Posted by Jim Wilkins on June 22, 2011, 11:41 am
If these are simple series charge controllers with diodes the lowest
voltage battery will hog the current since the higher voltage in the
other batteries will reverse-bias their controller diodes. I can't say
that it WILL work without checking in person with a meter. Some lawn
tractor batteries are very cheaply made and may require a higher than
normal charging voltage to force current into weaker cells.
Do you invert your 12V to 120VAC? If so, a regular trickle charger
might be simpler overall, or take the battery home occasionally.
Here is an expensive example of a battery charger that runs off 12V:
They need to contain an inverter to raise the output voltage above
their input voltage.
If you can tinker with electronics these have a useful 12V - 12V DC
Posted by ...........Rob on June 25, 2011, 6:10 pm
I have a 85W solar panel charging my battery operated lawn mower, runs
through a C12 charge controller. I also ran another controller (one of
those cheap on/off that comes with those 15w panel kits) off the same
85W panel to charge a small 12v sla battery (5 amp hour). Been
running two controllers off the same panel for about 2 years and have
had no problems.
$5 -$0, a little wire = problem solved.
Posted by Jim Wilkins on June 25, 2011, 10:35 pm
The OP wrote:
"My weekend cabin has:
42 watt Kyocera panel
2 100 amp hour Power Sonic Sealed Lead Acid Batteries
1 Morningstar Charge controller Sunsaver 10
I have just been given a riding mower that has a 12 volt battery that
may need to charge from time to time. "
If the batteries are left on charge between weekends they should all
fully charge, or overcharge. My comments were directed toward
discovering a low battery on Saturday morning and trying to charge it
while powering everything else.
Posted by clare on June 22, 2011, 12:32 am
Depends a lot on how big the tractor battery is. Most are about 35 Ah
- so a 42 watt charger, capable of producing NO MORE than 3.5 amps,
will NOT have any danger of harming the battery due to too high a
At 14.2 volts, which is the peak charging voltage of a 12 volt battery
(or very close) that is only just a hair under 3 amps.
Posted by DLC on June 26, 2011, 3:20 pm
On 6/21/2011 3:41 PM, DLC wrote:
I thank everyone for their suggestions. I now know several approaches
NOT to use.
I am now considering a 5 watt 12 volt solar panel dedicated to keeping a
charge on the mower battery.
If the battery is seriously discharged, I can still fire up the generator.