Swapped out the old alternator on my 32ft Westerly – worth fitting a smart regulator?

Did exactly this on my 32ft sloop two seasons ago and honestly it transformed the charging situation.

The stock alternator was doing a half-hearted job — wandering around 13.8V and calling it done while my lithium bank sat perpetually undercharged. Fitted a Wakespeed WS500 and the difference was night and day. Proper three-stage charging, temperature sensing on the alternator casing (crucial — alternators on boats work hard), and it talks directly to my Victron system via CAN bus so everything plays nicely together.

The big wins for me:

• Alternator temp protection — it'll back off before you cook the windings, something a dumb regulator will never do
• Absorption and float stages that actually match your battery chemistry
• Integration with Victron MPPT and CCGX, so I get a single picture of what's happening across the whole system

One thing worth knowing — if you're running AGM rather than lithium, the stock regulator isn't quite as criminal. The real gains come when you've got lithium aboard and need precise voltage control with a hard charge cutoff.

Worth checking what alternator frame size you've got first. Some older Westerlys have fairly compact units and not all smart regulators mount cleanly without a bracket bodge.

Anyone else running a Wakespeed, or gone a different route — Balmar ARS-5 maybe? Curious whether others have found the CAN bus integration worth the extra setup faff on smaller boats where you're often doing everything yourself on a pontoon in the rain.

@FZ_Builds this is really timely — I'm looking at doing exactly this on my 26ft bilge keeler and the stock alternator is giving me the same vague 13.8V nonsense.

Quick question though: which smart regulator did you end up going with? I've been looking at the Wakespeed WS500 but it feels like overkill for my setup (100Ah Fogstar lithium). Also wondering whether the alternator itself needs to be a specific type to play nicely with it, or whether it'll work with a decent rebuilt unit?

Did you have to do anything special with temperature sensing given the engine bay heat? Mine gets pretty toasty in summer and I'd rather not cook an expensive alternator.

@NicolaTaylor72 a Wakespeed WS500 paired with a decent alternator (I run a Balmar on my shepherd's hut rig, don't judge me) is basically cheating — it'll talk directly to your Victron system via CAN bus and actually think about what your batteries need rather than just lobbing 13.8V at them and hoping for the best.

Key thing people miss: temp sensing on the alternator itself — without it you'll cook the windings on a hot engine bay run, which is an expensive lesson learned the hard way by yours truly.

For a 26ft bilge keeler you probably don't need anything fancy — even a Sterling BB series external regulator will see your LiFePO4s properly bulk-charged rather than that feeble absorption plod the stock unit does.

Not strictly marine but I've been through the smart regulator rabbit hole on my static caravan setup, so some of this translates.

One thing worth flagging that I don't see mentioned yet — temperature compensation becomes really important when you're asking an alternator to push hard into a larger bank. The Wakespeed WS500 @MarineGeoff mentioned handles this well with a dedicated battery temp sensor, which prevents you cooking cells on a warm day when the bank's already partially charged.

Also worth asking yourself:

• What battery chemistry are you running? LiFePO4 versus AGM changes the target voltages significantly
• Is your alternator rated for continuous high-output duty, or will you need to derate it?

On a boat the engine room temps can be brutal. An unprotected alternator pushing into a depleted lithium bank without temp sensing is a recipe for a seized bearing at minimum.

@MarineGeoff a Balmar on a shepherd's hut is genuinely baffling and I have questions, but that's for another thread.

My Westerly 34 had the same half-hearted alternator problem. Fitted a Wakespeed WS500 last winter and the difference with my LiFePO4 bank is night and day — it actually uses the alternator properly rather than faff around at absorption for hours.

One thing nobody's mentioned: temperature sensing. The Wakespeed's alternator temp sensor is not optional in my opinion, especially if you're pushing a bigger alternator hard on a warm engine. Found that out the uncomfortable way before I got organised about it.

@NicolaTaylor72 what's your current battery bank — flooded, AGM, lithium? Changes the setup considerably and the WS500 profile configuration is different for each.

@DodgyMechanic same — the Balmar shepherd's hut thing is living rent-free in my head now 😂

Anyway — yes, smart regulator is absolutely worth it, especially if you've moved to LiFePO4. Stock regulators have no idea what to do with lithium, just wander around bulk forever or worse, undercharge completely.

I run a Victron setup on my cabin rather than a boat, but the principle's identical — proper absorption, tail current cutoff, the works. Night and day vs dumb regulation.

Wakespeed WS500 seems to be the go-to for marine specifically because of the NMEA 2000 integration — you can actually see what's happening on a chartplotter which is handy offshore.

One thing worth checking: your alternator temp. Smart regulators push harder and older alternators can cook themselves. Might be worth a temp sensor at minimum.

Running a similar setup on my 32ft bilge keeler — went with a Victron alternator regulator (the Orion-style external unit) rather than a full Balmar kit, mainly on cost grounds. Made a noticeable difference to how quickly the house bank recovers after an overnight anchorage.

One thing worth flagging for anyone with LiFePO4 on board: the absorption/float profiles matter a lot more than with AGM. I also wired mine to cut output if the Cerbo GX signals full SOC — saves the alternator cooking itself when the batteries are satisfied.

@FZ_Builds what battery chemistry are you running? That'll shape which smart regulator makes most sense. The Wakespeed WS500 gets a lot of love in the bluewater crowd if budget allows, but for coastal stuff there are cheaper options that do the job.