Renogy Wanderer 10a not charging Lifepo4 properly. Alternatives?

[Novatek]

Hi, I'm new to solar and recently bought a Renogy Wanderer 10a solar charge controller to charge a 12ah 12v lifepo4 battery with a 25 watt 12v solar panel. I have the Bluetooth module installed so I could easily set the controller settings. I have it set to lithium and to charge at 14.4v as directed by the battery instructions. The problem is, even in full direct sunlight it never charges at the 14.4v I set it too. Usually it's in the 13.5v range and as a consequence it doesn't fully charge the battery. I have seen other people comment they had similar problems with this charge controller. I looked on Amazon for alternatives and most have comments saying they won't charge at the correct voltage for lithium batteries even if the controller supports it.

Can anyone suggest a reasonable alternative that actually charges lifepo4 at 14.4v?

Thanks so much in advance.

 

[rodrick]

Are you sure the 25 watt panel is producing a high enough voltage what are the panels specs?

 

[Novatek]

Are you sure the 25 watt panel is producing a high enough voltage what are the panels specs?

Eco-Worthy 25watt panel

Portable & High Efficient 25W 12V Solar Panel​

• Rated power: 25W
• Solar Cell: Monocrystalline
• Voc: 22.41V
• Vpm: 18V
• Short circuit current(Isc): 1.54A
• Maximum current: 1.4A
• Panel size: 16.5x12.6x0.67inch
• Weight: 4.54 lb
• Length of extension cable: 3.28ft(39.3 inch); 18AWG
• Temperature range: －40℃～ +85℃

 

[rodrick]

I think you may need more panels with zero load on the battery it will take 6 hours at full power from the single panel just to charge the battery if there is a load you will not get near fully charged

 

[Novatek]

I think you may need more panels with zero load on the battery it will take 6 hours at full power from the single panel just to charge the battery if there is a load you will not get near fully charged

Shouldn't the charge controller show it charging at the set voltage in full sunlight?

 

[rodrick]

Shouldn't the charge controller show it charging at the set voltage in full sunlight?

Until you get the battery near full it will pull the voltage down

 

[Novatek]

Until you get the battery near full it will pull the voltage down

Alright what would be the correct wattage panel size assuming 4hrs of direct sunlight?

Edit: this site https://dotwatts.com/solar-panel-size-calculator/ shows my panel should be very close to adequate. So I'm not sure what I need.

 

[rodrick]

Your battery is approximately 150 watts/ 4=37.5 min with no load so paralleling a second panel would work with a little extra on good days and maybe enough on low pv days

 

[Novatek]

Your battery is approximately 150 watts/ 4=37.5 min with no load so paralleling a second panel would work with a little extra on good days and maybe enough on low pv days

Thanks for your help. Would it be better to add another panel or just use one panel(50w) or does it not matter?

 

[HarryN]

My suggestion is to use a bogart SC 2030 charge controller instead.

As far as a solar panel sizing - 25 watts is for elementary school children's science class experiments. Think in terms of 10 - 20x this number.

 

[Novatek]

My suggestion is to use a bogart SC 2030 charge controller instead.

As far as a solar panel sizing - 25 watts is for elementary school children's science class experiments. Think in terms of 10 - 20x this number.

Thank you for your suggestion. I'm not powering a house, so much more than what I have is overkill.

 

[HarryN]

Thank you for your suggestion. I'm not powering a house, so much more than what I have is overkill.

Yes - well to put it into perspective, I help people with van electrical systems.

So for that application it is loads such as led lights, fan, USB cell phone charging, and often a DC refrigerator.

For a vehicle type application, what we would use a 25 watt panel for is to keep a trickle charge on the vehicle starter battery to keep it from going dead if the vehicle were not going to be used very much.

It could also be used potentially to charge a cell phone ( just barely ) or run an LED light.

To run a DC refrigerator in a van application we would put 400 watts on minimum.

_____________

For math purposes, suppose that you have a LiFe battery, nominal 12 volts, 100 amp -hrs.

The approximate usable capacity is ( 12 volts ) x ( 100 amp-hrs ) x ( ~ 75% ) ~ 900 watt-hrs.

Using a 25 watt panel and assuming that it is putting out 15 watt when in the sun, then

( 900 watt-hrs ) / ( 15 watts ) ~ 60 hrs of sunlight to charge it.

( 60 hrs of sunlight ) / ( 6 hrs of good sunlight per day ) ~ 10 days


In the meantime, the renogy charger that you have will use up some of that just sitting there.

Sorry - if my post was not as friendly as it could have been, but now you see why I am suggesting a much larger solar panel setup.

Harry

 

[mikefitz]

Any type of charger will show a voltage slightly higher than battery voltage. The setting in the charger, 14.2v for your charger, is a 'target voltage. As the battery is charged , the voltage will rise, and when it reaches the 'target', its charged.
As suggested more panel watts would be useful. You rarely get full rated power, 70% is typical under good conditions. Add in the fact that your controller is PWM , and in theory cannot get more than around 19 watts maximum from the 25 watt panel. Factor in the 70%, and the typical solar yield is 13 watts.
Assume your battery needs a full charge, its capacity is 160 watt hours, ( edit) at 13 watts per hour that's 12 hours at typical solar input.
Since you can count on 5 'sun' hours a day, that's almost 3 days of sunshine.
This assumes all the power is charging the battery, when you consider the power taken by the controller, ( continious 24 hours a day), charge time could be even longer.

Mike

 

[Novatek]

Any type of charger will show a voltage slightly higher than battery voltage. The setting in the charger, 14.2v for your charger, is a 'target voltage. As the battery is charged , the voltage will rise, and when it reaches the 'target', its charged.
As suggested more panel watts would be useful. You rarely get full rated power, 70% is typical under good conditions. Add in the fact that your controller is PWM , and in theory cannot get more than around 19 watts maximum from the 25 watt panel. Factor in the 70%, and the typical solar yield is 13 watts.
Assume your battery needs a full charge, its capacity is 330 watt hours, at 13 watts per hour that's 25 hours at typical solar input.
Since you can count on 5 'sun' hours a day, that's almost a week of sunshine.
This assumes all the power is charging the battery, when you consider the power taken by the controller, ( continious 24 hours a day), charge time could be even longer.

Mike

I think my battery has closer to 150 watt hours as it is a 12ah 12v lifepo4.

 

[mikefitz]

Yes you are correct, perhaps slightly higher. My error , my post has been edited.

With lithium under charge, the volts stay in the mid 13s volts for most of the charge period .

 

[Rednecktek]

That just means the battery has a long way to go. When it gets close to full it'll start coming up fairly quickly. The charge curve on LFP is really flat.

Also, a 25w panel is nothing. Depending on where you live you could need much much laeger panels.