Renogy DCC30S/DCC50S 12V 30A/50A DUAL INPUT DC-DC ON-BOARD BATTERY CHARGER WITH MPPT

[Arbee]

Why do you suppose that either of these devices, which charges house and starter batteries from solar in that priority....

and when the vehicle is cranked, charges the starter and house batteries (i.e. flipped) in that order, only be concerned with the battery type of the house battery?

Is it because the charge of the starter battery off a the solar panel (a secondary task) is likely to be very generic, and this not concerned with battery type?

https://www.renogy.com/dcc30s-12v-30a-dual-input-dc-dc-on-board-battery-charger-with-mppt/

https://www.renogy.com/dcc50s-12v-50a-dc-dc-on-board-battery-charger-with-mppt/

In Renogy's tutorial below they use a Lead Acid starter battery and a Lithium Iron Phosphate house battery. They configure the device, it seems, for only the Lithium Iron Phosphate house battery.

Thanks

P.S. getting Renogy to pick up a phone or return an email right now (COVID) is quite challenging, much that I tried to reach out to them. I thought that perhaps one of you might know.

 

[snoobler]

Because most if not all starter batteries are FLA/AGM due to the fact that LFP can't handle starting currents. It's designed with a typical 12V vehicle starting system in mind.

This device is not for the starter battery, it's for the "house" battery, so it only is configured for the "house" battery.

 

[riker1]

Hi

maybe I am missing something .

but what is the difference with between a charging booster and the

Renogy DC DC Charger with MPPT?​

If I use a Renogy DC DC I do not need the charging booster, right?

 

[snoobler]

Hi

maybe I am missing something .

but what is the difference with between a charging booster and the

Renogy DC DC Charger with MPPT?​

If I use a Renogy DC DC I do not need the charging booster, right?

What is the "charging booster?"

 

[riker1]

Hi ,
maybe it is the same as B2B DC DC charger?
Need to charge one DC battery from another?
Our DC/DC BOOSTERS

I understand that the issue is the location, in RV or Trailer. Trailerwiring can not be use for 50A charging booster, DC DC Charging, right?

 

[Arbee]

@riker1, the DCC50S or DCC30S is two devices in one: a DC - DC charger (which by the way can be bidirectional--more on this in a moment) and a MPPT Solar Controller.

For illustration check out our Administrator's video:

This device can take energy from a solar panel and charge a battery apart from the one under a vehicle hood (house battery), and if there is surplus power in such daylight hours, also charge the battery under the hood (the starter battery.)

It can also, with the engine on, accept current from the starter battery (backed up by the alternator) to charge the house battery.

 

[riker1]

@riker1, the DCC50S or DCC30S is two devices in one: a DC - DC charger (which by the way can be bidirectional--more on this in a moment) and a MPPT Solar Controller.

For illustration check out our Administrator's video:

This device can take energy from a solar panel and charge a battery apart from the one under a vehicle hood (house battery), and if there is surplus power in such daylight hours, also charge the battery under the hood (the starter battery.)

It can also, with the engine on, accept current from the starter battery (backed up by the alternator) to charge the house battery.

But you think I can use this in the trailer, not sure about the input wiring? will this work via 7 pin trailer plug?

 

[Arbee]

@riker1 I'd have to suggest that the gauge of the wiring in most 7 pin trailer plugs is inadequate, both due to the lengths of wire being run and amperage, to have a trailer and tow vehicle battery share power with one another as done with this product.

Well, it's not so much the batteries sharing power with each other as it is the tow vehicle's alternator and the trailer vehicle's solar panel(s).

Dedicated cable, terminated with Anderson plugs at the location where tow vehicle meets the trailer, would probably be best.

Additionally, this device seems to work best when it knows whether the engine is cranked, even if its alternator is not one of the more recently produced "smart variety" ones.

Here's a situation where cable not thicker than that in most 7 pin wiring harnesses' wires would suffice to provide this information to the product, but those 7 wires are normally assigned other tasks.

 

[Arbee]

I may be straying from the thread slightly but - I have a DCC30S, 2 x 100Ah lifepo4 batteries, and a question about shore power conversion. I'm not using solar just yet. I want to get a converter to charge from shore power. That seems to be what Will was doing in a Youtube video. Am I understanding right? I can just hook the converter to the Renogy + alternator input? And the amps and the charge stages of the converter won't matter much because the Renogy will control the output profile? If that the case I think it would be nice to get a simple single stage charger but I don't see anything out there but 3 and 4 stages.

@stinky : this came up before I believe (if I understood your question correctly) and I wrote of "an" answer here

https://diysolarforum.com/threads/renogy-dc-dc-charger-w-mppt.1406/post-214659

Let me try this in simplified terms so that we can both be sure that we are talking about the same issues.

First, you acquired the DCC30S (I hope) because at some point you would like to have some energy source (solar, shore power, wind turbine, heck: squirrel in exercise cage) charge your house battery, and with any excess, trickle charge your starter battery. Notice I said trickle charge (not fully charge) as it regards the starter battery, i.e. prevent the starter battery voltage from dropping due to simply the forces of time, not power draw on it while the engine is off and not charging the starter battery.

Well, for argument sake, you could have a shore powered charger that converts 120 A/C into suitable DC power in the 12volt range, not to exceed 30 amps (the limits of the DCC30S) connected to the top two terminals on the DCC30S, where a solar source (that you currently don't have) and its ground would normally go. I can't imagine the DCC30S cares what's feeding it power on these two terminals as long as that current is in the proper DC range. And that shore power will charge your house battery and with any excess after fully charging that house battery, trickle charge your starter battery.

I can't help but think that your idea was to directly connect the shore charger to the starter battery. That, according to the manual, would seem to work (under the right conditions) as well. https://www.renogy.com/content/RBC3050D1S-G1/RBC3050D1S-Manual.pdf I think it would be much like, as page 16 of the linked manual, running your vehicle during nighttime (where ultimately the alternator would supply power to the starter battery, and from it, to the house battery) except your power source (with the engine off) would be shore power rather than the vehicle's alternator.

And I imagine that how and when this shore power flows to the house battery would depend upon whether your vehicle has a smart or traditional alternator, and whether--if you have a smart alternator--you have hooked up the IGN (ignition) signal wire of page 11.

At the risk of pointing out that which may be known, later model vehicles have an alternator which varies the voltage it supplies to the starter battery while traditional alternators pump a constant voltage. Smart alternators, not providing more voltage than the starter battery needs, tax the engine less and save fuel.

The chart on page 16 talks about when current from the alternator (i.e. the starter battery fed by the alternator, or in your case the shore charger) will charge the house battery.

I think I prefer your shore charger connecting to the DCC30S, not the starter battery's terminals, unless you are running appliances off the starter battery with the engine not running. Provided your starter battery and alternator are fine and you tend to only tax the starter battery with the engine on/alternator running, trickle charging of the starter battery should typically be all you need.

Of course in COVID we seem to be running our engine's less, and this may have an impact on the primary location of the shore charger, particularly in cold weather.

I hope this helps.

 

[Alphacarina]

Why do you suppose that either of these devices, which charges house and starter batteries from solar in that priority....

and when the vehicle is cranked, charges the starter and house batteries (i.e. flipped) in that order, only be concerned with the battery type of the house battery?

Is it because the charge of the starter battery off a the solar panel (a secondary task) is likely to be very generic, and this not concerned with battery type?

*Usually* the starter battery is connected directly to the alternator, so when the engine is running, that's how it gets it's charge. The DC to DC is *usually* set up to conform to the type of house battery you want to charge, because that's why you bought the DC to DC - To apply the specific charge parameters the house battery (usually lithium) needs because the alternator isn't capable of doing that

. . . . Unless Renogy is having you disconnect the starter battery from the alternator when you install their DC to DC??

Don

 

[stinky]

Thanks for the reply. You write well. Let me try fill in some blanks. First you mention smart alternators. I'm dealing with a 2007 GMC. I could be wrong but I very much doubt that it's very smart. Not sure where you got the idea that I was thinking of hooking the converter to the starter battery. Actually 'not' having that connection is a problem I'm trying to sort out. You'll see what I mean in the last paragraph.


Thanks for the link to the Renogy manual. Somehow missed that before. I see the mention of maximum amps - "The maximum alternator charging for the DCDC30 is 30A". That seems like a curious stipulation because I know my alternator is around 150A and I would imagine it will want to send at least half that to the house battery most of the time. I've never heard of a way to limit the alternator output? Also I never heard of anything 'supplying' too many amps. 'Drawing' too many yes. I always thought amps were like vitamin C. What doesn't get used gets tossed. No? I wonder if the 30A max is not just a statement of the DCC30S output.


I'm sorta looking at a 55A converter. A Gopower GPC-55-MAX specifically. I am particularly fond of Gopower products. I've had a couple and they have been very reliable. Also their customer service is exceptional. On the GPC-55-MAX there is an option (if I'm understanding right, and I'm waiting now for clarification) to forgo the multistage profile and set a fixed voltage output. That seems to me like a sensible option if I want it to emulate an alternator output. Yes? I haven't checked my alternator output but I imagine it will most or less constant at 14+V. That's within the fixed voltage settings of the GPC-55-MAX.


As to using the PV+ terminal for the converter I would worry that might be some circuitry specific to PV there that wouldn't be compatible. Also I will eventually be adding panels so I think I may as well leave that input alone.


Here's what I think is safe - I can connect the converter to the alternator input and flip the 40A breaker going to the alternator off when I connect to shore power. Perhaps an 'either or switch' would be better. And maybe neither is necessary. It's an unanswered question as to whether the current from the converter would pose some problem if hooked to the cable from the alternator. The Renogy isolates the house from the starter batteries but there would be no isolation if I connect both the converter and the alternator to the same terminal and I don't know if that would be a problem. Probably not so long as I wasn't connect to shore power with the engine running. Be great if you or someone else could clear that up for me. If not I think a disconnect or transfer switch for the starter battery / alternator would eliminate any potential problem. It occurs to me that the alternator has a regulator but the converter doesn't. It might be safer not to let the converter feed the alternator/starter battery.

 

[Arbee]

Thanks for the reply. You write well. Let me try fill in some blanks. First you mention smart alternators. I'm dealing with a 2007 GMC. I could be wrong but I very much doubt that it's very smart. Not sure where you got the idea that I was thinking of hooking the converter to the starter battery. Actually 'not' having that connection is a problem I'm trying to sort out. You'll see what I mean in the last paragraph.


Thanks for the link to the Renogy manual. Somehow missed that before. I see the mention of maximum amps - "The maximum alternator charging for the DCDC30 is 30A". That seems like a curious stipulation because I know my alternator is around 150A and I would imagine it will want to send at least half that to the house battery most of the time. I've never heard of a way to limit the alternator output? Also I never heard of anything 'supplying' too many amps. 'Drawing' too many yes. I always thought amps were like vitamin C. What doesn't get used gets tossed. No? I wonder if the 30A max is not just a statement of the DCC30S output.


I'm sorta looking at a 55A converter. A Gopower GPC-55-MAX specifically. I am particularly fond of Gopower products. I've had a couple and they have been very reliable. Also their customer service is exceptional. On the GPC-55-MAX there is an option (if I'm understanding right, and I'm waiting now for clarification) to forgo the multistage profile and set a fixed voltage output. That seems to me like a sensible option if I want it to emulate an alternator output. Yes? I haven't checked my alternator output but I imagine it will most or less constant at 14+V. That's within the fixed voltage settings of the GPC-55-MAX.


As to using the PV+ terminal for the converter I would worry that might be some circuitry specific to PV there that wouldn't be compatible. Also I will eventually be adding panels so I think I may as well leave that input alone.


Here's what I think is safe - I can connect the converter to the alternator input and flip the 40A breaker going to the alternator off when I connect to shore power. Perhaps an 'either or switch' would be better. And maybe neither is necessary. It's an unanswered question as to whether the current from the converter would pose some problem if hooked to the cable from the alternator. The Renogy isolates the house from the starter batteries but there would be no isolation if I connect both the converter and the alternator to the same terminal and I don't know if that would be a problem. Probably not so long as I wasn't connect to shore power with the engine running. Be great if you or someone else could clear that up for me. If not I think a disconnect or transfer switch for the starter battery / alternator would eliminate any potential problem. It occurs to me that the alternator has a regulator but the converter doesn't. It might be safer not to let the converter feed the alternator/starter battery.

@stinky: I got the idea that you were thinking of hooking the converter to the starter battery from this line you wrote

"I can just hook the converter to the Renogy + alternator input?" and "alternator input" stuck in my head--as if you were inputting your power into the same location the alternator feeds: in other words the starter battery's terminals.

The DCC30S is capable of accepting less amps than the alternator can deliver. And by the way, with energized inputs on the alternator terminals of the DCC30S AND (energized) solar inputs on the solar terminals of the DCC30S at the same time (along with each connected to the one ground terminal) that amperage is cut in half to 15 amps for each of these two sources(top of page 17 of the manual.)

It's 25 amps each for these two sources for the DCC50S product.

Let me speak to "limiting amps" as you phrase it for a second. Say you have a 20 amp circuit in your house, but connect to it only an minimal current drawing AM/FM transistor radio from the 1970's. Think of the 20 or less amps as that that is capable of being provided on the line, and as being "pulled" by the radio, and that 20 amps is the limit of what the fuse or circuit breaker will allow, given the wires (or in this case internals of the DCC30S) are capable of handling.

Don't think of the amps as being pushed down the metaphorical "appliance's throat," not unless the appliances demands it.

So the Gopower GPC-55-MAX can provide up to 55 amps max from what I see--at least in one of more stages of its 4 stage charging algorithm. I'm not saying its use will be dangerous to use (I don't know) but sending an email to Renogy might be in order. I admit to not reading further into its four stages, the types of batteries it is compatible with, and the type of battery your house battery is.

Bare in mind though that you would be (assuming you hook the Gopower GPC-55-MAX up to the solar terminals of the DCC30s) connecting a device (the Gopower GPC-55-MAX) with its own logic for interrogating your house battery and determining what charge state of its 4 to be in, not directly to that battery, but to the DCC30S: complete with its own logic of charging your house battery based upon its type and state of charge (SOC.)

Maybe you just want to go with a shore charger capable of delivering no more than 30 amps constantly and let the DCC30S decide how much of that to draw based upon the house battery type you have selected on your DCC30S, and the DCC30S' conclusion about the state of charge your house battery based on its own interrogation of the battery's power. Or maybe you want to hook the Gopower GPC-55-MAX directly up to the house battery....but then the Gopower GPC-55-MAX won't trickle charge your starter battery.

I am predicting that the DCC30S will only draw, at max, 30 amps from any shore charge you go with---15 if the engine is cranked (15A from the alternator and 15A from you connecting the Gopower GPC-55-MAX (or some other shore charger) into the solar terminals of the DCC30S. Of course connecting to shore power and cranking the engine (to produce this 15A limitation on each input) is only consistent with the vehicle engine being cranked in your driveway.

If you were to plug the Gopower GPC-55-MAX into the starter battery, (which you don't suggest is your route, or one I think want to take) the DCC30S may see none of it's current unless the starter battery's voltage, consistent with the chart on the top of page 16 of the manual, exceeds 13.2V for 15 seconds.

There are other ways to charge your house and starter batteries as I suspect you are aware, especially if use of a solar panel is not in your plans. But using a shore charger in place of a solar panel allows, with the DCC30S, for you to charge these two batteries, and when on the road, and the shore power is not hooked up, have the alternator charge these same two batteries.

 

[stinky]

Sorry about the shorthand, by 'alternator +' I meant to indicate the alternator positive terminal of the Renogy.


I saw that mention in the manual about how the Renogy allocates equally from PV and alternator, with preference to PV if I got it right. That's not a concern right now as PV is at the end of long line of other issues to be dealt with.


I think you're saying the same thing I am. That the Renogy will only put out 30A max period. And then only if the house battery 'wants' it. Gopower makes a 35A unit with the same basic design. I don't think there is any harm in providing 55A. What I don't know is if there is any advantage. The price difference is only $30. It may be that I could use the extra amps at some point. Could trade up to a bigger B2B. As you suggest I could bypass the Renogy and put the 55A directly to my house or starter battery. (That actually won't happen for a variety of reasons.) Or that it could be better for the converter not to be running at maximum output. As a rule it seems like a good plan not to push any device to its limits. I'll quiz Gopower about that.


The Gopower is not 4 stage, it's 3. It says 4 on Amazon but it's not. And it's not programmed for lithium. AGM, SLA and etc. I was about to discard it as an option until I realized that the Renogy would provide the lithium profile. And the Gopower has the ability to deliver a fixed output voltage adjustable 13Vdc to 16.5Vdc. So that makes it a dumb charger and to my thinking a good stand in for an alternator.


There is still some trepidation about using the PV+ for the converter. I don't know if there is different circuitry behind that input. I'll mull over the advantage of having the convertor emulate PV for the sake of trickle charging the chassis battery. There must be some difference in the circuits from the PV to the ALT if PV trickle charges the chassis battery. Anyway, no upside that I can see if the only way it comes into play is by taking some load away from the alternator parked in my in my driveway with the motor running.


I'm just trying to think this through and asking a lot of questions to anyone who might have insight to offer. I'm curious to know if you think I'm actually better off with the 35A model. And what you think of my plan to use some sort of transfer switch to disconnect the alternator when I go to shore power.

 

[mkaye]

Thanks for the link to the Renogy manual. Somehow missed that before. I see the mention of maximum amps - "The maximum alternator charging for the DCDC30 is 30A". That seems like a curious stipulation because I know my alternator is around 150A and I would imagine it will want to send at least half that to the house battery most of the time. I've never heard of a way to limit the alternator output? Also I never heard of anything 'supplying' too many amps. 'Drawing' too many yes. I always thought amps were like vitamin C. What doesn't get used gets tossed. No? I wonder if the 30A max is not just a statement of the DCC30S output.

If your alternator is 150A, don't expect that it could send 1/2 that current to a battery under any conditions
that alternator is meant to charge your engine battery back up after starting the engine, so maybe lots of current for a few minutes and then tapering off as the engine battery voltage rises and the internal resistance of the LA battery limits current
if you were able to draw 75A from your alternator to charge an LFP battery for any length of time the alternator would certainly overheat and self destruct in a very short period of time
they are self-cooling and not designed for continuous charging
the DCC30S will limit the alternator output current to 15A, the input from the alternator will be higher depending on the state of your engine battery
i.e. if the engine battery is fully charged the alternator will probably be near minimum voltage of 13.6V, the DCC30S will have to boost this to 14.4V and draw more current to accomplish this
the end result is the alternator may still go up in smoke, especially if you idle for any length of time (on a hot day) when the LFP battery is charging

just a reminder to monitor your alternator temp as you are testing the system

 

[stinky]

I don't know empirically how many amps an alternator needs for general purposes, lights, plugs and etc. I've been advised that on the whole they are sized with overhead and that I can expect about half the output to be available to the house batteries. Maybe I've been mislead. I've also been told that the condition of the alternator makes a difference to its output. I would have liked to have gotten the DCCS50 but given that I am not sure about the condition of my alternator I decided it would be safer to settle for 30A. I believe that is also a 'kinder' charge rate.
I have not sorted out the workings of the Renogy. You say it will limit current from the alternator to 15A. I would hope that is when there is a PV current and that it would otherwise take 30A from wherever it can get it. I'd like to put these questions directly to Renogy but they have phenomenally poor customer service. I have yet to get any response to email. I've never waited more than a day or 2 for response from Gopower. Sometimes email almost at chat speed.

 

[stinky]

Just got this back from Gopower in a matter of minutes after asking.
"Yes you can run the GPC chargers continually on the fixed voltage output. 14.6 volts seems a little high but if that’s the input voltage their battery requires then that is what you can set it at. You cannot dial the amperage output back on the GPC chargers like that but I would agree with you that running a device below full capacity extends its life."

 

[Arbee]

If your alternator is 150A, don't expect that it could send 1/2 that current to a battery under any conditions
that alternator is meant to charge your engine battery back up after starting the engine, so maybe lots of current for a few minutes and then tapering off as the engine battery voltage rises and the internal resistance of the LA battery limits current
if you were able to draw 75A from your alternator to charge an LFP battery for any length of time the alternator would certainly overheat and self destruct in a very short period of time
they are self-cooling and not designed for continuous charging
the DCC30S will limit the alternator output current to 15A, the input from the alternator will be higher depending on the state of your engine battery
i.e. if the engine battery is fully charged the alternator will probably be near minimum voltage of 13.6V, the DCC30S will have to boost this to 14.4V and draw more current to accomplish this
the end result is the alternator may still go up in smoke, especially if you idle for any length of time (on a hot day) when the LFP battery is charging

just a reminder to monitor your alternator temp as you are testing the system

Your points about monitoring the alternator are well received.

That said, is was always my understanding that the DCC30/50S product would charge the house battery from the starter battery when that starter battery, consistent with the manual, exhibited certain defined voltages levels for certain durations--and if a smart alternator was present to charge the starter battery, the IGN ignition wire was installed on the DCC30/50S.

It was my understanding, perhaps only conceptual, that the DCC30/50S has no idea of an alternator's existence per se. In other words plug a fully charged battery into the terminals on the DCC30/50S that accept the starter battery, and if necessary draw another pair of wires from that battery to the IGN terminals on the DCC30/50S, and provided those voltage tests I describe are met, that battery which was just introduced will charge the house battery.

The alternator's role--and mind you it is critical--was one that I always saw as something "technically agnostic" (i.e. the DCC30/50S doesn't know or care about) and whose purpose was solely to replenish the starter battery's loss of power from energizing various vehicle loads, one of which possibly being the DCC30/50S.

 

[Arbee]

Sorry about the shorthand, by 'alternator +' I meant to indicate the alternator positive terminal of the Renogy.


I saw that mention in the manual about how the Renogy allocates equally from PV and alternator, with preference to PV if I got it right. That's not a concern right now as PV is at the end of long line of other issues to be dealt with.


I think you're saying the same thing I am. That the Renogy will only put out 30A max period. And then only if the house battery 'wants' it. Gopower makes a 35A unit with the same basic design. I don't think there is any harm in providing 55A. What I don't know is if there is any advantage. The price difference is only $30. It may be that I could use the extra amps at some point. Could trade up to a bigger B2B. As you suggest I could bypass the Renogy and put the 55A directly to my house or starter battery. (That actually won't happen for a variety of reasons.) Or that it could be better for the converter not to be running at maximum output. As a rule it seems like a good plan not to push any device to its limits. I'll quiz Gopower about that.


The Gopower is not 4 stage, it's 3. It says 4 on Amazon but it's not. And it's not programmed for lithium. AGM, SLA and etc. I was about to discard it as an option until I realized that the Renogy would provide the lithium profile. And the Gopower has the ability to deliver a fixed output voltage adjustable 13Vdc to 16.5Vdc. So that makes it a dumb charger and to my thinking a good stand in for an alternator.


There is still some trepidation about using the PV+ for the converter. I don't know if there is different circuitry behind that input. I'll mull over the advantage of having the convertor emulate PV for the sake of trickle charging the chassis battery. There must be some difference in the circuits from the PV to the ALT if PV trickle charges the chassis battery. Anyway, no upside that I can see if the only way it comes into play is by taking some load away from the alternator parked in my in my driveway with the motor running.


I'm just trying to think this through and asking a lot of questions to anyone who might have insight to offer. I'm curious to know if you think I'm actually better off with the 35A model. And what you think of my plan to use some sort of transfer switch to disconnect the alternator when I go to shore power.

No worries about the "alternator +" lingo. Things get lost in translation on forums (this one and others) all the time.

It's nothing to do with the forum: just the nature of written communication.

As long as the PV (i.e. the terminals on the DCC30/50S) to which a solar panel would normally be connected to "see" power, true, that power source will be primary, and have as its primary mission the task of charging the house battery (middle of page 15 of the manual.)

Yes: the DCC30S will only put out 30 amps max; the DCC50s 50 amps max. This can be provided by one energy source, or split in half if (and by) both energy sources (the terminals for the PV input and starter battery input on the DCC30S) are both energized. And the fact that the PV source comes from my "pedaling a bicycle to produce current" (or your shore charger) and the starter battery input from my "ferret in his exercise wheel" is technically agnostic to the the DCC30/50S.

And yes: amperage is delivered when demanded, provided its present and capable of traveling along the infrastructure (gauge of wires or electronic circuitry of the DCC3050S) of that it travels through.

I can't imagine any advantage to a appliance that demands, say 3, or 10, or 15, or 20 amps, but happens to be connected to a 20 amp circuit, if you catch my inference. As long as nothing bad might happen to the Gopower unit you reference in delivering less than its rated amps: something I suspect it must (be able to) do in the end (of 3) stages of its battery charging, then no harm is likely to occur either.

Noted: the Gopower is a 3 stage charger. Nonetheless I suspect the end stages of charging a battery must curtail power, suggesting the product limits the current in provides at different stages of charge of the battery it charges.

As for the price savings between the Gopower 50 and 35 amp unit, I'd be curious to know if that is also realized in utility bill savings: even is so, likely not much I'd guess.

"And the Gopower has the ability to deliver a fixed output voltage adjustable 13Vdc to 16.5Vdc. So that makes it a dumb charger and to my thinking a good stand in for an alternator."

If you hook the Gopower up to the PV inputs of the DCC30S, when the house battery is fully charged, the power the Gopower provides should be converted by the DCC30S into trickle charging power for the starter battery. See Solar Power Input on page 16 of the manual for the conditions and current levels at which this happens.

If you hook the Gopower up to terminals on your starter battery, the house battery will get charged only if (it needs to be charged and) the voltage on the starter battery exceeds the thresholds under Alternator Input at the top of page 16 of the manual. Notice that these thresholds are more easily achieved if you run an additional line from the starter battery to the IGN terminals on the DCC30S to make the DCC30S think that you are running a smart alternator--even though you likely don't have one under your hood.

In the case of hooking the Gopower up to the PV inputs of the DCC30S, house and starter battery get charged by the DCC30S' rules, not the Gopower's rules. In the case of hooking the Gopower up to the terminals on your starter battery, we can expect the Gopower's rules to be followed for the starter battery, but charging the house battery will likely be by the DCC30S' rules.

"There is still some trepidation about using the PV+ for the converter. I don't know if there is different circuitry behind that input."

I think the input to the PV terminals of the DCC30/50s is "technically agnostic." As long as your not exceeding any current limits, and providing DC input in the "12V range" (which is usually up to what, 20 volts? for a solar panel) the DCC30S shouldn't care what (relatively clean) power source is energizing those terminals. Personally, and provided it's safe, I'd prefer in your case for the Gopower to input itself into the PV terminals of the DCC30S--more on that below.

"There must be some difference in the circuits from the PV to the ALT if PV trickle charges the chassis battery."

Yes. Plugging your Gopower into the PV terminals of the DCC30S will cause the alt terminals ofthe DCC30S to output only trickle charge levels. While plugging your Gopower on the starter battery terminals will allow up to 30 amps of power to charge the house battery, if the house battery needs charge, and provided the DCC30S meets the criterion on the top of page 16 of the manual for starter battery voltage. If these conditions aren't met the house battery gets nothing.

It seems to me that hooking your shore power up to the PV terminals of the DCC30S is the best way to go, much as I suggest that you check with Renogy first. Your starter battery should not need more than the trickle charging the DCC30S will provide it after the house battery is charged, provided your starter battery and alternator are in good working order, and you don't tax the starter battery without the engine on, but for engine cranks.

" I'm just trying to think this through and asking a lot of questions to anyone who might have insight to offer. I'm curious to know if you think I'm actually better off with the 35A model. And what you think of my plan to use some sort of transfer switch to disconnect the alternator when I go to shore power."

If you stick with the DCC30S and have no foreseeable greater current usage for the Gopower beyond this discussed scenario then why spend more for the 50amp version? As for your use of a transfer switch to disconnect the alternator when you go to shore power, that idea "loses me" a bit.

Here's what I see happening: If you hook your Gopower up to the starter battery, and you pull into your driveway, I suspect you are going to turn the engine off first. Thereafter you plug in your shore power to energize the Gopower. Why are you worried about your alternator? Worse case you forget to unplug the shore line when you start your engine in anticipation of travel. What bad may happen--pulling the shore line you forget to disconnect notwithstanding--electrically speaking.

And if you hook your Gopower up to the PV terminals on the DCC30S, you are at most trickle charging your starter battery. There's nothing wrong with that (its just superfluous) with the engine on. And with the engine on the starter battery isn't going to charge the house battery unless all the conditions on the top of page of page 16 of the manual are met, AND, the house battery needs the charge.

Suppose you just pulled in your vehicle into your driveway and somehow your house battery is need of charge, and the engine is on, AND shore power is connected....

that is the same as running your vehicle on a sunny day with a solar panel. Two energy sources charge the house, then starter battery, all coordinated by the DCC30S just as designed.

 

[stinky]

You seem very clear on the specs of these Renogy devices. That's great because trying to get info out of Renogy is a waste of time.

So the DCC30S will pull the entire 30A from one source or the other in the absence of 2 sources to split the load between. That makes sense and is a question out of the way.

It's starting to make sense to use the PV terminal for the charger so that the starter battery will be trickled when I'm parked with shore power. And then of course that leaves the Alt terminal free for the alternator. But some sweet day I will want to use solar and this question is going to come up again. What would you think at that point? Charger and panels both to the PV terminal?

You keep going back to the charger stages. It's quite clear now that I can use the Gopower in fixed voltage mode continuously. My battery mfg stipulates 14.6V but I'm thinking maybe I should just set the charger to say 14V and let the Renogy boost from there. Make sense to you? Anyway, there are no charging stages in my plan. Also no intention of connecting the Gopower to the starter battery.

So thanks a lot. You've really helped me through this ordeal. I'll sleep on it for a week or so and if nothing comes along to change the calculations I'll get the 55A model and run it though the PV terminal.

 

[mkaye]

the DCC30S is a fairly simple device if you look at each input separately
anything can be connected to the PV input, as long as it meets the voltage/current requirements
this input is routed to the house battery if it needs charging using the selected charge profile
otherwise it goes to the alternator input (if the voltage is <13.2V indicating the engine is off - assuming not a smart alternator & using the IGN sense wire) and this is a fixed LA profile that we don't have access to
when you start your engine the alternator voltage is now >13.2V and it routes current from here to charge the house battery if required, it also stops any charging of the engine battery