I would like to revisit an earlier thread about recommendations for battery chargers. I am a Do It Your self guy  who likes to build my own gear which I can tweak to send me a text message about the status of a battery :(

However, many coaches and mentors have express that a disproportionate amount of their frustration with the project relate to battery management. So, I would like to look at a couple 'simple'  best practices.

1. What charger do your use? From a thread back in 2010 some people mentioned these chargers.

Lester (25 amp battery charger that will charge up to 16 volts per battery)
Manzanita Micro (37 amp charger, fully adjustable, but more expensive) 

Guest, model16102, 2 bank, 12/24 volt, 6 or 12 amp, any lead acid battery, you may leave it  connected all year, about $ 135

2. What are you charging strategies? A couple of people have vented about needing to remind their teams to recharge their batteries after a run. This seems to be most frustrating when a full discharge battery sits for a couple of days or weeks after being fully discharges during a race.

3. How do you avoid over discharging your batteries? Especially during a competition, there is a tendency to push things past their past their optimal discharge voltage to get that last couple of feet :(

4. Finally, what strategies do you use to maintain your batteries. During the offseason, how do you maintain the large banks of batteries teams tend to accumulate.

As alway, thanks for any feedback public of private.

David

Look into a brand called Iota. I charge my batteris in parallel, it's easier for me compared to doing it in series. Plus, Iota has several options not just in 12 volts, but 24, 48, and last I checked a 240 volt input. The number of amps depends on which series you're looking at. For example, I have the DLS30. It's a 12 volt that puts out 30 amps at full current during charging. I used the Optima batteries for a good four years, at the end of a race I would get the batteries out and hook them up with the practice batteries. Or leave them in the car to charge them up (separate subject right there for in car charging.) Recently I swapped to what Dave Cloud is running (see separate post by Dave in the batteries section of forum,) that is now a 36 volt system. Fortunatley I don't need a different charger since I charge in parallel. I know Dave had to get a different charger since he charges in series. To clarify any concern of if you would ruin batteries in parallel I've never had a problem. As long as the amp hour rating is higher on the battery compared to the charger you'll be fine. Plus if you know, connecting batteries in parallel doubles the amperage. So, if you had three batteries (as in my case) totaling 36 volts at 26 amp hours in series. Then when charging in parallel you then have 12 volts at 78 amp hours. If you just charged one battery at 30 amps then you will run into problems. For me with the new batteries it takes around four hours or so to get them charged back up. When I was running the Optima yellow top batteries it took around three and a half hours or so.

Another cool thing with the Iota chargers or the sister companies that use the same technology (Cascade Audio based in Bend, Oregon) is they all have a voltage plug. What it does is with the 12 volt chargers is put out a higher voltage with the plug in. With the plug out, the 12 volt chargers sits at 13.6 volts, plug in it jumps up to 14.2 volts. This has been helpful for me during race day, I'll leave the plug before I need to take the charger off. Plus concerning about your maintenance question, Iota also sells a IQ4 option. What it does is transform your charger into a smart charger. It keeps tab on your batteries connect to the charger. It'll do a bulk charge followed by an absorption charge then a float charge. After seven days of inactivity the charger jumps the voltage back up to break up any sulfation that may have accumulated inside the battery. I would like to get this option for my one charger I currently have. Since I don't have an IQ4, I have a timer that I got from Home Depot I wire up that plugs into the charger. I set it to turn on during the weekends for 48 hours or something like that, then it shuts off at midnight on Monday morning, then kicks back on Wednesday for 24 hours then back off at midnight. It works for me since I don't have that option at the moment. The Cascade Audio one is an older version that I can't do the IQ4 option on (current versions which are Iota sister copies can use the IQ4). They had a IQ3 adapter but Iota no longer makes it.

Myself and Mike Hodgert use these types of chargers. I only have two while Mike has 12 in his battery truck. But Mike also can charge up to 96 batteries at once, 8 batteries for every one charger. Iota is also very helpful for customer service and the chargers have a two year warranty last I checked.

Over discharging is part of the game in electrathon. As long as you don't let your batteries sit dead for too long (no longer than four to six hours) then you'll be fine. After I get weighed in after the race for driver checks I get back to the pits and start charging the batteries back up. Rule of thumb I've always done is to charge back up after a race as soon as feasibly possible. If I'm recharging on the road I'll run a generator with a cord going to the charger to get things charging on the road. I've never had problems with doing this, just make sure things are strapped down tight if you are doing this.  Mike and anyone else feel free to clarify stuff I've said.  

Here's the website for Iota, the chargers are not that big and don't take up too much space.
www.iotaengineering.com/dls.htm

Thanks Zaine,

That helps a lot. It looks like a team needs to set up some sort of matrix with three levels when choosing a charging systems:
1. Beginning racer, low budget. As cheap as you can go without prematurely damaging your batteries.
2. Competitive racer, mid level price. With a little hacking you can consistently get good results and long battery life.
3. Winning racer, a higher price level. Industrial quality equipment with variable settings for optimal performance.

As you describe, the Iota DLS-30/IQ4 sits well within the competitive racer category.

I like the capability of hook up and forget. I currently bulk charge with an old 45 Amp transformer based charger until the batteries reach my set bulk charge voltage. Then I switch to a smaller smart charger to do the absorption charging and float charging for storage. I hadn't thought of how to do the burst charging.

"At the end of a race I would get the batteries out and hook them up with the practice batteries." I am a bit unsure about what this means. Probably because my theory has not caught up with your practical experience.

Do you connect the pair of fully discharged race batteries in parallel with the full charged pratice batteries at allow them to self balance? My understanding is that parallel charging batteries with similar starting voltages is fine. The batteries see the same output voltage from the charger and as you say the current is just divided between the batteries.

The potential problem occurs when the voltage between the batteries is too dissimilar. This can result in excessive current flow to level out the voltage between batteries. That is a significant issue with Li-po where I have done most of my testing. I did notice that a cheap utility battery got uncomfortably warm when I connected it (in a fully discharged state) to a pair of full charged redtops.

I haven't run the same test of connecting a fully discharged and fully charged redtop. I don't have the budget to risk damaging the batteries until I understand the situation more fully. In theory, if the internal resistance it high enough it shouldn't be a problem.

Thanks again for taking the time to discuss this on the forum. In the long term, a new team is probably better off spending $400 dollars on proper battery charging and maintaining equipments if it will prevents them from prematurely damaging a $400 pair of batteries.

On a final note, what do you use for wiring harnesses for you chargers and maintainers? I solder a 50 amp fuse inline with each set of lead on the 45 Amp bulk charger. I always charge in pairs with that set up so each battery should only have a max current flow of 33 Amps if everything is working.

For the smart charger which I use for topping and storing, I run a 10 amp fuse inline with each lead. It is set up to handle between two and eight batteries.  If any individual battery sees 10 amps there is a problem.

I use inexpensive alligator clamps on for the battery end of things. When a pair of leads is not in use they are stored hot by clipping to short lengths of PVC painted red and black. It is this final bit of storing the leads hot that seems unnecessarily risky. Have you come across any good connectors for quickly disconnecting unused pairs of connectors?

A battery truck capable of handling 96 batteries! I have a hand truck for hauling pairs of batteries around on my wish list for next year:)

David

The thing with connecting the batteries in parallel with a set of red tops after the race is for a couple things.
1. It's a two day race. This way I know my batteries will be fully charged up in a couple hours. Plus with the practice ones inline with the discharged set helps to bring the dead ones up. It takes a bit for them to dump half of what the practice ones have into the race ones after a race. Mike Hodgert does this with his batteries in the truck. The only trick with using Mikes set up is for every two drawers (four batteries each) you have to be paying attention. For every two drawers is one charger charging up to 8 batteries all at once. The batteries balance one another out over the course of a couple hours when recharging them. His students have run into problems with getting discharged race batteries if there are two seperate heats at a race for the day (which is fairly common in the Northwest.) If someone comes back with a dead set of batteries and puts theirs into the drawer, the full practices sets and any race set that may be in the drawers will start to fill the two dead ones back up. Mike does have the drawers setup so one can be disconnected while the other is connected to the charger. It works for him for all of the years he's had the truck.
2. They'll all be at the same voltage anyway. Unlike series charging (which I don't do,) I like the parallel stuff much better. All the batteries in line with one another all balance out. Keep in mind these are all lead acid batteries I'm talking about. I think you could do the same with LiPO batteries no problem. Guys I've talked to who have RC cars will charge in parallel to balance out batteries when charging up. The only concern would be the ages of the batteries you are using. I wouldn't feel comfortable with connecting two batteries that have say a ten year difference on a fresh set. It could cause problem, main concern with age difference is if there are any batteries with shorted cells (will feel hot with the Optima batteries on one of the six cylinders or cells on a normal box battery.) You just have to keep an eye on things when charging. In all of my charging experiences you can get away with hooking two race and two practice batteries in parallel no problem. Just check for hot cells and if there are then the battery set that has the bad one should both be tossed.

When I was using the Optima batteries I was using a threaded post terminal on the batteries. When charging I would put a wire between the batteries I was charging up with a ring terminal on each end. This way they will not come off during the drive down or back from a race. On the chargers I have gator clips and put them on the batteries accordingly to complete the connection. Again, Mike does the same thing with his batteries. His however go one step further; once the batteries are all hooked up you then have to shut the drawer. Once shut then you hook the last two wires that come out of the drawer to the wires near the box that go to the charger on top of the entire shelf. Once connected the charger goes to work. This way the batteries can not be messed with without the drawer being open. The only catch is all batteries must be hooked up correctly (red on positive, black on negative) or they will short out. A lot of smoke comes out of the truck and I've seen the smoke a couple of times from the truck.

With what I would like to do with my car is the batteries stay in the car to charge back up. They would still be in parallel when charging which is what I want to happen. The only difference is now the charger just plugs into the car after changing the switches in the car to take the batteries out of series and puts them in parallel. On electric forklifst this is very common, Anderson plugs are a pretty fool proof way to not get wires mixed up. I litterly would just plug the charger in via the plug in the car with the plug on the charger and it goes to work. There are enough amp hours when in parallel that the batteries would not be harmed by the charger to get away with it. Speaking of the Anderson plugs, you could do the same for your chargin set up instead of the gator clamps. The link has the ones I got. They make other versions that go up 1/0 or bigger wiring, but the 8AWG 50 amp one should work fine for what you could do.

www.ebay.com/itm/ANDERSON-POWER-PRODUCTS-PLUGS-W-INNER-PINS-8-GAUGE-SB50A-600V-SMALL-RED-50A-/130671601434

Check your inbox for a drawing. It should help so there are no hot wires sitting around unless you intentionally stick your finger into it. Hope this helps a little.

Zaine