Battery maintenance question

Wprather · 07-13-2019, 04:02 PM

My two batteries both say "Maintenance Free". I've never heard of Maintenance Free 12V Lead Acid batteries. I thought you had to always make sure you had the proper distilled water level in them? It looks like there are screw caps that I can remove on these. I have not tried to remove them. What do you think? Are they really maintenance free? Do I have to check the fluid level, etc?

Thanks!

TitanMike · 07-13-2019, 04:23 PM

Yes, there are Maintenance Free lead acid batteries but when used as "Deep Cycle" batteries they are more "Reduced Maintenance".

This type of battery uses a different palate compound. Still made of lead but also incorporates other metals that reduce gassing and loss of water. The caps used on these batteries are also designed to condense any water vapor released and return it to the battery resulting in far less water consumption than a plain "lead" battery.

The trade off is that maintenance free batteries are less robust than the batteries using heavy lead plates like golf cart and fork lift batteries.

AGM batteries take this one step farther where the gases released are re-combined into water which remains in the sealed environment of electrolyte absorbed into glass matting. These are more truly maintenance free.

On the battery you pictured, look carefully at the portion of the top that is under the battery cables. Chances are that whole portion of the cap can be pried off (carefully) and you can then access the individual cells to check electrolyte levels.

Find an edge and pry carefully. See if the cap is truly separate and just held in place where protrusions snap into the cell access holes.

CHICKDOE · 07-13-2019, 07:13 PM

i also have a couple of 12 volt maintenance free batteries. they have been installed just over 4 years and all indications are that they are still doing just fine. most of the time we stay at full hookup sites. they power the refrigerator during travel times. i have never had any caps off or added water. the other thing is that i have not had any corrosion on the batteries or in the compartment. overall, i am quite pleased with them.

Wprather · 07-13-2019, 07:13 PM

Quote:

Originally Posted by TitanMike

Yes, there are Maintenance Free lead acid batteries but when used as "Deep Cycle" batteries they are more "Reduced Maintenance".

This type of battery uses a different palate compound. Still made of lead but also incorporates other metals that reduce gassing and loss of water. The caps used on these batteries are also designed to condense any water vapor released and return it to the battery resulting in far less water consumption than a plain "lead" battery.

The trade off is that maintenance free batteries are less robust than the batteries using heavy lead plates like golf cart and fork lift batteries.

AGM batteries take this one step farther where the gases released are re-combined into water which remains in the sealed environment of electrolyte absorbed into glass matting. These are more truly maintenance free.

On the battery you pictured, look carefully at the portion of the top that is under the battery cables. Chances are that whole portion of the cap can be pried off (carefully) and you can then access the individual cells to check electrolyte levels.

Find an edge and pry carefully. See if the cap is truly separate and just held in place where protrusions snap into the cell access holes.

Thanks Mike! The flap you mentioned would not come off, BUT each of those Cap/Screw looking things did unscrew and give access to each cell so I could look in and check the water level. They were all above the plates so I just put them back on. I ordered a battery load tester today that measures the volts then puts a 100Amp draw on the battery for a very short time and then measures the drop in volts during the draw and based on that concludes the "state of the battery". That will be my next test of the batteries. Also ordered a battery hydrometer now that I know I can get access to the cells, so I will check that as well.

Thanks again for the info.

**bikendan** · 07-13-2019, 07:18 PM

Quote:

Originally Posted by Wprather

Thanks Mike! The flap you mentioned would not come off, BUT each of those Cap/Screw looking things did unscrew and give access to each cell so I could look in and check the water level. They were all above the plates so I just put them back on. I ordered a battery load tester today that measures the volts then puts a 100Amp draw on the battery for a very short time and then measures the drop in volts during the draw and based on that concludes the "state of the battery". That will be my next test of the batteries. Also ordered a battery hydrometer now that I know I can get access to the cells, so I will check that as well.

Thanks again for the info.

I prefer a hydrometer to test a battery, than a load tester.
A load tester only test the whole battery, at that moment, not each cell's condition.

Wprather · 07-13-2019, 07:42 PM

Quote:

Originally Posted by CHICKDOE

i also have a couple of 12 volt maintenance free batteries. they have been installed just over 4 years and all indications are that they are still doing just fine. most of the time we stay at full hookup sites. they power the refrigerator during travel times. i have never had any caps off or added water. the other thing is that i have not had any corrosion on the batteries or in the compartment. overall, i am quite pleased with them.

Good to know, thanks!

Chuck_S · 07-14-2019, 08:09 AM

That "battery tester" is designed for starting batteries which require a large amperage draw for a few seconds to start engines. Something that deep cycle batteries are not designed to do. A starting battery can show fine with a voltmeter but fail under high load. If the voltage drops below 9 volts under loadthe battery is bad. This same test can be run by switching on the headlights and watching how dim they get when cranking the engine -- if they go out the battery is bad.

I have no idea what they'll show when testing a deep cycle -- I have one I use on my cars occasionally.

A dozen "brands" all appear to have been made in the same PRC factory.

-- Chuck

TitanMike · 07-14-2019, 01:22 PM

Quote:

Originally Posted by Wprather

Thanks Mike! The flap you mentioned would not come off, BUT each of those Cap/Screw looking things did unscrew and give access to each cell so I could look in and check the water level. They were all above the plates so I just put them back on. I ordered a battery load tester today that measures the volts then puts a 100Amp draw on the battery for a very short time and then measures the drop in volts during the draw and based on that concludes the "state of the battery". That will be my next test of the batteries. Also ordered a battery hydrometer now that I know I can get access to the cells, so I will check that as well.

Thanks again for the info.

Glad to be of assistance.

Keep them watered, fully charged, and put a Victron BMV-712 battery monitor on your Christmas Wish List

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