Inverter size to charge ebike, help pls...

[SteveandSueJ]

I have a little knowledge but can someone help sanitise this pls. I am struggling to work out inverter size needed for occasional use maiy charging ebike with no EHU. My carrera crossfire ebike label on charger inputs 240v 2amp max, says it outputs 3 amps at 42v.

Battery says 36v, 11.6ah, 417wh.

I don't have solar yet but will very soon. I have 2 x 100amp leisure lead batteries in good condition (plus veh battery 100amp and have battery master fitted). Batteries charge fine from sargent ec450, 20 amp I believe (fridge off) when driving.

I am thinking 500w pure sine wave direct to leisure batteries and short cables.

Ebike only really used about 50% before recharge, usually but relevant for this example.

We generally prefer EHU but for some rally's, no EHU is the position.

At 50% enike battery use, how long would it take inverter to recharge? Will my setup handle this at present (I understand I will need to drive it until solar installed) and thinking around 120w solar as space limited with my 6m autotrail 2011 motorhome.

Am I totally off track here or is this doable?

Much appreciate some help so I can understand this better.. the ebike requirement has confused me... thx in advance...

 

[LesW]

I charge ebike batteries without an inverter..

There's lots of info on other threads if you do a search.

 

[Lenny HB]

The max power the charger will use is 480 Watts but you need a bit of overhead as you don't want to be running a inverter flat out I would go for 700 watt pure sine wave inverter.
Time to charge will be the same as when charging on mains.

 

[SteveandSueJ]

I charge ebike batteries without an inverter..

There's lots of info on other threads if you do a search.

What charger do you use? I assume a 12v? I have looked and can see some on amazon for bosch 3 pin but mine is 5 pin, halfords special unfortunately.

 

[SteveandSueJ]

The max power the charger will use is 480 Watts but you need a bit of overhead as you don't want to be running a inverter flat out I would go for 700 watt pure sine wave inverter.
Time to charge will be the same as when charging on mains.

Thx Lenny. Am I right in thinking at 480 watts per hour, around 40 amps per hour from my effectively usable 100 (50% of 2x100)... if not charging from driving or solar??

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[LesW]

What charger do you use? I assume a 12v? I have looked and can see some on amazon for bosch 3 pin but mine is 5 pin, halfords special unfortunately.

Have a read here, some helpful suggestions..

Charging ebikes when off grid.

We will be doing some off grid camping next month around Spain and I am looking at options to recharge our electric bikes Li-ion batteries (245wh 36V 6.8Ah). I dont think my solar , battery & invertor (300w) would be up to the job, but found 12v chargers which can be run from a cig socket...

www.motorhomefun.co.uk

Plus a link to a charger.

 

[SteveandSueJ]

Have a read here, some helpful suggestions..

Charging ebikes when off grid.

We will be doing some off grid camping next month around Spain and I am looking at options to recharge our electric bikes Li-ion batteries (245wh 36V 6.8Ah). I dont think my solar , battery & invertor (300w) would be up to the job, but found 12v chargers which can be run from a cig socket...

www.motorhomefun.co.uk

Plus a link to a charger.

Ahh. Thx LesW. I had identified and contacted powatechnic already and they do not do the plug size I have for halfords carrera ebike. Worth a try and I appreciate your reply... back to an Inverter methinks.

 

[autorouter]

If you look at the mains charger output, it says 3A at 42V. That's a power of 126W. Allowing for conversion losses I would think that the input of the charger is about 150W. The figure of 240V 2A = 480W is probably the maximum inrush current when the charger is first plugged in, and it will quickly settle down to about 150W. So I think a 500W inverter is worth a try, especially if you can find some way to try it before you buy.

The battery is 417Wh, so that's equivalent to 417/12 = 35 amp-hours at 12V from your 200Ah of battery. I think 120W of solar panel will produce at least 35Ah on an average summer day, and maybe up to 50Ah on a good long sunny day.

 

[SteveandSueJ]

Can you clarify how I connect the inverter pls. I have my 2 x 100a lead batteries in parallel. The Inverter is 1000w version even though I won't use all that, but I have bought new 100a cables, fuse, isolator switch rather than use the 70a cables supplied. Should I connect live to battery 1 and neutral to battery 2 as balance? I ask as the current link cables are smaller than the 100a ones... should the link cables also be 100a? Thx in advance...

 

[autorouter]

Should I connect live to battery 1 and neutral to battery 2 as balance? I ask as the current link cables are smaller than the 100a ones... should the link cables also be 100a?

Yes that's a good way to connect to two batteries. In theory the links can be a bit thinner than the main cables, they take about half the amps if the two batteries are equal. But it's usual to use the same thickness of cable because it's usually easier - only one size of cable needed.

Cable is usually specified by the cross-sectional area (CSA) of the copper conductor in millimetres squared, because the best cable for the required amps can vary depending on your requirements. Obviously you don't want the cable to overheat, but also you want to be sure the voltage drop along the cable is acceptable. The longer the cable, the thicker it has to be to keep the voltage drop acceptable. If the cable is sized so that the voltage drop is less than 3%, then that also ensures that there is no overheating.

The CSA of the cable is usually embossed on the cable sheath - shine a torch at a shallow angle to show up the numbers better. What size are your cables?

There are several cable size calculators online, such as this one. Enter the length, CSA and system voltage (ie 12V) and it tells you the voltage drop, and what percentage.

Voltage Drop Calculator | 12 Volt Planet

Use our Voltage Drop Calculator to select the correct Cable for your campervan, motorhome or boat wiring application. Auto and Marine Electrical Components from 12 Volt Planet - Cable Size Calculator

www.12voltplanet.co.uk

For a 12V system, with a 100A current, 1 metre flow and return, using 10 square millimetres cable, it says 3.03%, just about OK.

By the way, battery connections are DC, and are called positive and negative. Mains connections are AC, and are called live and neutral.

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[SteveandSueJ]

Fab answer. Thank you Autorouter. Supplied cables are 10mm2 so around 70 amps. I await 16mm2 to be safe and will use those with fuse, short runs as positioned within a foot of batteries. Manual says run red and black cable to both + and - terminals of both batteries, connecting to + of 1 and - of other battery. My current link cables are much smaller than 10mm sq I guess as van was not handling such high amps in original state. But as u suggest, I will run new link cables. Again, many thanks for sanity checking what I am doing... I am learning. .!!

 

[autorouter]

The aim is to ensure the voltage drops along the cables to each battery are equal, so one battery doesn't get to do more work than the other, and maybe wear out earlier than the other one. Your first method, of positive to one battery, negative to the other, works fine for two batteries, but not so good for more than two. The method in the manual also works, for any number of batteries, but uses a lot of cable, and doesn't allow for a fuse or isolator.

Another possibility is a single positive from the inverter to the fuse/isolator, then equal length links from the fuse to both batteries. On the negative side, a single negative from the inverter to a busbar/common negative point, then equal length links to both batteries. If the distance is short, it may be just as easy to use two cables for the negative, as the manual says.

 

[VXman]

If you are worried about the amount of power the charging will takeout of your batteries then try spreading the charging over a couple of days - or even while on the move.

I have an electric motorbike (moped/scooter type thing) so it has a BIG battery. I have charged it from my 3 110ah batteries but in stages. A few hours one morning - then let the solar replenish the batteries and then a bit more the next day. I don't need the battery to be full to use it for shorter journeys.

I have also charged it (in the garage) on the move. Ran an extension cable from the in the lounger inverter to the garage. Charged without much being taken from the battery over 3-4 hours of driving. Hoping it will be even better when I fit my extra solar (350 watts in total)

 

[SteveandSueJ]

Thx Autorouter and VXman....

Parts arriving and will start the work now I feel confident following all your advice. Upgrades like this are not Rocket Science but when first time fitting to a new (to us) Moho, confidence is needed and that is what you have provided. Thank you.