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Lithium battery

PostPosted: Sat Mar 12, 2016 8:15 pm
by Crusty
Think my battery is playing up!
Do I replace like for like or upgrade
What about Lithium battery, add lightness and all that,
Just interested

Re: Lithium battery

PostPosted: Sun Mar 13, 2016 10:16 am
by stevebroad
A lithium battery to run an Elan will cost around ?220 from the likes of Antigravity Batteries in Southend. I have one and it weighs 980gms! The battery clamp will weigh more :-)

However, you will need to get a battery charger designed for lithium batteries as standard chargers will kill them. They are around ?50 for a decent one. They also need more care than lead/acid and mustn't be discharged as that will also kill them.

Image

Re: Lithium battery

PostPosted: Sun Mar 13, 2016 11:09 am
by gherlt
I would also mention that there are different kind of Lithium batteries available, Li-Ion and LiFePo4, the latter "do not explode".
And in both flavours you can get batteries with or without battery managment systems (BMS), the latter obvoiously being cheaper. The BMS protects the battery from "High Amps", "High Volts" and shuts off at "Low Volts".
Downside of the BMS is also that it allows only a maximum of ampere, so you need to check if it delivers what you need for the starter...

Batteries without BMS give all Amps they can deliver, but if you expose it to high Volts or drain it below a certain voltage, you buy a new one...

Re: Lithium battery

PostPosted: Sun Mar 13, 2016 12:12 pm
by stevebroad
Yup, there are not a fit and forget item.

Re: Lithium battery

PostPosted: Sun Mar 13, 2016 5:15 pm
by msd1107
Saving 30+ lbs is a suitable reason to make the change.

With the lighter weight and smaller size, the battery can be relocated up close to the starter for less voltage drop during starting. Use a geared starter for less current draw and faster cranking speed.

Check the maximum current draw of the starter and if it exceeds the maximum allowed by the BMS, do not use the BMS. The original generator had a safe rate of charging. If you convert to an alternator, get the smallest one possible to limit the maximum recharge rate to maximize the life of the battery. Many modern alternators have a charge rate of 40+ amps, and it is easy to get 80 or 100+ amps, far in excess of the needs of the battery. In this case, more is definitely not better.

David
1968 36/7988

Re: Lithium battery

PostPosted: Sun Mar 13, 2016 8:45 pm
by stevebroad
Plus the extra weight saving of a shorter battery cable :-)

The charging issue is something I hadn't thought about. I will discuss with Antigravity tomorrow.

Re: Lithium battery

PostPosted: Mon Mar 14, 2016 12:36 pm
by Crusty
Interesting stuff
as i am still on a dynamo
I thought i would enquire as my new li ion tools for work are amazing

Re: Lithium battery

PostPosted: Mon Mar 14, 2016 1:57 pm
by denicholls2
So, you save on battery weight, but then need to add a box to limit current so your Elan doesn't become a puddle when the battery becomes a light source (examine photos of hoverboard burnups and then consider the much greater potential of a high-amp battery)

Seems to me that if you want to run one, you want one capable of meeting all of your battery needs for an outing without re-supply. Then get real weight savings by removing the dynamo/alternator.

Back in the day when I couldn't afford a replacement and my dynamo wouldn't dynamize, I recharged overnight and ran during the day/night. Always got me home, planning sometimes required, headlights occasionally dim on arrival. LED's would help here...

Re: Lithium battery

PostPosted: Mon Mar 14, 2016 6:10 pm
by stevebroad
denicholls2 wrote:So, you save on battery weight, but then need to add a box to limit current so your Elan doesn't become a puddle when the battery becomes a light source (examine photos of hoverboard burnups and then consider the much greater potential of a high-amp battery)

Seems to me that if you want to run one, you want one capable of meeting all of your battery needs for an outing without re-supply. Then get real weight savings by removing the dynamo/alternator.

Back in the day when I couldn't afford a replacement and my dynamo wouldn't dynamize, I recharged overnight and ran during the day/night. Always got me home, planning sometimes required, headlights occasionally dim on arrival. LED's would help here...


Not a good idea with Lithium batteries as when they drop below a certain voltage they die, permanently.