Bosch 36V fatpacks opened up

[XRuss]

In need of a fatpack Bosh BC830 36V charger? Here is a good price on one. Maybe check it out.

http://www.amazon.com/Bosch-BC830-36-Volt-Battery-Charger/dp/B000JTDSRE

 

[stiffi]

In need of a fatpack Bosh BC830 36V charger? Here is a good price on one. Maybe check it out.

http://www.amazon.com/Bosch-BC830-36-Volt-Battery-Charger/dp/B000JTDSRE

I already bought this. I tried to point people there in my post about the rest of my pack. Must have gotten buried. I bought my packs from amazon to for $49.99 a piece. Great Deal.

 

[lcyclist]

I purchased 4 fatpacks. All are 35 volts but one was 7.4 volts. Defective? Bad?

I once had a brandnew fatpack that read 0V. Yes 0V. The bosch fast charger won't recognize it and it won't charge.

Instead of getting a warranty replacement, I just had to open it up. Internal fuse was good, but each cell (2 cells in parallel) are all reading 0V.

So, what I did was to put a constant voltage, constant current 36V, 1A to charge it up to 32 V, then use the bosch charger to finish charging to 41V.

What I found was that the cells/pack will not hold a charge unless the voltage is charged over 32V; what I mean by that is that if I charge it to only 30V, the terminal voltage will slowly discharge to 0V. After it has been charged to 41V, the terminal voltage stays at 40.6V, even after 2 weeks on the shelf.

So far the fatpack is used for my drill and I have about 6 charge cycles on it.

 

[stiffi]

Stiffy,

Yes you could do everything without even opening the packs up.

Could you help explain how exactly to parallel the packs without opening up the packs? I received them today, and so far I've just stairing at them figuring out how best to start.

thanks

 

[pwbset]

Could you help explain how exactly to parallel the packs without opening up the packs? I received them today, and so far I've just stairing at them figuring out how best to start.

Personally I'd just open them up if you don't care about returning them or warranty etc. You'll lose a lot of the bulk and some of the weight and it's really easy at that point to just connect all the blacks and all the reds in parallel etc. HOWEVER... it'll also be a lot easier to short the snot out of yourself so if you're not sure what's up you may just have to get some spade connectors and rig something with the intact packs.

EDIT: And by the way page 5 has all the info you need to keep going... look at what Russell did...

http://endless-sphere.com/forums/viewtopic.php?f=14&t=7569&start=60#p145791

 

[John in CR]

I saw $46 including shipping today on Ebay. Imagine if you got lucky and snagged that 30% Live cash rebate. Another year and these kind of prices will be high. Just look at the 50% or so that lithium batteries have come down in the last 12-15 months. The future is definitely bright, especially when you consider the 10X energy & power densities that the researchers are reporting.

John

 

[stiffi]

Could you help explain how exactly to parallel the packs without opening up the packs? I received them today, and so far I've just stairing at them figuring out how best to start.

Personally I'd just open them up if you don't care about returning them or warranty etc. You'll lose a lot of the bulk and some of the weight and it's really easy at that point to just connect all the blacks and all the reds in parallel etc. HOWEVER... it'll also be a lot easier to short the snot out of yourself so if you're not sure what's up you may just have to get some spade connectors and rig something with the intact packs.

EDIT: And by the way page 5 has all the info you need to keep going... look at what Russell did...

http://endless-sphere.com/forums/viewtopic.php?f=14&t=7569&start=60#p145791

Okay, I think I'm getting closer.

So, if I attach my own wire with spade connectors to the existing terminals, How do I charge the entire pack?

I bought the stock Bosch charger. If I wire the packs together, without opening them up, How can I get the Bosch charger on there? A wire would be in the way, from my parallel job.

 

[TPA]

I don't remember seeing here what the maximum charge rate for these packs is.


Does anyone know?

 

[John in CR]

I don't remember seeing here what the maximum charge rate for these packs is.


Does anyone know?

I don't know about maximum rate, but the Bosch chargers put out over 3.5a, or well over 1c, so you can fully charge your deleted pack in under an hour. Buried in other Konion threads Doc Bass mentions max charge and discharge, though that may be only for the US18650V cells, which have slightly lower max rates than these VT's. Conservative is how you want to run the Konions, then they should outlast the 500-700cycle life expected in tool use.

If you're interested in super fast charging, then A123's or high rate LiPo's are the way to go. If you're after maximum cycle life and believe the tab welds, bms, and packaging can outlive the cells themselves, then LiFePo4 is the way to go at this point. If you're looking for 2-3 years assuming 1 full cycle per day and want relatively high power in a very safe package that you'd have to almost intentionally damage to mess them up, and relatively high power cells, along with probably the best price per wh, then I challenge anyone to come up with a better choice than these Bosch fatpacks.

John

 

[TPA]

I asked for the info, and found docs answer and I'm "republishing" it here for anyone interested.
.
.
.

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

 

[RoughRider]

in the FATPACK are 20 of the smal(US18650VT with 1,6Ah) Sony Konions and not the bigger ones, US26650VT ist that right?

in one fatpack are 20cells, is that right?

 

[pwbset]

in the FATPACK are 20 of the smal(US18650VT with 1,6Ah) Sony Konions and not the bigger ones, US26650VT ist that right?

in one fatpack are 20cells, is that right?

Yes, correct.. 20 18650VT cells in 10s2p and they are realistically @ 4.1v/cell 1.1ah not 1.6ah... might squeeze 1.3ah @ 4.2v/cell, but they won't live long. I've got VTs mixed with Vs in my pack by accident and charging to 4.2v/cell so I'll let you know how long they last. :wink:

 

[John in CR]

in the FATPACK are 20 of the smal(US18650VT with 1,6Ah) Sony Konions and not the bigger ones, US26650VT ist that right?

in one fatpack are 20cells, is that right?

Yes, correct.. 20 18650VT cells in 10s2p and they are realistically @ 4.1v/cell 1.1ah not 1.6ah... might squeeze 1.3ah @ 4.2v/cell, but they won't live long. I've got VTs mixed with Vs in my pack by accident and charging to 4.2v/cell so I'll let you know how long they last. :wink:

1.1ah is way low. Maybe that's the number if you run your packs at maximum current, but otherwise the VT match the V's almost exactly in a 6/5 relationship. Depending what source you look at V's at 1.5ah-1.6ah, so the VT's at 1.25-1.33ah. I know this because one of my packs is made up of 6 fatpacks in series with 10p7s 18650V's and the two segments stay in almost perfect balance. The couple of times I've had to nudge them back into balance was to add a bit more charge to the 7s segment, not the Bosch's.

To me it's a moot point. If you're in question about capacity, just buy and extra pack to 2. Your batteries will live longer and have greater capacity over the long haul that way anyway. That $50-$100 is going to give you piece of mind for a year or two, and then better, cheaper, smaller, long-life batteries will be readily available. Just a year ago we were paying double the going rate now.

John

 

[liveforphysics]

Sold out now , but here they are at $46 shipped.

http://cgi.ebay.com/Bosch-36V-Litheon/Lithium-Ion-Fat-Pack-Battery-BAT836_W0QQitemZ120382096663QQcmdZViewItem

$0.51/Wh for a very safe battery. Not too shabby.

Slightly cheaper than the group-buy cost on Headways cells, and these cells have a lot of advantages, like rapid charging.

Due to free shipping, it's actually cheaper per Wh than LiPo. Of course it's also twice the weight and size for a pack with the same energy, but it has the nice advantage of being a totally safe chemistry.


If you aren't afraid to build a pack, it's a pretty tough deal to beat IMO.

 

[stiffi]

I asked this before without much luck, so I thought I'd try again.

Can anybody recommend a way to connect the packs in parallel while leaving on one of the slot connectors, so I can use the stock Bosch Charger with the slide terminals?

thanks.

 

[John in CR]

I asked this before without much luck, so I thought I'd try again.

Can anybody recommend a way to connect the packs in parallel while leaving on one of the slot connectors, so I can use the stock Bosch Charger with the slide terminals?

thanks.

Just do exactly that. Don't cut the board off the end pack and just splice the other + and - wires from the other packs into that one. Another way (and how I use mine) is to use one of the boards to slide right into and stay with the charger, and connect all of the packs in parallel with a single charging connector to go to the + and - of the board. With only 2 wires to mess with for each pack, zero electronics knowledge is required and all you have to to is get the polarity right.

John

 

[John in CR]

If you aren't afraid to build a pack, it's a pretty tough deal to beat IMO.

As long as you stick with 36V or multiples thereof, it's the easiest pack you'll ever build and really just a matter of soldering the leads together, which even those with caveman soldering skills like me can pull off. You can use portions of the original pack for a tough and strong structure, and don't have to do any tab welds or soldering directly on the cells, since it's usable and quite compact after you shed some of the protective cover needed for powertool use.

John

 

[stiffi]

I asked this before without much luck, so I thought I'd try again.

Can anybody recommend a way to connect the packs in parallel while leaving on one of the slot connectors, so I can use the stock Bosch Charger with the slide terminals?

thanks.

Just do exactly that. Don't cut the board off the end pack and just splice the other + and - wires from the other packs into that one. Another way (and how I use mine) is to use one of the boards to slide right into and stay with the charger, and connect all of the packs in parallel with a single charging connector to go to the + and - of the board. With only 2 wires to mess with for each pack, zero electronics knowledge is required and all you have to to is get the polarity right.

John

So you are talking about taking off the top, connecting the + and - wires to the red and black, while still attahced to the board, right? Doesn't that make for a slighltly loose connection to the bosch charger?

Also, when you did this, did the board charge indicator reflect the charge for the whole pack as far as you could tell? Or just the last battery?

 

[John in CR]

I'm actually running 2 bosch chargers in series for an 81v auto cutoff. One has the board with the plastic slot housing slid in and connected to the charger. The other is just the board, which yes is kinda loose on the charger. The boards stay with the chargers, so the charge indicators just cycle and let me know they are working. If you left the bottom of one pack intact and just connected all your +'s and -'s to it, then I'm sure the charge status would be for the pack as a whole, since in parallel, they are tied together and are at the same voltage. The indicator is similar to those on throttles with a status of charge indicator LEDs, but this fancy one cycles while charging.

John

 

[pwbset]

1.1ah is way low. Maybe that's the number if you run your packs at maximum current ... V's at 1.5ah-1.6ah, so the VT's at 1.25-1.33ah

Respectfully disagree and I'm not trying to be contrary, but these things are uber-important to me or else I end up juiceless deep in the woods on the side of a mountain and I don't like that. :wink: Clearly with these reject pack cells "your mileage may vary". All my V cell CBA tests yielded about 1.35ah/cell @ 5C, which is my average consumption, and according to DocBass a VT @ 4.2v is theoretically ~1.3ah and can handle 5C more gracefully than a V anyway so I'm not really worried about my cell mixing mistake for now. "Close enough". My 8p mixed V/VT pack should be good for at least 10.4ah @ 4.2v-1.3ah/cell and I'm slurping about 7.5ah during my commute so DOD works... should at least last through my summer commute season (100-120 cycles) at which point I'm sure I'll want to build a new pack for next summer anyway.

Again I'm not trying to argue, but I guess my point is I wouldn't count on V 1.5ah/VT 1.3ah unless they are brand spanking new and/or you're drawing 1C or less and/or you're over volting a bit. Just my .02.

 

[Russell]

The Fatpacks are rated at 2.2Ah each which means the cells are 1.1Ah since they use 20 of them in each pack. The most I've gotten out of my 3-pack is 6.4Ah when run down to the controller's 31.5V LVC.

-R

 

[John in CR]

pwbset,

Please find me some used Bosch packs to pick up...we're talking about new only. If you're worried about getting stuck in the woods, buy more batteries.


Russell,

I like that Bosch rates their pack conservatively. Too bad all makers of batteries don't do the same.

John

 

[Russell]

pwbset,


Russell,

I like that Bosch rates their pack conservatively. Too bad all makers of batteries don't do the same.

John

John,

I'm not so sure about that conservative rating. As I stated above the most I have gotten from my 3-pack is 6.4Ah which of course is less than the rated 6.6Ah for three of the packs in parallel. The 31.5V LVC of the controller used is a bit high but the pack doesn't have much power left after 6Ah and the voltage drops quickly at that point. I'm wondering if the packs I got on eBay weren't a bit old :?

-R

 

[pwbset]

I'm wondering if the packs I got on eBay weren't a bit old :?

That's entirely possible, which may be why they are so cheap. 6.4ah to 31.5v though seems pretty bang on. Under lighter loads I was getting right around 2.2ah for my single pack taken down to 30v resting.

And John.. all due respect.. but I climb a mountain over 1,600ft vertical to get to work.. it's not as easy as just adding more batteries. Weight it a very important issue for me so I build my packs only with the AH I need. And you can't tell me those 100s of Vs you got from DocBass are anywhere near new. :wink: Anyway.. we're being silly.. I have total respect for you and what you're doing. I'm just seeing different performance issues and numbers from the cells I have that's all. If you're getting 1.25-1.35ah out of your VTs and 1.5-1.6ah out of your Vs then more power to you! I just wanted others to be aware that's most definitely not always the case is all.

 

[Ultraman]

I bought three of these a couple weeks ago from ebay. Two will charge to 41.5v, but one is holding at 32.8v and won't "take" a charge. I.e. when I hook up my ecitypower 2amp 41.8v charger it shows a green light. Do I need to take the pack apart and sort out if I have some bad cells? I've taken the board off the top and the 60a fuse off and soldered andersons on, but the plastic casing hasn't been breached. I was planning on hooking them up in parallel for 6.6ah. If I do this with the "weak" pack, is there any chance of them balancing if I then put the charger on the whole thing? Sorry if the questions are noobish, or answered elsewhere.