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
:R
I answered specific questions asked by someone with a specific system.
Some of the answers I read in this thread are (to be modest about it), are wrong. Or worse yet, illogical. Keep reading...
This gets even better:
Less than one half of one percent of RV'ers drive over "X" number of hours per day. They either duck into an RV park or boondock overnight. Both of which discharge the house battery bank a certain amount.
It would be impossible to overcharge an AGM battery using the vehicle charging system within this type of operation
Yet it would be guaranteed that the alternator would charge at full rated capacity. Something he recognizes as being a significant problem.
He has 400 amp hours of AGM batteries. Divide that into 40. Ten hours of theoretical charging, which cannot happen because of battery increasing resistance as it fills. To add insult to injury, a ten ampere charge rate violates a simple AGM battery recharge rule, which is a 20% minimum of total 20 amp hour rate minimum charge rate - which is 20 amperes per battery in the case of the OP's question.
And even that is illogical given the total missing amp hours missing in a 50% discharged scenario. Getting the picture? Why deal with an issue using illogic? Current limiting the alternator is 99% the issue in this case. Again my answer was and is addressing a specific set of circumstances.
Basically this...the 40 ampere power supply means limiting the rig to a ten ampere recharge rate. 40 ampere hours per battery in a ten hours continuous drive.
I looked up the price of a Renology 40 amp power supply. Basically it's two hundred dollars.
To perform all of the above. An eighty ampere DC power supply would provide 20 amperes to each battery. But now the price has jumped to four hundred dollars.
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With different batteries, or an ECU controlled charging system the above specifications become obsolete. As they would be if the rig were driven hot-seat big rig style for sixteen or twenty hour stretches.
The answers I have read would remind me of the justification to buy an eight hundred dollar set of expedition grade boots for a visit to the mall.
My own thoughts are to substitute wasted money for a substantial increase in solar charging limits or generator recharging potential.
Keep in mind the specific charging system and the specific bank type and size.
Intelligent analysis, planning and execution cannot "Go Out Of Style"
I answered specific questions asked by someone with a specific system.
Some of the answers I read in this thread are (to be modest about it), are wrong. Or worse yet, illogical. Keep reading...
- The original poster asked a specific question about a specific alternator
- The Ford 3, 4, or 6G alternator
- These alternators never used the ECU for voltage regulation
- They use an integral B field excitation circuit
- His question was principally how to limit current to prevent alternator overheating
This gets even better:
Less than one half of one percent of RV'ers drive over "X" number of hours per day. They either duck into an RV park or boondock overnight. Both of which discharge the house battery bank a certain amount.
It would be impossible to overcharge an AGM battery using the vehicle charging system within this type of operation
Yet it would be guaranteed that the alternator would charge at full rated capacity. Something he recognizes as being a significant problem.
He has 400 amp hours of AGM batteries. Divide that into 40. Ten hours of theoretical charging, which cannot happen because of battery increasing resistance as it fills. To add insult to injury, a ten ampere charge rate violates a simple AGM battery recharge rule, which is a 20% minimum of total 20 amp hour rate minimum charge rate - which is 20 amperes per battery in the case of the OP's question.
And even that is illogical given the total missing amp hours missing in a 50% discharged scenario. Getting the picture? Why deal with an issue using illogic? Current limiting the alternator is 99% the issue in this case. Again my answer was and is addressing a specific set of circumstances.
Basically this...the 40 ampere power supply means limiting the rig to a ten ampere recharge rate. 40 ampere hours per battery in a ten hours continuous drive.
I looked up the price of a Renology 40 amp power supply. Basically it's two hundred dollars.
To perform all of the above. An eighty ampere DC power supply would provide 20 amperes to each battery. But now the price has jumped to four hundred dollars.
-----------------------------------------------------------------------------------------------------------------
With different batteries, or an ECU controlled charging system the above specifications become obsolete. As they would be if the rig were driven hot-seat big rig style for sixteen or twenty hour stretches.
The answers I have read would remind me of the justification to buy an eight hundred dollar set of expedition grade boots for a visit to the mall.
My own thoughts are to substitute wasted money for a substantial increase in solar charging limits or generator recharging potential.
Keep in mind the specific charging system and the specific bank type and size.
Intelligent analysis, planning and execution cannot "Go Out Of Style"
