Ping 48v 20ah parallel setup questions

[DT98]

I have two Ping 48v 20ah batteries I want to connect in parallel on my bike with a front Crystalyte Phoenix brute motor. I am way too short for my weight on the chart so I need lots of powr to ride the 20 mile RT to work each day.

Ping said I should use two diodes on the setup and he provided them at a good price. So I wired the batteries and diodes as shown in the diagram on Ping's website. As I understand, using the diodes keeps the two batteries from trying to constantally balance themselves.

I went for a short ride about 5 miles and then put the batteries on the chargers. Here is where my questions start...one battery had all the LEDs (except one) come on rather quickly. The other battery took much longer so I'm wondering...it seems to me that one battery might have done all the work but I think the current draw should have come from both batteries equally. Am I wrong in this assumption?

Both diode cases did get very warm so curiosity got the best of me and I opened one of the diode cases up. There were two three leg components in the box which looked more like some type of transistor to me. The middle leg of each component were common together and the outside legs of each component were commoned together. It didn't look like any diode I have ever seen before.

Next, when the charging was complete both batteries measured exactly the same voltage. I measured at the charger plug after i disconnect the charger. This morning each battery was 60 volts on the dot. That seemed very strange to me. I left the bike at home and drove the car to work. When I got home I measured the voltage on each battery at the charger plug and both of them still measured the equally exactly, 57.4 volts...

I'm going to ride the bike again on Thursday and see if it appears one battery is doing all the work by watching to see if the same battery balances much faster than the other battery.

On the 5 mile ride last night the CA showed the Vmin at 49.2 and the Amax at 60. It is somewhat hilly around here and when I gave it full throttle I would generally see amps in the 20 amp range...sometimes 24 to 28 amps. The motor housing was warm to the touch after the 5 mile ride.

This is a new setup for me and I really want to exercise both batteries equally. I'm abut 330lbs and it's going to be a hard life for the bike and motor system. I want to do this right...

I am thinking about emailing Ping to ask but i hate to bother him about such a small setup question. I am really curious about the diode things...

Thanks

 

[chvidgov.bc.ca]

It seems strange to me that the two batteries have the same terminal charged voltage if you are using two chargers if they are of different voltages, which implies that one battery is charging the other in spite of the diode setup, which I assume is still connected while you are charging?

 

[dogman dan]

One battery may have a slightly slower charger than the other, or one battery may be slightly less balanced. So one 5 amp charger may be putting out an actual 4.8 amps and the other 4.5, or whatever.

You could put the CA on one battery, then the other, and see if the same ride produces similar numbers. One battery could be putting out slightly more watts, because of some reason in the wiring. Better contact on a connector, or whatever.

 

[DT98]

Here is more info I should have included...

I am using two chargers but they are the 2A chargers that come with the batteries.
There is a key switch wired before the controller. I make sure it is off before connecting the chargers.
Off each battery connection on the + wire, there is first a fuse holder, next is the diode thing then the + wire parallels to the other battery + wire.
I had the key switch off during the last charge and for the next time I charge, I am going to pull both fuses so each battery should be totally isolated.

Is there some other way I can verify the current draw from each battery wnen riding other than connecting two CA units?...now there's an idea if that would work!

 

[dogman dan]

Only way to get hard data, would be to have a wattmeter on each battery. I think you could do a "standard ride" and then measure the watts on one battery, then repeat the ride with the wattmeter on the other battery. Then compare them.

It might also be worth trying, to see if one battery finishes charging first one day, then the next day swap the chargers. Mabye you just have one charger faster than the other. You can seperate the batteries when charging like you said, and see if it seems any different.

If you really had one battery charging the other, then putting a charger on one battery would show a voltage increase on the other. That should be pretty easy to test, by just putting one battery on the charger after next ride, and seeing what happens.

Reading back to your first post, I'm not clear how fast the one battery charged compared to the other, or how long you expected it to take. You could just have a poor connection on one of the batteries, and indeed, be running the bike on just one battery. Dual wattmeters might be a good thing for you to have for the long haul. Maybe get a pair of cheaper ones, like from hobby king. You'd want to know pretty soon, if you started running that motor on just one of your pings.

 

[el_walto]

I'm using the ebikes.ca battery joiner diode that they don't make anymore. I really have no idea if it's configured correctly or what the schematic looks like inside, as I've never had a pack run down to the cutoff voltage with this configuration.

 

[dnmun]

you don't need the diodes. go ahead and remove them. if the packs are matched in voltage and are of the same chemistry then you do not need to use diodes to separate them. it just eats up power and will cause a fire if you have it buried in your pack.

you can charge them both at the same time with the same charger. if one pack reaches HVC cuttoff then that BMS will stop the charge to that pack and the other pack will receive all the current. otherwise no big deal.

 

[wineboyrider]

Or put them in series and dial down your amps and use only one diode??
8)
Assuming of course that your controller can take the voltage?

I do remember Ping telling me to use diodes for paralleling packs too if I remember correctly.?

 

[dnmun]

ping may have told you that but you do not need a diode to parallel them if they are the same chemistry and voltage. i told you that.

do not use diodes unless it is different chemistries, and in that case just don't mix them to begin with.

 

[wineboyrider]

ping may have told you that but you do not need a diode to parallel them if they are the same chemistry and voltage. i told you that.

do not use diodes unless it is different chemistries, and in that case just don't mix them to begin with.

You told me what?

 

[DT98]

Ok so today after work I went for a ride...say about 5 miles and there are some slow uphill grades.
I went a short piece with both batteries connected and the voltage dropped from 53.9 to 50 or 49 pretty quick but the CA showed pulling high 30s to mid 40s in amperage.

Next I disconnected one of the batteries and I could really tell a difference. The amperage still was in the 30s and 40s but the voltage dropped lower to around 48v.

Then I reconnected that battery and disconnected the other battery. Same range of current draw and the voltage dropped around 48'ish.

Then I reconnected both batteries and the voltage dropped to around 50 and 49 volts with the current draw in the 30s and mid 40s.

So I can truly see a difference with the parallel setup. Tonight the 2A chargers are working hard and the cases are very warm. These are the black plastic housing chargers.

I agree that the only way to truly measure the draw on both batteries is to put another meter on it. I ordered another large screen CA unit. I am going to hook one to each battery and get the readings. Afterwards, I will move one of them to the trike I have which has the same Clyte Brute motor and two 48v 20ah Ping batteries so I can justify buying it... at least in my mind

I agree about the diode things...they do get WARM so I will probably do away with them or at least move them where they can get more air flow.

The large screen CA units are at least a week away because of a parts supplier problem...

I'm checking the batteries to see which one charges fastest. Also, I have at least one LED on teh BMS that never lights. I hope it will balance after a few cycles.

 

[dnmun]

i repeat for the 3rd time. you do not need to put a diode in the connection between the two packs. these are identical batteries and they do not need a diode for protection.

 

[wineboyrider]

i repeat for the 3rd time. you do not need to put a diode in the connection between the two packs. these are identical batteries and they do not need a diode for protection.

I agree the bms 's should be fine, because they are nearly identical. 8) 8) 8) 8)

 

[BikeFanatic]

I have that EBIKES.CA diode and it does get hot and wastes amps ( I think 2 amps measured on 36 volt battery) So If the GURUs tell you it is not needed do not use it. It maybe too late, but FYI a "watts up" or turnigy meter from hobby king are alot cheaper than a second cycleanalyst.

I use the diodes when mixing batteries of different chemistries, My old NIMH and a new lipo.

 

[DT98]

I have heard and listened I am going to remove the diodes and see how it runs without them. Identical batteries/bms it should be ok...but I still wonder why Ping recommends using the diodes... I might email and see what he reports.

 

[wineboyrider]

I have heard and listened I am going to remove the diodes and see how it runs without them. Identical batteries/bms it should be ok...but I still wonder why Ping recommends using the diodes... I might email and see what he reports.

The only time it would be of concern would be if one battery is in a different state of charge and/or discharge, but I assume you would be charging and discharging both batteries in paralell?
8)

 

[el_walto]

Without the diodes, what will happen if one pack reaches LVC before the other one? I think if they are in series they will fry a BMS? In parallel they would be fine?

 

[neptronix]

Without the diodes, what will happen if one pack reaches LVC before the other one? I think if they are in series they will fry a BMS? In parallel they would be fine?

One won't hit LVC before the other.
If you parallel batteries.. they will become effectively one large battery, and if one tries to go low, the other will charge it; they will constantly be equalized.

If you are going to connect them in parallel, you need to make sure the voltages are within about 0.05v first, however.
Because when you connect two batteries together and they try to charge each other very rapidly.. it could go kaboom or be damaged due to one battery receiving way too much current at once.

I am not aware with how charging works when you have two batteries with BMSes paralleled together though.

 

[dnmun]

@ el walto, if they are in series then the current flow will immediately cease.

if they are in parallel then the pack that has the BMS shut from LVC will not flow current and all the current to the motor will come from the one pack left working.

ian had it exactly right. when you combine two different chemistries in parallel then you use a schottky diode to prevent current flowing from one pack into the other since they will have different resting voltages when the load is removed. so in that case the current would not flow out of one pack into the other because the schottky diode can withstand the difference in voltage.

also if you analyze it, there is no need to use a schottky with a high reverse breakdown, of a value equivalent to the maximum total pack voltage. since the voltage difference would just be the difference between the two packs when they are resting, it could be only on the order of 4-5V i would expect. so instead of having a 60V diode, you could use a 8V diode and get much more amperage capacity and for much less money. plus i expect the forward bias may be just a little less.

the power loss through the diode is IV, if the current is 120A and the forward bias is .4V then the total power loss or heat generated is 48W, as much as a big fat halogen headlight, or two, or three, or ten led headlights.

 

[el_walto]

Ok so today after work I went for a ride...say about 5 miles and there are some slow uphill grades.
I went a short piece with both batteries connected and the voltage dropped from 53.9 to 50 or 49 pretty quick but the CA showed pulling high 30s to mid 40s in amperage.

It sounds like you don't have fuses on your battery packs? I'd highly suggest it. I once accidentally shorted two packs together when in a hurry and changing configurations around. Well the 25Amp blade fuse was completely vaporized into smoke. It pretty much destroyed/melted the fuse holder at the same time. This all happened in less than a second before the BMS kicked in i guess. A 30-40 amp fuse on each battery would ensure that you are not pulling too much current from them.

I'm just happy I didn't have to call the fire department.

I run two pings with a 40amp controller and a 25amp fuse on each battery and don't seem to have any problems.

 

[DT98]

I emailed Mr. Ping to ask about the diodes and he emailed a reply this morning. (Ping gives fast service! A+)
His reply is below word for word.


"Yes, the diodes consume power. If current is high, they will also consume high.
You can get rid of the diodes, but please make sure all the packs in parallel are at the same charge level. If you connect one fully charged pack in parallel with a 50% charged pack, there will be big current between them. That big current could be harmful to both packs. The diodes are just to prevent such things happen, even if the type or chemistry of the battery packs are totally same.
The components are exactly diodes. There’re two diodes in parallel on the circuit board with metal heat sink plate."

 

[999zip999]

That brute motor will make great demands on those pings if let loose. I would keep this in mind when doing your up hill test. If you are trying to see if they will sag. Total watts used. And why don't all your leds light up ?