Solar trickle charger for chassis battery......Good or bad?

[SJ-Chris]

Especially for winter storage, for my RV (and boat) I was thinking of getting a simple 20w solar trickle charger to keep the chassis battery topped off.

I see simple ones like this for ~$25-$30:
https://www.walmart.com/ip/20W-Solar-Panel-12V-Trickle-Charge-Battery-Charger-Maintainer-Marine-RV-Car-T-IT/681175652

They seem to come with simple clips to connect directly from the panel to your battery terminals. No charge controller.

I've been learning more and more about solar for the house batteries (...I've got a 200w system and a 500w system I'll be installing soon on 2 RVs). Those "house battery" systems all of course have charge controllers which makes a lot of sense. The simple ~20w trickle chargers don't seem to come with (generally) charge controllers....just wires hooked up directly to the solar panel clipped to your battery.

My question is: Is it smart/good for the chassis battery to be trickle charged constantly with something simple like this that doesn't have a charge controller? It's hard to find voltages on a lot of these simple trickle chargers (...a lot say "12 Volts", but if they mean exactly 12.0 volts I don't imagine that is useful). Would a constant (....when sunny I guess, so not really constant) 13.0v or 14.0v trickle be okay for the health of the chassis battery?

Maybe they don't need a charge controller because the amps they put out is so small??? 20W seems like it would only put out about 1amp or so.

Let me know your thoughts.

Thanks!
Chris

[valhalla360]

Install the big solar system and a good quality controller (that will cut out when the battery bank is charged) and call it done. No need for a second system.

If you can't get the big system installed, a 20w should be pretty harmless. They typically don't include a controller because it's not putting out enough juice to boil off the battery fluid. Of course a small charge controller is pretty cheap so if you feel like you want extra insurance, no real harm.

[D_E_Bishop]

I installed a 200watt system from Windy Nation and the controller has an external out put which I have connected a 12vdc programmable timer. I programmed the timer to provide a half hour charge three times a week for topping off the charge to the coach battery. Works good for me.

[Gjac]

For winter storage I would just charge my batteries fully then disconnect the negative cable and recharge in spring. Self discharge in cold weather is very slow compared to summer temps. I do the same thing for my chassis battery and boat batteries also.

[time2roll]

Yes it appears the 5 amp is discontinued. :(. Could look for some old stock.

http://www.lslproducts.net/index.html

[RoyB]

I have one of these 10W Solar panels always sitting on the dash of my truck plugged into an always hot 12V Receptacle...



My Truck start battery is always ready to use. I am getting up in age now and don't use my truck like I used to do... Truck usually sits in a spot that gets direct sunlight thru the windshield for a few hours each day...

Have not had any boil out of fluids and Battery sees to be always ready for use when I need it to start...

Roy Ken

[SJ-Chris]

SJ-Chris wrote:

time2roll wrote:
Are you going to use this on the RVs that will soon have solar? If so I recommend a Trik-L-Start combiner instead.

For the RVs with solar, I'm going to order this:
https://www.rvupgradestore.com/Ultra-Trik-L-Start-p/tls-oem.htm

5amp seems like plenty for the chassis battery, right? There is a 10amp version that costs twice as much, but that seems like overkill to me.

If this is hooked up to my RV with solar, it seems like it would be able to steal a few amps per hour if needed for the chassis battery and that should be PLENTY to keep it fully charged. Am I missing anything here?

Thanks!
Chris

PS: RV tinkering is addictive.....

Ugh! I can't find the 5amp version anywhere online. Did they discontinue it? Let me know if you know where to find the 5amp version. Otherwise, I'll have to go with the 10amp version that is twice as much.

Thanks!
-Chris

[SJ-Chris]

An interesting word of caution about the Trik-L-Start device.....

https://artontherun.art/2015/11/25/trik-l-start-a-word-of-caution/

I hadn't thought about that...

[SJ-Chris]

time2roll wrote:
Are you going to use this on the RVs that will soon have solar? If so I recommend a Trik-L-Start combiner instead.

For the RVs with solar, I'm going to order this:
https://www.rvupgradestore.com/Ultra-Trik-L-Start-p/tls-oem.htm

5amp seems like plenty for the chassis battery, right? There is a 10amp version that costs twice as much, but that seems like overkill to me.

If this is hooked up to my RV with solar, it seems like it would be able to steal a few amps per hour if needed for the chassis battery and that should be PLENTY to keep it fully charged. Am I missing anything here?

Thanks!
Chris

PS: RV tinkering is addictive.....

[SJ-Chris]

Here's an inexpensive option with a charge controller:
https://www.ebay.com/itm/20W-Solar-Panel-12V-Trickle-Charge-Battery-Charger-Kit-Maintainer-Marine-RV-Car/392929424106

I'll be using it on my boat that sits for a good 6 months out of the year...would be nice to be able to keep the batteries charged and with the charge controller I would hope that it handles it correctly...

-Chris

[racer4]

This solar battery charger has a MPPT charge controller.

Suner Power BC-20W Solar Battery Charger Pro

[pianotuna]

20 watts is more than I'd be comfortable with--except that it is NOT 24 hours a day.

[pianotuna]

X3 on the Trik-L-Start.

[SJ-Chris]

time2roll wrote:
I have a truck and trailer. And since the trailer has solar I keep them connected. I have the Trik-L-Start connected over the truck isolation relay. Works perfect.

I think I have a good picture of how that would work...thanks!
Since I'm going solar on my RVs, I'm definitely going with this approach and just be done with it!

time2roll wrote:

20 watts might be too small for a large set of batteries or too large for a small start battery depending on how much sun you get. May want to monitor the situation a bit depending on conditions. I had 15w maintaining 4 batteries and it was never really enough even in sunny so cal.

I still am curious however (...would apply for my boat, or someone else reading this considering a trickle charger for their chassis battery...) for a ~20w trickle charge kit without a charge controller, is it okay to simply connect those clips to your chassis battery and leave it for weeks/months at a time? Is the current so weak (~1 amp) such that you don't need to ever worry about overcharging/etc?

[time2roll]

I have a truck and trailer. And since the trailer has solar I keep them connected. I have the Trik-L-Start connected over the truck isolation relay. Works perfect.

20 watts might be too small for a large set of batteries or too large for a small start battery depending on how much sun you get. May want to monitor the situation a bit depending on conditions. I had 15w maintaining 4 batteries and it was never really enough even in sunny so cal.