Merida stock controller wiring assistance wanted

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Last seen: 9 years 11 months ago
Joined: Wednesday, May 27, 2009 - 06:57
Points: 76
Merida stock controller wiring assistance wanted

I have a Merida 550 that I would like to modify with a couple of switches to override the stock controller. At one point, a webpage with information about a 'turbo' button and a 'kill' switch was posted on a page put up by chas_stevenson. I can still find the links, but the page was on a server ('Hometown'?) that is no longer avaialable.

The kill switch I can do by splicing into the ignition wire, but if there is a better option, I need to know which wire to cut.

The turbo button kicks in the motor at maximum output until it is released-- this would be a great way to get up to a speed from whch I can maintain with pedals only-- the automatic setings work well enough for a smooth assist ride, but they are not fast enough to do the accelerating work. I can do this now by accelerating in one gear and downshifting when I reach the speed I want, but I can't do this to get up to speed for the highest gear.

I have been riding the Merida for about 18 months and it has been a good experience. I am currently using a 24v 15ah ping pack that has performed consistently down to air temperatures of 5 degrees Fahrenheit. I added 24v lights and cargo racks, so I can ride at night and carry what I need.

Side note-- people like the bike and the concept of riding to work, but nobody wants to deal with the weather (central Illinois) and traffic. Planning might solve the traffic issue, but the weather will remain.

emotions adel
Last seen: 14 years 1 month ago
Joined: Sunday, February 28, 2010 - 16:44
Points: 2
Re: Merida stock controller wiring assistance wanted

Hi Tilt. I just purchased two nearly new Meridas though the batteries are a couple years old(original). Your postings about the bikes and the mods are impressive and assuring. I plan on upgrading to Li Fe Po once I get a little more use out of these original SLA,s.
I was wondering if I could be of any help if what you need is some review of how the bike is originally wired since I haven't done any mods to mine?
P.S. My ultimate goal is to get a group effort to design a practical, semi-enclosed trike that uses a similar assist mode as the Merida to counter the added weight of the trike and enclosure but offer a real all weather riding option. All comments, technical advise and unused parts donations are welcome. BTW what real range do you get now with your Li Fe PO,s?


Last seen: 9 years 11 months ago
Joined: Wednesday, May 27, 2009 - 06:57
Points: 76
Re: Merida stock controller wiring assistance wanted

Hi, Sorry to be slow on the response, just needed enough time to put together a decent reply:

If the batteries are old, even if they were never used, they are not likely to be of much use due to both the age and the fact that they were probably not kept at full charge. SLA batteries are damaged when allowed to sit at less than a full charge for even short amounts of time.

The battery decision is a major investment that can limit your future options. I started with a new pair of 12v 12ah sla batteries that got me about 80 charge cycles-- enough to determine that the bike was a viable option for my commute. When the sla batteries ran down, I looked at the options and went with the lifepo from ping in China-- you can save money by ordering directly from their site instead of using ebay and you will have more flexibility in ordering a battery that fits your enclosure. They were expensive, but have performed well thus far in temperatures from 5 degrees Fahrenheit up to 90. The battery I ordered provides 24v 15ah and it is plenty sufficient to get me the ten miles I need even into a headwind-- I do pedal steadily. The battery maker claims a possibility of 1000+ charge cycles over five years, but I have no idea how realistic that is. At one point I received a brand new and free 24v 12ah lithium ion battery, but it lacked the charger and power transfer rack. The more I looked into the temperature sensitivity and safety concerns, the less I wanted to experiment with it-- I finally gave it back to the shop where I got it. There are also riders using Ni-cad and Ni-mh chemistries with success; however, it does sound like there are price and performance issues based on some user posts. The only real downside to my battery is that it is not easily adjustable in terms of the output voltage, if I want to go to 36v on this bike or use it with another vehicle. If I were after 48v, I could run a pair of 24v in series and get to 48v, but the Merida motor can't handle that many volts-- I am happy at 24v, but you sound like you have plans for down the road that may involve other uses for the battery.

In terms of the wiring, most of what I have done has been additions that are powered outside of the original wiring, but if I need clarification, I will let you know. If you come across wiring and especially electrical load type questions, this site is a great resource-- I got great guidance in constructing my lighting for the bike.

In terms of range, I am not certain. On the windiest days, I can average 16mph into a 20mph wind over the 10 mile commute-- some city and some country miles, but fairly flat and paved. I did change the rear sprocket with one I got from Largoscooters that added speed-- this was a great change-- the assist now hits 19.5 mph. I have thought about riding until the battery goes dead to determine the limit , but I don't want to deep cycle it unnecessarily(a holdover concern from my sla days) and the bike is a load of bricks without the assist.

I also make use of a yahoo group called power-assist that has been very helpful-- the conversations and manners veer all over the place and you will get a multitude of opinions, but great advice is also available and the construction of enclosed trikes and other possibilities is a frequent topic of conversation-- you just have to be willing to wade through the chatter.


Persona Non-Grata
Last seen: 9 years 2 months ago
Joined: Monday, October 5, 2009 - 00:31
Points: 75
Re: Merida stock controller wiring assistance wanted

I have a Merida TEV 550 that I am also trying to add a "turbo" button and a "kill" switch to it, with the bike behaving "normally" when both are off. The kill switch to avoid wasting power when I only want to pedal, and the turbo to engage the motor when the pedal rotation exceeds what the controller thinks is top speed. This happens when the bike is geared down for going up hill and the frequent rotation of the pedals in relation to the forward speed cuts out the motor and leaves me without assistance against gravity for enough time to break my momentum. The "turbo" or override switch would solve this as I would just hold it down while going uphill. I want to avoid making either switch by splicing the power supply line, either before or after the controller as this would expose me to something near 250 watts just on the other side of a switch that will be exposed to weather. However, if I could acquire an entirely waterproof switch rated to 250 watts at 24 volts that could reliably mount to the handlebars, I would feel reasonably safe. Any thoughts on this?

With a hammer, a chisle can be made. With a hammer and chistle, files can be made. With hammer, chisle, and file anything else can be made.
Kaishan k500w retired, Merida TEV500 on indefinite sabbatical, currently using a Currie E-zip Trailz.

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