Solar Suitcase

Roo19

Total Solar and RV beginner here with what I hope isn't an unsolvable problem.

RV is wired with 2X 6V Golf Cart batteries in series, which has been working nicely.  We purchased a 120Watt Eco Worthy Solar Suitcase to keep us topped up as most of our camping will be without hookups.

 My understanding was that I could connect the alligator clips to the positive terminal on one battery, and the negative on the other, and that would get us charging.  When I connect the charge controller to the battery in this way... nothing.

I've tried it on the 12V battery we replaced with the 2 6V, and it works fine, as well as charging off the USB ports built into the controller.

Any help would be greatly appreciated!

Thanks.

Photowhit

Just a guess, did you hook up the battery first and then the solar panels? Typically the charge controller needs to know the system voltage first, I think that will work on both 12 and 24 volt systems.

The system is polarized, you will want to connect the charge controller to battery + to + and neg to neg.

A couple other things, 120 watts is VERY minimal charging for 2 golf cart batteries, perhaps 6 amps into 220 amp storage or < 3%. The additional capacity may have you running increasingly lower recharging and eventually destroying your battery. Even for weekend use I'd shoot for 5-6%, manufacturers typically want you to have 10%.

...also clips offer a very poor connection, I'd suggest replacing with some ring type connectors. You could replace the nuts on your battery post with 'wing nuts' if you need fast connecting/disconnecting.

Roo19

Photowhit said:

Just a guess, did you hook up the battery first and then the solar panels? Typically the charge controller needs to know the system voltage first, I think that will work on both 12 and 24 volt systems.

The system is polarized, you will want to connect the charge controller to battery + to + and neg to neg.

A couple other things, 120 watts is VERY minimal charging for 2 golf cart batteries, perhaps 6 amps into 220 amp storage or < 3%. The additional capacity may have you running increasingly lower recharging and eventually destroying your battery. Even for weekend use I'd shoot for 5-6%, manufacturers typically want you to have 10%.

...also clips offer a very poor connection, I'd suggest replacing with some ring type connectors. You could replace the nuts on your battery post with 'wing nuts' if you need fast connecting/disconnecting.

Correct.  I followed the instructions which directed to hook up charge controller to batteries first, before connecting controller to the panel.

To clarify: + from charge controller to + on Battery A, neg from charge controller to neg on Battery B.... correct?

Not totally following the minimal charging thread.  Does the 120 Watt panel not produce enough amps to properly charge the 2 battery system?  What are those percentages representing?  How would that destroy the batteries?

Noted on the Alligator clips, will replace with ring connectors.

Thanks!

Photowhit

Yes, Sounds like you have the connections figured out.
Not sure why it wouldn't be working.

Chronic undercharging, if you don't have a specific meter, or even a voltage meter, perhaps just 4 dots on the charge controller. you may be unaware you are undercharging. In addition, I don't know if you set these up as you go or what, campers (at least me) like to park in shade, doubt the solar is often in optimal charging situation to begin with then add that it has maybe 3% capacity to recharge and you may think you are doing okay while the battery bank is actually never reaching fully charged. 

It's not uncommon for people who experience poorly performing systems to add battery capacity and actually make the problem worse! Much better to have a balanced system. 

Note that Trojan T105 data sheet recommends a 10-13% rate of charge as do most battery manufacturers;

(C20 refers to the battery capacity at a discharge rate over 20 hours which is how most batteries are rated)

I don't mind not going strictly by this, in fact it's rare for a home system to actually reach this level, as in general we try not to discharge more than about 25%, so the battery charging is usually at the 80% full level before the sun is high enough for them to accept it's full capabilities. This is different for small system and particularly for weekend system where the demand can be high over a short 1 or 2 day period.

How old was your old battery? Perhaps it was showing loss of capacity? 

I went back and read your original post. Did you hook up your batteries in series? + to - ? What we call batteries, are actually made up of a string of batteries which we call cells, so we hook these cells up in series to produce higher voltage batteries, so your 6 volt battery is actually 3 - 2volt cells hooked up + to -, to make a 6 to use the batteries to replace a 12 volt battery they should be hooked up in series to make a 12 volt battery bank, hence + to -..