The nimh battery build...
- Thread starter deacon
- Start date
Just looking at some of the feed back from that seller and some of the items bought.
Examples...
Electric bicycle Rear kit 48V 1000W BIKE RETROFIT KITS.
US $227.00
Approximately £148.35.
Shipping.
US $98.00
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10 PCS A123 NEW 18650 1000-1100mah Lifepo4 battery cell.
US $39.99
Approximately £26.13
Shipping.
FREE P&P
I think this seller is worth a look.
Seller - elephant1488
eBay UK Shop - elephant1488: Motor Kit conversion, electric bicycle, Folding bike
Regards
Tom
Examples...
Electric bicycle Rear kit 48V 1000W BIKE RETROFIT KITS.
US $227.00
Approximately £148.35.
Shipping.
US $98.00
-----------------------------------------------------------------------------------------------
10 PCS A123 NEW 18650 1000-1100mah Lifepo4 battery cell.
US $39.99
Approximately £26.13
Shipping.
FREE P&P
I think this seller is worth a look.
Seller - elephant1488
eBay UK Shop - elephant1488: Motor Kit conversion, electric bicycle, Folding bike
Regards
Tom
I had some spare time today, who am I kidding I'm retired, so I built a holder for the three batteries I have ready now. I have to build six more and will have to do something with them as well. So I took a look around the shop and found an old tackle box that I was using as a storage for my painting supplies. Not bike paint or house paint artist paint. Since I haven't used it in about a hundred years, I moved it to another box and the batteries should work nicely in it. I will have to figure out where to hang it on the bike though.
It is weird that I am going to be able to fit a 36v 27ah battery into a fishing tackle box. I think I can even hook it to the rhino drive gizmo. I have been pulling a trailer along to carry 17ahs worth of batteries. How it all works remains to be seen.
It is weird that I am going to be able to fit a 36v 27ah battery into a fishing tackle box. I think I can even hook it to the rhino drive gizmo. I have been pulling a trailer along to carry 17ahs worth of batteries. How it all works remains to be seen.
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Keeping my fingers crossed that it works out, Deacon. A tackle box size 36 volt battery lighter than the equivalent sla batteries would be just what I need for my "new" rig. I better start selling some of my junk on our local Craigs so I can finance that project. 
It all boils down to will I get a max draw of 25 amps from the battery pack. I have been able to test everything else. So I'm keeping my fingers crossed as well. With SLA you can draw enough amps from any battery pack to run the motor great for a short time but it's gone quickly. The Nimh did not allow me to draw many amps when it was just 10ah at 36v. I hope by increasing it to 36v 27ah I can pull at least 25 amps at max throttle. for a longer period of time as well. But the drop in weight and size would be great if I don't get a lot of range. Of course I hope I will.
I rewired the battery I have on hand. I'm going to use it all as a subcell in the battery pack. It will be one 12v 30ah battery The two new ones I build will be 12v 27ah @. My suggestion is that if this works and you want to build one yourself use c cell not aa. The cost is similar but there are few batteries involved so less change for a cold joint.
If I have to replace the aa it will be with C for sure. If all things were the same, I would go with D cells, But I was testing for the lowest price per ah. For that the AA has a slight advantage. Not Enough though.
If I have to replace the aa it will be with C for sure. If all things were the same, I would go with D cells, But I was testing for the lowest price per ah. For that the AA has a slight advantage. Not Enough though.
I just did a quick price comparison on ebay. A 20 ah sla battery buy it now with shipping is 57 bucks. plus 14 bucks for a 7ah battery to make the12v 27ah size I'm building now, making a total of 75 bucks more or less for a 27ah 12v sla battery.
I can build the nimh for 64.50 each shipping included. It may be cheaper in the short run to build the nimh. Now wouldn't that be a kick in the butt.
The trick is that it appears you have to build a pack that is at least the size of your motor watt to get performance. In other words you can us a 12ah sla battery and get full performance for a couple of miles but with a nimh you get pig performance I think.
So if your bike pulls 25 amps like mine does, you need to build a battery with 25ah I think. The super efficient motors would need smaller batteries. Which would be the only advantage to having a hub motor in my mind.
I will be able to make a much more intelligent conclusion when the new batteries arrive.
I can build the nimh for 64.50 each shipping included. It may be cheaper in the short run to build the nimh. Now wouldn't that be a kick in the butt.
The trick is that it appears you have to build a pack that is at least the size of your motor watt to get performance. In other words you can us a 12ah sla battery and get full performance for a couple of miles but with a nimh you get pig performance I think.
So if your bike pulls 25 amps like mine does, you need to build a battery with 25ah I think. The super efficient motors would need smaller batteries. Which would be the only advantage to having a hub motor in my mind.
I will be able to make a much more intelligent conclusion when the new batteries arrive.
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by the bye, I found a small piece of roof flashing in my shop. i cut it up to use for connectors of the c cells when they arrive. It is pretty malleable and easy to cut with kitchen scissors. I think it will be a little more secure than aluminum foil but who knows. I will just have to try it to see.
Well the batteries arrived. I built the (6) 12v 9ah batteries. They will be combined to make 2 12 27ah batteries. Those two will join my 12 30ah battery I already have built. now I just have to get the darn things charged and balanced for a first try tomorrow I hope. Turns out the batteries are larger than I thought. I'm going to have to check for a container or maybe build a lightweight trailer for it. Then again I might just do a custom holder built onto the bike. Or a soft bag I have a few of those as well. It's all up in the air right now.
I need to get them charged up first. I'm going to stay up and baby them tonight rather than leave them on the charger over night. Actually I think they need 18 or more hours to charge. They arrived here dead empty. I could barely check for continuity.
I need to get them charged up first. I'm going to stay up and baby them tonight rather than leave them on the charger over night. Actually I think they need 18 or more hours to charge. They arrived here dead empty. I could barely check for continuity.
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I should have an answer about the nimh in a few days. I got the packs together after a false start so they are charging now. It is going to rain here so it will be a day or so before I can test ridge them. In the meantime I will try to make them more secure and balance them for the beginning at least.
I am going to call anything within .1v a balance. I can charge a full 3 subcell battery at once then go back and read each subcell. If one cell is under by .1v I will just put a little more charge on it. I honestly think the batteries have to run down once or twice to get a full charge on them. We will see though since I have plenty of time now to mess with it once the weather clears.
By the way the c cells are much better to work with than all those AA. I think they are a little more expensive, (per ah) but they are more convenient to build with. The best thing to connect the cells with is duct over alum foil. Fold the foil a few times fit it to the batteries the duct tape over it. It will be flexible strong and low resistance. Or so I found, there may be better ways but this seems to work. Roof flashing does not for some reason.
If I have been right about the ah requirements for a decent ride from modern controlled release batteries, the downside is you have to buy bigger batteries. The up side is per AH if you go really big the price is almost the same if not cheaper for Nimh.
I think, and some of you guys have the new lith batteries so correct me if I'm wrong here, That the energy in any of these batteries is the same. Ie a gallon of gas is a gallon of gas no matter what color the tank.
However the differences are subtle but real in the way the batteries act. For instance from one of the members I learned that a 24v lith batter is closer to 30v when charges. That is two volts more power right up front. Now I know that the more volts the better the bike runs so that probably accounts for the guy who report more power or top end from the lithium.
The more even performance and longer range I think comes from the way the battery releases it's charge. An old chemistry battery would dump all its power out until it was exhausted. Hit a hill and it thew all it could at the motor until the demand decreased. I know for a fact that without a contoller the sla would throw over 40 amps at a 25 amp motor. I doubt that it increased the performance any.
Now I think a lithium or Nimh batter will discharge no more than it's total pack size. In other words a 20 ah battery will not discharge more than 20amps. If you have a 15 or 20 amp motor or less you wouldn't know the difference I expect. There is a lot of wasted amps from an sla on those hill climbs and accelerations.
So this is what I am expecting. If I am running a 27 amh Nimh battery pack. I expect it to give me up to 25 amps of power if I need it for hill climbing. Then I expect it to cut back as the controller calls for power decrease. The If my bike will do twelve miles an hour, I expect to be able to go about 12 miles on a charge. If I get more power than I need or if I get more range for me it's a bonus.
So tomorrow I will begin to see if I wasted my money or not. I do know it is lighter and smaller than sla batteries but is a little bigger than I thought it would be. Im going to looking for some way to carry them In a few minutes. That is fater my coffee break.
However the differences are subtle but real in the way the batteries act. For instance from one of the members I learned that a 24v lith batter is closer to 30v when charges. That is two volts more power right up front. Now I know that the more volts the better the bike runs so that probably accounts for the guy who report more power or top end from the lithium.
The more even performance and longer range I think comes from the way the battery releases it's charge. An old chemistry battery would dump all its power out until it was exhausted. Hit a hill and it thew all it could at the motor until the demand decreased. I know for a fact that without a contoller the sla would throw over 40 amps at a 25 amp motor. I doubt that it increased the performance any.
Now I think a lithium or Nimh batter will discharge no more than it's total pack size. In other words a 20 ah battery will not discharge more than 20amps. If you have a 15 or 20 amp motor or less you wouldn't know the difference I expect. There is a lot of wasted amps from an sla on those hill climbs and accelerations.
So this is what I am expecting. If I am running a 27 amh Nimh battery pack. I expect it to give me up to 25 amps of power if I need it for hill climbing. Then I expect it to cut back as the controller calls for power decrease. The If my bike will do twelve miles an hour, I expect to be able to go about 12 miles on a charge. If I get more power than I need or if I get more range for me it's a bonus.
So tomorrow I will begin to see if I wasted my money or not. I do know it is lighter and smaller than sla batteries but is a little bigger than I thought it would be. Im going to looking for some way to carry them In a few minutes. That is fater my coffee break.
I'm watching you, Deacon. I'm holding off hunting for cheap electric "toys" with sla batteries.
Btw, I found a discount battery website that sells the C cell batteries with tabs so you don't have to mess with the wife's aluminum foil. I think it was 8 batteries w/tabs for $33.35. The neat thing about what you're doing is that, with C cell nimh batteries, one can make custom shaped battery packs to fit the bike frame as well.
I'm holding off hunting for cheap electric "toys" with sla batteries. Btw, I found a discount battery website that sells the C cell batteries with tabs so you don't have to mess with the wife's aluminum foil.
I think it was 8 batteries w/tabs for $33.35. The neat thing about what you're doing is that, with C cell nimh batteries, one can make custom shaped battery packs to fit the bike frame as well.
ah i bought 30 for 67 bucks they were 9000 mah..
I got the pack boxed a few minute ago. It fits in a 6" x 7" plastic box from the dollar store. It is deep about 6 inches. I might hook it to the handle bars for testing. That would probably be the simplest thing. I can get to the balance issue later. Darn I have to go back to the workshop, I forgot to charge my sla pack. I will probably need it a while longer. Not to mention for increased range if I can use the nimh at all.
I might buy a basket for the front of the bike to carry the batteries if they work out.
My next purchase will be thirty more of those C cells to replace the battery I made from AA cells. I have a feeling I will want to do for the ease of balancing the batteries within the pack. It all rather hard to explain I'll give you a diagram if this all works.
If it doesn't rain we should know something tomorrow.
I got the pack boxed a few minute ago. It fits in a 6" x 7" plastic box from the dollar store. It is deep about 6 inches. I might hook it to the handle bars for testing. That would probably be the simplest thing. I can get to the balance issue later. Darn I have to go back to the workshop, I forgot to charge my sla pack. I will probably need it a while longer. Not to mention for increased range if I can use the nimh at all.
I might buy a basket for the front of the bike to carry the batteries if they work out.
My next purchase will be thirty more of those C cells to replace the battery I made from AA cells. I have a feeling I will want to do for the ease of balancing the batteries within the pack. It all rather hard to explain I'll give you a diagram if this all works.
If it doesn't rain we should know something tomorrow.
They were all good even, I had a hard time believing it. See if you can help that new kid out on the thread new kid needs help you have a lot of geared ebikes
I got the batteries on the bike. I put them onto a small test bike I h ave around. I did that just in case I need to go somewhere on my REAL bike. I still have the sla trailer hooked to it. So sometime tonight I will check the amount of charge on the batteries, then tomorrow I will wire it in series and give it a whirl. That is if the weather cooperates.
I'm tempted to wire it quick and go for a ride tonight, but in all fairness I should let the batteries rest a couple of hours to check the charge. At the moment it seems to be holding up pretty good. Overnight will be a good test for them.
I'm tempted to wire it quick and go for a ride tonight, but in all fairness I should let the batteries rest a couple of hours to check the charge. At the moment it seems to be holding up pretty good. Overnight will be a good test for them.
Deacon - regarding the discharge rate you talked about above: many batteries (especially lithium) are rated for the discharge rate they can tolerate. It's called C rate. You talked about it regarding charging a while back, I think. It is a multiplication factor of the ah rating. The 20ah Elite Thunderskys I'm trying out are rated at 2C continuous/10 C impulse, so that works out to 40 amps continuous. That's plenty for my 24 V 350W motor. I tried to find out what the average C rate is for NiMH but it appears you have to check each manufacturer's specs and do some calculations. You could go to some of the RC forums and check it out if you want. I think that could be a reason your early testing of the 10 ah pack ran like a pig, as you said. Here's hoping the full set works better. The Prius uses NiMH, so there must be something to them.
BTW, I took the Thunderskys out for a 7.5 mile ride yesterday. I left with them fully charged at 30.2 volts and returned with 26.5 volts. That is 2 of the "12.8 volt" packs in series. 26.5 V is about what my SLAs are at fully charged, and they're usually all in (21.5-22) after 7-8 miles. They used to go twice as far but my careless deep discharges and overcharging have really hurt them. I'll continue to report my results as they come in, but the deck has a coating of snow as I write this, so I probably won't be riding tomorrow - jd
BTW, I took the Thunderskys out for a 7.5 mile ride yesterday. I left with them fully charged at 30.2 volts and returned with 26.5 volts. That is 2 of the "12.8 volt" packs in series. 26.5 V is about what my SLAs are at fully charged, and they're usually all in (21.5-22) after 7-8 miles. They used to go twice as far but my careless deep discharges and overcharging have really hurt them. I'll continue to report my results as they come in, but the deck has a coating of snow as I write this, so I probably won't be riding tomorrow - jd
Good to know there is information on the lith before you buy it. I couldn't stand the wait so I finished wiring the batteries. I lifted the wheel hit the throttle to about half which is the point I check my sla usually to see if there is continuity. Motor jerked and the chain popped off. It looks to me like the run like pig is not going to be a problem but I won't know for sure till tomorrow.
At 12.8 my sla batteries are pretty close to being all in. 12.4 or so and they are dragging around. Since I have a 24v controller running 36v pack I have to be careful that the bike doesn't drain the batteries flat which is really 11.75 after that it is dangerous. But at ll.75v there is enough on the pack to keep the bike motor tying to turn so it is possible to run them flat easily,
One thing for sure There is a huge weight savings with these batteries. I will probably move them to the back of the bike, since there is still about 15 pounds to give the steering a fit I think.
At 12.8 my sla batteries are pretty close to being all in. 12.4 or so and they are dragging around. Since I have a 24v controller running 36v pack I have to be careful that the bike doesn't drain the batteries flat which is really 11.75 after that it is dangerous. But at ll.75v there is enough on the pack to keep the bike motor tying to turn so it is possible to run them flat easily,
One thing for sure There is a huge weight savings with these batteries. I will probably move them to the back of the bike, since there is still about 15 pounds to give the steering a fit I think.