Donnie Posted October 3, 2016 Share Posted October 3, 2016 Hello team, I'm just wondering if anyone has any concerns about their deep cycle battery getting blasted with too many amps after boondocking for 3 or 4 days & running it down to the limit. Then starting the engine & heading for home.. I haven't clamped a meter on it yet as the thought just occurred to me.. So I thought I'd get some opinions. I'm not sure if the isolator has the ability to control what the regulator is telling the alternator to produce.. I'm running a diode style & not a solenoid type...& as you know they are potted & I'm not able to get inside.. I haven't decided if the voltage regulator is reading the truck battery or the coach battery.............I'll drag out the meter when it stops raining & start checking Anyone with this concern or any ideas on this matter............ I'd like your opinion............ TIA, donnie Quote Link to comment Share on other sites More sharing options...
Maineah Posted October 4, 2016 Share Posted October 4, 2016 (edited) The isolator is not a regulator it has no control over charge rate of either battery. There is a voltage loss of about .7 volts across the isolator due to the inefficency of the diodes that is why they have cooling fins but that effects both batteries the same way. The regulator reads the truck battery voltage only. Edited October 4, 2016 by Maineah Quote Link to comment Share on other sites More sharing options...
WME Posted October 4, 2016 Share Posted October 4, 2016 What type of battery?? Flooded cell max rate is around 10% of capacity, an AGM can deal with a 30% charge Quote Link to comment Share on other sites More sharing options...
zero Posted October 4, 2016 Share Posted October 4, 2016 21 hours ago, Donnie said: Hello team, I'm just wondering if anyone has any concerns about their deep cycle battery getting blasted with too many amps after boondocking for 3 or 4 days & running it down to the limit. Then starting the engine & heading for home.. I haven't clamped a meter on it yet as the thought just occurred to me.. So I thought I'd get some opinions. I'm not sure if the isolator has the ability to control what the regulator is telling the alternator to produce.. I'm running a diode style & not a solenoid type...& as you know they are potted & I'm not able to get inside.. I haven't decided if the voltage regulator is reading the truck battery or the coach battery.............I'll drag out the meter when it stops raining & start checking Anyone with this concern or any ideas on this matter............ I'd like your opinion............ TIA, donnie I don't think it is possible to overcharge with an automotive alternator. Cell voltage for your deep-cycle battery is not supposed to exceed 2.45 volts per cell when doing a rapid charge. That comes to 14.7 volts. I doubt the regulator in your alternator ever exceeds 14.2 volts. Main complaint with auto-alternators and large deep-cycle batteries is they get slightly undercharged, not overcharged. As far as your isolator and how it actually works? I have to admit ignorance here. The internally regulated Nippo alternator on Toyotas often uses a "remote voltage sensing" wire. That is supposed to get hooked to the 4th terminal on the isolator called the "exciter" terminal. I know for a fact that it does not "excite" anything with the usual-tech meaning of the word. So what the heck does it do? As I said, I do not really know. I mention this since I wonder if the 4th terminal allows the alternator to sense charge-voltage at the output of the isolator and therefore, compensate for the .7 voltage drop. Easy to verify with a voltmeter. Quote Link to comment Share on other sites More sharing options...
Maineah Posted October 5, 2016 Share Posted October 5, 2016 (edited) In the case of a more modern internally regulated alt on the newer Toyota's the B+ terminal has to see battery presence the "E" terminal is used to supply + voltage to the "B" terminal via the ign + feed. When a solid state isolator is installed the "B +" wire is not longer connected to the battery so the "E" terminal supplies the needed + voltage to the "B" terminal it "excites" the dormant "B" terminal. This is done thru a diode if it was a direct connect chances are you would not be able to turn off the engine because it would back feed the "E" terminal supplying 12 volt to the system. The entire isolator is nothing more than 3 diodes two carry high current one is for the "E" terminal. A diode is nothing more than a one way valve so the two connected to the batteries only allow power to the batteries but not from the batteries to keep them from discharging each other. the "E" diode only allows power to the "B" but not from the "B" terminal. I have "tricked" 3 terminal isolators into working by installing a diode between the B and ign wire at the alternator to do the same thing the e terminal would .The diodes are not 100% efficient so the loss becomes heat that is why they have cooling fins. Edited October 5, 2016 by Maineah Quote Link to comment Share on other sites More sharing options...
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