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Thread: DIY Battery for Maxabeam

  1. #1

    Default DIY Battery for Maxabeam

    Ive found a maxabeam without battery so I will need to build me one. Ive built 18650 packs before (up to 12S4P) and I really like those cells. From what Ive read the maxabeam needs at least 10V to run and max 13.5V input. This makes 18650 hard to use since a 3S pack would be max and then I can only discharge to about 3.3V/cell.

    What at is my best options here? Is there any circuit I could use to drop voltage from a 4S 18650 pack down to regulated 13V efficiently or should I look into other types of cell.

    Is anyone familiar with the connectors used by maxabeam? It looks like some kind of Amphenol plug.

    I just got confirmation from Annie at peakbeam that 10-13.5VDC is the operating range but they say that powering it from the car will be fine due to voltage drop in the cables. I found a 15A stepdown from max 40V to 12V from polulu. It's rated for 32A peak current so that should work for lamp start. Efficiency with 15-20V input is around 95% so it should'nt be to bad loss. The step down can operate from 14.5V min so that rules out a 4S config. Since Peak beam has a 10Ah battery and I assume its 12V-ish thats 120Wh to use. Going with 5S3P with LG 18650 M36 3600mAh cell with approx 11.2Wh/cell at my load should give me 168Wh and counting efficiency loss of 6% around 158Wh. Since their 120Wh gives a lot of runtime I think this will be sufficient. Another benefit of using the stepdown is that the input voltage for the light will be the same from full to empty cells. Anyone see any problems here? I might look for a little bigger stepdown but 15A rated should really be fine when high beam is 8.5A. Going with panasonic NCR18650b would give the same numbers and load should be safely within the batteries spec on 3A/Battery but max 6,5A at startup is slightly above what panasonic recommends that's why I picked LG with 10A discharge.

    step down - https://www.pololu.com/product/2885
    Battery test : https://lygte-info.dk/review/batteri...yan)%20UK.html

    Maxabeam spec:

    Low Beam Mode 3.38 0.04 Amps 25C, 12VDC Input
    Normal Beam Mode 4.35 0.04 Amps 25C, 12VDC Input
    High Beam Mode 8.48 0.05 Amps 25C, 12VDC Input
    Peak Current at Lamp Start 20.5 3.2 Amps 25C, 12VDC Input
    Last edited by minim; 10-08-2018 at 10:11 AM. Reason: got info from peakbeam

  2. #2
    Flashaholic*
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    Default Re: DIY Battery for Maxabeam

    Peak Beam Systems for the Maxa Beam light supplied both lithium ion as well as LiFePO4 battery packs.
    The LiFePO4 battery placard shows a voltage of 12 volts.
    The lithium ion battery placard shows 14.8 volts.
    I just checked the voltage of both types of packs, and both indicate 13.6-13.7 volts fully charged.

    Any board that has the ability to regulate charging of a series of 18650 cells wired in a 4S configuration will be fine.
    Those that can, do. Those that can't, teach.

  3. #3

    Default Re: DIY Battery for Maxabeam

    Quote Originally Posted by NoNotAgain View Post
    Peak Beam Systems for the Maxa Beam light supplied both lithium ion as well as LiFePO4 battery packs.
    The LiFePO4 battery placard shows a voltage of 12 volts.
    The lithium ion battery placard shows 14.8 volts.
    I just checked the voltage of both types of packs, and both indicate 13.6-13.7 volts fully charged.

    Any board that has the ability to regulate charging of a series of 18650 cells wired in a 4S configuration will be fine.
    Thank you for checking. Maybe they have some sort of step down inside the pack also then. a Lithium ion showing 14.8V (nominal) should be 16,8V fully charged. Have you ever opened the battery to inspect the BMS/output circuit?

    Actually Annie specifically advised me against running a 4S Lipo/Liion battery directly as the voltage is to high. Another member I spoke with also had a servo on his going bad when trying a 4S pack so I'm not sure it's a good idea to exceed the spec by as much as 3,3V/25%.
    Last edited by minim; 10-08-2018 at 10:21 AM.

  4. #4
    Flashaholic* FRITZHID's Avatar
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    Default Re: DIY Battery for Maxabeam

    Quote Originally Posted by minim View Post
    Thank you for checking. Maybe they.......

    ..... Another member I spoke with also had a servo on his going bad when trying a 4S pack so I'm not sure it's a good idea to exceed the spec by as much as 3,3V/25%.
    Yeah, that was me. One g2 i have will NOT run at all on 4s cell pack (other than rapid strobing and the other ran fine until one day the focus servo just up and seized. Be better to run 3s & 2-4p fit the extra runtime.
    I Got tired of looking for the light at the end of the tunnel so i lit that bitch up myself! Convoy s2 365nm, Maxa-Beam Gen II, 55w hid/100w incan Vector Twin, Amondotech n30, vss-3A, Reylight Ti Lan v3, Helius Sigma 9, astrolux s41 219, Shadow JM35, BLF GT,

  5. #5

    Default Re: DIY Battery for Maxabeam

    Quote Originally Posted by FRITZHID View Post
    Yeah, that was me. One g2 i have will NOT run at all on 4s cell pack (other than rapid strobing and the other ran fine until one day the focus servo just up and seized. Be better to run 3s & 2-4p fit the extra runtime.
    Yeah I won't risk $4-500 cost in parts on running it above what they recommend..

    You have a good point there sir with just accepting the possibility to not discharge them fully. I see from discharge graph on a Samsung 30Q that you are at approx 8.5wh of 10.2Wh total at 3.4volts. That's 83% of the capacity when counting 2.8V as end but thats low so its more like 90%. This is with 3A load. Comparing that to Panasonic ncr18650b 3400mAh cells they will give 6.2Wh at 3.4 volts so the lower total capacity is actually better. 83% isn't horrible and it will prolly make the cells last longer. Maybe a 3S6P would do the job. I have a 3S5P I built for my little girls toycar so I will test this first before I build one for the job

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