MPPT charge controller battery charge help-draining v quickly (1 Viewer)

[vannewb]

Hi,

I have an Epever solar charge controller and 2 x 110AH batteries. I'm a bit confused as to whether this is reading the batteries correctly.

I have 2 x 185w solar panels and I attached the batteries today and it said they were at 68% . It was a cloudy day but after 15 minutes it says that they are full (I feel like this should be unlikely!) I don't have any load plugged in but over the next hour or two they are gradually down to 60%....but it says the volatage is 13.8V. I'm really confused! They are brand new batteries but I did have a bit of an incident yesterday where I thing I managed to short them as there was a massive spark and the positive terminal on one of them has melted a bit. However even before I did this they seemed to say they were charging and then suddenly drop without me having them attached to any load.

Any help would be much appreciated!! Let me know if you need any extra info.

 

[berni109]

which order did u connect it up in?
batteries first then the solar panels!
disconnect everything from the controller and start again.
might be good to fully charge batteries before reconnecting then u know where u are starting from.

 

[vannewb]

Hi!

When I had the short I think it was because I attached the negative lead first by accident ... that's all I can think??
Otherwise I always have the breakers on for the charge controller and fuse box until I have the battery connected then I click these so they are connected and then turn on the solar last. I'm not sure how to charge the batteries away from the solar panel. Any recommendations??

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[berni109]

U not got a hookup lead and on board charger?
Take the batteries out and charge - but this assumes u have a standalone charger.
That's me out of ideas.

 

[Phill D]

I think you need to check the batteries out and then charge them away from the van first. A stand alone battery charger if you have one.

A major short that is sufficient to "part melt" a battery terminal could have done some damage to one or more of the internal plates.

 

[pappajohn]

I think you're relying too much on solar. 13.8v is probably the solar voltage but the batteries are getting very little charge via solar.
The sun is too low, when there is any, and daylight hours too short to give any real charge.

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[vannewb]

Thanks for the replies will see if I can get a charger of some kind. See if the batteries hold charge. They were like that before the short though.

 

[Jev88]

Sounds like your batteries have had it anyway. The 13.8 is the voltage coming from solar panels, not the charge actually held in the batteries, especially if they are kapput! Have you measured voltage of each battery when everything disconnected or OFF (including solar) for a few hours to see what they read then?

 

[Raul]

vannewb
You are reading to much into what the charger tells you. It can not know when battery is full, half empty or 68%. What it does it reads the voltage and estimates the state of charge. Take this with a very large pinch of salt. If you have no loads, leave the batteries on solar, and let the charger take care of it. To estimate SOC reading voltage , it will have to be voltage on rest, no charge and not discharge, then 12,7v is fully charged. Anything higher, is indicating tats charging until 14,4v, then will drop in float to 13,6-13,8v The true voltage is at night when finished charging. As for the short, it may or may not done any damage. I would carry on as normal and monitor any gassing.

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