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Cars still use the lead acid battery technology invented by Gaston Planté in 1859. It works and proven reliability but power density is low and only about 30% of the headline capacity (amp-hours) is usefully usable. They also don't like vibration, hate being left unused for months and generally don't cope with abuse. In very cold weather you get one chance to engine start then the battery goes dead. They are also highly toxic internally.
Today we have lithium batteries to consider.
Lithium Polymer LiPO is a wet cell with high energy density (way beyond lead acid) used on phones and power tools. But they are very fussy about how they are charged and will catch fire if not done right!!!
LiFePo4 is a dry cell technology, not as energy dense as a phone battery but still a lot more useful than a lead acid. And old batteries are non toxic.
My bike (BMW 1200 twin) used to have a 14AH lead acid which weighed 5kg. It now has a 4 Amp-Hour JMT LiFePo4 battery that weighs less than 1kg. It looks far too small (14 v 4) but the lithium can deliver all of its capacity at full current whereas a lead acid can only deliver 30% at full power.
Run a lead acid too flat and it wont recover, though sometimes a special charger can rescue it. However, lead acid is tolerant to over voltage charging at least for short periods.
Run a lithium dead flat and you have an expensive brick. Charging at more than 15.5V will do the same. Fortunately, all lithium starter batteries have electronic circuits that prevent over charging or over discharging.
Anyhow, I had left the bike unused for too long and found the battery dead flat. I mean, nothing on the test button. One light (of three) = low. All three = full. This could well be knackered.
Not having an ordinary car charger, I started the car engine and connected the lithium in parallel to the car battery then disconnected the car battery earth clamp.
The multimeter showed 1.3 amps was flowing. I left it running for an hour and crossed fingers. LiFePo batteries are happy with high charge rates so no worries - if the charge holds.
The test button now showed three lights so the battery was put back on the bike and those two 600cc pistons were flung back and forth no problem. The bike starts. Woo Hoo!
Thank you electronic protection.
The little lithium is just as happy to start the car, but 4AH is just not enough reserve for cold starts when everything is on full blast and the steering is making heavy demands. An 8AH or 12AH would be needed and that size is still very expensive.
Things are changing. Lithiums have a longer operating life than lead acid and are more tolerant of abuse. Costs are coming down and they are a straight swap.
Today we have lithium batteries to consider.
Lithium Polymer LiPO is a wet cell with high energy density (way beyond lead acid) used on phones and power tools. But they are very fussy about how they are charged and will catch fire if not done right!!!
LiFePo4 is a dry cell technology, not as energy dense as a phone battery but still a lot more useful than a lead acid. And old batteries are non toxic.
My bike (BMW 1200 twin) used to have a 14AH lead acid which weighed 5kg. It now has a 4 Amp-Hour JMT LiFePo4 battery that weighs less than 1kg. It looks far too small (14 v 4) but the lithium can deliver all of its capacity at full current whereas a lead acid can only deliver 30% at full power.
Run a lead acid too flat and it wont recover, though sometimes a special charger can rescue it. However, lead acid is tolerant to over voltage charging at least for short periods.
Run a lithium dead flat and you have an expensive brick. Charging at more than 15.5V will do the same. Fortunately, all lithium starter batteries have electronic circuits that prevent over charging or over discharging.
Anyhow, I had left the bike unused for too long and found the battery dead flat. I mean, nothing on the test button. One light (of three) = low. All three = full. This could well be knackered.
Not having an ordinary car charger, I started the car engine and connected the lithium in parallel to the car battery then disconnected the car battery earth clamp.
The multimeter showed 1.3 amps was flowing. I left it running for an hour and crossed fingers. LiFePo batteries are happy with high charge rates so no worries - if the charge holds.
The test button now showed three lights so the battery was put back on the bike and those two 600cc pistons were flung back and forth no problem. The bike starts. Woo Hoo!
Thank you electronic protection.
The little lithium is just as happy to start the car, but 4AH is just not enough reserve for cold starts when everything is on full blast and the steering is making heavy demands. An 8AH or 12AH would be needed and that size is still very expensive.
Things are changing. Lithiums have a longer operating life than lead acid and are more tolerant of abuse. Costs are coming down and they are a straight swap.
