Inverters and charging your eMTB

[TimR123]

Hi...
Im not conversant with the details of making this set up work but if I might ask...

My T5 is equipped with a split charger, and two leisure batteries ( 2 x 350Wh (80aH) ) and two solar panels on the roof topping up the charge.
I also have an 800W inverter fitted ( 800W continuous and 16ooW peak output 12v- )
I wanted to charge my Shimano battery with the supplied charger using the UK standard 3 pin plug...I understand the Shimano uses 450w...thought this would be within limits...


Plugged it in, and without even loading the charger by connecting it to the bike's battery pack...the inverter went up in a puff of smoke !!

Have I missed something..?
Is there something about the inverter that isnt upto spec..Not sure if its pure sine or modified. Would it make the difference ?
I wasnt running the engine at the time. ( So not using alternator to supply current but with solar panels and 2x 350wH batteries...it should have at least managed stand by??)

Clearly, I need to do some investigation but.....

Should i persevere with an upspecc'ed pure sine wave inverter ( I had planned on using tyre warmers from this set up but havent tried it yet) This was the first time Ive used the inverter, that incidentally, seems to get over warm when left on , unloaded, for any period of time, bleeping ...Its a Streetwise 800W (https://www.amazon.co.uk/Streetwize-SWINV800-Peak-Inverter-1600/dp/B000YKYF9I)

Thought Id be ok but alas no- fried it !
Any help appreciated..

Tim

 

[Deleted member 25121]

What's the input current rating of the charger?

 

[TimR123]

Input 100-240v ~ 2.5A 50/60Hz

 

[Deleted member 25121]

The charger shouldn't place any harsh demands on the inverter unless it's faulty.

I'd put the problem down to a poor quality inverter. A medium quality sine wave inverter with a 800W rating or more should be OK.

 

[Steve100]

You need a pure sine wave inverter for anything electronic.
A modified sine wave inverter has a square shape power output which is fine for powering motors or heaters but any delicate electronics will immediately go up in smoke !

 

[Benjahmin]

I agree about a sine wave inverter, the smoother the better.
However, this has been discussed many times and I'm not sure it stacks up. Your leisure batteries are nominal 700Wh, how much of that is usefully available is moot. Your bike battery, full charge, is 450Wh. Allowing for inefficiency losses in both the inverter and the bike charger i think you'd risk deep cycling your leisure batteries, despite the solar.
Partial bike charge from full leisure would work, but with fridge, lighting etc., I think you'd be looking at running the engine after.
Let us know how you get on as it's something I've looked at and not been convinced I can make it work. I am looking at charging two bikes though and that's a biggy.

 

[smifee]

Disclaimer:- I am a total mechanical, electrical and DIY numpty.

Motorhomed with batteries ( 4 x 125Ah ), 2 x 75W solar panels, inverter ( 3KW peak 1.75KW constant ) and Sterling B2B charger for 10 years.

Firm fitting all the above said a pure sine wasn't necessary. They said would replace the inverter and anything it damaged at their cost.

I ran toaster, TV, Sky box, bread maker, washing machine, spin dryer, battery charger for AA & AAA batteries & electric toothbrush charger off the inverter without any problems.

I knew I couldn't use a microwave oven because of it's high startup draw. I was surprised to find my bean to cup coffee machine & coffe pod machine wouldn't work from the inverter despite being well within the inverter limits. Assumed they had high startup draw.

 

[Deleted member 25121]

I was surprised to find my bean to cup coffee machine & coffe pod machine wouldn't work from the inverter despite being well within the inverter limits. Assumed they had high startup draw.

Or possibly a problem with their power supplies caused by the irregular waveform.

 

[TimR123]

Look..Im not a running a fridge or hairdryers or any of that creature comfort gubbins...!
Alls I wanna do it charge the bike battery...and this could be done in part anyway, with the engine running as there is a split charger on the vehicle... ( see OP)
I think I know of others who successfully manage this with simialr set ups..( its the internet. Yiou cant believe everything you read...so thats my disclaimer!)
The issue is this- the inverter went
up in a puff of smoke within seconds of connecting the charger ( without load- see op)

 

[Benjahmin]

OK, I'm guessing here.
First thought is condensation, not sure what the weather was at the time.
Second thought, are there inrush capacitors in the charger? I know there are in the battery bms.
Third thought is - coincidence, I know! But perhaps it was just time, don't know how old it was.

 

[TimR123]

This explains the way my two leisure batteries and solar are set up..

Main article: Solar inverter

A solar inverter is a balance of system (BOS) component of a photovoltaic system and can be used for both grid-connected and off-grid systems. Solar inverters have special functions adapted for use with photovoltaic arrays, including maximum power point tracking and anti-islanding protection. Solar micro-inverters differ from conventional inverters, as an individual micro-inverter is attached to each solar panel. This can improve the overall efficiency of the system. The output from several micro-inverters is then combined and often fed to the electrical grid.
In other applications, a conventional inverter can be combined with a battery bank maintained by a solar charge controller. This combination of components is often referred to as a solar generator.[13]
Main article: Solar inverter


Pure sine wave is manufacturers speak for modified sine wave...one step, two step or three step is the choice available commercially- so called "pure sine wave" is three step...It basically pauses between alternating in effect , by overlapping @ 90 degrees to 'simulate' a sine wave ( if you squint very hard and forget your glasses) Not necessarily an issue.
Im thinking the charger is a transformer..right ?
Inductive loads ?
Other uses...?

Im guessing nobody has actually tried it , so maybe this is the wrong audience...?

 

[Deleted member 25121]

Here's a tip - if you're looking for assistance on a forum then you might find that people are willing to spend time trying to help if you don't get angry at them.

 

[TimR123]

Im not angry mate...
I was after some informed advice....
Talk amongst yourselves by all means...!

 

[Deleted member 25121]

See what I mean, sarcastic as well....

 

[Ocsid]

I had checked (2016) and was told then not to use a modified sine wave inverter on my Impulse charger. The inference though, was it screwing up the expensive charger.
At the budget price of that 800Watt inverter, IMO it will be a long way off being a refined pure sine wave unit.

 

[TimR123]

Pretty sure it wasnt a so called 'pure sine wave' inverter, no.
Doesnt explain why it smoked the inverter though and not the charger..? Why I was after some erudite insight, or whatever...!
BTW- from what I have learned, commercially available units are typically 1, 2 or 3 step inverters..3 step inverters being what the manufacturers are calling 'pure sine wave'....They are all modified, it a question of how much...They overlap the wave format by 90 degrees to emulate the sine wave ( if you squint) It essentially creates a pause between switching. ( WIKI, what do they know?)
I pulled down some stats from the charger...It seems to run @ 180 watts on 0.8 amps whilst charging. So pretty modest...
I think capacity shouldnt be the issue..?
Delicate electronics may well be the concern going forward...

Im surprised more eBikers havent looked ast this TBH.
Off grid is the future..

 

[Ocsid]

Whilst the charger you said drew 180 Watts when connected to the battery, here in blowing the inverter you did not get as far as exposing the inverter to that, from what you said. Yes?

You did, however, expose the inverter to the charger's off load inrush starting current, that could easily peak much higher. Well, it will have start up spikes as the photos show inductive transformers.

What is printed on the charger for the AC current, any value quoted?
That value will be rated to cover the inductive load, a value the inverter has to achieve.
We camp a great deal off grid so faced the same challenge. After a little though I concluded the concept of recharging a worthwhile amount into a bikes battery, would take far too big a chunk out of the van's battery to ever be healthy. Just the same realisation "Benjahmin" made right at the start.
My pragmatic route is like this. Put your charger in the pannier and go for a lingering couple of hours at one of the coffee shops, getting a decent boost, or lunch at a friendly pub that allows you a top up; all done a full charge is only 10p worth of mains power.
Otherwise, you have to be thinking IMO of a bigger, cleaner inverter, for use only whilst driving your vehicle where the alternator will readily cope.
Using your batteries alone will soon wreck them by the depth of discharge needed.

 

[cyclebuddy]

My T5 is equipped with a split charger, and two leisure batteries ( 2 x 350Wh (80aH) ) and two solar panels on the roof topping up the charge.
I also have an 800W inverter fitted ( 800W continuous and 16ooW peak output 12v- )
I wanted to charge my Shimano battery with the supplied charger using the UK standard 3 pin plug...I understand the Shimano uses 450w...thought this would be within limits...

This doesn't read right: The Shimano battery capacity might be 450w (ie 12.5A @ 36v?), but a typical ebike charger only draws 80-100w @ 240v when charging. An 800w inverter should cope easily with that. I use a 400w inverter in my own T5 to charge ebike batteries (both "square wave/modified sine" and "pure sine" inverters work without issue).

The inverter you link is a bit rubbish though - especially given the spend on your solar etc. I think you've just been unlucky.

In practice you'll generally only get one and a bit full bike-battery charges from each full leisure battery. Neither Solar nor a T5 alternator (14A) will replenish that in a hurry: You'll need an overnight camp-site/mains hook-up/petrol generator to recharge your leisure batteries properly. That may be why most people end up not bothering?

 

[Ocsid]

"Neither Solar nor a T5 alternator (14A) will replenish that in a hurry: "

Are you sure the T5 ever got just 14A alternators?

I have not got a T5, but thought even their small 1.9 Tdi VW engine came with a minimum of a 90 A alternator. Plus there were options of higher rated versions.

Is it that the associated controls limited the amps to the battery to 14?

 

[cyclebuddy]

I have not got a T5, but thought even their small 1.9 Tdi VW engine came with a minimum of a 90 A alternator. Plus there were options of higher rated versions.

I'm not sure how VW rate alternators technically, but a typical T5 starter battery of 70-100Ah charging at 90A would gas very badly.

The 14 amps I measured with a Fluke Clamp charging a very depleted but healthy Bosch S5 100Ah in a 2006 VW T5 2.5L TDI. In practice, it really does take 100/14 = 7+ hours to fully recharge from empty (10.5v) - 10 hours with a 12A mains charger (CC/CV).

Your pragmatic pub/café e-bike charging solution seems a better option to me (even with two bike batteries and an inverter/charger just in case I'm really off-grid).