Battery For DIY Electric Car Conversion – The AGM Battery

Home/EV Conversion/Battery For DIY Electric Car Conversion – The AGM Battery

Battery For DIY Electric Car Conversion – The AGM Battery

If you are doing a DIY electric car conversion at home, one of the key components that you have to look into is the battery.

For an electric vehicle (EV) instep of the internal combustion engine (ICE), you are now using an electric motor to generate torque. To spin the motor, you need an electric power source, which is the battery pack. What kind of battery should you get for your homemade electric car?

Generally, people will use acid flooded deep cycle battery, just like the one used on electric golf carts. As an alternative, you can also consider the AGM (Absorbed Glass Mat) battery for your electric car.

Benefits of AGM Type Batteries

One of the key difference of this type of battery is the absorbed glass mats used between the plates. The mat is soaked with electrolyte material up to about 95% saturation. This is also called “starved electrolyte” because it is not fully saturated.

Since the mat is not fully saturated, the batteries will not leak in case there is a crack on the casing. This is advantages for electric cars in case you get yourself in an accident. Having 10 – 15 units of battery on board, any acid leaks will be hazardous to the car and the driver.

Since the AGM has no liquid electrolyte, this mean there is no freezing during cold weather and expansion during warm weather issues. They are literally immune to their surrounding temperatures.

Efficiency of AGM

Most AGM batteries are very efficient. They have an efficiency rate of up to 99% when charging, due to the fact that all the hydrogen and oxygen gasses recombine back into water during the charging process. This is effect reduce the chances of water lost.

If you are using AGM for your electric car, you do not need a special charger. Any normal acid type will work just fine. This is great for EV converter that’s working on a tight budget.

Finally, AGM battery has very low self-discharge rate, only 1 to 3% per month. What does this mean? You can literally leave the AGM idle with no charging for extended period of time. When you use it again, you will notice a reasonable charge level. If you were to do this is a conventional acid flooded battery, if left sitting idle for a long time, you will notice a power loss due to self-discharging.

Should You Use AGM Batteries?

Now for the final question…Should you use AGM batteries for you DIY electric car conversion? There are many advantages for an AGM compared to acid flooded battery. It is safer, immune to temperature changes, highly efficient and can hold the charge quite well. The only drawback is its cost. AGM is typically cost 2 -3 time more than a conventional flooded type.

You would have to work out your conversion budget. Compare the pros and cons of using AGM. The end results will be great for you electric car.

Convert Your Own Electric Car

Want to know how to convert a conventional automobile into a plug in electric car? If you do, download the 20 DIY Electric Car Conversion Videos e-book.

The e-book will show you videos of homemade electric cars and the different components needed for the conversion project. Click on the link below to download the free e-book now!

==> Click here to download free e-book!

Related web sites:
1) Electricity4Gas Review – How to Make an Electric Car?

2) Electric Car Conversion Companies: Alternatives To Gas Powered Cars

3) Volkswagen Beetle Electric Car Conversion

By | 2012-08-17T14:10:40+08:00 June 26th, 2009|EV Conversion|2 Comments

About the Author:


  1. […] The old battery can be re-conditioned to make a new battery by some factories. However, there is yet another type of battery which is known as waterless battery. […]

  2. austin September 8, 2010 at 1:43 pm

    It is an excellent blog about battery for DIY electric car conversion. I would like to say few points about AGM.
    1. Nearly all AGM batteries are “recombinant” – what that means is that the Oxygen and Hydrogen recombine inside the battery. These use gas phase transfer of oxygen to the negative plates to recombine them back into water while charging and prevent the loss of water through electrolysis. The recombining is typically 99+% efficient, so almost no water is lost.
    2. AGM’s have a very low self-discharge – from 1% to 3% per month is usual. This means that they can sit in storage for much longer periods without charging than standard batteries.
    3. AGM’s do not have any liquid to spill, and even under severe overcharge conditions hydrogen emission is far below the 4% max specified for aircraft and enclosed spaces. The plates in AGM’s are tightly packed and rigidly mounted, and will withstand shock and vibration better than any standard battery.

Leave A Comment