Solar battery chargers / maintainers... opinions

[Doofy]

Good to know. Thanks

 

[5030]

If you use any of the insurance company monitors like Allstate's Drivewise module then please note that they have massive parasitic battery drain. They will drain a new battery in just a couple of weeks of inactivity. If you use one of those and dont drive your vehicle frequently, then you need some sort of trickle charger of at least 3 amps.

My carrier wanted me to install one. I declined. No young drivers here and I always drive conservatively. but if I ever did, that is good to know. I assume it plugs into the OBD serial bus under the dash so I also assume it can be unplugged during idle times.

 

[buickanddeere]

Co-worker says the solars don稚 seem to make much of a difference
from when he parks after work and until the next morning.

 

[deserteagle71]

About 10 years ago I installed a 15w solar panel with a charge controller on the roof of my barn and connected it to the battery on my Miller Bobcat welder that I use infrequently. Used to be every time I went out to use the welder the battery was dead. Not one problem since I installed this unit and the welder is still on the same battery. Expensive - but it does what it claims. The controller will not allow the unit to overcharge/boil the battery.
https://www.northerntool.com/shop/tools/product_200328565_200328565

 

[5030]

About 10 years ago I installed a 15w solar panel with a charge controller on the roof of my barn and connected it to the battery on my Miller Bobcat welder that I use infrequently. Used to be every time I went out to use the welder the battery was dead. Not one problem since I installed this unit and the welder is still on the same battery. Expensive - but it does what it claims. The controller will not allow the unit to overcharge/boil the battery.
https://www.northerntool.com/shop/tools/product_200328565_200328565

Bongo. Just ordered one. I have no electricity in the barn.

 

[Doofy]

I also have a 15 watt solar panel with a charge controller. This unit has been great for charging auto/truck batteries. The unit that ruined my 4-wheeler battery was a 7watt panel with no separate charge controller. Perhaps the 7 watt was to much for a small battery.

 

[cooksmtn]

I've been watching this thread, and feel I need to chime in.
I've lived off grid in a cold climate since '75 and know a bit about batteries (my homestead runs on solar).
Flooded lead acid batteries (what's being discussed here) have a pretty definite set of voltage parameters for charging. A good charge controller (or charger) will have three modes, Bulk, Absorption, and Float. Bulk charging will send as much power as the battery will take without going over approximately 14.8 V. Absorption will hold the voltage at that point by controlling current, for about an hour. At that point, Float takes over, holding the voltage at 13.2 to 13.5 V by controlling current. All these voltages are plus/minus a few tenths of a volt.

If the battery doesn't go above 14.8 volts, it's not gonna boil. By the same token, if the charge never gets to 14.8 volts, the battery never really gets fully charged. And these numbers are all based on relatively warm temps. Cold outdoor winter temps dramatically increase the voltage necessary to fully charge a battery.

And... a battery at 0ｰ has roughly half the capacity of one at 70ｰ (numbers off the top of my head, but close).

Solar battery maintainers without a controller are typically going to put out their rated wattage at about 13.2 to 13.5 V, never fully recharging a battery, but maintaining it at a full charge. If this battery is on a piece of equipment, it will get fully charged by the functioning charge system. If it is on a gate opener, or fence charger, it will never get fully charged, and it's life will be limited. Batteries like to be fully charged. In fact, large deep cycle batteries should get what is called an equalizing charge on a regular basis, which is really just a controlled over charge, causing the batteries to "boil", which tends to de-stratify the electrolyte. For instance, my house batteries get an equalizing charge about once a month, running up to 15+ volts for about an hour.

Previous comments have mentioned having a solar panel with a charge controller working well. Some have mentioned battery maintainers "fying" small batteries, such as found on small engines. The amount of current needed to "boil" a battery is directly related to it's size (measured in Amp hours.

I previously mentioned using a small solar maintainer on diesel truck batteries here, and maintainer is the key word. I don't depend on them to recharge the battery. I also use one on a battery used for electrolysis rust removal, again, for maintaining. When doing electrolysis, I hook up a charger.

Bottom line, you get what you pay for. A small panel with a three stage charger will cost about ten times as much as a maintainer, but will take care of that (expensive) battery.

As a side note: I recently put a digital voltmeter on my Mitsubishi, since I hate idiot lights, which is all it had. I'm glad I did, as the voltage regulator wasn't functioning, allowing uncontrolled voltage 15+. The alternator light only lights for non-charging. My battery would have boiled dry in relatively short order. After replacing the voltage regulator (Thanks, Valley Power), I saw the numbers mentioned above. Start, run up to 14+V for a while, drop back to 13+ for the rest of the time running.

 

[ultrarunner]

Bongo. Just ordered one. I have no electricity in the barn.

I'm trying to order and use my Northern $25 gift card and site will not let me complete...

Been on telephone hold for 33 minutes but operator cannot help as gift card can only be redeemed online which isn't working.

My guess is a promotion is ending tonight and system swamped...

 

[PEJ5]

I've been watching this thread, and feel I need to chime in.
I've lived off grid in a cold climate since '75 and know a bit about batteries (my homestead runs on solar).
Flooded lead acid batteries (what's being discussed here) have a pretty definite set of voltage parameters for charging. A good charge controller (or charger) will have three modes, Bulk, Absorption, and Float. Bulk charging will send as much power as the battery will take without going over approximately 14.8 V. Absorption will hold the voltage at that point by controlling current, for about an hour. At that point, Float takes over, holding the voltage at 13.2 to 13.5 V by controlling current. All these voltages are plus/minus a few tenths of a volt.

If the battery doesn't go above 14.8 volts, it's not gonna boil. By the same token, if the charge never gets to 14.8 volts, the battery never really gets fully charged. And these numbers are all based on relatively warm temps. Cold outdoor winter temps dramatically increase the voltage necessary to fully charge a battery.

And... a battery at 0ｰ has roughly half the capacity of one at 70ｰ (numbers off the top of my head, but close).

Solar battery maintainers without a controller are typically going to put out their rated wattage at about 13.2 to 13.5 V, never fully recharging a battery, but maintaining it at a full charge. If this battery is on a piece of equipment, it will get fully charged by the functioning charge system. If it is on a gate opener, or fence charger, it will never get fully charged, and it's life will be limited. Batteries like to be fully charged. In fact, large deep cycle batteries should get what is called an equalizing charge on a regular basis, which is really just a controlled over charge, causing the batteries to "boil", which tends to de-stratify the electrolyte. For instance, my house batteries get an equalizing charge about once a month, running up to 15+ volts for about an hour.

Previous comments have mentioned having a solar panel with a charge controller working well. Some have mentioned battery maintainers "fying" small batteries, such as found on small engines. The amount of current needed to "boil" a battery is directly related to it's size (measured in Amp hours.

I previously mentioned using a small solar maintainer on diesel truck batteries here, and maintainer is the key word. I don't depend on them to recharge the battery. I also use one on a battery used for electrolysis rust removal, again, for maintaining. When doing electrolysis, I hook up a charger.

Bottom line, you get what you pay for. A small panel with a three stage charger will cost about ten times as much as a maintainer, but will take care of that (expensive) battery.

As a side note: I recently put a digital voltmeter on my Mitsubishi, since I hate idiot lights, which is all it had. I'm glad I did, as the voltage regulator wasn't functioning, allowing uncontrolled voltage 15+. The alternator light only lights for non-charging. My battery would have boiled dry in relatively short order. After replacing the voltage regulator (Thanks, Valley Power), I saw the numbers mentioned above. Start, run up to 14+V for a while, drop back to 13+ for the rest of the time running.

Great details CooksMtn. Taking good care of batteries is likely the most important part. As you state, one needs enough charge capacity to get batteries fully changed and stop discharging before batteries are depleted. What is your system's shutoff voltage? Is it built into your charge controller?

 

[cooksmtn]

My charge controller is set up as a diversion controller, sending excess power to my water heater.
My inverter has a default disconnect voltage of 10.8, which is way too low. I monitor my system closely, and have never seen less than 12.0 V, typical morning voltage is 12.4.
Recent weather has been very cloudy, so near the end of the day, if necessary I will run a 50A charger.
My cabin system is very basic, I have a stand alone system at the laundry shed that is actually a bit more sophisticated, on NiCd batteries. It powers a freezer and occasional stationary power tool use.
I previously had a large system in my shop, which burnt down about 5 years ago. I am just now getting siding on the shop replacement and will be building a large system there.

You are right, battery maintenance is top priority. I've replaced batteries for people who never checked them letting the batteries boil dry. Expensive lack of maintenance.