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Thread: 100 amp inline diode

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    Default 100 amp inline diode

    My truck is a 24v vehicle and up to recently I also had an additional 12v alternator on the engine to charge my auxiliary 12v battery that runs my fridge etc. The truck has ignition lights for the two systems - so if either was not charging the applicable charging light would come on.

    Now I have taken the 12v alternator off the engine as it was mounted low and required a bit of maintenance and is an extra strain on the engine. In its place I am now using a 24v to 12v DC/DC 60 amp three stage battery charger. Ideally I would like the old 12v ignition light to work the same way as it did when the alternator was in place - that is, light on when ignition is on and there is no charge to the battery and light off when charging. I have a small electronic unit which connects to the output of the charger that can do this but the issue is that if the DcDc charger is not working, power flows back from the battery so the 12v ignition light does not light as the electronic unit is getting power from the battery.

    One way to fix this is to put a 100amp diode (the charger is 60amp) in the cable run from the charger to the battery so power from the battery cannot flow back.

    I have googled 100amp diodes but only come up with wholesalers selling in bulk - any ideas where I might buy a big 100 amp diode?

    Thanks

    Garry
    Last edited by garrycol; 06-03-18 at 02:14 PM.



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    Quote Originally Posted by garrycol View Post
    ...any ideas where I might buy a big 100 amp diode?
    One problem that you may run into is that such high current diodes have large forward voltage drops, in some cases up to 2 Volts.
    If that isn't a problem try from Element 14. Available in one off quantities with a lead time of 6 - 7 business days.
    It is a dual 50 amp package that just needs the two anodes tied together for 100 amps.
    "Any sufficiently advanced technology is indistinguishable from magic."

    - Arthur C. Clarke

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    Great - thanks for that - unfortunately any sort of major voltage drop means the battery will not charge correctly and a 2v drop means the battery will not charge more than about 50% which is too low. I didn't realise a diode would suck out so much voltage - I need to rethink this.

    Thanks

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    If the DCDC is doing a good job of charging the 12v side then I would be looking at making your little warning light circuit more sensitive. Maybe a small relay which engages when a certain voltage is reached , like 13.2v or something. The relay can then trigger the warning light.
    Last edited by VroomVroom; 07-03-18 at 07:45 AM.

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    Yes - thanks - something to consider - yes I can put in a warning light when the system voltage is getting low. In view of the voltage loss caused by diodes I might have to look at that.

    Cheers

    Garry

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    One of might be suitable.

    RS have next business day free freight - well, they did the last time I used them.
    Never stand under a shadow that's getting bigger

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    We

    What I did was buy volt/amp led panel meters from alibaba, cheap, proven reliable over couple years, shows at glance batt/s health.. fitted to all my vehicles.

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