Battery Charching Question.

[XSDRD]

I have 2 Maxx-29DC batteries that I question. They are 7 months old. I have a MinnKota Charger which is an onboard MK345PC. I've got a Sears Diehard Platinum AGM battery also 7 months old.
I'm not sure about this concern, I've just started noticing a fairly strong rotten egg smell from the battery compartment when batteries are charging. I've always keep the battery compartment lid on my boat propped open while charging the batteries. My boat is stored under an open carport. I check and if needed fill any low battery cell of these flooded acid battery with distilled water monthly. I've checked all battery cells to bubble as connected to the MK345PC charger. Is this smell normal? If so why is it that I have never smelled it before.
At present I have disconnected the charger from power source till I get some advise in this matter. Thanks Guys!

[CatFan]

Shouldn't be strong. Are the charger banks all showing a green/charge complete lights?

[billnorman1]

My Maxx-29 batteries are about a year old and have never let me down, never used any "water" and do not smell of rotten eggs. Either you are running them too far down, or your charger may be over charging them.

[XSDRD]

Shouldn't be strong. Are the charger banks all showing a green/charge complete lights?

CatFan Just checked the batteries on charge now. Put them on charge yesterday at 5:00pm. These batteries being charged are set up: Bk1-AGM, Bk2-FLA, Bk3-FLA. At present Bk-1 and BK-2 have flashing GREEN lights on while the Bk-3 shows a 3 YELLOW light (75%). I had noticed BK-3 had moved up to a 75% charge status in the past hour.
Now also I noticed the last time I had charger connected to these same batteries on the same time period there has been a different arrangement of lights on showing the state of charge. I believe last time the Bk-2 battery showed 2 Yellow lights on steady while Bk-1 and Bk-3 showed solid green. May not be a concern to worry about but haven't noticed this present odor concern in the past few months.

[moetorola]

Defiantly not a good thing to smell rotten eggs! That is an indication the charger is overcharging one or more of the batteries.

If you are handy with a volt meter, measure the battery voltage of each battery at about the beginning and end of the chargers charge cycle. And then measure again the next day during float charging. And post back your voltages.

Typical charging voltages for Flooded and AGM 14.6 Charging/Absorption and 13.4 Float.


Sounds like you are keeping an eye on the water level in the batteries, this is a good thing few people do on lead acid batteries If you are having to refill often one or both of your MAXX batteries often, either you have a setting wrong or charger is at fault.

If water level drops below the plates, it can have explosive consequences. Several guys on a Facebook group all had a bang, gun shot sound in the back of there boats with in the last few months. Probably due to summer temps and low water level in there batteries. Point is keep a close eye on that water level, until you figure out the rotten egg smell.

This reminds me...My buddy has a 2015 4bank genius charger with 2015 lead acid batteries and will smell just a slight hint of rotten egg smell charging. I need to have him check his battery levels ASAP because it was longer than 6 months ago I remember smelling that smell, last time we fished a tourney!

My rotten egg experience: I had a Minnkota charger MK210 linear style 2 bank (non digital) that one bank was over charging my starting battery (lead acid), it was floating the battery at over 14.5volts!
The battery was replaced under warranty. The charger was not under warranty.

Used the one good bank to keep my lawn mower lead acid battery topped off during storage. Ps: this was my second bad MK charger (first one bad bank out of the box).

I have switched brands! Maybe I just got a bad batch, so I am not suggesting all MK are junk, but after 2 bad ones, can you blame me!

With my new charger I have only had to add water once (2year old battery charger setup)and they really didn't need it, this was after I saw the explosive results of exploded battery mess pictures in the bilge. I walked (actually RAN!) out to immediately check my water levels.

[XSDRD]

Thanks Moetorola Now I did add water in the battery at BK-3 to be 1/4-1/2 inch above the plates last Saturday afternoon. The BK-3 battery was low, below plates, where I added enough distilled water to cover plates about 1/4-1/2 inch. Don't know how long the water was low but this charging cycle is the first time I have noticed the rotten eggs smell. I just checked charging voltage: BK-! AGM bat @ 13.7V(solid GREEN), BK-2 FLA bat @ 12.8V(Flashing GREEN), BK-3 FLA bat (2 solid YELLOW 50% @ 13.7V) this reading is after approx. 15 hours on MinnKota MK 345PC charger. What you think Sir?

[moetorola]

Battery Type: Absorption / Equalize / Float
__________________________________________________ _____________________
Flooded Lead-Acid: 14.4V / 15.5V / 13.2V
__________________________________________________ _____________________
AGM (Absorbed Glass Mat)AGM / High Performance: 14.4V / n/a / 13.4V
__________________________________________________ _____________________
Gel: 13.9V / n/a / 13.4V
__________________________________________________ _____________________


- 25%, 50%, 75% (YELLOW): These LEDs indicate the progress of charging.
- 100% (GREEN): Flashing GREEN LED indicates battery is fully charged in Maintenance Mode and ready to use. Steady GREEN LED indi- cates battery is fully charged in long term Maintenance Mode and ready to use.


When everything has charged and settled down from charging. Check the float voltage the next day.

Keep monitoring BK-3 its seems that may bank or battery with the issue. Charger maybe charging it to long..however the voltage is not as high as I would have expected. So that battery is either pulling a lot of current (possibly a bad cell) or charger is messed up.

Typically: my Trolling motor batteries switch to float mode at the same time, for some reason your BK3 battery FLA is taking longer than the other FLA...of course I am assuming a 24 volt setup and these batteries are hooked in series, but should not matter even in parallel and if purchased at the same time and same make and model batteries.

What I would do.
Since batteries are or should be under warranty.

I would swap charger banks between the MAXX batteries and see if the other battery starts having the depletion in water level. That would tell you that it is that one bank on the charger that is causing the issue.

I would also take the battery that the plates were exposed back for warranty replacement, usually once the plates have been exposed its a junk battery and will never meet spec again. May also be the reason it is taking so long to charge.

I have asked walmart to test the batteries before I purchased them, and I would pick the best out of the bunch, LOL. The employee actually removed 1 battery from the shelf it was so far below spec. (rated 750cca but only had 550cca @ 12.6volts) was only on the shelf a month and another one was questionable. I have also done this at academy, but brought my own tester as academy did not have one. One battery there was removed from the shelf there also, the manager came over and wanted the part number of my handheld tester, said they were going to purchase one.

At first walmart would give me grief, but I would explain that the batteries must be pretty close to matching because they will be in series for 24volts. Finally they tested them. Academy did not have an issue at all with me wanting a test,, heck was even my own tester. LOL

It reads the CCA by a capacitive technique and reads Voltage it does not pull a load on the battery like a typical CCA tester.

I write down the actual CCA on the battery, a new battery will usually by above its rated CCA. Example I picked out 2 batteries that where 750 rated but read 775 to 790 @12.6v

[XSDRD]

Thank you sir I am going at the moment to remove the battery and take it to Walmart to have it replaced.

[moetorola]

Thank you sir I am going at the moment to remove the battery and take it to Walmart to have it replaced.

Ask for manager if they give you a hard time, because they will test it and probably say its good. Typicaly.

[XSDRD]

Thanks again moetorola. Just returned from store I got the battery at in January. Had them test the Everstart Maxx 29DC battery to find it had a dead cell. They warrantied the battery so I have a New battery and now for the temps to cool down enough to spend a day on a lake. Thanks again for the help.

[moetorola]

Great news ,,keep us posted if you smell eggs again!

[XSDRD]

Hope I don't but this time I plan to do the battery condition check at least every other week. I believe the one battery with water level dropping below the plates and ruining a cell.

[billnorman1]

Thanks again moetorola. Just returned from store I got the battery at in January. Had them test the Everstart Maxx 29DC battery to find it had a dead cell. They warrantied the battery so I have a New battery and now for the temps to cool down enough to spend a day on a lake. Thanks again for the help.

A dead cell upsets the whole apple cart. Could be your rotten egg smell, plus it upsets the charger.

[XSDRD]

Thanks billnorman1, I have checked and run several diagnosis procedures suggested by fellow BBC members. I took the battery in question to be tested and found it to have a dead cell. This dead cell caused by my neglect of periodically(monthly) checking and filling each cell of the batteries with distilled water as needed. Lucky me the battery in question was still in complete replacement warranty and I replaced that battery. Installed now and fully charged ready for a full day's use.