FJRiders.com

Any issues using a regular 2 amp trickle charger on the new FJR batteries?

Is does show 2 a 5~10 hrs on the battery.



Canadian FJR

I can’t help because I don’t trickle charge. I ride the fjr all year. The Harley and the bmw do go dead from time to time. I sock them with the full almighty power of the 1970’s (Sears brand) 6 or 12v charger (always set to 12, 6 never has an effect). This thing is ancient. It’s an heirloom.

Always puts them right, batteries suffer no ill effects. Shockingly....

Canadian FJR wrote: ↑Tue Dec 29, 2020 6:24 pm Any issues using a regular 2 amp trickle charger on the new FJR batteries?

Is does show 2 a 5~10 hrs on the battery.

Canadian FJR

Not sure what your last sentence meant.

Unless you know exactly what you are doing, a trickle charger should not be used. A trickle charger left on after the battery is fully charged will likely overcharge it, reducing its life.

Get an intelligent charger, this will assess the battery's condition and adjust the charge rate appropriately. It can be left connected indefinitely and will top the battery up as and when necessary if charge is lost due to leakage or any residual bike drain.

That is what is stamped on the battery

2 a 5~10 hrs


Canadian FJR

Canadian FJR wrote: ↑Tue Dec 29, 2020 7:05 pm That is what is stamped on the battery

2 a 5~10 hrs


Canadian FJR

I would interpret that as 5-10 hours to fully charge from flat using a (nominal) 2 amp charger. For a 12 ampere hour AGM battery, this would be a suitable charge rate between C/5 and C/10 where C is the ampere hour (capacity) rating of the battery. (Charging process is not 100% efficient.) Charger should be disconnected when charge is complete. A slower charge rate is perfectly acceptable but I would not charge at a higher rate unless I had to. Note: Boosting a dead battery and recharging by going for a ride is very hard on the battery. The charging system charges it at a much higher rate than optimum.

It is important not to overcharge which is what mcatrophy is saying (or charge too quickly). A simple trickle charger just keeps on going, even if the battery is full and will eventually ruin the battery by overcharging. A battery tender or an intelligent charger senses when the battery is full and drops the output voltage to a "float" level that will maintain full charge indefinitely without overcharging or damaging the battery. This is around 13.6 V and will vary as a function of ambient temperature. (The better battery tenders are temperature compensated.)

The Yuasa OEM battery has a very low "self-discharge" rate - less than a couple percent per month for a new battery in good condition. The FJR has a pretty low parasitic draw and shouldn't deplete the battery to a significant extent over a period of months. If you are concerned about drawing the battery down during winter layoff, the battery can be disconnected and all you need to worry about is self-discharge.

It probably isn't strictly necessary to use a tender for a longer layoff but I check voltage and usually top mine off with a slow charge a couple of times over the winter. I managed 10 years and well over 200,000 km on my OEM battery on the '07. Never trickle charged it and only unhooked it some years. My 2011 still has the OEM battery (but with fewer km, so far).

I probably said a lot more than necessary (don't know your technical background wrt batteries) but for a simple answer, a 2 amp trickle charger is OK but take it off once the battery is charged. A simple transformer-type trickle charger, is neither constant voltage nor constant current. Take care and don't assume it is putting out what it says. The AGM battery may be charged up to 2.4V/cell x 6 cells = 14.4 V at which time the voltage should be reduced to the "float" level for maintenance.

Tons of good battery information here:
https://batteryuniversity.com/learn/art ... 3xZRtvolew

Thanks Ross, that’s the info I was looking for.




Canadian FJR

Are you using a battery tender?

It’s a variable charger with 6,4 & 2 amp settings.
Has auto shut off.

My main question was if the new batteries needed a special type of charger.


Canadian FJR

For best battery health, I would not charge a 12 ampere hour AGM battery at a rate in excess of 2 amps.

You can't use the regular battery tender with a lithium battery. They charge a lead acid battery and then shut off. They don't know when to stop charging a lithium battery. Battery tender makes a new version for the lithium battery.

Per Yuasa, if you have a new AGM battery, it needs to be initially charged at no more than 2 amps for 5-10 hours, I usually do overnight. Agree with Ross, I wouldn't just drop a new (previously uncharged) battery into a bike, charge rate is too high for that initial charge.
I have charged a Shorai with nothing but a Battery Tender for several years. They do recommend their own charger and I see why, but a Battery Tender will work if you have nothing else. The Shorai died after about 7 years. As I understand it, a Battery Tender does not really shut off, it maintains the charge at 13.2V, will kick in if it goes below that. The bad part for a regular Battery Tender on a lithium apparently is the desulphation mode, which initially puts the charge voltage at 14V, however, the bike does too constantly.

WRT: Battery Tender

I remove my battery every year for storage inside. I hook it up to the Battery Tender (Not 'trickle charger) and it tops it up then float charges it all winter. It's plugged in right now. This is the 7th winter for that battery. I'm guessing this is perfectly acceptable.

I've got 99 problems, but my bike battery ain't one.

A traditional "trickle charger" is transformer and a diode, nothing more. The current is limited by the size of the transformer. Was found long ago the traditional wet lead-acid car battery could benefit from 0.5A or 1.0A for a month or two. The more we learned about batteries the better we can make a maintainer to do better than a trickle charger.

I don't think it matters much if a modern maintainer is 1A, 2A, or 4A. But there are different algorithms for wet, AGM, and lithium chemistries. The better will have a switch to set modes. Lesser will claim to be good for all.

Is harmful to continually charge a lithium battery. A proper maintainer will charge lithium to a point then stop. If need be it will resume in the future.