February 23, 201610 yr Two chargers and split the batteries for charging is no problem. 39€ per charger, 78 € in all. You only need one charger as you would seperate them from series and charge both blocks in parallel so you would be charging a 5s 32aH battery. My charger of choice would be a BC168 recommended to me by d8veh which is easiest to use and also comes with a balance board. edit: Oh just noticed you mentioned the new LiHV batteries which charge to higher volts,you will need a Lihv specific charger for those which hobbyking also sell. You still only need one though with a balance board to parallel charge them together Edited February 23, 201610 yr by awol
February 23, 201610 yr not trying to be clever, but I don't think 6S at 20.9V will give its full capacity ()i.e. 16Ah), also it may be flirting with damaging low voltage. having lived with hobbyking lipos ive been converted back to eclipse bottle batteries - it's the supervision, it's the risk of waking up to a house on fire (or trekking it around safe places outside)that doesn't feel worth it If I understand one should only take them down to 3.1 V / cell which for the pack in parallel is 37.2 V. If the controller can handle 44 V peak charge that is fine with me! I would not be charging unsupervised and not inside. I also have an alternative stocking place well out of harms way.
February 23, 201610 yr If I understand one should only take them down to 3.1 V / cell which for the pack in parallel is 37.2 V. If the controller can handle 44 V peak charge that is fine with me! I would not be charging unsupervised and not inside. I also have an alternative stocking place well out of harms way. yes I run 12S (44V) with a s12sh (from BMS battery) with a BPM 340RPM in a 20 (406) wheel and it tops out at a nice relaxed 19 to 20 mph. One advantage is controllers are cheap and one cant exactly over-discharge LiHV
February 23, 201610 yr yes I run 12S (44V) with a s12sh (from BMS battery) with a BPM 340RPM in a 20 (406) wheel and it tops out at a nice relaxed 19 to 20 mph. One advantage is controllers are cheap and one cant exactly over-discharge LiHV I mean ito current - it being something like 20S - not voltage - I tend to avoid going anywhere near 3.1V/cell because I suspect it may reduce cycles.
February 23, 201610 yr edit: Oh just noticed you mentioned the new LiHV batteries which charge to higher volts,you will need a Lihv specific charger for those which hobbyking also sell. You still only need one though with a balance board to parallel charge them together My logic is to halve charging time and have a spare charger I can eventually chuck in the bag to take with me. OK just read about parallel charging I understand now. Edited February 23, 201610 yr by anotherkiwi
February 23, 201610 yr Author If I understand one should only take them down to 3.1 V / cell which for the pack in parallel is 37.2 V. If the controller can handle 44 V peak charge that is fine with me! I would not be charging unsupervised and not inside. I also have an alternative stocking place well out of harms way. I charge indoors as I have too But I take the following precautions 1. In a open too metal box on a concrete base 2. The box has a smoke alarm 4 ft above it 3. There is a suitable fire extinguisher within 8 feet (not too close or far) 4. The packs are protected by foam and tupperware casing from puncture Always worth reiterating !
February 23, 201610 yr The packs are 10 C which is about 100 Amps constant discharge. What are the consequences of pulling up to 18 A peak: - little to no sagging? - less heat (I am pretty sure about this) - longer pack life?
February 23, 201610 yr The packs are 10 C which is about 100 Amps constant discharge. What are the consequences of pulling up to 18 A peak: - little to no sagging? - less heat (I am pretty sure about this) - longer pack life? Hobbyking are hugely optimistic regarding the power density of their lipo packs. You should derate the C rating by a factor of four to ensure a healthy battery life, low levels of heat and acceptable voltage sag. I'd also steer clear of the 'HV' variant of the Multistar packs. They're just a marketing ploy to get you to buy new chargers if you're already invested. The regular multistar packs have been proven to a degree over the last couple of years, are quite a bit cheaper and are perfect for ebike use. They even come in 20Ah 6S packs!
February 23, 201610 yr AK the folks over on the Sphere are saying that the C rates claimed by HK are ambitious, the Sphere guys reckon C rates are about 1/4 of the claimed rate. Not sure about LIHV but std lipo discharging to 3.1/3.2v is close to the cliff where they fall away very quickly, I currently set my alarms to 3.5v under load which settles down to 3.64 - 3.74 resting voltage and they appear to be staying balanced with no pack cells differing more then 0.016 volts. Edited February 23, 201610 yr by Nealh
February 23, 201610 yr Cells in a healthy lipo pack should stay balanced within a couple of 0.01v of each other if you don't discharge past the 3.65v per cell point. Not that it will matter too much if you are only using two separate packs and intend on balancing every charge. Something to think about though for those of us bulk charging at full pack voltage without a BMS! Edited February 24, 201610 yr by danielrlee
February 23, 201610 yr Two chargers and split the batteries for charging is no problem. 39€ per charger, 78 € in all. If you decide on 2xchargers there's also the cost of 2 power supplies too which has the benefit of charging twice as fast, and some cheap lipo alarms/monitors
February 23, 201610 yr The alternative to balance chargers is a BMS and bulk charger. With this solution you're left with a simple plug and forget type charging setup.
February 23, 201610 yr The alternative to balance chargers is a BMS and bulk charger. With this solution you're left with a simple plug and forget type charging setup. I would be interested in one of these, could you recommend any bms's suitable for use with lipo's which you may have used?
February 23, 201610 yr Thanks all for very useful feed back! So if I stick with 10/4 = 2.5C is that for the packs wired in series Amps? I think at 150 € I am going to play with a 10.4 Ah set up which would mean 25 Amp output at 2.5C Edited February 23, 201610 yr by anotherkiwi
February 23, 201610 yr Reading the Sphere the c rating is regardless whether serial or parallel or connected S & P, any of the 10c rating will be capable of 25amp draw or 2.5c. The thinking over their is that packs are best used paralleled in larger packs for a variety of reasons; packs less likely to get hot in use , balancing is better controlled when hooked up together, internal resistance (IR) remains lower, discharge on larger packs is kinder.
February 23, 201610 yr Author AK the folks over on the Sphere are saying that the C rates claimed by HK are ambitious, the Sphere guys reckon C rates are about 1/4 of the claimed rate. Not sure about LIHV but std lipo discharging to 3.1/3.2v is close to the cliff where they fall away very quickly, I currently set my alarms to 3.5v under load which settles down to 3.64 - 3.74 resting voltage and they appear to be staying balanced with no pack cells differing more then 0.016 volts. From my own experience they fall offthe cliff at 3.1v I set my alarms at 3.4v which with my setup gives me a mile in the tank (average)
February 23, 201610 yr Author The packs are 10 C which is about 100 Amps constant discharge. What are the consequences of pulling up to 18 A peak: - little to no sagging? - less heat (I am pretty sure about this) - longer pack life? I have run my packs as booster batteries on 36v bpm motor run at 50.4vnominal (48v mini controller at 15a) I have done so for years using various 18650 packs of various makes and models. When I changed to Lipo the lack of sag and instant torque was hugely apparent
February 24, 201610 yr I would be interested in one of these, could you recommend any bms's suitable for use with lipo's which you may have used? As hinted in my previous post, I run my lipo packs without any BMS protection, sometimes referred to as 'bareback lipo'. This isn't a setup that I would ever recommend to anyone, but is perfectly manageable if lipo is kept within certain operating parameters. If these have to be explained, running bareback is not for you. http://bestechpower.com is the goto source for BMS systems. They offer a huge range but I *think* require a minimum order quantity of two units. BMS's can also be purchased from https://bmsbattery.com/82-lipo and from Ebay/Aliexpress anongst others. I'm not however currently aware of any UK sources.
February 26, 201610 yr Yesterday I went over to youtube to check out "lipo fire". If I don't crash at 70 km/h, if I don't over-charge, if I don't discharge at 20C continuous, if I don't mess up connections at charge time, if I don't fully charge before storing... I think the risk is pretty minimum. I will not be hitting the packs with an axe or a hammer any time soon... Charge to 41.5 V, discharge alarm set to 35.5 V (from my ES reading that should allow up to 600-800 charge cycles if I balance charge every time). At home stockage in storage mode: in the oven with a smoke alarm, extinguisher on hand. I know, don't open the oven door unless things get out of hand - I was a volunteer fireman back in the day. Oh and control the quality of the packs on arrival, if there is a duff cell break one of the balance leads at the plug and send it back because HK doesn't accept returns if one cell is slightly off... That cleared out of my mind, this morning I made lots of paper models of packs (as an ex industrial design student first reflex = make a model) to see what is the maximum I can fit in the tiny triangle of my next bike. I have three options: - I could fit 1 x 20000 mAh 6S + 1 x 20000 mAh 4S in series for 20 Ah at 37 V - or 2 x 8000 mAh 6S + 2 x 8000 mAh 4S in series then parallel for 16 Ah at 37 V - or 2 x 5200 mAh 6S + 2 x 5200 mAh 4S in series then parallel for 10.4 Ah at 37 V and make two packs and swap over when first is empty - price difference is less than 10€ whatever the choice I will be setting maximum Amps to 18 on the controller so under 1C for the first, just over 1C for the second and about 2C for the third. Experts opinions on this are welcome! The battery box will be in ply because wood is what I do best. Interior will get lavish coating of M1 fire retardant paint and the ply should better insulate from external heat than some of the plastic boxes I have seen. Eventual internal heat build-up to be evacuated by a vent (Reminder: do not park in the sun).
February 26, 201610 yr When I was checking out lipo's before getting into them I also checked ytube for lipo fire. At first I was worried but then realized most were caused on purpose by misuse, a bit like a video of putting a match to a can of petrol to see what how much it would flare up. I've made up a 12s in a plastic tupaware type tub and a 10s wrapped in foam type packaging and wrapped in ducktape, with the idea they won't really get hot at the charge/discharge rates I will be doing them at, but I haven't started regularly using them yet.
February 26, 201610 yr Yesterday I went over to youtube to check out "lipo fire". If I don't crash at 70 km/h, if I don't over-charge, if I don't discharge at 20C continuous, if I don't mess up connections at charge time, if I don't fully charge before storing... I think the risk is pretty minimum. I will not be hitting the packs with an axe or a hammer any time soon... Charge to 41.5 V, discharge alarm set to 35.5 V (from my ES reading that should allow up to 600-800 charge cycles if I balance charge every time). At home stockage in storage mode: in the oven with a smoke alarm, extinguisher on hand. I know, don't open the oven door unless things get out of hand - I was a volunteer fireman back in the day. Oh and control the quality of the packs on arrival, if there is a duff cell break one of the balance leads at the plug and send it back because HK doesn't accept returns if one cell is slightly off... That cleared out of my mind, this morning I made lots of paper models of packs (as an ex industrial design student first reflex = make a model) to see what is the maximum I can fit in the tiny triangle of my next bike. I have three options: - I could fit 1 x 20000 mAh 6S + 1 x 20000 mAh 4S in series for 20 Ah at 37 V - or 2 x 8000 mAh 6S + 2 x 8000 mAh 4S in series then parallel for 16 Ah at 37 V - or 2 x 5200 mAh 6S + 2 x 5200 mAh 4S in series then parallel for 10.4 Ah at 37 V and make two packs and swap over when first is empty - price difference is less than 10€ whatever the choice I will be setting maximum Amps to 18 on the controller so under 1C for the first, just over 1C for the second and about 2C for the third. Experts opinions on this are welcome! The battery box will be in ply because wood is what I do best. Interior will get lavish coating of M1 fire retardant paint and the ply should better insulate from external heat than some of the plastic boxes I have seen. Eventual internal heat build-up to be evacuated by a vent (Reminder: do not park in the sun). I angsted over many models too - even bought cash boxes and tried to convert them: then I had an epiphany that really helped: just wrap it in fat bubble wrap and stuff it in a carrradice camper saddlebag ( I have yet to come off a bike in away that damages the saddlebag area significantly). it works great for me
February 26, 201610 yr I am reading this thread with interest, but getting bogged down with charge/discharge rates series/parallel. I have 10.4ah bottle battery 36v-250 w and new bottle battery but they have totally different connections on mounting frame. I was thinking perhaps I could use a single lipo pack and connect up to controller when 10.4 battery is depleted for a longer journey. heres where I am confused hk 6s 1600ah lipo £85 is the capacity similar to say 15ah bottle battery but I believe its 48v rather than 36v . is there a lipo pack 36v that would suite my needs and if possible exactly what would I need I am thinking its easier to carry a single lipo in frame bag /bottle cage than a bulky battery. ps do hk do jst to bullet connector leads
February 26, 201610 yr 10S = 36 V go back to the beginning and read again! so you need 2 x 5S or 4S + 6S to make a 37 V battery.
February 26, 201610 yr I angsted over many models too - even bought cash boxes and tried to convert them: then I had an epiphany that really helped: just wrap it in fat bubble wrap and stuff it in a carrradice camper saddlebag ( I have yet to come off a bike in away that damages the saddlebag area significantly). it works great for me I am going to first off build a 10.4 A pack to get the hang of things and it is going to live in one of my pannier bags in a nice IKEA plastic box for perforation protection with a bit of foam to stop the individual packs from moving around.
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