Destroyed $4K of alternator & regulator with a good Fuse

me3

New Member
48V system. 56V 160A APC alternator. WS500 Regulator.
200AH Winston cells.
Running at ~160A during commissioning, when, we think, the 200A Class T Blueseas fuse opened. Took out the alternator rectifier diodes (internal) and the WS500 regulator. Also opened the 15A ATC fuse to the regulator, destroying the sealed fuse holder.

Lessons.
More headroom for main line fuses. At least 50% more than expected load.
Consider slow blow fuses
Most spade fuses / holders don't cope with 48V systems(more than once)
There is no alternator protection for 48V systems. Only 24v / 12v
 

JMc

Solar Enthusiast
If the damage was caused by the surge voltage when the fuse popped, how would subbing a larger fuse be better?
 

me3

New Member
If the damage was caused by the surge voltage when the fuse popped, how would subbing a larger fuse be better?
Fuse should not have opened. System was operating fine. Inverter, solar and battery continued to operate fine.
 

Hedges

I See Electromagnetic Fields!
Maybe a TVS device could protect alternator from disconnect. Maybe a capacitor would too.

160A is 80% of 200A, shouldn't have blown. Do you know why?
"200AH Winston cells" - that's lithium. anything to do with a BMS disconnecting?
Does system regulate current? Lithium could take too much.
 

wholybee

Solar Addict
How long was it running at 160A before the fuse blew? If it were running a for a long time and the fuse in a confined or hot space, I could see the fuse blowing a lower than rated current.

I wonder if 2 sterling alternator protectors can be connected in series? Probably not, but maybe there is a way to use 2 of them. Maybe 2 of them in series, with a resistor across each one to serve as a voltage divider so each sees 24V even when they are not conducting.
 

me3

New Member
5 minutes approx. Open air space, in view of me. It was silent when it opened.
I asked re. Sterling. Answer was a firm NO.
Seems avalanche protection is difficult at 48V from what I have heard.
Both Sterling, Wakespeed and APS said there was no easy solution due to operating ranges. ie. By the time you can clamp the spike, damage is already done.
 

Short_Shot

Solar Addict
Was the engine idling by chance, and is that alt rated for 160a @ whatever idle rpm you had?

Are you absolutely sure it was only 160a at the time of failure, or are you just relying on the rating of the regulator? It seems like you (understandably) didn't actually see any current at all, which doesn't actually rule it out.

There may be a few reasons why this could have occurred which were not the fault of the fuse, but I'm no expert by any means.

Is this the best solution for the application? A BMS disconnect for example could hose everything if it truly was just the fuse that caused the destruction.
 

me3

New Member
Was the engine idling by chance, and is that alt rated for 160a @ whatever idle rpm you had?

Are you absolutely sure it was only 160a at the time of failure, or are you just relying on the rating of the regulator? It seems like you (understandably) didn't actually see any current at all, which doesn't actually rule it out.

There may be a few reasons why this could have occurred which were not the fault of the fuse, but I'm no expert by any means.

Is this the best solution for the application? A BMS disconnect for example could hose everything if it truly was just the fuse that caused the destruction.
Hard to say the exact moment it opened, but engine was at about 2500RPM
BMV712 and CerboGX. I was watching. But I do blink / look at forums etc
BMS is a risk. Alternators and Lithium are a tough combination at 48v. I'll get it fixed and keep the experiment going.
 

Smokin

New Member
Regulator is programmable through can buss to limit currect and voltage. Make want to study this in depth.
"American Power Systems, Inc.’s regulators represent the state of the art in DC charge controllers, providing optimal battery charging and care. Unlike most multi-stage regulators, the APS-500 can use both current and voltage to regulate charging."
 

me3

New Member
Regulator is programmable through can buss to limit currect and voltage. Make want to study this in depth.
"American Power Systems, Inc.’s regulators represent the state of the art in DC charge controllers, providing optimal battery charging and care. Unlike most multi-stage regulators, the APS-500 can use both current and voltage to regulate charging."
Yes, some intensive discussions have occurred.
First pass seems that having BMS, Victron 712 and AP/WS500 on single shunt gives interference to current measurements. Second dedicated shunt installed.
 

HammaMan

Solar Enthusiast
Yes, some intensive discussions have occurred.
First pass seems that having BMS, Victron 712 and AP/WS500 on single shunt gives interference to current measurements. Second dedicated shunt installed.
What's the ramp-down time on the alternator? Consider an array of the slightly larger than D cell super capacitors in series to handle up to 60v. It's enough resistance and headroom to let it regulate down before over-volting. Easy to throw together a couple relays and resistors to charge / discharge it on the alternator side before the fuse. Do you have a wiring diagram for the system?
 

Tecnodave

Solar Addict
If your load was drawing a considerable amount of current the shunt would see battery charge current but the generator will be seeing battery charge plus load which can easily be over the limit of the generator. The regulator would be blinded by reading the wrong current value. I would think that the shunt that controls the alternator would only measure the alternator current.
 
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me3

New Member
If your load was drawing a considerable amount of current the shunt would see battery charge current but the generator will be seeing battery charge plus load which can easily be over the limit of the generator. The regulator would be blinded by reading the wrong current value. I would think that the shunt that controls the alternator would only measure the alternator current.
You can choose to wire either way (but not both)
Most of profile appears to be voltage programmed, with ability to limit max charge A.
 

me3

New Member
What's the ramp-down time on the alternator? Consider an array of the slightly larger than D cell super capacitors in series to handle up to 60v. It's enough resistance and headroom to let it regulate down before over-volting. Easy to throw together a couple relays and resistors to charge / discharge it on the alternator side before the fuse. Do you have a wiring diagram for the system?
The challenge with super/ultra caps is
a) balancing - like Lithiums
b) surge current terminals - could be a couple of hundred amps
c) batteries hold energy in the top 20% of voltage. Cap energy is 0%-100% voltage. My elec engineering is real rusty, but that means you have 80+% of capacitor unused, and need to significantly oversize (10x approx)
d) If you use resistors to limit inrush current, that defeats purpose. So needs smart control.
e) My elec engineering is real rusty - need to work out inductive energy in an alternator for (x) time of operation + field energy during collapse.
 

Hedges

I See Electromagnetic Fields!
Energy in capacitor goes as square of voltage, so 80% voltage is 64% of energy.
Auto electrical might normally operate between 12V and 15V, so 20V cap could store 0.5 x (20V^2 - 15V^2) x Cfarads worth of surge energy above 15V.

Simple resistors in parallel with supercaps will keep them balanced. That should work fine while alternator runs, but size to not be excessive drain on battery when off. During voltage transients, their matching of capacitance balances them.
 

HammaMan

Solar Enthusiast
The challenge with super/ultra caps is
a) balancing - like Lithiums
b) surge current terminals - could be a couple of hundred amps
c) batteries hold energy in the top 20% of voltage. Cap energy is 0%-100% voltage. My elec engineering is real rusty, but that means you have 80+% of capacitor unused, and need to significantly oversize (10x approx)
d) If you use resistors to limit inrush current, that defeats purpose. So needs smart control.
e) My elec engineering is real rusty - need to work out inductive energy in an alternator for (x) time of operation + field energy during collapse.
The resistors were suggested as a means to possibly charge / discharge the system based upon the wiring diagram which isn't posted and the charging portion would need to be done manually -- this could be done by a simple switch / relay that allows you to charge before connection. If your alternator is live 24/7, only a small resistor between the + and - is needed so that when power is disconnected they begin to discharge (there would be a parasitic draw equal to the resistor size). This is a common method of modern electronics to slowly safe them (typically a small resistor is used)-- not all do it however. I'd highly suggest it for super caps. They can easily handle 1,000a or more, far more than the alternator outputs providing a sufficient capacity to allow the alternator to equalize the current without over-volting. I'm mentioning several possibilities because you don't have a wiring diagram posted and the precise suggestion can't be stated. Lots of variables at play.

The capacitors would be used as an accumulator. Yes, it will probably cost 200$ to build, but sometimes that's the cost of building a working solution. Doubling current limiters when they may or may not have been the problem could make an issue appear elsewhere. Besides, fuses and breakers are sized to protect a device, not sized until they stop tripping.
 
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