Deep Cycle Battery Testing

[gunflint]

Does anyone know if you can load test a deep cycle battery the same as you would a starting battery?

[jeffreyd]

sure but you should use or have someone use the proper equipment. While i can make a new battery fail using most testers, a Midtronic device is usually what most companies rely on for warranty. Make sure the battery is topped off with water and fully charged, 12.66 vdc is a fully charged battery. this equates to 2.11 volts per cell, 6 cells in a 12 volt battery. You can take it to the place you got it from, or dealer and have them load test it. most likely the first test will come back as recharge and retest. they will want to charge it again and retest. Wat kind of battery are we talking about? Other than that make sure your equipment is working correctly. God luck.

[BobT]

I've never had this done but I would expect it requires different testing equipment than a starting battery simply because a deep-cycle battery is a different design than a starting battery and not designed to deliver the high current. A starting battery is designed to deliver a specific voltage while maintaining a high current supply for a short burst. A deep-cycle battery on the other hand is designed to maintain a specific voltage while delivering a constant low amperage over a long time period. I wonder if the real load test would be to apply a specific load and monitor voltage over a period of time such as hours. I don't know how one can evaluate a deep-cycle battery with a short-term test.

[jeffreyd]

i think a midtronic (higher end) has a setting for deep cycle. Trying to remember what the one in the shop has. I believe you can cycle through single, bank, group, auto or deep.

[gunflint]

I've got a load tester at work that we use on starting batteries. I'll throw them on tonight and see what happens.

[BobT]

i think a midtronic (higher end) has a setting for deep cycle. Trying to remember what the one in the shop has. I believe you can cycle through single, bank, group, auto or deep.

I didn't know there was a tester for deep cycle batteries. Nice to know. I learned something new today.

[Whoaru99]

The Midtronic units rely on (essentially) determining the internal impedance of the battery compared to data for that type and capacity of battery. It does not load them per se, but instead sends some type of signal though the battery to make this measurement.

We have one at work. Seems to work good, but it does rely on using it exactly like the instructions say, including very good contacts to the battery terminals as any unexpected resistance/impedance there can skew the results.

[BobT]

That makes sense.