Charge FAST from your car...

[Burgerman]

http://www.wheelchairdriver.com/charge- ... om-car.htm

JoeC and other heavy users or sport powerchair users. I just tested my charge from car leads in anger as my batteries were down to about 12.1v (24.2) after going on a long dog walk! They felt pretty dead and I lost lots of lights... So I started the van and connected up one battery at at time via the leads and the socket in the van as I drove.

Each battery charged at 100 amps exactly to begin with (clamp meter) and this gradually dropped over the next 15 mins to a more sedate 30. And stayed there for a bit and then as they became charged (14.4v dead on vehicle output voltage) the current dropped away to around 2 amps at which point they are around 90 percent charged or more. Safely. And it takes a surprisingly short time. From all but dead to 90 percent in under half hour. Of course there are 2 so you need to do both and measure the current so you can stop at the same point - say 2 amps to keep them equally charged.

This was all with AGM Odyssey batteries. Which is allowed by the manufacturer. After all there is another one fitted to the van anyway! It gets that same current everytime you fire it up. Same with the deep cycle Optima. And any Starter battery or deep cycle/starter. And as an authorised Optima dealer I can tell you that thats also perfectly safe and expected and not unusual.

I tried it with less deeply discharged batteries and its unbelievably fast.

I also tried it with some MK Gels.

They take longer because the voltage is easily "pulled" up to 14.4 and less current is needed to do so because of their inferior higher internal resistance. Probably takes twice as long. But its still perfectly safe practice according to MKs area rep. Then get very slightly warm. But below the 50c that the manufacturer specifies as max.

Of course you need to charge them individually with a proper 3 stage charger to balance them every day/few days too.

So no charger needed and very easy fast charging in the field. Literally in a field in my case!

[JoeC]

Not from the car, but away from the house- what do you think of this one?

http://www.batterystuff.com/battery-cha ... S2725.html

You know I like to do things a little conservatively, that's why I'm only aiming for charging 3X faster than everyone she practices with, but what do you think of the bulk charge voltage? 14.76 volts per battery seems a tad high to me.

Here's the manufacturer website description of their charging method:

http://www.iotaengineering.com/iq.htm

I know you had a great suggestion of using a portable bench power supply to do the charge, but I haven't been able to find a suitable one that's significantly cheaper than this. They are all underpowered, not switching, or have no outputs. I know what the atmosphere can be like at a tournament, and trusting me to babysit a power supply with a multimeter (and bringing all the right parts to do so) is asking for disaster. Much more peace of mind to build something that I know I can walk away from.

[Burgerman]

http://www.wheelchairdriver.com/fast-ch ... lchair.htm Fast charging! And chargers.

That charger will work fine.
The Optima can be connected directly to a 14.7v Alternator in a boat designed for AGM batteries and it will safely charge a dead Optima at 175 amps. They do get slightly warm but still only around 50c. Ask me how I know this!

The manufacturer states that there is no maximum inrush current limit whatsoever as long as temp stays below 50c. From optimas 4.2L spec sheel. They recommend charging fast in cyclic operations in this way.

The BULK phase on that charger is 14.7+ But thats fine as it wont actually achieve that as its only "TRYING" to reach 14.7 with its rated amps. It just ensures fast charging. (max amps for longer!) As the real battery voltage actually gets to this voltage it drops to a safe gas free current and voltage level. Absorbtion. This is just where the full rated amps are no longer needed and its voltage controlled instead.

So that algo is perfect for AGM but will damage a GEL battery.
A 14.4 charge voltage will also work on AGM but will actually just take longer. Considerably longer actually. As it drops the amps back earlier.

PB Batteres dont "gas" unless you exeed 14.4V or (14.7V AGM). And only then when the charge is complete or almost so. Actually thats not quite true, but they do it less so when not fully charged even if the voltage is held a little high. Thats why the charge voltage can be higher during the bulk phase. It will be perfect. If a touch slow. I use 30 amp because I cant find a bifgger one cheap! That power supply does 40 Athough. 200 A would be perfect!

When current falls to less than say 2 amp its good to go back into the competition - the final 10 percent takes ages. When it drops to say 200ma then its charged 100 percent. (or 5 hours at absorbtion or 14,4 / 14.7v whichever comes first) Thats all there is to a fancy 3 stage cherger. And the third stage is float.

Float needs to be 13.4to 13.6v (optima) or 13.2 very long term so they dont dry out. The only reason you cant actually charge at that level over a long period is that the cells wont get a controlled overcharge to equalise them.

I know way too much about charging and batteries...

[Burgerman]

Some more info as to why battery manufacturers recommend 5 and 8 amp chargers... Because the battery uses some clever technology to recombine the oxygen and hydrogen that is given off when a battery is charged. (or discharged) Its ability is limited but can cope ok at any charge rate or discharge rate provided the battery isnt overcharged. So a cheap charger or taper charger that will trickle charge your battery at low power after its charged can over volt the battery. This can still be controlled by the recombinant technology. Unless you charge at a high rate above the recommebded 14.4. Which bigger cheap nasty chargers may do. With modern logic controlled chargers its not an issue.

[JoeC]

Thanks for the explanation. I'll get one on order.

It's always baffled me why Optima's people tell me over the phone, "The maximum current allowed with a battery charger is ten amps." No explanation, no reason why it's OK to do 100+ amps with an alternator, no idea how a battery charger could be somehow worse for the battery at a lower current!

[Burgerman]

Its because the people you are talking to are not very bright! They learn stuff parrot fashion but dont really get it.

http://www.optimabattery.co.uk/pdf/6p_E ... _RTYT_.pdf from another of my sites....

I copied and pasted the charging instructions from optimas own pdf file here: Note recomendations for cyclic use. No, not an 8 amp charger NO LIMITS! Much of this applies to all AGMs and as long as you dont go mad on the voltage also Gel batteries.

CHARGING INFORMATION
Alternator
13,8 to 15,0 volts.

Float Charge
13,2 to 13,8 volts, 1 amp maximum current.

Rapid Recharge (Constant voltage charger)
Maximum voltage 15,6 volts. No current limit as long as temperature
remains below 51 degrees C. Charge until current drops
below 1 amp. Recharge time will vary according to temperature and charger
characteristics. When using Constant Voltage chargers, amperage
will taper down to as the battery becomes recharged. When
amperage drops below 1 amp, the battery will be close to a full
state of charge.

Cyclic application or series string applications (CV/CC) only:
Constant Voltage with Constant Current finish: 14,7 volts, temperature
< 51degrees C, no current limits. When current falls
below 1 amp, finish with 2 amp constant current 1 hour.

For additional charging information contact your
Authorized OPTIMA dealer.


WHICH IS ME...

[Burgerman]

Alternator recomendations are 13.8 (trucks and things that do long distances regularly. Boats, Generators, Plant etc.
Alternator up to 15v (14.7 Perfect, 14.4 is normal) for short stop / start town use.

Use 15v on a truck and you dry out the battery early.
Use 13.8 on a car thats used for winter shopping trips and it will not get charged properly. And may suffer sulphation or go flat.

Float charge 13.2 takes forever but can be safely used forever. 13.8 FLOAT will charge "quickly" but long term will cost electrolyte.

[JoeC]

Just ordered one! Found a cheaper source so only $265 shipped, though I still need to buy the parts to build new battery cables. We will have no more worries of whether or not we'll get home after a long day of practice!

[Burgerman]

All this info directly from the manufacturers of the batteries saying we not only can charge at huge currents but we should because its better, faster and the recommended method. Optima advise you to charge at unlimeted amps for cyclic use. Hawker Odyssey sell their own 50 amp charger for their tinyest deep cycle batteries upwards! Ten times smaller than a powerchair battery and a 50 amp charger...

Then we get the idiot manufacturers saying we should use a tiny 5 amp or 8 amp charger! For 30 years! I keep reading this bull on all kinds of sites including that WCJ site where he obviously doesent get chargers or batteries at all! Makes me laugh when I read his hopeless advice...

So until the manufacturers move on, and stop copying each other, using the same industry standardised components, and actually learn some stuff then we are stuck! Well everybody else is. I do my own thing! One or two others do too. But most people just suffer. I dont just mean chargers/batteries I mean all of what they do. They are so "stuck" in the dark with their design by comittee systems that there is no progress that I can see in the last 15 years. Nothing substantial. I mean I cant even buy a decent powerchair! I have to build my own in a bedroom.

Thats why I put up my site. To try and shake them up a bit! This battery issue alone causes people that really use a chair grief! And I keep reading rubbish about how you cant interupt a "multi stage charger" by people like the wcj who clearly has no clue how they work. Or how you should "only charge once daily if possible" etc. All completely wrong!

If you charged 20 times a day, kept the discharge level minimal, every time you could your batteries would last as long as they do in a car! 5 to 8 years. But I give up, because the sheep, the "industry EXPERTS" just do not get it!

[JoeC]

To be clear, the word "wheelchair" never entered the conversation when I was asking Optima USA what current I could use with a battery charger- so go figure! Maybe the phone rep I spoke with was intentionally giving bad information.

Regardless, I know of one street-legal vehicle out there that routinely charges these batteries at over 20 amps from the wall:

http://www.corbinsparrow.com/

Also, the Dynamic DX2 is rated by the manufacturer to take 15 amps at the charger port, last time I checked. That's a step in the right direction.

[Burgerman]

That car looks fun! Needs a 450bhp turbo drag bike engine in it though. Shame there are no tech details. Well you will be pleased at how fast your 25 amp charger works! At least to the 90 percent level with good batteries. You only need more amps for very depleted batteries. So charge times will be only very slightly effected compared to mine.

The anderson connectors are the 50 amp ones. You may as well buy a bucket full as I did. Youwill finish up using them for everything and your slow chargers too. And you may as well add some 12v ones for charging from a car or jump starting the car while you are at it! I finished up with them on everything from an electric lawnmower, to my van, inverters, helicopters lithium charger etc. And an extension lead for charging chair from van...

P and G say 12 amps. But those XLR microphone type connectors wear and get loose and go high resistance and get hot at 7 amps usually! So its not a brilliant arangement. Again its industry wide. Nobody thinks.

[Burgerman]

Just recieved two things.

email from a chinese company who sell 5, 8, 12, up to 80 amp chargers for 12, 24, upwards batteries.

They say that the only real reasons that they recomend sall 8 amp chargers for powerchair use is because at that power level they can build them fan and noise free.

And that charging with a 30 amp or bigger charger is no problem for the batteries although due to electrolyte stratification between the plate a gel battery will not be as fully charged as if its charged very slowly. Which we already know. MK batteries are typically 5 percent less "full" directly after a fast charge. AGM batteries are less effected because the acid is more mobile. And cost. Although both will catch up during the float stage later on if a slightly high float level above 13.4 per battery is used. So overnight it results in the same charge.

And an almost exact same answer from the MK REP... So there it is. Money, and fan noise. And because its traditional... But my 8 amp chargers all have fans! And the big fan in my 30 amp charger is quieter. Err...

Chinese companies site http://www.epowerfirst.com/ and http://www.epowerfirst.com/products.asp Looking at buying batches of AGM 30 amp chargers with this DIN 41773 AGM Charging algo (measured on 8 amp version below) switchable to Gel and also 12/24v. Would supply complete with anderson connectors and cabled etc as a retrofit for users with a life that actually use their chairs/scooters!

Ist part of graph shows discharge under load down to 21v... Then an ideal charge algo on a 70 ah AGM battery. Gel is similar but lower peak voltages.

!cid_00b601cabc2a$766acec0$7c00a8c0@powerfir92f5b4.jpg (79.67 KiB) Viewed 6688 times

Note that the difference in voltage between 8 amp load and 8 amp charge is huge and allows you to see the batteries internal resistance. This is a 16 amp change and 3.5 volts! Imagine that at 100 amps. Use ohms law to see how bad a discharged battery is! And why we use optimas/odyssey batteries...

[JoeC]

For anybody in the US who's interested, I just received my Iota DLS-27-75 from RVFunproducts.com. I had never heard of that website before, but they had the best price I could find on this product.

http://www.rvfunproducts.com/iota-dls27 ... -2809.html

It arrived reasonably quickly on free shipping, package was undamaged but lacked the kind of styrofoam shell that gives me a warm feeling of confidence. The charger includes a power cord, but not battery cable. I will be installing a connector for the soccer chair this week, and will report back if anything eventful occurs.

[Burgerman]

That chargers specs say that under load its only 27v ?

It will still charge fine, but will soon "drop off" the high amp charge rate and go to a lower amp charge rate as the battery voltage gets pulled up to 27v.

It will therefore take quite a bit longer than my power supply or my 30 amp charger (or your cars alternator) as these just hold 28.8v "solid" as long as they can make enough amps to do so. So higher amps for considerably longer as it charges.

If you see what I mean? But it might have some adjustability inside.

Your clamp meter will tell you this happens when you charge.

It will start (with a deadish battery) at 25 amps, and as soon as it sees 27v after a few mins amps will start to drop off and voltage will rise. Still be hugely faster than the stock 8 amp charger though. At least at the first part of the charge.

___________________________________________
Actually I just read it again.
It seems that its not a multi stage charger? It is just a fixed voltage (float charge/voltage) device. I think it is a power supply with the voltage set low enough so that it can float charge 24v batteries or renmain connected as maintainance. If thats the case it will take a long time to charge. I think it maybe has no charge algo (like the graph earlier) at all.

Thats still not a problem, if you set its voltage to 28.8 max (good multi meter!) rather than 27.2.

You then stop charging when you want to. Less than 3 amps would be about about 90 percent charged. Less than .5 amps would be 99 percent charged.


At 27.2v it will take 6 to 8 hours for a full charge or more. And it will not equalise cells. Which is important in cyclic operations rather than a boat or RV or starter battery.

I suspect its designed to plug in at a site so you can run everything all night and keep your RVs batteries topped up at the same time with up to 25 amp on demand.

[JoeC]

Thought I mentioned- I got the IQ4 upgrade, with the three stage charging algorithm. Manufacturer details here: http://www.iotaengineering.com/iq.htm

29.52 volts for the bulk charge, so it should stay at or near 25 amps for a good length of time. I still haven't figured out what's wrong with the upper range of my Tenma clamp meter, but I do think I still trust the 0-40 amp range. I will monitor closely with that and my infrared thermometer.

[Burgerman]

Yes you did now I recall!

But that link didnt show that!

Still for others looking to buy one in the US this will explain the difference! Let us know how it works! You will be surprised how fast it is.

No need to worry about heat. My Odyssey ones only get barely warm to the touch at 100 amps charge from flat! Gels may be different. And they can get to a thermal runaway situation. But I charge those too at 30 amps without any noticible warmth. (Other than the battery cables)

It also says max power output is 675 watts? 28.8 x 25 amps = 720 watts? I suspect their maths is crap or they ignored the add on proper charge gadget!

Let us know how it goes. And any downsides, although I suspect there are zero.

[Lord Chatterley]

I may be overlooking some obvious obstacle, but is there any reason why powerchairs should not have a built-in onboard charger, so the only thing you would need to do is unwind a cable and plug directly into the mains?

[JoeC]

They do come standard on some chairs and scooters, but usually when I see them they are only 2 or 4 amp chargers. Cost is probably the reason why they're not installed standard. You could make a fast charger that is durable, compact, environmentally sealed, but it would cost more than the chargers they ship with the chairs now.