Both batteries needed?


Well-Known Member
Hey Guys
Ok, I finally discharged the batteries down to 30% per info on the controller.

I pulled the bottom battery out and started recharging it back up,
only have 1 charger at this time on this is on a Wart Hog MD 750 bike.

I went to check the mileage on the controller,
and I could NOT get the bike to power up, with only the top battery in it?

Is this normal, that both batteries have to be in place for the bike to work?
What good is 2 batteries if only the bottom one operates the bike?
The top one is just along for the ride?

Your thoughts and suggestions...........

Most bikes work like that, with a 'primary' and secondary battery - including Specialized, Trek, etc.
Shorter rides, lighter bike - install the primary. Longer riders - install both.
Having a specific position for the 'primary' isn't really a big deal, and the lower one is preferable as being primary due to weight distribution.
If you only put in the bottom battery, the bike turns on and works, and after discharging both batteries, they both show drain/similar levels, right?
Thanks for the info,

Seeing that I am a new owner of this Ebike, and really don't know much about it, slowly learning,
reason for the dumb questions being asked........LOL

"If you only put in the bottom battery, the bike turns on and works, and after discharging both batteries, they both show drain/similar levels, right?"

I don't know what the drain levels were on each battery, the display showed 30% of power left,
so I recharged the both of them, took several hours for each to charge up.
I'll check on the next recharge of the batteries and make a note etc.

I don't know for sure which of the 4 slots on the connector plug is + or -,
so I can check with a volt meter etc.
I am looking at the battery right now, and I don't see any plus or minus symbol's on or around,
any of the battery connection slots etc.

The only information showing on the bike, at the battery connection plug is # 1 and #2,
there is no other information that I can see.

Is there a battery schematic,
that shows the + and - terminal's for this 48V - 15AH-720Wh battery somewhere?

If both batteries took time on the charger, the 'dual battery electronics' are basically doing their job properly.
The display is kind of an aggregate. There are different strategies some dual battery systems use, e.g. primary first and THEN secondary, or roughly both concurrently...the display should show a combined percentage, and at least from what you said on both batteries charging individually took some time - seems all is well.
Here is some interesting info I just found out about the top battery, that I had questions on.

Finished a ride today,
started with 68% per display, traveled 37.5 miles,
returned home and the battery percentage read 30%, per display.

Brought the bike inside as it was getting cold outside,
pulled the bottom battery and had a reading of 46.6V via a voltmeter,
pulled the top battery and had a reading 331.3V ?? tested several times via voltmeter.

Put the top battery in the bottom slot and got a "O" - NO reading, from the display,
and the little push lite did not show any color, pulled the top battery,
and put in the bottom battery, and got a reading on the display of 31.8Volts,
and the push lite lights up to the Blue color.

So it appears that I have a battery problem, with just about 75 total miles.

Question for you,
Would there be any problems with charging the top battery,
I am Leary of this type of battery etc.

I'll charge the bottom battery up and take a reading when the charging lite changes color.
I'll contact Bikonit, Ist thing Monday morning, I hope they replace it.

Your thoughts and suggestions..
I just found out that these battery's are the LG Chem 21700 Cells,
if that makes a difference,

I got contacted by the Bikonit service section, and they wanted a bunch of information which I provided etc.
I wonder if they are going to send a new battery to replace this bad one under warranty,
as they asked for my full address?
I wonder if they have someone at Bikonit that reads these forums?

Per Bikonit, "Do not use or charge the #2 (Top/bad battery.

Charged up the #1 (bottom) good battery and got a full battery reading of 53.7V, after setting for an hour,
charge time was approximately 3hrs 15 minutes.

I hope it is OK to do some lite riding, as We have some bad weather coming next week,
using just the bottom battery?
I'll stuff some plastic into the top slot and secure with tape or bungy cords.

I just got a bunch of the items I ordered for the new bike an got it all installed,
along with the new Garmin GPS/antenna mount etc.

I just got in and have a battery reading of 50.3V for 6.2 miles travel, (used 3.4v),
when I left the battery was 53.7v, the display said I had 76% remaining.
I also found out that the speeds limits are off in the display by 2.3 mph, (faster)
than the Gps speed readings. I know the GPS is accurate............

Had a good quick ride to test everything, have to add a strong back to the GPS shelf, vibrates too much,
Along with a ground loop into/on a frozen puddle, nothing hurt or damaged except my pride,
and wet pants from the puddle and that's not the first time...............LOL
Thanks RTP
I finished a short ride and saw that the battery used more than usual of battery for the 6+ mi ride.
Was just testing some of the items I added, have to work on the GPS shelf, not happy with it.
I am shocked,
just received a notice from Bikonit, to send my bad battery back to have a new one sent to me,
they are sending me some type of special shipping container for the battery?.
I am tickled Pink with that information.