LIFEPO4 for starting

[bill good]

OK still holding off on putting these on my boat But I have been looking into maybe a 20A/H for starting my 1GMs with a ultra cap of 56F across it. It seems if a large road transport truck can start on 560F then I reason 1/10th should be suitable for 7.5HP. I know the 20A/H batt may even start it on its own but with the cap to take the load & the battery would be providing the energy for the starting cap.

What do my advisers say?



Regards Bill

[Sysunday]

Check http://www.ev-power.eu/
They have "PCM" batteries suitable for starting.
Should work very well

[Pete7]

Why? they are in Czech Republic the OP is in Australia, unless you have a connection to the company after all you have recommended them twice in 3 posts?

Pete

[CharlieJ]

Sysunday:
The link you provided contradicts your statement:

Note: Due to the limitations of the protection circuit module (PCM), these LiFePO4 block 12V batteries may not be suitable for high current traction applications. They cannot be used as starting batteries.

[OceanPlanet]

If RaceCell ever gets these "Nanostart" batts back in production, that would be nice. I supplied some a while back, clients liked them but haven't been able to get any more for about a year...

[bill good]

Update: No ultra caps used Fitted 8 headways 38140S for 12v 24AH. First start drop was 14 down to 11.9 & rose above 12.8 before start cycle was completed & straight up to 14v on startup with the alternator charging. Three more normal starts with much less drop in voltage. Then with the fuel cut off out to prevent the engine starting three cranks of 10secs to take out a fair amount of energy & the engine then fired up with the voltage still above 11volts min. Pretty good. Cost $200.00 Weight less than 3.5kg & half the size of the 55ah LA its replacing.

How safe well google" Headways Punchure.avi" & "Headways lifepo4 cell visisection.lithium iron phosphate.safety testing"

Ultra caps may help in very cold climates to assist but not sure if there would be a cost effective because of the LIFEPO4 having such a low ESR.

Regards Bill

[dansken]

I am considering getting a lifepo4 battery to replace the current lead-acid start battery. The engine is a yanmar 4jh4. A 60 ah (12v) would by sellers specs match the recommendations from yanmar. However, from my experience with my lifepo4 24 v housebank the specs of the lifepo4s are very conservative and i think a 40 ah should do the job. Anyone got any experience with lifepo4's as a starting bat?
Candidate: http://www.ev-power.eu/LiFeYPO4-batt...LP12V40AH.html

[bill good]

Dansken, I am still using the 24A/H on one engine & a 40A/H on the second. Combine both for starting when I remember!! I am using standard unmodified alternators but have a timer to cut off the charge from the alternator as I believe it is advisable to do so once the battery is recharged. I have other circuits added to keep the voltage regulated for the few 12V circuits that need to come off the same power source. (only on the 24A/H at this time.)To keep it within the "KISS" idea do not go for larger alternators as the charge currents can become an issue. The boat installation can need the engine to run much longer than the average car engine for which there are 12V LIFE replacements being offered. Time in service - over 2 yrs on the 24A/H battery & over 18 Mths on the 40A/H. Two 1GM Yanmars

Regards Bill

[dansken]

Thanks Bill for this update. My starting battery is charged from the 24 volt house bank though a charger - my two 24 volt alternators charge the house bank (200 ah LIFEPO4).
I would like the LIFEPO4 starting battery for weight saving, for the low self discharge and easy maintenance (no trickle charge needed).
my question is what size is needed. I know that there are different lithium cells out there - some better suited for fast discharge than others - but these standard ones EV-Power | LiFeYPO4 batteries (12V) shouldn't they do?

[dansken]

and these from your neck of the Woods http://ev-power.com.au/webstore/inde...ry-module.html
Can't find these in Europe.......

[bill good]

40A/H life would be as good or better than a 60A/H lead. The interesting bit is if you look inside the yellow outer case you will find 4 cells strapped together with the usual plates & ties.

Regards

[ardoin]

I'm using 200Ah for a starting batt. I top it off when the main bank (1000Ah) is charging. I works very well even at starting my stubborn Northernlights gen set. I have never drained it below 13.1 volts and it always has plenty of power for the Yanmar. It is also a backup for a few amps should the house bank ever die.

[dansken]

Ardoin, I am considering the option of going as "small" as possible, i.e. the smallest LIFEPO that would consistently start my 4JH4 Yanmar or, do as you did, go larger and call it a start/backup bank. Not sure though that I can justify the price tag for a larger LIFEPO bank not doing much else than cranking the engine ......

[hellosailor]

dansken-
If you find the specs for your engine and starter motor, I would guess the starter motor itself is rated for somewhere between one and two kilowatts of drain. All you need from a starter battery is one that can supply 1-2kW for five or ten seconds for starting then, and it becomes a question of reading battery specs to see how small a battery you can get, which will provide that a "sufficient" number of times. Even a small battery will provide that power once, twice, maybe fifty times. But if you want 200, 500, or 2500 starts...you simply need a bigger battery as your demands on it grow.

Let's say, 2kW for five seconds, that's something like 0.0015 kW-hours of discharge? So if the battery itself can withstand a brief 166-amp draw to do that...the only real question is if your diesel needs prolonged cranking, putting a much greater strain on the battery.

If the lithium folks are right and you can expect 2000-5000 complete discharges from their batteries...then I'd guess even a "tiny" 40AH rated battery probably can do this. But you'd have to run the numbers to explore that. And the BMS would probably cost more than the battery!

(And don't trust my math, there's a reason I'm not allowed to practice math across state lines.<G>)

[bill good]

Dansken, I would recommend you could charge ultracapacitors from 24v for starting & do away with the need for a starting battery given the range of temperatures in your part of the world. This advise assumes your knowledge of the design of the circuits is up to the task!! I did look at using the ultracaps but the cost was not justified given I only will operate in warm tropical waters. I can see the application for ultracaps may even be better in the long run for starting applications than any battery. See application for trucks operating in the frozen north where the starting is purely from ultracaps which have been charged from the normal batteries. (The instantainious current flow of a starter motor may exceed 350A)

Regards