Forum Discussion

Explorer

May 21, 2014

This Is Plan For My Own Battery CHARGER

AMMO CAN
BATTERY CHARGING SYSTEM

Switch type power supplies have made transformer battery chargers obsolete. The new power supplies are so small, and less heat producing it is possible to stuff a lot of power supplies, DC to DC converters, fans, timers, switches and voltage adjusting rheostats into a War Surplus 40 mm ammunition box. Heavy gauge steel.

I decided to produce a charger with a maximum charging potential of 60 amperes. The unit has a “do-all” timer. A 12-hour spring wound timer which is bulletproof, and easy and fast to operate. But the timer does not control one feature – a battery maintenance charger which is set to 13.4 volts and has a potential up to 10-amperes of charging at that voltage. When charging, or equalization is terminated the Ammo Can automatically defaults to battery maintenance charging.

A good battery charger has an equalization system built-in, that observes the Battery Council International (BCI) recommendation for constant amperage charging at exactly 5% of total battery ampere hour capacity. The Ammo Can Charger, provides constant 5 amperes charge rate limited to 16 volts, for group 24 and 27 batteries and another system to provide 11 amperes voltage limited to 8 volts for a single GC 220 golf car battery. The functions are switch selectable and time controlled with the 12-hour timer. A surplus rainproof generator control panel with hinged transparent Lexan lid was modified to allow placement of the 12-hour timer, switches, and digital voltmeters (2) and ammeter.

How Is This Accomplished?

2-33 ampere Meanwell power supplies are utilized. The power supplies are isolated by a Shottky 300 ampere rectifier pair. One 200-watt DC-to-DC boost converter feeds a constant amperage control circuit for 12-volt equalization. One buck DC to DC converter feeds a 2nd constant amperage control circuit. The boost converter is set at 16.0 volts, the buck converter is set at 8.0 volts, the 1st amperage control circuit (for 12 volt batteries) is limited to 5.0 amperes, constant – the 2nd amperage control is placed after the buck converter and limits 8 volt current to 11 amperes.

A shunt monitors amperage as voltage enters the positive battery charging cable. Voltage is monitored at this point as well. Both measuring devices are not closed loop but rather fed 5.0 volts from yet another power supply (a TO-220 regulator on a heat sink). The meters are fed by the battery maintenance charging circuit.

A pair of 50 mm ball-bearing 33 db 12-volt fans control ventilation. One fan takes air from exterior, the second fan takes air from the interior of the Ammo Can case.

Control is extremely simple. The Intermatic spring-wound 12-hour timer, is also the on-off switch except for the maintenance charger. 1 on/on switch chooses one or both power supplies. Two 50-amp power switch controls output to both of the power supplies. When power is switched off at both 50-amp switches (they are ganged like a house 240 volt circuit breaker), it serves as a control signal to a SPDT Tyco relay. The relay switches off. Remember, the main power is isolated by the Shottky rectifiers. Power can not “feed back”. The only power circuit running through the Tyco relay is through the NO contacts – please do not confuse this with the relay's control circuit. When power to the relay coil stops, the relay switches to the NC contacts. The power now flowing through the NC contacts is the main power feed for both buck and boost DC to DC converters. Another DPDT on/on switch chooses boost for 12-volt equalization or buck for 6-volt equalization. The current limiting devices follow in the circuit after the buck and boost converters so no selection or control is warranted. Both voltages and current are controlled.

It may sound complicated but this is how the Ammo Can Charger operates...

For regular charging select timer spring control up to 12-hours of operation, after insuring both 50-amp rated switches are switched to “on” to allow full 60-amp charging potential. The digital voltmeter and ammeter allow precise resolution of event as they are occurring.

Battery equalization. Select timer spring control up to 12-hours of operation. Switch off both 50-amp rated toggle switches, select on/on switch to direct power to either the 16 volt or 8 volt equalization circuit. Remember, equalization current is constant meaning it is controlled appropriately. The digital voltmeter and ammeter allow precise resolution of event values as they are occurring

Protection circuits. One pushbutton 15-ampere breaker. The equalization circuits, both of them are protected by the Tyco relay against feedback voltage when either of the main Meanwell power supplies are in operation. The Shottky rectifiers isolate and protect the Meanwell power supplies. The maintenance charger is isolated/protected by it's own Shottky rectifier in it's output circuit.

In the event of a power failure, the spring-wound timer continues to count down and shuts off in a normal manner.

The battery maintenance charger is protected by it's own Shottky rectifier, which is rated at 200% of maintenance charger maximum potential.

To clarify, when the Ammo Can charger is plugged into AC power, the maintenance charger is working. No switches control the maintenance charger. The maintenance charger output power however does pass through the ammeter shunt. The maintenance charger also powers the 5 volt power supply, which powers the ammeter and voltmeter. When the meters are lit the Ammo Can charger has power. Plug in the Ammo Can charger and the meters light up. You are wondering about the fans. 12-volt power from the maintenance charger powers both fans.

The Ammo Can charger has a maximum draw potential of one or two microamperes if it is connected to a battery, and AC power is interrupted. Therefore feedback “power bleed” is infinitesimal.

The Ammo Can Charger Is Not Financially Feasible To Manucture For Retail Sale

34 Replies

2012Coleman
Explorer II
May 30, 2014
I just bought a couple of hamsters and squirrel cages...
NinerBikes
Explorer
May 30, 2014
MexicanWanderer, how is your build coming along on this? Parts all arrive yet?
NinerBikes
Explorer
May 25, 2014
MEXICOWANDERER wrote:
Try connecting a total of 80 uf RUN capacitors to the power inlet of the MeanWell.

You'll find a great selection of RUN capacitors at

surplussaleales.com

Mex, I have no idea what an 80 micro farad R.U.N. Capacitor does.
NinerBikes
Explorer
May 23, 2014
MEXICOWANDERER wrote:
NinerBikes, observation is right on the money. But the absolute fastest charge protocol is not a 100% of the time regimen. The power supplies can be tweaked with the adjustable potentiometers. I am going to find a savvy tech with excellent vision and rock steady younger hands and replace these pots with 2-watt 3 turn 2K pots that have shafts that can have a knob with pointer screwed on.

Scenario
Hotel room. BiPAP and LED reading light. Battery. Lights go out for 4 hours at night. Charger will be plugged in, maintenance charge going. Lights come back on for a hour or so. Power supplies are set at full acceptance voltage but rational for the circumstances 14.4 volts. The timer has to be cranked to 12-hours, I think I can remember to do that before switching off the reading light. The BiPAP draws more then 4 amperes, the reading light an amp or two. The Fantastic Fan around three amperes.

14.4 volts is RV alternator charging regulator set point. If you have an issue with a 14.4 volt setting go argue with your motorhome or tow pickup's charging system.

A higher than 14.4 volt setting is for TOP CHARGING. This is where the 2 ampere 3 turn pots come in.

Remember and this is IMPORTANT.........With a power supply, you set the VOLTAGE without being connected to a battery. With built-in gauges, this takes what (?) 2.7 seconds?

They make current limiting modules that re adjustable. They cannot handle a lot of current, but they can handle ENOUGH amperage to satisfy equalization. Constant current until three or four tenths less than 16.0 volts. Then current tapers down because charge acceptance become very limited. Natural electro-chemical reaction.

This unit MAY penalize battery life by 5% or most probably <5%

Most of the Mexican fishermen go out at night and use 50W incandescent lighting. Their 20-minute run back to the beach does not recharge their group 27 battery. Jesus is going to charge them 30 pesos, and it's a 100 meter walk from their lancha to the enramada. 300 pesos a day is better than a kick in the butt.

So, is Jesus your new handle, and what's 300 pesos in $ US for a recharge? You run your genny down there on a dolly? No habla Espanol.
MEXICOWANDERER
Explorer
May 23, 2014
NinerBikes, observation is right on the money. But the absolute fastest charge protocol is not a 100% of the time regimen. The power supplies can be tweaked with the adjustable potentiometers. I am going to find a savvy tech with excellent vision and rock steady younger hands and replace these pots with 2-watt 3 turn 2K pots that have shafts that can have a knob with pointer screwed on.

Scenario
Hotel room. BiPAP and LED reading light. Battery. Lights go out for 4 hours at night. Charger will be plugged in, maintenance charge going. Lights come back on for a hour or so. Power supplies are set at full acceptance voltage but rational for the circumstances 14.4 volts. The timer has to be cranked to 12-hours, I think I can remember to do that before switching off the reading light. The BiPAP draws more then 4 amperes, the reading light an amp or two. The Fantastic Fan around three amperes.

14.4 volts is RV alternator charging regulator set point. If you have an issue with a 14.4 volt setting go argue with your motorhome or tow pickup's charging system.

A higher than 14.4 volt setting is for TOP CHARGING. This is where the 2 ampere 3 turn pots come in.

Remember and this is IMPORTANT.........With a power supply, you set the VOLTAGE without being connected to a battery. With built-in gauges, this takes what (?) 2.7 seconds?

They make current limiting modules that re adjustable. They cannot handle a lot of current, but they can handle ENOUGH amperage to satisfy equalization. Constant current until three or four tenths less than 16.0 volts. Then current tapers down because charge acceptance become very limited. Natural electro-chemical reaction.

This unit MAY penalize battery life by 5% or most probably <5%

Most of the Mexican fishermen go out at night and use 50W incandescent lighting. Their 20-minute run back to the beach does not recharge their group 27 battery. Jesus is going to charge them 30 pesos, and it's a 100 meter walk from their lancha to the enramada. 300 pesos a day is better than a kick in the butt.
westend
Explorer
May 23, 2014
niner bikes wrote:
The adjustment on the pot with a phillips is kind of touchy and sensitive

That's when you need to terminate the pot circuit into something like this CCCP product. :B

I haven't found a use for the big attenuator, yet, but I'm sure something will pop up.
NinerBikes
Explorer
May 23, 2014
BFL13 wrote:
Don't need any lessons in how to reduce gen time by using an higher charging rate--see my ugly graph how that works in real life. Meanwhile---

I still don't understand how you can equalize at a constant amps at a constant voltage like I think was claimed.

When the batts are full and you then do your overcharge, with my charger at constant 15.7v, the amps still taper. How the heck can you keep the amps at say 5 amps at 15.5 volts????

When Mex says "max acceptance rate" at whatever voltage they are held at, to me that means the max acceptance rate tapers as battery SOC rises. SOC rises even higher than 'so-called' "full" because you are doing an overcharge. Maybe all the extra goes off as heat so the amps stay the same? I have no idea. My charger when doing an "equalize" at constant 15.7 volts gets it done but amps taper down to nothing during that time.

Does this gizmo Mex is building not have the amps tapering? How can that happen?

The amps taper. That is controlled by the size of the battery bank. You can't give it amps that the basic chemical reaction won't take. It just won't flow the current. Any excess goes into off gassing and making hydrogen and oxygen out of water, plus some bonus sulfur smells that will eat up and corrode your copper electrical connections if poorly insulated. The blue/green stuff on you copper wire might be copper sulfate.

You only use the amps it takes to do the complete chemical reaction... to get what ever sulfur was on the plates, completely into H2SO4, or sulfuric acid, diluted in water. The more acid in the water, the denser the solution, the higher the specific gravity, up to a limit, of course. Beyond that, I assume you are roasting the plates.

I can't speak for equalizing... I don't have a booster on mine... I could adjust to a full 15.6V, but I leave mine at I think 14.99 to 15.04V, and shut down before the final whatever %, and let the solar panel handle the rest to get it to 100% @ 15V and with a max of 6.6 amps from my 120 watt solar panel. In the end, the solar panel will end up nursing it the last 3 to 5% of the top off charge, in my situation.

In Mex's case, shortened battery life is cheaper than gas. In my case, kind of a non issue, I have to get groceries every 5 -7 days in town anyways, buy another gallon or two of gas for the little Honda... and the Touareg TDI gets 33 to 35 MPG running around without the travel trailer. Maybe do laundry too while there. Today I ordered a 4 digit volt meter... it's going on the Mega Watt, so I can always see where I am at voltage wise on the adjustment. The adjustment on the pot with a phillips is kind of touchy and sensitive.
westend
Explorer
May 23, 2014
BFL13 wrote:
Does this gizmo Mex is building not have the amps tapering? How can that happen?
He is using a buck and a boost transformer with regulation circuits. The Ammo Can differs from a conventional charger because the voltage and amperage can be set at a particular level and it holds that setting. He has three settings if I understand the design correctly.
Maybe the Ammo Can II will have an autoformer built in to control voltage. :B
BFL13
Explorer II
May 23, 2014
Don't need any lessons in how to reduce gen time by using an higher charging rate--see my ugly graph how that works in real life. Meanwhile---

I still don't understand how you can equalize at a constant amps at a constant voltage like I think was claimed.

When the batts are full and you then do your overcharge, with my charger at constant 15.7v, the amps still taper. How the heck can you keep the amps at say 5 amps at 15.5 volts????

When Mex says "max acceptance rate" at whatever voltage they are held at, to me that means the max acceptance rate tapers as battery SOC rises. SOC rises even higher than 'so-called' "full" because you are doing an overcharge. Maybe all the extra goes off as heat so the amps stay the same? I have no idea. My charger when doing an "equalize" at constant 15.7 volts gets it done but amps taper down to nothing during that time.

Does this gizmo Mex is building not have the amps tapering? How can that happen?
NinerBikes
Explorer
May 22, 2014
Laymen's terms.

In a rush, want to minimize operating time of generator while charging? For a 12V battery, set your voltage on this power supply unit at 15.0V.

Want to save your battery life? Set it at 14.4V and bulk charge it.

Shut down when you reach a charge rate of 8 to 6 amps. 8 amps for 220 ah pair of 6v GC2's, and 6 amps if you are charging a T1275 12V. The T-125 takes 15.0V quite nicely, it does a good job of keeping your Specific Gravity from sagging too much, as near as I can tell, and the battery acid stays nice and stirred up also.