THANK YOU everybody for your comments so far. Sorry for the delay in responding to your diagnositc questions, I live in Japan so my awake hours are different from yours
@krloz
Decreasing the b0 wire guage would have never crossed my mind to decrease current going through it, I would have thought that would only make the problem worse by making it even hotter and melt faster. If anything I would have thought to increase the gauge of the b0 to make it run ācoolerā. Can you explain your reasoning?
@SimosMCmuffin
Can you please explain why adding an in-line b0 100ohm resistor would help? Does it cut down on current going through it and redirect it to b- wire? Does doing this affect the b0 sense function when I add the resistor? I am including the closeup view of the BMS that you requested. The b0 attachment you can see is a little browned/melted from the many wire melts that have occured on this lead. Is adding a resister effectively the same thing as down gauging the wire as per krolzās suggestion (they are both adding resistance to the lead right?) or the electrical effects different of these two options?
@longhairedboy
Here are my BMS leads volt meter readings: b0-0v, b1-3.68v, b2-7.35v, b3-11.03v, b4-14.7v, b5-18.38v, b6-22v, b7-25.7v, b8-29.4v, b9-33.1v, b10-36.7v, battery pack voltage-36.7v. Since you have done so many of these evolve packs now, have you noticed like I have that some of the evolve BMS units do not have b0 wired and some do?
@darkkevind
Sorry for the confusion, in the original photo I had not soldered all the other discharge wires in yet. No, I am not bypassing the BMS. I am attaching the final BMS layout below where you can see the b-/c-/p- discharge wires correctly attached.
SO, here are my new set of questions:
What is the purpose of b0? Not all BMS units have a b0 and I thought the cell balancing of pack #1 is already accomplished with b1.
I have redone a very careful comparison of my setup compared to the second stock evolve board I have and I realized they used a 14awg wire for b- and I used a 16awg for my setupā¦can this minor difference in awg be shunting more current through b0 as a result?
I am using a 10awg for my b+ wire, and as just mentioned my b- is 16awg, Is there a problem caused by having an awg mismatach between b+ and b-? Do you need both wires to have matching awg?
In AWG big value number means small wire thickness. And low number means thick wire.
So with decrease the awg I meant increase the wire thickness. Sorry for the confusion
Balancing of cell 1 is accomplished between b0 and b1. Balance of cell 2 is between b1 Annās b2.
The thing is some bms dont carry a connecting for the first balance wire because itās the same than battery negative, so they just measure there instead.
16awg sounds way too thin. If it was 14awg to start with, definitely dont go thinner than 12awg with your new battery. Iād probably just use 10awg like the positive wire.
16 AWG can handle 10amps or even more according to some sourcesā¦ These wires should have 4 amps MAX flowing through them. Most of the time itās less than 2 amps. Iām sure this is not a wire thickness issue.
I have talk to evolve about the b0 wire because my board came without it. They said that the negative lead that is for the management and not for the straight power is not needed my bms has 11 pins but only 10 wires coming out of it. They said the negative isnāt needed when I get a chance I will take pics of my upgraded battery and the bms
@krloz
Thanks for fixing my sloppy awg/wire thickness terminology.
LOOKS LIKE THE PROBLEM IS FIXED!
Thanks to everyones input I changed the b- wire from 16awg to 12awg and i tested with some big hills pulling the max amps (60a total, 30a per motor), the b0 wire is not melting anymore!
As stated previusly the stock b- wire is 14awg and i accidently initially rewired with 16 awg, i am surprised evolve chose the stock 14awg setupā¦it so close to the margin of safety!
Question:
Can somebody explain why the 16awg resulted in b0 melting? It seems to me if the b- wire was too thin the b- should have been the wire to melt???
@longhairedboy and @Lambjr088
Thank you for confirming that there is a mix of BMS units that use all 11 balance wire and some have use 10 with the b0 clipped. @Lambjr088 please let me know if you can get more info from evolve about this. At first I thought that maybe the older BMS units were 10 leads with b0 clipped and the newer ones used all 11 but I made a VERY INTERSTEING discovery when I compared the 4 evolve gt BMS units that I have: If you look closely there are minor differences on chips/diodes/resisistors on the BMS units depending on the manufacture date/serial number:
The oldest is serial SP-M10-020-A05 date 2016-07-29 ā> it uses all 11 leads
The next is serial SP-M10-020-A07 date 2016-10-09 ā> it used 10 leads with b0 clipped
Newest (I have 2 from this batch) is serial SP-M10-020-A09 date 2016-12-08ā> it uses all 11 leads
If you will notice it is not the newest or oldest BMS units that run 10 leads but the one from the middle date production. Like I said all three of these serials have subtle differences that I can see on the board. I am so curious if there is something we can do so that b0 wire does not have to be used on any of the BMS units (one less thing to break), and I am very curious why it is the MIDDLE production BMS that seems to be configured this way.
To small of a b- wire caused a resistance when power was taken through it that caused some of the power to travel through another path. That path being the parallel b0 wire which as we know is not good for any power usage
Simply put. They were forced to share the power input to the bms And the b0 melted faster than the b- had time to heat up and melt
Hi, my Evolve Bamboo has the same issue. Can I ask what Focboxes and 6374s, BMS and a Mini remote you went with? Iām think of doing the same. Thanks, Wayne.
Actually, they all. I thought I was supposed to power switch, too, but thereās a way out of the other side that connects the power button, so I m confused. And what would those duties be?
