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Dimensionally smaller battery - need advice on cold cranking amp requirements

philosopheriam

philosopheriam

Forum Mentor
Past Site Supporter
Folks,

As part of my 1978 GS1000E custom build/restoration, I am thinking of downsizing the battery to make a bit more room for other stuff. If I dimensionally downsize the battery, it will have fewer CCA's than the original, which is rated around 220.

Does anyone know the amp draw of the starter? Also, I will be running a LED headlight and LED tail light.

What is the lowest CCA battery that is sufficient for these bikes? Just looking for ideas. I understand that it's a smarter idea to have a battery that has a bit more amperage than required as a safety factor.

Thanks!
 
With a 78 can you turn the headlight off for starting? If not, you can do the headlight relay mod which will shut off power to the headlight while the starter is spinning.
 
Does your engine have higher than factory compression ratio?

If so then you will need the cca battery due to starter kickback leading to starter clutch damage. I run a 8 cell Ballstic lithium in my 1000. Not enough cca's even at an advertised 210 cca, however I have an ignition retard lever installed and now my kickback has been eliminated. The battery is still inadequate but it still manages to get the bike started.

Even with the headlight off it is inadequate/weak for starting unless the bike is well tuned and an easy starter.
 
Problem solved:

I went to Batteries & Bulbs today and walked around the store measuring batteries - I found this one, that has 225CCA @ 11.2 Ah. I used several of the Xtreme AGM batteries in other motorcycles and had good luck with them.

Because it is an AGM and can be mounted on it's side, I will do just that - mount it on it's side and shorten the battery box. I know the battery box is from a G model - I'm going to modify it to fit my 78 GS1000E.



My motor has a Wiseco 1100 kit in it with a compression ratio around 10.25:1
 
The Yosh 1085 has 10.5:1, so be careful of kickback.

There is a thread about how to reduce or minimize it.
 
Fjbj40 said:
The Yosh 1085 has 10.5:1, so be careful of kickback.

There is a thread about how to reduce or minimize it.
Click to expand...

I'm thinking about either a manual timing retard or a way to delay the ignition until the motor is spinning fast enough...
 
Forgive me if I didn't read far enough into the aforementioned thread, but did anyone try a relay tied into the oil pressure switch?
 
philosopheriam said:
Forgive me if I didn't read far enough into the aforementioned thread, but did anyone try a relay tied into the oil pressure switch?
Click to expand...

Not that I recall, but that may be an option depending upon your oil pump gears.

modern Headlamp cutouts use a stator wire and you might use that more reliably. The voltage is very proportional to RPM and you can set the threshold easier to what you like.
 
posplayr said:
Not that I recall, but that may be an option depending upon your oil pump gears.

modern Headlamp cutouts use a stator wire and you might use that more reliably. The voltage is very proportional to RPM and you can set the threshold easier to what you like.
Click to expand...

posplayr,

I'm not trying to rehash the aforementioned thread, but for a motor that has stock oil pump gears, what about a delay-on-make relay that has a delay of 1 sec that in turn energizes a relay for the coils? I haven't put together the schematic yet, but having a delay on make timer that is triggered when the oil pressure switch OPENS (because there is oil pressure) then waits an additional 1sec before it energizes the coils. This should be more than enough of a delay to get the motor spinning.
 
You do not have a timing diagram about what you are trying to accomplish; I don't want to guess.

It is also not clear what the operation of the relay is when you have two active inputs. According to the description it will not operate with a +12V input on 87 and a ground on 87a simultaneously.

Note there is implicity 3 states available for each signal +12V, Open and Ground.
 
posplayr said:
You do not have a timing diagram about what you are trying to accomplish; I don't want to guess.

It is also not clear what the operation of the relay is when you have two active inputs. According to the description it will not operate with a +12V input on 87 and a ground on 87a simultaneously.

Note there is implicity 3 states available for each signal +12V, Open and Ground.
Click to expand...

I apologize for the confusion, I should have been more specific.

The goal was to design a basic logic circuit with a timer that energizes the ignition coils 1s after the oil pressure switch opens. The coils will be DE-ENERGIZED under the following conditions:

1. If the oil pressure switch closes due to loss of oil pressure (the engine isn't running OR the engine isn't cranking fast enough to produce sufficient oil pressure to open the oil pressure switch).
2. If the deadman switch is opened
3. If the keyswitch is turned off

If someone attempts to start the bike yet releases the starter button midway, the oil pressure in the engine will drop, close the oil pressure switch, deactivate the timer, the coils will de-energize, and the delay sequence will be restarted when the bike is cranked again.


Detailed Sequence:
1. When the keyswitch is turned ON, power flows to terminal 30 on relay K1. Terminal 86 on K1 is permanently grounded.
2. When the deadman switch is closed, power flows to coil terminal 85 on relay K1 and K2 - at this point K1 will close and allow power to flow to terminal 30 on K2. Closing the deadman also allows power to flow to input terminal 87a on the timer.
3. If the engine is not running, the will be no oil pressure, and the oil pressure switch will be closed, causing coil terminal 86 or relay K2 to be grounded, causing K2 to open, preventing power from flowing to terminal 86 on the timer (this DEACTIVATES THE TIMER). Terminal 87 on the timer will also be grounded.
4. When the bike cranks, oil pressure opens the oil pressure switch causing relay K2 to revert to the NC state, allowing power to flow to terminal 86 on the timer. The open oil pressure switch also removed the ground path from terminal 87 on the timer, and thus, the only active input on the timer is the +12V on terminal 87A. Because the timer has power on terminal 86 and and 87a, it will activate and close in 1s, thus connecting terminal 86 to terminal 30 and allow power to flow to the ignition coil. At this point, the engine has been spinning for however long it takes to create oil pressure + 1s, which should be long enough to prevent kickback once the coils are energized.

The ground from the closed oil pressure switch to terminal 87 on the timer is a "safety" of sorts - if for some reason relay K2 malfunctions and allows power to flow to terminal 86 on the timer in all states, the timer will not activate until the oil pressure switch opens and the ground is removed from terminal 87. Thus, the only active input to the timer is +12V on terminal 87A.
 
Last edited:
Questions:

  1. Does your oil pressure switch open while cranking?
  2. What is the minimum cranking RPM for the switch to open?
  3. Have you resolved the ambiguity in having two simultaneous inputs?
 
I tried the kill switch mod first. While it worked it was not 100% effective. I still had the occasional kick back, because of the low cca of the battery.

I then went with the ignition retard lever and all kick back problems ended, the same result that every person who has done the mod experienced. I still kept the kill switch mod in place but only use the retard lever for starting.

Just my opinion but I think you are way overdoing it with the extra relays. But it is your bike and what you are planning is going to be pretty cool if it works, and it should.

Do us all a favor if it works and add to the "how to prevent starter clutch death" post when you succeed.

By the way, your bike looks awesome!

Cheers
 
Fjbj40 said:
I tried the kill switch mod first. While it worked it was not 100% effective. I still had the occasional kick back, because of the low cca of the battery.
Click to expand...

I think "in a nut shell" you have confirmed the basic solution to kickback. Without changing the timing, you can't really get rid of it, unless you are always spinning very fast.

The issue is firing too early for a given cranking RPM. With a timing retard, the cranking RPM can be much lower and still avoid kickback. Basically there is a maximum ADV as a function of RPM you can have and not get kick back.

If the bike is stock and the battery healthy then you are at something less than the maximum advance. If battery voltage drops (or engine compression increases) and the cranking speed slows, there needs to be a corresponding drop in ADVANCE.

Relays will never solve kickback with low RPM cranking.

I add Dyna 2000 timing info to the other thread :)

http://www.thegsresources.com/_foru...h-Disaster-Modification&p=2234378#post2234378
 
Last edited:
posplayr said:
I think "in a nut shell" you have confirmed the basic solution to kickback. Without changing the timing, you can't really get rid of it, unless you are always spinning very fast.

The issue is firing too early for a given cranking RPM. With a timing retard, the cranking RPM can be much lower and still avoid kickback. Basically there is a maximum ADV as a function of RPM you can have and not get kick back.

If the bike is stock and the battery healthy then you are at something less than the maximum advance. If battery voltage drops (or engine compression increases) and the cranking speed slows, there needs to be a corresponding drop in ADVANCE.

Relays will never solve kickback with low RPM cranking.

I add Dyna 2000 timing info to the other thread :)

http://www.thegsresources.com/_foru...h-Disaster-Modification&p=2234378#post2234378
Click to expand...

Yes, you are correct about timing retard for starting.

In piston powered aircraft there are magnetos used for ignition. Simple very reliable devices that need no battery or voltage input to produce spark. The flaw is the slow cranking speed of the engine for starting. The majority of magnetos use some form of ignition retard for starting. These aircraft, when there is an ignition retard failure are very hard to start, engine basically stops turning if the spark occurs at 20-35 degrees BTDC, which is normal during a running state but not for starting.

I do not know why I did not do this first when I know better:o
 
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