Can a solar charge controller be wired in through audio power amplifier wiring?

[Haspin FJ]

Wondering if the power from a solar panel charge controller can be tied in directly to existing heavy gauge wiring going to my powered subwoofer in the back passenger quarter panel instead of having to run more wires all the way back to the battery? Seems like it would be basically doing the same thing except when the amp is powered on and then would he trying to pull some of that power back the opposite direction of the battery. Seems to me like it would work since it's really all connecting the same positive and negative source but also thinking I may be missing something important and don't want to fry anything. TiA.

 

[e9999]

A bit unclear but if you are talking only about DC "12V" power wires between a battery and the subwoofer, that should likely be fine, at least powerwise, I think. Whether you connect the controller directly to the battery physical posts or to the power input on the other side of wiring out of the battery doesn't make much difference aside from small voltage drops one way or the other. Of course, you'd want to make sure the wires are big enough to handle the controller current, and that the subwoofer can handle whatever voltage comes out of the controller. I'm assuming that you are talking about an MPPT controller, I would be wary of using a PWM one because of noise. But then again, an MPPT one could also create noise. I'm assuming that the audio wires will not be involved. So, yea, that sounds OK to me (but been wrong plenty before).
But if you are talking about wires from the amplifier to the subwoofer instead, with no battery directly involved, that is a whole different ball of wax.

 

[peesalot]

The only thing I can think of is that the controller will see a temp low voltage when the sub hits so the controller will see rapid up & down volt readings whereas if it was on a separate cable to batt the batt would act as sort of a surge tank and possibly reduce or make the volt fluctuations a non issue, thats an e9999 ?

 

[e9999]

^ that would only be an issue if the wires are not big enough, I think. Otherwise, there would only be small voltage drops. But as to whether rapid fluctuations in voltage might confuse the controller, well, that is hard to predict. But possible, I guess. I would think a reputable brand controller would not blink. And you could also have the controller read the battery voltage remotely instead if it allows that.

Having said all that, I would personally rather have wiring directly from the controller to the battery. For one thing, it likely does not have to be big wires if you don't have giant panels, and seems like a cleaner approach overall, with appropriate fusing, good voltage control etc.

 

[Haspin FJ]

A bit unclear but if you are talking only about DC "12V" power wires between a battery and the subwoofer, that should likely be fine, at least powerwise, I think. Whether you connect the controller directly to the battery physical posts or to the power input on the other side of wiring out of the battery doesn't make much difference aside from small voltage drops one way or the other. Of course, you'd want to make sure the wires are big enough to handle the controller current, and that the subwoofer can handle whatever voltage comes out of the controller. I'm assuming that you are talking about an MPPT controller, I would be wary of using a PWM one because of noise. But then again, an MPPT one could also create noise. I'm assuming that the audio wires will not be involved. So, yea, that sounds OK to me (but been wrong plenty before).
But if you are talking about wires from the amplifier to the subwoofer instead, with no battery directly involved, that is a whole different ball of wax.

Thanks. That was my thinking as well but wanted to get some external input, lol. Yes, I'm just talking about the thick +/- wires coming from the battery to the amplifier. I'll probably install a small fuse block just before the amp to tie both into and fuse the two sources independently based on their ratings as well as have the main fuse by the battery for the big positive wire and confirm its heavy enough.

 

[Haspin FJ]

The only thing I can think of is that the controller will see a temp low voltage when the sub hits so the controller will see rapid up & down volt readings whereas if it was on a separate cable to batt the batt would act as sort of a surge tank and possibly reduce or make the volt fluctuations a non issue, thats an e9999 ?

Good point. May take some trial and error I guess for that.

 

[e9999]

are you talking about a battery in the cabin or in the engine bay? If it's the starting battery in the engine bay, it might be good to make sure the controller knows the temperature of the battery for proper compensation.

 

[ntsqd]

If the amp is big enough, and there isn't a power cap on the circuit, then a big hit could drop the line voltage and confuse the solar controller. If you're not listening to EDM or death metal then it may not matter.

OTOH, voltage drop when charging batteries is something to avoid at all costs. Doesn't take much drop to slow the charge rate down to near zero. Which is part of the reason why the controller usually wants to be very close to the battery.

 

[Haspin FJ]

are you talking about a battery in the cabin or in the engine bay? If it's the starting battery in the engine bay, it might be good to make sure the controller knows the temperature of the battery for proper compensation.

If the amp is big enough, and there isn't a power cap on the circuit, then a big hit could drop the line voltage and confuse the solar controller. If you're not listening to EDM or death metal then it may not matter.

OTOH, voltage drop when charging batteries is something to avoid at all costs. Doesn't take much drop to slow the charge rate down to near zero. Which is part of the reason why the controller usually wants to be very close to the battery.

It's a Cerwin Vega sub with a built in amp, nothing crazy, probably 100w, and I barely turn thing up much these days as well as my current stero being volume limited with some issue it has. Regardless I'd want to keep it right. In all honesty installing it is more to have the rig solar ready and possibly maintain the starting battery when the rig sits but the panel will switch over to mostly keep a Bluetti power station charged when traveling and want a way to keep the solar panel hooked up at all times so it doesn't get fried or have to be covered or removed between usage. Only using 100w renogy panel and charge controller for now and only an AMG x power battery as far as the battery charging concerns.

 

[peesalot]

e9999 - my solar controller is simple 8 amp ( 125W ) cheapo with no special attributes. Seems to keep batts up fine with sun. After reading your comment regarding the controller knowing batt temp I am curious if a better solar charge controller with systems to monitor things like batt temp would produce a better charge or be better for the batt ? I dont see spending the coin for those controllers unless there is a benefit ?

 

[ntsqd]

When the solar controller can be in close proximity to the battery there is charging some temperature compensation that occurs naturally.

The more sophisticated controllers probably do a better job of using all of the available power to charge the battery. One you're into multi-stage MPPT charging my thinking is that going much beyond that is a steep slope in ROI. Only a little better costs a LOT more. If a simple PWM multi-stage charger is getting the job done and not damaging the battery(ies) I'd be reluctant to change it.

On the CTD/pop-top camper I use the starting battery to camper battery 6ga. cables to power the OBA compressor. I am NOT using a DC-DC charger, just a VSR between the batteries. The camper's solar charges the camper batteries first. When they reach a high enough voltage the VSR closes and the solar charges both sets of batteries. All of that will likely need to change when I move to a LiFePO4 camper battery, but I haven't decided how. I'm resistant to a DC-DC charger because AFAIK they only charge in one direction and I want to charge in either direction depending on the source of charge (Solar, alternator, 120VAC charger).

 

[e9999]

I would think that active temperature compensation is a good thing. How much? I don't really know for typical situations. However, for an engine bay battery it could be more important if the temperature gets up there. You probably don't want to overheat the battery. But all that just a WAG, though.
Voltage compensation (meaning the actual battery voltage is used in the algorithm, not that of where the controller is located) is a bigger deal IMO as it can help speed up charging if your wires are marginal or long. I try to get that working whenever I can.
All that worth the cost? Sorta a minor issue for me because my Victron controllers all already have built-in provisions for remote temperature and voltage compensation, but of course those controllers are typically more expensive than most to start with. And you do need some wiring and/or sensor or a bluetooth remote battery sensing device, though, so yes it adds up a bit. YMMV.
Overall, probably not really worth worrying about too much for the smallish systems we are talking about usually for trucks, unless you have an odd situation, like maybe very high temps or too thin wiring.
It's like all the efficiency considerations (including MPPT vs PWM), yes, important when you are short of power or space, but use a bit bigger panels and you don't have to worry about efficiency any more. It's basically cheap PWM controller and bigger (costlier) panels vs more expensive MPPT and smaller cheaper panels, your choice. Me, I would not buy/use a PWM controller any more, no point IMO, the MPPTs are typically better overall.

OP, not having the panels connected doesn't hurt them significantly AFAIK - I imagine they could get a bit warmer but that is not likely a big deal. As to using a Renogy controller: not for me, I don't have much trust in the brand. Not too long ago, I bought one to test out and see how it compares to my Victrons. Ironically enough, though, I could not even check it out because it arrived defective, and customer service was aggravating and useless. Not too big a deal, of course, but I have also read of serious controller failures with damage downstream.

 

[Haspin FJ]

I would think that active temperature compensation is a good thing. How much? I don't really know for typical situations. However, for an engine bay battery it could be more important if the temperature gets up there. You probably don't want to overheat the battery. But all that just a WAG, though.
Voltage compensation (meaning the actual battery voltage is used in the algorithm, not that of where the controller is located) is a bigger deal IMO as it can help speed up charging if your wires are marginal or long. I try to get that working whenever I can.
All that worth the cost? Sorta a minor issue for me because my Victron controllers all already have built-in provisions for remote temperature and voltage compensation, but of course those controllers are typically more expensive than most to start with. And you do need some wiring and/or sensor or a bluetooth remote battery sensing device, though, so yes it adds up a bit. YMMV.
Overall, probably not really worth worrying about too much for the smallish systems we are talking about usually for trucks, unless you have an odd situation, like maybe very high temps or too thin wiring.
It's like all the efficiency considerations (including MPPT vs PWM), yes, important when you are short of power or space, but use a bit bigger panels and you don't have to worry about efficiency any more. It's basically cheap PWM controller and bigger (costlier) panels vs more expensive MPPT and smaller cheaper panels, your choice. Me, I would not buy/use a PWM controller any more, no point IMO, the MPPTs are typically better overall.

OP, not having the panels connected doesn't hurt them significantly AFAIK - I imagine they could get a bit warmer but that is not likely a big deal. As to using a Renogy controller: not for me, I don't have much trust in the brand. Not too long ago, I bought one to test out and see how it compares to my Victrons. Ironically enough, though, I could not even check it out because it arrived defective, and customer service was aggravating and useless. Not too big a deal, of course, but I have also read of serious controller failures with damage downstream.

Got ya. I'm not particular to Renogy, just what I had available from another project so figured I'd make use of it, and theoretically better then some of the No Name total garbage low end "Amazon" stuff out there, although I'm sure some of them are probably comparable. Thanks for all the input.