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When I first fitted out our boat I used a second hand insulated return 24 volt alternator from a commercial breakers yard, It was a good sized beast physically and would happily self excite at about 600 rpm engine speed, so I just connected it with two wires -ve & +B When it went to meet its maker in the scrap yard I replaced it with a larger electrically but smaller physically speaking one. This would not self excite so I fitted an "Ignition" light to it, A sealed push in thing that I had in the bits box. Thinking about it it may have been a 12 volt warning lamp, I cant find any markings on it and its popped. So now I need to replace it which set me thinking. As its a 24 volt alternator would it need to be a higher wattage than a 12 volt one, I am thinking of the current flow in the windings to get excitation. If so what sort of wattage would be needed? If the one I had was 12 volts then I dont know what sort of impedance the field would be so I dont know how much it was over run by and what its equivalent wattage of the bulb would be.

Hello all, Unfortunately despite my best intentions I am need of some advice regarding my battery bank... I have only just become aware that I need to equalised my batteries some how this information slipped my mind during all my research and planning for my batteries. I think I thought my controller or multiplus did it automatically as its soo bloody expensive I have also been relying on my battery monitor telling my my SOC, I now understand this may not be the case. And would appreciate any advice on what I can do now... My system is: 6 x T105 Trojan 6v 225ah batteries that are just over a year old. I rarely run them below 80% and regularly check and top up water. 930w of solar and Outback FastMax controller Victron Multiplus 12/3000/120 Inverter/ Charger Victron BMV700 Battery Monitor Honda eu20i for charging This issue which recently arose... my inverted has started flashing low battery when running my washing machine on a cold wash (which used to be fine) I thought it could be the washing machine malfunctioning as it is an old one but someone said its my batteries and has lead me to learn despite me thinking I am taking good care of them perhaps I am not :/ So, I have bought a hydrometer : https://www.ebay.co.uk/itm/Pro-Hydrovolt-HYDRO-VOLT-Lead-Acid-Battery-Hydrometer-Electrolyte-Tester/322082591860?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 But don't really know what to do with it and would appreciate any advice, I know this is lots written about batteries and I have been reading it but any advice specific to my situation would be greatly appreciated as I don't want to do any more damage to my expensive and rather lovely batteries. Which I am hoping I haven't done too much damage too. I am going to charge my batteries now using my genny and look at the amps going into the batteries to see when a tail current (1-2% of capacity, 6.75 - 13.5amp for my 675ah battery bank) is reached this should hopefully tell me when it they reached 100% more accurately than my battery monitor. I will then run an equalisation charge, I have looked at how to switch this on with my Victron Mulitplus, I will set equalisation to 8.10v (indicated on the trojan website) I am then planing on setting my float charge (on my multiplus settings) to the same as my absorption charge 7.05 - 7.35 as this will bring my batts to 100% state of charge quicker when I am charging as I only charge using a generator I will not leave it running on float for very long. If I have made any errors please let me know, thanks again for any advice. Martin

I'm sure everyone remembers my poor charging regime and the lengthy thread that ensued. I'm still using my set of somewhat reduced capacity 4x110ah batteries - a couple hours engine running in the morning, a couple in the evening, and then switch off the 240v (including fridge) at night. This gives me enough laptop time in the evening, led lights and various pumps etc. So, for now carrying on quite happily - but I have noticed a new phenomenon creeping in lately. Today for example: I ran the engine for an hour or so when I got up (with 240v back on as normal). I then cruised for 3 1/2 hrs. A couple hours later, and my batteries are already back down to 12.3v so I have fired up the engine again. What I am saying is this - it would appear that the leisure batteries are not getting much (or any?) charge when I'm cruising. I can't think what this could be but I'm sure someone will enlighten me - be gentle! Just to re iterate - I know the batteries have reduced capacity, but a couple hours charging off the engine normally sees them up to say 12.8v which lasts all day or all evening. Even on longer cruises, they don't seem to get as much charge as when the engine is just running in neutral. I have two alternators, 50a for engine, 175 for leisure.

Just had some repairs and service done on my Lister SR2 engine after it completely packed up and have now noticed that the batteries are reaching up to 17volts when at full throttle with the battery selector switch set to ‘both’ or position 1 (leisure batteries). If I select position 2 (starter battery) then it is around 14v as normal. Both sets of batteries have taken quite a hammering recently with the number of times the engine had been cranked prior to the repair so did wonder whether a fault had developed on one of the leisure batteries causing it to over charge? I then disconnected the batteries and checked the voltage and they were all around 13 volts. I always keep the batteries charged on shore power but it seems strange that it would register such high voltage so was thinking more likely the alternator. As far as I’m aware it wasn’t touched when the repairs were done as the injectors and fuel system were causing the original problem. Any help most appreciated. Wakes.

Hi there, We have recently been having problems with losing power on our batteries, so around 4 weeks ago, we have 4 new leisure batteries fitted. However the problem has continued. Our inverter has started beeping and the fridge is cutting off, so i think the batteries have lost power. -We had the batteries fitted by experts, so I think they were fitted properly. -We charge the batteries from the engine. And have been running the engine for at least an hour a day and sometimes up to 4 hours to attempt to recharge. -We have only been running lights, fridge, tv (sporadically) and water. No charging/laptops etc. -We only turn the inverter on when we need power from the sockets, which is around an hour a day. -We have been reassured that they were top quality batteries If anybody can help with advice as to why we are losing charge/not charging up, any advice would be appreciated, as we have no power at the moment. I am also worried that the £450 we spent on new batteries has gone to waste and that the batteries are now dead. Thanks