Bosch 36V fatpacks opened up

[John in CR]

These are the konion cells inside 10s2p

Here's my version of a duct tape pack 4xBosch, before and after (see no BMS on right since
batteries are wired directly to the slot connectors for output)
The spring loaded slot is for the charger's temp sensor cutoff, and to ensure the pack is properly
seated for charging.

Cutting the cell holder open. I haven't cut myself, but please do be careful. I like
to retain some of the red cell holder for structural integrity of the pack without
wasting too much room.

They don't stack very well until you get rid of some of that excess plastic. I used
an angle grinder to make quick work of it. It can be cut off, but that's even more
dangerous than cutting them open.

Tomorrow I'm going to try running my e-motorcycle with just 6 packs in parallel. I may
only get 5-6 miles of range, but should be a lot more fun than the 180lbs of lead it replaces.
Since I'm keeping it at 36V, I plan to reconnect the charging slot to the pack for easy charging.

John

 

[Ypedal]

6 packs in paralell..

If i'm counting that right.. each " fat pack" is 5S2P so 36v3ah.. each. x 6 = 18ah

This should be good for 180 amps + !

 

[John in CR]

6 packs in paralell..

If i'm counting that right.. each " fat pack" is 5S2P so 36v3ah.. each. x 6 = 18ah

This should be good for 180 amps + !

10s2p, but yep at least 180A, though I think the VT version may sacrifice some capacity for even higher power. My duct tape pack is 2x2 for my bike, but I can easily open up the tape and rewire to parallel to give me 10p packs. All I know is that right now I'm in like Flynn, especially once my other 200+ konion cells arrive from DrBass, or should I say KingBass.

Now if I can just swing the sponsor deal with Bosch and get another 50packs from them.

John

 

[pwbset]

10s2p, but yep at least 180A, though I think the VT version may sacrifice some capacity for even higher power.

Yeah just got some VTs to play with and a capacity test yielded just over 1ah for a single cell. I don't know how old the cell is though, but that's about .4ah less than the average used V cells I've been testing.

 

[HornetB]

I think I read somewhere that these cells in the bosch packs were actually only 1.1Ah, so that makes the packs actually 36v 2.2Ah. I came across some information that suggested packs produced a while ago were 2.4Ah, making each cell 1.2Ah. But the current ones are 1.1Ah Konions.

I think I'll be buying a few bosch packs for myself anyway. Cheap way in.

Cheers, HB

 

[John in CR]

I think I read somewhere that these cells in the bosch packs were actually only 1.1Ah, so that makes the packs actually 36v 2.2Ah. I came across some information that suggested packs produced a while ago were 2.4Ah, making each cell 1.2Ah. But the current ones are 1.1Ah Konions.

I think I'll be buying a few bosch packs for myself anyway. Cheap way in.

Cheers, HB

If they're good enough for DrBass, I'm in. Plus I don't have to worry about BMS's for a couple of years, while prices come down and cells and their electronics become better. It appears that Bosch is calling these packs 2ah, but their charger only charges them up to 40.5v, so I'd assume some conservatism on the discharge end too. Even if you call it 2ah, you can get 2 new packs on Ebay for $110, shipping included. Then if you can swing that 30% Live rebate, that's only $.53/wh for high power cells good for 1k cycles and no BMS to worry about. For someone like me, who wants to keep it simple, I couldn't ask for much more. Today it took me about 2 hours to put together a sturdy 6pack, 36v12+ah approximately 11"x5"x4" that can put out 180A+, using just a #15 torx key, a strong hobby knife, and duct tape. That's my kind of electronics work.

John

 

[Tom]

Thanks John, one question I have looking at the pics is how the 10 batteries in each pack are connected 5s2p? I only see 4, 4, and 2 connected. Also, how are you charging the packs? Can you do it in parallel with one Bosch charger? Can the Bosch charger charge other configurations? I'm hoping to pull my packs apart and build a 48v solution, but not sure about charging logistics.

 

[pwbset]

build a 48v solution, but not sure about charging logistics.

If you go 14s you can use any old dumb lipo 14s charger like this one:

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=4715

51.8v nominal - 58.8v hot. That's the route I'm going anyway. 14s10p 51.8v15ah

I have the 10s one currently (42v hot - 37v nominal) and it's been great so far for my 10s4p test pack until I get more konions from somewhere.

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=4211

 

[John in CR]

Thanks John, one question I have looking at the pics is how the 10 batteries in each pack are connected 5s2p? I only see 4, 4, and 2 connected. Also, how are you charging the packs? Can you do it in parallel with one Bosch charger? Can the Bosch charger charge other configurations? I'm hoping to pull my packs apart and build a 48v solution, but not sure about charging logistics.

Tom,

Each pack has 20 cells, 10 at each end of the pack. I wish you had asked, before I got them closed back up, but I believe the 2 sets of 10 are joined at one point. I didn't really check because I plan to use mine at 36v or 72v. With them joined at one easily separable point, that gives you 5s2p or 18v in series with the other 10 which will also be 18v. That will give you the ability to easily get to 54v, while using the structure already done for you.

I don't need fast charging, so I plan to use a single Bosch charger for each 36v string of parallel packs. If it still only charges to 40.5v, then I will use a topping charger on a timer to get them to 42v. I tried using my 36v Ping charger, which gets my Ping pack to 41.5, but it charged 4 parallel Bosch packs all the way up to 45v. With A123's the same charger cut off at 42.5v. I'm not sure why that occurred, but you definitely want to oversee charging the first couple of times to make sure things run like you want.

John

 

[Tom]

Ah, got it. Yes, ideally keep the structure of the 5s2p cells intact and do some simple re-wiring to achieve 54v.

What kind of gauge wire is connecting each 5s2p group of cells? Wondering if that might be a limiting factor.

 

[John in CR]

Ah, got it. Yes, ideally keep the structure of the 5s2p cells intact and do some simple re-wiring to achieve 54v.

What kind of gauge wire is connecting each 5s2p group of cells? Wondering if that might be a limiting factor.

It's not wire, just the same tab material that connects all the cells, just folded over to put the 2 groups end to end instead of side by side. Then there's a thin separator preventing the cells from shorting end to end.

John

 

[John in CR]

Bosch charger FYI:

For six 36v packs in parallel, it took right at 1 hour to charge from the 40.5v (full charge cutoff of the Bosch charger) to the full charge of 42v with a current of 1.6A (measured current from the charger while running). If I understand correctly, a big "if", this additional charge stored about 65wh in the pack. Assuming a 1.1ah capacity per cell, the these 120 cells would give the pack a total capacity of 475wh, so the difference in charging only to the Bosch charger limit forgoes almost 14% of capacity assuming no loss to heat while charging.

John

 

[pwbset]

it took right at 1 hour to charge from the 40.5v (full charge cutoff of the Bosch charger) to the full charge of 42v with a current of 1.6A

Since these Makita and Bosch packs do not include a BMS of any kind it makes me wonder if the 40.5v full charge cutoff helps the cells remained "balanced" within a range over time. I note that in my little test pack of konions on a 37v(42v max) lipo charger I will see some cell pairs up around 4.3v and some as low as 4.15 when fully charged. I think my wiring/solder blobs/cell age/internal resistance is mostly the cause of that, but maybe the 40.5v topped off Bosch charger provides for a similar voltage variation as cells get older, but can still perform within a decent range of voltages. There doesn't seem to be any adverse effect in actual practice.

Or I'm just an idiot and babbling about nonsense... yes, that's probably it now that I think about it. Heh, heh.

EDIT: Makes me wonder if a Makita 18v LXT charger maxes out at 20.25v new in 5s. Anyone have a Makita tool setup/charger/multimeter?

 

[John in CR]

I consider DoctorBass the expert in this area. He says Konions don't need balancing, and that 4.15v-4.20v is proper charge limit, then I accept these things without further analysis. That way I can focus my efforts on the things I'm good at to maybe benefit this hobby.

John

 

[Tom]

It's not wire, just the same tab material that connects all the cells

What I meant was the wiring you appear to be using to connect the batteries in parallel. Is that your wiring or the Bosch wiring? I've peeked inside the Bosch drills at the battery connectors and the wire they were using was pretty thin. The wiring in your pics looks beefier.

 

[John in CR]

It's not wire, just the same tab material that connects all the cells

What I meant was the wiring you appear to be using to connect the batteries in parallel. Is that your wiring or the Bosch wiring? I've peeked inside the Bosch drills at the battery connectors and the wire they were using was pretty thin. The wiring in your pics looks beefier.

That's the Bosch wire.

John

 

[pwbset]

The 18650VT is stated in the RCGroups forum as having a specific charge to 4.1v/cell and not 4.2v like the 18650V. This may explain the 40.5v max Bosch charge. To be taken with a grain of salt of course... I think the person may have been thinking of the 26650VT instead, which does indeed list 4.1v max charge per Sony's press release.

Regardless with the 25% Live.com/Ebay stuff and the way you're putting these packs together duct-tape-style it's incredibly tempting to invest a few hundred bucks into these fatpacks. Don't even need to worry about welding/soldering etc. etc. Nice. Already have a 37v Lipo charger that would work perfectly. How much does your 6-pack weigh?

Ugh... keep food on the table and the heat turned on or buy new batteries... decisions, decisions. :wink:

 

[John in CR]

The 18650VT is stated in the RCGroups forum as having a specific charge to 4.1v/cell and not 4.2v like the 18650V. This may explain the 40.5v max Bosch charge. To be taken with a grain of salt of course... I think the person may have been thinking of the 26650VT instead, which does indeed list 4.1v max charge per Sony's press release.

Regardless with the 25% Live.com/Ebay stuff and the way you're putting these packs together duct-tape-style it's incredibly tempting to invest a few hundred bucks into these fatpacks. Don't even need to worry about welding/soldering etc. etc. Nice. Already have a 37v Lipo charger that would work perfectly. How much does your 6-pack weigh?

Ugh... keep food on the table and the heat turned on or buy new batteries... decisions, decisions. :wink:

The 6pack weighs just a bit less than my 36v15ah Ping pack, which weighs 11lbs. It had no problem running my electric motorcycle today. With the same controller settings but a 1/3 higher gear ratio, the 6pack climbed the hill leaving my house far better than with the 36v75ah 165lb of deep cycle lead it replaced. The motorcycle is just so much more inefficient than my bike, and slower too. It really reinforces my desire to build a heavy duty 2 wheel EV with pedals that is closer related to a bike than a motorcycle, but has the comfort and stability of a motorcycle... a beefed up downhill-like rig at a fraction of the cost by accepting the weight penalty of using some motorcycle parts.

John

 

[Ypedal]

This is what i ended up with... ( 72v 20ah LiMn)

Into the 1000$ range, DH / Freeride bikes.. stuff is incredibly tough..

 

[John in CR]

This is what i ended up with... ( 72v 20ah LiMn)

Into the 1000$ range, DH / Freeride bikes.. stuff is incredibly tough..

Nice bike. I almost pulled the trigger on an extra large frame Kona Stinky with lots of room in the triangle. The cheapskate in me just couldn't get past the $1800 for a used bicycle, then like an idiot the next week I passed on a light offroad motorcycle complete with frame, brakes, wheels and suspension that weighed only about 80lbs for just $150. I have it in my head to build my own frame from scratch out of balsa, epoxy, fiberglass and carbon fiber with built in battery box and internal wiring for everything including lights. Someday soon. In the meantime I want to stockpile cheap konions. This little 10lb pack running my e-moto is crazy!

John

 

[oofnik]

This is a very good deal...
These packs are going for as low as $54.98 SHIPPED. With Live cashback and holiday discount there's no competition.
I hope someone here snags a few at that price!

 

[dimitrib90]

I forgot the entire specs of konion. Does anyone have them? Im thinking on getting a couple of these.

 

[TylerDurden]

It really reinforces my desire to build a heavy duty 2 wheel EV with pedals that is closer related to a bike than a motorcycle, but has the comfort and stability of a motorcycle... a beefed up downhill-like rig at a fraction of the cost by accepting the weight penalty of using some motorcycle parts.

Cheap, small, heavy... but it can take a pounding:


Methods' stink is real nice and fits an adult:

 

[dimitrib90]

If I bought these packs and didnt open them, could I series and parallel them together and get a very high voltage and ah? Also if I wanted to discharge 5C, could I do that with these packs since there is no BMS to limit it?

 

[John in CR]

If I bought these packs and didnt open them, could I series and parallel them together and get a very high voltage and ah? Also if I wanted to discharge 5C, could I do that with these packs since there is no BMS to limit it?

Of course. I only removed much of the packing to make them less bulky and save a little weight. I plan to wire one of the electronics and connector tops into each 36v stack I put together. That gives me a ready made slot connection to the Bosch charger along with the status of pack charge LED indicator. I have 5 chargers, so soon I'll cannibalize one of them to see if it can be made small enough to include right on the bike. It would be nice to be totally mobile and self contained. Then just pull up next to any electrical socket and plug in.

John