How to charge the battery of self-made electric vehicle with transformer

Electric car charger can say that it doesn't need transformers to make electric car charger's now. They are all switching power supplies. However, switching power supply has high technology content. It is suitable for mass production, so it is not suitable for homemade. Transformer charger can be self-made, but it has high cost and heavy weight. Large volume and so on. If you want to make it yourself, you must first ask the transformer manufacturer to customize one of these transformers. For example, if your electric car is 36V, customize a transformer with 40V greater than 50W. If you simply charge, you can add a few diodes to get a full-bridge circuit to rectify the current. But this can be optimistic. It may be damaged over time. If an overcharge protection circuit is added, it will be troublesome again.