Charge from Battery Bank without an Inverter to AC

[bsatt69]

Has anyone found a way to charge from a battery bank without using an inverter going to AC? I would think it possible with maybe using a 48V 100AH for a battery, but maybe need a different charger? Could this be done with a mppt controller? This would save cost, complexity and be more efficient. I don't know enough to try something, but it just seems inefficient to go from dc to ac back to dc.

 

[Philip]

@DonCox knows all about it. You can build a SuperCharger for your dirt bike if you really want to be quick and efficient.

FTR Bartow Peace River Hare Scramble All Electric Class

I have a couple friends that got to Race this Hare Scrambles in an All Electric Class. I was not there, so this is just a collection of the info I got, so please correct things that I may have in error, but I am so proud of the DIY riders for there showing and excited in the fact that we, all...

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[DonCox]

Has anyone found a way to charge from a battery bank without using an inverter going to AC? I would think it possible with maybe using a 48V 100AH for a battery, but maybe need a different charger? Could this be done with a mppt controller? This would save cost, complexity and be more efficient. I don't know enough to try something, but it just seems inefficient to go from dc to ac back to dc.

I have done a little bit with this quick charge system idea. So I have a bike with 2 x 20S6P batteries in my YZ250F. We were riding in So Cal in the summer. After one 5-6 lap moto, we came in to charge and it did. I have a Dual Battery switch on it so I could separate them to charge, which I always do. After the second moto, one of the batteries would not charge, the BMS was overheated, so I could only charge one battery. So I had them separated to charge, and now one battery was 82V and one battery was 72V. So I put the switch back in the Both position, and the bike was at 77V . So I could go out for another moto, and repeat. I did this quite a few time that summer.
There was no damage to the batteries over that period of time. So looking at how to make this work long term. To do it right for a 84V battery that was discharged to 72V, and you want to recharge it to 84V, you would need a 96V battery of equal amperage connected to the 72V battery to bring it back to 84V. Now this is a dangerous operation, since there is no BMS involved and the current will be very high for a very short time. I have some large wattage snubber resistors, which I will put in series with this operation. And in between usage of this device look closely at all cell groups, and use a strong Balancing BMS. It is just a idea right now. I replaced that battery system in that bike, but we may be checking this idea out again. We could possibly use the discharge side of a BMS that could carry the current on the 96V battery to control the current flow. More to follow, give me your ideas. The problem with doing this on a Stark is the voltage. 420V is a full charged battery, 360V would be half discharged , so you would need a 480V battery to recharge.