Equalizing batteries

[walt]

Stu asked a good question about when I had equilized my batteries and I wanted to start a new thread on it. I have a trailer sailer so the trailer forum might be better place for this but..

What I have for charging is a 20 watt solar panel (just ordered a 40 watt) with a PWM charge controller, I have an old Honda BF8 outboard which puts out typically 1 to 2 amps when running and a 5 amp battery maintainer. These charge two group 27 wet cell batteries.

The batteries are going on the third season and in the previous two years, I likely undercharged them (just got the battery monitor this season) including drawing them down way too much at very cold temps. The batteries have also stayed in the boat over the winters in a cold place (no problem with the cases cracking from freezing however). I just spend a week on the boat and the batteries did overall fine (used maybe 10 to 15 amp hours per day, the batteries never got over 20 amp hours down) but the battery voltage seems lower than it should be for the charge state - like often around 12 volts. The other thing I notice is that if I start with fully charged batteries and for example use 20 amp hours, I have to put a fair amount more than 20 amp hours back in to reach "full charge" again. Like maybe 30 or even 40 amp hours. Part of that could be self discharge but the loss seems high.

None of the charging stuff on the trailer sailor boat have an equilize function. So I think Im going to have to buy some sort of stand alone AC plug in battery charger which has an equilize funtion.

Any recomendations?

 

[Chuckbear]

Walt, A 20 Amp charger without an adjustable regulator will only put out 20 amps for a short time then drop down significantly, which is why you say it takes more than what you perceive as 20 amp hours back in. You don't have the equipment to equalize your batteries so you have two choices. Buy a charger that will allow equalization, the Iota is a great example at really reasonable prices, or take it to a battery shop on a regular basis for equalization. The Iota will automatically equalize your batteries without you doing anything but you will need to leave it plugged in and connected to the battery. Here is our example at http://tinyurl.com/cybgo7 . Chuck

 

[Stu Jackson]

New Question

Walt, buy a TrueCharge 20.

Or investigate more solar.

This is a new one on me that I hadn't ever considered before: for folks with BIG solar systems that keep their banks up properly - how do they equalize their banks?

 

[walt]

One thing I forgot to mention about my battery "abuse" was that I didnt check fluid levels for about 2 years because where I had them made this a huge pain. Ive since moved them to make checking the fluid easier but maybe this makes me a candidate for AGM batteries..

Some more detail on my 20 amp hour charging. I fully charge the batteries with a three stage regulated 5 amp battery maintainer - the voltage says something like 14.4 and the battery monitor is reset. The battery monitor shows exactly 5 amp when its charging. Ill go for some period of time - maybe 2 weeks - with the battery monitor not hooked up using the boat and only charging with solar and the outboard. After this time period, the charge monitor will say Im down say 20 amp hours. Ill hook back up the regulated battery maintainer and the charge monitor will show 5 amps going back in. When the charge monitor says I am back to 0 amp hours, I still have 5 amps going into the batteries and the battery voltage is 13's or so. Right before I left on my recent trip, I went through this process and I probably had the 5 amps going into the batteries for many hours (longer than overnight - but I didnt note the details) after the charge monitor said I was back to 0 amp hours. Im guessing I had to put back in over 50 amp hours - maybe more. (edit - that is 50 amp hours after the charge monitor said I was back to 0 amp hours)

If I had a 20% self discharge per month, in two weeks, this would be 20 amp hours for a 200 amp hour battery bank. I beleive I had to put back in a LOT more than 20 amp hours to get back to where the battery maintainer and the charge monitor "thought" I had full charge. Since I did not have the battery monitor when the batteries were new, I dont know how new batteries behave. But seems lots of things are showing these batteries have seen better days but Id sure like to see what equilizing does.

Im hoping to find a relitively inexpensive battery charger (like from a hardware store) that has the equilize funtion.

 

[Stu Jackson]

Im hoping to find a relitively inexpensive battery charger (like from a hardware store) that has the equilize funtion.

You won't.

I'm not quite sure I understand why you disconnect your battery montior and your #s don't make sense.

 

[walt]

Woops, the Battery monitor is never disconnected. The 5 amp battery maintainer is not plugged in to AC for weeks at a time and during this time (in my example), the battery monitor will show a net 20 amp hours down from use. Please let me know which numbers dont not make sense, Ill attempt to explain.

This is not on the sailboat but I have an old Blue Sky MPPT solar controller (probably 5 years old) which has an equilize function (push a button to equilize). Its also rated for 25 amps and I have 10 amps from the panels under full sunlight. I dont know how many amps/battery capacity you need to equalize?

Ive been looking for the hardware store solution for some time so you may be right about not finding anything. The True Charge 20 has some sort of automatic battery maintinence (every 20 days or something like that) but that would imply it needs to be plugged in all the time to know when 20 days has transpired. I rarely have the boat plugged in to AC (trailered boat).

 

[kloudie1]

Check this out, Walt.. I've used it for over a year and am really happy. Lets ya keep water in 'em without the hassle!
http://www.basspro.com/webapp/wcs/s...1_52557_225007000_225000000_225007000_225-7-0

 

[Captain Dave]

I have 2 Battery Banks. One Bank is 2 (6 volt) batteries, and the other is a Series 27 (12) Volt Battery. The Inverter/Charger I have is a 30 amp with an Equalizer button on it. The Charger charges all the Batteries. Can I use the Equalizer or will it cause a problem between the 6 volt and 12 volt batteries.?