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[colillon]

Hello again everyone, I have a zero ds from 2013 with the mbb burned (already checked) the bms is apparently perfect, it responds well to the tests and between pins 7 and 18 of the mbb I have the corresponding 110v....before to assemble the new mbb (I haven't managed it yet) I want to check the tensions well so as not to burn the new mbb.
My main question is if anyone really knows what this Low Power B+ fuse protects? with the broken mbb that fuse broke when plugging it in, but now being on or off i still have 110v between pins 7 and 18 of the mbb, shouldn't that power be cut off when removing the fuse?? Does anyone know where this problem could come from?

[rgutt]

I suspect it has something to do with the key on input to the MBB among possibly other things. There's a schematic for a 2016 model floating around that doesn't show the lower power B+ fuse else this would be easy. However, there is already a 4-amp fuse on the 100v line to the MBB and various 12-volt fuses coming off the DC-DC converter to the standard automotive accessories like the lights, indicators, dash, etc.

When I remove the low power B+ fuse, the dash doesn't even come on. Given that the dash receives power directly from the DC-DC converter through an ATC fuse (and I doubt Zero would have doubled down on the fusing in the same wire), I have to conclude that the low power B+ fuse breaks the key on input signal to the MBB, which the MBB would use to enable the DC-DC converter.

Next chance I get, I'll probe the voltages at the fuse key on and off relative to B-. Key off I think it was about 7-1/2 volts, which is an odd value.

[TEV]

Hello again everyone, I have a zero ds from 2013 with the mbb burned (already checked) the bms is apparently perfect, it responds well to the tests and between pins 7 and 18 of the mbb I have the corresponding 110v....before to assemble the new mbb (I haven't managed it yet) I want to check the tensions well so as not to burn the new mbb.
My main question is if anyone really knows what this Low Power B+ fuse protects? with the broken mbb that fuse broke when plugging it in, but now being on or off i still have 110v between pins 7 and 18 of the mbb, shouldn't that power be cut off when removing the fuse?? Does anyone know where this problem could come from?

Try looking here: https://zeromanual.com/wiki/Main_Page

[rgutt]

Try looking here: https://zeromanual.com/wiki/Main_Page

Did you know of a particular section that would answer his question? I don't recall seeing anything about the lower power B+ fuse other than how to replace it in the unofficial manual.

[colillon]

I suspect it has something to do with the key on input to the MBB among possibly other things. There's a schematic for a 2016 model floating around that doesn't show the lower power B+ fuse else this would be easy. However, there is already a 4-amp fuse on the 100v line to the MBB and various 12-volt fuses coming off the DC-DC converter to the standard automotive accessories like the lights, indicators, dash, etc.

When I remove the low power B+ fuse, the dash doesn't even come on. Given that the dash receives power directly from the DC-DC converter through an ATC fuse (and I doubt Zero would have doubled down on the fusing in the same wire), I have to conclude that the low power B+ fuse breaks the key on input signal to the MBB, which the MBB would use to enable the DC-DC converter.

Next chance I get, I'll probe the voltages at the fuse key on and off relative to B-. Key off I think it was about 7-1/2 volts, which is an odd value.

Thanks for participating in the post, the assumptions of how the low power fuse b+ works or what they say in the manual about how to place the fuse, I have them clear, but I have realized that nobody really knows what this fuse really protects, I have made thousands of measurements and there is only one power line for the mbb from the bms and it is pin 7 and 18, low power line b+ and b-. My idea was the same that that fuse would protect the power supply of the mbb on pin 7 and that when removing or melting that fuse it would stop feeding that pin (then the mbb takes those 110v and takes them out through the enable pin that goes to the dcdc to turn on the 12v part)....the problem I find is that when I remove the low power battery b+ fuse I still have power to the 110v mbb (pins 7 and 18)

[colillon]

Hello again everyone, I have a zero ds from 2013 with the mbb burned (already checked) the bms is apparently perfect, it responds well to the tests and between pins 7 and 18 of the mbb I have the corresponding 110v....before to assemble the new mbb (I haven't managed it yet) I want to check the tensions well so as not to burn the new mbb.
My main question is if anyone really knows what this Low Power B+ fuse protects? with the broken mbb that fuse broke when plugging it in, but now being on or off i still have 110v between pins 7 and 18 of the mbb, shouldn't that power be cut off when removing the fuse?? Does anyone know where this problem could come from?

Try looking here: https://zeromanual.com/wiki/Main_Page

Thank you for your message, but I have reviewed all the wiki and forum posts...I've been looking for information about it for weeks, I've even asked "experts" from the official zero motorcycles house and no one has been able to answer me clearly, everyone world refer me to the manual (nothing is explained on the subject) or they tell me their opinion without being completely sure.

[TEV]

I suspect it has something to do with the key on input to the MBB among possibly other things. There's a schematic for a 2016 model floating around that doesn't show the lower power B+ fuse else this would be easy. However, there is already a 4-amp fuse on the 100v line to the MBB and various 12-volt fuses coming off the DC-DC converter to the standard automotive accessories like the lights, indicators, dash, etc.

When I remove the low power B+ fuse, the dash doesn't even come on. Given that the dash receives power directly from the DC-DC converter through an ATC fuse (and I doubt Zero would have doubled down on the fusing in the same wire), I have to conclude that the low power B+ fuse breaks the key on input signal to the MBB, which the MBB would use to enable the DC-DC converter.

Next chance I get, I'll probe the voltages at the fuse key on and off relative to B-. Key off I think it was about 7-1/2 volts, which is an odd value.

Thanks for participating in the post, the assumptions of how the low power fuse b+ works or what they say in the manual about how to place the fuse, I have them clear, but I have realized that nobody really knows what this fuse really protects, I have made thousands of measurements and there is only one power line for the mbb from the bms and it is pin 7 and 18, low power line b+ and b-. My idea was the same that that fuse would protect the power supply of the mbb on pin 7 and that when removing or melting that fuse it would stop feeding that pin (then the mbb takes those 110v and takes them out through the enable pin that goes to the dcdc to turn on the 12v part)....the problem I find is that when I remove the low power battery b+ fuse I still have power to the 110v mbb (pins 7 and 18)

With the main contactor of the battery off, that low power circuit is the only power supply, otherwise you won't be able to turn the bike on again, so yes, directly from the battery trough that low power b+ fuse, the BMS is powered (to log what's happening with the battery, and be able to turn the main contactor on when requested by the MBB, or charger), and also the MBB will get power to be able to turn the bike on.
That little fuse is very important, and it can ruin your day

[TEV]

Try looking here: https://zeromanual.com/wiki/Main_Page

Did you know of a particular section that would answer his question? I don't recall seeing anything about the lower power B+ fuse other than how to replace it in the unofficial manual.

No, but in my defense, I did say "try", not "look"

[colillon]

I suspect it has something to do with the key on input to the MBB among possibly other things. There's a schematic for a 2016 model floating around that doesn't show the lower power B+ fuse else this would be easy. However, there is already a 4-amp fuse on the 100v line to the MBB and various 12-volt fuses coming off the DC-DC converter to the standard automotive accessories like the lights, indicators, dash, etc.

When I remove the low power B+ fuse, the dash doesn't even come on. Given that the dash receives power directly from the DC-DC converter through an ATC fuse (and I doubt Zero would have doubled down on the fusing in the same wire), I have to conclude that the low power B+ fuse breaks the key on input signal to the MBB, which the MBB would use to enable the DC-DC converter.

Next chance I get, I'll probe the voltages at the fuse key on and off relative to B-. Key off I think it was about 7-1/2 volts, which is an odd value.

Thanks for participating in the post, the assumptions of how the low power fuse b+ works or what they say in the manual about how to place the fuse, I have them clear, but I have realized that nobody really knows what this fuse really protects, I have made thousands of measurements and there is only one power line for the mbb from the bms and it is pin 7 and 18, low power line b+ and b-. My idea was the same that that fuse would protect the power supply of the mbb on pin 7 and that when removing or melting that fuse it would stop feeding that pin (then the mbb takes those 110v and takes them out through the enable pin that goes to the dcdc to turn on the 12v part)....the problem I find is that when I remove the low power battery b+ fuse I still have power to the 110v mbb (pins 7 and 18)

With the main contactor of the battery off, that low power circuit is the only power supply, otherwise you won't be able to turn the bike on again, so yes, directly from the battery trough that low power b+ fuse, the BMS is powered (to log what's happening with the battery, and be able to turn the main contactor on when requested by the MBB, or charger), and also the MBB will get power to be able to turn the bike on.
That little fuse is very important, and it can ruin your day

I REPEAT AGAIN SINCE I SEE THAT IT IS NOT CLEAR:
Thank you very much again for participating, but either I have not been able to express myself or I am not being understood for some reason... if that fuse we are talking about protects the power line of the mbb, why by removing it I still have power in the mbb?? In other words, without that fuse connected, I still have 110v power on my mbb between pins 7 and 18 (normally it is powered on these pins).

[atomicdog]

Seems like your stuck on the idea of the fuse needing to protect the MBB. But from your description it's on the wrong side of the circuit to protect the MBB. From that and others descriptions in this thread I think it's clear the fuse is meant to protect the DC/DC and other electronics on the bike. The MBB may have a resetable fuse, internally, to protect it.

[TEV]

shouldn't that power be cut off when removing the fuse??

Yes, there should be no power anywhere with that fuse removed.

 

[TEV]

I REPEAT AGAIN SINCE I SEE THAT IT IS NOT CLEAR:
 if that fuse we are talking about protects the power line of the mbb, why by removing it I still have power in the mbb?? In other words, without that fuse connected, I still have 110v power on my mbb between pins 7 and 18 (normally it is powered on these pins).

LOL, I got stuck on your title, and didn't see the real question that was buried there

[rgutt]

I REPEAT AGAIN SINCE I SEE THAT IT IS NOT CLEAR:
 if that fuse we are talking about protects the power line of the mbb, why by removing it I still have power in the mbb?? In other words, without that fuse connected, I still have 110v power on my mbb between pins 7 and 18 (normally it is powered on these pins).

LOL, I got stuck on your title, and didn't see the real question that was buried there

The MBB has two connections to the battery. Pin 18 is a direct connection to the battery with no fuse. It is used for the MBB to pass the battery voltage to the Sevcon controller to precharge its capacitors. Without disassembling an MBB, I cannot say for sure, but I'd bet that input doesn't power anything on the MBB.

The other battery (100 volt) input to the MBB is via the key and the lower power B+ fuse. That provides the MBB the power it needs to function before the enable command is issued to the DC-DC converter from the MBB after the key switch is closed.

I should note that is speculation based on how I have seen the respective components operate. I have never seen a schematic of the MBB.

[TEV]

The other battery (100 volt) input to the MBB is via the key and the lower power B+ fuse.

A 2013 model only have the traction (96V nominal) battery, that year model doesn't have a 12V battery.

[rgutt]

The other battery (100 volt) input to the MBB is via the key and the lower power B+ fuse.

A 2013 model only have the traction (96V nominal) battery, that year model doesn't have a 12V battery.

I never said anything about another battery. I said "other battery (100 volt) input." I was referring to the fact that there are two connections between the battery pack and the MBB. One is always on (no relay or contactor) but as far as I can tell is used only to pass battery power to the key-on input of the Sevcon. The other input to the MBB passes through the low power B+ fuse and ignition switch and provides power to the MBB for its processing needs before the DC-DC converter is activated.