Most boat owners in the UK have done the responsible thing and insured their boat, but buried deep in the fine print of the policy could be a few lines that leave them high and dry if a battery fails or worse, catches fire.
Most marine policies don’t shout about battery exclusions, but make no mistake, they’re often in there. And unless you understand how they work, your claim could be denied before it’s even reviewed.
This blog unpacks the common hidden battery clauses you need to know about before installing that new lithium-ion battery system or replacing your old AGM setup.
Common Battery-Related Exclusions in Marine Insurance
Here are the most frequent reasons insurers won’t pay out for battery-related claims:
Ageing or natural wear and tear
Batteries don’t last forever, and insurers know it. If your battery fails simply because it’s old, you’re unlikely to be covered.
Poor or irregular maintenance
Corroded terminals? No evidence of servicing? Most policies exclude damage caused by a lack of reasonable care.
Overuse or misuse
Running beyond specified discharge cycles, using the wrong charger, or improper battery pairing? You may breach your policy conditions and void coverage, even if a fire results.
Overcharging and thermal runaway
If it’s shown the battery was overcharged or left on charge unattended (especially lithium-ion batteries), insurers may reject the claim unless you followed charging precautions stated in your policy.
Misdeclared Battery Upgrades or Capacity Increases
Here’s one element that many boat owners don’t realise. Any change to your electrical system, especially moving to lithium-ion, must be declared.
Failing to notify your insurer can trigger policy voidance (non-disclosure of material facts), rejected fire or explosion insurance claims and reduced payout limits.
Even something as simple as adding a second battery bank or swapping in higher-capacity cells could put your claim at risk if it wasn’t on file when the policy was underwritten.
Always tell your insurer if you switch to lithium-ion or AGM, you increase the number of batteries or capacity, you change charging methods (e.g. shore power + solar), or you install a new BMS or upgrade your inverter/charger.
Hull, Machinery & Electrical Coverage: What’s the Difference?
Another policy blind spot is where the battery actually sits within your cover.
| Policy Section | Covers Battery? | Notes |
| Hull | Sometimes | Covers physical damage to the vessel structure, and may include battery damage from fire or flood. |
| Machinery | Maybe | Often covers engines, but batteries might be excluded unless they are integral to propulsion. |
| Electrical Systems | Normally | Covers fixed electrical systems, but only for accidental damage, not degradation or misuse. |
If your battery fails due to a charger fire or electrical fault, the consequences might be covered even if the battery itself is excluded.
Battery Fitting Checklist: What to Do Before You Install
Before you upgrade, modify or replace your batteries, make sure these bases are covered:
Declare the change to your insurer
Include specs, battery type (lithium-ion, AGM), and capacity.
Install according to the manufacturer's standards
Use marine-rated enclosures, correct cabling, and ventilation when installing.
Add specific lithium-ion fire provisions
Many insurers now require lithium-ion battery extinguishers like Firechief® Lith-Ex (AVD-based) onboard.
Keep all documentation
Keep a copy of receipts, installation photos, maintenance logs, and BMS readouts. These help prove compliance if you need to claim.
Review your policy in detail
Look for clauses referencing any of the following:
- “Unattended charging”
- “Fire safety provisions”
- “Excluded equipment or wear items”
- “Modifications and material changes”
If it’s unclear, ask your broker to confirm in writing what’s covered and what isn’t.
Final Thoughts
Batteries may be a small component but they’re at the centre of some of the most serious, costly and contested claims in modern marine insurance.
With lithium-ion battery fires, solar charging setups, and complex BMS integration all becoming common, insurers are rewriting the rulebook, often with clauses most boaters overlook.
In addition to our Lith-Ex fire extinguishers, the Firechief® range of fire safety products also includes fire blankets, suppression systems, signage and products for all types of fires. For information, call us on +44 (0)330 999 0019 or email sales@firechiefglobal.com.
To stay up-to-date with more product news and insights from across the fire safety industry, follow Firechief® Global on LinkedIn.
Disclaimer
The information contained within this blog is provided solely for general informational and educational purposes and is not intended as a substitute for professional advice. Before taking any actions based upon this information, we advise the reader to consult all relevant statutory or regulatory guidance and, where necessary, to consult a qualified fire or industry regulation professional. The use or reliance on any information contained herein is solely at the reader's risk.