What battery capacity?

[peterjd]

Yesterday cycled a round trip of ~33miles on my old converted (modified Swytch Mk 1 kit) tourer, albeit through undulating south Leicestershire countryside, using a 5Ah Bosch type battery and a quick charger (~ 1 hour). I felt the general feel was much more pleasant than with my 10Ah bottle battery ie less weight effecting ride and steering. Yes I did also turn the pedals all the way but that is what I've wanted ie to extend my cycling into older age without too much pain

Peter

 

[matthewslack]

Yesterday cycled a round trip of ~33miles on my old converted (modified Swytch Mk 1 kit) tourer, albeit through undulating south Leicestershire countryside, using a 5Ah Bosch type battery and a quick charger (~ 1 hour). I felt the general feel was much more pleasant than with my 10Ah bottle battery ie less weight effecting ride and steering. Yes I did also turn the pedals all the way but that is what I've wanted ie to extend my cycling into older age without too much pain

Peter

So an hour of charging at a stop during your ride, at 4A for the fast charger? That's impressive range from no more than 9Ah.

 

[peterjd]

So an hour of charging at a stop during your ride, at 4A for the fast charger? That's impressive range from no more than 9Ah.

I was pleased. I've made everything as light as possible while retaining carrying capacity and mudguards. I'll admit to recharging (me) on the way back, at Wistow Garden Centre cafe (S.Leics) and being tired by the time I got back into Market Harborough. The battery finally gave out about 1/2 mile from home. By the way the battery cost just £80 some 18 months ago in Amazon - I don't see those prices now.

PS The Bosch GAL 3680 CV charger apparently produces DC at 8A at both 14.4 and 36V

 

[cyclebuddy]

produces DC at 8A at both 14.4 and 36V

I certainly don't want to dampen your spirits, but back in the day when I ran a property management company, we used Bosch 10A fast-chargers on-site to save our workmen hanging around drinking tea waiting for their tools to charge.

Without exception, all the Bosch batteries we "fast-charged" died in less than a year. Reverting back to more leisurely chargers those same make/model expensive Bosch tool batteries lasted a good few years.

But I do agree. There seems to be a preference for many to buy really large e-bike batteries, which is a lot of weight to carry if all you're doing is a shorter ride and you don't need that kind of extended range.

 

[peterjd]

I certainly don't want to dampen your spirits, but back in the day when I ran a property management company, we used Bosch 10A fast-chargers on-site to save our workmen hanging around drinking tea waiting for their tools to charge.

Without exception, all the Bosch batteries we "fast-charged" died in less than a year. Reverting back to more leisurely chargers those same make/model expensive Bosch tool batteries lasted a good few years.

But I do agree. There seems to be a preference for many to buy really large e-bike batteries, which is a lot of weight to carry if all you're doing is a shorter ride and you don't need that kind of extended range.

Hmm! I had worried, before buying, about fast chargers in general shortening battery life. Without getting too cynical one hopes Bosch may have learnt a thing or two in the latest version?

 

[Bonzo Banana]

I think one of the causes of battery fires is fast charging. I saw a video on youtube which I think was from India showing how some BMS's can't cope with high current chargers that well especially smaller battery packs.

Fast charging puts the cells under more stress, shortens their life and is more likely to cause a fire on packs with more basic construction. Also what the BMS allows and what the cells can take are not necessarily connected. You might have a BMS that takes a high current but the pack is using cheaper cells that are more limited in their charge current. Those small scooter batteries which sometimes have basic 1500mAh cells may not be able to take any more than a 2A charge safely basically 1A per cell (2 in parallel). The BMS used might allow 5A max (2.5A per cell) but the cell maximum might be 1.5A or 1.75A for charge rate.

I guess this is a much greater safety issue for smaller battery packs than larger typically.

I suppose much depends on the BMS. I could be wrong but I think BMS's are typically designed around the number of batteries in series but the parallel connection can be variable for some at least so the charging current could be just two cells or could be five cells, 5A shared by 5 is 1A but 5A shared by 2 is 2.5A.

I'm still finding my BMS feet so to speak so perhaps someone can correct my theorising if wrong.

 

[soundwave]

max charge current for a bosch batt is 6A or4A

 

[sjpt]

max charge current for a bosch batt is 6A or4A

I think OP was referring to Bosch powertool batteries, and the 6A, 4A is for their much bigger ebike batteries. If it's only 5Ah it's presumably got very few parallel strips, so would have correspondingly lower safe/sensible charging amperage. (as Bonzo Banana hinted above.)

 

[soundwave]

500w is 13.4 ah but id rater charge the batt as low as possible but they dont make the 2a charger anymore