Bosch 36V fatpacks opened up

[TPA]

Just as suspected. I took a long ride today, with both the CA and WU connected.

CA reports 11.71Ah used
WU reports 11.23Ah used

A ~4.5% difference Which means one or both meters are not accurate. I tend to suspect the WU meter for the majority of it.

However it reported 11.25Ah recharge, so it is consistent.

These Bosch packs are bullet proof.

[docnjoj]

+1 for Fatpacks!
otherDoc

[yoyoman]

I found my SLA charger that didn't have an XLR adapter, and I started charging a fatpack that was down to 1.4V. In less than a minute, it was already up to 5V. In just a few minutes it was already past 20V! At that point, my Bosch charger accepted the batteries. I wonder at what point it will allow you to charge. It defnitely didn't like them at the 1.4V or the 5V.

My ride to work uses about 2Ah. Having taken these guys down to the lower depths, do you think enough of the 4.4Ah will still be usable for my ride?

[TPA]

I have had no noticeable loss in capacity since my incident.

[docnjoj]

As of today the "buy it now" price for Bat836 Fatpacks is 90 bucks! That is gettin' to be a bit high when it comes time for replacements. Lipo is looking better and better.
otherDoc

[yoyoman]

yeah, the price has gone up. I saw a steal at $70 shipped yesterday, so I had to buy it! How ironic that I was able to bring my 2 packs back to life on the same day.

[veloman]

I guess I got a decent deal on them when they were at 70/75 shipped. I would not pay more than that.

Lipo is a fraction of the cost, just more hassle with charging/balancing.

[yoyoman]

factory stock is so simple, so I love them. if only the charger wasn't so big!

[John in CR]

factory stock is so simple, so I love them. if only the charger wasn't so big!

The chargers aren't so big once you get the cover off. Here's one without the housing next to one still in the original housing.

Bosch charger no cover.JPG

(21.76 KiB) Downloaded 142 times

[veloman]

Wow, thanks for that pic! I think I'm going to take the cover off and make my own little covering for it so I can transport it easier on the bike.

[John in CR]

Wow, thanks for that pic! I think I'm going to take the cover off and make my own little covering for it so I can transport it easier on the bike.

You're quite welcome. Those 2 heat sinks get very hot, so be sure to ventilate it. The included centrifugal fan that turns on once temp is reached has a nice length of wire making ventilation pretty easy too. I have 5 of the chargers and typically just series 2 of them. I'm still up in the air about how to combine pairs in one housing for an on board charger. Stacking vertically with one inverted and rotated slightly so the heat sinks protrude within the boundary of the other, is the way to minimize the volume of 2, but side by side for minimum height will fit nicely in the lid of my cargo box. The decision I need to make soon is keep the cargo box or build a more aero cargo box that doubles as a tailbox. That will determine the form of the new charger housings. Too bad Bosch didn't include compact as a design priority, because they've proved bulletproof over a year and a half of my torture.

[yoyoman]

not a very good ride to work today after reviving the batteries. I started out with the watt's up reading 40.25, and when I got to work, it read 30.5! I could tell along the way that it was not performing well.

When I got to work, battery A read 39.5V, but battery B read 30.5. Yikes! I had charged both a few days ago until the charger stopped, which was around 40.x V.

Do these need to be reconditioned with some short rides, charges before riding them hard again? I wouldn't say my ride is that hard ...

Update: I just charged the low battery on the stock charger. It went to 40.6V in less than 30 minutes. Does this seem too fast?

[aaronski]

Hi guys,
I'm still loving my fatpacks, but I don't have enough of them. does anyone want to trade some fatpacks for a ton of lipo cells? I have 280 2 ah lipo cells, and I'd like to trade them for Konions. I'd be happy to trade 2.1 kwh for 1 kwh of konion.

[ambroseliao]

not a very good ride to work today after reviving the batteries. I started out with the watt's up reading 40.25, and when I got to work, it read 30.5! I could tell along the way that it was not performing well.

When I got to work, battery A read 39.5V, but battery B read 30.5. Yikes! I had charged both a few days ago until the charger stopped, which was around 40.x V.

Do these need to be reconditioned with some short rides, charges before riding them hard again? I wouldn't say my ride is that hard ...

Update: I just charged the low battery on the stock charger. It went to 40.6V in less than 30 minutes. Does this seem too fast?

That doesn't seem fast. If you're using the stock charger, that puts out 4A so you put in about 2AH of juice into that one pack so that's about right. I'm not sure of your configuration, but if you're running 37V and you charged the packs separately, did you put them all in parallel and give them all a top off charge before riding? That is how I charge mine if I have the time. Also, how do you have the packs wired? I have mine set up for 74V with two groups of 4 BFP 37V packs in parallel and then the 2 groups of 4 BFPs in series. All of the packs have very similar wiring to help eliminate imbalances.

Ambrose

[veloman]

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

For reference with the bosch charger, it took 90 minutes to fully charge 5 packs in parallel that had 5ah used on them. Seems faster than you'd think. It's definitely a lot faster to charge them all at once, if you have only one charger. Good reason to wire them up in parallel and keep them that way.

[jk1]

Is it possible to charge bosch fat packs, with a simple SLA 36v battery charger ? or if the final voltage is too high add 1 or 2 diodes in series ?

[ambroseliao]

Simple 36V SLA chargers tend to put out too much voltage for Bosch Fat Packs. The BFPs can go to 41.5V to 42.0V max.

[jk1]

So do you think if i tweaked the final voltage down by 2 or 4 diodes it would be ok with a standrad SLA charger ? what diodes model would i use ? its for charging 36v bat836 with a 36v sla charger

If i make the final voltage not more then 41v by puting enough diodes in or tweeking the SLA charger TRIMPOTS can i leave it on charge indefinetly ? or does it still need a timer to stop it ? isnt it the case if the final voltage of the batt is 41v and the charger is 41v then no voltage will flow henc not a problem?


If i can't use the SLA chargers easily is their any cheap off the shelf 36v Charger to suit these bat 836 batts for 240v input? i don't want to use the bosch chargers

I have been reading in this thread that these konions need a 3.0v Cutout hence for 10 cells in the fat pack thats 30v, how is this LVC cutout done in the bosch tools ? the battery has that volt meter on it what output does that give the drill to tell it to stop ?

[docnjoj]

IIRC the standard unmodified Fatpacks have an LVC at 24 volts. Mine have all been "modified" and I once drained them (slowly and accidentally) to 0 Volts. They all recovered with a few charge D/c cycles. Still the best batts out there.
otherDoc

[ambroseliao]

So do you think if i tweaked the final voltage down by 2 or 4 diodes it would be ok with a standrad SLA charger ? what diodes model would i use ? its for charging 36v bat836 with a 36v sla charger

If i make the final voltage not more then 41v by puting enough diodes in or tweeking the SLA charger TRIMPOTS can i leave it on charge indefinetly ? or does it still need a timer to stop it ? isnt it the case if the final voltage of the batt is 41v and the charger is 41v then no voltage will flow henc not a problem?


If i can't use the SLA chargers easily is their any cheap off the shelf 36v Charger to suit these bat 836 batts for 240v input? i don't want to use the bosch chargers

I have been reading in this thread that these konions need a 3.0v Cutout hence for 10 cells in the fat pack thats 30v, how is this LVC cutout done in the bosch tools ? the battery has that volt meter on it what output does that give the drill to tell it to stop ?

I don't know what the SLA charger's output V is so can't say if diodes will drop it enough. I don't know if you need a timer or not. I wouldn't leave it on your batteries indefinitely. If the charger is "smart" enough. You may be able to get away with leaving it on, however, I'd definitely check to make sure it goes into trickle charge mode.

There used to be one from Tenergy that was perfect for the BFPs, however, they are no longer readily available. All-battery.com used to sell them, but I haven't seen them come up in a long time. They had a clearance sale about a year ago and they haven't been restocked since. Of course, you could use a Meanwell 48V charger trimmed down to 41.5V or a MW 36V turned up to 41V. These are easy to modify the final voltage and they aren't very expensive.

http://www.all-battery.com/chargersforl ... dpack.aspx

Ambrose

[docnjoj]

I don't know if Bosch 36 volt chargers went up proportionally with the Fatpack price increase but each of my Bosch chargers was about 30 bucks and charges to 40.5 volts without fail.
otherDoc

[ambroseliao]

Unfortunately, they have gone up in price also. It is possible to bid on one that comes up and win it for a lower price than the going "Buy It Now" price.

I just looked and there's one available for $97!!!!!

http://cgi.ebay.com/Bosch-36V-Litheon-1 ... 1896wt_981

I believe I paid $45ish for mine off of the 'Bay.

Ambrose

[docnjoj]

Yuck! A.L.! That really sucks! I can't believe that they could have gone up double in less than 2 years. Bosch tools are good but not that good!
otherDoc

[ambroseliao]

It's the law of supply and demand. With demand so low, price goes high!

Meanwell power supplies are looking better and better.

Ambrose

[ambroseliao]

If you look at completed auctions, there was one that sold for $71 on the 11th. Not a great improvement, but they are still available, at least?!?

Ambrose