlyboi)
Joined: 3 years ago

Eminent Member
Posts: 28

@andre What happens if you try to draw more? Are you talking about 3-5A on the 230V end or on the 70.5V end? The battery will shut down when over-current is detected, but that happens around 90A on 70.5V

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(@andre)
Joined: 1 year ago

Active Member
Posts: 19

@curlyboi  i talk from the 70V site.

i use an 800 W dc dc step down converter and a victron 48v converter for transfer to 230V. So around 68V out ot the Batterie(60V45ah cpx le3), in put dc dc converter then 52-53V out to the victron converter (victron converter has 48V 500W).

it looks like the bms turns off and on in very short time.... If i use a normal bulb (230V) i can see it flicker (Not the rigth working way :-/and the converter jump from 220-240V.

if i try to get more power like for the frige the victron converter sounds really bad and only in 1 of 10 time it not turn off and the output from my victron converter jumpt from 200 to 240 V. maybe the bms not work rigth with the dc dc converter and the victron in one line... the dc dc step down converter has an max output from 20A .

i cant see on my volatage measurement device so it must be very fast only the victron converter tells me over a status message that the input got down.

with an other 60V batterie witout bms it works fine.

 ... can it be that i have to use a resistance or must i use the can bus???....
I hear somewere that the bms only provide the power how  request by the can bus system... but there must be a way to let it work... but how

thx

Andre

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curlyboi
(@curlyboi)
Joined: 3 years ago

Eminent Member
Posts: 28

@andre Oh man, I don't think using two converters in a row is a good idea. Try getting it with just one. But for experimentation, you can put 120 Ohm resistor on the canbus line, the it is terminated by the bike or the charger, so it would make sense for it to shut down.

This is uncharted territory for me, I never tried using it as a serious power source, only for quick testing and that worked. I used 60-24v dc converter and that just worked fine.

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(@andre)
Joined: 1 year ago

Active Member
Posts: 19

@curlyboi jah i know that 2 converter is not the best way but i dont fount a DC AC converter that work with 70V Iinput only up to 56-57V. But Thx i will test it with 120 ohm reistor.

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Posts: 56
 RZEE
(@rzee)
Trusted Member
Joined: 3 years ago

Higly unsafe to charge the battery with a uncontrolled charger. [charger and battery communicate during the charging process].
There is a 8A charger available from Supersoco, they are used for VS2 model. VS2 Use identical battery. 

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1 Reply
curlyboi
(@curlyboi)
Joined: 3 years ago

Eminent Member
Posts: 28

@rzee Only some of them. CUX, TC/TSX are just dumb chargers with no data pins present on the connector anyway.

For CPX, it's a CAN BUS protocol and I have it fully reversed engineered. However! The only thing that affects charging is temperature, the battery asking for 10A instead of 15A when it's cold (i think below 5°C?). Other than that, the charging proceeds exactly the same (I have graphed measurements to prove that) as most of the charging is controlled by the onboard BMS anyway. There is CC phase that charges at whatever the charger provides (originally 15A but will happily do anything, like 6.5A what I use for charging for the last 2 years), and then it slows down as it reaches the CV phase. Finally, the charger detects the power draw under, let's say, 500mA and shuts down.

It is crucial to set the correct voltage for the charger - I have ordered a 71.4V charger (which is normal for 17S chargers) but then used its internal trimmer to lower it down to 70.5V to match the original charger. Soco uses slightly lower max voltage to prefer longetivity of the cells.

Furthermore, I have a RPi4 with CAN hat attached to my non-original charger and I use my own custom api to integrate it into my home automation (OpenHAB in this case). The home automation will shut down the charging at 92% as I don't need the extra range. I also monitor temperatures (the battery has 4 sensors inside) and stop if the temperature exceeds 35C. This never happened, but I try to be careful so I have the rule there anyway.

If my home automation crashes, it will of course continue charging until the non-original charger shuts down at 70.5V, which is basically what would happen with the original one. I have two batteries but I rarely need the range of two at the same time so I swap them as needed, using one for one day and the other the next day.

So non-original charger with substitute CAN monitoring and charging control. I use this for about 26 months, 15000km on the scooter. Recently I connected both batteries to diagnostics (as a dealer, I have full access to diagnostics). Both batteries are on 100% health and both batteries exert the same range as they did when new. I charge them at 40% speed of the original charger, to only 92% and usually discharge to about 30-35% on my daily routine. A nice bonus is that the non-original charger is taller so has 90mm fan instead of 40mm fan in the original one. It is WAY quieter, and I have swapped it for a Noctua fan to further silence it.

To be clear - all of this STILL voids warranty. But as a pretty well-educated person on the topic of li-ion batteries, I just thought I would risk this and so far the risk is well worth it.

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Posts: 56
 RZEE
(@rzee)
Trusted Member
Joined: 3 years ago

Posted by: @curlyboi

@rzee Only some of them. CUX, TC/TSX are just dumb chargers with no data pins present on the connector anyway.

The slow chargers are, the superchargers are not.

Posted by: @curlyboi

(as a dealer, I have full access to diagnostics). Both batteries are on 100% health

The SOH function is not active in the battery firmware, you will see 100% always.

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