MTFCA Forum

I wonder if a 12v 10 or 12 AH lithium wouldn't be money better spent do to longevity?

Unfortunately I'm not familiar with magneto chargers. Depends on the voltage you can get from the magneto charger. Can you limit the charging to 14 volts max? and is there any type of regulator to stop charging the battery? 18 amp hour is pretty good, but the higher the amp hour rating the better. If that is the biggest that will fit it will have to do.

I run a 'standard' battery to power the TT. I only charge it at night with a regular charger (no charger in the TT), more than enough power to keep the TT running all day.

I realise Steve will need to charge on the road, as his camping style usually includes car parks and the like (actually it appeals as an adventure!)

Steve,

The battery capacity should be adequate for your stated use, however both John and Pat raise valid points.

• It will assist the life of your battery considerably if it's correctly charged. Some of the magneto charger circuits I've seen don't have a regulator and will continue to supply current to a battery beyond the typical max voltage you'd usually want to use. While the current isn't high (so it's unlikely to result in a fire) it's not good practice, thus it'd be good to check your charger has a regulator and fit one if needed. Just to provide another view; with low current you can ignore it to some extent, but you'd likely need to buy batteries more often.

• A LiFePO4 battery would tend to have greater overall longevity and endurance in terms of rated discharge against a SLA as you show here. They're more expensive, but maybe a good option in the long run. As with SLA you should have a regulator on the charger, and given they're initially more expensive I'd suggest it's more important. Also while you can use a SLA charger with this chemistry it'd probably be better to tweak it to suit.

I wouldn't recommend LiPo, although you could use such if you were really keen. In this instance definitely get your charging sorted!

Per what Luke said above, IF you go Lithium, you want Lithium IRON phosphate...a.k.a. LifePo4, not lithium ION. They're better, last longer, and SAFER. However, I don't know if they can be charged from a magneto charger or not. I would think so but I'd check with the battery manufacturer first. Also, from my experience with the mag charger on my 11 Torpedo, it just "keeps up" with the coil draw, nothing more. I doubt any will "bring up" a battery that's low on voltage. But, I'm no expert.

I think you'd get better results at a lower overall cost to buy a larger, deep cycle battery than the one shown above, maybe something the size of those used in Volkswagen Beetles years ago. A larger battery is able to carry much more energy, and they are generally much more durable than the very small ones, and more forgiving of the rigors of use. Running a tire pump to inflate high pressure tires requires a significant amount of energy. Running lights, etc. will consume considerable energy over a fairly short time, and may leave you without enough power to pump up a tire or start the car easily. A larger battery can provide more power on demand for such things as running a tire pump or some other accessory, and a larger battery can accept a charge at a higher rate than a small one. The more expensive deep cycle lead acid battery will tolerate extensive depletion between charges without ill effects, allowing you to have a substantial and dependable supply of current available without very frequent charging. I believe the larger battery will give a lot more service and better, more reliable service at a lower cost for the service delivered. I'd also make sure that all wiring is of adequate size, or a size or two larger than the minimum required for the maximum load expected. I'd want a regulated, on-board charging system to assure long battery life, unless you're willing to monitor and regulate the charging system yourself. Even lacking a regulated on board charging system, or any charging system at all, a larger battery would allow longer trips without the need of charging the battery, much like a larger gas tank will allow a longer trip without stopping to gas up.

Steve Jelf wrote: ↑

Wed Aug 17, 2022 1:13 pm

1915 non-starter runabout. 12 volts for LED tail/brake/signals, and coils only when starting. Phone/hot spot charging. 12v tire pump if needed. Magneto battery charger.

What do you electrical/battery experts think of this?

https://www.walmart.com/ip/ML18-12-12V- ... hbdg=L1700

Yes its a battery you want & I want. It is "recharable" meaning deep-cycle, sealed and has 18 ampere hours (Ah) of power!
Its perfect since you have no starter. The load on your system with LED lights & coils is likely only <6amps so you could run 2 hours before thinking about recharging. Likely 6 weeks for just the coils to start it an no lights

Since the Magneto puts out voltages above the desired charging rate I would not use it unless you have a way to regulate that voltage. I used a solar charger/tender. I'm looking for one now...

It's been many years since in school but I would think it would not take much to build a regulator to control over charging, I believe a zener diod maybe? Should be people on this form that are familiar with electronics that could help.

The very small deep cycle battery might do well for a car driven locally or trailered to more distant events. A regulated, on-board charging system would extend its usefullness considerabley. My choice for a non-starter car driven on the road for extended trips would be a larger, deep cycle battery. Charging on the road could often be avoided entirely, and if necessary, the larger battery could accept a charge at a higher rate. A larger battery, even if not fully charged, would provide substantial reserve for accessories and emergencies, such as pumping up flats, while retaining enough power to assure trouble free starts. A small battery would require frequent charging at a low rate, and even if fully charged, it would offer little in the way of reserve capacity. Any on- board charging device would need to be well-regulated in order to prevent early failure of the small battery, and an on-board, engine driven charging device would depend on the engine starting and running for extended periods to be of any use. You could drive a T coast to coast with a one gallon fuel tank and no reserve. Much better to have reserve power on hand in the form of a larger tank.

OK, so now the electronic dummy has a question for all who are recommending a regulator. What do I need to add to this charger to regulate it?

that is essentially what the bulb is doing...it is a current limiter/regulator

which bulb you chose will determine the rate of charge

Here’s another question. What value or type of diode is used. Answers?

that is essentially what the bulb is doing...it is a current limiter/regulator

A current limiter is just that, it limits the current flow to a specific value. A current regulator maintains a specific level of current flow so does limit the current flow from going higher BUT also prevents the current from going lower. The bulb is a crude current limiter But definitely not a current regulator.

I've been using a small 12 volt battery, about the size of a Model T coil for years in both of my 1913's. In my touring, it is under the back seat with my extra coils, and in my runabout it is in the tool compartment in back of the gas tank with my spare coils. They are rechargable, and last for years. They are only used for starting.

OK, that leads to another question. John's mag charger diagram specifies the 1156 bulb for a 6 volt battery. What bulb would be the right limiter for charging 12 volts?

What value or type of diode is used. Answers?

https://dauntlessgeezer.com/DG102.html

If you have limited room and limited height space, and your concerned about battery longevity and power, you can always put TWO or more of those batteries, side by side, and tie both + posts and - posts together. I used 4 of these 12 volt Yuasa sealed lead acid motorcycle batteries, under the rear seat of my 1915 touring car, because I had the room, and they are relatively short in height. I do not have a generator, or a starter, so the system is constant loss. I have LED brake and directional lights on the car and LED driving lights (just in case I get caught out at night) also. While the magneto headlights work well, for what they are, they do not reach far and do not illuminate much at low RPMs. I use a 12 v Battery tender Jr charger, and have permanently installed a quick disconnect harness with a plug and keep the car on the charger when not in use at home. It is simple and quick to unplug it before starting the car.
Because we run a GPS constantly, on T tours, and I start the car on battery, (immediately switching to magneto) is why I used 4 batteries. Might be overkill, but I have attended the Mississippi Cruisin the Coast event which is 11 days long, (nothing like having the oldest car on the street out of 30,000 attendees ) and never have even come close to draining all 4 down. I have had them in the car 4 years now. Everything works great still. This is the battery that I am using:

Steve Jelf wrote: ↑

Thu Aug 18, 2022 10:43 am

OK, that leads to another question. John's mag charger diagram specifies the 1156 bulb for a 6 volt battery. What bulb would be the right limiter for charging 12 volts?
Its my understanding that the bulb was intended to act as a resistor.

What value or type of diode is used. Answers?

https://dauntlessgeezer.com/DG102.html

The above battery has less Ah (12.5) than the one your looking at (18). YTX14-BS is the battery size like Group 1 for a Model T box
But it may be a better battery than the deep-cycle since you will be continually charging it. To prevent over charging you could put a Voltmeter gauge connected in parallel to the load (bulb) to monitor the voltage - then to drain some off turn your lights on now and then

Looks like you have hit upon a solution, searching http://www.mtfca.com/discus/messages/29/23876.html
By John F. Regan on Sunday, January 21, 2007 - 11:32 am:
You can use the same bulb but you will get less charging using a 12V battery because there is less potential difference between the nominal 28VAC of the magneto and the 12V battery versus 28VAC and a 6V battery. If the battery is used only for hot shot starting and possibly powering a brake light then the bulb we supply in the kit probably will work fine. If you need MORE charge then you can use an 1129 bulb (which is a 6V bulb actually) in the circuit with your 12V battery. You cannot use an 1129 bulb to get more charging with 6V battery since it will burn out rather quickly. The bulb we supply in the kit is an industrial bulb that is about the lowest resistance bulb we could find that was 12V. Everage charge rate will also be reduced if you are running a 3:1 rear end due to lower average RPM of engine.
Its been many years since I had to think these things, so fwiw
I believe the bulb is to act like a variable resistor as the magneto spins faster and more voltage the bulb gets brighter = more resistance and then less voltage out V = IR

The bulb does act as a variable resistor. When the bulb filament is cold, it has a fairly low resistance. As the filament gets hotter, its resistance increases dramatically. A partially discharged battery has a low resistance. As the battery is charged, its resistance increases, assuming the voltage applied to charge it is constant. Trouble is, the voltage from a Ford magneto is not constant, and it is often well above the nominmal voltage of a 6 or 12 volt battery. When the voltage applied is higher than the nominal voltage of the battery, it will force current into the battery even if it is fully charged. This causes problems. The bulb as a regulator is far better than nothing, but it cannot match the magneto voltage to the fully-charged battery's float voltage, so overcharging can still occur, especially with a very small battery. As the battery comes up to full charge, its resistance becomes high and the bulb will get dim. This lowers the bulb's resistance and allows the voltage applied to the battery to rise, which can result in overcharging. A larger battery is much less susceptible to this, but it can occur, since the magneto voltage is often well above the battery voltage, and the dim-lit bulb and high resistance of the charged battery do little to reduce it. Current is limited, but voltage is not, so charging will continue even if the battery is fully charged. Using a lower wattage bulb will further limit current, but average charge rate will be reduced, and the system will still not be able to respond to a fully-charged battery. How bright the bulb is glowing can give some indication of the rate of charge, assuming the observation is made at a specific magneto output voltage. Assuming the magneto is delivering, say, 20 volts, a brightly lit bulb would indicate a high charge rate, which would indicate a low state of battery charge. A dimly lit bulb at the same magneto output voltage would indicate the battery was at or near full charge.

...magneto headlights... do not reach far and do not illuminate much at low RPMs.

And if you drive fast enough to see by them, you will outrun them.
I will not drive by mag lights on an unfamiliar dark road since that almost wrecked me.

A variable magneto charger could be put together using a couple of double contact tail light type sockets and bulbs and several switches. A twelve volt bulb and a six volt bulb and switches to select either the high wattage or low wattge filament in each bulb and to switch them into various series or parallel circuits could yield a variety of charging rates.

John Regan-Sorry to clutter up this thread of Steve Jelf's, but I'm sure that Steve would not consider what I have to say to be "OFF TOPIC. We miss you John, and not just because we miss Fun Projects, INC. but we very much miss you too! (...seldom see you comment on the forum) Don't know how to contact you any other way but this note, but I just wanted to mention two things:

Your very considerate note above really might better have said something like,....THE BULB WE USED TO SUPPLY IN THE KIT".... The reason I mention this is because I believe there are still many Model T folks that are not aware that you have retired and that FUN PROJECTS, INC. is no longer.

My second comment is that it's not JUST Fun Projects, Inc. that we miss, but we miss you on the forum as well John,....and in the Chapter News section of the magazine, I never seem to see your name mentioned in the Rockford club activity news,.....hope you and your wife are happy, healthy and still enjoying "the hobby" as always,.....harold

Steve Jelf wrote: ↑

Thu Aug 18, 2022 3:05 pm

Thanks, Frank. I will put the 1129 bulb on my shopping list.
(And thanks to John Regan.)

Another idea is to incorporate a voltmeter and switch into the existing magneto charger. That way you can manually observe what's going on and manually regulate it. Once the car is started there is no need for the battery to be charged. The buzz coils on starting don't take much of battery power. When you turn on the lights, flip the switch to on. I don't think the battery type matters starter or deep-cycle with this other than a starter battery would get more frequent charging of shorter duration to top it off, while the deep-cycle may like less frequent but longer charging time since it is designed for that.






Rule of thumb for estimating charging time is based on the charger rating and battery capacity. For a 10Ah battery and 1 amp charger 10 hrs, same battery and 2amp charger 5 hours