Adding lithium battery

[lamdar]

I’m planning to add a lithium battery (LiFePo4) to my setup. I currently have a single lead acid battery charged by a questionable dynastart and 50W solar panel through a PWM. I’m thinking about either adding an 280ah lithium to feed all the auxiliary devices, or simply replacing the lead acid battery with the lithium (the maximum power draw is 200A for a few seconds for the dynastart) to use for everything. I’ve read that lithium batteries can’t be used for engine start. However I don’t understand why given that the current draw is within the limit of the battery. It would be much simpler to replace the lead battery with a large enough lithium. And if I add lithium side by side with the lead acid, what’s the best way to set this up? Can I feed two batteries with a single solar panel and two regulators? ( one PWM and one mppt)

 

[ctva]

Have a look at the Renogy DCDC with MPPT. Simple setup and keeps the Lead Acid for the engine. I’ve use this system for two years.

 

[Stemar]

Have a look at the Renogy DCDC with MPPT. Simple setup and keeps the Lead Acid for the engine. I’ve use this system for two years.

If you've got the space for it, extra capacity is always a good thing, and with a twin battery setup, your LA starter battery will always be fully charged, no matter how far you discharge the LiFePO domestic.

On my previous boat, we had a similar setup, but a lead acid domestic battery. 40w of solar kept up with our use (no fridge) on sunny days, but a few cloudy days or a night trip would run things down a bit, so a separate, fully charged, starter battery was very reassuring.

 

[shanemax]

You will notice that there are no car manufactures fitting lithium as starter batteries. This is because in cold weather or in the tropics they do not work very well and the battery control unit will shut the whole battery down if it gets too cold, ( i believe
minus 10c which is half the world in winter) or plus 40c (which is half the world in the summer.} Lithium is still an imperfect science which is why companies are investing billions on a replacement type.

 

[PaulRainbow]

You will notice that there are no car manufactures fitting lithium as starter batteries. This is because in cold weather or in the tropics they do not work very well and the battery control unit will shut the whole battery down if it gets too cold, ( i believe
minus 10c which is half the world in winter) or plus 40c (which is half the world in the summer.} Lithium is still an imperfect science which is why companies are investing billions on a replacement type.

So how about electric cars ?

 

[fredrussell]

I’ve read that lithium batteries can’t be used for engine start. However I don’t understand why given that the current draw is within the limit of the battery.

lithium batteries can indeed start motors. The Renogy 100a/h LiFePo I bought the other day will chuck out 300 amps for 5 seconds before the BMS steps in. Most small boat engines of 3 cylinders or less will use less than 300 amps to turn over. Obviously if your engine takes longer than that to start then it’s less than ideal. However, there are also LiFePo batteries that are designed with engine starting in mind and will chuck out muchos ampage for longer periods.

 

[Minerva]

So how about electric cars ?

Remember the toy cars you had as a kid - you pulled them back and they scooted across the floor? Clearly teslas’ are just a jumbo version of this with a big coil - when you plug them in it just winds the coil. Duh

 

[shanemax]

So how about electric cars ?

They have an internal heater to bring the batteries up to temperature so they will accept a charge in very cold weather.

 

[shanemax]

Oh and nice to see you are about today.

 

[PaulRainbow]

They have an internal heater to bring the batteries up to temperature so they will accept a charge in very cold weather.

LifePO4 batteries for cold climate installations are fitted with a heat mat beneath the batteries, controlled by the BMS.

 

[PaulRainbow]

Oh and nice to see you are about today.

Why wouldn't i be ?

 

[jakew009]

You will notice that there are no car manufactures fitting lithium as starter batteries. This is because in cold weather or in the tropics they do not work very well and the battery control unit will shut the whole battery down if it gets too cold, ( i believe
minus 10c which is half the world in winter) or plus 40c (which is half the world in the summer.} Lithium is still an imperfect science which is why companies are investing billions on a replacement type.

Lots of inaccuracies in this post.

Virtually every BMS will allow discharge down to -20 Celsius.
It’s very unlikely your battery in a boat installed in a normal way would ever get that cold (and that’s my practical experience from thousands of them in less hospitable places than boats).

Charging below 5 degrees is generally prohibited but most now have built in heaters to allow charging at any temperature.

I’ve never seen a battery that cuts out at 40 Celsius, normally they are set to 60 degrees. If your battery is at more than 60 degrees something is dangerously wrong.

There are valid reasons for not fitting lfp (can’t be bothered, don’t want to learn, need only very small leisure battery capacity) but for everyone else lfp blows lead out of the water now from a price and performance point of view.

 

[PaulRainbow]

lithium batteries can indeed start motors. The Renogy 100a/h LiFePo I bought the other day will chuck out 300 amps for 5 seconds before the BMS steps in. Most small boat engines of 3 cylinders or less will use less than 300 amps to turn over. Obviously if your engine takes longer than that to start then it’s less than ideal. However, there are also LiFePo batteries that are designed with engine starting in mind and will chuck out muchos ampage for longer periods.

I recently fitted a 314Ah battery and 300A BMS (so capable of delivering a constat 300A) to a Jeanneau with a 4 cylinder Yanmar. Isolating the LA starter battery and using the emergency parallel switch from the previous setup the engine starts perfectly.

 

[PaulRainbow]

LiFePo4 batteries for motorsport and performance road cars. Next-day delivery!

 

[Baggywrinkle]

.... lithium starter batteries will be used by car manufacturers as soon as the cost difference between Li and LA disappears. I say this as someone involved in the evaluation by a major car manufacturer.

PS we are talking about total cost within the offered warranty period, as well as CO2/energy savings due to weight reduction.

 

[billcole]

LiFePo4 batteries for motorsport and performance road cars. Next-day delivery!

Lithium starter batteries have been available for motorbikes for some time now

You will notice that there are no car manufactures fitting lithium as starter batteries. This is because in cold weather or in the tropics they do not work very well and the battery control unit will shut the whole battery down if it gets too cold, ( i believe
minus 10c which is half the world in winter) or plus 40c (which is half the world in the summer.} Lithium is still an imperfect science which is why companies are investing billions on a replacement type.

Lithium starter batteries have been available for motorbikes for some time now, liked for their light weight and all those emergency starter battery packs on sale are lithium powered.

 

[shanemax]

Lots of inaccuracies in this post.

Virtually every BMS will allow discharge down to -20 Celsius.
It’s very unlikely your battery in a boat installed in a normal way would ever get that cold (and that’s my practical experience from thousands of them in less hospitable places than boats).

Charging below 5 degrees is generally prohibited but most now have built in heaters to allow charging at any temperature.

I’ve never seen a battery that cuts out at 40 Celsius, normally they are set to 60 degrees. If your battery is at more than 60 degrees something is dangerously wrong.

There are valid reasons for not fitting lfp (can’t be bothered, don’t want to learn, need only very small leisure battery capacity) but for everyone else lfp blows lead out of the water now from a price and performance point of view.

Thank you for confirming they are an imperfect science which is why they need heat mats, cannot deal with very cold weather, can off gas if damaged and need a battery control module to try to keep them safe. If damaged a LifePO4 will probably not catch fire but will release a mass of very toxic gas. People once thought Asbestos was a magic product and made every thing from it ????????? Lead in petrol????? CFCs in aerosols ????. Do you wish me to continue.????

 

[shanemax]

Lots of inaccuracies in this post.

Virtually every BMS will allow discharge down to -20 Celsius.
It’s very unlikely your battery in a boat installed in a normal way would ever get that cold (and that’s my practical experience from thousands of them in less hospitable places than boats).

Charging below 5 degrees is generally prohibited but most now have built in heaters to allow charging at any temperature.

I’ve never seen a battery that cuts out at 40 Celsius, normally they are set to 60 degrees. If your battery is at more than 60 degrees something is dangerously wrong.

There are valid reasons for not fitting lfp (can’t be bothered, don’t want to learn, need only very small leisure battery capacity) but for everyone else lfp blows lead out of the water now from a price and performance point of view.

Yes if your battery is at 60c it has been sitting in your black metal car some where in the tropics. On a hot summer day, even in the uk anything black can easily reach that temperature and you know it as we have all experienced taking our hand off something which is very hot that's been in the sun.

 

[shanemax]

lithium batteries can indeed start motors. The Renogy 100a/h LiFePo I bought the other day will chuck out 300 amps for 5 seconds before the BMS steps in. Most small boat engines of 3 cylinders or less will use less than 300 amps to turn over. Obviously if your engine takes longer than that to start then it’s less than ideal. However, there are also LiFePo batteries that are designed with engine starting in mind and will chuck out muchos ampage for longer periods.

Please don't be a politician and not answer the question, never mind your 5 seconds of cranking amps which is a ridiculous statement, why do NO car manufactures fit lithium starter batteries

 

[shanemax]

.... lithium starter batteries will be used by car manufacturers as soon as the cost difference between Li and LA disappears. I say this as someone involved in the evaluation by a major car manufacturer.

PS we are talking about total cost within the offered warranty period, as well as CO2/energy savings due to weight reduction.

So they fit heated seats, heated steering wheel, electric seat controls, air conditioning, electric sliding roof electric windows etc etc ect but they are held back by the cost of Lithium versus Lead, B/S