Solar charging

Hi

I am looking into the possibility of charging my 48v battery with solar panels. Is anyone doing this or have any advice?

Considerations:

1. Im wondering if you can charge the battery from the leads that go to the controller instead of using the port where the 240v charger plugs in.

2. Also whether to charge leisure batteries and use those to charge the bike, or just direct charge.

Thanks,

Trevor

Edited April 1, 20224 yr by slowbutsure1936

Hi

 

I am looking into the possibility of charging my 48v battery with solar panels. Is anyone doing this or have any advice?

 

Considerations:

 

1. Im wondering if you can charge the battery from the leads that go to the controller instead of using the port where the 240v charger plugs in.

 

2. Also whether to charge leisure batteries and use those to charge the bike, or just direct charge.

 

Thanks,

 

Trevor

Straightforward if you have a generic type of battery, I.e. not Shimano, Bosch, Yamaha etc..

I have built a solar trailer, which uses lightweight, expensive, high performance panels, but if you mean not taking the panel(s) with you, all you need is a 'normal' glass covered panel, a charge controller, a fuse and a connector to suit your battery.

Probably at least a 100W solar panel, but if you indicate the capacity of your battery (Ah) and what timescale you want to charge in, that can be refined.

Simplest charge controller is the Elejoy mu400sp. About $25 on aliexpress, or a bit more from ebikes.ca if you don't want to wait for far east delivery times.

Straightforward if you have a generic type of battery, I.e. not Shimano, Bosch, Yamaha etc..

 

I have built a solar trailer, which uses lightweight, expensive, high performance panels, but if you mean not taking the panel(s) with you, all you need is a 'normal' glass covered panel, a charge controller, a fuse and a connector to suit your battery.

 

Probably at least a 100W solar panel, but if you indicate the capacity of your battery (Ah) and what timescale you want to charge in, that can be refined.

 

Simplest charge controller is the Elejoy mu400sp. About $25 on aliexpress, or a bit more from ebikes.ca if you don't want to wait for far east delivery times.

Thanks. Its a 48v 20ah battery. The battery does seem to have a specific connection that the AC charge connects to. This is why im wondering if they can be charged from the leads that go from the battery. On a normal battery that would be fine, but I don't know what's inside a LION battery, if there is a diode or something so that a charge only goes one way.

Ideally, id like the battery to charge in one day.

Ive got a 150w panel on my camper van that I am going to take off and use.

Thanks. Its a 48v 20ah battery. The battery does seem to have a specific connection that the AC charge connects to. This is why im wondering if they can be charged from the leads that go from the battery. On a normal battery that would be fine, but I don't know what's inside a LION battery, if there is a diode or something so that a charge only goes one way.

 

Ideally, id like the battery to charge in one day.

 

Ive got a 150w panel on my camper van that I am going to take off and use.

150W is fine, you just need a charge controller. Here is the basic setup, slightly naughty with no external fuse, and here charging via the output port of the battery:

That is 48V 20Ah, Elejoy mu400sp and a 110Wp panel. As simple as that.

The charge controller is vital, as it will limit voltage to prevent overcharging. The Elejoy can be set to any required voltage i.e. 54.6V for 13S 48V.

150W is fine, you just need a charge controller. Here is the basic setup, slightly naughty with no external fuse, and here charging via the output port of the battery:

 

[ATTACH type=full" alt="20220227_150612.jpg]46329[/ATTACH]

 

That is 48V 20Ah, Elejoy mu400sp and a 110Wp panel. As simple as that.

 

The charge controller is vital, as it will limit voltage to prevent overcharging. The Elejoy can be set to any required voltage i.e. 54.6V for 13S 48V.

Thanks. Does your battery have a separate charging port where you plug it into the mains? Or are the wires coming out of your battery connected to the charging port in some way?

Thanks. Does your battery have a separate charging port where you plug it into the mains? Or are the wires coming out of your battery connected to the charging port in some way?

Also, how long does your battery take to charge?

Also, how long does your battery take to charge?

Yes, there is a separate charging port which takes this cable

which is the 54.6V DC output of the mains charger. I tried charging through that connection, which sometimes worked and sometimes did not. I think the BMS does not always accept the charge controller output as a valid charge source, which I think is because I set the charge controller voltage to a bit less than full charge.

I don't have time to fully investigate so I am charging via the output port because (a) it works and (b) I have verified that the charge controller properly limits itself to the voltage it is set to, so will not overcharge. The BMS cannot stop the charge, but it does not need to because the charge controller does. The BMS is still looking after balancing.

150W panel will fully charge your battery on a sunny day, between about April and September. Not on a dull day, and not in one short winter day. Assuming it is facing roughly south and inclined at about 30 degrees.

Yes, there is a separate charging port which takes this cable

 

[ATTACH type=full" alt="20220401_201923.jpg]46330[/ATTACH]

 

which is the 54.6V DC output of the mains charger. I tried charging through that connection, which sometimes worked and sometimes did not. I think the BMS does not always accept the charge controller output as a valid charge source, which I think is because I set the charge controller voltage to a bit less than full charge.

 

I don't have time to fully investigate so I am charging via the output port because (a) it works and (b) I have verified that the charge controller properly limits itself to the voltage it is set to, so will not overcharge. The BMS cannot stop the charge, but it does not need to because the charge controller does. The BMS is still looking after balancing.

 

150W panel will fully charge your battery on a sunny day, between about April and September. Not on a dull day, and not in one short winter day. Assuming it is facing roughly south and inclined at about 30 degrees.

Thats really helpful. Appreciated, thanks.

Yes, there is a separate charging port which takes this cable

 

[ATTACH type=full" alt="20220401_201923.jpg]46330[/ATTACH]

 

which is the 54.6V DC output of the mains charger. I tried charging through that connection, which sometimes worked and sometimes did not. I think the BMS does not always accept the charge controller output as a valid charge source, which I think is because I set the charge controller voltage to a bit less than full charge.

 

I don't have time to fully investigate so I am charging via the output port because (a) it works and (b) I have verified that the charge controller properly limits itself to the voltage it is set to, so will not overcharge. The BMS cannot stop the charge, but it does not need to because the charge controller does. The BMS is still looking after balancing.

 

150W panel will fully charge your battery on a sunny day, between about April and September. Not on a dull day, and not in one short winter day. Assuming it is facing roughly south and inclined at about 30 degrees.

I will be charging from home so I am wondering about the solar panel charging a leisure battery (12v 110ah) and then charging the bike from that. I can then use the bike during the day and charge it over night. Hopefully.

I will be charging from home so I am wondering about the solar panel charging a leisure battery (12v 110ah) and then charging the bike from that. I can then use the bike during the day and charge it over night. Hopefully.

Yes, that way can also be done, using a different type of charge controller, an inverter, and the normal mains charger.

The overall efficiency is somewhat lower, which can be compensated for by a larger solar panel, and the 12V battery needs to be large enough. Lead acid batteries do not like being deeply discharged, no matter what their labels might say. A typical leisure battery will barely last 200 cycles if regularly run below half full.

How often will you need to charge, and how much of your ebike battery capacity each time on average? Is this all year round, or a few weeks of holiday per year? I'll add some numbers later.

It might be that a second ebike battery charging at home whilst you ride with the first might be a better option.

Yes, that way can also be done, using a different type of charge controller, an inverter, and the normal mains charger.

 

The overall efficiency is somewhat lower, which can be compensated for by a larger solar panel, and the 12V battery needs to be large enough. Lead acid batteries do not like being deeply discharged, no matter what their labels might say. A typical leisure battery will barely last 200 cycles if regularly run below half full.

 

How often will you need to charge, and how much of your ebike battery capacity each time on average? Is this all year round, or a few weeks of holiday per year? I'll add some numbers later.

 

It might be that a second ebike battery charging at home whilst you ride with the first might be a better option.

You are seemingly mixing up Leisure and car LA battery types. Leisure (also called deep discharge), are built to handle such situations far better that those for cars.

And remember, the leisure battery is "topped up" within a day or so, should show no ill effects.

Also, with the added benefit of some electronics, to remove them from the load at the correct point, can suffer many, many years of abuse, above and beyond what a car battery can accept.

Please remember, due to their design, Leisure batteries are not good for starting cars for instance, sudden large current draw.....

The following web links appear to be a reasonably accurate descriptiosn of both Car and Lesiure LA Batteries, and tell it far better than I am willing to do:-

https://www.yuasa.co.uk/info/technical/understanding-leisure-batteries/

or this:-

https://www.12voltplanet.co.uk/leisure-battery-guide.html

I hope this helps.

Andy

You are seemingly mixing up Leisure and car LA battery types. Leisure (also called deep discharge), are built to handle such situations far better that those for cars.

And remember, the leisure battery is "topped up" within a day or so, should show no ill effects.

Also, with the added benefit of some electronics, to remove them from the load at the correct point, can suffer many, many years of abuse, above and beyond what a car battery can accept.

Please remember, due to their design, Leisure batteries are not good for starting cars for instance, sudden large current draw.....

The following web links appear to be a reasonably accurate descriptiosn of both Car and Lesiure LA Batteries, and tell it far better than I am willing to do:-

https://www.yuasa.co.uk/info/technical/understanding-leisure-batteries/

or this:-

https://www.12voltplanet.co.uk/leisure-battery-guide.html

I hope this helps.

Andy

Thanks.

Yes, that way can also be done, using a different type of charge controller, an inverter, and the normal mains charger.

 

The overall efficiency is somewhat lower, which can be compensated for by a larger solar panel, and the 12V battery needs to be large enough. Lead acid batteries do not like being deeply discharged, no matter what their labels might say. A typical leisure battery will barely last 200 cycles if regularly run below half full.

 

How often will you need to charge, and how much of your ebike battery capacity each time on average? Is this all year round, or a few weeks of holiday per year? I'll add some numbers later.

 

It might be that a second ebike battery charging at home whilst you ride with the first might be a better option.

A second ebike battery is a great idea.

A second ebike battery is a great idea.

It might be tonight before I can illustrate with numbers. What appeals to me about a second bike battery is that nearly all of the spend is on useful ebike stuff rather than 'enabling works'!

A second ebike battery is a great idea.

Always!

I like a small and a large battery, amps wise.....then you have the best of both worlds!

You also need an e-bike that:-

a) Allows reasonably easy battery change and

b) a battery shape for the spare that can be accomodated in a panier or rucksack or similar.

The best bikes that I have seen for battery changes, are ones that "hinge" in the middle, providing quick access to the battery position, a fairly flat battery shape and size, allowing also a way to transport a much shortened bike in a car, without needing to remove the front wheel!

regards

Andy

You are seemingly mixing up Leisure and car LA battery types. Leisure (also called deep discharge), are built to handle such situations far better that those for cars.

And remember, the leisure battery is "topped up" within a day or so, should show no ill effects.

Also, with the added benefit of some electronics, to remove them from the load at the correct point, can suffer many, many years of abuse, above and beyond what a car battery can accept.

Please remember, due to their design, Leisure batteries are not good for starting cars for instance, sudden large current draw.....

The following web links appear to be a reasonably accurate descriptiosn of both Car and Lesiure LA Batteries, and tell it far better than I am willing to do:-

https://www.yuasa.co.uk/info/technical/understanding-leisure-batteries/

or this:-

https://www.12voltplanet.co.uk/leisure-battery-guide.html

I hope this helps.

Andy

Sorry Andy, but no. I've been around off grid systems for long enough to know what I'm talking about.

Yes, that way can also be done, using a different type of charge controller, an inverter, and the normal mains charger.

 

The overall efficiency is somewhat lower, which can be compensated for by a larger solar panel, and the 12V battery needs to be large enough. Lead acid batteries do not like being deeply discharged, no matter what their labels might say. A typical leisure battery will barely last 200 cycles if regularly run below half full.

 

How often will you need to charge, and how much of your ebike battery capacity each time on average? Is this all year round, or a few weeks of holiday per year? I'll add some numbers later.

 

It might be that a second ebike battery charging at home whilst you ride with the first might be a better option.

Numbers:

Your 48V 20Ah bike battery is around 960Wh, taking the label literally. The charge efficiency of lithium ion is close to 100%, so you need 960Wh plus a bit to allow for the charge controller efficiency from your solar for a full charge from flat. Call it a round 1000Wh, because you don't really want to run it completely flat.

If you need that every day, then you will need about 200W of solar panels: an average day between April and September will give you 4 or 5 Wh for each W of solar panel. A pure blue sky will give more than 10, I.e. 2000Wh from 200W panels, enough to charge two such batteries.

So your 150W panel, if in good working order, is reasonably close to that, so I would start with that and a cheap Elejoy controller for direct charging.

Indirect charging via a lead acid leisure battery, or better, a LiFePO4 lithium battery, needs more panel and a fairly large intermediate battery. I took two 40Ah, 4 cell so 12.8V nominal LiFePO4 buffer batteries with me on my Scotland to Wales ride last October, leaving home with them fully charged. 40Ah x 12.8V is 512Wh each.

I found that using a Sterling Power 150W quasi sine wave inverter and the standard Shimano 1.8A charger, each put only 80% into a flat 418Wh Shimano E8014 battery - just 330Wh or so - before the inverter reached its 10.5V low voltage cutout. That's only 65% combined efficiency from inverter and charger, which roughly equates to 80% efficiency each, which is plausible.

So to go that route, you would need 1.5 times as much solar panel for a start, and then enough buffer battery capacity to match the 1000Wh needed by the bike battery. At 12V, 1000Wh is just over 80Ah, so allowing for inverter and chargef efficiency, 120Ah of usable capacity is required.

As a general rule, going below 50% depth of discharge is not good for the life expectancy of lead acid leisure batteries, so assuming you always have a full leisure battery to begin charging, it needs to be at least 240Ah. However, in the real world, it will not always be full, so either it needs to be yet larger still, or a separate 'low voltage cutoff' device will be needed to protect it from deep discharge. The inverter will keep on going down to a horribly low cutoff, which will trash the leisure battery in a matter of months.

It is also necessary to allow for the poor round trip efficiency of lead acid batteries: you only get back about 70% of the energy used to charge, which translates to needing even larger solar panels. To get the same effect as the direct charging using your existing 150W panel, you would need to increase by 50% for the inverter and charger efficiency losses to 225W, and then by about 50% again to 340W for the round trip losses.

Summary:

Direct charging will do fairly well with your existing 150W panel, and needs only a charge controller and wiring to set up.

Indirect charging needs double or more solar panel, about 240Ah of leisure battery, low voltage cutoff device and suitable inverter.

If you can find another 48V battery that fits the same mount as the first, I think the two batteries, direct charging setup is probably the way to go.

Edited April 2, 20224 yr by matthewslack

Sorry Andy, but no. I've been around off grid systems for long enough to know what I'm talking about.

Sad to say, but they must have been badly designed.

I have a leisure battery, bought in 2004, that I kept in my caravan, which I recently sold with the same battery, still working with little or no capacity loss.

The only possible difference was a charger that I designed and built, to perpetuate the battery for as long as possible.

Slightly different subject, but the Royal Navy still has, as far as I am aware, conventional subs, which run on huge LA batteries while underwater. Some of these batteries, which are very well serviced and looked after by experts, are over 50 years old and may have seen service in several subs......

The same goes for telephone exchange emergency batteries, very large and last a great many years.....

May I ask you exactly what are all these people, apparently doing the right thing, that your experiences are apparently the opposite?

Look here, all these desciptions show the opposite to what you are saying, why is that?

https://nortonsafe.search.ask.com/web?o=APN12178&l=dir&qo=serpSearchTopBox&doi=2021-01-14&cmpgn=nov20&p2=%5EEQ%5Enov20%5E&q=differences+between+leisure+and+normal+lead+acid+batteries%3F

Many thanks for your anticipated and accurate reply

Andy

Sad to say, but they must have been badly designed.

I have a leisure battery, bought in 2004, that I kept in my caravan, which I recently sold with the same battery, still working with little or no capacity loss.

The only possible difference was a charger that I designed and built, to perpetuate the battery for as long as possible.

Slightly different subject, but the Royal Navy still has, as far as I am aware, conventional subs, which run on huge LA batteries while underwater. Some of these batteries, which are very well serviced and looked after by experts, are over 50 years old and may have seen service in several subs......

The same goes for telephone exchange emergency batteries, very large and last a great many years.....

May I ask you exactly what are all these people, apparently doing the right thing, that your experiences are apparently the opposite?

Look here, all these desciptions show the opposite to what you are saying, why is that?

https://nortonsafe.search.ask.com/web?o=APN12178&l=dir&qo=serpSearchTopBox&doi=2021-01-14&cmpgn=nov20&p2=%5EEQ%5Enov20%5E&q=differences+between+leisure+and+normal+lead+acid+batteries%3F

Many thanks for your anticipated and accurate reply

Andy

It comes down to how they are used. Run flat frequently = short life. Short life = disappointment.

It comes down to how they are used. Run flat frequently = short life. Short life = disappointment.

Any LA Battery, totally misused, will dissappoint the idiot that ran them like that.

The plus point on a Leisure battery, also often called a deep discharge battery for obvious reasons, is that if it is recharged reasonably quickly, it will live to charge another day. Say within 24 hours, no damage caused.

True car batteries are often wrecked completely if they are run down to nothing! JUST ONE TIME WILL DO IT!

Plus having some (relatively!) simple electronics to monitor the battery voltage and to cut off discharge at some preselected point, will of course prevent serious damage tp either type.

Read some of the documents I posted, you could learn a lot, if you so wished!

Have a nice day.

Andy

I agree - it comes down to usage.

As an ex BT maintenance engineer I know that exchange batteries are floated, that is to say they are permanantly on charge.

They are mainly there as a smoothing device to take out/absorb transient spikes coming from the 50v power plant. They also provide a short period of exchange main load backup during mains failure, but this only lasts as long as it takes the generator to auto start and get to speed. So they are never deep cycled.

Given the far more reliable mains and electronic exchange equipment, I'm not even sure they still use this system.

I agree - it comes down to usage.

As an ex BT maintenance engineer I know that exchange batteries are floated, that is to say they are permanantly on charge.

 

They are mainly there as a smoothing device to take out/absorb transient spikes coming from the 50v power plant. They also provide a short period of exchange main load backup during mains failure, but this only lasts as long as it takes the generator to auto start and get to speed. So they are never deep cycled.

Given the far more reliable mains and electronic exchange equipment, I'm not even sure they still use this system.

What you said was fully correct, but some of the terms you used may not be fully understood by other members here.

For example, floating a (for example only a 12v nominal battery), sets a max voltage, so that the battery only charges up to a specified voltage level, usually well under what some term FULL = over 14 volts. Cars often charge up to around 14.5 volts. Causing the battery to gas.

This way the floating battery never gases, which is a further danger to life and limb as it not only dispels the water in the acid, but delivers a gas mixture of oxygen and hydrogen, very explosive, as many have found to their cost!

Floating, if done correctly, extends the life of LA batteries tremendously!

My style of "Floating".....

I used to set my caravan charger max voltage at 70% of the rated battery capacity, for say a 12 volt nominal battery, that would be somewhere around 13.2 volts. Different manufacturers specify different levels.

Also, I cut the load at around 11.6 volts, below which damage (starts) occurs to a normal LA battery, particularly if left below that for long periods, as I treated my leisure battery as a normal 12 volt, even though it was deemed safe to drop well below this......I sincerely believe that is why that battery lived so long (is still living!).

So under both the floating charge and any 12 volt loads, the battery would sit somewhere betweel 11.6 and say around 13.3 volts.....

Remember this was for a caravan, and it was charged either from the car alternator when underway, via the charger circuit, mains when parked, except when parked at a camping site with no mains (the best ones!), when I would either start a portable generator, or run the car engine for 10 minutes or so, every 3rd day or so.

I changed all the lighting to either LED type bulbs, or 12 volt tubes. Good light and low power drain. My SAT receiver/TV took the most power, but it was still acceptable.

The car I used for towing had a 120 amp alternator, and a second 12v battery for the Diesel heating system under the front passenger seat, so I had a lot of 12 volts available one way and another!

Memories!!!

regards

Andy

Any LA Battery, totally misused, will dissappoint the idiot that ran them like that.

The plus point on a Leisure battery, also often called a deep discharge battery for obvious reasons, is that if it is recharged reasonably quickly, it will live to charge another day. Say within 24 hours, no damage caused.

True car batteries are often wrecked completely if they are run down to nothing! JUST ONE TIME WILL DO IT!

Plus having some (relatively!) simple electronics to monitor the battery voltage and to cut off discharge at some preselected point, will of course prevent serious damage tp either type.

Read some of the documents I posted, you could learn a lot, if you so wished!

Have a nice day.

Andy

Many of those people are not idiots, they have simply relied too much on others and claims on labels.

Have you ever considered being a little less harsh in your posts? One thing I really like about this forum is its overwhelming helpfulness and lower than normal level of negative qualities. May I venture to suggest you could increase the sum of human happiness with some thoughtful pre-post reviewing?

Numbers:

 

Your 48V 20Ah bike battery is around 960Wh, taking the label literally. The charge efficiency of lithium ion is close to 100%, so you need 960Wh plus a bit to allow for the charge controller efficiency from your solar for a full charge from flat. Call it a round 1000Wh, because you don't really want to run it completely flat.

 

If you need that every day, then you will need about 200W of solar panels: an average day between April and September will give you 4 or 5 Wh for each W of solar panel. A pure blue sky will give more than 10, I.e. 2000Wh from 200W panels, enough to charge two such batteries.

 

So your 150W panel, if in good working order, is reasonably close to that, so I would start with that and a cheap Elejoy controller for direct charging.

 

Indirect charging via a lead acid leisure battery, or better, a LiFePO4 lithium battery, needs more panel and a fairly large intermediate battery. I took two 40Ah, 4 cell so 12.8V nominal LiFePO4 buffer batteries with me on my Scotland to Wales ride last October, leaving home with them fully charged. 40Ah x 12.8V is 512Wh each.

 

I found that using a Sterling Power 150W quasi sine wave inverter and the standard Shimano 1.8A charger, each put only 80% into a flat 418Wh Shimano E8014 battery - just 330Wh or so - before the inverter reached its 10.5V low voltage cutout. That's only 65% combined efficiency from inverter and charger, which roughly equates to 80% efficiency each, which is plausible.

 

So to go that route, you would need 1.5 times as much solar panel for a start, and then enough buffer battery capacity to match the 1000Wh needed by the bike battery. At 12V, 1000Wh is just over 80Ah, so allowing for inverter and chargef efficiency, 120Ah of usable capacity is required.

 

As a general rule, going below 50% depth of discharge is not good for the life expectancy of lead acid leisure batteries, so assuming you always have a full leisure battery to begin charging, it needs to be at least 240Ah. However, in the real world, it will not always be full, so either it needs to be yet larger still, or a separate 'low voltage cutoff' device will be needed to protect it from deep discharge. The inverter will keep on going down to a horribly low cutoff, which will trash the leisure battery in a matter of months.

 

It is also necessary to allow for the poor round trip efficiency of lead acid batteries: you only get back about 70% of the energy used to charge, which translates to needing even larger solar panels. To get the same effect as the direct charging using your existing 150W panel, you would need to increase by 50% for the inverter and charger efficiency losses to 225W, and then by about 50% again to 340W for the round trip losses.

 

Summary:

 

Direct charging will do fairly well with your existing 150W panel, and needs only a charge controller and wiring to set up.

 

Indirect charging needs double or more solar panel, about 240Ah of leisure battery, low voltage cutoff device and suitable inverter.

 

If you can find another 48V battery that fits the same mount as the first, I think the two batteries, direct charging setup is probably the way to go.

Thanks thats a helpful summary. I do have two 120ah leisure batteries kicking around so I might try that route first, just as its cheap for me. I have been looking at putting LION cells together. My cousin has actually put together a 3.6kw battery doing this in his garage! Only weighs about 25kg apparently. Overkill for me, but it was interesting! If the leisure batteries don't cut it though, I think I will do as you suggest and get another 48v battery for direct charging.

Many of those people are not idiots, they have simply relied too much on others and claims on labels.

 

Have you ever considered being a little less harsh in your posts? One thing I really like about this forum is its overwhelming helpfulness and lower than normal level of negative qualities. May I venture to suggest you could increase the sum of human happiness with some thoughtful pre-post reviewing?

HARSH! No swear words, no picking on anyone in particular, just general terms.....If you feel picked on, you read that into it all on your own.

You should read some of the replies I get from people who could not find their pwn backside if given an hour or so to do it!

Some Pedelecers are more of a study for other people wanting to learn more, first hand, about the "Dunning Kruger Effect".

I wish you again, a great day.

Andy