Observations and questions about small/pwc batteries

[Ronnie]

I've owned various personal watercraft (pwc) , mostly used, for over 25 years now so i have had to replace many of the oem batteries. Well as luck would have it the shop that is tuning up my son's new to him 1996 waveblaster called to tell me they were done working on it but that battery wouldn't take a charge. I decided to grab a battery at Walmart so that my son and I could possibly test the waveblaster out, weather permitting, when we pick it up later this morning. It wasn't until I was prepping the battery, per the mfgs instructions and as I had done many times before that I started wondering why I had to prep these batteries and not others and why the instructions are written as they are.

this is not a sealed battery like the Optimas, it's a conventional battery similar to the ones found in most of out cars but it is an AGM (absorbent glass mat) which I've read are more resistant to damage caused by vibration. It costs twice as much as its non agm counter-part, at least at wall mart. For those that haven't had to do this before, these smaller 12v batteries do not come ready to use, some assembly is required. This is important to know, especially if you have a dead battery and need to replace it right away in order to get on the water. Generally, to get the battery ready for use you have to add the included fluid to it and let it stand for 30 to 60 minutes before charging it for 4 to 10 hours at a rate of no more than 2 amps. As such if you need one of these batteries for immediate use you have to buy and prep it a head of time (in my case the night before) because of the initial charge interval.

Now that I've outlined the background I can move on to the observations and questions. I think that the reason I have to assemble/prep these batteries and not the ones I buy for my cars or boat because the smaller batteries tend to sit on store shelves longer and the mfgs don't want them to die / go bad prematurely. Also the acts of adding fluid and charging such batteries initially are the the triggers for starting their service lives.

Why don't we use these batteries in our boats? I had a yamaha boat and pwc that used the same engines but nit the same batteries. Maybe its because a boat's battery is hooked up to more than a pwc battery normally is (e.g. Stereo, depth finder, etc.) so a boat's battery needs to have a larger capacity. In dual battery situations like the systems found in the yamaha l and ls models using a smaller battery for the engines could reduce the weight considerably compared to a standard auto battery.

Is the battery acid just distilled water until it is added to the battery and the battery is charged initially? I've had to add fluid to car batteries before and have used, per instructions, distilled water as well as dedicated fluid from the auto parts store. The contents of the dedicated fluid as far as I recall are distilled water and electrolytes (similar to what's in Gatorade, maybe that is why it is yellow not clear).

If the acts of filling and charging a battery are what triggers it's useful life why don't the batteries in cars go through the same user prep? What I'm getting at is, if both types of batteries have 5 year expected service lives and both are manufactured on the same day, shouldn't the larger auto battery die one year earlier if the smaller battery is not filled and charged until a year after it was manufactured?

Why do the instructions require that the battery stand before charging it inially?

The instructions go on to state that charging at over 2 amps is not recommend and will reduce the life of the battery, yet my standard charger has a 2 amp and 6 amp setting and my onboard (boat) charger has a 5 amp setting, many charge at 10 amps. Shouldn't chargers be limited to 2 amps to prolong battery life? Or are the amp charging limits directly related to a batteries capacity? That is the bigger / larger the battery the more charging amps it can handle?

This may seem like a stupid thread to start on a boating forum since most of us don't have to deal with the smaller pwc batteries but I was just curious about everyone's thoughts on my observations and questions. Additionally, I'm trying to understand battery technology a little better now that my son and I are working on his pwc together as I'd like to give him better answers to his why type questions than just "... because the instructions say so." I'm also curious because the latest generation of radio controlled toys that we are getting or have gotten into use lithium polymer batteries that have been known sometimes to malfunction and explode/burn so I have to be more careful about how I maintain those batteries and again I would like to better understand why that is the case.

 

[Bruce]

Until I added the refrigerator I considered a small AGM watercraft or motorcycle battery as a backup to the primary battery. It would work very well for this purpose as long as it was charged correctly.

There is a generally accepted rule of charging a battery at no more than 10% of its capacity per hour. On the 100Ah group 31 AGMs in my boat that would be a 10 amp charge rate. But your small watercraft AGM is unlikely to be more than a 20 Ah battery so the charge rate should be less than a 2 amp charge rate. Here is an article on battery charge rates http://www.homepower.com/articles/s...t-products/ask-experts-battery-charging-rates

I am uncertain if the stators in our boats would charge the small watercraft battery too rapidly. I am sure that a method could be found to limit the charge rate. Charging from a single engine might be a good option.

 

[Big Shasta]

Just off the top of my head I would say the wait time is to be sure the fluid is equally absorbed throughout the absorbent material in the battery since it's an AGM. The charge rate is indeed based on the battery capacity probably due to the lower amount of electrolyte. A higher charge rate would probably boil the fluid out or at a minimum cause excess heat internally.

It's always gentler on a battery to charge them low and slow and not allow them extreme discharge unless they are a deep cycle battery.

 

[MikeyL]

@Ronnie : I was actually shocked reading your post. Here's why.
It was my experience that AGM batteries were actually designed ORIGINALLY for the motorcycle market - for 2 reasons:
1) They could withstand a LOT of ROUGH handling - like what you would experience riding off-road bikes.
aand
2) They were 100% TOTALLY Sealed - AS many times they are mounted sideways in the bikes.
Reason #2 is why expensive AGM batteries are the types selected for German "house batteries" mounted in the trunk. No one wanted to haveta worry about battery fluid spills.
So what is my point now ?
It is my personal feeling that somewhere along the way ......... you may have been sold an "AGM Type of battery" but by no means did you get a true AGM battery.
By the way, PWC manufacturers sell their PWC's with lead-acid batteries from the dealer to the buyer, but I don't have any friends who replace their PWC batteries with anything but true AGMs.
I always mail (ie, InterNet) order my AGM batteries - 1 of the reasons they love to sell AGM batteries is that they ARE SEALED and no one has to worry about fluid leakage in shipping.
Well, I am gonna probably get beaten up for posting this, but the reason I did was in an attempt to be of sincere HELP to you and others. I really do hope it has helped someone.
Best Wishes and Merry Christmas - Mike Lulejian - Lake Oconee, GA

 

[Big Shasta]

Hmmm...not sure @MikeyL I've bought AGM batteries for my motorcycles in the past. I always had to add the fluid to the battery after purchase. I think you're missing the fact that AGM means all the electrolyte is absorbed by the glass mat and isn't available to leak out. It's stays suspended in the mat. That's what makes them spill proof, not the fact that they are completely sealed (although they may be once the cap is on, not sure about that)

 

[MikeyL]

@Big Shasta : I do understand. All I can tell you is this: EVERY AGM battery I have purchased in the past 4 years has been TOTALLY sealed !
There is NOTHING to be "added" and there are no "Caps" whatsover. Just my experience.
And every one of them has come COMPLETELY charged already !@
For me ...... I would not purchase an AGM battery today unless it was of the 100$ sealed type. Which means you can install it upside down and the battery does not care.
By the way ....... for those who do not know ...... AGM batteries MUST be "charged/maintained" differently from lead-acid batteries.
Which is why "today's" charger are either "automatic detecting" as to battery type - or they have a manual switch for Lead-acid and AGM types.

 

[Big Shasta]

@MikeyL Those have always been the steps I've had to take when I bought a new AGM. Maybe it's because I was buying small motorcycle ones just like Ronnie did.

http://www.batterychargers.com/Documents/Xbat Maint free AGM.pdf If you notice the last statement in the steps, it's now a completely sealed battery.

I think you might be confusing yourself with Gel Cells not AGM...an AGM can be charged with a standard charger as long as the rate is set correctly.

http://www.batterystuff.com/kb/articles/battery-articles/gel-vs-agm.html notice that AGM and Gel Cells are Non-spillable and can be mounted in any direction.

 

[Murf'n'surf]

It's an AGM. Good questions @Ronnie

Here a video of someone filling this battery. My local pwc dealer stopped selling agm for PWC because a lot were coming back for warranty swaps. They decided that the standard filled lead acid battery wasn't so bad at 1/3 the cost.

 

[Ronnie]

Hey guys, thanks for all the responses. Most of which I understand and are consistent with my experience.

That is, I've been charging the lipos I use in my rc toys at 1/10th their capacity on the recommendation of the hobby shop I bought them from. So by transfer of logic this rate applies to this small battery for pwcs.

This is a premium (agm) power sport from Walmart, at least that is what the box says and I assume why it was about twice the price of a standard power sport battery. The instructions state that once the fluid is in and the caps are on that they should never be removed and the cells should never be refilled. Removing the caps afterwards voids the warranty.

The stand time makes sense to me now, it took about 10 minutes for all the fluid to drain into the cells so I thought once that happened the battery would be ready to take a charge or be ready for use. Now I realize that the fluid may just be surrounding the absorbent glass mats but they may not be saturated by it for a few minutes. I forgot to mention, the sticker on the side of the fluid container/dispenser says it contains sulfuric acid not distilled water and electrolytes like then 3rd party battery fluid / water I got from pepboys does.

I used to buy gel cells similar to Optimas for my pwcs but the price on those, the last time I checked, is almost twice that of the agm from Walmart. Another reason I don't buy them anymore is because of convenience, I used to get gel cell pwc batteries from the shop that works on my pwcs. I can still do that but they are over an hour away and they are almost never open when I need a battery (e.g. The night before a trip to the water). Where as Walmart is 24/7 and less than 10 minutes from home. My bank account may be happy that Walmart doesn't carry gel cells but the ones I've owned in the past have lasted the longest of the three types I've owned and as @MikeyL stated they where fully sealed and ready to got out of the box, no assembly and no charging (although I suspect that my shop charged them before they put them on the shelf).

By the way. The battery I just replaced is an agm from Walmart as well, it was just put into service in may of 2013, so I got about 1.5 years of service out of it which didn't seem right at first but the Walmart warranty on it is less than that. If this battery doesn't last at least two seasons i will probably switch back to walmarts non agm model. FYI - I keep all of my pwc batteries on charger / maintainers when ever the pwc they are installed in is not on the water.

I still don't understand why my waverunner with a 1,052 cc mr1 engine and the sx 230 (I used to have) with the same engines use different battery sizes. Im pretty sure they have the same charging systems but maybe the difference has to do with the fact that the boat had two engines/ charging systems plus accessories like a stereo system to support.

 

[Cobra Jet Steering LLC]

My experience is The more you let a battery sit the shorter the life. My supercharged 1800 ski had over 4 years on the original battery before it started giving me any issues, but the ski had over 500 hours on it, The rule of thumb is 2 years for a pwc battery with average use. I do check the water in them every 50 hours when I do oil changes and usually they need a little water added from time to time.