Twin battery instal charging question

[tom020780]

I have just invested in a specific battery for starting the older type of optimax engine (150hp salt water). Reason is that it was thrown on at the end of last year and I used the deep cycle marine battery 110ah which just had not got enough cca to start confidently.

I would like to still use this battery to run all sundries (vhf, stereo, grs, depth, 12v jack charge point) and retain the new battery for just starting. Easy enough to install as I have 2 jockey seats so bags of room for both

Now I am adding a split charge system does it matter that the batteries are different types and specs?

I was pretty sure no issues but wanted to double check. Apart from the split charge kit they are completely independent of each other...

Look forward to any comments / replies

Tom

[Chris]

No issue with using different spec battery, what split charging system are you using ?

[Maximus]

Why bother with Twins?...With the right Battery you don't need a twin set up...especially on a smallish RIB when weight is always an issue.

[tom020780]

Bought from local swindlery (aka chandlery) only branding is AE parts

12v 110amp 3 meter kit - raining outside so searched for similar kit online and Annoyingly just found on eBay for considerably less😁

Pic here

[tom020780]

And thanks for the reply 👍

[tom020780]

Going for twins as often on rescue boat duties and would rather have a spare on board and not worry about battery when engine off long periods with engine off especially some races locally can be out for 5-6 hours at a time - the deep cycle will start the engine if require from reading up these don't suit the optimax's and not sure on performance of new battery that is suited in that situation so would rather not worry and have 2

Rib is 5.5m and a little overpowered so an extra 18kgs won't affect performance and can position in console (slightly forward of centre)

[Erin]

Looks like a nice kit for what you need to wire up, however if you want to really mitigate the risk of failure make sure the cables are tinned and not just plain automotive copper. Assuming both batteries are standard lead-acid there shouldn't be any issues with charging them. Presumably that split-charge relay will prioritise the start battery for charging.

[HDAV]

Originally Posted by Erin

Presumably that split-charge relay will prioritise the start battery for charging.

Depends how you wire it i think there is normally a primary battery connection and this gets charged. When the voltage on that battery reaches a threshold 14V say the relay switches to the secondary battery and charges that.

If primary batt is only doing starting duty it wont take long to recharge so secondary gets plenty of charge time and while sat engine off the primary is not being depleted.

It's basically a relay with a set coil voltage, coil lead run from the primary and the primary connected to the NC contacts when relay triggers the NC contact opens and the NO closes charging feed is the C on the relay.

Worth having a relay with a manual over ride in my opinion (or wire a switch inline with the coil), as if primary batt fails it won't charge secondary