It depends on what for you want to use the batteries.
If you want to use more batteries to get car started more reliably, you must use (equal chemistry and equal voltage) batteries in parallel to get more ampere hours, please use fuses in series with each battery to eliminate danger of fire.
sorry for google translation, im from Fen-Lan and dont write Han.
这取决於你想使用的电池是什麼。
如果你想使用更多的电池来获得汽车起步更可靠，则必须使用（等於化学和相等的电压）电池并联，以获得更多的安培小时，请用保险丝串联每个电池，以消除火灾的危险。
遗憾的谷歌翻译我是来自芬兰和不写汉字
