My Ideas on solar, please give your opinion, Thanks!

[Sky King]

Have a converted diesel ambulance with a 250 amp 12v altenator,2 new starter batteries & 4 6v golf car batteries in the back, a device that works like a diode that lets the altenator charge them all but only discharge the ones in the back or push a button & use the rear ones to start it. I've done remote way off grid power systems using  a genset, batteries, Inverter, charger & only a solar panel to keep the batteries topped off when no one was there for a long time. I have a 1000 watt pure sine & a 2000 watt not pure sine invertors. Here's my question can I wire the 4 panels in series  from the trailer to charge controller in the amblance & then reduce it to be able to use smaller/longer cables? I have a wooden spool of 2 ga & one of 2/0 welding cable & would probably break the lenths to 4 25' with Anderson clips which I have. I will have a switch so the batteries charge on either the altonator or the panels & everything fused of course. Thanks in advance for any & all help!

 

[picopat]

Hi Gr8ful,

We're missing two important bits of info to help, what solar panels and charge controller do you have?

Determine your panel array max voltage by taking the Voc rating, adjusting for the coldest expected temp, and multiplying by 4. That number must be lower than the solar charger controller max rated voltage.

That will make sure you don't damage your equipment but doesn't guarantee the system is efficient or work up to full capacity.

2 or 2/0 cable from the panels to the charge controller is probably overkill for 25ft but use it if you've got it.

Patrick

Sent from my Nexus 6P using Tapatalk

 

[Sky King]

I haven't picked out or picked up the panels yet, I've ticked the ones I think I wannt but the weather has been lousy & need to get them so I haven't bought a controller yet either, I have all sizes of wire & try to go 1 size bigger than it calls for. I just wanted to know if people did it this way. If I leave the panels & drive somewhere I have plenty of amps to keep the batteries charged. I've done several systems & the batteries lasted about 12 years on the last several. Just like vehicles if you understand them & take care of them they last. They have all kinds but here's 5 at random which would you recomend? JA Solar 325W JAP72S01-325/SC $115, Yingli 325W YL-325P-35B-72 $121, Boviet 305W Poly BVM6612P-305 $103, SunPower 320W SP $106, Trina 345W Mono TSM-DE14A(II)-345W $127 Please let me know which if any you recomend & what controller, Thanks!

 

[Weight]

Most panels will be fine with 8awg to the controller. Especially if panels are series with higher volts. MPPT controller can be used for higher voltage solar system to charge 12 volt battery. Match the specs of the controller with the voltage of the panel array. Welding cable is not my first choice for vehicle wiring. But if you have it in hand use for the main battery connections and such high ampere devices as the 2000 watt inverter.
It is really not practicable to charge a house bank from the alternator, unless the house bank is very small with little discharge.

 

[Sky King]

A couple questions, why would a 250amp altenator not charge a 4 battery bank. I used to do 6 battery banks with a 65 or 85amp charger for 20-30 minutes a day & why not welding cable" it has the heaviest cover, is very flexable & made to be drug around for years. I thought it was the best made, please let me know as I need to know, Thanks! Eric

 

[highdesertranger]

first off with a lot of welding cable the insulation is not UV or oil/gas resistant. so it is not the best choice for mobile applications. I have seen the insulation get ruined a relative short amount of time from petroleum.

second you will not recharge a deeply discharged battery fast. it takes many, many hours of driving at highway speed to recharge no matter how many amps the alternator is. think 6, 7+ hours of driving. note idling won't cut it. for sure hook your alternator into the charge plan but don't rely on it.

another point you don't need a switch to choose between one charge source and another they play well together. however you need some kind of isolation switch/solenoid in the system. this is to prevent the discharge of the starting batteries.

highdesertranger

 

[Sky King]

Thanks for the reply. As I mentioned I have an isolation switch & never run a deep cycle to a very low level as it ruins the batteries. In my opening post 1 got 12 years of of 6 6v golf car batteries & in fact they were still doing well but my son didn't shut the inverter off & it went many months left on. No offense but you may wish to read this about welding cable http://blog.delcity.net/whats-the-difference-between-battery-cable-and-welding-cable

My question was is it a good idea to run the 4 panels in series from the remote trailer to the van so I can use smaller cable as the higher the voltage the smaller cable needed, then at the van step it down to 12 volt. Sorry if I didn't make my self clear. Thanks for the help!

 

[jimindenver]

I go the opposite route. I have a 435 watt panel on my truck and connect it to the charge controller in the trailer with 25 feet of 8 gauge MC4 cable under the trailer, then two extensions at the tongue. One is 10 feet to hook up the panel while I am on the road, the other is 50 foot of cables so that I can move the truck around while the trailer is parked. Both extensions are 10 gauge MC4 cables connected with 50 amp Anderson connectors.

The panel is 435 watts with a 79 Voc. The controller is a Morningstar TS-MPPT-45 which is set the same as the trailers TS-MPPT-60 that runs the 750 watts on the trailers roof. Tracking the sun the truck's panel puts out 29-32 amps to the bank.

 

[Weight]

what HDR said. Thanks.

 

[Sky King]

OK I asked him to explain & he hasn't so please explain the questions I asked under his post. I've done this as explained many times in remote camps & never had a glitch. I was just asking about having the panels away from the van & wiring the panels in series so the higher voltage needs smaller wire to get to the van. So please explain. Thanks!

 

[Weight]

If you run the panels in series you will have higher voltage and less voltage drop to the controller, a good thing. But you must use a MPPT charge controller. What most do is cheap out on the controller as MPPT are more money, brand for brand, than PWM. I went the other way and wired panels in parallel with a 45 amp Morning Star PWM controller. I have experienced no problems with 690 amp hours and 400 watts of panels. The wiring does get a bit more complicated, but not that bad.

 

[Sky King]

Yes I plan on the better controller, I'll have 1300 watts of panels & not sure of how many batteries yet, Thanks!

 

[Sky King]

first off with a lot of welding cable the insulation is not UV or oil/gas resistant.  so it is not the best choice for mobile applications.  I have seen the insulation get ruined a relative short amount of time from petroleum.

second you will not recharge a deeply discharged battery fast.  it takes many,  many hours of driving at highway speed to recharge no matter how many amps the alternator is.  think 6, 7+ hours of driving.  note idling won't cut it.  for sure hook your alternator into the charge plan but don't rely on it.

another point you don't need a switch to choose between one charge source and another they play well together.  however you need some kind of isolation switch/solenoid in the system.  this is to prevent the discharge of the starting batteries.

highdesertranger

You told me to reread this post so I am. You say welding cable is not as good as battery cable. 1st it won't go near fuels as if you read it again I want the panels in the sun, & want to van in the shade. I posted this but maybe you didn't open it as it says welding cable is top notch  http://blog.delcity.net/whats-the-differ...ding-cable I won't need it this heavy as I found my answer on another site, it will be in series. I also said in my original post that I had a isolation swith but couldn't think of the name & called it a diode like swith to keep the engine batteries always charged. Thanks!

 

[highdesertranger]

you still can't read it right. I said "with a lot of welding cable", that is not the same as saying "all welding cable".

jeez I said it because I have seen it. on my welder the cable is UV degraded. I have also seen it swell up from diesel. now you can post all the links you want but I will still say some welding cable is not UV or oil and gas resistant, because I have seen it, is that so hard to understand. stop and read what is posted not what you perceive is posted. highdesertranger

 

[Weight]

The difference; Welding cable insulation is not standardized, you could have some like I had, the insulation split lengthwise. I had to wrap areas with electrical tape.
Marine cable insulation meets standards and is dependable from any supplier.
But if you have the welding cable, go ahead and use it. More important is the quality of the crimps on the end terminals. And no, soldering is not recommended and mostly frowned upon in vehicles. Boats, Planes, Trains, and RVs.