construction of battery pack instructions

[deacon]

PLEASE DO NOT TRY THIS AT HOME... I HAD A FIRE WITH THESE BATTERIES. NO DAMAGE BUT THE HOUSE STINKS OF BURNING INSULATION

FAILURE MY OLD FRIEND

How not to build the battery pack: :less than 105 dollars. (You will probably need at least two)

Choose your weapons:

For the Deacon aka 1/2 ass method you will need the following items.

copper wire from a stripped electrical cord.
electrical tape (Black)
Duct tape the cloth kind not the vinyl
.
a black one foot wire (Color optional)
a white one foot wire (Color optional)

wire cutters
scissors
a multimeter or continuity tester.
Alcohol (Optional)
A Wooden jig. (optional but highly recommended)
A half empty kitchen table (or a cold workshop also not recommended)
30 nimh ‘c’ batteries at least 9500 ma.

what is heck is a jig you ask.
In this case it is a board with a rail on each side the space between the side rails is 2“ as close as possible along the whole 6+ inches in length.

Step one
Tear the duct tape so it is about an inch wide strip about a foot long. Lay it sticky side up in the jig track. Now lay five batteries (alternating the orientation from positive to negative end up) on top of the tape. Then fold the excess tape over to hold the batteries together.

Step two
Remove the batteries and stand them on their ends. This is what I call a string.

1. To do the actual assemble: cut on old electrical cord and strip off the insulation use the copper wire strands to connect the cells.

2. Solder a small piece of wire to join the tops batteries 2 & 3. then do the same with batteries 4 & 5 . continue until all batteries are wired in series to create 36volts

3. At this point attach a multimeter’s probes to each of the pack to check continuity.

4. This is where I go back and cover the pack with duct tape for insulation and to reinforcer the wire connectors.

5. Be sure to test for voltage often and not create any shorts from this points onward.

[6. strip two pieces of wire about ten inches long solder to the two end batteries cover the connection with duct tape as well.

that is pretty much all there is to it.


A tip about attaching this to your controller. For the building wire of the pack buy yourself a cheap extension cord at the walmart. About a buck and a half. Cut off the male end and attach it to the battery connection of your controller. It is important to use the male end since you don’t want a cord with power laying around to get shorted.

Use the female end of the cord to attach to the battery pack. (Important note) I used the big end of both the male and female ends as ground aka negative side of both the controller and battery. I also use the small side for the positive end. That is if you have to do a raw wire connection to the controller. Another benefit of these type ends, is that you can make multiple connections to the battery pack.

I have a male end and a wall switch on each of my chargers so I can turn them off even though they have a hot end when turned on. It allows me to plug them into the battery pack when it is one the Controller or unplug it and put two chargers on it for a faster charge and even a multimeter to read the live and resting volts.


Now I expect you know all I know about making a pack. Oh yeah now is the time to use the alcohol.

 

[wheelbender6]

Thank you for the go-by Deacon. I have read battery pack how-to's on other sites but they were beyond the comprehension of an old Marine like me. I may try to build a 24v LiPo pack like that.

 

[deacon]

lipo needs a bms im told that is why I went with the nimh. I hooked it up for a second on my hub and could see that it ran like a champ but needed more ah so I have ordered another pack. Might still need one more but I hope not.

 

[wheelbender6]

That's true, but you can get balancing chargers that contain a BMS. That is how they charge the BMS-less RC LiPo battery packs like the Turnigys.
I agree that it is better to build the BMS into the battery pack so that you don't have to remember when to balance charge the pack.
I'm still looking at the advantages of each.

 

[deacon]

One thing is for sure when the guys on this forum put their minds to it we will build the better mouse trap;

 

[paul]

deacon if you have a hobby shop near you stop in and talk to them, cars trucks and even all the new remote control airplanes are ran with batteries, the people at these shops are ussually a wealth of knowledge especially on getting the most out of batteries

 

[deacon]

good idea. Of course whenever I walk into a bike shop I walk out shaking my head. A two dollar brake cable is five dollars. Don't even ask how much a cheap wheel costs there. I do need someone who is an expert on the voltage of a battery at rest.

 

[paul]

batteries are the most important part of the rc community. bike shops think motorized bicycles are cheating and look down on us or have zero knowledge. we have no rc shops here so it did not hit me till I started thinking about what you needed to know and remembered my old rc days when I raced. batteries proper charged, balance and efficiency were your biggest goal.

 

[deacon]

I'll see if there are any hobby shops for RC here but I never heard of anything. Than again I never looked and know nothing about them. I'll take a look.

I like being in that outlaw niche were motorcyclist think we are a bother, and bicyclist think we are cheating. It's kind of cool to be out classed by the moped army even. It's a little like being a homeless person.

 

[wheelbender6]

I check things out at the "brick and mortar" stores and then buy second hand or on line to save money. Almost everybody that sells the Turnigy battery packs on-line gets bad reviews for delayed shipments and other problems.
Unless you are willing to spend big bucks to buy from a reputable vendor like Ping batteries in China, you are probably better off building your own battery packs like Deacon.
If you buy a battery pack from a vendor and it arrives with a bed cell, you have to ship it back to China for service (if the pack is warranted).
The DIY battery pack builder buys extra cells so he can replace any bad cells himself in the pack without shipping delays and hassles.
When you buy the battery cells on-line at bargain prices, you are likely to receive a bad cell in the shipment. Nature of the beast.

 

[deacon]

I kind of felt that way myself... Plus you can add more amp hours to your battery as you can afford it. Since you know how your battery is build, if it consistently reads low you can take it apart and check individual cells.

Best of all you have a huge sense of accomplishment. I have tested my first nimh battery( it is only 9.5 ah so I didn't run it long for fear of overheating) it does power both the test motor 200watt and the 800 watt Bike hub motor.

I want to wait now for another set of cells so I will have almost 20ah and if the c is at least 1.4 which is the least figure I have seen, it should run fine and give me the around town range I'm looking for.

Then as I feel inclined to use the scooter I built more I will add to the range of the 19ah battery taking it to 28.5 if all goes well. I will have only about $310 at most. I'm thinking I'll buy a few extra cells to have laying around.

I also have a few sla packs around I'm going to carry them along on the tricycle just in case. When I get through with the scooter it wont have room for the sla batteries. It needs to be light anyway.

Just so you know if you are going to mix batteries you need a two way switch between them and the controller. So you can run the nimh dead then switch to the SLA not try to piggy back them.

 

[deacon]

It appears that the standing voltage of the 36volt nimh pack is 37.9 to 38.1 those are the two voltages I get after letting them sit overnight. There different nights.. The pack, when i built it using fresh cells from the factory, was 38,1. So I'm going to assume that is the voltage to shoot for when recharging and letting them rest a few hours. Once I learn how to do that successfully every time I will consider this a success.

 

[deacon]

I had a thought last night Since my charger charges at 41.5 volts and the standing voltage is 38.1 what if I added 3.4 volts of standing voltage to the pack. It would seem to me that it would be less worry about over charging the battery if the voltage input and the standing voltage was close.

I will just experiment till I get the charging times correct, then toss in a half hour now and then to bring it back up to max. So I had a few nimh aa batteries left over from the old days of experimentation.

I made two mini pack of 4 aa batteries in parallel to get the ah close to the c cells I have. The wired the two mini packs in series and added them to the end of the strings of c cells. So I should have 40.4 volts of standing energy on the pack. I doubt that I can accidentally over charge them.

The off the charger voltage for a 36volt battery is over 41 volts so it shouldn't be any big deal on the controller. I'll let you know how it goes.

 

[kevyleven007]

Good job Deacon. I thought about doing something like that but never had the guts. How's it working?

 

[deacon]

so far it has passed every test but Im waiting till I can toss together another battery so I can link them and get about 20 ahs .

It has run my test motor and the motor on my bike but I didnt have my fat butt on the bike at the time. For that I need one with the full power behind it.

I really do think this is going to work . After the next battery i will have slightly over 200 bucks in it and it will be 20ah which should have a c of a least 1,4. That should be enough to test,

I think it charges slow but I have a way to beef it up I think without buying a new charger,

Short answer is so far so good.

 

[deacon]

Every day I learn something new and that is as it should be. Yesterday it was about vampire drain on batteries.

My charing station looks like this. an extension cord with a one hour timer attached. Then two sla battery chargers each at about 41.5 volts 1.5 amps. Using both gives me 3 amps to jump start the batteries (I hope). Then there is a digital voltmeter,

The battery has (1) 41.5v 1.5am charger attached. So I found standing voltage to be about 39.8 to 40 volts consistently for a couple of days. But it kept discharging a little at a time.

The vampire discharge was the charger. It was powered down because of the timer cut off, but still plugged into the battery pack. Since I didn't use the switch to disconnect it from the battery, The battery was discharging back to the charger. Now that sounds strange, but that's what happened. The battery discharge has at least an led in the circuit and probably a capacitor or two So over a couple of days while i was doing other things that charge back line discharges about .5 volts.

Thats what I learned about the NIMH battery today.

 

[paul]

I never even thought about that when charging my electric bicycle battery's. thanks deacon.

 

[deacon]

I had no idea either. The only reason I knew was that I had a furnace problem after a day other little stuff. so Instead of topping the batteries off every day while in test mode they went three day with no attention and had dropped a full volt.

Before I went looking for a bad cell, I checked everything else, then noticed the green light burning on the charger. It was disconnected from the wall, so I threw my in line switch between the battery and the light went out.

I checked for my overnight battery voltage loss last night till this morning and noticed that it stayed up (almost) no drop at all. I know there is going to be some bleed off but it was minimal over the first night. I'm going to keep an eye on it but its interesting to note what is happened every step along the way.

Actually I read an article years ago about vampire drain in household current for instant on electronics. Just read it and forgot it.

Just one more interesting little fact. Probably wouldn't make any difference unless it drained for a week or so like that which mine would have done.

 

[deacon]

Of all things it looks like my second set of batteries for the pack has gone missing. I decided no more Chinese shipping for me. I have had trouble with small orders and last time I had the batteries go astray but they did show up.

I bought batteries from a usa supplier today. He still sold on ebay but he will be shipping from New York I think it is. It means I build with aa cells instead of c cells. They work pretty well, I have used them before. The aggravation factor is heavy, but I can make it work I'm sure. I hope I can at least test the thing once before summer.

When I get the second battery built I should have 18ah and if the batteries every show up from China I will have over 25 according to the mfg. I expect it will come out more like 12ah but we shall see.

 

[deacon]

Time for an update. I finally was able to double the initial battery pack size. Shipping from China is horrible at the moment. Things are getting lost left and right.

So I built a 9ah pack with aa batteries. I combined them and tried them out. Very poor performance. It runs the bike but at about half power. I only went a couple of hundred yard then brought it home to charge.

This morning I carried it with what I think is a full charged pack. I ran it then ran a sla pack I have. The sla pack runs the bike several rpm faster than the Nimh pack.

It feels a lot like the sla pack when it goes into sag mode. So I'm thinking shortage of amps in the pack. Either the C is only 1 and at 18ah the pack is putting out only 18amps to a 25amp motor.

Or the battery ah is inflated. I'm tending to go with this one since I had the thought to begin with. It would be a typical marketing tactic. I have another set of batteries in route to build a rated 9ah addition to the pack. It that shows a significant improvement in rpms, I will give the bike another test.

This should help if the c is 1 as i suspect, I will have a 27am pack. Which would handle it. If the ah is inflated I should be able to tell a difference with the additional batteries. Stay turned the suspense level is at decon 3