Antigravity Batteries. 4 or 8 cell?

[Ezetman]

Is this battery too small (4 celll Antigravity Battery)? Hell, is an 8 cell too small?
They also detail in their specs that bikes mid 80's or older should upgrade to a modern voltage regulator.
Has any one done the conversion to these Lithium batteries before, how'd it work out?

I laid out the wiring harness last night under my seat and I have limited space for the battery as you can see so the 4 cell would prob make it easier for me to fit but I want to make sure it won't be too hard to troubleshoot any other issues that may come up from switching batteries.

 

[16VGTIDave]

Remove the e-start if installed and the 4 cell will be fine. With a modern regulator, of course. Just don't leave the ignition or lights on without the bike running.

 

[Ezetman]

Hmm I don't want to do away with the electric start. Don't get me wrong, I like having the ability to kick start it and I prob shouldn't be admitting to this in this forum but I don't find it appealing to have to kick start the bike up every time.

Is changing the regulator as straight forward as just buying a new aftermarket one?

 

[BBS360]

I'm also curious about what constitutes a "modern" regulator.

For our bikes I think the ultimate solution, if it works, would be to install a modern series voltage regulator/rectifier combo (Shindengen SH775?) with an external adjustable field coil controlling voltage regulator.
It'd eliminate any risk of overcharging the lithium battery while still providing the field coil excitation that "modern" regulators do not do
I don't believe anyone has yet tried it but I've been gathering information to possibly try it on my SJ.

 

[Ezetman]

I'm also curious about what constitutes a "modern" regulator.

For our bikes I think the ultimate solution, if it works, would be to install a modern series voltage regulator/rectifier combo (Shindengen SH775?) with an external adjustable field coil controlling voltage regulator.
It'd eliminate any risk of overcharging the lithium battery while still providing the field coil excitation that "modern" regulators do not do
I don't believe anyone has yet tried it but I've been gathering information to possibly try it on my SJ.

Hey BBS I found through another thread in the forum that someone linked Ricks Motor electrics which sells new regulators/rectifiers which seem to be replicas of the stock ones but I am unsure if they have any new modern components that make them superior to our stock ones or perhaps compatible with Lithium batteries. I'm probably just going to wing it with the new battery and the stock regulator I have and then start troubleshooting. Despite all the research I do, I seem to only learn once I get into it.

 

[BBS360]

I know a couple members have had trouble getting the Ricks reg/recs working: http://www.xs400.com/threads/regulator-rectifier-help.15616/#post-160002

Just had a look at their site again and it looks like their units must be functionally the same as the OEM ones. They might use slightly more efficient components than the 30+ year old units but in the end it's just a three phase rectifier and a field coil controller regulator. Nothing actually regulates the electricity once it comes out of the alternator.
If they had any of the circuitry that modern regulators have it'd definitely be a selling feature they'd mention, and they'd probably charge twice as much.

You can put a lithium battery in the bike and it'll work fine for a while but in the long-term you'll be exposing it to abuse that they are not meant to see.
At the very least I'd go with something like the VR3-U at the bottom of this page: http://www.oregonmotorcycleparts.com/vregulators.html
Or maybe this: http://www.mgcycle.com/index.php?main_page=product_info&cPath=37_161&products_id=1110
They're both adjustable so you could tune it down slightly for the lower lithium charge voltage.

Adding a modern series-type reg/rec in addition to an adjustable regulator would probably be even better, but as mentioned I don't think anyone has tried it yet.
Once I finally get my '82 running again and actually start a project on it I might give it a try.

 

[cosworth]

I had a 4 cell on my SR250 cafe. It spun over just fine. Even in a Canadian winter.

Installing one on a 400 would be ok as long and you ride it often and it starts easy.

 

[Jones]

Iv got an 8 cell in my chop. I can only kick start and its not charging well. So i do kick only and charge it nightly.

 

[maydaverave]

I used the 4 cell antigravity. It worked fine for a while but i was and am having problems with my charging system. The problem with lithium polymer batteries is if they go dead they stay dead or puff up and if they do that can catch on fire. The antigravity battery isn't any better than a standard rc lipo battery but five times as exspensive. I'm running a 4 cell turnigy graphene battery from hobby king. These batteries are cheaper than the antigravity but much more powerful, last three times as long, and are extremely resistant to abuse. I have completely discharged my graphene battery about five times with no bad effects. The antigravity battery puffed up the first time.

 

[maydaverave]

I'm looking for a mosfet regulator rectifier but can't seem to find one with wires that match the xs400.

 

[BBS360]

You won't.
MOSFETs are used in modern regulators to achieve phase control voltage regulation. By definition they don't need the additional wires that our bikes need because they don't regulate voltage the way ours do.

You could use that type of regulator/rectifier but you'd have to power and control the field coil somehow, either by keeping the stock regulator or installing an aftermarket one.

Again, as a disclaimer, I haven't seen anyone post about running a modern regulator/rectifier on an xs400 but with a field coil regulator also installed it should be a rock-solid setup.

Using a properly selected MOSFET/SCR regulator/rectifier should greatly reduce the chance of destroying a lithium battery like you described.
I'd recommend a good series regulator rather than a shunt type. It will run cooler and regulate better.
The Shindengen SH775 or SH847 would be be good options.Their setpoint can still vary above the ideal 14.2V for lithium batteries but it's still much better than the stock setup.
Kept cool they should greatly prolong the life of lithium batteries.

 

[maydaverave]

So with the mosfet i would hook it up to the phase wires, run the power to the battery, and I'm assuming a ground. Then i could leave the stock regulator wired to the green, black, and brown, wires?

 

[BBS360]

That's what I've been thinking about trying.
Hate to recommend something I haven't tried personally but I can't see why it wouldn't work, adding that extra protection for aftermarket batteries.

It could be a drop-in replacement of the stock rectifier if you can get the right connector on the new reg/rec.

 

[maydaverave]

I actually already pulled the trigger yesterday and ordered a mosfet regulator rectifier thats supposed to be universal. It's from ricks motorsports and supposedly is compatible with any three phase charging system. Time will tell.

 

[maydaverave]

So the green wire powers the field coil. Turns it on and off as needed to produce power? But a mosfet rectifier can get rid of excess power without overheating? So couldn't i just run a hot wire to the green wire? What am i missing?

 

[maydaverave]

Could i just run a hot wire from a circuit that is only hot when the bike is on? So it's not powered when the bike is off? Couldn't i just wire the green and brown wire together?

 

[BBS360]

You're not missing anything.
Doing that essential simulates how the MOSFET/shunt regulator normally functions.

It should work, but I'd caution against it. The field coil will be running at 100% capacity 100% of the time.
That's 3.5A or about 50W of energy being used in the field coil all the time. Normally this gets turned down to a minimum setting when the battery is fully charged (about 15W on my xs360).

Because it's a MOSFET/shunt type you'll also be saturating the stator all the time. Counter-intuitively it also means that when your battery is fully charged it's doing the most work and generating the most heat, shunting excess power to ground.

I'd expect it to work pretty well for a while but you can count on burning out the field coil or stator eventually.

Keeping the stock voltage regulator will significantly reduce the load on the field coil when the battery is fully charged
The new regulator will still saturate the stator but with the reduced current in the field coil that saturation current will be lower and generate less heat.
It'll prolong the life of the stator, field coil, regulator, and the battery...

Reducing heat in the new regulator is especially important for your lithium battery.
The hotter the MOSFET regulator gets the poorer its regulating ability gets. It generates the most heat when the battery is fully charged since it's shunting the excess power to ground through itself but that's also exactly when you want the regulator to be regulating to the best of its abilities to prevent overcharging the lithium battery.

As a side note, anyone doing the PMA mod would have to change to your type of regulator so it's been done but they'd no longer have a field coil to worry about.

 

[maydaverave]

The point of the mosfets is to handle excess current for much larger bikes without wearing out. The lithium graphene battery can handle more volts than a functional regulator will put out. Once it's charged to the charging voltage the current should just pass through the battery and since the graphene batteries have nearly zero internal resistance this shouldn't produce any heat. I suppose my main concern would be the feild coil and stator. I'm worried since the stock regulator rectifier isn't charging at rpms less than five thousand that keeping the stock regulator will continue the same problem.

 

[maydaverave]

I'll probably try both ways. Check for excessive heat in the battery and regulator rectifier. With the addition of stock regulator check the charging voltage at various rpms.

 

[maydaverave]

50 watts of power in the feild coil doesn't mean 50 watts of heat. I'm assuming most of that is turned into a magnetic field and only the current lost in resistance turns into heat. A fraction of 50 watts isn't much heat.