12v car alternator charge 24v battery bank into mppt controller w/panel v boost

[alpinebound]

hi im new to the solar scene i have hooked up 8, 245w 52 voc panels in parlell to a 80v max in mppt charge controller i have 8 6v 220 ah golf cart batteries (it doesnt say at what amp the amp hour drain is at) wired in 24v with two strings this bank i sort of stabbed in the dark with and is way under powered.
Q i was trying to use the bank as a buffer as i have a grease car i was trying to use as a generator to top off with beig a 24v system and a 12 v altenator i was wondering if i could tap into the in on the charge controller side to boost the incoming voltage 52 panels +15 on the car. toget 67 ish as i understand i will still get some high voltage on cloudy days but supplement some amps from the car as the panels will drop off right?
Q can i put a diode in line to protect my car from high voltage when connecting to the panels ,will the cars 60 amp current hurt the panels , will the current leak into the panels as it would be cloudy , will my voltage regulator on the alternator be stressed ?will this scheme not likely work? thanks

[thastinger]

I'm no expert but I don't know of a CC that could combine the 2 power sources to charge the battery bank...which I assume is 48V in one string, not 24 as you stated.

[inetdog]

I'm no expert but I don't know of a CC that could combine the 2 power sources to charge the battery bank...which I assume is 48V in one string, not 24 as you stated.

Read the OP again. Eight 6 V batteries in two parallel strings of four.
And, yes, trying to put two unrelated voltage and current sources in series will not work. Or at least not well enough to justify trying it.

[alpinebound]

Read the OP again. Eight 6 V batteries in two parallel strings of four.
And, yes, trying to put two unrelated voltage and current sources in series will not work. Or at least not well enough to justify trying it.

thanks for the reply, yea i ment the two string of four 6v batteries for a 24v batterry bank. we got cheap 220 ah batteries so i only have 440 ah total

my charge controller says it get handle 80v in max so my panals 52 voc + 15 from the car is under the limit
i was thinking of having a plug in paralelell and combine the panels and car coming into the charge controller

[inetdog]

thanks for the reply, yea i ment the two string of four 6v batteries for a 24v batterry bank. we got cheap 220 ah batteries so i only have 440 ah total

my charge controller says it get handle 80v in max so my panals 52 voc + 15 from the car is under the limit
i was thinking of having a plug in paralelell and combine the panels and car coming into the charge controller

How are you getting the figure of "15 from the car". I would guess that you are not putting 15 panels on the car, you are getting 15 amps from the car alternator. But the car alternator will deliver only 12-14 volts so you cannot put it in parallel with the 52 volt (Vmp ~40 volt) panels and expect anything useful to happen.
Similarly, if you put the two in series all of the 56 amps from your panels will be going through the alternator. Also not good.

If your CC had two separate MPPT inputs, it still would not be good because your alternator is a voltage source not a current source and the MPPT CC would try its hardest to kill your alternator.

You are missing some very basic knowledge of electricity and trying to teach you that by remote control is not a winning proposition. Please find somewhere local to learn basic electronics, then come back for advice.

Sincere Best Wishes,

'dog

[alpinebound]

How are you getting the figure of "15 from the car". I would guess that you are not putting 15 panels on the car, you are getting 15 amps from the car alternator. But the car alternator will deliver only 12-14 volts so you cannot put it in parallel with the 52 volt (Vmp ~40 volt) panels and expect anything useful to happen.
Similarly, if you put the two in series all of the 56 amps from your panels will be going through the alternator. Also not good.

If your CC had two separate MPPT inputs, it still would not be good because your alternator is a voltage source not a current source and the MPPT CC would try its hardest to kill your alternator.

You are missing some very basic knowledge of electricity and trying to teach you that by remote control is not a winning proposition. Please find somewhere local to learn basic electronics, then come back for advice.

Sincere Best Wishes,

'dog

the voltage regulator on my 300sd is putting out 15v it is rated at 67 amps when my cc is in bulk mode it will convert the high v dc to 24-27v dc and almost double the amps from the panels to the batteries im trying to find out if i can also use my car to connect in paralell with the panals to the cc
what im trying to do may be possible but it might stress the voltage regulator
i have hooked up my stand alone system with no assistance besides the internet and we are totally offgrid during sunlight hours voltage regulators are replacable and cheap on this car

what ive learned about electricity is you hook it up and it works or theres smoke and sparks

[thastinger]

I think you'll find that your van alt puts out closer to 17-18V and can be a ton of amps, 55-100 depending on model.

[inetdog]

I think you'll find that your van alt puts out closer to 17-18V and can be a ton of amps, 55-100 depending on model.

But it also puts out three phase rectified (pulsed) DC and without being attached directly to a battery for filtering, that waveform will drive the MPPT controller nuts.
Not worth the effort. If the alternator delivered 24 volts rather than 12 volts I would recommend connecting it directly to your battery bank in parallel with the solar CC, with isolation diodes.

[Sunny Solar]

17 or 18v (which I very much doubt you will get under load) is never going to do anything useful connected to a 24 v battery bank. And there is no way you could successfully connect the alternator in series to the panels then to the charge controller.... And another thing you would have to be running the alternator at at least 2000 rpm to get full output. And to do that obviously you need it connected to an engine that is going to be consuming more fuel than the equivalent output.. a complete waste..

GIVE UP