AGM batteries and Smart Charger

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MB-1-E
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AGM batteries and Smart Charger

My question is regarding how to get the best life and performance from my AGMs.
I have a couple of 6V - 220Ah AGMs in series used basically as a UPS for short term power outages.
I do have solar and wind but also keep a 3 stage "smart charger" on them to keep them topped off.

The same applies to my ebike AGMs which are charged as a 12v bank. I swap the use of the Iota 15A charger with QD4 between the two systems.

According to the charger manufacturer, this charger can be left on the batteries with no harm.

I tend to keep the charger on each for 2-4 days then swap. The charger puts out right at 13.6V float charge and rarely gets into bulk charge or absorbtion unless I am using the batteries quite a bit.

Does this periodic constant 13.6V float charge do any harm or shorten the life of these AGMs or is this method the best way to keep them in top shape?

As noted, long life is my goal.

Just for the record, I purchased my SLA, AGM batteries at:
http://www.ebatteriestogo.com/
and
http://www.tristatebattery.com/

The both seem to have very good prices, free shipping and very good service IMO. So far I'm very pleased with the quality as well.

Thanks

chas_stevenson
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Re: AGM batteries and Smart Charger

Dave,

My system, as you knowm uses flooded batteries but they stay on the charges 24/7 and spend most of their time in float mode on the chargers. My system has been in service since June of 1998, just looked it up, and I just replaced the batteries this month. Several of them were still good batteries but I had at at least 4 of the 16 batteries that refused to hold a good charge. Since I live in the country and this is the backup for my home, Freezers, Refrigerators, Computer backup, and the like I could not afford the system degradation. It seems like we loose power every time we have a little thunder storm. I think you will do just fine leaving them connected. I also have some e-trikes that use AGM batteries and I leave them connected all the time. One of them has a 3 year old pack the other one is starting it's second year and they are still going well. They are a little old and do show some small drop in range but other wise they still operate the e-trikes fine.

Chas S.
My Bicycle Pages

MB-1-E
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Re: AGM batteries and Smart Charger

Hi Chas,

Thanks for the input. It's difficult to really know unless you've had experience with charging them over time.

I think my concern stems from the set of so-called Marine "Deep Cycle" batteries that I used to have for the RV, they didn't last long at all. I'm sure that this was due directly to the RV's cheap, built-in charger and the fact that those batteries were not much better than a car batteries' thin plates.

I'm not used to the AGM's being relatively maintenance free and holding a charge the way they seem to.
When I got them I needed a quality charger. I didn't realize it at the time that I'd also use it later for an ebike. Seems to be working out well.

Sooner of later I'll put a receptical right on the bike so I can just pull up to my charging station and "fill-'er-up" ... :)

Thanks,

Dave

MB-1-E
Electric - Bridgestone MB-1 Mountain Bike
Icon Photo of lighning striking Eiffel Tower Jun 3, 1902, taken by MG Loppe'

Dave B

MB-1-E
<a href="http://visforvoltage.org/book-page/996-mountain-bike-conversion-24v-3-4h... - Bridgestone MB-1 Mountain Bike</a>

chas_stevenson
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Re: AGM batteries and Smart Charger

Dave,

Sounds great. I would be more incline to get another charger for the e-bike.

Do you plan to charge the bike from your backup system charger with the backup batteries attached? (I don't think this is a good idea)

As far as those Marine batteries go they are a hybrid battery. they do have smaller plates so they can be used to start a motor but not as small as a normal car battery. I have 2 in my boat and have to change them about every 3 years. The trolling motor runs from both but has a low voltage cut off. when this happens I can just get the main (gas) motor started. Sorry about the gas.icon_gas.gif

Funny thing happened to my system this past winter, well not funny a bad thing. We had an extended power outage, 3 days, and my generator, being outside in the cold and diesel, failed to start for about a day. This caused me to over discharge the batteries, Maybe why I had to replace them this year. The main chargers would not engage when the power came back due to the battery voltage, 48-volts nominal, was too low. I went out to the barn got my 48-volt e-bike charger and connected it to the large batteries. After about 6 hours the batteries were up enough for the main chargers to start their charge cycle. One more save by an e-bike.... :)

Chas S.
My Bicycle Pages

MB-1-E
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Re: AGM batteries and Smart Charger

Chas,

So far, I've kept the two systems separate and just alternate the charger from the backup to the ebike to keep them both topped off.

You are probably right about not hooking my ebike bank up to the backup. Any potential difference could cause problems with one or the other. I could just put in a switch I suppose.

I'll keep them separate. Eventually I'll get another charger but swapping should work for now as long as I don't let either bank go long without.
Just a little more effort on my part but thats ok too. I like know and monitor what is happening, this gets me in touch with both.

Speaking of which, I need to bring the wind turbine down and do some general maintenance on it ...
I should replace the blades. These are made from 10" PVC pipe and work very well but do get a little brittle after time (Yes I do protect them from UV), I think it's the constant flex. These have lasted a year and a half and are due.

Dave

MB-1-E
Electric - Bridgestone MB-1 Mountain Bike
Icon Photo of lighning striking Eiffel Tower Jun 3, 1902, taken by MG Loppe'

Dave B

MB-1-E
<a href="http://visforvoltage.org/book-page/996-mountain-bike-conversion-24v-3-4h... - Bridgestone MB-1 Mountain Bike</a>

chas_stevenson
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Re: AGM batteries and Smart Charger

Dave,

I would love to see pictures of your turbine and know how you built it. I live on top of a hill with about 2 miles of open farm land to my east. We don't get wind every day but when we do it comes in rather strong, 10 to 20 MPH. Maybe that would be enough to aid on days when the power goes out and give me some more incentive to get off the grid.

Thanks for the in site, lots of help.

Chas S.
My Bicycle Pages

MB-1-E
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Re: AGM batteries and Smart Charger

Chas,

Here are some pics, I appologize for the poor quality (some of the folks on the forum had dial-up, so I had to lower the resolution so they would load for them).

I don't think you have to log on to see them.

http://www.fieldlines.com/story/2005/3/6/52340/90146

My user name there is "arc" (without the quotes) so if you do a search under that, there is quite a bit of information on my particular build(s).
As is the case with most of these things, I went through several versions and a lot of learning.

In general I took 120V AC motor, cut down (squared off) the armature epoxied groups of neo (rare earth) magnets to the armature, rewired the field and starter windings to end up with a two-phase alternator that puts out around 50 watts.
This method is usually called a Permenant Magnet Conversion. Some motors work much better than others. (A 230V low rpm, three phase is a good candidate)

A more robust and much higher output can be obtained by building an axiel flux wind turbine.
These usually consist of two, steel disc rotors with large neo magnets rotating on each side of a set of windings. They are often made from Volvo brake disc rotors since they have a great thrust bearing.

I believe most all of the parts necessary to build one are available on the fieldlines site or can be made with some basic machine tools. One could certainly make the center portion with the windings and put most of the rest together from off the shelf items. A substantial guyed tower would be a consideration and some blades would need to be made but this is the way I'd go if I had the location and budget to do it.

It sounds like you have an ideal location and you would be surprised by how much you could suppliment your grid intake.

Dave

MB-1-E
Electric - Bridgestone MB-1 Mountain Bike
Icon Photo of lighning striking Eiffel Tower Jun 3, 1902, taken by MG Loppe'

Dave B

MB-1-E
<a href="http://visforvoltage.org/book-page/996-mountain-bike-conversion-24v-3-4h... - Bridgestone MB-1 Mountain Bike</a>

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