48v drinks bottle battery.

[Nealh]

Expected range is looking good, charged to 50.1v or 4.175v per cell group or there about's I have only done 9 miles so far and cells are sitting at 3.925v per group. This is in PAS 1 on level terrain so 30+ miles is on the cards to lvc, PAS 1 is only 13% current supply but the increase of 23% power over 36v is night and day on acceleration. Reaching cut off cruising speed is quicker and far easier to maintain 18/19mph above the 16.7mph cut off.

 

[vfr400]

We need more people to do these sort of things. I can remember 9 years ago a guy made this carbon bike from scratch in his shed on the Gernman pedelecs forum. It used a cut down Tongxin motor as a mid drive. Where's the UK talent? The nearest we got was Cwah 's dahon Jetstream, which was pretty good considering that he didn't know how to undo a hex screw when he joined the forum.

 

[Nealh]

Finally ran this 6ah HG2 12s/2p bottle battery down to LVC today, cut out is 3.2v per cell or 38.4v for the pack.
266.4 wh and 29.6 miles equates to 9 wh per mile for simple maths.
Actual wh available will be lower as wh available will be lower due to current load.
PAS 1 with the KT is 13% of available current , at 20a that is 2.6a which gives max 5wh for my 2 cells in parallel.

I calculated the total wh available at the current load as 224wh so consumption works out at 7.6wh per mile on flat terrain with some headwinds at time, speed cut off 16.2mph with riding above this easily obtainable. Rider weight 84kg, bike hybrid 700c with 40mm tyres.

 

[Nealh]

Damn the dalygreen BMS has failed, I only mentioned them a few weeks ago as being good and reliable.
I had an issue charging today so removed the pack and checked the 12 cell groups, there are only 24 cells. 10 were 4.2v and two were at 3.94v (#3 & #6).
I measured 50v via the pack but only 3.45v with the sense wire connector plugged in, removed the sense wire connector and got 34v so somewhere the pcb has failed.

I started to raise the two low groups and so far have increased them to 4.07v,

 

[Nealh]

Sods law after ordering and hoping I found the correct size replacement last night, I had another look on AliExp this morning and it thru up different listings. I found a 12 lion bms that was smaller then the one I wanted, with a switch option and same port chargr/discharge. The sw I could place under the screw cap instead of the dc charge jack.

 

[Nealh]

Back to this little battery and still working well with the LG hg2's.
I had a hick up again with the Daly WP 12s bms failing, no battery output reading though battery read 48 odd volts when the jst was disconnected.
I have decided to ditch the Daly and won't be buying any more (though the one on my p42a battery is ok at the mo), I bought a small footprint 12 switched bms without balance from aliexp seller 'Be Much Safer'.
The bms is without balance and is tiny at 6cm x 3.2cm .
Bms 10s 36v 15a Temperature | Bms 13s 20a Temperature - Battery Accessories & Charger Accessories - Aliexpress

To augment it I'm going to add a seperate active balancer .
13s Battery Active Balancer | 12s Lifepo4 Balancer Board - Battery Accessories & Charger Accessories - Aliexpress

The active balancer operating once it detects greater then 0.1v in voltage difference.

 

[Nealh]

Having removed the defective Daly I then checked cell balance and found two were low most sitting at 3.9v but again #3 & #6 both low one at 3.72v & one at 3.76v.
Not sure if this is due to two weak cell groups or the Daly draining them.
I used the manual 5v phone charger to monitor and raise each of the two cell groups to the required 3.9v .

The new 'bms' is a same port charge/ discharge model so I had to remove the charge port under the top cap and wire in a small push button latching switch, I pre wired the switch allowing extra length on the 22awg silcone wire for withdrawing the pack.
Wiring in the new BMS is simple and needing one less wire joint , the 1+12 sense wires duly soldered in correct sequence and incremental voltage checked on the jst before connecting to the bms. The sense wires though not monitoring balance still are needed to monitor hvc & lvc.

Having charged the battery and checked voltage I used the bike for a couple of errands and then rechecked cell balance , all cells happily sitting at 4.06v so I'm hopeful the unbalance was simply down to the Daly not doing it's job correctly and then the failure.

 

[Nealh]

My active balancer has arrived but as yet I have decided not to fit it yet as the HG2's are staying pretty well balanced with the non balance 'Be Much Smarter' brand BMS.

Having charged /discharged the battery a couple more times the balance is realtively good 10 cells at 4.07v , #3 at 4.08v & #6 at 4.06v. For now I'm happy with that but will keep an eye on the pack to see how it goes. For now it is behaving better then when the Daly was used.