doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Multiple battery charger?

My gun club is in need of something to charge several deep cycle car batteries used in sporting clays at once.
This is a double gun site, yes, but some of the smartest people I have met contribute here, and I need their help. I went to the "Great Northern" side by side shoot in Medford WI, and they had one.
What are they called? My stumbling around the internet only produces little battery chargers.
Sam Ogle, Lincoln NE

I Googled these up using the search term "Multiple golf cart charger"

https://www.batterystuff.com/battery-chargers/multi-bank/7-up/

Best,

Mike

Golf cart battery chargers are typically either 36 or 48 volt, and they are meant to charge three or four 12 volt deep cycle batteries that are connected in series. But they usually have ring terminals on the charging leads rather than the large alligator type clamps used on most battery chargers. Something like this would also work:

http://www.sears.com/schumacher-electric-se4020-10-40-200-wheel-charger/p-SPM6299660701

You could charge one battery at a time or you could charge several that are connected in parallel. Of course, fully charging one battery at 40 amps is going to take less time than charging three or four that are hooked together in parallel.

Precautions should be taken when charging lead acid batteries. Hydrogen gas is produced while charging, and connecting or disconnecting under power can create a tiny spark which will cause a battery to explode violently. I once was asked to check out a golf cart that wouldn't run. I immediately noticed a lot of corrosion around the battery terminals and felt that would be a good place to start. I asked if the golf cart had been on charge and was assured that it had not been plugged in for several hours. It turns out this information was wrong. I commenced to remove one of the leads and as soon as I broke the connection, one of the deep cycle batteries exploded. It sounded like an M-80 going off and the entire top of the battery case blew off. I got sprayed with battery acid and a piece of shattered plastic cut my neck. Thankfully, I had safety glasses on and was close to a restroom where I could quickly rinse the acid off my face. I later learned that this golf cart had been on charge until shortly before I was asked to fix it.

Sam,

Also tell them the best money they can spend is for a little solar panel charger to sit on the ground beside each trap's battery. Orient it to the south. It will save taking the batteries in for recharging many, many times.

SRH

The best charger for your purposes will depend on the type, size, brand and number of batteries in your array. AGM batteries use different charge profiles than do typical flooded lead acid batteries, and that charge profile is critical to optimizing battery performance and life. Big batteries take bigger chargers, especially with big AGMs. Certain brands, like Odyssey, like higher input voltages (14.7+) than other batteries that are happy with input voltages as low as mid-13s. The best source for generic multi-battery chargers is generally in the marine market, since boats tend to have multiple batteries and are often hooked up to shore power for recharging and conditioning the batteries. If the batteries for the throwers are not close enough together to charge off a single charger, then solar is definitely worth considering. If you are planning to haul the batteries into a shed for recharging, the better chargers will not only charge but will recondition and desulfate old batteries, extending their useful life. A higher amp smart charger will work faster for obvious reasons, but when it is in multiple battery mode, it will generally time-slice the charge depending on the number of batteries connected at any given time. Generally you don't want to discharge FLA or AGM batteries below 50% of rated capacity, even for deep cycle batteries, so monitor state of charge fairly carefully when they are out in the field. A solar panel and controller will make this task much less onerous. Solar controllers and smart chargers will put the battery into a float or maintenance mode when full charge has been achieved, and this will tend to extend useful battery life. The best high-tech smart chargers seem to be coming from companies like Ctek, Schumacher, and Optimate, but there are lots of others out there. I have one from each of those three manufacturers, and they each function somewhat differently and for different purposes. Be sure your batteries can accept the maximum amperage that your charger will deliver. As an example, my particular Schumacher is a 40-amp unit designed for high amp, high voltage charging of Odyssey AGMs, but Optima cautions to never use that charger on an Optima AGM. My Ctek delivers 14.7V+ so works fairly well with Odysseys, but my Optimate maxes at 14.6V and can't muster a full charge on a big Odyssey, but works great on everythng else. It all makes a difference, and you local battery shop may not appreciate the subtle differences. Costco sometimes has great deals on solar setups, but a stray pellet or shard of broken clay can take out a panel, so placement is important.

Most sources say that conventional deep cycle batteries should be discharged to at least a 10% DoD (depth of discharge), but not more than 50% DoD before recharging for maximum life. AGM batteries should also be slightly discharged before charging, so float or solar chargers will not be the best choice for maximum battery life with these types of batteries. Better charge controllers for solar systems are designed to prevent overcharging, and also to prevent charging until the batteries have been discharged the proper amount. The convenience of not regularly bringing them in for charging may be outweighed by considerably shorter life unless you buy a very good solar charging system that has a good charge controller. Float or maintenance mode is great for maximizing lifespan of regular lead acid car batteries, but not so good for conventional deep cycle or AGM types. See section 7 of this link. It is one of the better ones on the internet that is still easy to understand:

http://marine-electronics.net/techarticle/battery_faq/b_faq.htm

Depends on who you talk to. Odyssey strongly recommends multi-stage charging at just about the highest amperage you can muster, and then floating their batteries in pulse mode when they are are not in regular use. All Odyssey batteries are AGM deep cycle. Any 12V automotive battery that is powering a target thrower will easily be partially or deeply discharged every week that the club is operating. Depending on frequency and intensity of use, even a pretty big solar panel may not be able to keep up on shoot days, so a good controller is important.

Wow! I knew you fellows would know what I was looking for: I not only found out, but have been taught things I didn't know. Our club is in a "rebuilding" phase, and I was out helping the real workers of the club, standing in the mud earlier this week; starting sump pumps, re-wiring poor connections on the machines, and went into the storage shed where there were a lot of batteries sitting there which needed charged. Please understand I am only teasing when I say of this bunch: "If you ask him what time it is; he will tell you how to build a watch!"
Thanks to all of you, and I am a more learned and humbler guy.

I run a clay shooting ground with around 45 traps which means I have around 60 batteries to keep topped up. I just keep it simple - 4 standard chargers - suitable for heavy duty charging (diesel engine size - I think they are 8 or 12 amp hour jobs)- connector strip to give me 8 sets of charging leads per charger and I just connect them up in parallel. I use all the same sized batteries i.e. 85ah sealed leisure type and an overnight charge tops them back up after a couple of shoots. Batteries normally last 3 - 4 years so it must b working OK. Obviously don't leave on too long and overcharge. Complicated charge protection circuitry doesn't work too well as it gets confused with the multiple batteries. 8 batteries per charger works well as it doesn't seem to overload anything or blow the protection fuse. Hope this helps.
John

Actually Oldfarmer, 3-4 years of life for conventional lead-acid deep cycle batteries is fairly short. If you look at the lifespan table in section 7 of this link, you'll see that marine and golf cart batteries can last up to 6 years, and I have seen some that lasted up to 8 years.

http://marine-electronics.net/techarticle/battery_faq/b_faq.htm

I've also seen lead-acid stationary and traction batteries that lasted 20 years or more. It all depends upon how well they are maintained and monitored. Standard chargers do a good job on batteries in good condition, but sometimes we neglect and abuse our batteries by incorrect charging, discharging, and by the environment or way they are used. That's where some of the types of chargers Replacement mentioned earlier really shine. The new technology smart chargers can reverse damaging sulfation that causes premature failure, and they utilize microprocessors to deliver the charge in an optimal manner.

I kinda cringed when Sam mentioned finding a bunch of discharged batteries in a storage shed. Depending on how deeply discharged they were, and if the shed is unheated in his Nebraska climate, they may have suffered damage that a conventional charger cannot overcome. They may still take a charge and seem OK, but their capacity and overall life may be reduced. Batteries aren't getting any cheaper. Proper maintenance and a good smart charger can quickly pay for itself. But as Replacement also pointed out, there are differences in batteries and smart chargers. Very good information is available for folks who want to get the most out of their batteries.