Dynastart as a starter motor only

[lamdar]

Hello, my dynastart regulator is not charging so I bought a new regulator which came as two separate parts— a relay for starting and a voltage regulator for charging. I used the old regulator this year as a starter motor only and charged my starter battery with a 50W solar panel, which worked fine. I’m thinking of doing the rewiring this winter to switch to the new regulator.

My questions is: is it safe to use the starter function (relay) only and leaves the charging regulator unconnected?

The reason I’m thinking of doing this is I want to switch to a single large lithium battery (200Ah) for everything next year and charge it with solar only. I heard that dynastart only uses a little current for starting so I’m sure the lithium battery could cope with it. However I heard lithium battery is prone to damage by overcharging so I can’t hook the lithium directly to the dynastart regulator. And the output is so little (8A I believe, probably less with my old engine) it won’t charge much anyway with an hour engine running. This way I can keep the system super simple.

Is this doable? How do people that converted from dynastart to alternator wire the charging side of the dynastart afterwards?

 

[neil_s]

Hi there, Lamdar, welcome! In the past I have owned boats with both Bosch and Siba dynastarts. I don't think there will be any problem with just using the start facility. Pressing the start button energises the relay which connects the dynastart as a series wound motor. There is a separate coil for the charging circuit, just leave it unconnected. The units I had incorporated the relay inside the regulator - so just a single box - but you could access the relay contacts none the less. I remember the Siba controller being a little unreliable - it needed contacts cleaned every so often - and the Bosch also managed a whole 11 amps charging! This was before the days of solar panels so I needed the charging facility.

 

[Halo]

I used my old boats Dynastart unit for starting only for many years with no problem.

 

[BobnLesley]

I'm another who's used a non-charging dynastart as a starter motor. That said, I recall that I made some alteration to the dynastart/regulator wiring when I did so; unfortunately that was 20 years ago so I can't remember what those changes were.

 

[William_H]

Unlike an alternator with diodes which can be damaged with a disconnect dynastart and dynamos can not be harmed by being disconnected. ol'will

 

[Refueler]

With the Dynastart not charging when you start up - it should be fine ....