Solar trickle charger fail!

A 10 watt solar maintainer is not a waste of time, but there are some caveats.

* For optimal results, disconnect the batteries from everything except the maintainer.
* Batteries must be in good shape to begin with.
* Batteries must be fully charged to begin with. That 10w is a maintainer, not a charger. It isn't enough to do more than maintain.

I use one of these on my truck, just plugged into the cigar lighter. If I don't start my truck for a couple of weeks, this keeps my batteries fresh for the next start. Diesel truck so dual batteries just like your trailer. Worse than that, the thing sits on my dash, pointing west, so it only gets direct sun in the afternoon, and through a windshield. This works for me, even during the So Cal winter months when it might be cloudy for hours at a time :) But it is much better during the other 3 months.

So I don't think your solar maintainer was a fail, but I do think your batteries are toast.

I disconnect the batteries for the winter, check voltage about once a month, until the 100 watt solar panel is clear of snow. It doesn’t charge fast but does well over a whole sunny day. Being in a cold winter region, I bought a smart charger, Black & Decker 5, 10 and 20 amp maximum settings. It goes up to 16 volts so I usually disconnect vehicle batteries while charging. An hour or two fully charges a battery from a very low state on the 20 amp setting.

I have used trickle chargers but they are frustrating. Better to disconnect the battery until you can use a real charger.

wa8yxm wrote:
Is your 10 watt panel going through a controller? If so at the best you get a bit less than one amp and if you have a big battery in an RV parasitic loads and self discharge can be more than that.

Also unless there is some kind of reverse current protection (There is in the charge controller) the 10 watt panel takes 'em down in the dark.

The bigger panel likely was used with a charge controller. possibly an MPPT (Maximum Power Point Transfer) these are DC/DC converters that swap volts for amps so you get the maximum power from your panels. they also contain reverse current protection So at night. they "Vanish" electronically

The 10W trickle charger is not going to a controller.

The 100W is.

So, do I get it that the rate of discharge from phantom drain from the RV is higher than my rate of charging on the 10W solar trickle charger?

Again, thanks everyone for the information. I'm buying a battery disconnect switch.

wanderingbob wrote:
Many of us have discharged a battery till it was dead , and then only got another 3 or 4 years out of them . I would not replace that batt with out giving it an honest trial .

Yeah, I want to test and observe first.

And it appears to be charging ok -- so far.

Is your 10 watt panel going through a controller? If so at the best you get a bit less than one amp and if you have a big battery in an RV parasitic loads and self discharge can be more than that.

Also unless there is some kind of reverse current protection (There is in the charge controller) the 10 watt panel takes 'em down in the dark.

The bigger panel likely was used with a charge controller. possibly an MPPT (Maximum Power Point Transfer) these are DC/DC converters that swap volts for amps so you get the maximum power from your panels. they also contain reverse current protection So at night. they "Vanish" electronically

wanderingbob wrote:
Many of us have discharged a battery till it was dead , and then only got another 3 or 4 years out of them . I would not replace that batt with out giving it an honest trial .

Really depends, you can get away with most anything if you really don't mind the lights going out before you want them to or the furnace shutting down in the middle of a cold night or say the water pump and lights in the middle of your nice hot bath.

In a auto, you might be able to get away with a weakened damaged battery for a while in good warm weather but come a cold zero day and you will come up with blanks on starting.

At 9.6V that battery is well below ever being fully recovered, if you could get a charger on it immediately it most likely would recover SOME, but would it be enough to camp on for a an hr, a day, a weekend, or so? At 10.5V the battery starts heavily sulfating of the plates, it is near impossible to reverse this effect and ever minute it is left at that state reduces the hopes of recovery and capacity.

If it is standard Group24 or Group 27, they are dirt cheap to replace, $60 for a group24 and what maybe $70 for a group 27.. That isn't going to break anyone's bank to make the system whole again..

Once the battery has been replaced the OP should be able to get 9, 10, 11, 12 yrs if treated properly. THEN TREAT IT BETTER by making sure the battery is being charged or the battery is disconnected from the RV when being stored! In other words, don't do what you did before!

time2roll wrote:
Seems like a stretch to get from 9.6v to 100% charge with just 100 watts in one day.

Indication the battery is not a happy camper. The voltage spikes premature on bad batteries. We have a dead battery in a car here. Like down to 1v dead. The charger will turn off early because it recognizes whatever voltage it needs to see. So we just keep turning it off an on for weeks now. Every time it puts a few more amps in. The car is a spare POS not the daily driver.

Thanks everyone for this very useful information.

I wish I've met you before I did this foolish thin, lol.

Many of us have discharged a battery till it was dead , and then only got another 3 or 4 years out of them . I would not replace that batt with out giving it an honest trial .

I’ve been happy with a 30 watt solar panel during storage. Full sun however.