Helps if I post this in the correct forum:)
I just picked up a Merida 550 at a yard sale, it was cheap at $50.00. Being a 2002 model and not taken care of by the owner the batteries were shot, even though you could see by the tires the bike only had a few miles on it. Could not get the original 12V 9Ah batteries, but I found some Power Sonic 6V 9Ah batteries that I could stuff in the case. I'm guessing this is a good brand of battery from the information on the internet about them.
Took the bike out for a ride around town and found it to be quite fun, did not seem to add a ton of extra power, but knowing battery technology today did not expect miracles. I do like to modify things though, so I was wondering what are some of the things that people are doing to their bikes.
Make sure you're not under-volting the bike, that will make it seem weak.
(if you wire them up correctly, you can get the same voltage out of a set of 6v batteries that you got out of a set of 12v batteries, but I don't even know what your target voltage is)
... another thing to consider is batteries that tolerate high discharge really well. Lithium Iron Phosphate batteries are usually a good deal for the money and they tend to maintain their voltage when used at high discharge rates.
I made some modifications to my Merida and now have a second one which I plan to do a similar modification to. The second Merida I have installed a 7-speed internal hub. I also will be using DeWalt Batteries not Lead. The modifications will be very much the same as far as the remainder of the bike goes. I did replace the handlebars with some 8" rise freestyle handlebars to give me a more upright sitting position and I also replaced the seat with a more comfortable one for my backside.
Here are the modification I made.
The controller can be found here.
Throttles are here.
I used the Brake Levers with the metal levers and built-in brake switch. There are several to choose from here.
I am not affiliated with the any off site links. If you can find similar parts please feel free to use them. These are the parts I used.
I did not include the batteries. You will need a 36 Volt Battery Pack, your choice.
This conversion could also be done using a 24 Volt controller and batteries.
cost 3 years ago.
$ 8.00 + SHIPPING
|Now it's time to connect the electronics.
Follow the diagram and connect each of the connections.
Grandpa Chas S.
While my intent was to electrify my Vision recumbent, I found a little used Merida to add to my collection. Thanks to Grandpa Chas S., the wonderful piece of work is nearly broken in after 200 miles with the "turbo switch" in use. Total miles is about 400 and the original battery pack seems to be improving in capacity. (I put the 200 miles on in Florida, left it there a month ago, will return Jan/Feb and hope to put another 600 on before returning to Michigan in March. On my last ride, Dec 8th or so, we covered 30 miles and I arrived with half a charge. Things really loosened up over a couple weeks of overheating and pedaling on basically level terrain. The only hills were causeway bridges and pedaling was progressively easier with the "breaking in".
I'm not certain about this breakin effect. While a conditioning effect is part of what happened, two weeks is a limited time given I just came off regular 30 mile recumbent pleasure trips. I noticed the heat effects of running the motor with the turbo switch and opening up the bike to see the guts was the best thing for me. I'm ready to add instrumentation, temperature monitoring following the voltage monitoring already completed. Thanks for the careful documentation of your work Grandpa?
The question I have is about lubrication of the gear system. I'd like to see what the guts of the transmission look like but think that is where the heat buildup effects were more pronounced and accelerated the breakin wear that really made pedalling more efficient. The noise from the gearing is still louder than it probably should be and I wonder about changing or adding lubricant. I haven't found anyway to add, view, or imagine the transmission other than a worm gear arrangement.
Thanks again for all of your posts everyone. This really is a great learning experience for me and helps me treat this Merida with the respect it deserves.
-- Lubrication --
I drilled a 1/4 inch hole in the top of the bottom bracket and just use gearlub from time to time. My bike has some gear noise and the lub does help it some. Warning: the bottom bracket leaks so don't park it on carpet.
Grandpa Chas S.
I changed the rear sprocket such that the Merida is geared higher. This allowed electric assist up to 20 MPH, a good idea if you use it for commuting. I have tried in vain to find replacement batteries without paying the $200 wanted by Light Electric Vehicle Technologies (877-807-5388). I finally broke down and purchased from them about 3 years ago. It seems the batteries had been sitting on the shelf for a long time as their service life was much less than the original batteries that came with the bike. They do not sell the batteries separate, but only the entire pack with new key. I imagine your lack of power is partly due to the voltage difference: you have 2-6volt batteries resulting in 12 volts where the original has 2-12volt batteries resulting in 24 volts, the voltage of the motor. It would be neat to figure out how to stuff in the new lithium-ion small cell batteries that would result in a 24 volt system. They are much lighter, quicker charging, higher capacity, and are used to power the Tesla Roadster. I think they would fit in the battery pack.
I also have a Merida 500/550. Changed the rear sprocket and get electric assist now to 20 MPH, but the low gear is of course higher than before. Have had trouble locating replacement batteries...bought one (the entire case and all) about 3 years ago for $200, but it crapped out after very little use and only 2 years. I think it had been on the shelf too long. I did just find another battery that looks like a match: interstate batteries (see their website) SLA 1085. Seems to have the same dimensions and is 12 volt 9 AH just like the original Merida batteries. You will have to open the plastic case and install them. At $43 each, they are cheaper than buying the entire pack and should be fresher. Looks like the batteries you have chosen are 6voltx2 = 12 volt, but the motor is 24 volt. Thus not a lot of extra power. Try these others, they should be better. Good luck!
I have two medidas and my wife and have used up the lead acid batteries that came with them. I see your upgrade information, but the photos do not upload. I cannot tell whether you recommend a specific type of contoller for the Merida (36 volts) and the electronic diagram is not visible.
I also use a recumbant with a hub motor running at 36 volts. I would like to upgrade the recumbant to a 48 volt and transfer the 36 volt lithium polymer to the Merida.
I have a Merida 550 that I picked up in 2003. I commute to work on it, and have been riding it 9 miles a day, five days a week for coming up on 6 years now. My area is a little hilly), so that is just about the maximum range of the bike.
Replacing the batteries has been something of a pain over the years. The first set that came in the original case lasted about 10 months. By the time I had to replace them the Merida 550 had been discontinued and the special cubical batteries that fit in the case were almost impossible to find. The shop that sold me the bike was selling sets of four 6V 10AH SLAs that would fit in the case, but the set they sold me lasted barely 5 miles per charge.
I found an electric bike shop online that was selling a backup power supply; basically two off-the-shelf 12V 10AH SLAs in a bag that straps to the cargo rack. You wire a plug into the connection points and plug the battery in to that. Unfortunately the batteries didn't work as well as the originals either, and would quit after about 7 miles.
I replaced them with a set of 12V 12AH SLAs and made a new bag big enough to carry them. These had enough juice, but they were heavy, and after about a year I noticed I was breaking a lot of spokes on the rear wheel. I made a battery rack that would fit in the position of the original battery case, and this distributed the weight a little better.
The 12AH set lasted another 10 months, as did the set I bought to replace them. Based on the way I'm using them (riding over 2000 miles a year), I'm led to believe that this is appropriate for batteries that are being fully discharged every day.
Because of the wear on the bike I started looking in to NiMH batteries. I bought a battery pack from Batteryjunction, and I absolutely do not recommend dealing with them. The battery pack I got from them, a set of 20 1.2V 10AH D-cells wrapped in a rubber coating, was only able to make the 9 mile trip for about 4 months. I contacted the company and was told that they only warrantied the batteries for a month and the manufacturer for only 3 months, so I was out of luck. I stripped the rubber coating off the battery pack and tested each cell, and found that only two of them weren't holding a charge; the rest tested okay. I bought some replacement 10AH D-cells, replaced the dead cells, and added an additional cell to bring the battery pack up to the specs for battery packs recommended by the manufacturer (21 1.2V cells for a total output voltage of 25.2V), and then the battery pack worked fine. (Also, the charger they sold me with the battery was refurbished; it worked okay, but they didn't disclose this at the time of purchase).
The advantage of the NiMH pack is that it fits inside the original battery case, and it is not that difficult to wire it in. You have to be careful to wire in the temperature sensor that the charger uses to keep the battery from overheating and exploding, but once you get that done it works okay.
A NiMH power pack is supposed to last 2-3 years. I got about a year out of it before another cell died, and when I replaced it I wired in a 22nd cell because the bike had been running a little sluggish. This puts it above the specified voltage, and I burned out a fuse every month or so, but the bike ran better. I have finally worn it out this past month, and if you ignore all the defective cells I replaced I would say the battery pack lasted nearly 2 and a half years.
Based on my experience, NiMH batteries have a different discharge curve than lead acids. Where SLAs will dishcarge at a fairly constant rate that lowers slowly, NiMH output voltage lowers rapidly the longer they are in use until the bike's low-power alarm cuts off the motor. On a slight uphill grade I get about a mile before the output voltage drops enough for this to happen, even when the batteries are fresh, and this distance lowers significantly when the batteries have been discharged. I also find that overall NiMH batteries make the bike run sluggishly. I recently switched back to SLAs, and the difference is pronounced.
I switched back to SLAs incidentally because I bought another NiMH pack (again from Batteryjunction) and this time it just didn't work. This pack was a 21 cell 12AH pack, and while it tests okay, when I plug it in to the bike it runs for a dozen yards or so and then mysteriously dies with no alarm, no nothing. After a minute or so it powers back on, and it will run for another dozen yards, but then dies again. I have double checked all the connections between the batteries and can't figure out what's wrong with it. What is clear to me is that NiMH battery packs are a risk, and for the money they aren't worth it.
I would be interested to know what people's experiences are with Lithium Ion and Lithium Polymer battery packs. I see the prices are comparable to NiMH packs, but I am hestitant to risk it without knowing what I'll be getting. Also, that 7 speed hub idea looks interesting. I have to have my rear wheel rebuilt anyway, so it might be a good time to upgrade.
Do you remember the model controller you used? I have a 36V lithium battery pack from another bike I would like to use in the Merida. I looked up the website, but they have several type which might be appropriate.
It has been a while since you posted your lithium question, but I got a 24v 15ah lithium pack from pingbatteries.com that is working great thus far (about 30 charge cycles)-- the power is steady and the endurance is better than my sla's when they were new. I had already modified the original battery pack to hold some 12ah sla's and pingbattery built me a battery to fit the space available based on the dimensions I sent them. I posted some pictures of the battery for another member. Here is the link: http://picasaweb.google.com/wetzelb/2009MeridaImages# .
Due to weather and work related demands, I commute 10 miles each way about 100 days per year-- the projected lifespan of the lithium pack is 1000+ charges over several years, but only time will tell whether reality approaches that target.
How has your experience been with the ping batteries, and what was the approximate cost? Do you have pictures of that set up as well? Thanks.