Britbike forum

Classic British SparesKlempf British PartsBaxter CycleBritBike Sponsor SteadfastCyclesThe Bonneville ShopLowbrow CustomsSRM EngineeringGirling Classic MotorcycleLucas Classic MotorcycleHepolite PistonsIndustrial tec supply

Upgrade your membership: Premium Membership Gold Membership

New Sponsor post
Cyber Monday Sale - 10% off at The Bonneville Shop
by The Bonneville Shop - 11/29/21 5:34 pm
New FAQ post
How to find my own threads?
by reverb - 11/20/21 3:55 pm
Manuals on DVD - Buy 4 for 3
All 4 DVD Manual
Member Spotlight
Posts: 3,637
Joined: February 2011
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Top Posters(30 Days)
Rohan 84
NickL 69
Top Likes Received (30 Days)
kevin 23
Newest Members
bradders, tizianouk, Breeze, FORTYTWO, TomV
11,929 Registered Users
Who's Online Now
4 members (Deadstiffcatt, TomV, Brian Brown, blueboat), 23 guests, and 17 robots.
Key: Admin, Global Mod, Mod
Thread Like Summary
Gary Caines, Gordon Gray, HughdeMann, TinkererToo
Total Likes: 4
Original Post (Thread Starter)
by scott garland
scott garland
I have had to replace my battery a couple of time since I put the bike together (stock basket case) 6 years ago. The other day went for a ride with Antique Motorcycle Club San Diego chapter. I was a short ride 109 miles. We were in a lights on two lane mountain area and my bike kept stalling. Turns out the battery was flat as a hat. Anyway got a toe home to troubleshoot. Ordered a lead acid battery from Low Brow Customs and it is in transit. My question is, is there a gell-cell battery available for the 68 Bonneville and TR6R ? A good portion of the failure is my fault for not checking battery condition before the ride. I checked tire and oil and nuts and bolts. Swing and a miss on the battery.
Liked Replies
by desco
I have this battery in both bikes. Along with two of the Battery Tender Juniors over to right in this ad. Sealed, no hose to leak acid all over and they last for years. Make sure your charging system is up to snuff. I leave the battery tenders on year round. Heat kills batteries too.
Also a little shorter than a stock battery so it lessons the chance of a short to the seat pan.
1 member likes this
by TR7RVMan
Hi Scott, If bike had been working good & had working lights etc on the pre ride visual inspection, you had no reason to test battery. You never know when a failure can happen to diode or zener. Indeed a battery can open circuit internally during a ride. So you may not have been able to prevent a tow. Of course you want to test, verify all is well with charging system after installing new battery. Be sure to charge new battery before installing. Depending on state of charge & your charger, often an hour is enough. Charge until voltage is at least 12.6v with charger removed. This is very important. Let it set overnight & verify voltage is 12.6v or more. Sitting allows the top charge to dissipate which prevents getting false full charge voltage.

I've had very good results with MotoBatt MB9U as well. It is important to know that many sellers are selling basically aged batteries. Counterfeit batteries are always a problem. I only buy from MotoBatt direct mail order. I'm in California USA. Have installed in many bikes. Always to good results. They are specifically designed to resist vibration. However no matter the quality, any battery may be a dud & have some internal failure. Hopefully it's still covered by warranty.

Looks to me like the Scorpion is a quality battery also. Scorpion is 9AH while MotoBatt is11Ah. So MotoBatt will have more in city type riding capacity.

I have not found heat to damage the MotoBatt at all. Most all my riding friends are using MB9U. I ride regularly in 100f+ temps hour after hour all day. 110f is not that uncommon. Hottest has been 117f. I've seen no heat failures. Cold here is only lower 30s. Not a problem, but that's not cold. It's been outside overnight as cold as 23f a few times. No problems. Normal storage is in garage about 45-55f in winter. Not cold at all.

Getting to charging system. Testing output is a must. One failed diode in rectifier will cause that sort of problem when you know it would be fine otherwise on same road test. Of course any poor connections or wiring will give low out put as well.

Test output at 3000, 4000 with headlights on & off. Please report results. You MUST have fully charged known good battery to get accurate output test. Failing or failed battery will suck the current & give false low reading. Again battery MUST be fully charged & good. A defective or not fully charged new battery will give false test voltage. After charging new battery. Let is set at few hours, better overnight. Test voltage of battery. (key off if installed, but best to disconnect one wire). Voltage must be at least 12.6v.

The output of 2 wire stator is very closely matched to factory consumers like bulbs & ignition systems.

Lesser quality voltmeters will read fine motor off. Starting motor if meter reads erratic or crazy it is not compatible with Triumphs. The cheap Harbor Freight volt meter will drive you nuts with motor running. Trust me don't use it!

Diodes in rectifier can be bench tested with ohm meter for rough test. Testing under load with at least 21w test bulb will give accurate test. Volt dropping will give very accurate test of rectifier. The end plates can have poor connection to the bolt head & nut (the nut next to first plate). If loose. Hold all plates with one hand so they can't rotate. counter hold bolt head if vise jaws, tighten nut. The rectifiers are not as fragile as some think. If diode pops out of disc, it was ready to fail or already failed anyway. When removing/installing the rectifier put wrench on bolt head & counter hold the bolt head while removing mounting nut. Of course mounting nut must be tight & rectifier must have good ground.

Since the output of 2 wire alternator is so balanced to consumers any larger loads can soon overpower the output. Big light bulbs or extra lights will cause this. Output is directly related to rpm. If you ride on open roads at 3500 rpm & higher you can get away with some larger consumers. If you do city riding with stop lights almost every block the charging system will struggle. This is where the 11A will show its strength over a 9A battery. I live in city east of San Francisco. City traffic lights & stop/go traffic for miles is a fact of life. Daytime headlight on is the law. Add stop light being on often, plus turn signals if equipped, voltage goes down fairly quickly. LED bulbs can be a real help here. LED bulbs will NOT make up for fault in charging system. Don't fall into that trap. The real cure is high output 3 phase stator, regulator/rectifier system. That's another subject.

Should you feel rotor magnetism, stator is defective, you can purchase 1 ohm, 100w resistor on eBay under $10. Make a simple wire harness & using AC volt meter test the actual stator output. It won't tell which part is bad, but it will tell if bad or good voltage output. If you have known good stator & output is low, the rotor magnets are bad.

The factory test for zener diode requires an amp meter to test by shop manual. However if you headlight off & head light on voltage is good, your good to go. If too high look into zener system. If too low look into charging system side. Again these tests must have fully charged known good battery.
1 member likes this
I've been using something like this in my '65 TR6 for the last few years (not this actual one).
To put it in context I converted to 12v early on in ownership, don't do much of a mileage, and overlook battery maintenance. As a result, I wrecked a new lead acid Varta over two or 3 years. So the idea of a cheap maintenance free battery had appeal. I never remove it from the bike, and in that time have trickle charged it a couple of times. Critics say the cases of these alarm batteries aren't robust enough for a motorcycle, but mine sits on a rubber mat and has been fine so far.
1 member likes this
by Mark Z
Mark Z
Reading this thread gave me a chuckle - I'm currently using a Motobatt AGM (MB9U) in my A65, and I have no side panels. When I first installed the battery, everyone who saw it said "Cover that battery!", so I had a local leather worker make this cover for me:
[Linked Image from]
By the way, my Motobatt is holding up fine so far, and I really do believe the extra capacity (it's 11 amp-hours) helps it hold a charge when idling with the headlamp on, as for traffic lights, etc.
1 member likes this
Job CycleBritish Cycle SupplyMorries PlaceKlempf British PartsPodtronicVintage MagazineBSA Unit SinglesBritBike SponsorBritish Tools & FastenersBritBike SponsorBritBike Sponsor

© 1996-2021
Powered by UBB.threads™ PHP Forum Software 7.7.5