Author Topic: Total-Loss Ignition Battery Voltage (Read 2785 times)

Old Scrambler · « **on:** February 25, 2021, 11:29:27 AM »

I am attempting to maintain full voltage from the battery to the coils throughout the time and rpm-range of my C.B.R. An old trick used by the Menard's NASCAR team was to run an additional 6v battery in parallel (18v) to supply enough juice to their Buick V-6. I know of a person from that pit-crew who also used this method on an LSR bike. The higher voltage is only felt by the coils and is supposedly a non-issue at high rpms. I was thinking of being able to switch the 6v battery on and off to protect the coils.........otherwise use the strongest conventional coils known from a 90's-era Ford Ranger.

My battery is a 12v Lithium.....will be new so recommendations are welcome. Coils are Dyna 5-Ohm.........No other draw to the battery other than a wire going to the kill-switch which acts as the on-off ignition.

Any help from the tech-gurus on this board would be appreciated.

slikwilli420 · « **Reply #1 on:** February 25, 2021, 11:44:36 AM »

Hey OS, its all about how much draw your system uses when running. Understanding you are running at higher RPM for longer than a road race bike, but still very relevant. I charge my 12 cell antigravity between sessions just because, but plenty of guys go all day on one battery charge. My battery is rated at 8 amp hours, meaning it can draw 8 amps for 1 hour before it needs some charging. My system, a Dyna S and 3 ohm coils, rev limiter box from Dyna, an oil pressure guage and a Scitsu tach draw just over half that much, so I should be able to run for nearly 2 hours before needing to charge. That would get me 4 practice sessions and a race before I needed charging. My 2 cents on the matter.

Old Scrambler · « **Reply #2 on:** February 25, 2021, 12:15:51 PM »

Thanks for the 2-cents..........its good basic info...........BUT......Do you know when your battery is no longer supplying 12.6v to the coils? I'm told that at high rpms the coils need to draw at least 12.6v to maintain full spark due to the reduced length of dwell-time. My third, fourth, and fifth-gear high rpm run time is approximately 55-seconds over about 2-miles.

dragracer · « **Reply #3 on:** February 25, 2021, 01:06:57 PM »

If I recall, the Anti Gravity battery I use in my no bar KZ dragbike is 13.4volts, not 12 volts. Its a 16 cell battery and runs the fuel pump for my nitrous system as well as the nitrous solenoids. It provides power to my Schnitz ignition controller and 7ohm coils. Would using one of those batteries help to stay about your threshold?? I know my run times are short compared to yours.

slikwilli420 · « **Reply #4 on:** February 25, 2021, 01:20:25 PM »

Quote from: Old Scrambler on February 25, 2021, 12:15:51 PM

Thanks for the 2-cents..........its good basic info...........BUT......Do you know when your battery is no longer supplying 12.6v to the coils? I'm told that at high rpms the coils need to draw at least 12.6v to maintain full spark due to the reduced length of dwell-time. My third, fourth, and fifth-gear high rpm run time is approximately 55-seconds over about 2-miles.

My understanding is they maintain voltage (mine runs about 13.3v) until the draw of components uses up the amp hours then voltage does like a rock. Mine never comes off the track under about 13.1v.

bwaller · « **Reply #5 on:** February 25, 2021, 04:09:50 PM »

I can't comment on your question OS, but I run an 8 cell, 13.3 fully juiced. Fine for what we need, but have a spare. I do run a heavier wire from the battery to a relay and coils. The kill switch simply triggers the relay so coils always receive full power.

Old Scrambler · « **Reply #6 on:** February 25, 2021, 05:01:38 PM »

Thanks Guys.............I think I have it. 12v as usual with a toggle on positive wire........plus 6v wired in series with positive to toggle and for 18v when needed

I am wondering if the real issue is my battery charger. I may not be getting a FULL charge after 2 or 3 cycles.

johno · « **Reply #7 on:** February 27, 2021, 05:11:37 PM »

Dont stress about it Den, charge battery up every night ( and spare) if the voltage is too low it will miss, then you'll know, likely that will never happen if you charge daily, so relax mate, spend the time working on the gearing or a big flow head, I reckon that will net you better value

cheers johno

turboguzzi · « **Reply #8 on:** February 28, 2021, 03:20:31 AM »

i think brent went through this also... all Dyna system are very current hungry for now apparent reason. brent and i run OEM suzuki sytems, box and coils and these consume like a fraction of a dyna.... my 3.2 a/H last me quite a few 20 minutes sessions without much drop. food for thought.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #9 on:** February 28, 2021, 07:37:28 AM »

Quote from: johno on February 27, 2021, 05:11:37 PM

Dont stress about it Den, charge battery up every night ( and spare) if the voltage is too low it will miss, then you'll know, likely that will never happen if you charge daily, so relax mate, spend the time working on the gearing or a big flow head, I reckon that will net you better value
cheers johno

If memory serves me I believe Dennis missed a nice record when the battery died on the return run of his 149+mph pass.

If you hit the ignition with 18V will it withstand that much voltage?

Maybe just swap batteries after each set of passes

Old Scrambler · « **Reply #10 on:** February 28, 2021, 10:44:06 AM »

I'm Listening...........good food for thought......bike already has more than one Yamaha and Kawasaki part........maybe add Suzuki?

Jerry has a good memory except it was 147.9 mph...........150+ is still the goal

bwaller · « **Reply #11 on:** February 28, 2021, 01:52:03 PM »

TG is correct, the Dyno2000 I used was hungry for power, I'm not sure if this is commonplace. Mine kept giving me other problems that required replacement.

I have read these Lithium batteries are good for 1000 charges. I keep at least two and always have one charged, any question....change batteries. Even so, things happen. The race gets red flagged and bikes aren't allowed to pit, two more sighting laps, etc, etc. We've seen forty plus minutes run time on an 8 cell with this ignition and well over 12V remaining.

For sure let a battery rest a while before charging. I know, this is no damned help!

Old Scrambler · « **Reply #12 on:** February 28, 2021, 04:04:55 PM »

Let it Rest Awhile................That's helpful...........I was using 1st generation Deltran 8-cell units. The added 6-volt unit is more of safety-stop. On a good day on the salt, I have had 5 runs......so even having two 12v batteries may not be enough.

scottly · « **Reply #13 on:** February 28, 2021, 07:12:51 PM »

First, what ignition system are you using, Dennis? The stock points and coils draw about 2.5 amps at low RPMs and decrease to about 1.5 amps at high RPMs, due to the inductance of the coils.
In normal conditions with a charging system, the running voltage is more like 14.5V.
A lithium battery has a higher initial voltage than a lead acid, but under load it will still be less than 14.5, and, as Matt stated, when they go dead it's all at once, like dropping from 12V to 8V within seconds.
Beware of "amp hour equivalent" ratings given to lithium batteries, as it refers more to starting power than steady drain. Even with lead acid, amp/hr ratings have a time associated, as in 10 amp hrs at a 10 hour rate. This means you can draw 1 amp for 10 hours, but it doesn't mean you can draw 10 amps for 1 hour; it will be less than 1 hour due to the Peukurt (sp?) effect of the battery in question.
I would look for a battery with a nominal voltage of 14V. My first LiFe battery came from member Kayaker, and was 4 A123 cells in series that he assembled: 5 cells in series would be a nominal 14V.

Old Scrambler · « **Reply #14 on:** March 01, 2021, 09:56:29 AM »

Scottly.....I use a Dyna S with 5-Ohm green coils and Dyna wires. I will contact Kayaker for advice............and I hope your personal health is improving

Jerry Rxman Griffin aka MuthaF'er · « **Reply #15 on:** March 01, 2021, 10:37:26 AM »

Green are 3ohm

Old Scrambler · « **Reply #16 on:** March 01, 2021, 12:56:31 PM »

Thanks, Jerry................I get confused since I change things up over the years

scottly · « **Reply #17 on:** March 01, 2021, 06:34:05 PM »

The batteries from Kayaker were a one time thing; I got one of the last ones. It would be possible to assemble a 15V (I misspoke when I said 5 lithium cells in series would be 14V) from individual cells, but I'm not sure it's necessary.
How old is the Dyna? Are you sure it was a dead battery on the return run that Jerry mentioned?

Old Scrambler · « **Reply #18 on:** March 02, 2021, 08:38:45 AM »

Yep..............changed the battery and got in line to run again.........weather changed so ran about 4-mph slower

scottly · « **Reply #19 on:** March 05, 2021, 08:14:39 PM »

Dennis, you might want to run one of those small onboard voltmeters, so you have an idea of your actual battery voltage? The Deltran/ Battery Tender batteries claim to have a low voltage cut-off circuit which shuts off the battery output when the voltage drops to a certain level, to protect the battery?

I can't see this as being desirable in any condition: imagine tooling down the interstate in the left lane and the battery decides to turn itself off with no warning.

You mentioned your charger may have been suspect? You need to do some testing of both the charger and the battery. For starters, monitor the battery voltage while charging and see if it gets up to 14.4V. Next, with a fully charged battery, connect a load, such as a 60W headlight bulb, which will draw about 4.5 amps, and monitor the battery voltage over time. The 4 cell battery I mentioned would take about 20 minutes to drop to 12V. As soon as it drops to 12V, remove the load and recharge the battery.

Old Scrambler · « **Reply #20 on:** March 06, 2021, 09:43:32 AM »

Thanks Scottly........Will take under advisement when I purchase new batteries...........

dragracer · « **Reply #21 on:** March 07, 2021, 01:15:30 PM »

Look into the Scorpion lithium batteries also. That's what I use as my primary battery in the mono shock bike.

Old Scrambler · « **Reply #22 on:** March 07, 2021, 03:50:13 PM »

Noted........

Don R · « **Reply #23 on:** April 03, 2021, 09:26:30 PM »

Drag racers routinely use 16V batteries.
https://www.speedaddicts.com/motorcycle/antigravity-16-volt-lithium-battery-vtx-20r-500ca-right-neg?CATARGETID=120220100000125527&CADevice=c&gclid=CjwKCAjwpKCDBhBPEiwAFgBzj4UgfAzykYpmNx48gvPV7j6NTfniEhzDMOw92gyXjOgLfSu62V-ajBoC8dcQAvD_BwE

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Author Topic: Total-Loss Ignition Battery Voltage (Read 2785 times)