Doomer Lead-Acid Charger

[mousewizard]

Background: I'm a survivalist. One of my post-collapse businesses will be bartering and charging batteries. Since this is a post-collapse scenario, the objective is to be able to work with a set of solar panels, and not use 120VAC. Yes, you can have inverters to do stuff (and I have multiples on hand), but the most efficient, least-loss approach is DC to DC, and eliminating the inverter takes a really complex component out of the MTBF calculations.

I've got AA/AAA charging covered (multiple Maha MH-C9000s on a RigRunner hooked to my solar system) but need to address Lead Acid. In a post-collapse scenario a lot of UPS units are going to get scavenged, so people will be bringing these batteries in for charging, not to mention car batteries.

Now, I could simply use a solar charge controller to do the job, but I'm wondering about the four-step algorithm for optimal SLA charging. Is there a SLA/AGM charger out there that uses the standard 4-step algorithm as described by Deltran, but runs on DC? I'm thinking I could set up a 24v battery bank to run such a charger (would enable charging overnight), but is there a charger that can do this out there? All the ones I can find take household current.

Has anyone taken a Deltran unit apart and figured out what the internal power supply is producing?

Or would I be better off using a solar charge controller and just charging during the daytime?

 

[Shadowww]

No idea about 4-stage chargers, but hobby chargers are doing quite good job at charging Pb batteries. Cheaper ones only support 2V - 20V ones, more expensive ones support up to 36V lead-acids.
They also have very wide input voltage range (10V - 18V for cheaper ones, 5V - 38V for more expensive ones), so I guess you can run one directly off a solar panel.

 

[USSR]

if u r good at circuit making there are dedicated chips that will charge using 4 streps..such ics are made by ti ,, and many others...

or u can google one prebuilt ..

 

[czAtlantis]

Charging lead-acid is really easy - for UPS batteries there are 2 possible recommended voltage threshold, you just charge CCCV(0.1C) just like li-ions.
Standby mode: 13,8V
Cycle mode 14,4V
Standby mode means the battery is connected to this voltage for longer periods (like in UPS, security systems...)
Cycle mode means the battery is cycled and charged "just for charging" (forklift, flashlights)

Advantages of standby mode is that battery can be connected for infinite time but it will reach 100% charge in long time (week or so). On the other hand when charging in cycle mode it will absorb energy more quickly but with more wear (at this voltage the plates suffer as well some water is changed to hydrogen and oxygen). I always charge at standby voltage, it will eventually charge to 100%.

But the main problem with lead-acid will be sulfatation - in your scenario those UPS batteries will be discharged for long time and damaged. In some cases it is possible to resurrect these batteries just connecting them to standby voltage for longer time but sometimes it wont help

 

[mousewizard]

No idea about 4-stage chargers, but hobby chargers are doing quite good job at charging Pb batteries. Cheaper ones only support 2V - 20V ones, more expensive ones support up to 36V lead-acids.
They also have very wide input voltage range (10V - 18V for cheaper ones, 5V - 38V for more expensive ones), so I guess you can run one directly off a solar panel.

I had looked at hobby chargers but they appear to focus mostly on really fast charging (high amperage) for Lithium-whatever packs, looks like for the RC crowd. So the Pb charging features, while programmable, are a really small subset of what I'd be paying hundreds for. Unfortunately, dedicated SLA/AGM chargers seem to sit on the other side of the scale, much simpler, but all with AC inputs.

Most of the hobby chargers seem to be focused on the high end, rapid-charge, balanced-charge side. However, they're really good, DC-Powered, regulated power supplies where you can set the current and voltage and have it hold. Ideal for Pb charging, but good grief are they expensive! Remember, as a survivalist, I have to buy at least two (in survival two is one and one is none), so that gets pricey fast.

So my question is: Is there a lower cost hobby charger out there that has a good reputation, doesn't have all the bells and whistles, but will still do the job?

 

[mousewizard]

if u r good at circuit making there are dedicated chips that will charge using 4 streps..such ics are made by ti ,, and many others...

or u can google one prebuilt ..

That's definitely a possibility. Do you have the TI chip number handy? I haven't searched TI catalogs in a while.

 

[mousewizard]

Charging lead-acid is really easy - for UPS batteries there are 2 possible recommended voltage threshold, you just charge CCCV(0.1C) just like li-ions.
Standby mode: 13,8V
Cycle mode 14,4V
Standby mode means the battery is connected to this voltage for longer periods (like in UPS, security systems...)
Cycle mode means the battery is cycled and charged "just for charging" (forklift, flashlights)

Advantages of standby mode is that battery can be connected for infinite time but it will reach 100% charge in long time (week or so). On the other hand when charging in cycle mode it will absorb energy more quickly but with more wear (at this voltage the plates suffer as well some water is changed to hydrogen and oxygen). I always charge at standby voltage, it will eventually charge to 100%.

But the main problem with lead-acid will be sulfatation - in your scenario those UPS batteries will be discharged for long time and damaged. In some cases it is possible to resurrect these batteries just connecting them to standby voltage for longer time but sometimes it wont help

I understand that a lot of batteries brought in will be essentially dead. That's where a good testing protocol comes in. I see there are really sophisticated battery testers out there, like the ACT or BK, but those are really expensive, complex instruments designed to be run by techs, in the field, and in a hurry. All that adds up to significant bucks, on the order of $300-$400 each. Since I'd have to buy at least two, I'm interested in finding a simpler, cheaper way to do it. I took a look at Steve Duncan's approach to discharge testing and wonder if that might just be the way to go? It's simple, but takes a lot of time. That seems to be the trade-off; time vs. simplicity.

 

[jeffosborne]

Hi mousewizard! Hobby chargers are not necessarily expensive. I have owned this one for a couple of years with excellent results on all types of batteries, including lead acid. Up to 6 amp charging current from an input range of 11-17 volts. From hobbyking.com, search for product id ACC6, the Turnigy Accucell 6, $24.07 from a US warehouse

 

[Colonel Sanders]

+1 :thumbsup: Unless you need alot of power (like me) then a good hobby charger is not expensive and should prove very effective. I have an el cheapo hobby charger very similar to the Accucell 6 that does a fine job with Pb batteries (as well as just about anything else.) For more (MUCH MORE!) power I also have an Icharger 3010b which is very cheap for what it can do.

Hi mousewizard! Hobby chargers are not necessarily expensive. I have owned this one for a couple of years with excellent results on all types of batteries, including lead acid. Up to 6 amp charging current from an input range of 11-17 volts. From hobbyking.com, search for product id ACC6, the Turnigy Accucell 6, $24.07 from a US warehouse

 

[czAtlantis]

Well I would invest in more expensive charger because those cheaper ones can't change voltage thresholds for charging! It just gives you lead acid=14,7V, li-ion=4,2etc...I have icharger and I can change those voltages up and down!

EDIT: another AWESOME function my iCharger has is regenerative discharge...It means when you are cycling/testing (measuring capacity..) some cell when it discharges this cell it RECHARGES your source. So when you have source from car battery and you are discharging (even single cell) li-ion cell it draws energy from liion and stores it back to lead-acid! I can imagine this being crucial function in solar-powered emergency!

 

[mousewizard]

Well I would invest in more expensive charger because those cheaper ones can't change voltage thresholds for charging! It just gives you lead acid=14,7V, li-ion=4,2etc...I have icharger and I can change those voltages up and down!

EDIT: another AWESOME function my iCharger has is regenerative discharge...It means when you are cycling/testing (measuring capacity..) some cell when it discharges this cell it RECHARGES your source. So when you have source from car battery and you are discharging (even single cell) li-ion cell it draws energy from liion and stores it back to lead-acid! I can imagine this being crucial function in solar-powered emergency!

The iCharger sounds good, and at $89 for the 106b, I can have multiples running at the same time for multiple batteries.

I don't need a lot of wattage, because most UPS's scale to larger by adding more 6v or 12v batteries in series or parallel to get that larger capacity. They prefer to go up in voltage as capacity goes up, so you can wind up with a 48v system based on 8 6v 12AH batteries. So a hundred watt charging capacity should do the trick when charging batteries one by one.

Anyone else have recommendations?

 

[USSR]

That's definitely a possibility. Do you have the TI chip number handy? I haven't searched TI catalogs in a while.

all ti products can be easily searched from this link just click on desired application..

http://www.ti.com/general/docs/prod.tsp?DCMP=TIHeaderTracking&HQS=Other+OT+hdr_p_products

select the appropriate condoitions/paramerters..
http://focus.ti.com/paramsearch/doc...log&familyId=394&uiTemplateId=NODE_STRY_PGE_T

here are few i would recomend
UC2906 - Linear Lead-Acid Battery Charger
UC2909 - Switch-mode Lead-Acid Battery Charger with Differential Current Sense
UC3906 - Linear Lead-Acid Battery Charger

linear one are easy to implement

Battery Charge Management Selection Tool // clocl om the more info tab..as well
http://focus.ti.com/en/download/aap/selectiontools/battery-chargers/tool.htm

 

[mousewizard]

Thanks, USSR! That'll get me started down the path.

 

[mousewizard]

I got two iCharger 106b hobby chargers in and bench tested them. I must say I'm very impressed. They use a buck-boost dc-dc converter so they can put out whatever's needed while using a normal 12V input source. That's how they get 14.2 volts out when all that's coming in is 12V from my bench power supply. Very nice units and reasonably priced. I set up my bench laptop with the LabView software and built a pretty snazzy looking rig with dancing graphs while charging a SLA battery. They have limited discharge capability (fine for hobby-size batteries) but I'll need to build a light-bulb based discharge load to cycle and test larger batteries.

 

[HKJ]

The 106B can do discharge at a fairly large current (7A, 250 watt) if you use regenerative discharge. The larger iChargers can do even more, up to 30A and 1200Watt.

 

[czAtlantis]

Just small note - when using regenerative discharge reported capacity is slightly different compared to standard discharge...at least when I tried with my 206B discharging at 1A single liion cell it was around 10% off.
Maybe with higher currents it won't matter.

Also another problem I discovered - this charger doesn't work well when input voltage is not 100% stabilized. I have 13.8V system at my room I use for powering my 12V devices like DSL modem, router, switch and also Maha C9000. And when Maha pulse charges the voltage fluctuates (0.1V max). But this icharger can't respond to these fluctuations well and output current fluctuates as well! Problem is when battery is reaching to 100% charge and termination current is set to 0.1A, real current is for example at the moment 0.3A but when there is fluctuation in input voltage it easily drops to 0.08A and charger terminates charging as "fully charged". This is not really big issue if you are just charging few cells but if you are testing cells and you want really steady results you should be aware of this. This also applies to regenerative discharge! Using normal discharge I didn't observe this behaviour.

 

[mousewizard]

The 106B can do discharge at a fairly large current (7A, 250 watt) if you use regenerative discharge. The larger iChargers can do even more, up to 30A and 1200Watt.

I'll be sticking with the 106B as a standard model. The others can accept higher input voltages than my system will ever produce, and I won't be doing rapid charges on 750W LiFePO batteries. However, I will need discharge capabilities beyond 7A, hence the need for a home-built load. Or, I might spring for something like the CBA III Pro. It'll do the job for virtually anything I might encounter like scavenged UPS batteries and car batteries. Solar system batteries like Trojan L16s are a different matter. Don't expect to see hardly any of those, so don't need to prep for them either.

 

[mousewizard]

Just small note - when using regenerative discharge reported capacity is slightly different compared to standard discharge...at least when I tried with my 206B discharging at 1A single liion cell it was around 10% off...! Using normal discharge I didn't observe this behaviour.

Thanks for the info. I've added this to the iCharger section in my notebook.

 

[SemiMan]

I think you will find that most AGM battery suppliers, the type of battery in a UPS, suggest a 3 stage charge.

If you are thinking end of the world scenario, I would look at a Morningstar Charge Controller, either a PWM version or MPPT. MPPT are more complex, but can better use the panel and handle panel/battery voltage differences. Unless you have a lot of solar panel, realistically most 3 stage chargers for solar are really 2 stage because they don't have enough current output for a true bulk stage so in essence they are constant current/constant voltage chargers.

Some of the Morningstar chargers can do an equalization charge as well, so in essence they can do a 4 stage.

However, you should only do an equalization charge on certain types of batteries, i.e. most AGM, if they really need it, i.e. they have been sitting in an extended state of partial discharge. If they are being regularly charged/discharged they don't need it. Equalization will shorten the life of the AGM battery if not needed as it will cause gas discharge.

Semiman

 

[mousewizard]

Yeah, I use Morningstar on my solar system. I suppose I could set up a small Morningstar controller and feed it from a hobby charger to simulate 16V input from a fully illuminated panel array. The problem is the Morningstars decide when they'll do equalization, and I'm not sure whether I can gain some control over that.