Which BMS for Roypow 56ah 48v lifePo4

[autotechsteve]

I need to replace the BMS in my Roypow 56ah 48v pack that is in my EZGO. The cells are 56ah each, 3C continuous discharge and 5C maximum pulse discharge. The current BMS is rated for 100a but that seems low to me when you calculate the 3C continuous discharge of 156a. The data sheet for a Daly 150a BMW says BMS 150a continuous with a 260a over discharge protection. I thinks its odd that the original BMS was rated at 100a,was there a reason for this that I am not understanding? Any recommendations or help is appreciated on the best route to go for a new BMS.

[Pat911]

Forget the Daly. Go for the JK BMS. The model to get is the JK-B2A24S20P

8s-24s configurable
2A active balancer
200A continuous
350A peak
Currents can be detuned to match your cells

Cheers
Pat.

[autotechsteve]

Thank you Pat911! That looks an awesome BMS! Do you have any experience with the Daly BMS. Is one preferred over the other. Looks like the Daly is easier to get from places like Amazon but the JK has to come from China or an importer.

[augiedoggy]

Originally Posted by autotechsteve

I need to replace the BMS in my Roypow 56ah 48v pack that is in my EZGO. The cells are 56ah each, 3C continuous discharge and 5C maximum pulse discharge. The current BMS is rated for 100a but that seems low to me when you calculate the 3C continuous discharge of 156a. The data sheet for a Daly 150a BMW says BMS 150a continuous with a 260a over discharge protection. I thinks its odd that the original BMS was rated at 100a,was there a reason for this that I am not understanding? Any recommendations or help is appreciated on the best route to go for a new BMS.

Is the bms is going into protection mode and shutting down the battery on you? if not, you will get no benefit from a larger bms. I assume its giving you problems but am mentioning this just incase you think your otherwise missing out on performance or something... The cart pulls the current and unless its pulling more than 100 continuous now it wont if theres 150 available either.

If it is going into protection mode Im with Pat in recommending going to a 150a or 200a jk bms and adjusting it to match the cells.

Roypow/Eve likely chose the smaller bms for cost savings when designing the pack.

[TheCartBoy]

I'm curious, what caused the original BMS to fail, and what is the failure mode?

[autotechsteve]

I am not sure what happened to the original BMS. After testing it looks like it was not recognizing the temp sensors and it would not power on. I got this pack second hand so I am not sure of the history.
The batteries in the pack have a 3C continuous discharge and a 5C max. They are 56ah cells. This should put my continuous discharge at approx. 150amps with a max of 250amps. My thoughts on the 200a BMS are to give my self some headroom for reliability. I can change the settings to accommodate the 150amp continuous.
I agree about the low amp BMS for cost savings, it does not look very impressive.
Is there anyone trustworthy in the US that carries the JK?

Thank you guys for the help on this one!

[cascader]

Originally Posted by autotechsteve

I am not sure what happened to the original BMS. After testing it looks like it was not recognizing the temp sensors and it would not power on. I got this pack second hand so I am not sure of the history.
The batteries in the pack have a 3C continuous discharge and a 5C max. They are 56ah cells. This should put my continuous discharge at approx. 150amps with a max of 250amps. My thoughts on the 200a BMS are to give my self some headroom for reliability. I can change the settings to accommodate the 150amp continuous.
I agree about the low amp BMS for cost savings, it does not look very impressive.
Is there anyone trustworthy in the US that carries the JK?

Thank you guys for the help on this one!

It may be that other components in the high current path, such as busbars and wiring / lugs, are unsuitable for a 3C continuous discharge. If unsure, I’d suggest posting pics of the interior arrangement or component specs. If you have access to an IR camera or an IR thermometer it might be useful to check the spot heating under load.

Some people have used Docan power.

[augiedoggy]

YMMV but...

There are stateside resellers on Amazon that sell the jk bms but for about a 50-70% markup in price. Ebay similar. I have ordered all 3 of mine directly from JKs store on aliexpress... the 200amp version with the 2 amp actica balance comes for about $135 shipped and I purchased the smaller display screen that gives status and SOC as well as on and off function for an additional $15 or so.. it comes with all the wiring and connectors needed. They do have a 14 day delivery guarantee..

Edit, I've purchased cells from. Docan in Texas with good results. They are a Chinese company with a US warehouse. I did not know they carried JK bms but its been a couple years since I've dealt with them

[Pat911]

Originally Posted by autotechsteve

Thank you Pat911! That looks an awesome BMS! Do you have any experience with the Daly BMS. Is one preferred over the other. Looks like the Daly is easier to get from places like Amazon but the JK has to come from China or an importer.

Yes I’ve had personal experience with Daly. I have 3 decommissioned ones here and another one still in service. I’ve stopped using them not because they don’t work, but because they are very basic, and limited in their functions. There are far better BMS’s available at a much lower cost. They do look good though.

I concur with Augiedoggy. All JK’s Iv’e purchased have been directly from the JK BMS AliExpress store. No issues whatever. In fact, every BMS I’ve ever purchased has been from AliExpress, over 10 large smart BMS’s from Daly, JBD and JK, and also over 100 dumb low current (10A-40A) 2-6 cell units. Don’t be put off from purchasing from AliExpress, once you’ve done it once you’ll wonder why it took you so long to discover this marketplace.