#140020  by Ramber1
 Mon Apr 30, 2018 11:10 am
We have a Roller Team 694 with a 120 watt solar panel, 10 amp Vechline controller and a Varta 95ah house battery. I am considering buying an e bike and ask what would best option be to upgrade system to run inverter to charge batteries. Looking at possibly replacing house battery with 2 larger ah and running a ? 600watt inverter. E bike battery is 13.8ah 36v, 500 watt.
 #140021  by gerard
 Mon Apr 30, 2018 12:17 pm
We have two ebikes (full size, 36 Ah/400 W batteries). We charge both using a Victron 1600 W inverter. You could get away with a smaller inverter, we use this to also power our Nespresso.
We charge the bikes together, from two Varta LA 95 batteries (I suspect the same as you have). Very happy with the batteries, they can handle large discharge currents (CCA 850A, SAE 1063A). Never had a problem with charging both bikes at the same time (or the Nespresso). However charging even one bike will take out at least 36 Ah out of the battery if charge from empty. Usually we do so while we are driving, but sometimes when parked up (300 W solar).

Gerard
 #140022  by Nut17
 Mon Apr 30, 2018 12:35 pm
Hi Ramber1. If you have room on your roof, I would first concentrate on fitting as much solar on your roof as possible. Our ebike chargers draw around 6 amps @ 12 volts and take about 2.5 hours to top up our batteries from around 50% discharge. This equates to around 15 Ah from your battery which would equate to a minimum of 3 - 4 hours full sun from your current solar panel. A 300 w pure sine wave inverter would easily cope with the demand, but a 600 watt one would be sensible as it would enable you to run other appliances that may require higher start current.

You will also need to factor in the reduced solar harvest achieved over the Autumn - Spring months and even more so in the South Island. Not to mention sustained overcast conditions, and this is when an increase in battery capacity will become a necessity.
 #140037  by Ramber1
 Mon Apr 30, 2018 10:14 pm
Thanks guys, plenty to think about

Cheers Rob
 #140057  by Ramber1
 Tue May 01, 2018 2:51 pm
Went to local battery and solar supplier to see about more solar and battery. He said that we would kill any lead acid batteries using an inverter to charge ebike batteries.
 #140067  by gerard
 Tue May 01, 2018 6:25 pm
I would look for another battery retailer, sounds like he only sells standard starter batteries? There are good lead -acid based AGM batteries on the market that are more suitable than your standard starter battery. With a suitable type battery, and enough Ah capacity there is no problem, especially when supported by solar. Been done for years by our European camper friends. Our batteries (two Varta LA95's AGM) are two years old and not showing any signs of deterioration, yet apart form charging the ebike batteries, we also use the Nespresso (1400W ) and sometimes a hairdryer through the inverter. We do have 300 W solar to support house battery charging, and try to use house batteries wisely. Making 4 cups of coffee and then recharging two ebike batteries would be hard on the house batteries and likely reduce its life.

Our Ebikes have a range of 120 km, with a 418 Wh battery (42V, 10Ah). At 75% discharge, it pulls 18A from the house battery for a short time, then drops to around 12 A and progressively lower after that. Even when charging without support from the car generator or solar panels, I haven't seen the battery voltage drop below 12.1- 12.2 V. I would guess that most ebike batteries have a lower capacity, I hear ranges of 40-60 km stated frequently, suggesting perhaps 200Wh batteries? But yours is at the higher end at 500 Wh.

Recharging our Ebike 400 Wh battery from around 70 % discharge will take about 30 Ah total over three hours. That is a bit more than desirable for most single 95 Ah batteries, the recommendation is for 20-25 Ah before charging the house battery again. Frequent discharge of the house battery in excess of 25 Ah will shorten its life (reduce the number of discharge cycles left).
Your E bike battery of 13.8ah 36v, 500 watt should be no problem if you have 2 suitable batteries around 200 Ah total. However you may need to recharge them (solar, or driving) in order to be able to use other appliances (lights/pumps/fridge/tv) without long term affecting battery life significantly.

The German RV "Reise Mobil" magazine (September 9, 2009) has doen a comparative test of 7 different 95Ah battery brands that are often used/recommended for campers. They used a test cycle of 45 mins discharge at 10A, 15 mins of 80 A (!), 1.5 hr of discharge at 20 A before recharging. Interesting reading.
 #140068  by Neddy
 Tue May 01, 2018 7:11 pm
Ramber1 wrote:
Tue May 01, 2018 2:51 pm
Local battery and solar supplier said that we would kill any lead acid batteries using an inverter to charge ebike batteries.
Twaddle. With even a relatively modest 300 watts or so of solar power, Chris's figures show that you could easily charge your bike battery during the day directly from the solar panel output, not calling on your House battery at all.
95Ah is not a lot of battery capacity, though. In your position, I would want to upgrade to 200+Ah AGM batteries and at least 300 watts of solar power.

Neville.
 #140071  by Ramber1
 Tue May 01, 2018 7:37 pm
Thanks guys, will look further into it, might have to relocate tv dish further forward to get a bigger panel on the roof.
Rob
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