Another Battery Thread

[Lizard King]

Getting my Mk3 out after ten years...looking at batteries...the last battery I ran was a sealed HD Sporster battery. It seemed to work well. The air box is gone so I have room.

I looked at the Odessy 545. It seems expensive and I'd need a new charger to boot. I already have a battery tender.
Looked at the Li-ion batteries....pretty expensive.
Any experience with Battery Mart "Big Crank" Ext-16? Reasonable price (<$100). Claims 19 Ah & 325 CCA...seems like big numbers but anyone can write up a web page that looks good.

I have Dyno Dave's 6 gage cables & am ordering one of his starters...tired of fussing around with my own 4 brush "conversions"....

Thanks.

 

[batrider]

I've been using the Big Crank ETX-15L? for some time. I replaced the 1st one after 6 yrs and it didn't really need it. So now almost 2 years on #2 and 8 yrs. on #1 which is now doing nothing - just gets charged every few months. This is in a '72 with RM24 3 phase Lucas alternator.

 

[rick in seattle]

Hi Lizard,

Try this link:

battery-upgrade-t10295.html?hilit

It's a year old, but little has changed in battery technology. I strongly recommend a new sprag, carefully inspected (and replaced if needed) mating pieces, a 3-phase charging system, Dave's starter, big cables, and a big-ass battery like the Yuasa in the link above. My upgraded Mk3 has been humming along now for 3 years on nothing more than an occasional charge. Starting is instantaneous. By comparison, the OEM battery on my 2010 Harley Dyna gave up after 20 months. I'm impressed with the ruggedness of the Yuasa.

 

[lbridges]

I also bought Dave's starter and am using home made 6-gauge cables. Can't say enough good things about Dave's starter compared to the 4-brush Harley/Norton mismash I used to have in place.

I bought the equivalent to the Big Crank (same OEM I think) down at my local Advance Auto Parts. Cost me 3 bucks more than the online price, but I have a local stocking dealer I can take it to for an exchange if it becomes necessary.

Can't speak to longevity as starter and battery have only been in place for only a very short time, but I'm very happy with performance.

I will add it that I also picked up a box/tri-color LED setup from signaldynamics for a bit less than $30. Three colors with two blinking states indicates a range of 5 different charging conditions instead of two - light ON or light OFF. Admittedly I did this since I also went to negative ground and the ignition warning light module (assimilator for earlier models) doesn't work with negative ground.

 

[Lizard King]

Thanks for the info....I already have Dave's cables & a 3 phase charging system.

Question - why would someone want to change from pos ground to neg ground?

 

[rick in seattle]

To use useful modern stuff like LED lights, battery tenders, power take-off points, GPS devices, and voltage meters without having to worry about popping fuses by grounding the -12v hot side of a positive-ground system. It's an easy conversion, but does require an after-market assimillator (or no assimillator, if you add a voltage meter) and a rectifier/regulator module. There are many posts in the archives on this topic, including from your's truely.

 

[pete.v]

I feel that the electrical need should be a less than what the stator will produce (duh). With a 3 phase unit, you should have little to no worries.

The battery acts as the middle man between the charging system (stator and reg/rec) and the demand (lights, starter, EI unit and so on). To minimize an under and over charging situation, to prolong the battery life and to ease the duties of the reg/rec unit, a battery should come close to and slightly lower in capacity (AH) in relation to the stator output.

An example would be, a 180 watt stator divided by 12v = 15amps. A 14ah battery would be perfect.
Running a 16ah to 18ah or higher may cause the stator to run efficiently (get hot) where as a 12ah will cause the reg/rec unit to over work (get hot). In either case there is an imbalance within the system.

Whether 3 or single phase, the battery should match the stator and with the proper sized reg/rec unit (given) the charging system will harmonize nicely to feed the electrical need of the bike.
This is not to say that there isn't some give and take here, there is. It is to say that bigger or smaller is not necessarily better.
The End:

 

[montelatici]

I bought an 8 cell Li-ion made by Ballistic for a little over 100 bucks. It discharges less than 10% in a year and since its under load performance when starting is 3-4 volts higher than conventional batteries, it has solved my electric start problem. Also, the blinkers now work and blink almost normally.

 

[Lizard King]

Li ion seems to be arond $140 now....do they need special charger to double the price???

 

[tylerdntexas]

I bought the Odyssey PC545 in August 2011 for $125 shipped from Battery Mart. My Mk3 starts almost instantly ever since. Running 2 brush Prestolite starter with new sprag clutch/engine sprocket. My battery tender works fine on the PC545. I have looked at Dyno Daves starter but can't see buying one when mine starts in 1-2 seconds anytime. The sprag design requires a powerful battery to start the bike up and not let it kick back, which a lesser battery will do, which is how you ruin sprag clutches/engine sprockets. When you replace your sprag have a look at the engine sprocket inner race and also the starter drive gear(that runs on the sprag) outer surface. These surfaces must be unworn or else you're wasting your money with that new sprag.

 

[Lizard King]

Interesting....I shied away from the Odyssey because I didn't want to buy another charger - BatteryMart makes a pretty hard sale on the necessity for a high dollar charger for the Odyssey.

 

[Lizard King]

It looks like it comes down to the Odyssey at around $100, a Li Ion at around $120 - $150 (8 cell or 12 cell), and a Big Crank at around $100. I replaced my air box years ago when I convereted to a single Mikunni so I'd have the room for the Big Crank 30L.
Maybe the proponets of each should arm rassel to see which battery is better.

Seriously. I'd probably go with the Odyssey except they want me to buy a $70 charger, claiming my battery tender won't do the job. Now it's $170 and the Li Ion looks like a more viable option - except it may be unproven technology. I thought I read I could use my tender on it - thought it probably wouldn't need much tending. Also, at a $50 savings, the Big Crank comes back into play.

I'M SO CONFUSED.

I have other mods to buy and hate to blow my budget of a freaking battery. I just got one of Dave's starters and his heavy gage wires. I replaced my zeener & rectifier with a Tympanium but still running single phase. Any last thoughts? Otherwise I'll play rock, paper, scissors against myself...

Thanks again for your suggestions.....

 

[Saber13]

Lizard,
I"ve been running a Shorai Lithium Iron battery for almost a year on my 75 MKIII. Due to recovery time from a spinal injury, most of that time the bike ahs set in the garage except for a few trips around the block when my wifw wasn't looking. Bottom line, battery has been hooked up to a Battery tender Jr for as much as a week at a time with no ill effects. Runnig factory stater and Enki starts every time.

 

[Lizard King]

Chuck,
Are you running the 8 cell or 12 cell battery?
I'm somewhat partial to Li Ion as many of my hand power tools use them and they're pretty sweet for that application.