Ping Batteries in parallel query

[Citrus]

Is it possible to connect two 24v Ping batteries that each have their own BMS in parallel to give more amps and therefore more range. I have a 24v 16ah battery at the moment and was thinking about getting a 24v 8ah battery to connect in parallel and give a 24v 24ah battery. What would I need to do to achieve this if it is possible - do I need diodes etc.

 

[flecc]

It's generally not a good idea to parallel mismatched batteries, but it could be a good idea to ask Li Ping if their BMS's can stand direct connection, they may do. Alternatively, if they are charged separately and isolated by Schottky diodes when in use on the bike to deliver current it can be done.

Schottky diodes come in two suitable types, a small plastic oblong two connection package and the metal backed TO220 transistor type package with three terminals. Two of the three terminals are common anyway, so it remains a two terminal device.

Just one Schottky diode in one of each battery's line is sufficient, say one in each positive line, the + diode outputs joined then to feed the controller. The batteries' negatives can be directly joined without diodes.

Choose Schottky diodes with sufficient voltage and current capability, for example a 50 Volt 20 Amp rated one would be enough for almost all 36 volt systems, but you can choose higher values for both voltage and current if wished with no ill effect. I can't get into Maplin's components pages at the moment for some reason but they might have suitable ones, but if not, RS Components have a large range. You'll need to search down through semiconductors, diodes, etc to get down to the Schottky types.

If the batteries discharged equally in use you could find a step down in performance once the smaller one emptied and it's BMS shut off. In other words, having the two fully charged would give a slightly better performance than at present, but it could revert to the present performance once one emptied.
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[Citrus]

Thanks

Thank you flecc. I also spoke to my father today who is a retired electrical engineer, and he gave me pretty much identical advice to what you have already given me. I will contact Li Ping and see what his advice is too.

I have removed the Alien kit from my Kinesis bike and replaced it with a 500w Cyclone kit. The Alien kit suffered two controller failures, and so was unreliable for me. I have a replacement controller bought from e-crazyman to try out, but in the meantime I bought the Cyclone kit. I really like it (now) after a lot of adjustment and some heavy duty waterproofing it is now proving very reliable (well, 150 miles so far). I now know that I like the drive through the chain like the Agattu, but the throttle control of a hub bike . I am using a 24v 16ah Ping battery with it, and ran it flat last week for 16.3 miles up mostly hills in 1 degree C weather with pretty much minimal pedalling and averaged 19 mph. My journey to work is 19 miles. I did the trip anyway on Tuesday when the weather was -4 degrees C going into work. I pedalled quite a bit (mainly just to keep warm!) and the battery lasted easy into work at an average of 15.5 mph, so now I am not so sure I need the additional battery. Being able to use the low gears and pedal at a fast cadence up hills with the Cyclon assisting is a blast - I can tackle most normal hills at about 12 to 15mph quite easily. 10% hills are about 10 or 11mph. Anyway, thanks for your advice - I'll post back if I decide to get the extra battery in case anyone wants to try something similar.

 

[flecc]

Thanks Citrus. The Cyclone system is very appealing, effectively an update on our early TGA-Electrobike and also many others in the intervening period, and it's a pity that they mostly don't succeed in the market.

Cyclone have lasted quite well, but the restricted space for the unit and number of bikes it can be fitted to is very limiting, and I think that puts many off trying it. Lots of bad publicity in the USA concerning waterproofing and corrosion hasn't helped, nor did a bad period when they were supplying kits without connectors, wrong colour codes and an inaccurate wiring diagram.

Still, you're getting a good performance from yours, and having a throttle on a drive through the gears bike has lots of motorbike like advantages.

I hope Li Ping is able to say that coupling the two BMS is ok, since that would definitely be the most efficient and easiest way.

P.S. What Wattage cyclone kit did you buy?
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[Citrus]

Hi flecc,

Thanks for the reply. I bought a 500 watt motor, which I know is not legal in this country unfortunately. However, I genuinely haven't bought it to be a speed junkie, just to get decent help in headwinds and steep hills - which it of course it does really well. I haven't had a problem with rust apart from some surface rust on the bottom bracket spindle (now covered in grease). The front 44 tooth sprocket is rust free as is the drive sprocket. The motor has been sealed with aquatic silicon adhesive - used to seal fishtanks and immediately waterproof after 10 minutes. All the connectors have been wrapped in self amalgamating tape - so I think I have done all I can. As an aside, I am on my second motor as I managed to get water ingress into the first Cyclone motor as I hadn't waterproofed it. The spray off the roads at this time of year is a nasty mixture of water, dirt and rock salt which I think corroded the circuit board for the controller which is housed in the motor. The replacement motor I have has been thoroughly waterproofed now and seems very good.

 

[flecc]

That 500 Watt is a sensible choice, and I think our law has to be ignored where Cyclone motors are concerned. All reports are that the 180 Watt one is pathetically weak and it seems the 360 Watt is an absolute minimum. Since that breaches the law anyway, going to the 500 Watt makes sense, though it is a bit greedier of course.

We've got at least two other Cyclone owning members, SteveW most recently fitting one to a trike for some load carrying.
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[Citrus]

I was concerned about the Cyclones reliability after I had bought it and then subsequently read your concerns about it and the fact that Russ had one and it didn't go to well. However, so far it seems to have worked out okay, albeit after some modifications. Once it has done 2000 trouble free miles like my Agattu did, then I will be more convinced.

 

[flecc]

I'm fairly sure that the bike Russ had was the 180 Watt version which never had enough power, so that would account for dissatisfaction, the bike itself also being quite heavy.
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[Citrus]

Li Ping's reply

"You can connect them in parallel but please add diodes to avoid current
between the packs. It's important. Or, one pack will be charged without the
BMS's protection by the other pack. That will destroy the first pack.

Best regards,

Ping "


So there you go. Exactly as flecc said (and my dad). I will get some schottky diodes and order a second battery now that I know it will work. Will let the forum know how it works out when I have done it and include a few photos.

 

[flecc]

Thanks Citrus, it's good to have that confirmation.
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