48 volt battery charging

[SunEagle]

I found this cc on ebay at what seems a reasonable price compared to other. Do you think this is a decent cc for my application. I am getting a 4th panel to add to the set up that will be mounted on a pole in the yard.

Intronics MPPT75HV 75Amp 12/24/36/48V MPPT Solar Panel Battery Charge Controller

Chances are that it is really a PWM type. Unfortunately most of those low cost MPPT type chargers are not what they claim. Most people that purchased them found out the hard way after receiving it that they did not get what they wanted.

The least expensive MPPT charger I have seen is made by Tracer. It is an MPPT charger but does not have a lot of programming abilities a quality MPPT charger has as well as what you really want in the long run.

My advise it to not cheap out on an MPPT type charger. Get a quality one made by a well known manufacturer.

[Nazproperties]

charge wire

Ok, so this project is past budget, so lets do it right. Next question is about the wire gauge from the cc to the 48 volt battery bank. I have read at least 10 gauge. If I was to sacrifice at set of jumper cable (for the clips) most are 4 gauge, is that over kill? What is your opinion/advice. 20 ft would definitely be enough distance, probable could get by with 12-15 ft.

[SunEagle]

Ok, so this project is past budget, so lets do it right. Next question is about the wire gauge from the cc to the 48 volt battery bank. I have read at least 10 gauge. If I was to sacrifice at set of jumper cable (for the clips) most are 4 gauge, is that over kill? What is your opinion/advice. 20 ft would definitely be enough distance, probable could get by with 12-15 ft.

The wire size between the CC and battery will be based on the maximum current the CC can deliver. A #10 awg wire can accept about 30 amps, so if you have a 45 amp CC you would need about a #8 awg wire. You also don't want to exceed a 2% voltage drop so depending on long the wire is you may have to increase the size.

[inetdog]

... If I was to sacrifice at set of jumper cable (for the clips)....

I hope that this does not mean that you are thinking of using battery cable clamps to attach your wires to the battery posts. That is a very bad idea, both because it is hard to maintain low resistance and because of safety issues of one of the clamps comes off.

[SunEagle]

Cable Termination

Nazproperties

I am not sure if your CC can accept those #4 awg jumper cables due to their large size.

Whatever cable you use please make sure they can be properly terminated at the CC and battery terminals using cable lugs or compression fittings. Lose connections will overheat and can cause a fire.

[Sunking]

You do not have enough panels for a 48 volt system. You only have 3 100 watt 12 volt battery panels. All you can do is either 12, 24, or 36 volt battery.

[Nazproperties]

battery cables

I do know not to use clips if you are not watching it, as in jumping car batteries. I'm after the heavy 2 Conductor wire. Found 16ft, 6 gauge and will sacrifice the clips for the wire. What are compression fittings? I was planning on using lugs. Thank you for all your advice and insight.

[Mike90250]

What are compression fittings? I was planning on using lugs

Compression fittings aka terminal lugs, are generally thickwall copper lugs that require a hydraulic crimper, or 36" long pliers, to compress them properly to code. Cost starts about $1 ea for #4 AWG size, and increases as they get larger. Most code compliant ones have sealed ends and brazed barrels. Good ones do not have a setscrew to attache the wire.
Copper-Lugs-1Hole-Standard-query3.jpg





Ring terminals come in $4 "terminal kits" with 180 assorted terminals, and are mostly for low current (<10A), automotive wiring. Many pliers have notches to crimp them with.

[Nazproperties]

Fuse type

You do not have enough panels for a 48 volt system. You only have 3 100 watt 12 volt battery panels. All you can do is either 12, 24, or 36 volt battery.

I have up graded to 4 100 watt panels with a total of 30 amps. What is the best type of fuse and housing/holder to use between the 48 volt batteries bank and the CC?

[Mike90250]

I have up graded to 4 100 watt panels with a total of 30 amps. What is the best type of fuse and housing/holder to use between the 48 volt batteries bank and the CC?

i would use a circuit breaker. Midnight Solar has some fair priced ones. When you want to power things off, you can't "just pull a fuse" on DC, all you do is make an arc welder, and you have your fingers right there.

The Circuit Protection Device should be sized to protect the wires from melting.

Most modern charge controllers have internal protection fuses, you don't need another one.

[Nazproperties]

Off grid batteries

Got the 48 volt set up and working, have decided to have an additional 12 volt recharging and inverter for A/C power. Old 12 volt deep cycle batteries I have won't hold a charge long, so investing in new batteries. Would like to have at least 100 AH. Would like to hear from you'll about best batteries brands and other suggestions.

[Mike90250]

... Would like to have at least 100 AH. Would like to hear from you'll about best batteries brands and other suggestions.

What is your goal ? What size is the array - so you don't over battery it, and have sulfated batteries?

Are you confident enough in your calculations, to sink major $$ into a battery bank, or do you want to consider a training bank of 200Ah, 6V golf cart batteries ?

[Nazproperties]

What is your goal ? What size is the array - so you don't over battery it, and have sulfated batteries?

Are you confident enough in your calculations, to sink major $$ into a battery bank, or do you want to consider a training bank of 200Ah, 6V golf cart batteries ?

Need to be able to run refrigerator, few other household item when power is down. Back up to the back up you might say. I have a 48 volt golf cart with 8 volt batteries X 6, and 48 volt inverter but GC is strictly electric vehicle transportation in my local area. What brand to you recommend for 12v 100Ah. Battery type AGM/Gel? Want long term batteries for 12 volt inverter that's 2500 watts.

[Mike90250]

...... What brand to you recommend for 12v 100Ah. Battery type AGM/Gel? Want long term batteries for 12 volt inverter that's 2500 watts.

Brands depend on what you can get in your area. If you can come up with a solar or off grid chargeing scheme for your golfcart, that would be great.
AGM batteries do not last as long as cared for flooded. Avoid Gel.
For cheap standby use, use the 6V golf cart batteries.

[Sunking]

What brand to you recommend for 12v 100Ah. Battery type AGM/Gel? Want long term batteries for 12 volt inverter that's 2500 watts.

The largest inverter you can run on a 12 volt 100 AH AGM battery is 300 watts. At 2500 watts is a job for a 48 volt 200 AH AGM battery which is even a bit larger than your golf cart batteries Any inverter 1000 watts or larger on 12 volts is asking for a nice little electrical fire.