Solar system stopped charging

[larn555]

I installed a 100w flexible panel on my car roof and a 100ah battery.

I have a Rover PG 20A controller, I noticed that the battery was dropping and eventually battery was dead, so I tried to charge up the battery from
an external power , I gave the battery 13.5v for a few hours and it got up to 75%, when i disconnected the power, it dropped down to 40% right away and then gradually battery drained again.

On the solar charge controller it has an error code E1 (battery over discharged) and the battery icon is flashing.

Do you think the battery is faulty? or could it be another part? the battery is only about 16 months old

The controller seems to be drawing in around 10v today, so i think the panel is working

 

[12VoltInstalls]

If the battery dropped to 40% without a load a) resting volts are less than apparent charging volts, but b) that is indicative of a battery that has been deeply discharged and damaged or it has reached the end of its service life.

I see “hot air” which I assume is a heater? If you’ve been using electric heat and you run below roughly 12.1V your battery will have been damaged and likely requires replacement.

 

[HRTKD]

@larn555, maybe it's just your drawing, but I'm not a fan of daisy chaining connections like that. Implementing a set of common bus bars like shown below would clean up your wiring a bit.


Is your inverter on? If it's on then it's drawing power. Check to see if there is a low power mode, or simply turn it off if you don't need it on.

 

[larn555]

Thank you for your reply, the hot air is only a small 300w , but I guess that could be it

 

[ianganderton]

Thank you for your reply, the hot air is only a small 300w , but I guess that could be it

300W is 25Amps. With a 100Ah battery that’s just 2 hours to get to 50% with no other draw

300W is quite a lot on a small system

 

[MisterSandals]

100w flexible panel on my car roof and a 100ah battery.

A 100W panel flat on the roof of a car will not produce much.
Even at 100W and 5h per day (these are summer numbers!), that is 500Wh.

Your battery is 100Ah x 12.8V = 1280Wh. So it would take almost 3 days at optimal conditions to fully charge your battery (from battery over discharge condition).

And your inverter probably uses more power than you realize, especially if its turned on 24/7. Do you know how many watts or amps of idle power it uses?

 

[fratermus]

the hot air is only a small 300w , but I guess that could be it

As others have said, that is a huge load for 100w of panel and 100Ah of battery. If alternator charging isn't part of the mix then IMO 100w of panel is likely insufficient to keep 100Ah of lead-chemistry battery healthy.

Related: battery murder

 

[larn555]

actually I don't use the hot air continuously, I use it for less than 5 minutes per day and have LED lighting, I do phone repairs, so i have to heat up the edge of a screen to loosen the glue, each phone I would use it for less than 1 minute, I have used this system for the past 16 months

 

[MisterSandals]

actually I don't use the hot air continuously, I use it for less than 5 minutes per day and have LED lighting, I do phone repairs, so i have to heat up the edge of a screen to loosen the glue, each phone I would use it for less than 1 minute, I have used this system for the past 16 months

We have no idea what your actual power usage/needs are which is why an energy audit is always recommended (even as late as post #9 in a thread).
There are links to a couple in my signature. You will learn more about your solar in this step than any other step.

 

[Bud Martin]

Isn' 100Ah Lead acid battery has actual usable capacity of 50Ah.
300W of power on the AC output will require > 25A due to conversion loss, add 20% to the number will be around 30A on the DC side of the inverter.
OP, what kind of battery are you using? It sounds like lead acid and it is damaged due to over discharge.

 

[12VoltInstalls]

Thank you for your reply, the hot air is only a small 300w , but I guess that could be it

That’s a 25 Amp load. If your battery is a lead battery that’s 2 hours running, tops.

EDIT:
Oops
Already been answered in multiple

300W is 25Amps. With a 100Ah battery that’s just 2 hours to get to 50% with no other draw

300W is quite a lot on a small system

 

[larn555]

What would be a highest voltage i could input to the battery safely? I think I'd like to try charging it up again.

It is a lead battery

I don't know the idle power of the inverter , it says it's 3000w

 

[12VoltInstalls]

What would be a highest voltage i could input to the battery safely? I think I'd like to try charging it up again. It is a lead battery

Is it an AGM/sealed battery or a flooded lead acid battery?

A lead acid NOT sealed/AGM needs distilled water added occasionally to keep electrolyte above the top of the plates. If a marine/flooded lead acid battery you should check that first, and top up with distilled water from the grocery store. Then it can be ‘equalized’ at 15.2-15.8V for an hour or two. That ‘may’ recover some capacity. It may not.

A sesled/AGM lead battery cannot be ‘equalized’ like a flooded battery. It will either be further damaged or worse: it could rupture (although unlikely to rupture). AGM max charge limit is 14.8V tops but 14.6V is more normal. An hour or so at 14.8 should give a battery that has any life in it a “full charge” but it will not hold in the 14V range- it should settle to (guessing) 13.8 to maybe 12.8 if any life is left. If the battery is wrecked a 14.8V charge for an hour or so shouldn’t do more damage but it may not recover the battery at all, either.

 

[TEV]

What would be a highest voltage i could input to the battery safely? I think I'd like to try charging it up again.

It is a lead battery

I don't know the idle power of the inverter , it says it's 3000w

Just measure how many ampers it's taking from the battery, with no load on it.
For what you need, I won't even bother with solar, just connect your inverter to the battery of the vehicle. 100W solar panel it's only good to keep your phone charged ?.