10 Questions You Should to Know about 60v lithium battery

Battery research is focusing on lithium chemistries so much that one could imagine that the battery future lies solely in lithium. There are good reasons to be optimistic as lithium-ion is, in many ways, superior to other chemistries. Applications are growing and are encroaching into markets that previously were solidly held by lead acid, such as standby and load leveling. Many satellites are also powered by Li-ion.

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Lithium-ion has not yet fully matured and is still improving. Notable advancements have been made in longevity and safety while the capacity is increasing incrementally. Today, Li-ion meets the expectations of most consumer devices but applications for the EV need further development before this power source will become the accepted norm. BU-104c: The Octagon Battery – What makes a Battery a Battery, describes the stringent requirements a battery must meet.

As battery care-giver, you have choices in how to prolong battery life. Each battery system has unique needs in terms of charging speed, depth of discharge, loading and exposure to adverse temperature. Check what causes capacity loss, how does rising internal resistance affect performance, what does elevated self-discharge do and how low can a battery be discharged? You may also be interested in the fundamentals of battery testing.

• BU-415: How to Charge and When to Charge?
• BU-706: Summary of Do’s and Don’ts

What Causes Lithium-ion to Age?

The lithium-ion battery works on ion movement between the positive and negative electrodes. In theory such a mechanism should work forever, but cycling, elevated temperature and aging decrease the performance over time. Manufacturers take a conservative approach and specify the life of Li-ion in most consumer products as being between 300 and 500 discharge/charge cycles.

In , small wearable batteries deliver about 300 cycles whereas modern smartphones have a cycle life requirement is 800 cycles and more. The largest advancements are made in EV batteries with talk about the one-million-mile battery representing 5,000 cycles.

Evaluating battery life on counting cycles is not conclusive because a discharge may vary in depth and there are no clearly defined standards of what constitutes a cycle(See BU-501: Basics About Discharging). In lieu of cycle count, some device manufacturers suggest battery replacement on a date stamp, but this method does not take usage into account. A battery may fail within the allotted time due to heavy use or unfavorable temperature conditions; however, most packs last considerably longer than what the stamp indicates.

The performance of a battery is measured in capacity, a leading health indicator. Internal resistance and self-discharge also play roles, but these are less significant in predicting the end of battery life with modern Li-ion.

Figure 1 illustrates the capacity drop of 11 Li-polymer batteries that have been cycled at a Cadex laboratory. The 1,500mAh pouch cells for mobile phones were first charged at a current of 1,500mA (1C) to 4.20V/cell and then allowed to saturate to 0.05C (75mA) as part of the full charge saturation. The batteries were then discharged at 1,500mA to 3.0V/cell, and the cycle was repeated. The expected capacity loss of Li-ion batteries was uniform over the delivered 250 cycles and the batteries performed as expected.

Eleven new Li-ion were tested on a Cadex C battery analyzer. All packs started at a capacity of 88–94% and decreased to 73–84% after 250 full discharge cycles. The mAh pouch packs are used in mobile phones.

Although a battery should deliver 100 percent capacity during the first year of service, it is common to see lower than specified capacities, and shelf life may contribute to this loss. In addition, manufacturers tend to overrate their batteries, knowing that very few users will do spot-checks and complain if low. Not having to match single cells in mobile phones and tablets, as is required in multi-cell packs, opens the floodgates for a much broader performance acceptance. Cells with lower capacities may slip through cracks without the consumer knowing.

Similar to a mechanical device that wears out faster with heavy use, the depth of discharge (DoD) determines the cycle count of the battery. The smaller the discharge (low DoD), the longer the battery will last. If at all possible, avoid full discharges and charge the battery more often between uses. Partial discharge on Li-ion is fine. There is no memory and the battery does not need periodic full discharge cycles to prolong life. The exception may be a periodic calibration of the fuel gauge on a smart battery or intelligent device(See BU-603: How to Calibrate a “Smart” Battery)

The following tables indicate stress related capacity losses on cobalt-based lithium-ion. The voltages of lithium iron phosphate and lithium titanate are lower and do not apply to the voltage references given.

Note: Tables 2, 3 and 4 indicate general aging trends of common cobalt-based Li-ion batteries on depth-of-discharge, temperature and charge levels, Table 6 further looks at capacity loss when operating within given and discharge bandwidths. The tables do not address ultra-fast charging and high load discharges that will shorten battery life. No all batteries behave the same.

Table 2 estimates the number of discharge/charge cycles Li-ion can deliver at various DoD levels before the battery capacity drops to 70 percent. DoD constitutes a full charge followed by a discharge to the indicated state-of-charge (SoC) level in the table.

Depth of Discharge Discharge cycles NMC LiPO4 100% DoD ~300 ~600 80% DoD ~400 ~900 60% DoD ~600 ~1,500 40% DoD ~1,000 ~3,000 20% DoD ~2,000 ~9,000 10% DoD ~6,000 ~15,000

* 100% DoD is a full cycle; 10% is very brief. Cycling in mid-state-of-charge would have best longevity.

Lithium-ion suffers from stress when exposed to heat, so does keeping a cell at a high charge voltage. A battery dwelling above 30°C (86°F) is considered elevated temperature and for most Li-ion a voltage above 4.10V/cell is deemed as high voltage. Exposing the battery to high temperature and dwelling in a full state-of-charge for an extended time can be more stressful than cycling. Table 3 demonstrates capacity loss as a function of temperature and SoC.

Temperature 40% Charge 100% Charge 0°C 98% (after 1 year) 94% (after 1 year) 25°C 96% (after 1 year) 80% (after 1 year) 40°C 85% (after 1 year) 65% (after 1 year) 60°C 75% (after 1 year) 60% (after 3 months)

Most Li-ions charge to 4.20V/cell, and every reduction in peak charge voltage of 0.10V/cell is said to double the cycle life. For example, a lithium-ion cell charged to 4.20V/cell typically delivers 300–500 cycles. If charged to only 4.10V/cell, the life can be prolonged to 600–1,000 cycles; 4.0V/cell should deliver 1,200–2,000 and 3.90V/cell should provide 2,400–4,000 cycles.

On the negative side, a lower peak charge voltage reduces the capacity the battery stores. As a simple guideline, every 70mV reduction in charge voltage lowers the overall capacity by 10 percent. Applying the peak charge voltage on a subsequent charge will restore the full capacity.

In terms of longevity, the optimal charge voltage is 3.92V/cell. Battery experts believe that this threshold eliminates all voltage-related stresses; going lower may not gain further benefits but induce other symptoms(See BU-808b: What causes Li-ion to die?) Table 4 summarizes the capacity as a function of charge levels. (All values are estimated; Energy Cells with higher voltage thresholds may deviate.)

Charge Level* (V/cell) Discharge Cycles Available Stored Energy ** [4.30] [150–250] [110–115%] 4.25 200–350 105–110% 4.20 300–500 100% 4.13 400–700 90% 4.06 600–1,000 81% 4.00 850–1,500 73% 3.92 1,200–2,000 65% 3.85 2,400–4,000 60%

Every 0.10V drop below 4.20V/cell doubles the cycle but holds less capacity. Raising the voltage above 4.20V/cell would shorten the life. The readings reflect regular Li-ion charging to 4.20V/cell.

With competitive price and timely delivery, Senix sincerely hope to be your supplier and partner.

Guideline: Every 70mV drop in charge voltage lowers the usable capacity by about 10%.
Note: Partial charging negates the benefit of Li-ion in terms of high specific energy.

* Similar life cycles apply for batteries with different voltage levels on full charge.
** Based on a new battery with 100% capacity when charged to the full voltage.

Experiment: Chalmers University of Technology, Sweden, reports that using a reduced charge level of 50% SOC increases the lifetime expectancy of the vehicle Li-ion battery by 44–130%.

Most chargers for mobile phones, laptops, tablets and digital cameras charge Li-ion to 4.20V/cell. This allows maximum capacity, because the consumer wants nothing less than optimal runtime. Industry, on the other hand, is more concerned about longevity and may choose lower voltage thresholds. Satellites and electric vehicles are such examples.

For safety reasons, many lithium-ions cannot exceed 4.20V/cell. (Some NMC are the exception.) While a higher voltage boosts capacity, exceeding the voltage shortens service life and compromises safety. Figure 5 demonstrates cycle count as a function of charge voltage. At 4.35V, the cycle count of a regular Li-ion is cut in half.

Besides selecting the best-suited voltage thresholds for a given application, a regular Li-ion should not remain at the high-voltage ceiling of 4.20V/cell for an extended time. The Li-ion charger turns off the charge current and the battery voltage reverts to a more natural level. This is like relaxing the muscles after a strenuous exercise(See BU-409: Charging Lithium-ion)

Figure 6 illustrates dynamic stress tests (DST) reflecting capacity loss when cycling Li-ion at various charge and discharge bandwidths. The largest capacity loss occurs when discharging a fully charged Li-ion to 25 percent SoC (black); the loss would be higher if fully discharged. Cycling between 85 and 25 percent (green) provides a longer service life than charging to 100 percent and discharging to 50 percent (dark blue). The smallest capacity loss is attained by charging Li-ion to 75 percent and discharging to 65 percent. This, however, does not fully utilize the battery. High voltages and exposure to elevated temperature is said to degrade the battery quicker than cycling under normal condition. (Nissan Leaf case)

• Case 1: 75–65% SoC offers longest cycle life but delivers only 90,000 energy units (EU). Utilizes 10% of battery.
• Case 2: 75–25% SoC has 3,000 cycles (to 90% capacity) and delivers 150,000 EU. Utilizes 50% of battery. (EV battery, new.)
• Case 3: 85–25% SoC has 2,000 cycles. Delivers 120,000 EU. Uses 60% of battery.
• Case 4: 100–25% SoC; long runtime with 75% use of battery. Has short life. (Mobile , drone, etc.)

* Discrepancies exist between Table 2 and Figure 6 on cycle count. No clear explanations are available other than assuming differences in battery quality and test methods. Variances between low-cost consumer and durable industrial grades may also play a role. Capacity retention will decline more rapidly at elevated temperatures than at 20ºC.

Only a full cycle provides the specified energy of a battery. With a modern Energy Cell, this is about 250Wh/kg, but the cycle life will be compromised. All being linear, the life-prolonging mid-range of 85-25 percent reduces the energy to 60 percent and this equates to moderating the specific energy density from 250Wh/kg to 150Wh/kg. Mobile phones are consumer goods that utilize the full energy of a battery. Industrial devices, such as the EV, typically limit the charge to 85% and discharge to 25%, or 60 percent energy usability, to prolong battery life(See Why Mobile Batteries do not last as long as an EV Battery)

Increasing the cycle depth also raises the internal resistance of the Li-ion cell. Figure 7 illustrates a sharp rise at a cycle depth of 61 percent measured with the DC resistance method(See also BU-802a: How does Rising Internal Resistance affect Performance?) The resistance increase is permanent.

Note: DC method delivers different internal resistance readings than with the AC method (green frame). For best results, use the DC method to calculate loading.

Figure 8 extrapolates the data from Figure 6 to expand the predicted cycle life of Li-ion by using an extrapolation program that assumes linear decay of battery capacity with progressive cycling. If this were true, then a Li-ion battery cycled within 75%–25% SoC (blue) would fade to 74% capacity after 14,000 cycles. If this battery were charged to 85% with same depth-of-discharge (green), the capacity would drop to 64% at 14,000 cycles, and with a 100% charge with same DoD (black), the capacity would drop to 48%. For unknown reasons, real-life expectancy tends to be lower than in simulated modeling(See BU-208: Cycling Performance)

Li-ion batteries are charged to three different SoC levels and the cycle life modelled. Limiting the charge range prolongs battery life but decreases energy delivered. This reflects in increased weight and higher initial cost.

Battery manufacturers often specify the cycle life of a battery with an 80 DoD. This is practical because batteries should retain some reserve before charge under normal use(See BU-501: Basics about Discharging, “What Constitutes a Discharge Cycle”) The cycle count on DST (dynamic stress test) differs with battery type, charge time, loading protocol and operating temperature. Lab tests often get numbers that are not attainable in the field.

What Can the User Do?

Environmental conditions, not cycling alone, govern the longevity of lithium-ion batteries. The worst situation is keeping a fully charged battery at elevated temperatures. Battery packs do not die suddenly, but the runtime gradually shortens as the capacity fades.

Lower charge voltages prolong battery life and electric vehicles and satellites take advantage of this. Similar provisions could also be made for consumer devices, but these are seldom offered; planned obsolescence takes care of this.

A laptop battery could be prolonged by lowering the charge voltage when connected to the AC grid. To make this feature user-friendly, a device should feature a “Long Life” mode that keeps the battery at 4.05V/cell and offers a SoC of about 80 percent. One hour before traveling, the user requests the “Full Capacity” mode to bring the charge to 4.20V/cell.

The question is asked, “Should I disconnect my laptop from the power grid when not in use?” Under normal circumstances this should not be necessary because charging stops when the Li-ion battery is full. A topping charge is only applied when the battery voltage drops to a certain level. Most users do not remove the AC power, and this practice is safe.

Modern laptops run cooler than older models and reported fires are fewer. Always keep the airflow unobstructed when running electric devices with air-cooling on a bed or pillow. A cool laptop extends battery life and safeguards the internal components. Energy Cells, which most consumer products have, should be charged at 1C or less. Avoid so-called ultra-fast chargers that claim to fully charge Li-ion in less than one hour.

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References

Thanks for this reply. The manufacturer tells me the lithium battery is 17 in series.

Odd, since the one you link that yours is supposed to be based on is 19s LiFePO4.

If yours is only 17s LFP, then it would be much lower voltage, not even 60v nominal, but only about 54v nominal, and only 62v at full charge.

It would not be 73v full, and if it is charging to that then it is being severely overcharged to 4.3v per cell, which will degrade the cells, rapidly aging the pack, and potentially damaging them in a way that could lead to a fire.

But the below gives very different specifications than the linked pack (you use the same link as you originally did, which is for an LFP or LiFePO4 pack, which is *not* what the "mfctr" quote says the pack is built from). So the battery builder did not build you anything like what you linked, so if you intended to buy what was linked but in a larger capacity, they did not do what you asked them to, and sold you a totally different battery.

Yes 17s. Sorry, It’s might actually lithium not LiFePo. Does that make a difference? Custom Moped Scooter/ Motorcycle Battery 60V 100Ah Lithium Battery Pack - SmartPropel Lithium Battery

This is from the mfctr:
it is normal that the battery voltage is higher than 70V. The 60V battery is by 17 series nominal 3.6V battery assemble, so that voltage is 17*3.6=61.2V , the cell voltage range is 3.0V-4.2V(when full charged), so that full charge voltage is 4.2*17=71.4V，so that voltage higher than 70V is normal, and if the lcd show 73v is not a problem and you can continue to use dear

Even 71.4v could actually be a problem for a 17s pack that is made of nominally 3.6v cells, since 3.6v Li-Ion typically charges to 4.1v not 4.2v, sometimes 4.15v. Charging such cells to 4.2v is overcharging and will age them faster, degrading them and damaging them.

But 73v on them is definitely overcharging them, as that puts them at just about 4.3v per cell, which is too high even for 4.2v full cells.

If it has a working balancing BMS, it should also not remain at 73v, as the BMS should drain all the cells down to their max charge level (whatever it is programmed for; presumably 4.2v in this case since the pack builder says they are 4.2v full type cells (which I suspect is not correct, and are actually 4.1v full types)).

I recommend borrowing a second multimeter and making sure it's battery is new and good (a bad battery can cause a wrong reading), then using it to verify the voltages you see on the new battery pack and everywhere else you are measuring voltages.

If it still shows 73v on the battery, and you are using the charger it came with, they sent you the wrong charger or the wrong battery or both, *and* the BMS is probably not working or not correctly programmed or does not have a balancing function so it cannot fix an overcharged cell.

Are there typically fuses in the controllers? I looked at the wiring and did not see a fuse anywhere else.

It won't be in the controller if your lights and such don't work. It has to be somewhere between the battery and the rest of the system including the DC-DC for the lights.

You may wish to draw yourself up a complete wiring diagram of every wire and every connection and device on the trike for your reference.

It may also help those helping you identify problems either at present or in future. Since the motor is only w, you might want to be careful about using an even bigger controller--the one you have is already rated to allow more power to the motor than it was designed for, so an even bigger one creates even more possibility for overheating.

FWIW, the lead batteries could probably provide more than 80A. They would probably sag in voltage under load doing that, but unlike the lithium battery wouldn't just turn off when that is exceeded. (that is what the 80A BMS does--turns off if 80A is exceeded, or if voltage is too high, or too low).


Regarding controller current vs battery current.

The battery being *able* to supply more current doesn't mean anything if the controller current limit is only 42A--it means it will only draw 42A and then limit at that.

So having an 80A BMS just means the battery can easily handle the 42A current the controller will draw at maximum load.

Getting a bigger controller only increases the stress on the battery and motor (assuming that the load you place on the motor via your riding style and riding conditions could draw more total power than what the controller can supply at present), and doesn't change the stress the controller is under.


*However*...your controller has a *90A* current limit, but your BMS is only designed for 80A. This means that whenever you draw that 90A, your BMS should shut down, turning power to the entire system off, until the BMS is reset. (that reset may be a timer internally, or a load monitor, so it resets on it's own once load is removed, or it may be manual either by reset button or by connecting the charger to it. Some BMS actually require connecting them to software on a computer or BT to an app on a to force a reset, which makes them very hard to use in a real world application).


What this means is that your battery is not actually good enough for your controller, if your riding conditions and style ever use the full capabilities of the controller, because it will then draw 90A, and the BMS will have to turn off to protect the battery against overcurrent.

If the BMS isn't correctly designed (not uncommon) it can actually even damage the BMS from a sequence of events where the switches it uses (FETs) overheat and fail, sometimes leaving the BMS stuck on so it can no longer prevent overcharge, overdischarge, or over current, etc. Sometimes it leaves it nonfunctional, so there is no output from the battery.




The order in which to pick parts is that you pick the motor to match the load your system will see, so that it can easily do the job you need the vehicle to do for you.

Then you pick a controller to support that load and run that motor appropriately for your usage.

Then you pick a battery that can supply the voltage and current that those two things need to do the job they have to do for you, and has enough capacity to do that job for the length of time / distance you need to do the job for.


So...you don't need to upgrade the controller to match the battery.

You say I don’t need to change the controller to match the battery - but it seems like I may have to as they are mismatched (90A controller vs 80A Battery BMS). Or?
.

Since I have this very expensive battery and a w motor any advising on how to pick a controller that would work best / better would be appreciated.

Well, it depends on whether or not your controller needs more power than the battery can provide in order to do the job it does for you.

Below are a lot of thoughts that I am too tired to properly consolidate, and I apologize for making it sound more complicated than it is....

Knowing why the system stopped working would help, but unfortunately it's one of those situations where we just can't know unless it fails again and you can trace down why. (if you can draw yourself a complete wiring diagram it will help you trace down any problems you have now or in future).

If it was the battery shutting down it's output because it was overloaded, then you either need a better battery (higher current capability), or a "smaller" controller (lower current demand).

If you change the controller to match the battery's limitation, but the job the trike has to do for you needs more power than a smaller controller could provide, then it won't do the job as well as it would if it just had a battery able to handle the job.

If the controller is programmable, you might be able to just lower it's current limit to what the battery is meant to support. But you'd have to get any software to do that from the controller manufacturer, or from the trike manufacturer, as it will be specific to the controller brand and model, and probably also require a cable to a computer to access. (sometimes these things are accessible via a display that's wired to the controller as part of the system, but may need a password to access, and usualy need a manual to explain the settings as they typically don't have descriptions in the menus, just cryptic abbreviations or parameter numbers and values).


But before any of that: Did the system work fine for your usage and needs, other than range, before the battery swap? How long has been in use in the original configuration?

If so, you don't really need to change anything at all, other than perhaps toning down the current from the controller.

*Or*

if the BMS does shut down the system because of overload (you'll see this during acceleration, on hills, against headwinds, whenever the load on the motor is highest), you may be able to just change out the BMS (or reprogram it if it has that ability),

*if*

the cells can handle the higher load safely. To know that for sure, you have to find out which specific cells they used, and find a datasheet on them from the cell manufacturer.

It is likely that they could handle at least short periods of the higher current, and can probably handle it long term, because most EV-sized cells can continuously handle at least 1C, or 1 x the capacity of the pack, as Amps. Meaning, a 150Ah pack can usually handle at least 150A. Most can handle at least 2C, or 300A in this case. Even if it only does 300A momentarily, and 150A continuously, it is much more than you need.

It is probably only the BMS that is the limiting factor; it's probably just not physically capable of more because of the FETs in it, so it would have a current limit to protect them.

If the battery voltage doesn't sag much even when under the highest load (up to the point the BMS shuts off), the cells can handle the current.

If the voltage sags a lot the higher the load is, they may not be able to handle it, but it depends on how far they sag.

For context, I did run this battery choice by the vehicle and battery manufacturers in China and they both gave the thumbs up FWIW. Lol.

Unfortunately it's not uncommon for the people that "make" these things to not actually know anything about what they are building / selling, because they may not actually be the ones that designed them, and may not know how this stuff works--they may just build it and sell it.

If they did understand how these work, they would not have approved a battery only capable of 80A for a controller that could need to draw 90A.

(They also probably shouldn't use a "w" motor for a "w" controller that has voltage and current ratings that actually indicate w capability...but it depends on the design intent for the system...if it was only intended for flat roads with no wind and slow speeds it would be ok, but if it has frequent accelerations from a stop or has to climb hills it could take so much power it could overheat the motor if it's really only able to handle that rated power. (this sort of thing with ratings vs actual ability is not a clear-cut exact thing, because not everyone uses the same method for determining the ratings, and some are not even "real" ratings, but just marketing numbers that sound good to them...and you can't know which are, arent', etc).

(They also would not have provided a charger that is that far over the max charging voltage the pack should ever see. But that's something else you still need to recheck, becuase if it does actually reach 73v, you don't want to keep using a charger that is too high a voltage for the pack; there are various failure modes of BMS along with cell aging that could chain in ways that allow significant overcharging of one or more cells.

And they should be concerned that the charger voltage reads that high, and not just blow off the possibility it could be a real reading with the possible consequences)

I’m not looking to go fast, I was just trying to get more range with the upgraded battery.

Well, you probably will, given that while Lithium (used within it's limits) provides it's full capacity for a good long while,
lead doesn't ever even give but maybe half of its' nameplate capacity in this type of usage, and the Ah you had in lead is probably less than what this pack advertises itself as.

Do you think my current controller is fine?

And yeah, the motor is probably way underpowered. Maybe I can upgrade to W with this current controller? Honestly after some initial research I was lost trying to understand which motor to choose / gearing. Not many people have or work on these kind of vehicles!

If the system does what you need it to do, and doesn't give you problems, then you don't need to change anything.

If it does give you problems, then the most detailed description of those you can give, along with what you were doing and under what driving conditions, leading up to it and during the problem, will help us help you find out why

Also more context: this is a very heavy food cart trike. About lbs. .

Here it is for reference. It’s a coffee truck!

It's slightly bigger than my SB Cruiser heavy-cargo trike.

The SB Cruiser : Amberwolf's 2WD Heavy Cargo Trike & Dog Carrier

This thing replaces Delta Tipper...er, Tripper v1.0, whcih was cannibalized to build it. https://endless-sphere.com/forums/viewtopic.php?f=2&t= It's mostly Dogman's fault ;) ...er, inspiration, as he suggested it as a joint build for his trip out here this year. Tiny and Yogi discuss...






I appreciate the tree-planting (I have a big yard full of them I've been growing the last couple of decades, but this year's summer is so hot for so long they're not doing very well and are taking some severe pruning).

Where do yours get planted?

Thanks so much again for your thoughtful replies. They are really helping

That’s a cool cargo bike!

Thanks...someday I'd like to build a new version with all the things I learned from this one, but it would be expensive (a few thousand dollars) because I would like to use all-new better-quality materials in it's construction, and have some parts made for me (lasercut, watercut, cnc, etc) to save me a LOT of work and headaches)

There’s another component that might have given me the trouble - a DC/AC 12V converter that is next to the controller.

Just to make sure we're thinking of the same thing, those are more commonly called DC-DC (DC-AC are *usually* used to get wall-level power (110VAC) out of a lower voltage DC (like the boxes you plug into a cigarette lighter socket in a car, that have a wall-outlet or few on them).

BTW, if that is actually a true 12v output (verifiable with a voltmeter), you can get better lighting / etc performance by changing it to an automotive-12v unit that outputs 13.6-14.4v (which is what automotive lights/etc are actually designed to run on). It's almost certain that everything on the 12v circuit is really built to run on the slightly higher voltage, but is something to verify if you go this route.

Thanks to your guidance I’m guessing that somehow tripped as the lights, dash, etc would jot respond in addition to the controller. Currently trying to understand why it might have tripped.

Normally both of those are wired to whatever contactor, relay, etc that is controlled via the keyswitch, so normally if one doesn't get power, neihter does the other.

If the keyswitch *also* controls your roof motor, meaning that doesn't work when the key is off, then it is likely they all run off the same source and should all fail at the same time.

Since the roof motor does work when the other two don't, it isn't run off the same power source. It can't run off the 12v source, as the (12v?) lights didn't work but it did.

This is unlikely simply because the original batteries were lead, whcih don't have separate charge/discharge connections, but:

If the roof motor is meant to run right off battery voltage, it could be wired to the battery pre-contactor/keyswitch/etc., and if the battery has a charge port that's wired to the charger output separately from the discharge port that runs to your controller/dc-dc/etc, then the roof motor wired to that would still work even if the battery's BMS shut off it's output due to some limit in the battery being exceeded (because the charge port can't prevent power from coming out of the battery, only going into it).

If it *is* wired that way, that should be corrected so it goes to the discharge port instead, so the battery can't be damaged if it *has* tried to shut off all discharge.


Finding out exactly where the roof motor is wired into the rest of the trike would be very helpful in finding the source of the problem before it happens again and strands you somewhere.

I was wrong about the battery charging to 73v - I was taking that from the dash display, which I understand now is not accurate. The onboard battery display says 71.4 when fully charged - matching the charger rating.

Tha'ts good. Depending on the display, it might be calibratable. If not, and you find it necessary, you can replace it with a better power meter that actually measures Wh used, which along with voltage is a much better indicator of remaining power than just voltage alone, if that matters. Some of the meters (like the Cycle Analyst from ebikes.ca) can also provide Wh/mile which helps you know how much range you can get out of the remaining Wh.