CB400F Battery

[MikeSB6]

Hello All and Happy Christmas,

      could someone please tell me if there is a smaller, lighter than standard battery that will fit the CB400F while still allowing use of the electric starter etc?

       Cheers, MikeJ

[ST1100]

Some LiFePO4 types come to mind.
However, upgrade to a modern, solid-state VR/R seems mandatory, running those battery types with the old, mechanical prone to voltage spikes VR bear definite risks...
You'll also need a suitable battery charger/tender for those LiFePO things... both still pricey...

A Skyrich Lithium YB14L-A2, seems to fit, lower height and only 1.2kg makes them popular for café and bobber projects.

Another issue is the internal resistance at lower temps; the battery needs to actually warm up first, means to flick ignition and lights on for like 30+ seconds before hitting the starter button.

[MikeSB6]

Thanks ST,

    it all sounds a bit Hi-tech for me, I'll probably look for a slightly smaller gell battery but thanks for the info,

      Cheers, MikeJ

[Dave_Canada]

The electric starter is not such a killer load that smaller bike batteries won't turn it over. You want at least 75 CCA (actual starting current is 50-75A, I believe) but bike batteries don't always give CCA specs. Any 12V battery allowed for a bike with electric start should be OK for a 400F, this is not a hard engine to turn over. Batteries for bikes with kick only (most dirt bikes) ... probably not.
The battery Amp-Hour rating tells you how long you can crank the engine. If you plan on removing the kickstarter and don't plan to bump start it, then it's going to need to crank a long time for cold starts. If you can do the cold starts with kicking, using the electric start for stalls or after a gas/tea/lunch/antiqueing stop then a 1/2 second or so crank should always start it - and a small battery will be fine. The stock 12AH battery should be able to crank it for around 12 minutes from fully charged to dead. (Don't try that; the starter motor is designed for quite low duty cycle and will have melted by around 5 minutes) Even properly maintained batteries show a capacity dropoff with age: a smaller battery will need to be replaced sooner than a larger one because there's less capacity when new.
Next is your riding. City riding will rarely if ever leave a full charge on a 400F battery, the alternator only charges at fairly high RPM and the battery is discharging whenever RPM is below that. With a normal load (no high wattage lighting or power sucking EI unit) if you usually go on longer rides without stops ... AND keep the revs up rather than putting along in top gear ... the battery should usually be close to full charge when you get home. A bigger battery will have more reserve for the next start even in city riding. The more you discharge the battery with the starter, the longer you must ride at higher RPM to recharge.

Battery type makes some difference. Sealed and AGM batteries have similar chemistry and charge requirements to the OEM wet cells, and the charging system is generally compatible. Sealed batteries rarely have the amperage capability to handle a starter motor, most are designed for relatively slow discharge use like emergency lights or UPS units. If a battery has tiny spade lug connections, assume the internal wiring is similarly sized and not made for starter motor amperage. Many AGM batteries are made for starting use.
Lipo and other "modern" chemistry batteries are simply not compatible with our old stock charging systems: sellers that say they are are basically lying to you. Lithium batteries are also dangerous - lead acid batteries fail by leaking explosive gas and acid (not good) but lithium batteries can light up like a road flare (extremely awfully bad). Even electronic regulators designed for lead-acid batteries are consequently incompatible with other batteries. I haven't seen a regulator designed for lithium batteries. Also, Lipo batteries (as well as NiCad and some others) should never be fully discharged (lead acid batteries shouldn't either but the resulting damage isn't crippling). Devices that use them should have circuitry that disconnects the battery before over discharging. It would be easy to accidentally drain a 400F battery, they even feature "parking lights" that will readily completely discharge it.

[AshimotoK0]

Cracking good reply there Dave ... keep 'em coming ! if you strip down a lithium battery from a laptop etc, you can see from  the complexity of the charging circuitry that Lithium Ion charging  is somewhat complex. You a right that they shouldn't be deeply discharged, which is why power tools just stop dead, once a certain discharge point has been reached.

[Nurse Julie]

Good morning expert Geeks. I didn't understand a single word of that. My option would be to do away with the battery and bump start it 

[AshimotoK0]

Good morning expert Geeks. I didn't understand a single word of that. My option would be to do away with the battery and bump start it 

What do you mean Geeks Julie? ... We are 'anoraks'. There's a difference y'now

[MCTID]

Ha....Iv'e seen you Nurses trying to kick start a Hospital bed.

Hang on.......... my Wife just informed me that you use the foot pedals to raise the bed....

[Nurse Julie]

Good morning expert Geeks. I didn't understand a single word of that. My option would be to do away with the battery and bump start it 

What do you mean Geeks Julie? ... We are 'anoraks'. There's a difference y'now

To me as a woman of average intelligence Ash, whatever you are, Geek or Anorak, you are fonts of knowledge in areas that I did not know even existed

[Nurse Julie]

Ha....Iv'e seen you Nurses trying to kick start a Hospital bed.

Hang on.......... my Wife just informed me that you use the foot pedals to raise the bed....

We push buttons to raise the beds as all electric and kick start the patients these days, otherwise they would never go home !!!!

[MikeSB6]

Hello,
  thanks for the replies, it'll give me something to think about (a lot!)

    Cheers, MikeJ

[Drew400]

Hi Mike, good question resulting in useful learning from the kind souls who answered.

I use an 'intelligent charger" on the batteries of all my vehicles, modern and old. Having read above, I have no doubt that my infrequent use and limited distances/revs would disable my 400's battery in no time.

So your question has generated affirmation of my approach and may be useful for you too.

I use CTek/Yuasa chargers (they are both from the same manufacturer).

Cheers, D.

[ST1100]

I've made excellent experiences with the Optimate chargers/maintainers over the years.
Recovered standard Yuasa's from like 3V and such, without any issues...