This might go on for a bit and be a longish read so bare with it, it is one of those places you visit and sometimes wished you could stay all day as Jimmy is a captivating talker to listen and speak with.
Visited the premises today as my brother received the email that the battery was ready, so we caught the 11.28 non stop too Victoria, 70mins later we arrived via train and tube from 3 Bridges using super off peak ticket cost £16.20 return.
Soon as we entered we were greeted by his son and the kettle went straight on, then Jimmy arrived and we spent 2.5hrs chatting (time flies very quickly in his environment) about battery tech in general and looking at all his techy gadgets he plays with.
On the shelf I noticed approx. 16 recells ready to post or be picked up plus others being packed up ready to go, also on the cluttered work spaces were several others on the go. Jimmy is like a lot of us a bit eccentric and has an inbuilt passion and knowledge for his line of work which you sense he treats as a pastime that keeps him enthused all day long. We spoke about his untidy cluttered workshop with bits of tech and batteries on the work surfaces and on the floor (just mind where you step) he loathes it when his brother and son or anyone else tidying up or touching anything as then he can't bloody find anything, this made me smile brilliant.
We were there to pick up the Khalkhoff 36v 10.4 S ped recell now 13.8a using 10s 4p config 3450mah Panasonic GA's which came to £280.
Also on my part I had taken my Swizzbee 50c S ped battery/controller compartment case along as the 7s polymer pouches cells only get me max 12 miles and if I try and fly it's only 8 or 9, Jimmy took one look and said we can do that and keep all the LG BMS and other bits of gubbings in there as well. The BMS is a nano style of an intricate board with very tiny/short sense wires, the two shunts sit on a separate small pcb on the end of the battery.
I had it in mind to discuss which cells to use and had it in mind a short list choice of several, LG HG2's, HE2's, Sam's 30Q's, Sanyo GA's and Sony VCT5/6's. I first mentioned to Jimmy that the bike is capable of drawing 40/50a with a possible 65-80a peak pulse, this I had found on the German pedelec forum and the blog/website of the author ( thank god for google translator). He had contacted Dreifels ag the original electronics supplier/manufacturer of the Swizzbee who gave him the information of the bikes controller specs. We didn't get a round to discussing batteries, Jimmy straight away had done any calcs in his head and only had one cell in mind and they were on the table in front of us and in boxes on the floor. Boston Swing cells, he quickly placed them in the compartment space available and a 7s 5p config would easily fit I would have a 26.5 ah battery that weighs 3.34 kg over 2.5 times the capacity of the pouch cells. The Swings are rated 13a discharge so good capable of the 65a in 5p guise and good for much higher peak pulse, also the internal resistance of theses cells are lower then any other cell he has. The other factor he convinced me of was the apparent cycle of 3000 charges during their life to 80% DOD which he says will out perform/last any other 18650 which at best will see up to 700 cycles to 70% of DOD.
Apparently the Boston Swings aren't meant to be welded into a pack but used in a module system to create huge multi amp power sources for larger EV's, however the module system it self is quite expensive. The cell casing ends are made of very strong metal and Jimmy had a devil of a job to get any welds to take but has a new state of the art 30K welder like a TIG and this does the job for him now, he said he used pull his hair out trying to get welds to work but now relishes the chance to weld these top batteries together.
Jimmy was in his element now and he went in to discussing how the resistance works against the battery pack and aids voltage sag, he then showed us the graphs/readout of voltage tests. First were INR32E (3200mah) reading using his preferred discharge rate of 10a the cell pack showed a sag of 1.4v, next he showed a PF ( 2900mah) pack reading the sag was about 1.2v then he showed us the Swing cell (5300 mah) pack voltage sag was less then 0.4v at 10a. As he states most manufacture claims for real world cell capacity and discharge can be misleading as often only a 0.2c discharge rate is used for bragging rights. Next was a new cell resistance test a PF cells showed 36 mOhms and a Swing cells 16 mOhms and on to why he now only uses copper instead of nickel strips, in theory he says a longer strip should have a higher resistance value. A nickel strip showed 0.6 mOhms and a longer copper strip 0.36 mOhms so adding all the resistance levels together he says can amount to approx. 10w of power loss being turned in to heat and stress.
Every cell is checked for consistent IR and voltage matched then after welding together each string is checked again and IR checked again then put through 2 charge and discharges recorded, graphed and data logged. At the table we sat at was 13s 5p pack which was nearly ready for wiring to a bms etc, a however on a recheck Jimmy noted a cells IR was not matching so he had earlier cut it out and replaced it ready to reweld.
Finally before we left a mooch around the work area saw several batteries were under construction one such battery was a 1.7k 30Q in 10s 14p config quite a beast with 140 cells 420ah and a 150a nominal rating, other oddities were a large box of new Hailong batteries from an ebike seller which have some duff cells/ strings or other internal issue in them and were awaiting repair by Jimmy.
And the important bit was for said brother to pay for his battery and the price for my battery would be about 280 as well.
It's clear to see Jimmy loves his passion for electronics and batteries, so if you live nearby or are thinking of a recell then if possible its a visit not to refuse let him know you are going or just drop in to say hi you will not be disappointed.
Visited the premises today as my brother received the email that the battery was ready, so we caught the 11.28 non stop too Victoria, 70mins later we arrived via train and tube from 3 Bridges using super off peak ticket cost £16.20 return.
Soon as we entered we were greeted by his son and the kettle went straight on, then Jimmy arrived and we spent 2.5hrs chatting (time flies very quickly in his environment) about battery tech in general and looking at all his techy gadgets he plays with.
On the shelf I noticed approx. 16 recells ready to post or be picked up plus others being packed up ready to go, also on the cluttered work spaces were several others on the go. Jimmy is like a lot of us a bit eccentric and has an inbuilt passion and knowledge for his line of work which you sense he treats as a pastime that keeps him enthused all day long. We spoke about his untidy cluttered workshop with bits of tech and batteries on the work surfaces and on the floor (just mind where you step) he loathes it when his brother and son or anyone else tidying up or touching anything as then he can't bloody find anything, this made me smile brilliant.
We were there to pick up the Khalkhoff 36v 10.4 S ped recell now 13.8a using 10s 4p config 3450mah Panasonic GA's which came to £280.
Also on my part I had taken my Swizzbee 50c S ped battery/controller compartment case along as the 7s polymer pouches cells only get me max 12 miles and if I try and fly it's only 8 or 9, Jimmy took one look and said we can do that and keep all the LG BMS and other bits of gubbings in there as well. The BMS is a nano style of an intricate board with very tiny/short sense wires, the two shunts sit on a separate small pcb on the end of the battery.
I had it in mind to discuss which cells to use and had it in mind a short list choice of several, LG HG2's, HE2's, Sam's 30Q's, Sanyo GA's and Sony VCT5/6's. I first mentioned to Jimmy that the bike is capable of drawing 40/50a with a possible 65-80a peak pulse, this I had found on the German pedelec forum and the blog/website of the author ( thank god for google translator). He had contacted Dreifels ag the original electronics supplier/manufacturer of the Swizzbee who gave him the information of the bikes controller specs. We didn't get a round to discussing batteries, Jimmy straight away had done any calcs in his head and only had one cell in mind and they were on the table in front of us and in boxes on the floor. Boston Swing cells, he quickly placed them in the compartment space available and a 7s 5p config would easily fit I would have a 26.5 ah battery that weighs 3.34 kg over 2.5 times the capacity of the pouch cells. The Swings are rated 13a discharge so good capable of the 65a in 5p guise and good for much higher peak pulse, also the internal resistance of theses cells are lower then any other cell he has. The other factor he convinced me of was the apparent cycle of 3000 charges during their life to 80% DOD which he says will out perform/last any other 18650 which at best will see up to 700 cycles to 70% of DOD.
Apparently the Boston Swings aren't meant to be welded into a pack but used in a module system to create huge multi amp power sources for larger EV's, however the module system it self is quite expensive. The cell casing ends are made of very strong metal and Jimmy had a devil of a job to get any welds to take but has a new state of the art 30K welder like a TIG and this does the job for him now, he said he used pull his hair out trying to get welds to work but now relishes the chance to weld these top batteries together.
Jimmy was in his element now and he went in to discussing how the resistance works against the battery pack and aids voltage sag, he then showed us the graphs/readout of voltage tests. First were INR32E (3200mah) reading using his preferred discharge rate of 10a the cell pack showed a sag of 1.4v, next he showed a PF ( 2900mah) pack reading the sag was about 1.2v then he showed us the Swing cell (5300 mah) pack voltage sag was less then 0.4v at 10a. As he states most manufacture claims for real world cell capacity and discharge can be misleading as often only a 0.2c discharge rate is used for bragging rights. Next was a new cell resistance test a PF cells showed 36 mOhms and a Swing cells 16 mOhms and on to why he now only uses copper instead of nickel strips, in theory he says a longer strip should have a higher resistance value. A nickel strip showed 0.6 mOhms and a longer copper strip 0.36 mOhms so adding all the resistance levels together he says can amount to approx. 10w of power loss being turned in to heat and stress.
Every cell is checked for consistent IR and voltage matched then after welding together each string is checked again and IR checked again then put through 2 charge and discharges recorded, graphed and data logged. At the table we sat at was 13s 5p pack which was nearly ready for wiring to a bms etc, a however on a recheck Jimmy noted a cells IR was not matching so he had earlier cut it out and replaced it ready to reweld.
Finally before we left a mooch around the work area saw several batteries were under construction one such battery was a 1.7k 30Q in 10s 14p config quite a beast with 140 cells 420ah and a 150a nominal rating, other oddities were a large box of new Hailong batteries from an ebike seller which have some duff cells/ strings or other internal issue in them and were awaiting repair by Jimmy.
And the important bit was for said brother to pay for his battery and the price for my battery would be about 280 as well.
It's clear to see Jimmy loves his passion for electronics and batteries, so if you live nearby or are thinking of a recell then if possible its a visit not to refuse let him know you are going or just drop in to say hi you will not be disappointed.
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