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Post by brianrhea on Aug 8, 2017 19:33:53 GMT -8
The best location for mounting my 20-amp Rover controller would require about 20' of wire. I contacted Renogy customer support and got the following:
I completely understand their official position, but I'm curious how much of this is Renogy giving themselves some liability cover vs "no seriously, don't go more than 10 feet from the battery to the controller."
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Post by rabird on Aug 9, 2017 3:18:37 GMT -8
this is up to you and how well you care for your battery(ies). 10' of 10 awg @ 10A yields a voltage drop of 0.2 volts. 20' of 10 awg @ 20A yields a voltage drop of 0.822 volts. www.genuinedealz.com/voltage-drop-calculatorDo as ya like, might even bump 'boost' voltage up to account for some voltage drop (if the rover is adjustable), monitor you battery, readjust and monitor ... Now reconsider the 'best' mounting location, for me it would be CLOSE to the battery(ies). Another option is to buy batteries more often. There's many a way to abuse a battery beside not FULLY charging. |
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Post by brianrhea on Aug 9, 2017 10:40:22 GMT -8
Thanks rabird!
Out of curiosity (I'm still a newb and learning about electricity now that I've entered the solar world), why do your two examples switch from @10a to @20a?
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Post by brianrhea on Aug 9, 2017 11:25:38 GMT -8
Also, is the primary concern that because of the voltage drop the battery never has a chance to get fully charged before I start drawing from it again?
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Post by cosmicboss on Aug 9, 2017 11:53:43 GMT -8
The primary concern is fire. The voltage drop is because of resistance in the wire, kind of akin to friction in a water pipe. The problem with voltage drop in too long a wire is that the drop (or loss) is due to heat. I other words your are turning your wire into a heating element and thus there is a danger of it catching fire.
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Post by rabird on Aug 9, 2017 12:51:42 GMT -8
Also, is the primary concern that because of the voltage drop the battery never has a chance to get fully charged before I start drawing from it again? you are correct, repeated undercharge yields a loss in capacity, so does deep discharges, so does leaving a battery discharge for any length of time. so ideally you use the battery and fully recharge ASAP to limit damage. RVers often times cycle their batteries between 50-80 or 50-90 % since it takes a long time to get fully charged and generator run time is limited or fuel costs ... Eventually they find utility power or solar and FULLY charge and occasionally equalize (get the last bit of chemical reaction reversed). If you have plenty of capacity you won't notice this for year(s), but remember 95% full is not 100% full! and lead acid likes 100% full. the two scenarios are just examples, often times I see 1% or 2% voltage drop for controller to battery, so if charge voltage is 14.8v then 1% is ~0.15v. many ways to abuse batteries, take care of them or replace them regularly. www.trojanbattery.com/tech-support/battery-maintenance/ |
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