EPEver AN Tracer with a boost convertor

[DarrenH]

Bit of an odd question and could be a very stupid one, but I wanted to see.

I have a small 50w 12v panel, a EPEver Tracer AN Controller, and a 100Ah 12V AGM Battery.

The problem is that the 50w panel rarely gives me enough voltage to get the EPEver into a reasonable charging range. For example on a very sunny day, I have nothing more than 2w. But I have learnt that it wont start to charge at a good rate unless the voltage at a certain level. So playing around I installed a suitably rated boost convertor between the panel and the EPEever controller, and I was getting 20w even late in the day and it was finally putting some voltage back into the battery.

This was just a test and I have reverted back to how it should be, and I know the obvious option here is to get another 50w panel in series, but in the short term, can anyone tell me if doing what I did would be a problem? Heat dissipation and maybe inefficient might points raised, but its in a cold area, so heat wont be an issue, and as for efficiency, surely this is better than how it was?

Thanks

 

[BlueFox]

MPPT won't work through the boost converter, but as you've found you'll still get something out of it at least.

 

[DJSmiley]

Get a cheap PWM controller. MPPT doesn't have much benefits if your panel voltage isn't very much more than the battery voltage.

Benefits of a MPPT is with multiple panels in series, or panels with higher voltages. The MPPT will start also on lower light situations with some charge, and there is less loss of cables and voltage drop.

Due to the switching in the MPPT, it requires generally Vbatt + 4 or 5V, where as a PWM doesn't require this difference (it even can't use that additional voltage efficient - thats why you need a switching (MPPT) for maximum efficiency if the panel voltage is > battery voltage)

15V panel with PWM on a 12V battery -> Works fine
50V panel with PWM on a 12V battery -> Highly inefficient
50V panel with MPPT on a 12V battery -> Works very efficient, also added benefits are it will start charging even in lower light situations

 

[DarrenH]

Get a cheap PWM controller. MPPT doesn't have much benefits if your panel voltage isn't very much more than the battery voltage.

Benefits of a MPPT is with multiple panels in series, or panels with higher voltages. The MPPT will start also on lower light situations with some charge, and there is less loss of cables and voltage drop.

Due to the switching in the MPPT, it requires generally Vbatt + 4 or 5V, where as a PWM doesn't require this difference (it even can't use that additional voltage efficient - thats why you need a switching (MPPT) for maximum efficiency if the panel voltage is > battery voltage)

15V panel with PWM on a 12V battery -> Works fine
50V panel with PWM on a 12V battery -> Highly inefficient
50V panel with MPPT on a 12V battery -> Works very efficient, also added benefits are it will start charging even in lower light situations

OK, understood. Thanks for the explaination.

I did have a MPT-7210A charging a home made small 18650 bank I made, but as I came across 4x 101aH 12v Batteries from work for free I wanted to upgrade, and the MPT-7210A didnt look like it was capable of charging AGMs.

I think I will just buy 2x 100w Panels and run all 3 (2x 100w plus my current 50w) in series and that should provide the needed voltage.

Thanks again.

MPPT won't work through the boost converter, but as you've found you'll still get something out of it at least.

I was surprised it did, in fact it worked really well and was charging the batteries for the first time properly. Before the voltage was dropping just with some LED lights on the load. I guess it was more to check about the long term effects of this. But I guess as described my setup isnt really the intended use for MPPT.

Thanks both.