Warning: Always leave gen auto-start on

[Ben]

I just returned from a five day trip to Boston. When I returned to my bus, I unlocked the door and noticed that my entry handle (which is usually lit up giving me enough light to easily enter the coach) was giving off almost no light and the coach had a strong smell. I immediately knew that the power was out and that the fridge/freezer must have defrosted and the food got stinky in the hot Florida weather.

So, what happened? My shore cord break was turned on, but somehow my shore cord got loosened from the socket (it was almost falling out). I always push it in tight and the bus had not been moved for at least a week and ran fine off that shore power, so I'm somewhat suspect that someone might have un- and re-plugged my coach while I was gone. A simple push of the plug caused the bus to come back to life.

Since the power was out long enough to cause a very stinky bus and almost zero light coming from most controls, I'm assuming my batteries are hosed.

How do I go about testing the batteries to judge their health and does anyone have advice for replacements if they are needed?

Lesson learned: ALWAYS leave your generator auto-start feature turned on when you will be away from your bus for more than 24 hours, even when it's plugged in (and make sure you have enough fuel to let it run a while). I wouldn't have had a problem had I had the auto-start feature turned on. I always have it on when I'm on the road and don't remember turning it off, but must have.

[Joe Cannarozzi]

If you don't run them down like that too often they should charge back up.

In fact, it's mabye not prefered, but you should be able to do that to a good set about 10 or 12 times before they are no good.

[Orren Zook]

I'd let the batteries charge up before getting too worked up about changing them. After they have reached full charge you can probably get a heavy duty distributor or RV house to load test them to see if they are OK. If they don't pass muster, then you can replace them with the batteries of your choice. I would recommend a AGM battery over other deep cycle types available.

A newer type of sealed battery uses "Absorbed Glass Mats", or AGM between the plates. This is a very fine fiber Boron-Silicate glass mat. These type of batteries have all the advantages of gelled, but can take much more abuse. These are also called "starved electrolyte", as the mat is about 95% saturated rather than fully soaked. That also means that they will not leak acid even if broken. AGM batteries have several advantages over both gelled and flooded, at about the same cost as gel type batteries.

Since all the electrolyte (acid) is contained in the glass mats, they cannot spill, even if broken. This also means that since they are non-hazardous, the shipping costs are lower. In addition, since there is no liquid to freeze and expand, they are practically immune from freezing damage.

Nearly all AGM batteries are "recombinant", this means that the Oxygen and Hydrogen recombine inside the battery. They use gas phase transfer of oxygen to the negative plates to recombine them back into water while charging and prevent the loss of water through electrolysis. The recombining is typically 99+% efficient, so almost no water is lost.

The charging voltages are the same as for any standard battery - no need for any special adjustments or problems with incompatible chargers or charge controls. And, since the internal resistance is extremely low, there is almost no heating of the battery even under heavy charge and discharge currents. Most AGM batteries have no charge or discharge current limits.

AGM's have a very low self-discharge - from 1% to 3% per month is usual. This means that they can sit in storage for much longer periods without charging than standard batteries. The Concorde batteries can be almost fully recharged (95% or better) even after 30 days of being totally discharged.

AGM's do not have any liquid to spill, and even under severe overcharge conditions hydrogen emission is far below the 4% max specified for aircraft and enclosed spaces. The plates in AGM's are tightly packed and rigidly mounted, and will withstand shock and vibration better than any standard battery.

Even with all the advantages listed above, there is still a place for the standard flooded deep cycle battery. AGM's will cost 2 to 3 times as much as flooded batteries of the same capacity. In many installations, where the batteries are set in an area where you don't have to worry about fumes or leakage, a standard or industrial deep cycle is a better economic choice. AGM batteries main advantages are no maintenance, completely sealed against fumes, hydrogen, or leakage, non-spilling even if they are broken, and can survive most freezes.

[lewpopp]

Mr Zook,

Holy Mackeral !!!!! Thanks for the very informative post on the AGM batteries. You even seemed to make sense at 5:07 in the AM

Lew

[Ben]

I called my sales person at Liberty (Gary) asking who I should call about having the carpet shampoo done to get any stinky liquids out near the fridge. It being a holiday weekend and all, he said he'd have to call me back since he wasn't in his office. In less than 30 minutes, the shampoo guy was knocking on my door, ready to clean the carpets... and I was just expecting a call back from my sales guy to get a phone number!

Thanks for all the info on batteries. I'll unplug soon and see how long it takes for my gen auto start to kick in, which should give me an idea if they can still hold a good charge.

[Joe Cannarozzi]

That is some pretty outstanding coustomer service.

Did ya get everything cleaned up good?

Is it safe to say that if your full timing the auto-start never gets shut off?

Or at least switch it on EVERY time you leave, and that is a good habit everyone should be using, in case of power failure, while plugged in with the inverters running.

[Ray Davis]

Ben (and others),

I've heard, but am not sure, that the generator auto-start battery is only charged from the generator. Not, from normal driving, nor when plugged in to shore power. Does that sound correct? Or does it vary between converters.

Point being if you don't run your generator very often, your auto-start battery might be in bad shape too. I just had to replace my gen battery, but I've never used auto-start.

[jello_jeep]

My gen bat has a small solar panel on the roof trickling it as well as whatever else charges it.. FWIW..

[Jon Wehrenberg]

I'm not sure we can make a blanket statement about what charges our generator start battery. I think that is something that each converter may do in its own manner.

Based on my voltage gauge I would strongly suspect mine is being charged with the generator off, but my bus connected to shore power, in addition to when the generator is running.

[truk4u]

On my Marathon, the gen batteries are charged with a solar panel (like Jeeps) and not charged by shore power. The only other charge comes when running the gen. So in theory, while parked in the garage, it could go dead, but mine holds up real well and has a cutoff switch if needed.

Warning - don't leave the auto-start on while garaged!