48 volt battery charging

[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]

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]

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]

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]

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.

[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.

[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.

[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]

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.

[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]

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]

cc

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

[SunEagle]

I've seen those and not part of the plan. The ultimate reason for doing this is back up renewable energy supply with what I got for batteries. A full off grid solar system is already more than a few $$$$$$. Saving on total cost by using what I already got. Seemed like a good idea at the time.

I was thinking you would recharge you golf cart when you weren't using it so the panels could be set up in a fixed position. Sunking was thinking you wanted to mount the solar panels to the golf cart and try to recharge as you are driving the cart around.

The second method (charging while driving) really doesn't work well. But a fixed array of the right size will recharge the batteries when the cart is parked.

[Nazproperties]

Golf Cart batteries

I've seen those and not part of the plan. The ultimate reason for doing this is back up renewable energy supply with what I got for batteries. A full off grid solar system is already more than a few $$$$$$. Saving on total cost by using what I already got. Seemed like a good idea at the time.

[Nazproperties]

MPPT charge controller

Can you recommend a good MPPT charge controller for 48 volt?