The Offshore Voyaging Reference Site

Q&A—Are Battery Desulphators a Good Idea?

41kZZ2EyAPLQuestion

From member Conner:

I was wondering if there is any instance or reason you are aware of where a continuous battery maintainer/desulphator would be bad for AGM batteries? Unfortunately we live on shore power a lot right now, and I wanted to buy a maintainer for our AGM starting batteries to live on, such as this one. [A combined desulphator and charger.]

The distributor said I did not need it, and actually said to not get it. Do you know of any reason why a maintainer/desulphater for AGM batteries, hooked up full time to AGMs, would be harmful? (Full River AGM batteries)


Login to continue reading (scroll down)

More Articles From Online Book: Electrical Systems For Cruising Boats:

  1. Why Most New-To-Us Boat Electrical Systems Must Be Rebuilt
  2. One Simple Law That Makes Electrical Systems Easy to Understand
  3. How Batteries Charge (Multiple Charging Sources Too)
  4. 5 Safety Tips For Working on Boat DC Electrical Systems
  5. 7 Checks To Stop Our DC Electrical System From Burning Our Boat
  6. Cruising Boat Electrical System Design, Part 1—Loads and Conservation
  7. Cruising Boat Electrical System Design, Part 2—Thinking About Systems
  8. Cruising Boat Electrical System Design, Part 3—Specifying Optimal Battery Bank Size
  9. Balancing Battery Bank and Solar Array Size
  10. The Danger of Voltage Drops From High Current (Amp) Loads
  11. Should Your Boat’s DC Electrical System Be 12 or 24 Volt?—Part 1
  12. Should Your Boat’s DC Electrical System Be 12 or 24 Volt?—Part 2
  13. Battery Bank Separation and Cross-Charging Best Practices
  14. Choosing & Installing Battery Switches
  15. Cross-Bank Battery Charging—Splitters and Relays
  16. Cross-Bank Battery Charging—DC/DC Chargers
  17. 10 Tips To Install An Alternator
  18. Stupid Alternator Regulators Get Smarter…Finally
  19. WakeSpeed WS500—Best Alternator Regulator for Lead Acid¹ and Lithium Batteries
  20. Smart Chargers Are Not That Smart
  21. Replacing Diesel-Generated Electricity With Renewables, Part 1—Loads and Options
  22. Replacing Diesel-Generated Electricity With Renewables, Part 2—Case Studies
  23. Efficient Generator-Based Electrical Systems For Yachts
  24. Battery Bank Size and Generator Run Time, A Case Study
  25. A Simple Way to Decide Between Lithium or Lead-Acid Batteries for a Cruising Boat
  26. Eight Steps to Get Ready For Lithium Batteries
  27. Why Lithium Battery Load Dumps Matter
  28. 8 Tips To Prevent Lithium Battery Black Outs
  29. Building a Seamanlike Lithium Battery System
  30. Lithium Batteries Buyer’s Guide—Part 1, BMS Requirements
  31. Lithium Batteries Buyer’s Guide—Part 2, Balancing and Monitoring
  32. Lithium Batteries Buyer’s Guide—Part 3, Current (Amps) Requirements and Optimal Voltage
  33. 11 Steps To Better Lead Acid Battery Life
  34. How Hard Can We Charge Our Lead-Acid Batteries?
  35. How Lead Acid Batteries Get Wrecked and What To Do About It
  36. Equalizing Batteries, The Reality
  37. Renewable Power
  38. Wind Generators
  39. Solar Power
  40. Watt & Sea Hydrogenerator Buyer’s Guide—Cost Performance
  41. Battery Monitors, Part 1—Which Type Is Right For You?
  42. Battery Monitors, Part 2—Recommended Unit
  43. Battery Monitors, Part 3—Calibration and Use
  44. Battery Containment—Part 1
17 Comments
Oldest
Newest
Inline Feedbacks
View all comments
Conor Smith

Thank you John for the great follow-up information!

Best,

Conor

Roland

Well, I installed one of those desulphators 7 years ago. Have not had one electrical failure on instruments etc. which indicates that the spikes do not harm the electronics.

My first set of LifeLines lasted 6 seasons. I never did a equalizing charge. But they had a comfortable marina life most of the time as I was still working and only had 4 weeks vacation + weekend sailing. The first set of batteries was exchanged prematurely. Would probably lasted another season or two.

The curent set of Lifelines have been in the boat 3 season. These batteries are cycled much harder as we are cruising full time 6 month/year. They are still going strong.

If the desulphator do any good I can not say. But I´m pretty sure it is not doing any damage to batteries or instruments. I totally agree that it can not replace the fact that batteries need to fully charged as often as possible.

As I wrote I have never done a equalizing charge. But what I do is to run the battery charger on absorption voltage 14.4V for 16 hours if the batteries have been discharged a longer period. (More than 2-4 days) I believe this might be why I have been successful not having to do the equalizing charge.

When I had open ventilated batteries I learned quickly by measuring the acid that it take much longer time to charge the batteries 100% than what the manufacturer expected. Battery chargers tend to have absorption time between 4-6 hours. This is many times to short to charge the battery to 100 %. My Mastervolt charger can be programmed to max. 8 hours. Even that is to short if the batteries have been discharged for several day between 50-70%. It takes time to charge a battery properly.

Sorry for derailing a little bit:-)

Dave

John

A friend of mine purchased one of these that was solar powered. He connected it to the battery
on his wife’s brand new jeep grand cherokee ( not sure why ). It destroyed the cars E.C.M. She was
not amused. This is just anecdotal but it does give evidence that electronics can be damaged by
the high voltage pulses from these devices even with the battery acting as a buffer.

Chris Phillips

I ran a couple of Pulsetech PowerPulse desulphators on our last boat, which had a pair of Odyssey 2150s and a single Odyssey 1500 for the starter. I used one unit for both the house batteries and a separate unit for the starter. After 4 years of use the batteries seemed strong without any significant degradation. Its worth reviewing the testing that Pulsetech has done, it seems scientific (to me).

Ernest

Hi John,
thank you for the deep insights (again). Regarding concerns about the voltage spikes – couldn’t a voltage stabilizer help to reduce the danger? I’m thinking of a separate DC ring for electronics (and other possibly sensitive devices) only that don’t draw a lot of power, a DC ring that is guarded by a stabilizer such as this: https://www.amazon.com/interVOLT-Isolated-Stabilizer-Regulator-Conditioner/dp/B00K8OGBEC