How to charge a 60V/45Ah lithium-ion battery from a 12v DC motorhome?

[BarcombeBoy]

Hello.

I take an electric motorcycle with me. My vehicle doesn't have AC (and I don't want it) so currently I have to stop at a campsite to charge my bike. This costs me over £30 for the hookup. At home charging the bike costs me £1.20. :-(

Currently I have a 140amp alternator, a 330W solar panel with Victron controller, a 130ah lead acid battery and a split charger. I am probably going to upgrade to a 250AH lithium battery with BtoB charger in the not too distant future. When I do I'd like to ensure I can charge my bike's battery, even if it is slowly. The bike's battery is 60V/45Ah lithium-ion power pack (2,700 watt-hours).

It seems silly to convert to AC and back so I'm assuming I need some sort of DC to DC convertor to go from 12v to 60v?

Does anyone know what I should do? It might be an issue that someone with a mobility scooter has already solved.

Thanks for any input.

 

[Tombola]

Only 2ah but seems to convert

https://www.amazon.co.uk/converter-supply-voltage-increase-transform/dp/B0D5VC2CF2?tag=mhf04-21

 

[Jev88]

Sounds simpler to have an inverter and just plug your normal bike charger in.
If the battery is removable to charge you can have it on whilst driving and the leisure battery won't work too hard as the B2B will be pumping energy into it.

 

[JockandRita]

Sounds simpler to have an inverter and just plug your normal bike charger in.
If the battery is removable to charge you can have it on whilst driving and the leisure battery won't work too hard as the B2B will be pumping energy into it.

BarcombeBoy. My thoughts on the solution too. I have charged 2 x E Bike batteries at the same time off an inverter, but I grant you, not at 45A.

Cheers,

Jock.

 

[MisterB]

Hello.

I take an electric motorcycle with me. My vehicle doesn't have AC (and I don't want it) so currently I have to stop at a campsite to charge my bike. This costs me over £30 for the hookup. At home charging the bike costs me £1.20. :-(

Currently I have a 140amp alternator, a 330W solar panel with Victron controller, a 130ah lead acid battery and a split charger. I am probably going to upgrade to a 250AH lithium battery with BtoB charger in the not too distant future. When I do I'd like to ensure I can charge my bike's battery, even if it is slowly. The bike's battery is 60V/45Ah lithium-ion power pack (2,700 watt-hours).

It seems silly to convert to AC and back so I'm assuming I need some sort of DC to DC convertor to go from 12v to 60v?

Does anyone know what I should do? It might be an issue that someone with a mobility scooter has already solved.

Thanks for any input.

Raul
autorouter

might have a suggestion

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[Raul]

Can you post the data for your bike battery? Is it nominal 60v what's the cell count?
A victron 12-48 DC to DC converter can go up to 58v

 

[oldiesontour]

The cheapest,simplist most straightforward solution is a 12v to 240v psw inverter...as a bonus can be used for other purposes as well

 

[Lenny HB]

Best option is to use a decent quality inverter like Victron and use the bikes mains charger, nice and safe no chance of damaging the battery.

 

[BarcombeBoy]

Thanks for the comments. I will go the inverter route if I have to but converting to AC just to have the charger convert it back to DC seems silly and won't be very efficient. And I really don't have any other need for AC.

As for the battery. It does remove from the bike (and in fact is only in it when I ride the bike) so I expect it to be charging as I drive and from solar when I'm parked up..

Battery specs:
60V/45Ah lithium-ion power pack (2,700 watt-hours).
LG 50LTs. 3.63v 16S (therefore in actuality it's a 58.8v battery)

 

[autorouter]

Battery specs:
60V/45Ah lithium-ion power pack (2,700 watt-hours).
LG 50LTs. 3.63v 16S (therefore in actuality it's a 58.8v battery)

If it's a 16-cell battery then it is in fact a nominal '48V' battery, similar to the type of battery found in a house battery storage unit. Be very careful charging with a charger other than one that the manufacturers allow. It probably won't be Lithium Iron Phosphate (LiFePO4), which is inherently much safer. It probably will be one of the other technologies (Lithium-Cobalt, Lithium Polymer etc) which can cause an almost inextinguishable fire if damaged, with very toxic smoke to add to the problems. Use the charger that came with the battery, and just get an inverter.

I would think a 1000W inverter is likely to be OK for that battery (2700Wh in 3 hours requires 900W). But you would need to read the label on the charger, to see what wattage is required.

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[Raul]

If it's a 16-cell battery then it is in fact a nominal '48V' battery,

No it's a diferent animal li ion LG nominal 3.7v and charges to 4.1-4.2v like NMC
The 16 you mention is 3.2v nominal, these are much higher. For lfp equivalent this ones would be 14S like nissan leaf modules.

 

[Raul]

Battery specs:
60V/45Ah lithium-ion power pack (2,700 watt-hours).
LG 50LTs. 3.63v 16S (therefore in actuality it's a 58.8v battery)

In the light of that info, I would strongly recommend to use the existing charger, and a inverter just big enough to cover the charger output. Your battery is a true 60v and even if you come across of an adjustable output dc converter, it will still be a single voltage output, and will need manual intervention to unplug before terminate the charge.
The cells are a bit more volatile that the Lifepo4, and will not tolerate any abuse, stick to the charger provided. Those are high C rate traction cells, don't risk it.
Your battery fully charged will be 65-66v at least or even 67v

 

[BarcombeBoy]

Hi Raul.

Yes, battery fires are a worry but I'd assumed that a DC slow charge converted from a DC source would be pretty safe (maybe erroneously) as dirty AC seems to be a bit of an issue with chargers and batteries.

It's a Lithium-ion battery. I've attached a photo of the charger label.

I will use an inverter if that's the best route but I had assumed that the charger would pull far too much power and that a slower DC charge would be more compatible with a standard motorhome electrical setup. I'd welcome your thoughts on this.

If my setup would be capable of providing enough power to an inverter to run the charger correctly can you suggest what size it should be?

Thanks.

 

[Raul]

Nickel cadmium or cobalt manganese 3.7v nominal, fully charged 4.2v, same as nissan leaf cells, but better quality of LG

I was right in terms of voltage, 67.2v X 12A = 806.4W, round it up to 1000W via inverter.
It is doable of a 300Ah or more lithium battery, and any decent 1KW inverter. I recommend a victron inverter.

The reason I said to stick to the charger, I think it may have comms built in to communicate with the pack and trim accordingly as the cells fill up, or balance.

I'm very interested in the bike, can you tell us more please? Power, weight, brakes, shocks tyres etc. Thank you.

 

[Markman]

Another alternative might be the Campervan Electrics forum on the Facepage site. Very techie, friendly, knowledgeable people there.

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[jumar]

Another alternative might be the Campervan Electrics forum on the Facepage site. Very techie, friendly, knowledgeable people there.

Which we are blessed with here on Fun...we have some very competent knowledgeable Members on here, the very ones that have contributed to this and many threads in the past.

 

[mikash]

That's a pretty big battery and charger compared to the van electronics. The battery is essentially the same size as your planned lithium battery (3000Wh vs 2700Wh) and the charger will pull amps comparable to running an AC unit.
I'm curious if you've done some estimation of how often/much you typically need to charge? Just so you don't end up in a situtation where you install all the goodies and realize it's just not enough for what you had in mind.
Your 140A alternator can probably comfortably push out some 500-600W with a B2B so assuming 80% efficiency after all the conversions, one hour of driving would charge maybe about 15% range back to your bike.
Solar is a bit more complicated to estimate since the output varies so much based on season, weather and time of the day but I think on a good day you might get 50% range charging all day. Just don't go biking around the noon when the solar yield is best
Since you'll be using your leisure battery as a buffer (even in the best case of charging wile driving on a sunny day, few hundred watts will be pulled from the leisure battery to feed the inverter running the charger, but usually it'll be he battery doing most of the heavy lifting) it might be worth it to invest in a bigger than 250Ah battery pack. It'd give you some more wiggle room, allow you to arrive somewhere with more range in the bank and make fixed price EHU-visits more cost efficient when you can't avoid them.

You're getting good advice on the inveter already, but I'd like to add that since you have no other use for an inverter and sizing the inverter to be just enough is probably best as already suggested, it is worth noting that many inverters are less efficient at close to full load. Now, the difference between f.ex., 92% and 85% efficiency is not going to ruin your energy budget, but it does mean that the device will be generating double the heat. And since you'll be running that inveter at close to full load for hours at a time and not just 2 minutes for microwave here and 2 minutes for ketttle there, it'll be important to ensure the installation is done so that the unit can shed heat properly. Otherwise you might find out that on hotter days it'll start downrating or cutting out due to overheating, and your chargerr won't work.

 

[BarcombeBoy]

I'm very interested in the bike, can you tell us more please? Power, weight, brakes, shocks tyres etc. Thank you.

Thanks again Raul. That's all excellent thanks nfo and just what I required

The bike is a Talaria Sting R (aka MX4). It is a dirt bike. Mine is one of the rarer road legal versions. It is light and extremely nippy.. it has mountain bike brakes, 55mph top speed and two modes, Eco and Sports. Battery only lasts for around 25-30m if going full speed but I rarely do that. Use Eco mode (less acceleration and top speed governed to 30mph) and it goes on and on. Acceleration in Sports Mode is immense and a lot of fun. It's quite easy to wheelie the bike by accident.

I mainly avoid A roads and use it for country lanes and off-road. It came with knobbly tyres but I changed them for hybrid tyres. The opportunities for customisation are immense. Everything can be changed, upgraded, restyled.

I stick it on a towbar rack on the back of the van. A simple lift once the battery is out.

The Duracell stickers I put on the battery are a joke.

 

[BarcombeBoy]

Thanks very much for your informative reply mikash. I'd like to install a 350ah lithium battery but I just don't have a large enough free space.

My usage is likely to be this:

I wild camp in the most isolated places I can find mostly and use the bike for playing/exploring cross country or to visit local villages/towns for supplies. I can relocate every day or sometimes stay in one place for as long as 5 days (if I do the sun is likely to be out!). I remove the battery from the bike when not in use and stick it in the vehicle (a vague anti-theft measure).

I tend not to let the battery fully discharge, preferring to charge it up when it gets towards 50%. At home recharging it from this state will take around an hour.

So, it's reasonably likely that the battery will on charge most of the time I am not using the bike. Hence, my lack of worry about having a slower (DC to DC) charge time.

Judging by what you and Raul say and my usage/charging pattern am I right to think I may get away with a 250ah battery and a 1kw Victron invertor but it would be better to try to fit a 300 or 350ah battery if I possibly can?

Again, thanks. The help on this forum is proving invaluable.

 

[Raul]

I would get two 300Ah batteries, even if you don't have space for two, you can fit the second one away from each other. I have 400Ah on the wheel arch, and another 300Ah behind passenger seat under the sofa. Nothing stops you to link them together.
With 250Ah it's going to be a struggle and frustration, lithium is fairly cheap now, even cheaper if you build yourself. A 300Ah cell is £70 now compared to £150 5 years ago.
You want double the capacity of your bike, that way will leave you with plenty for off grid as well as charging the bike. The sun does not always shines, you need a buffer, or you will re visit this later again.

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[mikash]

Judging by what you and Raul say and my usage/charging pattern am I right to think I may get away with a 250ah battery and a 1kw Victron invertor but it would be better to try to fit a 300 or 350ah battery if I possibly can?

I think you might get by with the 250ah to some extent and the usage you described didn't sound that bad compared to the available charging, but I suspect you will bump into that capacity limit way more often than you care for in the long run. You will, after all, use the battery to power other van electrics too and since your focus seems to be off-grid, it will be a lot more enjoyable if you don't have to be counting amp hours all the time. And, like said, there will be the rainy days and cloudy days, and the whole of winter, when you're not getting much or any from the sky so that battery is really all you have before you need to go driving around or find an EHU.

Anything, really, you can get on top of that 250Ah would help significantly. I was about to suggest 2 x 200Ah as a starting point, but seems Raul upped the ante a bit alreeady . If you have some pro shop doing the installation, I'm sure they will have some ideas on how to make the install work with a bigger battery or two and even if you won't do it just yet, they might ibe able to take the possible future upgrade into account and install the first bits so that it's easier and cheaper to add another battery later without moving everything around.

Another thing that might help would be a second MPPT controller and a 200W-300W foldable panel to agument the 330W on the roof. I know those divide opinions a bit, but in your case I think it might be a good fit. They are easier to get close to the rated power out of compared to the roof panels since you can direct them so setting one up before you charge would reduce the battery drain significantly and since you plan to do a lot of wild camping in remote places there are probably many opportunities to use one without having to worry about space, vandalism or theft.

As for the inverter, the Victron 1200VA ones are rated for 1kw continuous power at 25c and a little less at 40c so one of those would probably fit like a shoe as long as it's got room to breathe and keeps cool.

 

[meanders]

The DC-DC up convertors basically use the same oscillator technology as an invertor. On the up cycle it charges an inductor (a coil to you and I) and the down cycle effectively switches it off and the 'charge' gets discharged at a higher voltage, so the DC output is pulsed on and off rather than continuous. In very rough terms, the speed of the oscillator determines the output voltage, but as voltage increases, current decreases. It it already much less efficient than an inverter as it's only outputting half the cycle, whereas an invertor outputs the full cycle. I also concur that not using the correct charger is foolish.

I also suggest that you do not buy a cheap invertor and make sure it is pure sign wave. The cheaper ones output much nearer a square wave that most switched-mode power supplies really do not like.

 

[autorouter]

If as you say you have no requirement for mains 230V, and wouldn't otherwise be thinking of a mains voltage inverter, there are a couple of other options.

A 'Power Station' is a combination of big lithium battery, an inverter, and two or three methods of charging the battery. You need one with at least a 1000W inverter, plus a battery capacity of more than 2700Wh. So a smaller power pack with a 1000W inverter, plus an extra battery expansion pack (or two) should manage that. You don't need to go for a very big single power station, because it will have an excessively big inverter(2500W to 3000W) as well as the necessary 2700Wh minimum battery size.

The advantage is it comes in one compact unit, and can be used in other situations apart from the motorhome.

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Another possibility is to get a special cable or adaptor to plug the motorhome into an EV charging point. Most chargers have a 'Type 2' plug, which can output standard 230V mains just like in your house. They would take two or three hours to charge an EV, which is why they are not as popular as the super-high-speed chargers.

You could plug the motorhome into the EV charger, then plug the charger into one of the motorhome sockets. You pay about 40p to 80p per kWh. Better than an expensive night on a campsite that you don't need.

In spite of the headlines showing banks of super high power 150kW chargers, by far the most numerous type of charger is a small 22kW Type 2 charger. They are available in many car parks and near hotels and garages.