Topic: Upgrading to Lithium battery. What do I need to know?

[tlbranth]

A friend used an expensive lithium battery in his custom VW bus. He's having nothing but trouble with it. I have 4 bikes. I insist on good tires, good brakes and good batteries. For the last I buy only Yuasa (same as Interstate) AGM batteries. They've never let me down.

[scottly]

I've been using LiFe batteries since 2011, including the first three relays.
1) LiFe batteries are much lighter than lead acid batteries.
2) LiFe batteries are much more expensive than lead acid batteries for the same capacity.
3) LiFe batteries do not self discharge like lead acid, so do not require maintenance charging.
4) LiFe batteries prefer having a maximum charging voltage of 14.4V; the original Rick's regulator didn't cut off the voltage until something like 14.9V, and I've personally seen spikes as high as 15.5+V with a stock mechanical regulator with an LiFe battery. The Lithium specific Rick's reg claims to limit the voltage to 14.0V, +/- .2V. Shorai recommends 13.9-14.4 V. 
Bottom line is if you don't know what you are doing, you can waste a lot of money ruining expensive batteries, with little to no gain.   

[Spanner 1]

See, the charging system in our old SOHC4 bikes is designed around a lead-acid battery. Works very well as that ( for 50 years for some bikes). Change any of the key components for new fangled; your on your own

[maxheadflow]

First off a Zener diode is not a really good way to regulate the system.   The ones used are not that accurate and have a finite impedance. It would be better to use an amplifier and another shunting device like a transistor or mosfet. Use a precision zener as a voltage reference only.

So, I read the "poor mans" Voltage Regulator (zener diode) is no longer ideal.

What was you going to use for your comparator circuit in your Voltage regulator?
Would not you need to compare the desirable regulated output to the reference voltage and adjust the pass element accordingly to maintain regulation?

It's been a while on component selection.  Certain zeners have pretty low drift and output but it would probably better to find a good voltage reference device.  LT, Maxim, Analog devices are good.  A low input offset rail to rail operational amplifier with some drive and a good mosfet. Say a P channel.  A few precision resistors to set voltage, plus a few more for gain and caps for loop filtering.    With that, one could clamp output voltage much better than a Zener.

A 10 watt zener is going to have 3 ohms of impedance.  That means a 1 amp variation is going to cause a 3 volt variation in voltage.  The output impedance of a mosfet with closed loop controls is going to be less than a few tenths volt over say 10 amps of current range. Will need a big heat sink if you plan on going it that way with that current variation.

Most older systems balanced the alternator output so that less current needed dumping.

[maxheadflow]

I've been using LiFe batteries since 2011, including the first three relays.
1) LiFe batteries are much lighter than lead acid batteries.
2) LiFe batteries are much more expensive than lead acid batteries for the same capacity.
3) LiFe batteries do not self discharge like lead acid, so do not require maintenance charging.
4) LiFe batteries prefer having a maximum charging voltage of 14.4V; the original Rick's regulator didn't cut off the voltage until something like 14.9V, and I've personally seen spikes as high as 15.5+V with a stock mechanical regulator with an LiFe battery. The Lithium specific Rick's reg claims to limit the voltage to 14.0V, +/- .2V. Shorai recommends 13.9-14.4 V. 
Bottom line is if you don't know what you are doing, you can waste a lot of money ruining expensive batteries, with little to no gain.

I agree with this 100%..   Unless you can get a regulator specifically compatible with LI, stay with Lead acid / AGM.  Even AGM batteries can have issues with older charging systems.   IMO unless you really need the weight saving the only other issue to have LI is for more CCAs.  I own 2 bikes with LI batteries and they only reason is that the LI battery can turn the motor over and it fits in the compartment provided.

[scottly]

It's been a while on component selection.  Certain zeners have pretty low drift and output but it would probably better to find a good voltage reference device.  LT, Maxim, Analog devices are good.  A low input offset rail to rail operational amplifier with some drive and a good mosfet. Say a P channel.  A few precision resistors to set voltage, plus a few more for gain and caps for loop filtering.    With that, one could clamp output voltage much better than a Zener.

A 10 watt zener is going to have 3 ohms of impedance.  That means a 1 amp variation is going to cause a 3 volt variation in voltage.  The output impedance of a mosfet with closed loop controls is going to be less than a few tenths volt over say 10 amps of current range. Will need a big heat sink if you plan on going it that way with that current variation.

Most older systems balanced the alternator output so that less current needed dumping.

What the F**K are you talking about?? Do you think you can design a better regulator for our excited field charging systems than what is already available?? By the way, shunt regulators are normally used with permanent magnet alternators, not excited field.  

[maxheadflow]

It's been a while on component selection.  Certain zeners have pretty low drift and output but it would probably better to find a good voltage reference device.  LT, Maxim, Analog devices are good.  A low input offset rail to rail operational amplifier with some drive and a good mosfet. Say a P channel.  A few precision resistors to set voltage, plus a few more for gain and caps for loop filtering.    With that, one could clamp output voltage much better than a Zener.

A 10 watt zener is going to have 3 ohms of impedance.  That means a 1 amp variation is going to cause a 3 volt variation in voltage.  The output impedance of a mosfet with closed loop controls is going to be less than a few tenths volt over say 10 amps of current range. Will need a big heat sink if you plan on going it that way with that current variation.

Most older systems balanced the alternator output so that less current needed dumping.

What the F**K are you talking about?? Do you think you can design a better regulator for our excited field charging systems than what is already available?? By the way, shunt regulators are normally used with permanent magnet alternators, not excited field.

I was discussing a better zener. That is all. I'll agree with the rest.  BTW, shunt regulators generally use SCRs to short the alternator coils out as it reduces heat.  Field excited would be much easier.

[dave500]

Some newer type of regulator- rectifiers run full constantly, burn the overvoltage to ground to keep voltage within the range.
That will produce a lot of heat and stress the alternator windings. Horrible design!
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permanent magnet types do this,never use one on an electro magnetic field type,two different systems.

[Greaser Greg]

I just talked to someone at rick's motor sports about their reg rec combos they make and they are designed to work like the stock systems for the bikes they go on.

[maxheadflow]

I just talked to someone at rick's motor sports about their reg rec combos they make and they are designed to work like the stock systems for the bikes they go on.

Since they use the field coil to drive output and are likely solid state, it's my bet that they work better than the old regulator as they would be able to control current continuously instead of using 3 steps.

[bryanj]

They will controll the charge better when battery gets more charged but the laws or physics say they can not improve charging at low charge and revs as all you can do is put all available battery voltage into the field coil then the faster the rotor goes the more you get out, the original mechanical reg does that anyway

[dave500]

I use a bosch reg,itll idle at 13 volts.

[maxheadflow]

They will controll the charge better when battery gets more charged but the laws or physics say they can not improve charging at low charge and revs as all you can do is put all available battery voltage into the field coil then the faster the rotor goes the more you get out, the original mechanical reg does that anyway

I assume you mean by simple electrical analysis that the relay in the regulator is closed at low engine speeds so the charging is set to max. This is correct but at what RPM/Voltage does the relay start to switch?  If the number is too low, say the spring in the relay is worn or weak, it will begin to cut back charge rate early.

[bryanj]

Norelay or any other mechanical parts its all done by electronic trickery!

[Greaser Greg]

I just talked to someone at rick's motor sports about their reg rec combos they make and they are designed to work like the stock systems for the bikes they go on.

I called to ask about the shunting to ground causing stress and heat to a generator bringing failure. He said if a system is designed to do that, theirs will, too. For an excited field coil with brushes, it will not.

[Ll_lis]

Lithium Batteries operate at a really high voltage, not good for old bikes with primitive charging systems. They do not like to be under 13.5 volts even when stored as opposed to every other battery that rests at around 12.6.  They also are susceptible to issues when the weather is cooler.


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[Vintageguy]

I put a gel cell in my '78cb750f and love it. Keeps a good charge for about 2 years, and dosen't leak/seep/weep/drip all that nasty crap into my box/frame. Totally sold on it. Just sayin' and I'm sure someone will tell me I'm wrong.

[rotortiller]

Lipos don't like to be flattened, it causes damage. If you have a bike that requires routine post ride battery charging  either from an undersized alternator or one run at low rpm  you are asking for a lipo failure. It has nothing to do with the regulator being stock or a 'ricks magic reg' to the rescue. Good lipos have internal balancing electronics.

[maxheadflow]

Do you mean like this?

[minimo]

I had to relocate my battery and ran into space and mounting constraints. Ended up mounting a Shorai LFX14A2-BS12 in conjunction with a Rick’s reg/rec (older pre-LiFePo version) and been running fine for over a couple of years now and I love it - no issues. Especially love that I can mount it any which way I want and it’s small and lightweight. It is true that you want to maintain at least a 12.4V and not want to flatline them.
I’ve had to go through a couple of these batteries to learn that once you take them below that threshold, it’s difficult to bring them back. But, I still love my Shorai LiFePo. Great customer service too.


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[scottly]

A friend used an expensive lithium battery in his custom VW bus.

Hey Terry, I have a slightly customized VW bus, but I never bothered with a lithium battery for it.
 

[Tracksnblades1]

A friend used an expensive lithium battery in his custom VW bus.

Hey Terry, I have a slightly customized VW bus, but I never bothered with a lithium battery for it.
 

Bet you had to leave a window open for that Mopar....

[tlbranth]

A friend used an expensive lithium battery in his custom VW bus.

Hey Terry, I have a slightly customized VW bus, but I never bothered with a lithium battery for it.
 

Whoa!

[Redline it]

So far, lithium batteries have downed a jetliner and recently sank a 95 foot liveaboard dive boat.lithium is some mean batteries.

[Pielz]

For what it's worth my k7 is running with a cheap little 20 dollar no-name reg/rec from Amazon and it's been absolutely awesome. No excess heat, voltages are great. Cleaned my connections from the alternator to the reg and it cleared up every bit of weak charge. I can run the starter for hours it seems haha when before it died after a handful of start attempts.