Voltage Across Battery Terminals...

Discussion in 'Speed Triple' started by stevie28, Jan 15, 2020.

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  1. stevie28

    stevie28 Well-Known Member

    Nov 10, 2019
    208
    93
    Cambridgeshire
    Hi all i only have a max voltage of 13.5v going across the terminals of my battery When the bike is running up to temp, and being revved to about 4k.
    This seems a little low compared to what i have read about on here...
    Does this point to reg/rec on the way out?....
    Cheers.
    Steve.
     
  2. capt

    capt Elite Member

    May 8, 2016
    2,999
    750
    western Australia
    How old is your battery ? Older bit still fit for purpose , may show only 13v~ my lithium battery only shows 13•7v and bike alternator and regulator are fine.
     
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  3. stevie28

    stevie28 Well-Known Member

    Nov 10, 2019
    208
    93
    Cambridgeshire
    I have tried it with the battery that came with the bike of unknown age lead acid, and a new lithium battery I bought the other week. Voltage same across both...
     
  4. feckless

    feckless Noble Member

    Apr 16, 2019
    957
    443
    Cumbria
    what year is the bike Steve? if a 955I of 02-04 vintage it could be the old wiring harness problem. have a look at your fuse box for signs of over heating on the charging circuit fuse., that would be a worse case scenario. I know the Daytona suffered but not sure about the SP model
     
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  5. Callumity

    Callumity Elite Member

    Feb 25, 2017
    3,355
    800
    Nr Biggar
    It would be!

    The voltage you are reading is the output from the regulator/rectifier moderated alternator. It is not too shabby...... some give a little more but a fully charged battery is 12.7v so it is getting topped up.
     
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  6. stevie28

    stevie28 Well-Known Member

    Nov 10, 2019
    208
    93
    Cambridgeshire
    It's an 08 bike, with only 15k on it.
    I'm hoping to get some garage time next week to fit new pads and discs. So I'll have to man up and learn how to do an electrical check on it!! o_O
     
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  7. feckless

    feckless Noble Member

    Apr 16, 2019
    957
    443
    Cumbria
    ignore my post then mate, I think the issue was sorted by then
     
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  8. Wishbone

    Wishbone First Class Member

    Nov 4, 2018
    848
    643
    Essex UK
    Most generators on bikes will output up to 14.5 v at max, there should be figures for voltage at a range of revs in a workshop manual. or tellus the model and someone will chime in with the values but at 4k I would expect nearer 14v but proof of pudding is does the battery start the bike ok?
     
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  9. stevie28

    stevie28 Well-Known Member

    Nov 10, 2019
    208
    93
    Cambridgeshire
    This is one of the quirky things... The lead battery starts the bike fine, the the lithium battery struggles unless the bike is warm... I took the 1st lithium battery back, thinking it was a dud, but the replacement is just the same. Very strange.
     
  10. Wishbone

    Wishbone First Class Member

    Nov 4, 2018
    848
    643
    Essex UK
    Could be the way Lithim batteries deliver current, it has lower crank amps but can deliver a higher percentage on demand and for longer.
    So lithium manufacturers have a calc they do to show their cold crank amps as higher and some overegg the figure?
    I have put a Lithium in my T120 nd it starts it fine which is good going for a big twin.
    What make of Lithium did you get? Mine was a JMT

    Did you ever charge the Lithiums?
    other peculiarity is they need woke up apparently so second stab should be stronger!!
     
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  11. Red Thunder

    Red Thunder Crème de la Crème

    Dec 2, 2014
    2,033
    1,000
    High Wycombe
    #11 Red Thunder, Jan 15, 2020
    Last edited: Jan 16, 2020
    Lithium batteries really REALLY hate the cold
    Mine can drop 0.5 volts over night if chilly.

    So in leave the lights on which activates/wakes up the battery and after trying to start a couple of times it will start up.

    One upgrade I did (thicker wires) is to the wire from battery to solenoid to starter motor, and from stator to rectifier and then direct to battery (not through ECU) and the charge is higher 14.3v, the starter is stronger, all with less stress in the stator

    Edited 16th 14:00
     
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  12. stevie28

    stevie28 Well-Known Member

    Nov 10, 2019
    208
    93
    Cambridgeshire
    Mines a shido battery. Have one on the Kwak and it starts no problem. 4 smaller pistons may help there thou... As for the temp, I think you are correct. Lithium battery seems to like it warmer. I run a Nissan leaf to commute with and that looses about 10 miles of range in the winter.
     
  13. tim8061

    tim8061 Member

    Dec 28, 2019
    49
    18
    Gloucester
    I've had two lithium batteries and neither would start the bike on
    cold days. Now I use lead/acid over winter.
     
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  14. Wire-Wheels

    Wire-Wheels Elite Member

    Apr 26, 2019
    2,166
    800
    California - USA
    Battery voltage depends on several things. One: The level of charge. Is it fully charged ? Or maybe down a bit. Two: The cutout voltage of the regulator This is part of it's built in specification. It varies a bit from one mfg. to another. Three: In a lead/acid battery what is the specific gravity of the battery acid. The higher the specific gravity, the higher voltage is possible [only to a point]. Low specific gravity [too much water] and the battery is not able to achieve a higher voltage reading, even if the charging system is capable of more, when the system shuts down, the voltage will settle at what ever point the specific gravity of the solution will allow. ...J.D.
     
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  15. sti5300

    sti5300 Well-Known Member

    Jan 22, 2020
    22
    58
    Swansea
    Have a look on the Electrix website they have a good flow chart to help you isolate what is your problem. They also do a heavy duty rectifier/regulater
     
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