Batteries Dying???
Seasoned HDF Member
Joined: Mar 2010
Posts: 21,003
Likes: 7,534
From: Poolville
Hello sorry if I sound ignorant but I am when it comes to electronics I have a 1984 FLTC 1340 EVO that I restored and rebuilt had it for the last eight years now and in the past 3 years I have been through like 3 4 batteries I have replaced the stator/rotor as well as the regulator last year was 22amp bumped it to a 32amp now if I ride the bike just normally 65-75ish she seems fine but some days I tend to push her over a bit 85-100 if I do this to many times the damn battery just dies??? I have did all the checks per manual ground test the entire bike is well grounded with ground strap going from frame to inner primary cleaned paint off ect If I hook a test light on the POS term and run it pretty much all over the bike I get a bright light using volt meter I have the same volts around 12.70-75 pretty much everywhere even at the regulator it also is well grounded with the extra wire to frame. new battery charged I always keep it on a tender even previous ones I ride every weekend my bike does not have the draws like these new bikes when shes off shes off do I really need a tender? no draws I tested that to so here's my question with the new battery its a DEKA at rest it is at 12.75 now for the charging part at idle she is at 12.30ish at 1500 RPM it is at 13.50v 13.60 at 3000RMP it is at 14.09v at 4000 14.13v does not go past so I dont see overcharging? am I golden here? or do I need to see 14.30-14.50? I hear this or that some say 14 is good others say low? a buddy of mine is a certified mechanic he also is STUMPED WTH? cant keep going through batteries tows ect costing me not so much the money its the wife LOL afraid she may burn the thing to the ground any help here would be really appreciated I even purchased a battery tester for batt test,crank,and charging they all PASSED if any of you guys my know maybe I'm not checking something here? how bout the breakers? there are no draws no extra goodies on the bike maybe hooking up an extra ground from fame to engine? not sure that would do any good if any of you have some advice please let me know and yes I even have checked the connection from reg to stator and have the metal bracket that attaches from case to the outside plug that keeps it from vibrating out learned that lesson the hard way 
Thanks
Thanks
12.75 Volts is a perfectly healthy battery. I don't believe you have battery issues.
You said,
"with the new battery its a DEKA at rest it is at 12.75 now for the charging part at idle she is at 12.30ish"
12.30 ish at idle is not good and by 2000 rpm it should be in the 14.1-14.3 volts area.
You never stated an AC test on the alternator (stator). @ idle you should see in the vicinity of 16 vac and by 2000 rpm you should see 33 vac. If not your alternator is "NOT" putting out enough alternating current till higher rpm's.. A week magnet on the rotor can cause this..
If my charging system is not putting out the required vac at 2000 rpm, I'm replacing it with either a Compu-Fire or most definitely a Cycle Electric.. Yeah they're pretty pricy but well worth the investment.. Hell at idle my Cycle Electric is putting out 13.8 volts..
Last edited by 98hotrodfatboy; Nov 6, 2023 at 11:56 PM.
Road Captain
Joined: Jul 2023
Posts: 509
Likes: 390
From: So Western Ohio
I bought my '14 XL1200 back in April. The P.O. had just put a new battery in the previous fall and never rode it. He kept it on a tender all winter. When I got it, 1 start out of 5 the starter would bog, kill all the lights, then crank it over and start. After about a thousand miles this summer, with much of the down time on a tender, it still bogs then starts 2 out of 3 times. Now I'll get to the point.
This Sportster has a 10 to 1 compression ratio (some specs claim 10.5 to 1) and the starter is barely adequate to turn it over. HD fit a battery of 240 CCA to these bikes. My personal theory is that the batteries just can't take the abuse of total current draw almost every start. My 1999 Yamaha Road Star (1600 cc, 8.5 to 1 CR) had a small geared starter but a solenoid operated compression release that allowed it to start smoothly and easily. Over 14 years it had its (cheap) battery replaced (lead acid with water) 3 times. It was left on a tender during winter storage.
The Sportster needs a compression release, a lower compression ratio, or a larger battery. By next spring I'm going to put a 315 CCA battery in it and keep an eye on the battery voltage to see what's going on with it.
This Sportster has a 10 to 1 compression ratio (some specs claim 10.5 to 1) and the starter is barely adequate to turn it over. HD fit a battery of 240 CCA to these bikes. My personal theory is that the batteries just can't take the abuse of total current draw almost every start. My 1999 Yamaha Road Star (1600 cc, 8.5 to 1 CR) had a small geared starter but a solenoid operated compression release that allowed it to start smoothly and easily. Over 14 years it had its (cheap) battery replaced (lead acid with water) 3 times. It was left on a tender during winter storage.
The Sportster needs a compression release, a lower compression ratio, or a larger battery. By next spring I'm going to put a 315 CCA battery in it and keep an eye on the battery voltage to see what's going on with it.
Last edited by Rufus13; Nov 7, 2023 at 01:53 AM.
Road Captain
Joined: Jul 2023
Posts: 509
Likes: 390
From: So Western Ohio
Today I put the bike in 2nd gear and rolled it back against compression before starting. There was only a very short hesitation (maybe 1/20th a second) and it started. After a short ride I started it without rolling it back and it bogged down bad so I let go of the button. Now the check engine light was on. Switch off, back on, hit the button and it started but raced up to about 2500 and held there for a couple seconds.
This engine has some serious compression. I think that's what is gradually killing the battery. It runs like a striped azz ape.. from 20 to 90 mph it will pull hard on your shoulders. It needs a dyno run to find out some things.
This engine has some serious compression. I think that's what is gradually killing the battery. It runs like a striped azz ape.. from 20 to 90 mph it will pull hard on your shoulders. It needs a dyno run to find out some things.
Road Captain
Joined: Jul 2023
Posts: 509
Likes: 390
From: So Western Ohio
Thanks, man. I don't have one but I'll check around. It couldn't be too high, the bike was apparently stock other than some super loud straight thru mufflers. Stock airbox, etc. I got a big air cleaner, changed the mufflers, got an external breather and cleaned the injectors.. nothing really.
The PO mentioned how it needed a battery when his wife bought it, she hardly rode it at all, then put a new one in before running the ad to sell it. Now here it is again, struggling to start sometimes. Today I rolled it backwards in gear til it stopped, put it in neutral and it started up normally. This gives the starter a chance to build some momentum from the flywheels and basket before the big load hits.
I searched through the XL forum and the problem has haunted Sportsters for years. They mentioned loose or corroded leads from the battery, lifters leaking off over a few days of sitting (letting the intake valve close too early) and other voodoo.
These bikes are designed for trim looks. Compact. A big battery would present a problem to hide.
Dano has an interesting angle up above, too. My bike has always been kept on tenders. PO did it, I've been doing it.. It always worked fine on my other bikes. They had lead/acid batteries, though. My new battery will get charged as needed, not as a routine. I might even try to get those caps off of there.
So, thanks to Dano, too! I like to learn one new thing every day.
The PO mentioned how it needed a battery when his wife bought it, she hardly rode it at all, then put a new one in before running the ad to sell it. Now here it is again, struggling to start sometimes. Today I rolled it backwards in gear til it stopped, put it in neutral and it started up normally. This gives the starter a chance to build some momentum from the flywheels and basket before the big load hits.
I searched through the XL forum and the problem has haunted Sportsters for years. They mentioned loose or corroded leads from the battery, lifters leaking off over a few days of sitting (letting the intake valve close too early) and other voodoo.
These bikes are designed for trim looks. Compact. A big battery would present a problem to hide.
Dano has an interesting angle up above, too. My bike has always been kept on tenders. PO did it, I've been doing it.. It always worked fine on my other bikes. They had lead/acid batteries, though. My new battery will get charged as needed, not as a routine. I might even try to get those caps off of there.
So, thanks to Dano, too! I like to learn one new thing every day.
Road Captain
Joined: Jul 2023
Posts: 509
Likes: 390
From: So Western Ohio
One thing I just learned today about the starter stalling out- bump the starter button, release it/ then hit it. This works the same as pushing it back in gear. I'll still put a stronger battery in by spring.
Cruiser
Joined: Aug 2015
Posts: 108
Likes: 18
From: BC, Canada
Seasoned HDF Member
Joined: Jul 2014
Posts: 8,563
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From: Cental, MI
See Post #20
Seasoned HDF Member
Joined: Jun 2015
Posts: 10,276
Likes: 7,756
From: West Central FL
I've been having a similar problem with wit my '93 FLSTC. I've gone through three batteries in the last two years most recent one about eight weeks ago. Have replaced every single componant in the ignition/starter circuit and still have the same problem. Now I put it on a tender an hour before I go out. I'm begining to think these DEKA batteries are boxes of shizz!