Bosch 36V fatpacks opened up

[Doctorbass]

How are the batteries running? What kind of distance and speed are you getting, and what voltage? thx- I'm planning on doing pretty much the exact same thing as you, and a bit of info could help in the planning

Every of the 1.3Ah cells inside give around 3.75Wh max of energy. at 35km/h you usually need 15Wh/km no pedal...

so with 4 of these cells tou go 1KM

one fatkpack have 20 cells so thst's 5km no pedal at 35km/h

Doc

[Doctorbass]

These cells are the 18650VT and have 1.3Ah 3.7V nominal and 4.1-4.2V max charge

Charging them to 4.3 will decrease their life by a factor of 3 according to the Sony spec sheet so pay attention guys..

the recommanded voltahe for charge is 4.1V and not 4.2V.. charging to 4.2V will just a bit reduce the charge time and increase the capacity for around 5%...

compared to what is positive inn that 4.2V cahrge method i think that does not worth.

4.1V is safe. and will preserve their life cycle.

it exist two model of these sony Konoin cells: the V and the VT

The V have more capacity (1.5-1.6 Ah) but have a bit less max current... 15A max per cell
The VT have more capacity (1.3Ah) but have a bit more max current... 22A max per cell.

The max charge current on the V is around 3A recommanded and max 5 (I acheived that but it reduce a bit the cycel life)

On the VT it is 20% more.


the V have around 5Wh per cell and the VT have more 3.75Wh

The recommanded cut voltage is really 3.0V.. dont go lower. (30V min for the fatpack)

So that fatpack have 44A max at around 34V( take account of the V drop) full charge

that is 1500W max during short time.. but i would recommand using them at 5A continus max per cell so 10A per fatpack... and you should get around 10A x 38V = 380W per pack continuous power

Doc

Doc

[theyerb]

Thanks for the great info, Doc I'm gonna try to keep my cells in that voltage sweet spot, 3-4.1v, from now on.

[RealPeterPan]

Thanks Doc.
That was a good summary about the konions.
I read all the other posts about them but to have it all in one always helps the one of us who don't natively think in electric to understand

But what I still didn't get:

Can you charge these green babies with a regular SLA smart charger like this one:?

http://www.conrad-int.com/websale7/?mallid=websale&shopid=conrad-int&subshopid=int&act=product&cat_index=SHOP%5fAREA%5f14724%5f0502152&prod_index=510141

There are more detailed specks in the "multilingual instruction" link but here is a short version:

End charge voltage: 41.4V
Charge current: 6.4A +- 7%
Characteristic: I/U/U
And a picture of course:


I know the current is a bit high but should be alright if I charge more than one fatpack at the same time right?!

What I'm also wondering about is the actual price for the fatpacks.
Is it even reasonable for the sellers anymore?
Compared to dewalt they are less than half the price now.
They are actually coming in the price range of SLAs already.
Even without considering the lifetime.
How is that possible so suddenly?

Regards Sven

[theyerb]

Sven-

Maybe not quite *approaching SLA- I can get 220wh of SLA for $30 whereas 220wh of these Fatpacks would cost me $130- but they are getting pretty cheap compared to other packs.

Bosch might be taking a loss on the batteries to entice customers to buy their tools. The old "give 'em the razor for free and then charge 'em like crazy for the blades"- except the other way around.

My SLA charger overcharges my packs to over 43v, but maybe the above one is different.

[theyerb]

Hey Doc,

As I stated earlier in the thread, I accidentally let these Bosch packs charge up to 43.5v on two occasions using my old SLA charger. What sort of affect do you think this would have on the batteries?

Also, does anyone know where I can find a 41v lithium ion charger?! I've been looking around for a while, and still haven't found one that will suffice. Maybe I'm not looking hard enough...

[gmouchawar]

Here is a suggestion for those who are using SLA chargers that go up to 43V. By adding diodes in series with the charger you can reduce the voltage.
Every diode will reduce it by 0.6V. So by adding 2-4 of them you get close to the ideal voltage. You still have the burden of turning the charge off when charging is done buy at least it will go to the correct voltage.

[pwbset]

Also, does anyone know where I can find a 41v lithium ion charger?!

I've used this one from batteryspace.com for 10s LiMn and it works fine. It does take the string to about 41.8v so that's still a little high for "VT" cells, but not as bad as 4.35v/cell.

As mentioned maybe this and a diode and you're right around 41v and not having to worry about it.

http://www.batteryspace.com/index.asp?P ... rodID=4211

[Russell]

Inspired by this thread I ordered a set of 3 Bosch Fatpacks from eBay.

The price: $135 delivered less $16 (12%) Microsoft Live Cashback = $119

They arrived today and here they are:

Three little fatpacks

Bosch 002.jpg (91.06 KiB) Viewed 2100 times

They measure 6.17"L x 3.74"W x 2.92"H (157mmx95mmx74mm) and weigh in at 2 lbs 11 oz (1.215 Kg) each.

They all measured 35.9V on my cheap multimeter. That seems rather low but at least they are all the same.

Much of this info is already in the thread but I'll attempt to add some things and post different pictures.

Bosch 005.jpg

Starting disassembly

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I'll be assembling my pack much the same way that John did however I'm going to try to do it with less work

Instead of grinding which is quite messy I cut things out whenever possible.

Lots of vertical cuts then snip the pieces out

Bosch 013.jpg (71.86 KiB) Viewed 2097 times

Cut the top pieces off with a hacksaw blade

Bosch 015.jpg (89.93 KiB) Viewed 2090 times

Applied some RTV and strapped them together

Bosch 017.jpg (77 KiB) Viewed 2093 times

The size has shrunk a good bit and the weight is down from just over 8 lbs (3.65Kg) to a little over 6 1/2 lbs (3Kg).

Wires dressed with clamps

Bosch 018.jpg (90.3 KiB) Viewed 2084 times

Parallel harness made up using every last one of my Anderson connectors

Bosch 020.jpg (86.67 KiB) Viewed 2108 times

Size comparison with my 36V/9Ah SLA pack in bag

Bosch 022.jpg (77.97 KiB) Viewed 2070 times

That's as far as I got today. I have a Lithium charger on its way but in the meantime I used my SLA charger to bring the pack up to 41.5V. Judging by the 4.815Ah the WU meter said the pack took they were pretty well discharged.


-R

[Doctorbass]

Nice Job Russell !

This is a nice cheap Diy Lithium manganese Battery exemple! you have 3.7V at 1.1Ah (1.3Ah theorical) per cell so you get 6.6Ah to 7.8Ah at 37V for 135$ without bothering with Balancer BMS !! =)

Oh.. this is normal that the battery are not fully charged even though they are brand new! The storage Ah is normally recommanded to be around 40 to 60% to preserve the cells..

They stress if they are kept too long period at 100% charge.. like many lithium cells.

Doc

[Russell]

Nice Job Russell !

This is a nice cheap Diy Lithium manganese Battery exemple! you have 3.7V at 1.1Ah (1.3Ah theorical) per cell so you get 6.6Ah to 7.8Ah at 37V for 135$ without bothering with Balancer BMS !! =)


Doc

Thanks Doctorbass though I got to thinking it probably would have been even easier if I had simply taken off the tops, brought out the wires and strapped the three toolpacks together Oh well.

One question for you; is the 7.8Ah available when the 3 packs are charged to 4.2V/cell for 42.0V total?

The LVC on my Bafang 15A controller is set to 31.5V so how much capacity do you think I'll have if I charge the pack to 41.5V and discharge to 31.5V?

The weather is awful here so I can't ride to check it out.

-R

[Russell]

Completed the pack...for now anyway.

I removed the Andersons from the negative side and hard-wired those connections which made for better harness routing. I can still isolate individual packs if need be with the red disconnects. I then cut some sound padding I had leftover from a entertainment center PC and applied it to the sides.

Finished size: 6.5"L x 5.7"W x 3.5"H (about 4"H to clear wires)

Bosch 026.jpg (90.08 KiB) Viewed 1963 times

Finally I (temporarily) put the whole thing in an 8"x6"x4" cardboard box which drops right in the rear trunk bag in place of the SLA pack. The finished weight is 7 lbs compared to almost 18 lbs for the SLA's

Bosch 034.jpg

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I noticed that the no load speed with the Bosch pack at 41.5V is 0.9 mph higher than the SLA pack right off the charger which should raise my top unassisted speed to 17.0 mph Hey I'll take every little bit I can get.

Now I just need the weather to improve to get out and test it.

-R

[John in CR]

Nice Job! Welcome to the Konion Team.

John

[theyerb]

Yah, some great info, Russel. I have been using just two fatpacks on my ebike with excellent results. I just bought a third battery for extra distance and current capacity. Team Konion all the way

[ad3pt3]

I have been planing to make an ebike for two weeks now and have been trying to learn as much as possible from all the forums. I came across these Bosch packs and they seem to be a great price and provide good performance. I like the fact that they have a high c rating vs other packs and are very cheep.

I was wondering if it were possible to link six of these Bosch packs together to get a 37V 14aH pack? I would use the Anderson connectors and keep it similar to what Russell did. If so, what would be the best charger for this pack? I would like to charge them all at once.

Thanks for your help,



Ad3pt3

[theyerb]

Search ebay for "36v Universal Charger." Also, preferably a "smart" charger. You don't want a 36v SLA one!- they will actually charge it up to 44.5v rather than the 41.1v or so that you want. Here's an example of one I found on ebay:

[url]
http://cgi.ebay.com/Universal-Smart-2.0 ... dZViewItem[/url]

Charging 6 in parallel should be fine. An epic battery pack! Keep us posted.

[John in CR]

Yes 6 will make for a nice pack. For charging you might think about just getting the Bosch charger. Then you could leave the slot connector on one end of your pack, maybe even include the status of charge indicator. It would probably take 6hrs for a full charge, but slow charging and the more conservative charge level of 40.5V will make them last longer.

John

[D-Man]

Completed the pack...for now anyway.

I noticed that the no load speed with the Bosch pack at 41.5V is 0.9 mph higher than the SLA pack right off the charger which should raise my top unassisted speed to 17.0 mph Hey I'll take every little bit I can get.

Now I just need the weather to improve to get out and test it.

-R

What charger are you using? Does each pack have a fuse or are you using one? I am curious as to what voltage the Bosch pack will stay at under load and for how long. Keep up the good testing. My sla's are pretty worn out.

[Russell]

Completed the pack...for now anyway.

I noticed that the no load speed with the Bosch pack at 41.5V is 0.9 mph higher than the SLA pack right off the charger which should raise my top unassisted speed to 17.0 mph Hey I'll take every little bit I can get.

Now I just need the weather to improve to get out and test it.

-R

What charger are you using? Does each pack have a fuse or are you using one? I am curious as to what voltage the Bosch pack will stay at under load and for how long. Keep up the good testing. My sla's are pretty worn out.

Today I went on a test ride and got 6.085Ah (224Wh) from the 3-pack. I started the ride at 41.46V and ended after 25.50 miles when I hit the controller's LVC of 31.5V. The resting voltage was just over 34.0V at that time.

I just finished charging the pack using a 36V SLA charger. I monitored the recharge with a Watts-Up meter and disconnected power when the voltage hit 41.90V/6.051Ah/234Wh. The voltage immediately dropped to 41.70 and a few minutes later was 41.60. It should stabilize near 41.50 shortly based on the last time I charged it. The Li-Ion charger I have coming shold be preset from the vendor to stop and hold at 41.50V so I won't have to overshoot to get the voltage I want.

I left the 60A fuses that were hard-wired in the red leads just because it was convenient to do so. I installed an in-line fuse holder for the pack as a whole with a 25A fuse. The pack is currently used with a 250W Bafang motor and 15A controller. See more details here; http://www.endless-sphere.com/forums/viewtopic.php?f=6&t=8579#p146545

-R

[theyerb]

Holy cow- 25 miles!

[Russell]

I can never leave well enough alone so of course after assembling the battery pack and going on one ride I just had to take the pack apart and rebuild it. I broke it down (the RTV came off easily) and then installed the heavy rubber end panels. I removed the in-line 60A fuses since now they were in the way and I still had the 25A fuse for the entire 3-pack. Then I went crazy with the hot glue gun and the finishing touch was a top cover cut from a Lean Cuisine tray. The end blocks are RTV’d together and the whole pack is taped with electrical tape though that will be replaced with something stronger. The end result is the pack grew in size to 7.4”L x 6.2”W x 3.9”H and the weight increased by 11 ounces to 7 lb 6 oz (as shown below) or 7 lb 11 oz in the cardboard box, which is no longer needed for protection, but which I still used just because it fits so nice and snug in the rear trunk bag.

Rebuilt Fatpack 3-pack

Bosch 040.jpg (84.61 KiB) Viewed 1905 times

Today's ride results:

Distance: 32.2 miles (51.5km)
Average speed: 16.6 mph (26.6kph)

Amp-Hours used: 6.216
Watt-Hours used: 229.8
Min Volts: 31.63


Compared to the longest ride with the 36V/9Ah SLA pack the Fatpacks delivered 14.8% more Amp-hours, 18.6% more Watt-hours and did it with a 58% reduction in weight though volume is comparable (the fatpacks are fatties ).

-R

[D-Man]

So a 10 volt drop in overall voltage for this 36v Bosch lithium battery. So much for the flat discharge curve. These are basically like sla's minus the weight. Guess you got to aim high. I'd get one more Bosch pack and make a 2s-6p Booster pack to make up for the drop in voltage. Then get a charger at batteryspace for $20 bucks.

[theyerb]

How one earth are you getting over 30 miles on just 3 batteries?! I only get about 6 on two batteries And my 18ah of lead only gets me 20 miles.

[Russell]

So a 10 volt drop in overall voltage for this 36v Bosch lithium battery. So much for the flat discharge curve. These are basically like sla's minus the weight. Guess you got to aim high. I'd get one more Bosch pack and make a 2s-6p Booster pack to make up for the drop in voltage. Then get a charger at batteryspace for $20 bucks.

They pretty much follow the standard discharge curve for lithium batteries (see here: http://www.endless-sphere.com/forums/viewtopic.php?f=16&t=9268&p=143247#p143247 ) which is well over 1V/cell and not flat at all. In fact the standard discharge curve very much resembles the discharge curve of lead-acid just with a higher working voltage across much of it. I do find they are stronger than my SLA pack especially for the first half of my rides.

-R

[Russell]

How one earth are you getting over 30 miles on just 3 batteries?! I only get about 6 on two batteries And my 18ah of lead only gets me 20 miles.

The reasons are simple:


Low power Bafang geared motor w/top unassisted speed in low 17 mph range. Speed takes a lot of energy.

15A peak controller

I avoid using full throttle...most of the time.

Motor freewheels so it adds negligible drag. The bike rides just like it did before except for the added weight.

I started with a good quality bike that fits me well.

I ride at lower speeds than most e-bikers but a little higher than I could do on the same bike without the motor assist.

I pedal all of the time

Hills around here are generally limited to 4-6% with most terrain fluctuating in the 1-2% range.


If I used JUST the battery I suspect my range would be limited to maybe 10-12 miles.


-R