diy solar

diy solar

Using a MPPT as a battery charger?

Sorry to go slightly off topic... but I feel this is fairly related to the discussion at hand.

I am wondering if I can use an MPPT to charge a 24v system with an inexpensive 36~42V 1500W (or up to 1500W) power supply. The intention is to get a faster charge than I can get with something like the AIMS AC/DC charger, and a lower overall component cost while maintaining the ability to charge via solar or shore power as needed.
 
FlyingAvocado said:
Sorry to go slightly off topic... but I feel this is fairly related to the discussion at hand.

I am wondering if I can use an MPPT to charge a 24v system with an inexpensive 36~42V 1500W (or up to 1500W) power supply. The intention is to get a faster charge than I can get with something like the AIMS AC/DC charger, and a lower overall component cost while maintaining the ability to charge via solar or shore power as needed.
Click to expand...
more info. are you asking using a power supply to mppt to battery?
 
FlyingAvocado said:
Sorry to go slightly off topic... but I feel this is fairly related to the discussion at hand.

I am wondering if I can use an MPPT to charge a 24v system with an inexpensive 36~42V 1500W (or up to 1500W) power supply. The intention is to get a faster charge than I can get with something like the AIMS AC/DC charger, and a lower overall component cost while maintaining the ability to charge via solar or shore power as needed.
Click to expand...
Yes, but I would monitor it closely. An inexpensive power supply is not very trustworthy in keeping control of the voltage.
 
if it is going into an mppt then voltage doesn't matter...

and your Mppt would need to be 40 amps or less.
 
FlyingAvocado said:
Sorry to go slightly off topic... but I feel this is fairly related to the discussion at hand.

I am wondering if I can use an MPPT to charge a 24v system with an inexpensive 36~42V 1500W (or up to 1500W) power supply. The intention is to get a faster charge than I can get with something like the AIMS AC/DC charger, and a lower overall component cost while maintaining the ability to charge via solar or shore power as needed.
Click to expand...

Cheaper than? First, dissuade yourself from using a cheap 1500 watt supply at anything above 1000 to 1100 watts for an extended time. 3.65 x 8 x 40 = 1168. So assuming a 40 amp MPPT with 100% efficiency, you need 1200 watts sustained. Better plan on 1600 watt supply, you won't like how they fail when you push them too hard.
 
Why use the SCC at all?
You can charge the batteries, directly from the power supply.
 
timselectric said:
Why use the SCC at all?
You can charge the batteries, directly from the power supply.
Click to expand...
The original post was about using a cheap (likely not current limited supply) in conjunction with a solar charge controller to get higher current and lower priced charging than a standard Aims charger. Cheap power supplies are likely not as efficient as the AIMS (even if they have PFC), and would need to be pretty substantial. Basically it works out about the same price as the AIMS charger, or a good Meanwell power supply actually designed for charging. If he wanted 40 amps for 12v, that would be easy (but the AIMS or Meanwell would supply more current). There is a reason why the actually designed for charging at 24v chargers supply less than 40 amps, and that reason is so they won't trip breakers on a 15 amp 120v circuit.
 
Last edited:
GSXR1000 said:
15 amp at 120v could easily charge at 60 amps 24v
Click to expand...

8 x 3.65 x 60 = 1752

1752 ÷ 120 = 14.6 amps assuming 100% efficiency.

Yes, most modern circuits can easily handle 1800 watts, assuming my wife doesn't turn on the microwave or electric teakettle at the same time. Most power supplies and chargers are not 100% efficient.
 
GSXR1000 said:
well I decided to go with it.... I like the bulk/ float function so I can store the battery at a lower voltage.. 5 minutes in and working great View attachment 102052View attachment 102053
Click to expand...

Well, I can tell you that I've tested an 800 watt supply hooked up to a 40 amp MPPT to charge a 12v system. But that is under 600 watt load, if I had tried a 24v system it would have burned out the power supply.
 
The solar panels have source resistance. Higher than the cable resistance.
While the batteries have almost none. I would dirty it up with some power resistors.
The fellow on the DIY link used an old projector bulb.

I did not try it with my old EPEVER MPPT controller since it was positive ground. Regulates between the negative terminals. The wiring would have shorted the negatives and smoked. Many controllers are built like this to use the robust and cheaper NMOS FETS vs. PMOS FETS.
 
Last edited:
mikefitz said:
No, Victron do not recomend using a battery as an input source to the MPPT, it will cause damage, use DC to DC 24 to 12 charger. Victron Orion 24 12 20,

Orion-Tr Smart DC-DC Charger Isolated - Victron Energy

The Orion-Tr Smart DC-DC charger is a professional DC to DC adaptive 3-stage charger with built-in Bluetooth. For use in dual battery systems in...
www.victronenergy.com www.victronenergy.com

It's possible to use a current limited power supply but not a battery.

Mike
Click to expand...
what if a PWM solar chager contoller was used?
 
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