Solar trickle charging

[k0ua]

Well unhook one clamp off of each battery then put your digital volt meter leads on the 10 amp scale in series between the post and the lead and measure the current draw in amperes. Then you will know. You can get a rough idea even without a meter by unhooking a car battery's leads and hooking them back up in a darkened garage.. Little spark, small parasitic current draw.. Big spark, large parasitic current draw.. But of course an actual figure would be best.

 

[94BULLITT]

You need to wait 15-30 minutes for all of the modules to shut down. He may need to check on a lower setting than 10 amp depending on how bad the drain is.

 

[k0ua]

You need to wait 15-30 minutes for all of the modules to shut down. He may need to check on a lower setting than 10 amp depending on how bad the drain is.

Correct, but you always start on your largest scale when measuring currents to keep from burning out your meter shunt. You can also measure current by inserting a precision know value shunt in series from the battery to the load and measuring the voltage drop across the shunt with a voltmeter. For example, take a 1 ohm 5 watt resistor, and put it in series, and measure the voltage drop across it. calculate the current in amperes E=IR. or watch the smoke escape from it if the current draw is more than you expected. :shocked:

 

[Jkott]

I tried measuring the load on my duramax and it was "difficult".

When you first hook the battery back up through the ammeter, between the computer powering up and the courtesy lights all coming on, it's over 10 amps (60 watts) for a bit. And when things settle down, parasitic drain of 0.2a isn't perceivable on the 10 a scale and you have to break the circuit to switch to lower current, which reboots everything.

I never did get desperate enough to create jumper clamps to power things through a larger cable and then switching to the ammeter without losing continuity.

You will probably have to remove a few fuses if you want to measure real parasitic drain.

For me just put my gps on an ammeter and threw it in the freezer. **** thing never stopped charging the internal battery if it was in the freezer and was draining a half amp and hour. Why Chevy didn't put any switched cig lighter outlets in I will never understand. They are all always powered.

 

[k0ua]

I tried measuring the load on my duramax and it was "difficult".

When you first hook the battery back up through the ammeter, between the computer powering up and the courtesy lights all coming on, it's over 10 amps (60 watts) for a bit. And when things settle down, parasitic drain of 0.2a isn't perceivable on the 10 a scale and you have to break the circuit to switch to lower current, which reboots everything.

I never did get desperate enough to create jumper clamps to power things through a larger cable and then switching to the ammeter without losing continuity.

You will probably have to remove a few fuses if you want to measure real parasitic drain.

For me just put my gps on an ammeter and threw it in the freezer. **** thing never stopped charging the internal battery if it was in the freezer and was draining a half amp and hour. Why Chevy didn't put any switched cig lighter outlets in I will never understand. They are all always powered.

You bring up some good points about the variable nature of the loads in a modern vehicle with microprocessors booting up and dang courtesy lighting coming on briefly, again controlled by microprocessors. I hadn't thought about that.. Onstar radio's could be another drain I didn't think about.. The GPS sounds like a real problem. 500ma. is quite a bit of drain, especially in cold weather. In the old days when you turned the key off the car was dead, except for an electric clock winder once in a while.

 

[LindenBruce]

I don't have any GPS or Onstar or any of that stuff. It could still have a glove box bulb hanging on. My truck is on 06 model I bought in October 05. Had it since it was new. It's always had an issue of draining batteries if it sits to long. I guess I could get out in that cold 20something weather and run a draw test with my DVOM. Maybe I will try it tomorrow or Friday and report back. My 12v outlets are powered all the time also.

 

[Jkott]

I don't have any GPS or Onstar or any of that stuff. It could still have a glove box bulb hanging on. My truck is on 06 model I bought in October 05. Had it since it was new. It's always had an issue of draining batteries if it sits to long. I guess I could get out in that cold 20something weather and run a draw test with my DVOM. Maybe I will try it tomorrow or Friday and report back. My 12v outlets are powered all the time also.

Wireless key entry system? Alarm system?

Do you last days, or barely weeks? Might help narrow down the level of draw.

Dual batteries? Don't rule out one battery being possibly being bad at two years. One bad battery will actually charge from the other, draining both.

 

[Gordon Gould]

Sounds like you guys don't think having a controller or "minder" is worth the money to prevent over charging the battery or am I miss reading you.
I am thinking about getting a solar charger for my little dozer down in the woods. There is no parasitic drain because the master switch disconnects the battery (2 of them). I would want it to recharge even if it was slow. The temps here are 0* F and below on winter nights. I thought I would need the 15 watt model with the controller but from what I am reading here maybe I could do it cheaper. What do you think ??

 

[Soundguy]

You could still have something draining your battery, a radio, glove box light or a module.

them glove box lights will get you.

i had a 98 dodge i sold to work.. it developed a BAD parasitic drain. a 3 day weekend would make it a hard starter. tab in t e glove box broke, letting the ?? 168 or 194 bulb burn full time.....

 

[k0ua]

Gordon I think that since you don not have any parasitic loads on your dozer, you very may well get by with a small unregulated solar maintainer. Keep in mind these units wont really charge a discharged battery, or would take a very long time to do so, but are designed more to keep up with the inherent self discharge of the battery itself. A little harbor freight unit for 10 bucks might very well do what you need, if your needs are just to make sure the battery is kept up while it sits for weeks or months in the woods. But such a unit may very well not work for someone with a sophisticated pickup truck with a lot of parasitic drain parked at an airport for a month.

James K0UA