Need advice re: setting up a Luna Cycle 36V charger for use with Stromer ST-1

[Steve Plattner]

Two thoughts. 1) Luna charger not working. 2) Wrong size resistor. I suppose your guy checked it to be sure. The color bands of Green-Brown-Orange on the resistor says 51K ohms and Red means 2%.You still have the original Stromer charger, unmodified, and that works?

The green LED on my Luna charger, also 80%-90%-100% but no voltage display, turns red when charging. What happens if you plug it on first and then connect to the battery?

Sometimes nothing happens when I connect a charger to my batteries, in which case I power up the charger before connecting.

Hi, yes the old Stromer charger works fine (glad I still have it). I'll double check on the resistor again. I will try your suggestion: plug in charger first, then connect to battery. Worth a try for sure. Thanks for writing. I really want to make it work as I believe it will prolong my very spendy batteries lives significantly.

Two thoughts. 1) Luna charger not working. 2) Wrong size resistor. I suppose your guy checked it to be sure. The color bands of Green-Brown-Orange on the resistor says 51K ohms and Red means 2%.You still have the original Stromer charger, unmodified, and that works?

The green LED on my Luna charger, also 80%-90%-100% but no voltage display, turns red when charging. What happens if you plug it on first and then connect to the battery?

Sometimes nothing happens when I connect a charger to my batteries, in which case I power up the charger before connecting.

 

[Steve Plattner]

Ive just been told that Stromer chargers and batteries use ise Can bus communication. Preventing other chargers from working.

"A Controller Area Network (CAN bus) is a vehicle bus standard designed to allow microcontrollers and devices to communicate with each other in applications without a host computer."

I hate to hear that! I wish I had followed your advice and set up my XLR plug as an extension cable with an XT60 that would marry up to the one on the Luna Cycle. Beginning to think experiment is going up in smoke. Thanks for the updates.

 

[Steve Plattner]

One other thing--I assume that if the Luna Cycle chargers are compatible due to the CAN issue, the same would be true with the Grin Satiator?

 

[tomjasz]

I really want to make it work as I believe it will prolong my very spendy batteries lives significantly.

If what I'm told is true, you may be risking a problem.

That said there's another way to go. Every owner ought to own an inexpensive multimeter as a part of their kit. Get one. Amazon is a good source. Also invest in a 110V timer. Use your battery, take a reading at the end of the ride. Right the voltage down. Now charge using the timer and come back every half hour to check the voltage. Use those number to extrapolate the time it takes to add battery voltage.

I have a dozen customers that spent a rainy day measuring a battery with a low charge. When done riding, plug their charger in, set the timer to stop the charge at the voltage they want.

It may sound complex but it's really not. Several have been getting their battery charged at 80 or 90%, for several years, this way. All you have to do is sort how long it takes for a given voltage value. Battery is at 38V and you want it at 80% 40V then charge for x number of minutes. You just need to solve the voltage over a given time. They all have developed little cheat sheets, charts with their values.
Full charge is 42V. a 36V battery has 10 cells in series. Each 4.2V at full charge.
You want the pack to read 40.5V. But 40V-41V will give you the increase in cell life you are looking for. In a perfect world you would charge to 40.5V and that is possible by using a timer and a little bit of experimentation.

IF the experts are correct, and I believe they are, you're possibly doing your system a disservice by trying to circumvent the can bus system in place. Sell the Luna charger and chalk it off as a lesson learned.

 

[harryS]

A lithium-ion battery should be charged on timer anyway in my opinion. While it appears irritating that Stromer restricts the chargers, it is in the interests of safety and quality too. I use a AC timer on my ebike chargers just to make sure the power gets turned off if I fall asleep or leave the house. I often set my kitchen timer as a backup to tell me to go look.

That link about the battery fire was scary. So far this year, I have read about three fires that occurred while charging and one that happened while parked. I'll pay Stomer prices if the battery is rugged enough to take some knocks and has relatively fail safe electronics.

 

[tomjasz]

A lithium-ion battery should be charged on timer anyway in my opinion. While it appears irritating that Stromer restricts the chargers, it is in the interests of safety and quality too. I use a AC timer on my ebike chargers just to make sure the power gets turned off if I fall asleep or leave the house. I often set my kitchen timer as a backup to tell me to go look.

That link about the battery fire was scary. So far this year, I have read about three fires that occurred while charging and one that happened while parked. I'll pay Stomer prices if the battery is rugged enough to take some knocks and has relatively fail safe electronics.

midwayusa.com is selling a large 20MM ammo can for $40 delivered. Testing has shown an ammo can latched with the water seal gasket removed contained a lipo fire. I now charge in one of those and store in a flammable cabinet with smoke and heat alarms.
see test #4 about 6 minutes in. The rest were disasters.

 

[tomjasz]

One other thing--I assume that if the Luna Cycle chargers are compatible due to the CAN issue, the same would be true with the Grin Satiator?

I asked Grin but never got an answer. I'll call and ask for my own benefit. Someone did post that using the force charge function the Satiator would work. I don't think Grin would support that. I'll find out. DISCLAIMER I recently sold several Satiators and will likely continue to sell them.

 

[tomjasz]

One other thing--I assume that if the Luna Cycle chargers are compatible due to the CAN issue, the same would be true with the Grin Satiator?

I read Amber comments and a few others again. Have the electronic fellow check and see if red is positive and black is negative? It turns out some companies REVERSE the continuity so that other chargers won't work. I know it's crazy but re read the post. That's what Amber is suggesting I use a satiator to check. But you can check with a multimeter. With red on red and black on black does the display show a minus sign "-" when continuity is revered on all my multimeters they display the voltage with - They COULD be doing that. That would block normal chargers.

 

[Steve Plattner]

If what I'm told is true, you may be risking a problem.

That said there's another way to go. Every owner ought to own an inexpensive multimeter as a part of their kit. Get one. Amazon is a good source. Also invest in a 110V timer. Use your battery, take a reading at the end of the ride. Right the voltage down. Now charge using the timer and come back every half hour to check the voltage. Use those number to extrapolate the time it takes to add battery voltage.

I have a dozen customers that spent a rainy day measuring a battery with a low charge. When done riding, plug their charger in, set the timer to stop the charge at the voltage they want.

It may sound complex but it's really not. Several have been getting their battery charged at 80 or 90%, for several years, this way. All you have to do is sort how long it takes for a given voltage value. Battery is at 38V and you want it at 80% 40V then charge for x number of minutes. You just need to solve the voltage over a given time. They all have developed little cheat sheets, charts with their values.
Full charge is 42V. a 36V battery has 10 cells in series. Each 4.2V at full charge.
You want the pack to read 40.5V. But 40V-41V will give you the increase in cell life you are looking for. In a perfect world you would charge to 40.5V and that is possible by using a timer and a little bit of experimentation.

IF the experts are correct, and I believe they are, you're possibly doing your system a disservice by trying to circumvent the can bus system in place. Sell the Luna charger and chalk it off as a lesson learned.

Good advice. Will follow your suggestions. I have a multimeter and a simple timer that allows me to set the time in one hour increments. I will see what I can figure out.

 

[tomjasz]

I found another Gem from the response from Grin, that can ID whether or not their is a Can bus system interfering. I'm sorry but I have two Luna chargers that are junk. I'm not convince it isn't a charger problem. But this is hard to sort. I've been poking experts for days. It seem none have torn into Stromer systems. Other than a single there on ESdotCOM. Here's what I was emailed.


If there's CAN bus on the system, then there may be some 'hand-shaking' between the charger and the battery.

If this is the case, then it will likely not work.

If you have the original charger, and an oscilloscope, you can measure what the signal response is upon connecting the two devices.

Resistors are often used in communication to give specific impedance for signal drivers, so it's presence there could be for that, or it could be for a simple voltage divider, or a resistance measurement. Point is we don't know, as we have not dissected a Stromer here.

 

[tomjasz]

I really want to crack this nut. I'm frustrated that I haven't been able to.

 

[ChWh]

Hi Steve, you can charge a Stromer ST1 without a Stromer charger. I assume that the BMS functions as well but I have not verified that.
I have been using a 24v solar panel and a charge controller (MPT-7210a) to charge mine. I cut the plug off of the Stromer charger and put a xt-60 on the other end to attach to my charge controller. I usually charge to 40 volts unless I need a full charge.

Have you tried:
1) Using the Luna charger set on 100%?
2) Plugging the charger into the bike but leaving it unplugged from the wall and checking the battery voltage with a volt meter? I get battery voltage across the red and black wire of the stromer charge plug even when no charger is connected. If you have voltage on your fabricated plug then I would suspect either the incorrect resistor (I don't know what the resistor does) or that the Luna Charger is not working (I can test if you want to send it to me).

Notes on my bike:
1) I found this thread because my battery percent meter on the Stromer display never changes (always 58%).
2) My Stromer battery charger died immediately when I tried to charge using a modified sine wave inverter. DO NOT plug stromer charger into a modified sine wave inverter. This goes for the Luna charger with the 3 position switch as well. My original Luna Chargers (larger black case with no switches or displays) work fine on the modified sine wave inverter but do seem to heat up a lot more than when powered by household power. Thanks, Chris