BMSBattery 12 Fet KU123 Controller Voltage

[potatorage]

Hi, I purchased a BMSBattery 36V 500W controller last year and I was wondering what the maximum voltage I could run was. I believe there are 63V caps inside, but since I opted for the 36V version, would 16S LiFePO4 48V work with the controller without modification? Thanks!

[chvidgov.bc.ca]

Yes. I regularly run the KU123 on multiple bikes with fully charged 16S 48V Ping batteries which are around 60V fully charged. No issues so far. Unless there are two versions of the controller? I think they are identical versions, perhaps a different LVC that's all.

[Dear-user]

I confirm that it's possible to go at least to 50 volts with this controller, as I do.

But I'm curios if it is possible to go further? Replace these two 63V caps and voila! Next limit I'm aware of is 80V mosfets.

[dnmun]

yes, 48V lifepo4 is actually best when used with a 36V controller. a 48V controller has a 40.5V LVC and a 16S lifepo4 pack would only be down to about 2.5V/cell at that point under load when the controller cuts out. so 36V is better than ok.

[spuzzete]

Interesting information!

I have a ku123 controller 500w 36 volt from bmsbattery too. I am using a 10s Li-ion battery (41-42v fully charged) and I had no problems so far.

I was wondering if I can use a 15s Li-Ion battery pack (61.5v if cells charged @ 4.1v / 63.0v if cells charged at 4.2v) without changing the capacitors in the controller. Is it too risky?

[dnmun]

nope, imo the 63V is the spec, and you have to read all the legalese that goes with it but they can do more by a small margin imo. i have had my 9C infineon controller pegged at 90V stock and it did not blow up the controller 63V caps but that was for a few seconds under no load power, about a minute exposed at that voltage.

i would not last long imo if i continued, but i don't think you will have problems because of voltage breakdown with your pack. limno4 is it?

[spuzzete]

i would not last long imo if i continued, but i don't think you will have problems because of voltage breakdown with your pack. limno4 is it?

Thanks for the info dnmun.

My battery pack is actually Li-Co made with 18650 laptop cells. In the future I will probably use Li-Mn.
The voltage drops 2-4 volts on my 10s pack (from a fresh charge) applying full throttle and then voltage climbs back up. The pack is 24Ah nominal.

I have a spare KU123 controller, so I guess I will give it a try.

[Dear-user]

I belive caps should not be overvoltaged. They could withstand some short overvoltage, true, but they degrade for sure. Afaik it's not a good idea to run it that way for a long time.

Besides it's quite easy to replace them for 100V or 160V caps.

[spuzzete]

So I completed a 15s Li-Mn (Makita cells) today and I tried on the bike. The pack voltage was 61v at the beginning of the ride. No problem with the controller, the bike is really fast compared to my 10s li-ion battery pack. The acceleration is much better and I hit 45kph pretty quickly. After a couple of kms the max speed was about 42-43kph.