Li Ion Battery 36V 16Ah

[kostelacj]

I measured the voltage of this battery on arrival at about 36v. I used the provided charger and when it indicated charging was complete I checked the voltage again, 41.5v. Hmm. I ran the newly configured bike and have recharged the pack several times. It is quite consistent. And since I see folks running the 36v controller with 41, and even 48v. I was not worried. I am interesting in finding if anyone else is experiencing this?  Also, I measure the voltage before and after rides to correlate the top speed at the start and end of the ride with the voltages at the start and end. They follow nicely. Today, 15 miles of nothing by battery, max speed (20 inch rim) of 18.8 at the start and 16.4 at the end. Voltage went from 41.5 to 39.6 which is within a half percent of each other.

Anyway, I am curious about what others are seeing in performance and what the cutoff voltage is on this battery as well as any experience running the 36v 750W motor and controller at even higher voltages.

Thanks,

John

[Barry]

Your voltage readings are normal. You should be worried if it only read 36 volts after charging.

A typical 48 volt battery will charge to 52 volts or more, depending on the specific chemistry.

You Golden Motor 36v  16Ah battery is probably Lithium Manganese (LiMn) even though their website implies that it is Lithium Iron Phophate (LiFePO4). Email them and ask if you are uncertain.

The low voltage cutoff, when the motor quits working is at 32 volts. You do not want it to charge higher than 42 volts and it should not if all is working correctly.

But if you are riding and the motor starts cutting out due to low battery voltage, and then you stop and measure the voltage, it will likely read considerably higher than 32 volts. The voltage would be only 32 volts when power is being drawn from it. It will rise up considerably by the time you stop the bike and attach a voltmeter, maybe even to 36 v or so.

[kostelacj]

Just for fun, I have a digital volt meter hooked up so that I can monitor my "gas gauge" while riding. It hasn't gotten below 36 while riding after 15 miles.

Now, based on the announcement from Yao Yuan about voltages, I am wondering how to "up" the voltage I carry with the Li batts to closer to 60v without have to by more Li batteries just now, eg adding a 12v SLA? Ideas anyone?

[Perbear]

Now, based on the announcement from Yao Yuan about voltages, I am wondering how to "up" the voltage I carry with the Li batts to closer to 60v without have to by more Li batteries just now, eg adding a 12v SLA? Ideas anyone?

You would not gain much from using SLA in series unless it is a very expensive SLA. Since the internal resistance in cheap SLA is quite high you would be much better off buing a LiPo pack for RC models.

[pieroh]

Now, based on the announcement from Yao Yuan about voltages, I am wondering how to "up" the voltage I carry with the Li batts to closer to 60v without have to by more Li batteries just now, eg adding a 12v SLA? Ideas anyone?

You would not gain much from using SLA in series unless it is a very expensive SLA. Since the internal resistance in cheap SLA is quite high you would be much better off buing a LiPo pack for RC models.

I am using 36V-2Ah Bosch Li Ion Battery Packs . Two of these in parallel take me the way to work and back (27km), with pedalling of course.
Some US sellers at ebay are offering them for ~ 50$US each.

[Barry]

I am using 36V-2Ah Bosch Li Ion Battery Packs . Two of these in parallel take me the way to work and back (27km), with pedalling of course.
Some US sellers at ebay are offering them for ~ 50$US each.

But the OP is wanting to add 12 volts, not 36.

[Bikemad]

Now, based on the announcement from Yao Yuan about voltages, I am wondering how to "up" the voltage I carry with the Li batts to closer to 60v without have to by more Li batteries just now, eg adding a 12v SLA? Ideas anyone?

Click for full size image

This should do what you're asking, but I would only use it as a temporary boost rather than continuous operation, because if the extra battery is of a lower Ah rating than your existing pack it will become excessively discharged before your main pack runs low enough to cut out.
It would be ideal for an extra boost on steeper hills and for overtaking etc.

It would also need a separate charger.


Alan

[Barry]

But what do you suggest for the extra 12v battery?

[Bikemad]

But what do you suggest for the extra 12v battery?

I would be tempted to use a 12V 18Ah Deep Cycle Sealed Lead Acid battery, as fitted to various types of mobility scooters and powered wheelchairs etc.

These batteries can be used in any position and usually recover well from a deep discharge.
Nominal Capacity
20-hr. (900mA to 10.50 volts) 18.0 AH
10-hr. (1.7A to 10.50 volts) 17.0 AH
5-hr. (3.2A to 10.20 volts) 16.0 AH
1-hr. (11.1A to 9.00 volts) 11.1 AH
15-min. (34.3A to 9.00 volts) 8.58 AH
Internal Resistance (approx.) 14 milliohms
Max Discharge Current (7 Min.)  54.0 amperes
Max Short-Duration Discharge Current (10 Sec.) 180.0 amperes
(Length = 181mm, Width = 76mm, Height = 167mm and Weight = 12.6lbs/5.72kg)

I bought one of these jump starter/tyre inflators recently from a local discount store for £23 (approx 35usd).
Cheaper than buying the 12v 20Ah battery on its own and it came with an air compressor, tripple LED light, a slow 500mA charger, voltmeter, switches, charging socket and leads etc.

Now that's what I call good value!

If it can supply enough Amps to start a car, I'm sure it would work fine as an extra boost battery.

Alan

[kostelacj]

Alan,

Thanks. I am going to try this based on that beatiful schematic. it would be fun to have that EXTRA BOOST of speed.

John

[Gregte]

I recently added a "super charger" battery to my existing 36v LiMn battery. I set it up so I just press a hadle bar switch (I use the headlite switch) to insert an extra 12v NiMH battery in series. I configured the wiring such that the relay used is powered by the 12v batt since it has a 12v coil. It is also configured such that my bikes lights and voltmeter will still be operated by the 36v battery only, not the combination.

It uses a commonly found automotive relay rated at 40 amps. The markings on the relay pins are 30, 85, 86, 87 & 87a. I don't know what those numbers represent but this is a very common relay you are bound to find at any automotive parts store.

I used to get 22 mph on level ground no pedaling. Now with the extra 12v I get 26.5 mph. It is faster and more powerful for sure but I am not sure it is worth the extra 5 lbs weight and other inconveniences such as charging two batteries and losing the cargo space I had and the expense of the new battery etc.

[kostelacj]

More excellent feedback. Thank you all. I love the sharing of ideas, successes and failures. If there are any of you in the Houston, TX area who would like to get together some time, please PM me.

John

[Gregte]

love the sharing of ideas, successes and failures.

I would sure like to share more of my failures. By that I mean I would be willing to actually give them to you or anyone else who would take them!  ;-)