Re: How do I connect 2 LiFePo4 48V 20ah batteries

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snowryder
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Hello Everyone, been reading all the great threads! So, Here is my first attack plan :

1) I just purchased a new x-treme scooter XB-700Li with the newly upgraded 48V 20ah LiFePo4 26? cell battery pack (instead of the original 26 cell LiMnO4 Ion battery pack) and I want to add the new Cammy_CC 48V 20ah LiFePo4 pack(has a high tolerance BMS) that I purchased, under the scooter seat as a secondary battery pack to increase the range. I want to hook them together in parallel to create a 48V 40ah pack that can be charged from the charging port on the scooter(I know it will take twice as long to charge). I do not think the XB-700Li has a BMS(the original models did not) and I could recharge the seconary Cammy_CC pack alone to balance the cells once a week or so. What is the best way to hook my new 48V 20ah pack to the stock pack? I think I need to drill two small holes in the seat box and put the negative lead from the secondary battery pack to the last negative terminal (farthest from the negative discharge wire terminal) on the primary pack and put the positive lead from the secondary pack to the last positive terminal(farthest from the positive discharge wire terminal) on the primary pack? I don't want to make to many changes or reconnects to do this mod but, am I correct or am I missing something ??? THANK YOU !!! - I know this is confusing - I can't get my camera to down load any pictures - I will try to down load some photos in the next few days, I HOPE !!!!

P.S. Words to live by : "In the immortal words of Socrates - " I drank what?" "

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robert93
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Re: How do I connect 2 LiFePo4 48V 20ah batteries

With 2 non-identical packs, with same voltage, i would recommend battery isolation, where one battery does not try to charge the other, but both are available to current draw. On charging, you might do better by charging them as two separate batteries, not only for time, but also to make sure the charger is not overworked. There are others far more qualified to address this than me, so I'll sit back and learn....

snowryder
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Re: How do I connect 2 LiFePo4 48V 20ah batteries

THANKS, I do or will have two different battery chargers!! How do I wire in isolation? Do I connect to main power wires after the scooter charging port but, before the controller?

reikiman
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Re: How do I connect 2 LiFePo4 48V 20ah batteries

I'm wondering about the isolation as well... FWIW I'd asked pingping a similar question a long time ago and he recommended against connecting two of his batteries in parallel.

Anyway, isolation ..

a) diode? Keeps current from flowing upstream, the diode has to be big enough for the current. The downside is the diode results in a voltage drop.

b) Switch to connect one pack and then the other. It's not as convenient as connecting in parallel. It would keep them from feeding each other.

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snowryder
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Re: How do I connect 2 LiFePo4 48V 20ah batteries

THANKS AGAIN, Great info - I should have posted this thread last month, then I could have it all figured out in advance instead of buying parts I didn't need!! I purchased a Cutler-Hammer C362NR40 600V - 40amp general purpose switch , it has 3 terminals on one side and 3 terminals on the other side but, I don't know which terminals are for the input power and which are for output? One side has the markings L1, L2 & L3 near the top next to the terminal screws and lower near the bottom of the terminal screws(where the screw tightens down on the power wire) is markings 1, 3 & 5 and the other side has ( no ) top markings but, has 2, 4 & 6 marked down by the bottom of the screw terminals (where the screw tightens down on the power wires) !!!!!!!!! I may have to go to an electrician to have it confirmed. THANKS AGAIN !!!

reikiman
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Re: How do I connect 2 LiFePo4 48V 20ah batteries

The kind of switch to use is - DPDT - double pole double throw ...

What that means is one switch controlling two side-by-side connections. You have pack A, pack B, and a DPDT switch lets you select between the two of them.

DPDT switches will have six connections. You can think of a DPDT switch as having two inputs and one output (or maybe one input and two outputs).

A multimeter is useful for exploring the possibilities of the DPDT switch...

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- David Herron, Green Transportation Examiner, Green Transportation Info, The Long Tail Pipe, Electric Race News, davidherron.com, 7gen.com, What is Reiki
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strawhistle
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Re: How do I connect 2 LiFePo4 48V 20ah batteries

He may also have a 3 pole single throw switch. L generally means line side or battery! That may be a 3phase switch. LaTeR

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snowryder
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Re: How do I connect 2 LiFePo4 48V 20ah batteries

Thanks to Robert93,Reikiman & Strawhistle, It seems to be a disconnect switch. when I use the multimeter the first terminals on each side connect when the switch is turned one way and when I turn the switch the other way - they are disconnected. All Power comes in on one side and outputs on the other or it's OFF. I will be looking for a high output DPDT switch, I guess!!!!!

strawhistle
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Re: How do I connect 2 LiFePo4 48V 20ah batteries

Please make sure the switch is for low voltage DC or the contacts in the switch will burn and weld together. it may be easier to find a dpdt ether or solenoid. LaTeR

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snowryder
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Re: How do I connect 2 LiFePo4 48V 20ah batteries

THANKS Strawhistle, I know most switches list ac Voltage and current but, what is considered low voltage DC? Under 100V?, 60V?, etc. I have a 60amp rain proof reversing drum switch that I am looking at on ebay. I am waiting for the manufacturer to e-mail back if I can use it the way I want to. Wish me luck !!!

strawhistle
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Re: How do I connect 2 LiFePo4 48V 20ah batteries

Have you thought about Anderson connector for the cammy battery and for the wires from the bikes battery + to + and - to - then disconnect to charge batts separately then connect to run ??? that should work also. LaTeR

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snowryder
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Re: How do I connect 2 LiFePo4 48V 20ah batteries

strawhistle wrote:

Have you thought about Anderson connector for the cammy battery and for the wires from the bikes battery + to + and - to - then disconnect to charge batts separately then connect to run ??? that should work also. LaTeR

Thanks Strawhistle, As I wrote in my first post - I wanted to connect the positive discharge wire from the Cammy battery to the first positive terminal(farthest from the pos. discharge wire) on the scooter battery and do the same with the negative Cammy discharge wire to first negative terminal(farthest from the negative discharge wire) on the scooter battery pack. Do I have this correct? I would want to put a pair of terminal wires from the scooter battery back to the seat well and put in the anderson connectors there so, I can disconnect it there!! The change would be to put in the anderson connectors. Are 50 amp andersons enough? Or how high do I have to go? The x-treme website states that the amp rating is 40.0 but, The Cammy battery pack claims to have a rated discharging amperage < or = to 20amps; a max discharging amperage of 40 amps; a max discharging current of 60 amps; a discharge cut-off protection of 40 amps - So, i was hoping 60 amps would be enough!!!!!! Thanks

strawhistle
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Re: How do I connect 2 LiFePo4 48V 20ah batteries

Hi Snow , as your new battery from cammy has only a 1C rate and it is a 20 ah battery you can get two pair 30A Anderson power pole connectors and that should do it ! let me know how it works out. LaTeR PS. generalwerks sells a 10 pack red and black for $9.?? plus shipping

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snowryder
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Re: How do I connect 2 LiFePo4 48V 20ah batteries

strawhistle wrote:

Hi Snow , as your new battery from cammy has only a 1C rate and it is a 20 ah battery you can get two pair 30A Anderson power pole connectors and that should do it ! let me know how it works out. LaTeR PS. generalwerks sells a 10 pack red and black for $9.?? plus shipping

Thanks Straw, How can I connect (2) 48V 20ah packs into one 48V 40ah pack, safely, with the anderson connectors?I looked at the new XB-700Li LiFePo4 pack and I don't want to hook into wires in the pack - I want to plug into the IEC C14 male plugs on the battery boxes and still combine them into one 48V 40ah pack then run this pack as the secondary pack from a Blue Sea Systems PN3003 w/a alternator field disconnect 4 way battery switch(off, batt #1, Batt #2 & Batt 1&2) then to the motor power cord. Can I connect the (2) 48V packs into one 48V 40ah pack by using a 15a 14AWG SJT Dual/ Y- splitter cord with (2) IEC C13 female plugs on one end, to plug into the IEC C14 male plugs on the batt packs (and a NEMA male plug on the single end of the Y- splitter) and then connect a same gauge NEMA female plug cord end with a IEC C14 male plug on the other end to the female IEC power plug to the hubmotor(700W)? Will this be in parallel or am I missing something? THANKS AGAIN!!!!!!

Thanks, Could anyone send me good photo's or diagrams of how you build a DIY 48V 60ah LiFePo4 battery pack and 60V 40ah LiFePo4 battery pack? I have (2) 48V 20ah LiFePo4 packs that I am adding to a new X-treme XB-700Li scooter(w/ new LiFePo4 upgraded - only 15ah to 17ah) to extend the range and I purchased 600+ 18650 cells(will have to buy more) to build a custom(DIY) 48V 60ah batt pack to carry in a pull-behind trailer. And I may also put a small generator on the cargo trailer to recharge the low batts and maybe add a little current to the working battery or motor to extend milage for long road camping trips(series-hybrid trailer). Then, next year I will try to buy 60V or 72V electric motorcycle and I will want to convert the (2) 48V packs to 60V or 72V and rearrange the custom DIY pack to the same voltage for long trips. I have a higher tolerance 48V BMS(I think it was set for 20ah pack and possibly may not be able to be used on a 40ah or 60ah pack) that I purchased from Cammy_CC to use on the 48V DIY batt pack but, I will have to purchase a 60V or 72V BMS and Charger. Please, Help !!!! snowryder

snowryder
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Re: How do I connect 2 LiFePo4 48V 20ah batteries

SORRY Straw & ALL, Let me simplify this:
1) XB-700Li(has 48V 15-17ah? LiFePo4 batt) has a male C14 IEC plug/terminal on the batt box. I plan on plugging a Heavy duty 14awg SJT female C13 plug into the batt boxes' male IEC C14 plug and run the cable to a Blue Sea systems(hard wired under the seat) 48V 500a - 700a marine battery switch (4 positions - OFF,Batt #1, Batt #2 & batt's #1 & 2)(#PN3003)with an alternator field disconnect( in case I add the series-hybrid generator/ battery trailer later) as Battery #1.
2) I need to combine my two(2) 48V 20ah LiFePo4 packs into one. One battery will be under the seat, the 2nd batt will be in a tackle box on the floor boards by my feet and the power cable(to the hubmotor) w/ a female IEC C13 plug will be easily rerouted to the seat box. Can I parallel the two(2) packs by twisting the two(one from each pack)red positive discharging wires together and inserting both into one terminal of the first 175a anderson connector and twisting both black negative discharging wires together and inserting them both into the other terminal on the first anderson connector and run a single red(pos) wire from the 2nd anderson connector's positve terminal to the battery switch and repeating the same for the one single black(neg) wire from the 2nd anderson negative terminal to the battery switch? Does this parallel the two packs safely? So that batt #1(48v 15ah?) is from the scooter to the 48V battery switch and batt #2 is the combined two (2) 48V 20ah packs into one (1) 48V 40ah pack to the battery switch? Thanks again!! PEACE OUT !!!!!

snowryder
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Re: How do I connect 2 LiFePo4 48V 20ah batteries

Dave Herron, Strawhistle and All ---- I tried to copy the diagram but, I can't get to work - I will try again to copy and download the diagram. I want to know if I hook the positives from each battery to the switch and the power output positive to the motor/controller then I should be running the negative from the the motor/controller back to the batteries and I need to know if I should put the schottky diodes on the negative discharge leads from the two packs(one negative wire into the two negative battery leads tied together- Y'ed) or if it is a waste because, I will be switching from one pack to the other with the battery switch??? So, power should not be able to reverse to the off battery and if I combine them with the bank 1 & 2 position then the power will return to both battery packs because the curcuit is open to both? Is that correct?? Can I connect the two Battery pack negatives into one and connect that one to negative wire comming from the hubmotor/controller??? Thanks - snowryder

strawhistle
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Re: How do I connect 2 LiFePo4 48V 20ah batteries

OK snowryder, I don't know the switch you have! lets draw. . 2 battery's 1 is the scooters original and no. 2 is the added one! From the + - posts of the 1 bat add new connectors and wire to go close to no2 battery. . Put your "switch" or Anderson connectors on those 2 wires, . put connectors "or switch" on the 2 power wires from battery no.2 . plug in battery no 2 to run and disconnect to charge.
lifepo4 battery's need to be balanced and your new battery comes with the BMS and wires to each cell! DO NOT try to charge both battery's with one charger! they must be totally disconnected both the + and - or else you may short out between chargers DISCONNECT TO CHARGE ! RUN CONNECTED catch you LaTeR

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snowryder
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Re: How do I connect 2 LiFePo4 48V 20ah batteries

Thanks Strawhistle, The battery switch is #6007 on www.bluesea.com website and is only for connection of the positive wires from different batteries with no negatives hooked to the switch. I think I need to connect the positive discharge wire from battery #1 to the Battery switches' bank #1 terminal and the positive discharge wire from battery #2 to the battery switches' bank #2 treminal and then connect the common terminal(positive) from the battery switch to the positive wire going to the controller/hubmotor. Then I will have to connect the battery #1 negative wire to the negative wire of battery #2(y-connect by twisting the two wires together in an anderson powerpole connector) then run that negative wire to the negative wire going to the controller/hubmotor to complete the curcuits. I hope I can recharge each battery separately(with two chargers) when I turn the switch to the off position, stopping the curcuits to each battery pack. If I turn the switch to bank #1 I was hoping to be able to charge the off battery while the battery #2 was running with a small generator pulled behind in a cargo trailer for long trips. But, do I/should I install anti-reversing diodes on the negative wires from each battery pack(#1 & #2)? I am hoping to not disconnect each pack for recharging, just turn the switch to the other bank or off !!! Thanks for all your help and I this doesn't inconvenience you, much!!! Mark

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