Protecting nav electronics during equalize phase?

SFBaySailor
SFBaySailor Registered Users Posts: 2
in Solar Beginners Corner #1
Hopefully this has already been asked and answered, but I couldn't find anything relevant by searching, and with almost 3,000 threads to date I hope to not have to plod through them all, page by page.

My concern is this: when periodically equalizing my battery by a 17V panel through a controller, when the voltage is reaching levels around 15+, is there any need (or way) to protect sensitive navigational electronics from the excessive voltage, or do they all need to be turned off?

Rather than rehash this if it's already been answered by someone with expertise, I'd be happy to simply be pointed to an earlier thread or to a reliable outside document. Thanks.
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Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Protecting nav electronics during equalize phase?

    Welcome to the forum.

    You're quite right to be concerned about this as there are a lot of "12 VDC" devices that do not like and will not take 15+ Volts.

    Best case scenario: you shut off all loads when equalizing.

    Second best: split the battery bank if possible (as in two parallel 12 Volt sections) and EQ one half at a time while the other keeps things running.

    Third place: Voltage regulation on all sensitive equipment.

    Fortunately you shouldn't have to EQ often so shutting things down for an hour or two once a month could be viable.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #3
    Re: Protecting nav electronics during equalize phase?

    many electronic items use standard parts ratings and most would start at about 16v. i would not advise going to that 16v point as tolerances on that rating i would not trust. you would need to go over the manuals for all of the connected equipment to see what they a rated to and if the equipment does not list such a voltage rating i would contact the company for such a specification. odds are most of your stuff will probably be fine at 15v, but you are correct to question.

    shutting things off is always an option, but it may be inconvenient for you at the time to do so for some items. there is a way to lower the voltage and it is by using a diode placed in series in one of the leads to the equipment. (noting that if the polarity is wrong that no power will pass and you simply turn the diode around) it must be able to pass the current requirements of the load presented to it, but it will drop the voltage by about .5v-.75v. if that is too much for that item to run with during semi drained states of charge on a battery with no charging source to up the voltage then you could place a switch across the input and output of the diode. while closed it will allow the full voltage, but opening the switch to off will not disconnect the power as it would now go through the diode.

    note that this is a bit of a pain to do with high current drawing items as the diode will often need a heat sink in large draw cases. not sure if radio shack still sells 6a barrel diodes or not, but i would not hesitate to parallel 2 or possibly 3 even though this can lead to failure of the diodes in some cases. but hey, they're often cheap enough.
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  • SFBaySailor
    SFBaySailor Registered Users Posts: 2
    #4
    Re: Protecting nav electronics during equalize phase?

    Thanks for the quick responses. You've confirmed my suspicion. Funny I've never seen this in print before.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #5
    Re: Protecting nav electronics during equalize phase?
    SFBaySailor wrote: »
    Thanks for the quick responses.

    no problem.

    You've confirmed my suspicion.

    good you thought to ask.

    Funny I've never seen this in print before.

    i believe it was mentioned in passing in some threads. we have no problem addressing it again directly though.

    think of it this way, most items connected to cars, boats, rvs, etc. must have some leeway in the voltage requirements as most charging systems will have excursions high and low. these excursions may be tighter than the 15v you are proposing due to a particular battery's requirements particularly when being eqed. good manufacturers of electronics will state in their manuals or at least on the box itself the voltage requirements to properly run their stuff. if they don't do this the manufacturer could be held liable for any failures resulting in a new piece of merchandise or their money back at a minimum. in any case, we don't want to go the legal routes as we just want our stuff to mesh well and function and is the nature of your question in the first place and in the absence of any voltage requirements with no luck in getting that info for something i would assume it to not function well at 15v or beyond and some items it may actually be lower than this.

    as an example i have a ham radio that lists its voltage requirements to be "DC 13.8 V ±15%." that means they say it's good up to 15.87vdc and a low of 11.7895v.
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