Couple of questions about DC-Dc charging
I've been thinking about adding a DC-DC charger now that I've added 400 amp hours of AGM batteries. There are lots of useful posts but I haven't run into a couple of things I'm curious about. One ...
Forum Discussion
The only reason I am engaging in this is for educational purposes :)
Again, keeping in mind the discussion if for an alternator that is not controlled via an ECU Engine Control Unit. But rather by its dedicated voltage regulator.
And for simplicity's sake, keep the discussion limited to "normal" RV usage with "normal" temperatures to avoid a needless blizzard of irrelevant temperature compensation numbers.
Unless an RV is "Hot Seat" operated, meaning driven day and night for weeks on end, any multi-stage voltage "steps" are ludicrous. The rig is simply not driven long enough in hours for voltage manipulation to matter. We're not talking about a manual wheeled battery charger here. Alternators are voltage regulated.
Start out from home with fully charged AGM batteries. Drive six hours to a campsite. Will the batteries be damaged with a 14.0 voltage sustained? Not only no, but hell no.
Leave the batteries connected day and night without using them, for a month or months with 14.0 volts. Will this be detrimental to the batteries? Not only yes, but hell yes.
Do you see the difference here? I hope so.
Used as a current limiter, the two hundred dollar converter does a worse job than an inherent current limiter. Twenty amps is pathetic. It becomes an absurd amount in a multi battery bank, if the alternator is used as a bulk recharging device.
It wouldn't see correction from 14.0 volts to say 14.4 voltage inside of eight hours of campsite continuous engine operation. Read this again. Still with me?
If a DC converter was designed for say 60 amp operation, then it presents a different issue. But it isn't and it doesn't.
So what good is a DC to DC converter with the OPs system?
Current limitation to protect the alternator from hours of high amperage operation in a superheated engine compartment.
The same limiting as a length of wire that costs $185 less. And can allow sixty amperes of recharging. How many DC converter dollars is that?
The extreme overkill amperage limitation is the DC converter's Achilles Heel.
It sort of is like lacing up a pair of hundred dollar Caterpillar boots to walk to the driveway mailbox.
Forget about heat and forget about wasted amperage with a current limiting length of fusible length wire. Both issues are negligible. Only worthy of theoretical discussions.
Again, keeping in mind the discussion if for an alternator that is not controlled via an ECU Engine Control Unit. But rather by its dedicated voltage regulator.
And for simplicity's sake, keep the discussion limited to "normal" RV usage with "normal" temperatures to avoid a needless blizzard of irrelevant temperature compensation numbers.
Unless an RV is "Hot Seat" operated, meaning driven day and night for weeks on end, any multi-stage voltage "steps" are ludicrous. The rig is simply not driven long enough in hours for voltage manipulation to matter. We're not talking about a manual wheeled battery charger here. Alternators are voltage regulated.
Start out from home with fully charged AGM batteries. Drive six hours to a campsite. Will the batteries be damaged with a 14.0 voltage sustained? Not only no, but hell no.
Leave the batteries connected day and night without using them, for a month or months with 14.0 volts. Will this be detrimental to the batteries? Not only yes, but hell yes.
Do you see the difference here? I hope so.
Used as a current limiter, the two hundred dollar converter does a worse job than an inherent current limiter. Twenty amps is pathetic. It becomes an absurd amount in a multi battery bank, if the alternator is used as a bulk recharging device.
It wouldn't see correction from 14.0 volts to say 14.4 voltage inside of eight hours of campsite continuous engine operation. Read this again. Still with me?
If a DC converter was designed for say 60 amp operation, then it presents a different issue. But it isn't and it doesn't.
So what good is a DC to DC converter with the OPs system?
Current limitation to protect the alternator from hours of high amperage operation in a superheated engine compartment.
The same limiting as a length of wire that costs $185 less. And can allow sixty amperes of recharging. How many DC converter dollars is that?
The extreme overkill amperage limitation is the DC converter's Achilles Heel.
It sort of is like lacing up a pair of hundred dollar Caterpillar boots to walk to the driveway mailbox.
Forget about heat and forget about wasted amperage with a current limiting length of fusible length wire. Both issues are negligible. Only worthy of theoretical discussions.
